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EXPERIMENTAL INVESTIGATION OF

THERMOCHEMICALLY-DERIVED FUELS IN A

DIESEL ENGINE

Md Farhad Hossain

Masters of Science (Mechanical Engineering)

Khulna University of Engineering & Technology (KUET), Bangladesh.

Supervisors:

Professor Richard Brown

Senior Lecturer Dr. Thomas Rainey

Professor Zoran Ristovski

A thesis by publication submitted in fulfilment of the requirements for the

Degree of Doctor of Philosophy (PhD)

Chemistry, Physics and Mechanical Engineering School

Science and Engineering Faculty

Queensland University of Technology

2018

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine ii

Statement of Original Authorship

The work contained in this thesis has not been previously submitted to meet

requirements for an award at this or any other higher education institution. To the best

of my knowledge and belief, the thesis contains no material previously published or

written by another person except where due reference is made.

Signature: QUT Verified Signature

Date: January 2018

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine iii

Abstract

There is a growing demand for transport liquid fuel and industrialised countries

have already started to use alternative fuels as substitutes for fossil fuel. Many highly-

innovative technologies have achieved early commercial status for alternative liquid

fuel production. One such technology is the thermochemical conversion process,

which can convert a wide range of alternative feedstocks into fuels without pre-

treatment, thereby reducing the production cost of the fuel. Hydrothermal liquefaction

(HTL) and pyrolysis methods are commonly used as thermochemical processes to

produce alternative fuels.

This research focuses on thermochemical conversion of feedstocks and is

divided into two streams. The first investigates the use of wet microalgae feedstocks,

using HTL, to produce biocrude. The second stream explores the use of dry waste tyre

feedstocks using Green Distillation Technology (GDT), a modified pyrolysis process,

to make tyre oil.

In the first stream, wet microalgae feedstock was used to produce biocrude via

the HTL method. The impact of the fuel on a diesel engine was investigated.

Microalgae is more scalable and has greater ability to supply a significant proportion

of world energy compared to most types of biofuel feedstock. HTL is well suited to

wet biomass (such as microalgae) as it greatly reduces the energy requirements

associated with dewatering and drying. The present experimental analyses of the

physicochemical properties of biocrude oil produced via HTL uses a high-growth-rate

microalgae, Scenedesmus sp., in a large-batch reactor. Batch reactors overcome issues

with feeding against the high pressure required (200 bar) and can adapt to different

feedstocks easily. Literature relating to HTL mostly reports on work using very small-

batch reactors, which are preferred by researchers, so there are few experimental and

parametric measurements for the physical properties of biocrude such as viscosity and

density. In this study, a difference between the traditional calculated values and the

measured values was found. Under optimum conditions, even though the measured

higher-heating value (HHV) was lower (29.8 MJ kg-1), the high density (0.97–1.04 kg

L-1) of HTL biocrude and its high viscosity (70.7–73.8 mm2 s-1) made it similar enough

to marine heavy fuels that could be immediately used without further processing. The

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine iv

batch reactor would be expected to produce more compounds due to slower heat-up

and cool-down time—likely 10–20 compounds comprising aromatics and

heterocyclics. The reaction temperature was explored in the range of 280–350 °C and

biocrude oil yield and HHV reached their maxima at the highest temperature. Slurry

concentration was explored between 15–30% at this temperature and the best HHV,

O:C and N:C, was found to occur at 25%. Two solvents (dichloromethane (DCM) and

n-hexane) were used to recover biocrude oil, affecting the yield and chemical

composition of the biocrude. Biocrude obtained by HTL for green freshwater

microalgae contained 10–11% (wt.) oxygen, 4–8% (wt.) nitrogen and 32–35 MJ/kg

calorific value (20–27% lower than for petroleum diesel).

Microalgae biocrude is not suitable to use in a transport diesel vehicle due to its

high density and viscosity compared to diesel. To investigate the effect of microalgae

HTL biocrude on diesel engine performance and exhaust emissions, a surrogate fuel

was developed. The chemical compound of the surrogate fuel was selected from

microalgae HTL biocrude. Approximately 65% of microalgae biocrude chemical

compounds were blended in different proportions to prepare a surrogate fuel similar to

diesel. The engine experiment was conducted on a diesel engine in the Biofuel Engine

Research Facility (BERF) at the Queensland University of Technology (QUT).

Exhaust emissions, including particulate and gaseous emissions, were investigated and

a significant reduction was found in particle matter (PM), particle number (PN), and

Carbon monoxide (CO) for all 10%, 20% and 50% blends except NOx, which

increased around 15–20% when compared to diesel fuel. There were no significant

changes found with microalgae HTL surrogate blends in the engine performance

parameters, including brake power (BP), brake mean effective pressure (BMEP) and

brake thermal efficiency (BTE).

In the second stream, waste-tyre feedstock was used to produce oil using the

GDT method and the impact of that fuel on a diesel engine was investigated. Globally,

there is a growing problem of waste-tyre disposal. End-of-life tyres (ELTs) are a

significant and growing environmental hazard. Around one billion waste tyres are

generated worldwide every year. This total is expected to increase to 1.5 billion by

2020. Therefore, waste-disposal-tyre-to-fuel technology offers a very promising

solution for both issues. The tyres are an organic waste from which useful energy in

the form of liquid, gas or solid, can be derived. Meanwhile, the calorific values of

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine v

rubber from tyres are 35–40 MJ/kg, so vehicle tyres appear a very promising feedstock

for fuel. Hence, such a solution is most effective and useful as it not only resolves the

challenge of waste tyre management but also provides output that can be further used

in a wide range of applications including diesel engine as a transport fuel. The

physiochemical properties of the GDT-tyre oil are like diesel fuel and the fuel can be

mixed with diesel in any blend ratio. The engine experiment was conducted with a

diesel engine in the Biofuel Engine Research Facility (BERF) at QUT. A substantial

change was found in NOx emissions, which cut off around 30% for both 10% and 20%

blends when compared to diesel fuel. PM and PN were reduced by 35%–60% and 5–

20% respectively for both blends and CO increased by around 2%–3% with respect to

diesel emissions. No significant changes were found in engine performance parameters

with GDT-tyre-oil blends.

Thus, this study represents a significant contribution to the existing literature by

evaluating two different thermochemical conversion methods. This is the first time

microalgae HTL surrogate fuel has been tested in a diesel engine. Similarly, this is first

time the engine performance and exhaust emissions of GDT-tyre oil have been tested.

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine vi

Table of Contents

Statement of Original Authorship ............................................................................................ ii

Abstract ................................................................................................................................... iii

Table of Contents .................................................................................................................... vi

List of Figures ....................................................................................................................... viii

List of Tables ........................................................................................................................... xi

Keywords ............................................................................................................................... xii

List of Acronyms ................................................................................................................... xiii

Acknowledgements ................................................................................................................ xv

List of Publications ............................................................................................................... xvii

Chapter 1: Introduction .................................................................................... 21

1.1 Background and motivation ......................................................................................... 21

1.2 research objectives ....................................................................................................... 25

1.3 Research questions ....................................................................................................... 26

1.4 Research approach ....................................................................................................... 28

Chapter 2: Contribution of thesis ..................................................................... 30

Chapter 3: Literature review on diesel engine performance using microalgae

FAME and the prospects of HTL biocrude ........................................................... 33

3.1 introduction .................................................................................................................. 37

3.2 Microalgae biomass to biofuel conversion technologieS ............................................. 38

3.3 Engine performance and emissions .............................................................................. 46

3.4 Conclusion ................................................................................................................... 52

3.5 Acknowledgements ...................................................................................................... 52

Chapter 4: Literature review on thermochemical conversion of waste

tyres .......................................................................................................... 53

4.1 Introduction .................................................................................................................. 54

4.2 Waste tyre to oil using thermochemical conversion .................................................... 55

4.3 Waste Tyre to oil, carbon and steel .............................................................................. 58

4.4 Diesel engine performance and exhaust emission using tyre oil.................................. 60

4.5 Conclusion ................................................................................................................... 62

Chapter 5: Experimental measurements of physical and chemical properties

of microalgae biocrude using a large-batch reactor ............................................. 63

5.1 Introduction .................................................................................................................. 67

5.2 Materials and methods ................................................................................................. 69

5.3 Results and discussion ................................................................................................. 72

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine vii

5.4 Conclusion ....................................................................................................................85

5.5 Acknowledgments ........................................................................................................86

Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine

performance and exhaust emissions using surrogate fuels .................................. 87

6.1 Introduction ..................................................................................................................91

6.2 Concept of microalgae HTL surrogate .........................................................................93

6.3 Materials and methods ................................................................................................100

6.4 Results and discussion ................................................................................................104

6.5 Conclusion ..................................................................................................................120

6.6 Acknowledgements.....................................................................................................121

Chapter 7: Investigation of diesel engine performance and exhaust emissions

using tyre oil ........................................................................................................ 123

7.1 Introduction ................................................................................................................127

7.2 fuel production and preparation ..................................................................................128

7.3 Materials and Methods ...............................................................................................129

7.4 Results and discussion ................................................................................................132

7.5 Conclusion ..................................................................................................................146

7.6 Acknowledgements.....................................................................................................147

Chapter 8: Conclusions and Recommendations ........................................... 149

8.1 Conclusion ..................................................................................................................149

8.2 Application of outcomes .............................................................................................152

8.3 Limitations ..................................................................................................................152

8.4 Recommendations and future studies .........................................................................153

Bibliography ........................................................................................................... 156

Appendices .............................................................................................................. 171

Biofuel engine research FACILITY (BERF) at QUT ...........................................................171

APPENDIX A: Microalgae HTL biocrude production .........................................................172

APPENDIX B: Fuel Certificate ............................................................................................173

APPENDIX C: Diesel engine performance with surrogate blends .......................................175

APPENDIX D: Diesel engine performance tyre-oil blends ..................................................179

APPENDIX E: Biofuel engine research FACILITY (BERF) at QUT..................................182

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine viii

List of Figures

Figure 1.1: Conceptual flow chart of dissertation. ..................................................... 29

Figure 3.1: Classification microalgae conversion processes [60]. ............................. 39

Figure 3.2: Solvent-extraction and transesterification SET process. ......................... 40

Figure 3.3: HTL process and product separation [33]. .............................................. 41

Figure 4.1: Thermal cracking of waste tyre [158]. ..................................................... 58

Figure 5.1: HTL product recovery workflow. ............................................................ 70

Figure 5.2: Effect of solvent on the recovery of biocrude, solids and gas +

aqueous components after HTL treatment (350 °C, 60 min, 25% slurry

concentration). .............................................................................................. 73

Figure 5.3: Influence of the reaction temperature on product yields at 25%

solids concentration and 60 min reaction time in a nitrogen

atmosphere (2 bar at commencement), values are for yield data. ................ 74

Figure 5.4: Effect of slurry concentration on the recovery of biocrude, solids

and gas + aqueous components after HTL treatment (350 °C, 60 min).

Standard deviations are based on 2 replicates; values provided are for

yield data. ..................................................................................................... 75

Figure 5.5: Van Krevelen diagram of biocrudes gained for different

temperatures (280, 300 and 350 °C) and slurry concentrations (15%,

20% and 30%) in comparison with diesel and FAME biodiesel

standards [196]. ............................................................................................ 81

Figure 6.1: Weight percentage of chemical compounds in microalgae HTL

biocrude. ....................................................................................................... 94

Figure 6.2: Major chemical compounds of microalgae HTL biocrude [215]. ........... 94

Figure 6.3: Chemical structure of (a)1,4 dimethyl, benzene and (b)

Ethylbenzene. ............................................................................................... 95

Figure 6.4: Chemical structure of (a) 3-methyl, 2-cyclopenten-1-one, (b) 2,3-

dimethyl, 2-cyclopenten-1-one and (c ) Cyclopentene. ............................... 96

Figure 6.5: Chemical structure of undecane. .............................................................. 96

Figure 6.6: Chemical structure of (a) 4-hydroxy-4-methyl and (b) butanol. ............ 97

Figure 6.7: Chemical structure of di-(2-propylpentyl) ester. ..................................... 97

Figure 6.8: Proposed roadmap for development of microalgae HTL surrogate

fuels. ............................................................................................................. 99

Figure 6.9: Percentage of chemical compound of a new microalgae HTL

surrogate. ...................................................................................................... 99

Figure 6.10: Blended microalgae HTL surrogate for engine test. ............................ 100

Figure 6.11: Schematic diagram of the engine exhaust measurement system

used for this study. ..................................................................................... 104

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine ix

Figure 6.12: IP and BP variation with IMEP for different fuels. ............................. 105

Figure 6.13: BTE and BSFC variation with IMEP for different fuels. .................... 106

Figure 6.14: ITE and ISEC variation with IMEP for different fuels. ...................... 107

Figure 6.15: Variation of pressure with crank angle for 100% load for different

fuels. ........................................................................................................... 109


fuels. ........................................................................................................... 109


fuels. ........................................................................................................... 110


fuels. ........................................................................................................... 110

Figure 6.19: Effect of Microalgae HTL surrogate blended fuels on peak

pressure and rate of pressure rise. .............................................................. 111

Figure 6.20: Effect of Microalgae HTL surrogate blended fuels on boost

pressure. ..................................................................................................... 112

Figure 6.21: Brake-specific nitrogen dioxide (NO2) emissions for four different

load. ............................................................................................................ 113

Figure 6.22: Brake-specific nitrogen oxide (NOx) emissions for four different

loads. .......................................................................................................... 114

Figure 6.23: Percentage increases of NOx emissions compared to reference

diesel. ......................................................................................................... 114

Figure 6.24: Brake-specific CO emissions for four different loads. ........................ 115

Figure 6.25: Percentage reduction of CO emissions compared to reference

diesel. ......................................................................................................... 115

Figure 6.26: Variation of brake-specific particulate mass for different loads. ........ 117

Figure 6.27: Percentage of reduction of particulate mass emissions compared to

reference diesel. ......................................................................................... 117

Figure 6.28: Variation of brake-specific PN for four different loads. ..................... 118

Figure 6.29: Percentage reduction of PN emissions compared to reference

diesel. ......................................................................................................... 118

Figure 7.1: Schematic diagram of the engine exhaust measurement system used

for this study. ............................................................................................. 132

Figure 7.2: IP and BP variation with IMEP for three different fuels. ...................... 133

Figure 7.3: BTE and BSFC variation with IMEP for three different fuels. ............. 135

Figure 7.4: ITE and ISEC variation with IMEP for three different fuels. ............... 135

Figure 7.5: Variation of cylinder pressure with crank angle at 100% load for

three different fuels. ................................................................................... 137

Figure 7.6: Variation of cylinder pressure with crank angle at 50% load for

three different fuels. ................................................................................... 137

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine x

Figure 7.7: Variation of cylinder pressure with volume at 100% load for three

different fuels. ............................................................................................ 138


different fuels. ............................................................................................ 139

Figure 7.9: Effect of tyre oil on peak pressure. ........................................................ 140

Figure 7.10: Brake-specific NO2 emissions for four different loads. ....................... 142

Figure 7.11: Brake-specific NOx emissions for four different loads. ....................... 142

Figure 7.12: Brake-specific CO emissions for four different loads. ........................ 143

Figure 7.13: Variation of brake-specific PM emissions for different loads. ............ 145

Figure 7.14: Variation of brake-specific PN emissions for four different loads. ..... 145

Figure 8.1: Microalgae hybrid conversion process. ................................................. 153

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xi

List of Tables

Table 3.1: Influence of fuel properties on heavy-duty diesel emissions [57, 81,

82]. ............................................................................................................... 42

Table 3.2: Solvent-extraction microalgae biofuel properties [3, 86, 87]. .................. 44

Table 3.3: Elemental analysis and HHV of microalgae HTL biocrude. .................... 45

Table 3.4: FAME versus HTL microalgae biofuel properties in comparison

with conventional diesel and HFO. .............................................................. 46

Table 3.5: Influence of microalgae biodiesel (FAME) on exhaust emissions

[116]. ............................................................................................................ 48

Table 3.6: Qualitative comparison between microalgae HTL biocrude and

HFO.............................................................................................................. 50

Table 3.7: Exhaust emissions for different ocean-going vessel using

HFO/MFO/residual. ..................................................................................... 51

Table 4.1: Major components of tyres [135, 137, 140, 141]. ..................................... 55

Table 4.2 Collection of pyrolysis reactors and product yield from the pyrolysis

of waste tyres. .............................................................................................. 57

Table 4.3: Physicochemical properties of tyre oil, WCBD and diesel. ..................... 59

Table 4.4: Properties of waste-tyre chars. .................................................................. 60

Table 5.1: Microalgae proximate and ultimate analyses data. ................................... 71

Table 5.2: Major compounds of recovered bio-oils obtained from HTL (350

°C, 60 min, 2 bar nitrogen atmosphere) using two different extraction

solvents (DCM and n-hexane). .................................................................... 77

Table 5.3: Major compounds of recovered bio-oils obtained from HTL under

various solid concentrations and temperature using (DCM). ...................... 78

Table 5.4: Ultimate analysis and HHV of the microalgae biocrude. ......................... 80

Table 5.5: Comparison of chemical and physical properties of biocrude

produced at 350 °C and 25% solids with trans-esterified microalgae

biodiesel, diesel, biodiesel and marine fuels standards [52]. ....................... 82

Table 5.6: Comparison of results from this study with literature. ............................. 84

Table 6.1: Test engine specification. ....................................................................... 101

Table 6.2: Properties of diesel and surrogate chemical compounds. ....................... 102

Table 6.3: Properties of diesel, surrogate and surrogate blends. .............................. 103

Table 7.1: GDT recycled product and quantity based on tyre types [18]. ............... 129

Table 7.2: Test-engine specifications. ...................................................................... 130

Table 7.3: Properties of diesel, tyre oil and their blends. ......................................... 131

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xii

Keywords

Alternative fuel

Biomass

Biodiesel

Biocrude

Diesel engine

Engine performance

Exhaust emissions

Fatty acid methyl esters

First generation alternative fuels

Hydrothermal liquefaction

Microalgae

Second generation alternative fuels

Tyre oil

Thermochemical conversion

Thermochemical conversion

Pyrolysis

Waste tyre

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xiii

List of Acronyms

Abbreviation

BP Brake Power

BMEP Brake Mean Effective Pressure

BTE Brake Thermal Efficiency

BSFC Brake-Specific Fuel Consumption

CI Compression Ignition

CN Cetane Number

CO Carbon Monoxide

DCM Dichloromethane

DOP Dioctyl phthalate

ELT End-of-life Tyre

FAME Fatty Acid Methyl Esters

GC-MS Gas Chromatography with Mass Spectroscopy

GHG Greenhouse Gas

GDT Green Distillation Technology

HTL Hydrothermal Liquefaction

HFO Heavy Fuel Oil

HHV Higher-Heating Value

HC Hydrocarbon

IC International Combustion

IP Indicated Power

IMEP Indicated Mean Effective Pressure

ITE Indicated Thermal Efficiency

ISFC Indicated Specific Fuel Consumption

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xiv

LFO Light Fuel Oil

LHV Lower Heating Value

MFO Marine Fuel Oil

NOx Nitrogen Oxide

PM Particulate Matter

PN Particle Number

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xv

Acknowledgements

The completion of this PhD is attributed to the immense support received from

numerous QUT members. I am tremendously grateful to my advisor and Principal

Supervisor, Professor Richard Brown, for his continuing support, guidance and

encouragement throughout my PhD and beyond. Professor Richard Brown kept me on

track whilst allowing me the freedom to explore my ideas. I am also very grateful for

receiving huge support from my multi-disciplinary supervisory team. Along with

Professor Richard Brown, Professor Zoran Ristovski was the other Chief Investigator

on this project. Professor Zoran Ristovski was mainly involved with the exhaust

emissions of the diesel engine in this research. Together with Professor Richard Brown

and Professor Zoran Ristovski, Dr Thomas Rainey was also involved in the microalgae

fuel preparation and analysis in this research. Dr Thomas Rainey also assisted me to

implement my research ideas and gave me support in designing this thesis.

I would like to thank Green Distillation Technology Corporation (GDTC) and

Trevor Bayley (Chief Operating Officer of GDTC) for their support of the tyre-oil

project. GDTC were very supportive of my work and I look forward to continued good

relations with them and the possibility of further research. I wish to thank to Michelle

Bayley for volunteer English proofreading.

I would like to acknowledge Dr Tim Bodisco, Dr Md Mostafizur Rahman, Dr Md

Nurun Nabi, Dr Md Jahirul Islam, Dr Kabir Adewale Suara, Dr Md Aminul Islam, Dr

Ali Zare, Ashrafur Rahman, Thuy Chu Van and Mohammad Jafari for their assistance

with reviewing the manuscripts that have been published as part of this PhD project. I

also wish to thank to Zoe Staines for English proofreading. I would like to extend my

great thanks to Niki Widdowson, Denis Randall, and Dennis Rutzou for their help in

the waste-tyre oil project.

I would like to give special thanks to Noel Hartnett for his help conducting

experiments. I wish to also extend my gratefulness to all of the members and staff of

the Science and Engineering Faculty and Engineering Precinct, as well as Richard’s

final project students for their ongoing support of my candidature and research.

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xvi

I acknowledge the financial support received from QUT, via QUT’s

postgraduate research scholarships (QUT-PRA). I would also like to give thanks to the

QUT Central Analytical Research Facility for their assistance.

My heartfelt thanks go to my family. This work couldn’t have been completed

without their pure devotion, sacrifice and continued prayers towards my success. Their

encouragements kept me going when there seemed to be no way forward. In particular,

I would like to extend my heartfelt thanks to my wife, Nazia Zabin, for her steady

mental support, consideration, patience, help, and encouragement.

Finally, I wish to thank my colleagues and friends in QUT and Brisbane for

their moral support. In the same way, I wish to give my sincere appreciation to my

parents, my sister and Mentor for their guidance.

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xvii

List of Publications

Papers directly related to this thesis are numbered below:

PEER-REVIEWED JOURNALS

(1) Hossain F.M., Rainey T.J., Ristovski Z., Brown R.J. Performance and

exhaust emissions of vehicle and marine compression ignition engines using

microalgae FAME and the prospects for microalgae HTL biocrude, Renewable and

Sustainable Energy Review, Available online 16 June 2017.

This research article is related to objective 1 and chapter 3 of this thesis;

(2) Hossain F.M., Kosinkova J., Brown R.J., Ristovski Z., Stephens E.,

Hankamer B., Rainey T.J. Experimental Investigations of Physical and Chemical

Properties for Microalgae HTL Bio-Crude Using a Large Batch Reactor. Energies,

2017, 10(4): p. 467.

This research article is related to objectives 1, 2 and chapter 5 of this thesis;

(3) Hossain F.M., Rainey J.T., Nabi N.M., Bodisco T., Suara K., Rahman

M.M., Rahman S., Chuvan T., Ristovski., and Brown R.J. Development of new series

microalgae HTL surrogate fuels and their influence on diesel engine performance and

exhaust emissions. Journal of Energy Conversion and Management, 2017;152

(Supplement C):186-200.

This research article is related to objective 3 and chapter 6 of this thesis;

(4) Hossain F.M., Rainey, T.J., Bodisco T., Bayley T, Randall D., Ristovski Z,

Brown R.J. Investigation of diesel engine performance and emissions using tyre-oil

blends. Journal of Fuel (under review).

This research article is related to objective 4 and chapter 7 of this thesis.

PEER-REVIEWED CONFERENCES

(5) Hossain F.M., Kosinkova J., Brown R.J., Ristovski Z., Stephens E., and

Rainey T.J. The chemical-physical properties of biocrude derived from the

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine

xviii

hydrothermal liquefaction of algae. 5th International conference on Algal Biomass,

Biofuel & Bio-production 7-10 June, 2015-San Diego, USA

(6) Hossain F.M., Nabi M., Rahman M.M., Zare A., Rainey T., Stuart D.,

Ristovski Z., and Brown R.J., Experimental investigation of the effects of oxygenated

fuels on exhaust emissions in a heavy-duty diesel engine. Australian Combustion

Symposium, 7-9 December, University of Melbourne, Vic 2015:56-9.

PEER-REVIEWED POSTER

(7) Hossain F.M., Islam A., Rainey R.J., Kosinkova J., Ristovski Z, Stephens

E., Helmann K., and Brown R.J. Biofuel from microalgae: solvent-extraction Vs

liquefaction. ICFS-2015 Conference at India in 7th February 2015.

Papers that have been published during candidature as a co-author:

PEER-REVIEWED JOURNALS

Nabi MN, Zare A, Hossain FM, Bodisco TA, Ristovski ZD, Brown RJ. A

parametric study on engine performance and emissions with neat diesel and diesel-

butanol blends in the 13-Mode European Stationary Cycle. Energy Conversion and

Management 2017;148:251-9.

Nabi M.N., Rahman M.M., Islam M.A., Hossain F.M., Brooks P., Rowlands

W.N., Tulloch J., Ristovski Z., Brown R.J. Fuel. Characterisation, engine

performance, combustion and exhaust emissions with a new renewable Licella biofuel.

Energy Conversion and Management. 2015; 96:588-98.

Nabi M.N., Zare A., Hossain F.M., Rahman M.M., Bodisco T., Ristovski Z.,

and Brown R.J. Influence of fuel-borne oxygen on European Stationary Cycle: Diesel

engine performance and emissions with a special emphasis on particulate and NO

emissions. Energy Conversion and Management. 2016; 127:187-98.

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xix

Zare A, Nabi MN, Bodisco TA, Hossain FM, Rahman M, Van TC, et al. Diesel

engine emissions with oxygenated fuels: A comparative study into cold-start and hot-

start operation. Journal of Cleaner Production 2017.

Zare A., Nabi M.N., Bodisco T.A., Hossain F.M., Rahman M.M., Ristovski Z.,

and Brown R.J. The effect of triacetin as a fuel additive to waste cooking biodiesel on

engine performance and exhaust emissions. Fuel. 2016; 182:640-9.

Zare A., Bodisco T., Nabi N., Hossain F.M., Rahman M.M., Ristovski Z., and

Brown R.J. The influence of oxygenated fuels on transient and steady-state engine

emissions. Energy. 2017; 121:841-53.

Zare A, Bodisco TA, Nabi MN, Hossain FM, Ristovski ZD, Brown RJ. Engine

performance during transient and steady-state operation with oxygenated fuels. Energy

& Fuels 2017.

Jahirul MI, Brown RJ, Senadeera W, Ashwath N, Rasul MG, Rahman MM,

Hossain FM, Moghaddam L, Islam MA, O’Hara IM. Physio-chemical assessment of

beauty leaf (Calophyllum inophyllum) as second-generation biodiesel feedstock.

Energy Reports. 2015; 1:204-15.

PEER-REVIEWED CONFERENCES

Nabi N., Zare A., Hossain F. M, Rahman M.M., Stuart D., Ristovski Z., and

Brown R.J. Formulation of new oxygenated fuels and their influence on engine

performance and exhaust emissions. Proceedings of the 2015 Australian Combustion

Symposium: The Combustion Institute Australia and New Zealand Section; 2015. p.

64-7.

Zare A. Bodisco T., Nabi N., Hossain F. M., Rahman M.M., Stuart D., Ristovski

Z., and Brown R.J. Impact of Triacetin as an oxygenated fuel additive to waste cooking

biodiesel: transient engine performance and exhaust emissions. Proceedings of the

2015 Australian Combustion Symposium: The Combustion Institute Australia and

New Zealand Section; 2015. p. 48-51.

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xx

PEER-REVIEWED POSTER

Nabi N., Zare A., Hossain F.M., Rahman M.M, Ristovski Z., and Brown R.J.

Steady-state transient diesel engine test cycle: Issues associated with the introduction

of bio-fuel. ICFS-2015 Conference at India in 7th February 2015.

Chapter 1: Introduction 21

Chapter 1: Introduction

1.1 BACKGROUND AND MOTIVATION

In recent years, several highly-innovative conversion technologies have seen the

production of alternative fuels increase. Among these, many thermochemical

conversion processes have achieved commercial status due to their production of

liquid fuel [1]. Conversely, the growing demand for liquid fuel for transport around

the world mostly depends on fossil fuels and is responsible for raising the global

temperature due to pollution [2]. As a result, researches are using advanced

technologies to find alternative fuels that could be used as a substitute for fossil fuel

and reduce exhaust emissions [3-6]. Many researchers have developed different

alternative fuels, most of which are categorised as first-generation or second-

generation alternative fuels [6-8]. First-generation alternative fuels are those that have

been derived from sources such as starch, sugar, animal fats or vegetable oil. Oil is

obtained using conventional production techniques, the most common being a process

called transesterification. This process involves only a few steps from feedstock to

alternative fuel. However, the food versus fuel issue causes some debate over first-

generation fuel production. Because of this, researchers have tried to find a next-

generation fuel, i.e. second-generation fuel [8]. This differs from the first-generation

biofuels insofar as the feedstock used in producing second-generation biofuels are

generally not food crops. Second-generation biofuels are derived from different

feedstock including lignocellulosic biomass, municipal solid waste, waste tyre,

electrical waste etc. Different technology is often used to extract energy from them in

the form of fuel. In most cases, second-generation feedstock is processed differently

to first-generation biofuels, and often uses a thermochemical conversion.

However, dry extraction processes are the established methods used to separate

high-protein cake and high-added-value co-products that contribute to improve the

economic performance of the system. Chemical solvent extraction is the most common

method used to extract lipids from oil seeds. The efficiency of the solvent extraction

process is strongly dependent on the specific algae strain under consideration [9-11].

Wet-extraction processes can avoid these drying steps. In a wet pathway, cell

Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 22

disruption is caused by thermochemical methods. Thermochemical conversion is the

use of heat, with or without the presence of oxygen, to convert various feedstocks into

other forms of energy. Among different thermochemical conversion processes,

pyrolysis and hydrothermal conversion are most popular because of their smooth

operation [11]. Those processes are used to transform the component into fuels along

with other related hydrocarbon (HC)-based products. The particular feedstock, for

example its size or whether it is wet or dry, is also important when selecting the

conversion technique [11]. Thermochemical methods are available for both dry and

wet feedstocks, pyrolysis being used for dry feedstocks and hydrothermal liquefaction

(HTL) for wet feedstocks.

The present research on microalgae and waste-tyre conversion falls into two

groups. The first is based on wet microalgae to biocrude using HTL and the second is

based on dry waste tyre to tyre oil using Green Distillation Technology (GDT), a

thermochemical conversion process similar to pyrolysis.

The pyrolysis process, among other similar thermochemical processes, is

assumed to be most friendly to the environment. The pyrolysis process involves the

decomposition of the second-generation feedstock into products that have lower

molecular weight in an arrangement of limited temperatures. The process involves the

decomposition of the solid at a considerably inflated temperature of around 300 °C to

900 °C in an environment that is free of oxygen and resultantly producing char, oil and

gas. Deploying this process, an important source of energy can be derived and the

resulting components can be used as a source of transport fuel. There has been great

interest in pyrolysis as a thermochemical method to process waste tyres [12]. Cumali

and Huseyin [13] experimentally investigate waste vehicle tyre to oil, using a catalytic

pyrolysis process. They found the fuel to be like fossil fuel. Martínez et al. [14]

demonstrated the waste-tyre pyrolysis process on a pilot scale in a continuous auger

reactor. A large number of research articles described pyrolysis as an attractive method

to recycle waste tyre to tyre oil, steel, and rubber [15-17]. It has many advantages,

including management of the waste-tyre disposal problem, compared to other

thermochemical processes such as combustion and gasification [16]. On the other

hand, GDT has achieved an Australian world technological breakthrough by

successfully and commercially recycling end-of-life car and truck/bus tyres (ELTs)

into the valuable commodities of oil, carbon, and steel. ELTs are a blight on the


environment because, until now, no means have been found to effectively and

profitably recycle them [18]. However, using a technique known as destructive

distillation, a kind of pyrolysis, GDT is able to turn this wasted resource and

environmental hazard into the high demand valuable raw materials of tyre oil, carbon,

and steel. However, the process involves dry feedstock, which may extend the length

of the process and is unsuitable for wet-biomass feedstocks.

To overcome this limitation, a HTL process could be used. Conversely, HTL is

a thermal depolymerisation method to convert wet biomass into biocrude at an elevated

temperature and pressure. HTL converts biomass into biocrude oil as well as aqueous,

gas and solid phase products at elevated pressures (5–24 MPa) and moderate

temperatures (250–400 °C). In general, the variation in the biochemical composition,

particularly the carbon-chain length and the degree of saturation, affects the conversion

rate of the HTL biocrude. HTL converts biomass into gas, liquid and solids similar to

pyrolysis, but operates at a higher pressure and at a lower temperature.

Microalgae biomass present the following advantages: rapid growth, high oil

yield per unit area, ability to grow in saline water, and an ability to be cultivated on

non-arable land [11]. The number of research studies carried out on the subject of

thermal treatment of microalgae has increased in recent years. This scientific research

has demonstrated that it is technically feasible to produce alternative fuel using

microalgae, though this approach is not economically suitable for industrial production

[19-22]. In a literature review on the processing of microalgae using a thermochemical

pathway carried out by Raheem et al. [23], it was confirmed that HTL of microalgae

was a promising technology to produce high-quality alternative fuel. There are two

key methods for obtaining biofuel from microalgae. The first is solvent extraction

followed by transesterification to produce fatty acid methyl esters (i.e. FAME

biodiesel). The second method is a thermochemical process, HTL, to produce

biocrude. The main benefits of liquefaction are that many different products can be

extended and that drying of the biomass is not required. In contrast, solvent-extraction-

processed biofuel contains only FAME and uses dry biomass. HTL biocrude does not

depend on the lipid content of the feedstock because the whole biomass is converted

into biocrude. Conversely, solvent extracted then transesterified biofuel depends on

the lipid content of the biomass. Solvent extraction is a low-pressure process but a

high-cost solvent is required, while HTL is a high-pressure process.


Waste-tyre disposal is a growing problem across the world [24]. Most people are

aware that ELTs are a significant environmental hazard, but few know the extent of

the problem. It is reported that Australians generate over 51 million ELTs each year

[25], which is equal to 0.68 million tons [26]. Recently an Australian company, GDT,

developed a process to convert whole waste tyres into tyre oil as an alternative to diesel

fuel [18]. The technology reduces the full tyres to their original constituents of carbon,

steel, and tyre oil. Around one third of the total mass of waste tyres is converted to tyre

oil. The Australian Bureau of Resource and Energy Economics [27] has reported that

Australia’s petroleum consumption has reached about 64 billion litres per annum with

nearly 70% used for the transport sector in 2013. Diesel fuel holds the largest share,

which is 41% [28]. It is estimated that around 1% of diesel fuel could be replaced by

waste-tyre oil in Australia.

The physicochemical properties of biofuels are important parameters with

respect to the quality of fuels and their application. The physical properties vary with

chemical composition, including the carbon-chain length and the degree of

saturation/unsaturation. Other factors that affect fuel suitability for a conventional

engine include chemical composition, molecular structure, Cetane Number (CN), acid

value and sulphur content. Moreover, these fuel properties affect the engine performance

and exhaust emission results. Several studies have shown that fuel properties can

significantly affect engine exhaust emissions. There is widespread agreement that no

single factor is responsible for alternative fuel engine performance and the character

of exhaust emissions. Microalgae alternative fuels are considered to be a first fuel in

this research.

The chemical composition and physical properties of microalgae biocrude

produced using HTL methods were found to be different to that of diesel and biodiesel.

Therefore, the biocrude required further processing (i.e. upgrading) to improve its

quality by reducing undesired components. The authors carried out research to produce

a microalgae HTL surrogate fuel based on various chemical compounds, which gave

a GC-MS analysis of the biocrude. This research covered the selection of different

chemicals of microalgae HTL and their percentages based on the target fuel properties.

The physiochemical properties of the target fuels were considered as the design

parameters and the percentile ranges for different groups of chemicals were based on

previous research or knowledge gained from experience. The reference chemicals


were selected from microalgae HTL biocrude chemicals. The selected chemicals were

then blended in different proportions and measured against the design properties.

Those properties were compared with the target fuels and optimised by changing the

input parameters, for example, the percentages of different chemicals. Finally, a

surrogate fuel was prepared to test in an internal combustion (IC) diesel engine. On

the other hand, the properties of tyre oil were tested and were found to be similar to

diesel fuel in higher-heating value (HHV), viscosity, density, and CN. Before

conducting the experimental studies, a careful fuel analysis was carried out. It is

broadly accepted that fuel properties influence fuel-spray characteristics, fuel

evaporation, the formation of fuel droplet size, the distribution of fuel atoms, and,

therefore, the exhaust emissions. These features are determined by the physiochemical

property of the fuel.

However, the HTL technology required to generate alternative fuel from

microalgae and the feedstock waste-tyre oil is still in its early stages of development.

It appears that there is a considerable amount of research on microalgae biofuel

production and its use in engine tests, but none using a surrogate based on microalgae

HTL biocrude for engine tests. Similarly, there is little research on waste-tyre oil using

a pyrolysis process and its application in diesel engines and no research testing GDT-

tyre oil in turbo-charged diesel engines. This research project investigates the effects

on engine performance and exhaust emissions of adding both tyre oil and microalgae

surrogate to diesel. A more thorough investigation of HTL microalgae biocrude and

waste-tyre oil properties, as well as their effect on engine performance and emissions,

should also be researched to establish both fuels as an alternative fuel option.

1.2 RESEARCH OBJECTIVES

The initial concern of this research is the thermochemical conversion of wet

microalgae and dry waste tyre to an alternative fuel, with the help of HTL and pyrolysis

technology, respectively. It is important to identify the physicochemical properties of

alternative fuels as their quality determines their application. The physicochemical

properties of HTL microalgae alternative fuel are not suitable for a transport diesel

engine. As a result, a new surrogate fuel was developed, based on the microalgae HTL

chemical compounds that could be used for diesel engines. Conversely, the

physiochemical properties of waste-tyre pyrolysis oil was measured and found to be

suitable for use in a diesel engine. Following this, the HTL microalgae surrogate fuel


and tyre pyrolysis oil, respectively, were mixed with diesel fuel, and an experiment

was conducted in the internal combustion engine. The engine performance and exhaust

emissions of the blended microalgae HTL alternative fuel and tyre pyrolysis fuel were

compared separately with regular diesel fuel.

Objectives: This project aimed to achieve the following objectives

1. To investigate the thermochemical conversion process for wet microalgae

and dry-waste-tyre feedstock and identify key process parameters, which

affect biocrude properties.

2. To determine the critical physicochemical properties of microalgae biocrude

from the HTL process and compare them with those of FAME and petroleum

diesel.

3. To develop a surrogate fuel based on a microalgae HTL chemical compound

and investigate its diesel engine performance and exhaust emissions.

4. To investigate the physicochemical properties of waste-tyre oil and

investigate diesel engine performance and exhaust emissions, compared to

diesel fuel.

1.3 RESEARCH QUESTIONS

Four research questions (see below) were formulated from gaps in the research based

on thermochemical conversion, physicochemical properties of fuels, engine

performance and exhaust emissions. Each of these questions are carefully examined

and addressed in the remaining Chapters of this thesis.

Q1. What thermochemical conversion methods are convenient for a wide range (wet

to dry) of second-generation alternative fuel feedstocks?

In most cases, second-generation feedstock is processed differently to first-

generation biofuels using a thermochemical conversion. Thermochemical conversion

is the use of heat, with or without the presence of oxygen, to convert various feedstocks

into other forms of energy. Among different thermochemical conversion processes,

pyrolysis and hydrothermal conversion are most used for their easy of operation. Both

processes are used to transform the component into fuels along with other related HC-


based products. In this research, the authors experimentally investigated the

conversion of wet microalgae to biocrude using HTL and waste tyre to an alternative

fuel using a pyrolysis process.

Q2. What are the complex physicochemical properties of microalgae-obtained HTL

and how do they compare with FAME and diesel?

A microalgae HTL process for biofuel production is only a recent development

in the field of alternative fuel research. Researchers have been working with

microalgae to produce a biofuel using a solvent-extract-derived then

transesterification. More recently, researchers have been using a HTL process to

produce biofuel from microalgae. However, the physicochemical properties of

microalgae liquefaction biofuel need to be investigated. This biofuel can be used in IC

engines and has the potential to significantly change exhaust emissions. The engine

performance and exhaust emission results should be compared with diesel to modify

the HTL microalgae bio-fuel.

Q3. What properties of HTL microalgae biocrude create problems for the engine

operation and how can a surrogate be produced using selected chemical compounds

of microalgae HTL to overcome the problem and improve engine performance and

exhaust emissions?

The major challenge remaining is being able to use hydrothermal liquefied

microalgae biofuels in diesel engines. Being an alternative fuel in the transportation

sector, it provides the easiest and most crucial solution for environmental problems as

it does not require any engine modifications and reduces greenhouse gas (GHG)

emissions substantially. However, the physicochemical properties of microalgae HTL

alternative fuels are not suitable for transport engines. As a result, a new surrogate fuel

was invented using a higher percentage of some of the chemical compounds of the

microalgae HTL alternative fuel. To achieve an efficient surrogate fuel that produces

fewer emissions and more power without hindering engine operation, the

physicochemical properties must be modified.


Q4. What physicochemical properties of GDT/pyrolysis tyre oil affect the diesel

engine performance and exhaust emissions?

Globally, waste-tyre disposal is a growing problem. Most people are aware that

ELTs are a significant environmental hazard, but few know the extent of the mass that

is generated each year. It has been reported that each year over one billion waste tyres

are generated worldwide and this will increase to 1.5 billion by 2020, which is a huge

problem in terms of waste disposal. Therefore, waste-disposal-tyre-to-fuel

technologies offer a very promising solution for both issues. The next major challenge

is to test current vehicle engine performance and exhaust emissions using pyrolysis

tyre oil.

1.4 RESEARCH APPROACH

This experimental research is a comparative study of thermochemical

conversion, alternative fuel physicochemical properties and a diesel engine test

between wet microalgae and waste-tyre feedstock. These experimental results are then

compared with the limited previous studies available. Some available studies focus on

microalgae HTL surrogate fuel, though no studies can be found that utilise waste-tyre

oil. The approach used in this study is as follows:

Experimentally investigate wet microalgae and waste-tyre conversion to

alternative fuel using HTL and pyrolysis as a thermochemical conversion

method.

Analyse physicochemical properties of both types of fuel and compare with

regular diesel fuel to develop an alternative fuel for diesel engines.

Develop a new surrogate fuel based on microalgae HTL chemical compounds

and investigate CI engine performance and exhaust emissions.

Investigate engine performance and exhaust emissions with waste-tyre oil and

compare the results with diesel fuel.

The objective of this research is primarily to establish suitable feedstock and

appropriate conversion technology for industrial production. Concurrently, the

physicochemical properties of the fuel are analysed with the intention of investigating

its use as an alternative transport fuel, which would reduce exhaust emissions. The

conceptual flow chart of this research is shown in Figure 1.1.


Chapter_1: Introduction

Thesis aim: Experimental investigation of thermochemically derived fuels in a diesel engine

Chapter_3: Literature review on hydrothermal

liquefaction of microalgae

This chapter related to objective 1 and paper 1.

Chapter_5: HTL Experiments

Microalgae HTL biocrude and its property analysis


Chapter_6 : Investigation of microalgae HTL fuel

effects on diesel engine performance and exhaust

emissions using surrogate fuels


Chapter_4: Literature review on paralysis waste

tyre to oil

Chapter_7 : Investigation of diesel engine

performance and exhaust emissions using GDT

tyre oil

This chapter related to objective 4and paper 4.

Chapter_8

Conclusions and Recommendations

Chapter_2: Research contribution

Current state of knowledge of microalgae HTL biocrude and waste tyre oil

First Stream Second Stream

IC engine testing with microalgae surrogate and waste tyre oil

Figure 1.1: Conceptual flow chart of dissertation.

Chapter 2: Contribution of thesis 30

Chapter 2: Contribution of thesis

This thesis is prepared in the form of a thesis for publication, with a total of eight

chapters. It comprises two streams, as shown in Figure 1.1. The first stream is based

on microalgae and the second is based on waste tyres. The background, motivation,

and research questions for this thesis are described in Chapter 1. The contribution of

the research and conceptual structure are presented in Chapter 2. Chapters 3, 5, and 6

are part of the first stream of the thesis and Chapters 4 and 7 are part of the second

stream of the thesis. All chapters are organised as per the conceptual chart shown in

Figure 1.1. An overview of Chapters 3–8 is included below.

Chapter 3, first stream: Chapter 3 begins with a literature review of microalgae

conversion into alternative fuel using two different methods, which the research

community has thus far focused on. These are solvent extraction and transesterification

to produce FAME biodiesel, and HTL to produce biocrude. The resulting differences

in biofuel physicochemical characteristics not only affect engine performance and

emissions but also engine selection. Most engine research relating to microalgae has

been carried out on high-speed diesel engines to investigate the performance and

exhaust emissions of FAME, whereas the HTL literature has mostly presumed

biocrude would be upgraded for such engines. This literature review provides a

detailed explanation of the conversion of microalgae into alternative fuel and its

application in a diesel engine.

This Chapter has been published as a journal paper in the ‘Journal of Renewable and

Sustainable Energy Reviews’, entitled, “Performance and exhaust emissions of diesel

engines using microalgae FAME and the prospects for microalgae HTL biocrude”,

paper 1, which is related to research objective 1.

Chapter 4, second stream: Chapter 4 introduces waste tyres as a source of alternative

fuel and explores the application of that fuel in a diesel engine. This Chapter presents

literature reviews on waste tyre statistics and their recycling status around the world.

It also reviews the thermochemical conversion of waste tyres to tyre oil by using a

pyrolysis process. Finally, the Chapter explores variances in the physicochemical


properties of waste-tyre oil due to the conversion process, which can affect diesel

engine performance and exhaust emissions.

Chapter 5, first stream: This chapter describes the experimental measurements of

physicochemical properties for a HTL biocrude from a high-growth-rate microalga,

Scenedesmus sp., using a large-batch reactor. HTL is well suited to wet biomass (such

as microalgae) as it greatly reduces the energy requirements associated with

dewatering and drying. Furthermore, batch reactors overcome issues with feeding,

despite the high pressure required (200 bar), and can change feedstocks easily. The

HTL literature mostly reports on work using very small-batch reactors, which are

preferred by researchers, so there are few experimental and parametric measurements

for the physical properties of biocrude in large-batch reactors, such as HHV, viscosity

and density. During this study, a difference between the traditional calculated values

and the measured values was noted.

This Chapter has been published as a journal paper in the ‘Journal of Energies’,

entitled, “Experimental investigations of physical and chemical properties for

microalgae HTL biocrude using a large-batch reactor”, paper 2, which is related to

research objective 2.

Chapter 6, first stream: Chapter 6 focuses on engine performance and exhaust

emission testing using a surrogate fuel of microalgae HTL. This Chapter provides the

details of surrogate fuel preparation, physicochemical properties analysis and engine

testing. The performance of microalgae surrogate alternative fuel in different blends is

compared with petroleum diesel. The gaseous emissions of all surrogate alternative

blends are also compared with petroleum diesel. This Chapter provides unique

information on microalgae surrogate alternative fuel engine performance and exhaust

emissions. In Chapter 3, it was noted that no engine tests performed with microalgae

surrogate fuel had been found. Therefore, this Chapter holds great value in the field of

alternative fuel research.

This Chapter will be submitted as a journal paper in the ‘Journal of Industrial Crops

and Products’, entitled, “Investigation of the effects of microalgae HTL surrogate fuel

on diesel engine performance and exhaust emissions”, paper 3, which is related to

research objective 3.

Chapter 2: Contribution of thesis 32

Chapter 7, second stream: This chapter focuses on engine performance and exhaust

emissions testing, using waste-tyre oil provided by GDT Corporation Ltd, Australia.

Globally there is a significant volume of ELTs that can be converted into tyre oil using

a thermochemical conversion process. Chapter 4 presents a detailed review of waste

tyre statistics across the world. The physiochemical properties of the tyre oil are similar

to diesel fuel and miscible with diesel in any blend ratio. The experimental results

showed that there was no change in engine performance using 10% and 20% blend

tyre oil as well as showing a reduction in exhaust emissions. It was the first time this

fuel has been used in a diesel engine test and analysed as an alternative fuel.

Consequently, this Chapter also makes a valuable contribution to this field of fuel

research.

This Chapter will be submitted as a journal paper in the ‘Journal of FUEL’ entitled,

“Engine performance, combustion and exhaust emissions using diesel and biodiesel

with tyre oil”, paper 4, which is related to research objective 4.

Chapter 8: Chapter 8 concludes the thesis with a summary of the original

contributions and proposes possible directions for future research.

Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL

biocrude 33

Chapter 3: Literature review on diesel

engine performance using

microalgae FAME and the

prospects of HTL biocrude

Title: Performance and exhaust emissions of diesel engines using

microalgae FAME and the prospects for microalgae HTL biocrude

Farhad M. Hossain*1, 2, Thomas J. Rainey1, 2, Zoran Ristovski1, 2, 3,

Richard J. Brown1, 2, 3

1Biofuel Engine Research Facility, Queensland University of Technology (QUT),

Brisbane, Queensland 4001, Australia

2School of Chemistry, Physics and Mechanical Engineering, QUT

3 International Laboratory for Air Quality and Health, QUT

* Corresponding author

Contact: Md Farhad Hossain

Email: [email protected], [email protected]

Postal address: GPO Box 2432, 2 George St, Brisbane, QLD 4001, Australia

mailto:[email protected]

mailto:[email protected]


Statement of contribution of Co-Authors for this publication

The authors listed in the table below have certified that:

1. They meet the criteria for authorship in that they have participated in the conception, execution, or

interpretation, of at least that part of the publication in their field of expertise;

2. They take public responsibility for their part of the publication, except for the responsible author who

accepts overall responsibility for the publication;

3. There are no other authors of the publication according to these criteria;

4. Potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or publisher of

journals or other publications, and (c) the head of the responsible academic unit, and

5. They agree to the use of the publication in the student’s thesis and its publication on the Australasian

Research Online database consistent with any limitations set by publisher requirements.

Title and status: Performance and exhaust emissions of diesel engines using

microalgae FAME and the prospects for microalgae HTL biocrude, (Published at

Renewable and Sustainable Energy Reviews)

Contributor Statement of contribution

Md Farhad Hossain Candidate

Design concept of the article, wrote the manuscript and acted as the

corresponding author.

Signature

Date

Richard J. Brown Principal Supervisor

Professor Richard Brown is a mechanical engineer, he is a leading expert

in thermodynamics and environmental fluid mechanics, particularly in

relation to internal combustion engine performance and emissions.

Design concept, reviewed material related to engine performance and

edited the manuscript.

Zoran Ristovski Associate Supervisor

Professor. Zoran Ristovski is a physicist who works at Queensland

University of Technology as one of the leading researchers on vehicle

emissions with a special focus on particulate vehicle emissions.

Reviewed the manuscript in the section of engine exhaust emissions.

Thomas J. Rainey Associate Supervisor

Dr. Thomas Rainey has 15 years of industrial and research experience in

biomass processing particularly in pulp and paper and sugar processing.

His research focuses on bioenergy and related value-added products.


biocrude 35

Design concept, reviewed and edited the manuscript in the section related

to biofuel production.

Principal Supervisor Confirmation

I have sighted email or other correspondence from all Co-authors confirming their certifying authorship.

Professor Richard J. Brown

Name Signature Date


Abstract:

Microalgae have attracted recent attention due to their potential as a second-

generation biofuel. This article compares and contrasts two key methods the research

community is focussing on to obtain biofuel from microalgae, namely solvent

extraction followed by transesterification, to produce fatty acid methyl esters (i.e.

FAME biodiesel), and hydrothermal liquefaction (HTL) to produce biocrude. The

resulting differences in biofuel physicochemical characteristics not only affect engine

performance and emissions but also engine selection. Most engine research relating to

microalgae has been carried out on high-speed Compression Ignition (CI) engines to

investigate the performance and exhaust emissions of FAME, whereas the HTL

literature has mostly presumed biocrude would be upgraded for similar engines.

However, growing awareness of the significant contribution of shipping emissions to

public health brings into focus alternatives to heavy-fuel oil (HFO) for low-speed CI

(marine) engines. Microalgae FAME contains about 10.5–11 % (wt.) oxygen and

36.2–39.2 MJ/kg calorific value, (10–15% lower than for petroleum diesel). When

tested in high-speed CI engines, microalgae FAME generally decreases particulate

emissions but there is a small penalty in terms of engine power owing to the high

oxygen content and lower higher-heating value (HHV). Conversely, biocrude obtained

by HTL for green freshwater microalgae contained 10–11% (wt.) oxygen, 4–8% (wt.)

nitrogen and 32–35 MJ/kg calorific value (20–27% lower than for petroleum diesel).

HTL biocrude would be expected to reduce exhaust emissions for low-speed marine

CI engines compared to HFO, especially soot emissions due to their very low sulphur

content, although NOx emissions may increase. HTL biocrude may reduce the engine

performance in terms of output power compared to HFO due to the higher oxygen

content and lower HHV. The aim of this article is to review and compare microalgae

FAME and HTL biocrude and their suitability for high- and low-speed CI engines in

terms of engine performance and emissions.

Keywords: Biodiesel, microalgae, HTL, FAME, CI Engine, emissions


biocrude 37

3.1 INTRODUCTION

Renewable biofuel has become a key issue in the modern world due to fossil fuel

reserve depletion, increasing fuel prices and exhaust emissions [29]. Compared to

diesel, biofuel has a generally favourable combustion emission profile, including

lower emissions of carbon monoxide (CO), particulate matter and unburned

hydrocarbons [30, 31], however, NOx may increase. Microalgae have recently

received a lot of attention to produce biofuel as a renewable feedstock because of its

potential for mass production on non-arable land [2, 10, 32-35]. They are also not

highly compatible with bioethanol, which has been the focus of much research in

recent years. Although numerous conversion technologies exist, biofuel properties

vary significantly, even when the same feedstock is used [32, 36-38]. With regards to

using microalgae to make biofuel for Compression Ignition (CI) engines (i.e. diesel

engines), there has been significant recent interest in two conversion technologies.

Firstly, microalgae can be solvent extracted to recover lipids, which

subsequently undergo a traditional transesterification reaction to produce fatty acid

methyl esters (i.e. FAMEs)—normally known as biodiesel. However, for microalgae,

the raw material should be dried (at considerable expense) prior to the solvent

extraction. Microalgae FAMEs have a large variance in chemical composition due to

the feedstock [6, 35, 39]. Hussain et al. [40] tested lipid profiling and corresponding

biofuel properties of Mortierella isabellina microalgae using different drying and

extraction methods and found that differences in chemical composition of the lipids

were obtained for the same species [6, 41-43]. Islam [10] found that the

physicochemical properties of the FAME also varied with microalgae species.

A second method undergoing intensive research is HTL, which can utilise wet

biomass to produce a biocrude [44-47]. HTL converts biomass into gas, liquid and

solids similar to pyrolysis [48], but operates at a higher pressure (up to 300 bar) and at

a lower temperature between 250 °C and 350 °C [47, 49]. There have been some

investigations into converting microalgae into biofuels via HTL [33, 50-54]. HTL has

been investigated with a wide range of microalgae feedstocks, including laboratory

and commercially grown strains of Botryococcus braunii [55], Spirulina and

Tetraselmic sp. [32, 47]. Jena et al. [49] tested Spirulina platensis using HTL for

biocrude production and found the operating conditions varied the chemical

composition. The energy balance and CO2 mitigating effect of liquid fuel production


from microalgae by HTL has been reported by Sawayama et al. [56]. Eboibi et al. [47]

found that up to 65 % (wt.) biocrude oil could be obtained by HTL [47]. However,

their experimental work found that the HTL biocrude properties were dissimilar to

diesel and biodiesel and closer to that of HFO, which is used for low-speed marine

diesel engines. Consequently, the target application for HTL biocrude needs further

investigation depending on the physicochemical properties of the fuel [57].

There are two types of diesel engines high speed and low speed. The main

difference is fuel type. High-speed diesel engines use low-density and cleaner fuel (e.g.

diesel), whereas low-speed diesel engines use high-density and impure fuels (e.g.

HFO/HTL). High-speed diesel engines are used for vehicles and portable power

generators and are run using diesel or biodiesel. Conversely, low-speed diesel engines

are used for industrial power plants, marine ship engines, and are run by various grades

of HFO. However, most researchers have only used high-speed diesel engines to

investigate various biodiesel influences on performance and emissions [5, 7, 57]. The

authors couldn’t find any publications relating to low-speed diesel engines tested using

a bio-based alternative to HFO for measuring engine performance and emissions.

This review aims to compare the relative engine performance and emissions of

FAME and HTL biocrude from microalgae for high-speed and low-speed engines,

based on physicochemical properties. This requires a brief description of the

conversion technologies to set the context.

3.2 MICROALGAE BIOMASS TO BIOFUEL CONVERSION

TECHNOLOGIES

Microalgae to biofuel conversion technologies can be divided into two main

processes: biochemical and thermochemical. Thermochemical processes can be

subdivided into gasification, pyrolysis and liquefaction [58]. The microalgae biomass

energy conversion technique is shown in Figure 3.1. However, microalgae biomass

has high water content (80–90%) meaning that not all conversion processes are

suitable [59]. This article focusses on technologies suitable for diesel engines.


biocrude 39

Biochemical

conversion

Thermochemical

conversion

Fermentation Transesterification Gasification Pyrolysis

Raw microalgae

Dry

microalgae

Solvent-

extraction

Wet

microalgae

Hydrothermal

liquefaction

Thermochemical

conversion

Figure 3.1: Classification microalgae conversion processes [60].

3.2.1 Solvent extraction and transesterification to produce FAME

Solvent extraction of lipids from microalgae biomass transfers crude lipids from

a liquid phase to a second, immiscible phase. Possible solvents include benzene,

ethanol, hexane or ethanol-hexane mixtures [35, 60, 61]. The most widely used solvent

is hexane, due to its lower cost, ready availability, low toxicity, density and boiling

point [62, 63]. Extracted lipids are dissolved in the solvent and form a solution separate

to the cell debris and hydrophilic compounds [64, 65]. This is due to oil being highly

soluble in the organic solvents used in this process, which is shown in Figure 3.2. Non-

polar solvents typically are better at extracting non-polar lipids whereas polar materials

are typically extracted better by polar solvents. Therefore, a solvent with similar

polarity to that of the crude lipids being extracted is desirable. This connection between

polar compounds minimises the co-extraction of non-lipid contaminants (protein and

carbohydrates) [66]. Higher lipid yields can be achieved by either disrupting cell walls

before adding the solvent or using a combination of solvents such as hexane (non-

polar), methanol (polar) and water [62]. Contamination is a major obstacle when using

organic solvents, as pigments can be extracted into the product.


Dry biomass

Extraction vessel

(Solvent extraction)

Filtration

Distillation

of solvent

Raw oil

Biofuel

Transesterification

Figure 3.2: Solvent-extraction and transesterification SET process.

The extracted lipid is then converted into biodiesel via transesterification.

Transesterification is a chemical reaction between triglycerides and alcohol in the

presence of a catalyst (usually basic) to produce biofuel [67]. FAME can be used

directly in a conventional high-speed CI (i.e. diesel) engine.

3.2.2 HTL to produce microalgae biocrude

HTL is a thermal depolymerisation method to convert wet biomass into biocrude

at elevated temperature and pressure [68, 69]. HTL has been effectively carried out at

both sub-critical and super-critical conditions but the problem for high-speed diesel

engines is that the chemical composition and physical properties of HTL biocrude are

not similar to that of diesel and biodiesel [47, 70, 71]. HTL produces biocrude with

higher oxygen and nitrogen content compared to diesel. In addition, HTL biocrude

contains inorganic salts and metals, which pose challenges with traditional refining

process [32, 55, 72]. Therefore, the biocrude requires further processing (i.e.

upgrading) to improve quality by reducing the levels of these undesired components.

The retention times in the reactor are usually in the range 5–120 min. Figure 3.3 shows

the HTL conversion process using dichloromethane (DCM) as the solvent.


biocrude 41

As mentioned, liquefaction can occur with high moisture content feedstocks [59,

60]. However, this can result in high energy costs. The formulation of additives could

help to improve process economics [60].

HTL process

Residues

Liquid phase

DCM phaseAqueous

phase

Bio-crude

Filtration

Evaporation

Extraction

Wet biomass

Figure 3.3: HTL process and product separation [33].

3.2.3 Comparison of biomass to biocrude conversion technology

The main benefits of liquefaction are that many different products can be

produced and that drying of the biomass is not required. Solvent-extraction-processed

biofuel contains only FAME and is produced from dry biomass. HTL biocrude doesn’t

depend on the lipid content of the feedstock because the whole biomass is converted

into biocrude and so conversion yields are high. Conversely, solvent-extracted biofuel

depends on the lipid content of the biomass. Solvent extraction is a low-pressure

process but high-cost solvent is required, whereas HTL is a high-pressure process that

produces a much broader range of chemicals and requires further refining to produce

suitable physicochemical properties for high-speed diesel engines. For low-speed

diesel engine application, HTL biocrude is closer to HFO with considerably lower

sulphur content and so relatively less refining is required.


There have been several studies investigating the price of microalgae biodiesel

with prices from studies found to be in the range of $0.63/L (best-case scenario with

highly optimistic lipid yields) [21] to $2.60/L [19]. $1.50/L was found for a multi-

output system including fertiliser co-production [22]. In contrast, there have been very

few techno-economic investigations exploring the cost of microalgae HTL biocrude

production.

The physicochemical properties of biofuels are important parameters with

respect to the quality of fuels and their application. The physical properties vary with

chemical composition including the carbon-chain length and the degree of

saturation/unsaturation [7, 38, 43, 73]. Other factors that affect fuel suitability for a

conventional engine include chemical composition, molecular structure, cetane

number (CN), acid value and sulphur content. Moreover, these fuel properties affect the

engine performance and exhaust emission results [57]. Several studies have shown that

fuel properties can significantly affect engine exhaust emissions [57, 73-80]. There is

widespread agreement that no single factor is responsible for biodiesel engine

performance and the character of exhaust emissions. Table 3.1 shows the influence of

fuel properties on heavy-duty diesel engine exhaust emissions.

Table 3.1: Influence of fuel properties on heavy-duty diesel emissions [57, 81, 82].

Fuel properties influence HC CO NOx PM

Reduce density ↑↑ ↑ ↓ ↓↓

Increase CN ↓↓ ↓↓ ↓ 0

Increase oxygenate * ↑ -- 0 ↓

Reduce sulphur 0 0 0 ↓↓

Legend: ↑↑, ↓↓- large effect, ↑, ↓-small effect

* - Tentative results, require confirmation by further work

HC: Hydrocarbon , CO: Carbon monoxide, NOx: Nitrogen oxide,

PM: Particulate matter

McCormick et al. [83] concluded that the molecular structure of biofuel has a

direct relationship with emissions. The effect of biofuels on high-speed diesel engine

emissions has been investigated by Song et al. [84], who found reduced emissions

compared to diesel. CN is measured based on the ignition and combustion quality of


biocrude 43

the fuels. Higher CN fuels tend to increase power output and reduce emissions. The

density of biofuel is generally higher than for conventional diesel fuel. The viscosity

and surface tension of the fuels act to reduce atomisation. Additionally, the raw

material greatly influences their physicochemical properties.

3.2.4 FAME biofuel properties

The purified biofuel obtained from microalgae oil transesterification (i.e.

FAME) has been tested for physicochemical properties by several researchers [3].

Table 3.2 shows some of the chemical and physical properties of microalgae biofuel,

standard biodiesel and diesel properties; many properties are similar. The CN of

FAME microalgae biofuel is close to ASTM D6751-12 diesel. Lower CN affects

ignition delay and can reduce engine performance. The kinematic viscosity and density

of the microalgae biofuel is higher than standard biodiesel and diesel fuel, which can

affect atomisation, penetration and ignition in the combustion chamber. Basically,

those properties reduce engine performance. Islam et al. [3] experimentally

investigated common-rail heavy-duty high-speed diesel engine performance with

microalgae FAME. They found brake-specific fuel consumption (BSFC) for

microalgae FAME was higher compared to diesel and brake thermal efficiency (BTE)

was lower than diesel [3]. Due to higher fuel density, BSFC is higher for microalgae

biofuel and BTE is lower due to its lower calorific value [3]. However, the chemical

composition and structure of microalgae biofuel is different compared to that of diesel

fuel. Microalgae biofuel contains compounds with higher carbon-chain length than

diesel. A key difference between microalgae FAME and diesel is the presence of

oxygen. The chemical properties affect the combustion inside the engine cylinder and

reduce exhaust emission from microalgae biofuel [3, 85-87].


Table 3.2: Solvent-extraction microalgae biofuel properties [3, 86, 87].

Fuel Properties Unit

Standard Biodiesel [82]

Petroleum

Diesel ASTM

D6751-12

EN 142

14:2012

Microalgae

FAME [3]

CN 47 51 46.5 50–53.3

Kinematic

viscosity@40 ˚C mm2/s 1.9–6.0 3.5–5.0 5.06 2.62–2.64

Density @15 ˚C kg/L -- 0.86–.90 0.912 0.82–0.84

HHV MJ/kg -- -- 39.86

LHV MJ/kg -- -- 37.42 44

Acid value mg KOH/g 0.50 0.5 max 0.14 0

Flash point (close

cup) ˚C 93 101 95 71

Sulphur content mg/kg 15 ppm 10 max 7.5 5.9

Cloud point ˚C Report Report 16.1 4

Lubricity @60 ˚C mm -- 1 max 0.136 0.406

Oxygen content wt.% -- -- 10.47 0

Hydrogen content wt.% -- -- 11.12 13.86

Carbon content wt.% -- -- 78.41 86.13

Nitrogen content wt.% -- -- 0 0

3.2.5 HTL biocrude properties

HTL biocrude produced from various kinds of biomass including microalgae is

a dark, highly viscous and energy-dense liquid [23, 50, 88]. Its energy content is 70–

95% of that for diesel fuels and is similar to HFO [54, 89]. Typical chemical

components are carbon, hydrogen, oxygen and nitrogen. The nitrogen content is a key

difference to other biofuels. The biocrude contains a carbon content of usually 70–

75%, an oxygen content of 10–16% and 3–7% nitrogen, as shown in Table 3.3. The

oxygen contents of microalgae biocrude is significantly lower than the oxygen content

in the original microalgae cells. The biocrude components change with respect to

experimental condition and biomass feedstocks [51, 89].

The physicochemical properties of biocrude are strongly dependent on biomass

feedstock and conversion technology. It is a mixture of compounds including

aromatics, oxygenated and nitrogenised species, straight carbon chains of varied

molecular weights [90]. The biocrude’s chemical components are affected by the

processing conditions including temperature, pressure and sample-slurry

concentration. A major problem related to HTL biocrude is its high N content, usually


biocrude 45

in the vicinity of 3–7%, which can lead to high NOx emissions upon combustion [51,

67]. The calorific value of the biocrude is lower compared to diesel because the oxygen

content and the carbon-to-hydrogen ratio of biocrude are lower. The calculated

calorific value based on chemical composition using the Dulong formula [91] is shown

in Table 3.3 for different microalgae biocrude. However, the chemical and physical

properties of microalgae biocrude differ significantly compared to FAME microalgae

biofuel.

Table 3.3: Elemental analysis and HHV of microalgae HTL biocrude.

HTL biocrude

(on dry basis)

Operating

conditions Fuel Properties

Refe-

rence Temp.

(°C)

Time

(min)

Chemical composition

(wt. %) HHV

(MJ/kg) C H N O

Scenedesmus sp. 350 60 75.6 10.1 3.97 10.3 37.4 [92]

Enteromorpha

prolifera 370 40 77.9 9.6 5.6 6.9 39.4 [51]

Enteromorpha

prolifera 300 30 64.5 7.7 5.4 22.4 30.8 [50]

Sargassum

patens C. Agardh 340 10 64.6 7.4 2.5 25.5 30.4 [93]

Laminaria

saccharina 350 15 82.0 7.1 4.9 6.0 37.4 [72]

Saccharina sp. 340 87 79.4 8.0 4.1 8.5 37.5 [53]

Chlorella

pyrenoidosa 350 60 75.1 9.9 7.3 7.7 38.1 [94]

Lemna sp. 350 30 72.1 7.8 4.6 15.5 32.8 [95]

3.2.6 FAME and HTL biofuel properties

The FAME microalgae biodiesel is a deep-brown low-viscosity fuel, whereas

microalgae HTL biocrude is dark high-viscosity oil. The chemical composition,

compound structure and carbon-chain length differ significantly. Islam et al. [3]

performed a detailed investigation with FAME microalgae biodiesel as shown in Table

3.4. The chemical composition was found to be similar to standard biodiesel. In

contrast, the properties of microalgae HTL biocrude are similar to HFO, which as

shown in Table 3.6. FAME microalgae biodiesel is suitable for high-speed diesel

engines including buses, tractors, cars and similar vehicles while HTL biocrude is

suitable for low-speed diesel engines, such as large marine ship engines and large

electric generators.


Table 3.4: FAME versus HTL microalgae biofuel properties in comparison with

conventional diesel and HFO.

Fuel Properties Unit

Microalgae

(FAME)

[3]

Diesel

[3, 96]

Microalgae

(HTL)

[92]

HFO

(selected)

[97]

Viscosity@40 ˚C mm2/s 5.06 2.64 70.7–73.8 743.4

Density @15 ˚C kg/L 0.912 0.84 0.97–1.04 0.99

HHV MJ/kg 39.86 44 30–35 ---

Sulphur content mg/kg 7.5 5.9 0 2030

Oxygen content wt% 10.47 0 10.33 1.64

Hydrogen content wt% 11.12 13.4 10.14 9.63

Carbon content wt% 78.41 86.5 75.56 85.87

Nitrogen content wt% 0 0 3.97 0.46

3.3 ENGINE PERFORMANCE AND EMISSIONS

HTL biocrude could be used in low-speed diesel engines, which will result in a

significant change to exhaust emissions. The engine performance and exhaust

emissions results should be different to microalgae FAME and existing biofuels [3,

98]. So, one of the options is to use HTL biocrude in low-speed diesel engines with

little or no modification. To achieve an efficient biofuel that produces less emissions

and more power without hindering engine operation, the physicochemical properties

must be optimised.

Diesel engine performance parameters for both high-speed and low-speed

engines include engine power, torque, BSFC and BTE [3, 5, 99]. It is commonly

argued that biodiesel slightly reduces the power output and torque compared to diesel

due to its lower calorific value [3, 57, 73, 100]. Utlu and Kocak [101] found around

4.5% and 4.3% reductions in power and torque, respectively when used waste cooking

oil methyl ester, compared to diesel. Hansen et al. [102] found that lower calorific

value is not the only factor that reduces the power and torque, but density and viscosity

also have significant effects on engine output power and torque. For example, higher

viscosity and density of biofuels causes an increased amount of fuel injected into the

combustion chamber, which can lead to an increase in power [103]. Conversely, lower

atomisation due to higher viscosity can sometimes reduce combustibility of the fuel

and reduce power [103, 104]. Furthermore, higher lubricity of biodiesel will reduce

the frictional loss and consequently recover engine power and torque [105].


biocrude 47

Researchers found no noticeable difference for 5% rapeseed biodiesel blend usage

results in terms of power and torque, compared to diesel [106, 107]. It is also reported

that the BSFC of biofuel is increased, compared to diesel [107]. In a high-speed diesel

engine running with rapeseed oil and its blends, Buyukkaya [106] found that BSFC

increased by up to 11%, compared to diesel. In summary, it was proposed that power

and torque were not only dependent on feedstock and fuel properties, but also on the

engine type and operating conditions, such as engine speed, load, injection timing and

injection pressure [104, 108].

Diesel engine emissions contain pollutants that adversely affect human health

and the environment. Diesel engine emission regulations have included NOx, PM and

CO since the adoption of the first emission standards. More recent regulations also

introduced emission limits on CO2 and other greenhouse gases. The use of renewable

biofuel plays a role in energy security issues by reducing dependence on imported

petroleum products, which are being depleted rapidly [109, 110]. Despite this, other

factors are having an influence on the uptake of biofuel, such as the need to mitigate

global warming and to reduce exhaust emissions [85, 111].

3.3.1 Microalgae FAME

Low-speed diesel engines are finding an increasing market for marine

applications and large scale electric power generation due to their high combustion

efficiency. Unfortunately, diesel engine exhaust emissions are increasing with

economic growth and causing widespread concern in terms of environmental pollution

[3, 96, 112-114]. However, diesel engine performance with FAME microalgae has

been investigated by only a small number of researchers [3, 86, 87]. Their results differ

due to the difference in engine operating conditions and the variation in fuel properties

[3, 86]. High viscosity and low volatilities of microalgae FAME is one of the main

reasons for diesel engine tests over long-periods. Higher viscosities of microalgae

biofuel affects fuel droplet size, resulting in poor atomisation and fuel penetration in

the cylinder, which is very important for combustion, but it reduces emissions relating

to the oxygen content in the biofuels [5, 29, 115]. The influence of microalgae

biodiesel (FAME) on exhaust emission (only gases) is shown in Table 3.5.

Hydrocarbon (HC) and CO are consistently lower compared to diesel when using

microalgae biodiesel as shown in Table 3.5. Conversely, nitrogen oxide emissions

showed no consistent trend.


Table 3.5: Influence of microalgae biodiesel (FAME) on exhaust emissions [116].

University FAME blend HC CO NOx References

Queensland University of

Technology, Australia

10%MBD+90%D

20%MBD+80%D

50%MBD+50%D

↓ ↑ [3]

Aleksandras Stulginskis

University, Lithuania 30%MBD+70%D ↓ ↓ ↑ [117]

Çukurova University,

Turkey

5%MBD+95%D

10%MBD+90%D

25%MBD+75%D

50%MBD+50%D

↓ ↓ [87]

Colorado State University,

USA

20%MBD+80%D ↓ ↓ ↑ [118]

Utah State University, USA 100MBD ↓ ↓ ↓ [34]

Legend: ↑- increase, ↓- decrease, ↓↑- near equal. MBD= Microalgae, D+ Diesel

Tuccar et al. [86] conducted emission and engine performance tests using a four-

cylinder diesel engine with microalgae biofuel blends. The average torque value of the

engine reduced approximately 2.7% for D80B20 blend compared to that of diesel fuel.

The oxygen content of microalgae biofuel led to a decrease in the brake torque and

brake power when compared to diesel fuel [86]. The highest BSFC values increased

by 10.9% for D80B20 compared to diesel fuel. Conversely, the CO, particulate matter

(PM), and HC emissions were lower for microalgae biofuel blends [86, 87]. Islam et

al. [3] investigated microalgae biofuel exhaust emission and engine performance in a

common rail four-cylinder diesel engine. The BTE decreased for different microalgae

biodiesel (FAME) blends compared to diesel fuel and BSFC increased but exhaust

emissions improved [3]. However, due to the high flash point, density and lubricity,

the combustion efficiency reduced but emissions improved because of the oxygen

content in the microalgae biofuel.

3.3.2 HTL Microalgae biocrude

An extensive literature review by the authors did not find any literature relating

to diesel engine performance and exhaust emission measurements using microalgae

HTL biocrude. Due to the physicochemical properties of the HTL biocrude it is not


biocrude 49

possible to use it in a conventional high-speed diesel engine without first upgrading.

However, the HTL biocrude could be used in heavy duty marine diesel ship engines

(low-speed diesel engine). Marine ship engines generally use HFO, which has several

common properties to HTL biocrude [54, 71, 119, 120]. HFO produces high levels of

emissions due to physicochemical properties of the HFO in particular high kinematic

viscosity and sulphur (shown in Table 3.6). It is also noted that while researchers

generally have better access to on-road vehicle emission information, it is not easy to

access ship engines for testing performance of biofuels and their emissions [97].

Almost 80% of marine engines worldwide are dominated by just a few companies such

as MAN, BMW, Wartsila and Mitsubishi. These companies have very few engine

dynamometers and scientists are rarely granted access to such extraordinary facilities

[97, 121]. So, it is quite difficult to explore the exact emissions from marine diesel

engines. However, HTL microalgae biocrude seems to be a suitable substitute to HFO

based on their properties (as shown in Table 3.6). There are vast applications of HFO,

such as marine diesel engines, steam boilers, and power plants. Exhaust emissions are

much higher compared to diesel fuel due to their chemical composition [97]. On the

other hand, HTL biocrude could be a viable alternative to HFO. It would be a great

achievement in terms of emission reduction because HTL biocrude comes from

renewable sources. Microalgae HTL biocrude could be a good alternative fuel for

marine diesel engines, which would reduce exhaust emission substantially.

HFO can’t be used in high-speed diesel engines due to its fuel properties. The

properties of diesel/biodiesel and HFO are fundamentally different, including density,

viscosity, and HHV. However, Rahman et al. [27] and Pham et al. [30] experimentally

investigated the effect of the physicochemical properties of biodiesel on high-speed

diesel engine exhaust emissions. Exhaust emissions from diesel engine vehicles and

power plants contain a high concentration of nano-sized particles and gaseous

pollutants [19, 31, 32]. Fine particles are present in heavy-duty diesel engine exhausts,

which can cause cancer and other diseases due to their small size [27]. Alternative

fuels, such as those from microalgae, are another one of the potential options for

reducing emissions [33-37]. Also, using biodiesel in diesel engines has the potential to

greatly reduce carbon emissions and is a renewable source of energy. Many groups

have investigated novel uses of conventional biofuels in diesel engines to investigate

engine performance and exhaust emissions [3, 29, 38]. Alternative drop-in fuels for


transportation provide an excellent opportunity for reducing greenhouse gas (GHG)

emissions as they can be incorporated into existing fuel-distribution networks with

minimal engine modification. This will support energy security and environmental

sustainability. Second- and third-generation biofuel must be actively developed

because they come from biomass, which do not affect the food chain. Microalgae

biomass presents the advantages of rapid growth, high oil yield per unit area, and being

cultivated on land unsuitable for other forms of cultivation [39].

Table 3.6: Qualitative comparison between microalgae HTL biocrude and HFO.

Fuel Properties Diesel

Microalgae

HTL

biocrude

HFO

Similarity between

HTL & HFO

Density Low High High Similar

HHV High Medium Medium Similar

Appearance Yellow Black Black Similar

Viscosity Low Medium High Moderately similar

Hydrogen content High Low Low Similar

Carbon content High Low Medium Moderately similar

Nitrogen content No High Medium Not similar

Sulphur content Low No High Not similar

Ash content Low Low High Not similar

Asphaltene content Low Low High Not similar

Heavy duty marine diesel engine exhaust emissions contribute significantly to

the total exhaust emissions from the transport sector globally. In addition, shipping

offers a lower GHG option for the transport of goods [122]. Almost two-thirds of all

heavy marine engines are operated with HFO [119]. The heavy-duty marine diesel

engine uses HFO as a primary fuel, which usually contains high amounts of sulphur

compounds. The relatively high amount of sulphur in HFO is approximately ten times

higher than that of light fuel oil (LFO), which generally produces sulphuric acid with

other exhaust emissions [112]. It is crucial nowadays for shipping companies to reduce

bunker consumption while maintaining a certain level of shipping service in view of

the high bunker price and concern about shipping emissions [123, 124]. The emissions

are different due to the fact that the vessel types and measurement methods are

different. However, most of the vessels use HFO/marine fuel oil (MFO)/residue; none

use renewable HTL biocrudes. Therefore, this HTL biocrude could be an alternative

for marine engines.


biocrude 51

Table 3.7 shows emissions for various types of ocean-going vessels. The

emissions are different due to the fact that the vessel types and measurement methods

are different. However, most of the vessels use HFO/marine fuel oil (MFO)/residue;

none use renewable HTL biocrudes. Therefore, this HTL biocrude could be an

alternative for marine engines.

Table 3.7: Exhaust emissions for different ocean-going vessel using

HFO/MFO/residual.

Vessel

type

Measurement

type

g NOx/kg

fuel

g SO2/kg

fuel

Type of fuels Reference

HFO/MFO HTL

Various Remote 72 ± 24 30 ±15 HFO

Res

earc

h g

aps

[125]

Container Onboard 85.9 ± 0.5 50.3b HFO [126]

Freight Remote 87.0 ± 29.6 20.4 ±5.6 HFO [127]

Container Remote/

Onboard

59.8 ± 20.8 30.4 ±16.6 HFO [127]

Crude

tankers

79.2 ± 23.4 27.3 ±17.4 HFO [128]

Container Onboard 90.5a 41.6b HFO [129]

Ship Remote

(airplane)

43 ± 26 23 ± 7 MFO [130]

Container Remote

(airplane)

65.5 ± 3.3 52.2 ± 3.7 Residual [131]

However, environmental legislation regarding exhaust emissions and a high

dependency on fossil fuels set the scene for a growing area of research concerning

alternative fuels and their effect on engine performance and emissions [43]. Similar to

HFO, the HTL biocrude is also receiving much attention in recent years due to high

yields and its ability to utilise wet biomass [47]. With the HTL method, biomass is

changed into gas, liquid and solids such as common pyrolysis in the gas phase [48].

The HTL biocrude could be an alternative of HFO, which is used for marine engine

operation. It will help to reduce exhaust emissions for heavy duty diesel marine

engines and will improve engine performance for HTL biocrude.


3.4 CONCLUSION

Microalgae-based biofuels have potential for replacing fossil fuels in both high-

speed and low-speed diesel engines. Microalgae HTL biocrude could be used in low-

speed diesel engines including marine diesel engines and large power generators

without further treatment due to their properties, which are similar to HFO. This could

mean that microalgae HTL biocrude could be a future fuel of marine diesel engines.

However, the chemical composition including sulphur, nitrogen and oxygen content

of HTL are different, which both affect engine performance and exhaust emissions.

HTL biocrude would reduce exhaust emissions for low-speed marine diesel engines

compared to HFO, especially soot emissions due to their very low sulphur content,

although NOx emissions may increase. Furthermore, HTL may reduce the engine

performance in terms of output power compared to HFO due to their higher oxygen

content and lower HHV. Conversely, solvent-extraction and transesterification to

produce microalgae FAME is better suited to high-speed diesel engines, such as heavy

vehicles, as a substitute for diesel. The physicochemical properties of FAME

microalgae and diesel are similar except for the higher oxygen content in FAME.

Therefore, microalgae FAME results in high-speed diesel engines having decreased

emissions but there is a small penalty in terms of engine power compared to diesel

fuel. Both, microalgae FAME and HTL, types of fuel could be used to reduce exhaust

emissions and also replace fossil fuel in the future although further improvements

could be made with more research.

3.5 ACKNOWLEDGEMENTS

This research was supported by the Australian Research Council’s Linkage

Projects funding scheme (project number LP110200158). The author would like to

acknowledge Dr. Mohammad Aminul Islam for assistance with reviewing this

manuscript.

Chapter 4: Literature review on thermochemical conversion of waste tyres 53

Chapter 4: Literature review on

thermochemical conversion

of waste tyres

Abstract:

The growing demand of transport and the development of industrialised

countries increases the production of tyres every year. ELTs are a significant

environmental hazard; the mass that is generated each year is around 17 million tons.

It has been found that a thermochemical conversion process can convert whole tyres

into oil, which has similar characteristics to diesel and gasoline. The Australian Bureau

of Resource and Energy Economics has reported that petroleum consumption in

Australia has reached about 64 billion litres per annum with nearly 70% used for

the transport sector in 2013. Diesel fuel holds the largest share, which is 41%. It is

estimated that around 1% of diesel fuel could be replaced by waste-tyre oil in

Australia. This review summarises two recent conversions of waste tyre to oil and the

application of that fuel in diesel engines. The first step was to develop a process to

convert waste tyres to tyre oil, which could be used in a diesel engine directly or as a

blended fuel. The second step was to analyse and measure its performance and

emissions in diesel engines to determine the viability of using oil from waste tyres as

fuel, since it has less impact on the environment and retains the same performance in

the vehicles. In addition, the thermochemical conversion of waste tyres produces steel

and carbon/char, which could be used in the re-rolling and cement manufacturing

industries respectively.


4.1 INTRODUCTION

The rapid global spread of industrialisation has led to an increase in the

production of vehicles as a primary means of transport to mobilise citizens and grow

economies. Very large numbers of waste tyres are generated every year [12, 13, 132,

133]. The number of tyres produced worldwide is approximately 1.5 billion per year,

which means the same number are ending up as wasted tyres. This is the equivalent of

about 17 million tons [26, 134, 135]. Most of the waste tyres are stored for disposal,

which represents an environmental problem because the life of a tyre is so long.

Recycling waste tyres is extremely difficult because of their highly complex structure,

the diverse composition of the raw material, and the chemical structure of the rubber

from which the tyres are manufactured. The process of manufacturing rubber products

is based primarily on the irreversible vulcanisation reaction that takes place between

natural and synthetic diene rubbers, sulphur and a variety of auxiliary compounds.

Therefore, transverse bonds connect the elastomer chains to and from the cross-linked

structure of the rubber. As a result, rubber is characterised by elasticity, insolubility

and infusibility, which do not permit being easily reprocessed. Their recycling requires

much time and energy and is based mostly on mechanical, thermochemical destruction

[136]. A tyre consists not only of rubber, which makes up some 70–80% of the tyres

mass, but also of steel belts and textile overlays, which give the tyre its ultimate form

and utilitarian properties, which are shown in Table 4.1.

For the last decade, the management of waste tyres has been regulated by

organisations such as the Waste Management Association of Australia (WMAA),

which controls the final destination of waste tyres [137]. There are many ways to

recycle used tyres. The most common uses for waste tyre recycling are: waste tyre to

oil, rethreading, energy recovery, product recycling and material recycling.

The most common method used to process ELTs into fuel is pyrolysis, which is

a form of thermochemical conversion. Pyrolysis is the thermal degradation of the

organic component of tyres at a high temperature to produce oil, gas and char and

recovery steel [13]. The oil obtained from this process can be used directly in

industrial application and in diesel engines or further up graded. The most important

characteristic of this oil is the low exhaust emission in comparison with petroleum-

derived fuel oils. There is a large amount of research covering diesel engine

performance and emissions using tyre pyrolysis oil [24, 26, 138, 139].


Table 4.1: Major components of tyres [135, 137, 140, 141].

Components of

tyre

Average

composition

of tyre

Composition of tyre

in USA

Composition of tyre

in European Union

Passenger Truck Passenger Truck

Total rubber 45–47 -- -- -- --

Natural rubber -- 14 27 22 30

Synthetic rubber -- 27 14 23 15

Carbon black 21.5–22 28 28 28 20

Steel 16.5–25 14–15 14–15 13 25

Textile 5.5 16–17 16–17 14 10

Average

weight

New -- 11 54 8.5 65

Old -- 9 45 7 56

4.2 WASTE TYRE TO OIL USING THERMOCHEMICAL CONVERSION

Thermochemical conversion methods conducted at high temperatures, with or

without the presence of oxygen, chemically degrade waste tyres. Pyrolysis, thermal

cracking and gasification conversion methods are used to produce fuel [68, 69, 142,

143]. Among different possible solutions, one potential resolution to the issue of tyre-

waste settlement is to transform them to fuels along with other related hydrocarbon

(HC)-based products using thermochemical processes [144].

4.2.1 Waste conversion using pyrolysis

The pyrolysis process, among other similar thermochemical processes, is

assumed to be most friendly to the environment due to the fewer processing steps

involved [144]. The process involves the decomposition of the solid at a considerably

inflated temperature of around 300 °C to 900 °C in an environment that is free of

oxygen and resultantly producing char, oil and gas [68, 145-148]. The crucial

conditions in the experiments that have impact include the degree of temperature and

the rate of heating. Based on these factors, the resulting oil and energy yield is

determined and are assessed in the diesel engine for evaluation in respect to

performance and emissions. Research has also revealed that inflated temperatures

along with increased gas residence in the heated areas of the reactor can have a

negative influence on the fuel and the conversion of oil to gas. Varying yield outcomes

due to the pyrolysis process are dependent upon different conditions and reactor

settings [146, 149].


Many technologies have been developed for the generation of ethanol, char,

biodiesel etc. using the pyrolysis process. Temperature is the main factor to control the

configuration of the pyrolysis process. There are three main kinds of pyrolysis: (i) slow

pyrolysis process, (ii) fast pyrolysis process, and (iii) flash pyrolysis process. The

pyrolysis processes depend on factors such as temperature, material size, period etc.

[68, 150]

There is a different type of pyrolysis reactor used to produce waste tyre to oil,

char and gas. The pyrolysis process using various temperature ranges depend on

reactor types and product yield. The reactor is the same but product yield is different

due to the operating conditions. Table 4.2 shows a range of pyrolysis reactors and their

product yield for waste tyres.


Table 4.2 Collection of pyrolysis reactors and product yield from the pyrolysis

of waste tyres.

Reactor

Experimental

Condition

Maximum oil yield Refer-

ences

Temp

C

Oil

wt.%

Char

wt.%

Gas

wt.%

Fixed bed

batch

400–700C Temp. 500 40.26 47.88 11.86 [132]

Closed batch

reactor

350–450C Temp.

30 min-1 heating

rate

450 ~63 ~30 ~7 [151]

Fixed bed,

batch

350–600C Temp

5C min-1 and 35

min-1 heating rate.

400 38.8 34.0 27.2 [152]

Fixed bed,

batch, internal

fire tubes

375–575C Temp:

750g tyre

475 55 36 9 [153]

Moving screw

bed

600–800C Temp.

3,5–8.0kgh-1 mass

flow rate

600 48.4 39.9 11.7 [154]

Two stages

fixed bed

reactor

600–800C Temp

2 ml h-1 flow rate

600 5.03 39 81.1 [155]

Two stages

fixed bed

reactor

600–800C Temp

5 ml h-1 flow rate

600 10 38 82 [155]

Two stages

fixed bed

reactor

600–800C Temp

Not water

600 22

37 27.2 [155]

Quartz

microwave

oven reactor

Flow rate nitrogen

1L-0,4L m-1

450Watts

450–650C

- 43 45 12 [156]

Rotary reactor 600–1000C ratio

0.2. Using waste

heat of blast-

furnace slag.

600 30.21 62.67 7.12 [157]

Rotary reactor 600–1000C ratio

0.6. Using waste

heat of blast-

furnace slag.

1000 55.8 33.67 10.50 [157]


4.2.2 Thermal cracking of waste tyre

Thermal cracking is a recent thermal conversion for waste tyres. The pyrolysis

process transfers the colloidal particles to the pyrolysis furnace for pyrolysis, and the

colloidal particles are then subjected to thermal cracking at high temperature and high

pressure. Colloidal particles refer to substances of a minor size that are floating in a

medium of one of three substances: a solid, a liquid, or a gas. Colloidal particles are

heterogeneous in medium. The gas-phase product enters the washing tower to

condense and cool, and the condensed fuel oil is stored in the cooling tank. Non-

condensable HC gas phase is recovered as a gas, from the pyrolysis furnace [158].

Figure 4.1 shows the thermal cracking process for waste tyre to fuels.

Waste tyre

1. whole

2. Commuted

Thermal Cracking

1. Temperature (350 C – 1000 C)

2. Absence of oxygen

3. Fixed bed batch

4.Close batch

5.Rotary reactor

CondenserChar

(40 – 50) wt. %

Steel wire

(15-20) wt. %

Tyre Oil

(40 – 60) wt.%

Figure 4.1: Thermal cracking of waste tyre [158].

4.3 WASTE TYRE TO OIL, CARBON AND STEEL

Recycling of waste tyres into useful products is of interest for both

environmental and economic reasons. Many researchers have been working to solve

the above issues and convert waste tyres into valuable products including oil, carbon

and steel. Waste-tyre oil could be used by industry for heating purposes, further refined

for use in diesel engines or used directly as blended fuel in some stationary diesel

engines. Carbon has a plethora of industrial uses, from toothpaste to electrodes and

pharmaceutical goods, as well as being about 35% cleaner than coal and burning

hotter, while steel can be sold as scrap metal or returned to tyre manufacturers for

reuse.


4.3.1 Oil from waste tyres

Oil from waste tyres using a thermochemical conversion process is varied due

to the conversion process and the operating conditions. The tyre oil colour is black and

it also has a recognisable odour. Table 4.3 shows the physicochemical properties of

fuel. Those properties identify the fuel category and quality. In Table 4.3, two different

types of tyre oil are presented: one that is produced using pyrolysis and the other that

is produced by a destructive distillation process invented by GDT. Pyrolysis oil density

is higher than that of biodiesel, diesel and GDT-tyre oil. However, GDT-tyre oil

properties are similar to diesel, therefore making it suitable to be used in a diesel engine

directly. Tyre pyrolysis oil is not suitable.

Table 4.3: Physicochemical properties of tyre oil, WCBD and diesel.

Properties Units Diesel Biodiesel

(WCBD)

TPO DGT_

TO

References

Density Kg/L 0.83 0.88 0.91–.96 0.84 [3, 12, 24]

HHV MJ/L 45.6 37.2 38–42 42.3 [3, 12, 24]

Water content mg/kg <30 -- 118 [12, 24]

Aromatic % m/m 26.0 -- 39.3 21.4 [12, 24, 159]

Kinematic V. mm2/s 2.66 4.73 3.22–6.3 3.43 [3, 12, 24]

Carbon © Wt. % 87.0 76.9 79.61–88 [3, 12, 24, 133]

Hydrogen (H) Wt. % 13.0 12.2 9.4–11.73 [3, 12, 24, 133]

Nitrogen (N) Wt. % -- -- 0.40–1.05 [3, 12, 24, 133]

Oxygen (O) Wt. % 0 10.9 0.5–4.62 [3, 12, 24, 160]

Ash content Wt. % 0.01 .002–0.31 10* [12, 160]

Flash point ° C 50 130 20–65 97 [12, 160]

Cetane index 53.2 58.6 28.6 51.7 [3, 24]

*ppm

4.3.2 Char from waste tyres

The chars from waste-tyre pyrolysis are another valuable product. It is reported

that the char produced from tyre conversion ranges from 22–49% by weight [12].

There are many researchers that have been investigating the characteristics of the char.

Table 4.4 shows the properties of waste tyre char. The chars have a low heating value,


29.3–31.5 MJ/kg, compared to tyre oil, which has a range of 38–42 MJ/Kg. The tyre

char can be used by different industries including cement and fertiliser.

Table 4.4: Properties of waste-tyre chars.

Properties Units Tyre pyrolysis char

[161] [162] [163] [164]

HHV MJ/kg 30.8 31.5 30.7 29.3

Water content mg/kg 0.37 2.35 3.57

Carbon (C) Wt. % 88.19 82.17 85.31 80.3

Hydrogen (H) Wt. % 0.6 2.28 1.77 1.3

Nitrogen (N) Wt. % 0.1 0.61 0.34 0.3

Sulphur (S) Wt. % 1.9 2.32 2.13 2.7

Ash content Wt. % 8.27 12.32 15.33

4.3.3 Steel from waste tyre

Waste tyres also produce steel when converted by a thermochemical process. It

is reported that the amount of steel recovered from waste tyres typically ranges from

10–15% by weight of the waste tyre [12]. The recovered steel can be reused by the

tyre manufacturer or diverted to steel re-rolling mills.

4.4 DIESEL ENGINE PERFORMANCE AND EXHAUST EMISSION

USING TYRE OIL

According to various researchers [136, 159], the resulting properties from waste-

tyre pyrolysis have similar characteristics to that of diesel and gasoline. The diesel

engine is a widely used internal combustion engine in current times. An increase in the

demand for diesel fuel and associated limited resources have resulted in a search for

alternative fuels for running diesel engines, such as alcohol, LPG, biodiesel, and CNG

[145]. The studies in the literature show differing results due to different properties of

the test fuels and different test-engine technology [165]. There are many variables to

control in an analysis on emissions in engines, for example, engine speed, fuel

composition and load condition. The fuel derived from tyres has proved to be one of

the most important and useful research outputs. However, there has been limited

funding directed at the use of tyre-derived pyrolytic fuel or diesel-blend fuel because

effects on overall engine performance as well as emissions have not been sufficiently


confirmed. Hence, further research focusing on the emissions from diesel engines

using oil from waste tyres is expected to have a favourable impact in alternative

industries. Moreover, it could also be a promising possibility in the search to find low-

emission sources of energy.

In recent years, tests on diesel engine performance with tyre oil have been

performed by many researchers [24, 26, 138, 166]. Vihar et al. [24] experimentally

analysed the combustion characteristics of tyre pyrolysis oil in a turbo-charged six-

cylinder compression ignition engine. They found stable combustion without engine

modification as well as almost the same thermal efficiency as diesel fuel. Kapura et al.

[138] studied the effect of diethyl ether in a diesel engine run on a tyre-derived fuel-

diesel blend. They blended 40% tyre-pyrolysis oil with diesel and simultaneously 4%

diethyl ether was added to improve the CN of the blended fuel. It has been reported

that those blended fuels reduced the NO emission by approximately 25% with respect

to diesel operation at full load [138]. Cumali and Huseyin carried out an experimental

investigation of fuel production from waste tyres using a catalytic pyrolysis process

and tested it in a diesel engine. They tested several types of blended fuels in a diesel

engine including 100% tyre oil. It was reported that 50%, 75% and 100% tyre-oil

blends raise CO, HC and SO2 exhaust emissions when compared to diesel emissions.


4.5 CONCLUSION

The use of waste tyres as an alternative fuel to solve the global problem of waste

tyre management, and the importance of a thermochemical process, is the focus of this

research.

Even though tyre pyrolysis oil is still a relatively new product and possibly needs more

research regarding its properties and application, it is nevertheless an innovative

solution to the problem of waste tyres.

The diesel engine experimental results on engine performance and emissions

with different tyre-oil blends were carried out using diesel as a principal fuel. In most

cases it was found to reduce exhaust emissions without any penalty to engine

performance.

Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large

batch reactor 63

Chapter 5: Experimental measurements of

physical and chemical properties

of microalgae biocrude using a

large-batch reactor

Farhad M. Hossain1,2*, Jana Kosinkova1,2, Richard J. Brown1,2, Zoran

Ristovski1,2, Ben Hankamer3, Evan Stephens3 and Thomas J. Rainey1, 2,

1 Biofuel Engine Research Facility, Queensland University of Technology (QUT), Brisbane,

Queensland 4001, Australia 2 QUT, International Laboratory for Air Quality and Health 3 University of Queensland, The Institute for Molecular Bioscience, 306 Carmody Road, St Lucia,

QLD 4072, Australia



1. they meet the criteria for authorship in that they have participated in the conception, execution, or


2. they take public responsibility for their part of the publication, except for the responsible author who


3. there are no other authors of the publication according to these criteria;

4. potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or publisher of


5. they agree to the use of the publication in the student’s thesis and its publication on the Australasian


Title and status: Experimental investigation of physical and chemical properties of

microalgae biocrude using a large-batch reactor, (Published at Energies)



Conducted the experimental work, performed data analysis, interpreted

the results wrote the manuscript and acted as the corresponding author.

Signature

Date

Jana Kosinkova Dr Jana Kosinkova graduated in Chemical Engineering from Slovak

University of Technology. Her research interests focus on the


optimisation of thermal liquefaction processing for second- and third-

generation feedstocks for the production of biocrude oils.

Conducted the experimental work in a group, performed data analysis

and helped to write the manuscript.


Professor Richard Brown is a mechanical engineer, he is a leading expert

in thermodynamics and environmental fluid mechanics, particularly in

relation to internal combustion engine performance and emissions.

Professor Richard Brown designed and performed fuel properties related

to engine performance and reviewed the manuscript as a principal

superviser.

Zoran Ristovski Associate Supervisor

Professor Zoran Ristovski is a physicist who works at Queensland



Professor Zoran Ristovski designed and performed fuel properties related

to engine exhaust emissions and reviewed the manuscript.

Ben Hankamer Professor Ben Hankamer is Group Leader, Chemistry and Structural

Biology Division Director, Breakthrough Science Program in Algal

Biomedicine Co-Director, Breakthrough Science program in bio-

membrane design.

Professor Ben Hankamer provided the raw microalgae for biofuel

production as a collaboration work and reviewed the manuscript.

Evan Stephens Professor Evan Stephens and the team at UQ’s Institute for Molecular

Bioscience, in collaboration with Germany’s Bielefeld University and

Karlsruhe Institute of Technology, have identified fast-growing and

hardy microscopic algae that could prove the key to cheaper and more

efficient alternative fuel production.

Professor Dr Evan Stephens provided the raw microalgae for biofuel

production as a collaboration work and reviewed the manuscript.

Thomas J. Rainey Associate Supervisor

Dr Thomas Rainey has 15 years of industrial and research experience in




batch reactor 65

Design concept, reviewed and edited the manuscript in the section related

to biofuel production and properties analysis.


I have sighted email or other correspondence from all Co-authors confirming their certifying authorship.


Name Signature Date


Abstract:

As a biofuel feedstock, microalgae have good scalability and potential to supply

a significant proportion of world energy compared to most types of biofuel feedstock.

Hydrothermal liquefaction (HTL) is well suited to wet biomass (such as microalgae)

as it greatly reduces the energy requirements associated with dewatering and drying.

This article presents experimental analyses of chemical and physical properties of

biocrude oil produced via HTL using a high-growth-rate microalga, Scenedesmus sp.,

in a large-batch reactor. The overarching goal was to investigate the suitability of

microalgae HTL biocrude produced in a large-batch reactor for direct application in

marine diesel engines. To this end we characterised the chemical and physical

properties of the biocrudes produced. The HTL literature mostly reports work using

very small-batch reactors, which are preferred by researchers, so there are few

experimental and parametric measurements for biocrude physical properties such as

viscosity and density. In the course of this study, a difference between traditional

calculated values and measured values was noted. In the parametric study, the biocrude

viscosity was significantly closer to regular diesel and biodiesel standards than

transesterified (FAME) microalgae biodiesel. Under optimised conditions, HTL

biocrude’s high density (0.97–1.04 kgL-1) and its high viscosity (70.7–73.8 mm2s-)

had enough similarity to marine heavy fuels, though the measured higher-heating value

(HHV) was lower (29.8 MJ kg-1). The reaction temperature was explored in the range

280–350 °C and biocrude oil yield and HHV reached their maxima at the highest

temperature. Slurry concentration was explored between 15–30% at this temperature

and the best HHV, O:C and N:C was found to occur at 25%. Two solvents

(dichloromethane (DCM) and n-hexane) were used to recover biocrude oil, affecting

the yield and chemical composition of the biocrude.

KEYWORDS: Microalgae, HTL, biocrude, FAME, fuel properties.


batch reactor 67

5.1 INTRODUCTION

Microalgae are of considerable interest for the production of next-generation

biofuels [10, 32] that are indistinguishable from petroleum fuels based on their

properties [2]. This is because using microalgae for biofuel production would have

fewer adverse effects on food supply and other agriculture [167, 168] as they can be

cultivated on non-arable land using fresh, waste or saline water sources, enable more

efficient nutrient recycling and achieve higher productivities [169, 170].

A range of conversion techniques are under development to generate biofuels

from microalgae. These include solvent extraction followed by trans-esterification to

produce fatty acid methyl esters (FAME), fermentation to alcohols, as well as

thermochemical conversion pathways such as pyrolysis and hydrothermal liquefaction

(HTL) [171, 172] to produce biocrude oils. HTL efficiently converts wet microalgae

biomass feedstock into biocrude oil [51, 54, 173] as it eliminates the need for

expensive pre-drying of the raw material. Compared to trans-esterifying lipids

obtained from microalgae by solvent extraction, HTL has the potential to require less

energy for the conversion process, which would improve production costs [71]. The

high-solvent losses associated with FAME production means its financial viability is

directly related to the lipid content (high lipid content being better) whereas HTL can

make use of more highly-productive microalgae species (i.e. more tonnes per hectare),

which have higher carbohydrate content, lower lipid content and the potential for

additional co-products [174]. These advantages of HTL make it a competitive route

for the conversion of raw microalgae biomass to fuels [51, 54, 173].

HTL converts microalgae biomass into biocrude oil as well as aqueous, gas and

solid phase products at elevated pressures (5–24 MPa) and moderate temperatures

(250–400 °C) [68, 69]. A wide range of microalgae biomass feedstocks has been

explored using HTL, including laboratory and commercially grown strains

Botryococcus braunii [55], Arthrospira (Spirulina), Scenedesmus sp [175]. and

Tetraselmis sp. [32]. Among the green microalgae the most common Scenedesmus sp.

has high productivity although the lipid yield can be optimised to reach over 60%

[176], which makes this strain attractive for biofuel production. In general, the

variation in the biochemical composition, particularly the carbon-chain length and the


degree of saturation, affects the conversion rate and the chemical-physical properties

of the HTL biocrude [57, 177].

The effect of operating conditions such as residence time, temperature, slurry

concentration and catalyst, on physical and chemical properties of microalgae HTL

biocrude have been investigated previously in limited studies [47, 49, 178, 179]. In

this study, three temperatures and slurry concentrations were investigated in the range

280–350 °C and 15–30% respectively; temperature and concentration, as well as

reaction time of 60 min was based loosely on literature [49, 51]. Higher temperatures

were not explored so as to remain below water’s supercritical point. Jena et al. [49]

demonstrated that among the various process parameters the temperature had the

strongest influence on the higher-heating value (HHV), viscosity and chemical

composition. HTL produces biocrude oil that by weight can have 6 to 8 times higher

oxygen and nitrogen content than heavy fuel oil (HFO) [97]. The inorganic salts in

many types of HTL biocrude oil require modifications to be compatible with a

traditional refining process [32, 51, 72, 180]. Biocrude oil may also need subsequent

upgrading to improve quality and reduce these undesired components.

Most experimental research in HTL continues to use small-batch reactors (less

than 1000 ml), while scale-up reactors are usually continuous. The kinetics of small

size reactors or autoclaves may differ from large ones, both batch and continuous,

which lead to different chemical reactions. Therefore, the results from these reactors

are not fully reliable in terms of scale-up. Batch reactors are commonly used to validate

the process conditions for further commercial scale. Although industry tends to prefer

continuous reactors to batch reactors because of higher energy efficiency, the steady

production rate and uniformity of product, large-batch reactors still have several key

advantages:

Pumping the biomass slurry into continuous reactor at high pressure and

temperature remains technological challenge at industrial scale

Ability to switch easily between feedstocks.

For a factory, individual reactors can be taken out-of-service for maintenance.

Due to the lack of biocrude for testing, most groups only reported values at

optimised parameters. The aim of this study was to conduct more comprehensive


batch reactor 69

experimental analyses with three key objectives; (i) to empirically investigate the

relationship between the reaction parameters and experimentally determined values

for biocrude oil’s physical properties of biocrude, (ii) to evaluate how the chemical

composition varies with operating conditions, and (iii) to identify the best possible fuel

physical and chemical properties of microalgae HTL biocrude. Both physical and

chemical properties are needed to meet legislated diesel and FAME biodiesel

standards. In further analysis, the physical properties of the optimal biocrude were

compared with other fuel standards to determine the similarities and reveal areas for

improvement.

5.2 MATERIALS AND METHODS

5.2.1 Hydrothermal Liquefaction (HTL)

The experiments were performed in a 1.8 L batch reactor system (Parr

Instruments Co.) and data were collected across three physical variables: temperature,

slurry concentration, and solvents for recovering the biocrude from the liquid mixture.

The experimental temperatures used were 280 °C, 300 °C and 350 °C, and solid

concentrations in the slurry were 15%, 25% and 30% by weight. When loading the

reactor, the headspace was purged thoroughly using nitrogen to remove oxygen, and

pre-pressurised to 2 bar with nitrogen gas. The reactor was heated to the desired

temperature (heating rate ~3.3 °C/min) and held constant for one hour, which is

consistent with the literature [49, 181-185]. At the end of the reaction time, the reactor

was cooled by passing water through an internal cooling tube until room temperature

was reached. Experiments were performed in duplicate and the average yield of two

runs is reported. After the gas was vented from the reactor, the vessel was opened and

the mixture was separated (following the steps in Figure 5.1). The walls of the reactor

were washed thoroughly with solvent (dichloromethane (DCM) or n-hexane) and

mixed with the liquid phase. The amount of solvent added was determined as the

volume of the solvent per mass dry weight of algae. The solid phase was removed from

the liquid mixture by vacuum filtration before being washed with the remaining

solvent. The solids were then oven-dried at 105 °C overnight.

The liquid phase mixture was poured into a separation funnel and the water-

insoluble components (organic phase) were separated from the water soluble (aqueous)

phase. The solvent was evaporated from the biocrude by a rotary vacuum evaporator.


Due to the volatile nature of DCM we have used 40°C 760 Tor and placed an additional

trap between the vacuum source and the condenser unit. Whereas for n-hexane the

temperature was set up at 68 °C (760 Tor). The evaporation was continued until no

further yield was obtained. The time for the DMC was shorter than that for n-hexane.

Liquefaction of biomass slurry

Products mixture

Gas fractionWashing with

solvent

Liquid and solid

fraction

Vacuum filtration

Solid

residues

Liquid

fraction

Addition of solvent/phase separation

Organic phase Aqueous phase

Solvent removal

Solvent fractionWater soluble

fraction

Solvent removal/

Vacuum evaporation

Bio-crude oil

Figure 5.1: HTL product recovery workflow.

5.2.2 Raw materials

A robust and fast-growing green freshwater microalga, Scenedesmus sp., which

had been isolated as part of previous work [186], was used for these experiments. The

Scenedesmus sp. bulk biomass was produced at the University of Queensland’s Solar

Biofuels Research Centre facility at Pinjarra Hills near Brisbane, Australia. High

density slurry was frozen and stored at -20 °C directly after harvest to prevent

degradation during the HTL experiments. Proximate analyses were performed


batch reactor 71

according to American Society for Testing and Materials (ASTM) standards and using

a thermo-gravimetric analyser (TGA–NETZSCH thermal analyser). Ultimate analyses

were carried out using a LECO TruSpec Micro CHNS elemental analyser (Table 5.1).

The HHV of the dried microalgae sample was calculated according to the formula used

by Demirbas [187] and Friedl [188], which were 18.07 MJ kg-1 and 19.5 MJ kg-1

respectively for Scenedesmus species microalgae. The lipid content for the samples

used in this study was typically 15–20%.

Table 5.1: Microalgae proximate and ultimate analyses data.

Proximate analyses Ultimate analyses

Composition Percentage of weight

Element Percentage of weight

Fixed carbon 24.8 C 46.3

Volatile matter 67.3 H 6.9

Ash 3.2 O 32.3

Moisture 85 N 7.3

S 2.3

5.2.3 Analytical methods

The conversion and product yields were defined as the mass fraction of the

respective product (i.e. biocrude and solid residue) as a function of the initial mass of

biomass. For approximation, the total yield of gas + aqueous products were determined

by difference according to the approach commonly used in the literature [e.g. 189].

Solid residues (wt. %) = (mass of solid residues

mass of raw material ) x 100 ………………… (5.1)

Biocrude yield (wt. %) = (mass of bio−crude

mass of raw material ) x 100 ………………… (5.2)

5.2.4 Biocrude properties measurements

The chemical and physical biocrude properties such as higher-heating value

(HHV), viscosity, density and chemical composition were measured experimentally.

HHV of the biocrude was measured with a Parr 6200 compensated jacket calorimeter.

For comparative purposes, the correlations used for fossil fuels (liquid, gas and coal),

and that form the basis of calculation applied in other research articles, are Boie’s and

Dulong’s formulae, which are shown equations 5.3 and 5.4 respectively [187, 190].


HHV (MJ/kg) = 35.16 C + 116.225 H – 10.09 O + 6.28 N + 10.465 S----- (5.3)

HHV (MJ/kg) = 0.3383C + 1.422 (H – O/8) ----------------------------------- (5.4)

A Brookfield DV-III ultra-programmable rheometer was used to measure the

viscosity of the biocrude at constant temperature. The accuracy of the rheometer for

viscosity measurements is ±1.0% of full scale range for a specific spindle running at a

specific speed. The density of the biocrude was measured using German industrial

standard (DIN) 1306.

Gas Chromatography with Mass Spectroscopy (GC-MS) was used to identify

the chemical compositions in the biocrude samples. GC-MS analyses were performed

using a Thermoscientific, Trace 1310 system, equipped with a single quadrupole mass

selective detector (ISQ). Each sample was dissolved and diluted in DCM. The injector

was set to 250 °C and a Thermo TG-5MS (30 m long, 0.25 mm ID, 0.25 mm

film) column was used. The oven was programmed at an initial temperature at 50 °C

(held 1/min) then heated at a constant rate of 10 °C min-1 until a temperature of 250

°C was reached, and then held for 9 min with a split ratio of 1:25 and a column flow

of 1.4 mL min-1. The MS detector scanned from 40–400 m/z with a solvent cut time

of 1.8 min and the ion source and transfer line temps were both set at 250 °C. The

carrier mode was set to constant flow.

5.3 RESULTS AND DISCUSSION

To investigate the influence of reaction conditions on product yields, HTL was

conducted using a range of reaction temperatures, solid concentrations, and two types

of solvents (DCM and n-hexane) to recover the biocrude.

5.3.1 Influence of solvents in product separation

After completion of HTL, the biocrude must be separated from the aqueous and

solid phases. The most common solvents reported in the literature, with a focus on

maximising biocrude yield, are the organic solvents DCM, chloroform, acetone and

n-hexane [178, 185, 191]. However, there was insufficient information about the

effect of these polar and non-polar solvents on the biocrude quality. The data presented

in Figure 5.2 was obtained from experimental runs with 25% slurry concentration at

350 °C for 60 min in a nitrogen atmosphere.


batch reactor 73

Figure 5.2: Effect of solvent on the recovery of biocrude, solids and gas + aqueous

components after HTL treatment (350 °C, 60 min, 25% slurry concentration).

Suitable nonpolar (n-hexane) and more polar (DCM) solvents were selected

based on previous studies and the product yields and chemical composition were

compared (see section 3.4). For the same algae species, and under identical reaction

conditions, biocrude yield varied from 31.2% (wt.) with n-hexane to 33.6% (wt.) with

DCM. This differed from the results of Valdez et al. (2011) who obtained the highest

biocrude yield (39%) with nonpolar solvents (hexadecane and decane) and the lowest

value with 30 % DCM for Nannochloropsis sp. at 350 °C for 60 min [185]. This

supports the view that both biomass properties and the solvent type used for separating

products after HTL has an influence on biocrude recovery. However, as n-hexane has

a higher boiling point than DCM, this could lead to higher losses of volatile

compounds during the evaporation process and this could possibly account for the

small difference (2.4%). Despite this, DCM was used as a solvent of choice for product

separation in all subsequent experiments.

5.3.2 Effect of reaction temperature on yield and HHV The effect of three different temperatures (280, 300, 350 °C) was investigated

using a 60 min reaction time and a nitrogen atmosphere at an initial pressure of 2 bar

(Figure 5.3). Biocrude yield increased with temperature from 24.5% at 280 °C to

32.5% at 300 °C and reached a maximum of 33.6% at 350 °C, in the range analysed.

33.6 31.2

15.3 15.9

51.1 52.9

0

10

20

30

40

50

60

DCM n-Hex

Yie

ld (

%)

bio-crude

SR

gas+aqueous


Similar results for temperature’s influence on biocrude yield have been reported

recently [49, 178, 183, 192]. The HHV was characterised for biocrude generated at

temperatures of 300 °C and 350 °C only, due to an insufficient amount of biocrude at

280 °C. The HHV followed the trend of biocrude yield; it increased from 26.1 MJ.kg-

1 to 29.8 MJ.kg-1, which was approximately 50% higher than in the original microalgae

biomass. The solid residue yield decreased gradually from 20.1% to 15.3% with rising

temperature suggesting organic conversion mostly into the aqueous and gas phases.

These outcomes generally support processing at the higher temperature range where

biocrude yield was maximised. Higher temperatures than these were not investigated

because of potential corrosion issues related to supercritical fluids. To this end, 350 °C

was used for future experiments.

Figure 5.3: Influence of the reaction temperature on product yields at 25% solids

concentration and 60 min reaction time in a nitrogen atmosphere (2 bar at

commencement), values are for yield data.

5.3.3 Effect of solid concentration on yield and HHV Liquefaction of Scenedesmus sp. was conducted at 350 °C for 60 min in a

nitrogen atmosphere using a range of algae slurry concentrations between 15 to 30%

by weight (Figure 5.4). These results show that the solid concentration of algae slurry

may have had a minor had a modest effect upon the biocrude yield (ranging between

~28.9–33.6%) and HHV (26.5–29.8 MJ.kg-1) with the highest yields and HHV

observed at 25% biomass concentration. However, the slurry concentration did have a

25

27

29

31

33

35

0

10

20

30

40

50

60

70

280 300 350

HH

V (

MJ/

kg)

Yie

ld (

% w

t.)

Temperature (°C)

Bio-crude SR Gas + aqueous HHV


batch reactor 75

significant effect upon chemical speciation (see section 5.3.4). A similar trend for

biocrude and the water soluble fraction was reported by Jena et al. (2011). The fact

that biocrude yield peaked at the 25% slurry concentration suggests that the substrate

was limiting at lower concentrations and that H+ and OH- ions responsible for

liquefaction become limiting at higher concentrations [49]. The presence of active

hydrogen formed from the water under HTL conditions stabilises the biomass

liquefaction intermediates. This prevents formation of more new compounds that do

not decompose easily, producing a higher yield of biocrude [193]. The yield of the gas

+ aqueous fraction ranged between 51.1%–60.6% over the slurry solid concentration

range tested and the lowest yield 51.1% was observed at 25% solid concentration,

which corresponded with the highest biocrude yields. Solid residues increased from

10.5% to 17.1% with slurry concentration due to the increase of solid mass fraction in

the slurry. This corresponded with the report of Jena et al. [49] where solid residues

had a small increase (5.4%–7%) with solids concentration in range from 10%–50%

[49].

Figure 5.4: Effect of slurry concentration on the recovery of biocrude, solids and gas

+ aqueous components after HTL treatment (350 °C, 60 min). Standard deviations

are based on 2 replicates; values provided are for yield data.

25

26

27

28

29

30

31

0

10

20

30

40

50

60

70

15 25 30

HH

V (

MJ/

kg)

Yie

ld (

% w

t.)

Slurry concentration (%)

Bio-crude SR Gas + aqueous HHV


5.3.4 Chemical characterisation of biocrude oil The chemical composition of each biocrude oil sample was characterised by GC-

MS. Due to the complex composition of the biocrude oil, only abundant compounds

were evaluated based on the peak areas (defined by the percentage of the

chromatographic area of the compound out if the total area). GC-MS revealed distinct

amounts of chemical compounds, which consisted of more than 2% of the total area

within the retention time range of 3–34 min. Around 64 compounds were identified

which accounted for approximately 80–90% of the total peak area from all bio-oil

samples and 28 of them are listed in Table 5.2 and Table 5.3. The majority of the

compounds obtained were cyclic nitrogenates (e.g. pyrolle, pyrazine, piperidine) and

cyclic and aromatic oxygenates (e.g. phenols, ketones), which is similar to previous

studies [49, 175, 182]. These compounds are formed from carbohydrates and proteins

obtained from the feedstock that undergo depolymerisations, decompositions and

reformation [194]. The minor compounds were mostly hydrocarbons (HCs) and esters,

which may be derived from lipid content. Lipids can produce stable HCs via

decarboxylation and decarbonylation reactions [194, 195]. The tables show a

comparison of the identified chemical compounds in the biocrude oil under different

reaction conditions.

Table 5.2 presents only the key compounds that were identified through GCMS

for both solvents. It shows the effectiveness of the n-hexane and DCM in terms of the

extraction of biocrude oil from the water-soluble fraction, independently. DCM and

n-hexane extracted 57.1% and 40.2% of heterocyclic and aromatic compounds

(mostly nitrogenated) from the water, respectively. Ketones were the most abundant

oxygenated compounds. Neither solvent had a strong influence on aliphatic recovery

rates, although a slight increase was observed with DCM. Valdez et al. (2011) also

reported that the total yields of aliphatic compounds did not vary significantly between

the polar to nonpolar solvents. They also found that DCM extracted more light low

molecular products such as aromatics, nitrogen-, oxygen- and sulphur obtaining

compounds, than n-hexane [185].


batch reactor 77

Table 5.2: Major compounds of recovered bio-oils obtained from HTL (350 °C, 60

min, 2 bar nitrogen atmosphere) using two different extraction solvents (DCM and n-

hexane).

RT

(min) Name of compound

Area %

DCM

n-

hexane

4.5 4-hydroxy-4-methyl , 2-pentanone 5.03 -

4.82 Ethylbenzene 8.86 3.38

4.98 1,4-dimethyl ,benzene 11.99 6.34

5.44 1,3-dimethyl ,benzene 3.44 5.12

5.82 2,5-dimethyl-,pyrazine 4.09 -

6.91 2,6-dimethyl-, 4-heptanone - 4.74

7.54 Trimethyl pyrazine 2.76 4.3

7.79 2,3,5-trimethyl-, 1H-pyrrole - 3.06

8.18 2,3-dimethyl-, 2-cyclopenten-1-one 5.32 4.36

8.49 3,7-dimethyl ,undecane - 2.82

8.77 4-methyl , phenol 3.53 4.45

9.06 1- acetate 1,2,3- propanetriol 2.99 7.11

9.21 Undecane - 3.91

9.32 1-ethyl-2-pyrrolidinone 10.38 -

10.08 2,2,5,5-tetramethyl-,3-cyclopenten-1-one - 5.15

11.42 1-butyl-, 2-pyrrolidinone, 4.25 2.72

12.93 1-pentyl-, piperidine 3.78 4.84

13.49 2-methyl-, 3-hydroxy-2,4,4- trimethylpentyl ester,

propanoic acid, - 5.11

24.91 Di(2-propylpentyl) ester , phthalic acid 10.78 -

Total 77.2 67.41 - , chemical compounds either not detected or peak area less than 2%.

Table 5.3 presents the variation of key chemical compounds from the biocrude

oil samples produced with a microalgae mass fraction in the feed ranging from 15%–

30% under various temperatures 280°C–350°C). The main compounds include:

nitrogenated compounds (pyrolle, pyrazine, piperidine); oxygenated compounds

(phenols, ketones, esters); aliphatics (alkanes, alkenes); and aromatics (benzene).


Table 5.3: Major compounds of recovered bio-oils obtained from HTL under various

solid concentrations and temperature using (DCM).

RT

(min) Name of compound

Area (%)

Slurry Concentration Temperature

15% 25% 30% 280

°C

300

°C

350

°C

4.01 2-methyl , pyrimidine 3.92 - 4.05 4.94 8.18 -

4.41 4-hydroxy-4-methyl , 2-

pentanone - 5.03 - 23.81 4.15 4.03

4.82 Ethylbenzene 0.68 8.86 - 1.34 1.75 8.86

4.97 1,4-dimethyl , benzene - 11.99 - 2.48 2.77 11.30

5.67 2-methyl , 2-cyclopenten-

1-one 4.71 - 2.72 9.19 10.03 -

5.79 2,5-dimethyl , pyrazine 4.84 4.09 3.53 12.18 12.4 4.09

6.8 3-methyl , 2-cyclopenten-

1-one 6.66 4.86 2.31 2.7 6.0 4.5

7.1 Phenol 3.24 3.33 2.16 - 2.43 3.32

8.15 2,3-dimethyl , 2-

cyclopenten-1-one 12.86 12.04 5.32 2.29 5.73 6.05

9.03 1- acetate 1,2,3-

Propanetriol, 4.72 5.09 5.63 2.58 4.22 5.19

9.27 Undecane 9.20 11.12 12.62 2.49 5.9 8.99

9.94 1,3-diethyl-3-methyl ,

2,5-pyrrolidinedione, 2.27 2.5 2.72 - 2.48 2.51

10.69 1-propyl , 2-

pyrrolidinone, 3.04 2.32 3.48 - - 2.30

11.39 1-butyl , 2-pyrrolidinone 3.3 4.25 3.16 - - 4.20

24.91 Di(2-propylpentyl) ester,

phthalic acid - 10.78 8.25 - - 10.78

- , chemical compounds either not detected or peak area less than 2%.

As shown in Table 5.3, cyclic oxygenated compounds (mostly ketones such as

2, 3-dimethyl, 2-cyclopenten-1-one), are slightly decreasing with increasing solids

concentration. This was in contrast to the aliphatic components, such as undecane,

which increased with the solid concentration. Cyclic nitrogenated and oxygenated

compounds including 1-butyl, 2-pyrrolidinone; 1, 3-diethyl-3-methyl, 2, 5-

pyrrolidinedione; 1-propyl, 2-pyrrolidinone were the most abundant in each sample.

In the low temperature reaction at 280 °C, biocrude oil had the highest amount of

oxygenated compounds—mostly aliphatic, prevalent ketones including 4-hydroxy-4-

methyl, 2-pentanone; 2-methyl, 2-cyclopenten-1-one; 2,3-dimethyl, 2-cyclopenten-1-

one. Abundance of HCs and aromatics were the lowest for the biocrude oil at 280 °C

but had the highest percentages at 350 °C. The number of identified nitrogenated


batch reactor 79

compounds such as pyrazine, 2-methyl, 2, 5-dimethyl, pyrimidine; trimethyl and

pyrazine, initially, increased with temperature and reached the maximum at 300 °C

after which it decreased. Jena et al. obtained similar results from biocrude oil

comparing five different temperatures [49]. Esters such as di (2-propylpentyl) ester,

phthalic acid; 15-methyl-, ethyl ester, heptadecanoic acid, were observed only in the

highest temperature. The detailed analysis shows the strong dependency of chemical

compounds on process condition.

5.3.5 Effect of temperature and concentration on chemical and physical

properties

Both the chemical and physical properties of biofuels are important to define

fuel quality in terms of combustibility, density, energy content, and lubricity. These

fuel properties vary with chemical composition and influence engine performance and

emission results [57, 73-77]. It was observed that the chemical components and

compositions of the biocrude varied with the process conditions (Table 5.2 and Table

5.3), which subsequently affected the fuel’s physical properties. Table 5.4 shows the

effect of temperature and concentration on ultimate analysis and HHV of the

microalgae biocrude. The chemical and physical properties of microalgae HTL

biocrude are shown in Table 5.5 and compared with FAME microalgae biofuel and

mineral diesel.

Biocrude chemical composition

The extracted biocrude contained a range of complex HC groups including

aliphatics, aromatics, as well as nitrogenated and oxygenated compounds. HCs mostly

contained either oxygen or nitrogen in the C-H chain. Table 5.4 shows the elemental

composition of the biocrude obtained at different temperatures with 25% slurry

concentrations and for different slurry concentration at 350 °C. The elemental analysis

showed that the mass percentage of oxygen decreased from 16% to 10% with

increasing temperature of the experiment for 25% slurry. In contrast, the hydrogen

percentage was relatively stable: within 8.93–10.14% over the experimental range. The

differences in chemical composition and molecular structure (e.g. C, H and O

composition, straight chain, cyclic, and heterocyclic compounds) affect the physical

properties of the biocrude oil including HHV, density, viscosity, cetane number and

surface tension; important parameters for internal combustion (IC) engines. The slow

heat-up and cooling-down time can potentially lead to polymerisation and secondary


reactions. It is expected that the engine performance and exhaust emissions would be

different compared to FAME biodiesel. For instance, the oxygen creates a permanent

dipole moment, which results in stronger hydrogen bonding and oxygenated fuels with

increased molecular affinity. Consequently, compressibility is decreased because the

free space between the molecules is similar. A follow-on effect is an increase in NOx

[74]. Nabi et al. [81] has also shown NOx emissions and adiabatic flame temperature

and NOx emissions present a linear decrease with increasing oxygen content.

Table 5.4: Ultimate analysis and HHV of the microalgae biocrude.

Component

(% wt.)

25% slurry concentration at

different temperature

350 °C temperature at

slurry concentration

280 ˚C 300 ˚C 350 ˚C 15% 25% 30%

C 68.1 70.4 75.6 74.1 75.6 73.7

H 9.3 8.9 10.1 9.7 10.1 9.8

O 15.7 12.1 10.3 11.2 10.3 10.8

N 6.9 8.6 4.0 5.0 4.0 5.7

H:C 0.14 0.13 0.13 0.13 0.13 0.13

O:C 0.23 0.17 0.14 0.15 0.14 0.15

N:C 0.10 0.12 0.053 0.07 0.05 0.08

HHV (Cal.), MJ kg-1 33.5 34.3 37.4 36.4 37.5 36.5

HHV(Meas.), MJ kg-1 -- 26.1 29.8 26.5 29.8 28.0

O:C, N:C and H:C significantly affect fuel quality and emissions, and so

temperature variation and slurry concentration effect on biocrude were compared with

diesel and FAME biodiesel standards in the Van Krevelen diagram (Figure 5.5). It is

important to note that the lowest N:C and O:C were found at the same conditions that

gave maximum biocrude yield and HHV (i.e. 350 °C and 25% slurry concentration;

for this range, the authors viewed lower O:C to be more beneficial). Figure 5.5 shows

that O:C changes with respect to N:C ratio, and H:C is almost constant; so N:C and

O:C varied more than H:C. The HHV is the highest at 350 °C due to the low O:C and

relatively good H:C. N:C also sharply reduced at high temperature. The biocrude oils

were more similar to FAME biodiesel than fossil fuel diesel in terms of H:C while the

nitrogen concentration was much higher than diesel and biodiesel standards due to the

high amount of proteins in the raw feedstock. We note that if n-hexane had been used

for the extraction rather than DCM the polarity of the biocrude would fall and

consequently the point would shift to the left on Figure 5.5 due to the lower oxygen

content.


batch reactor 81

Figure 5.5: Van Krevelen diagram of biocrudes gained for different temperatures

(280, 300 and 350 °C) and slurry concentrations (15%, 20% and 30%) in comparison

with diesel and FAME biodiesel standards [196].

The separated biocrude oil samples had a dark colour, high viscosity and an acrid

smoky odour. Chemical and physical properties were analysed for the optimal

biocrude produced at 350 °C, and 25% initial solids concentration and compared with

various types of fuel standards (Table 5.5).


Table 5.5: Comparison of chemical and physical properties of biocrude produced at

350 °C and 25% solids with trans-esterified microalgae biodiesel, diesel, biodiesel

and marine fuels standards [52].

Name of the

properties

HTL

Scenedesmus

sp. biocrude

oil

FAME

Crypthecodi

nium

cohnii

biodiesel

Biodiesel

Standar

ds

EN

14214

Petroleum

Diesel Marine

fuels

ISO

8217

Kinematic viscosity@40°

C (mm2 s-1)

70.7–73.8

5.06 3.5–5 2.64 1.4–

11.0

Density@15° C (kg L-1) 0.97* 0.91 0.86–0.9 0.84 0.96–

0.99

HHV (MJ kg-1) 29.7 39.8 - 44 44–45

Oxygen content (wt. %) 10.3 10.4 - 0 -

Hydrogen Content (wt. %) 10.1 11.1 - 13.8 -

Carbon Content (wt. %) 75.5 78.4 - 86.1 -

Nitrogen Content (wt. %) 3.97 0 - 0 -

Viscosity

At the optimum conditions, the viscosity of the HTL microalgae biofuel was

closer to conventional diesel and biodiesel than FAME from microalgae and varied

with chemical composition, possibly due to the varying degree of chemical saturation

[197]. The variation of biocrude compositions influenced the intermolecular forces.

The variation in viscosity can potentially affect injection timing, spray, atomisation

and combustion compared to microalgae FAME [180]. There is a possibility to use

biocrude in a heavy-duty diesel engine or a marine-ship engine with minimal

upgrading.

Density

The fuel density affects the mass of fuel injected because fuel injection systems

in modern diesel engines measure the fuel on a volume basis [74]. At optimal

conditions, the density of the HTL microalgae biocrude was 13% higher than

conventional diesel fuel and not comparable with any fuel standards in Table 5.5. The

increased density of the HTL microalgae biocrude might be due to it containing many

aromatic HCs and cyclic chemicals as well as an amount of high molecular weight

compounds that are beyond detection in GC-MS. However, the density value (0.97


batch reactor 83

kg.L-1) is comparable to the marine residual fuel standard ISO 8217:2012 (0.96–0.99

kg.m-3).

HHV

Among the fuels, the HHV of microalgae biocrude had the lowest value at 29.8

MJ.kg-1 (best H:C) [24]. Enrichment in double bonds generally results in lower than

expected levels of heats of combustion due to strong intra-molecular bonding [198].

The vapour heat capacity and thermal conductivity relates to the heating value of the

fuel. These affect droplet-surrounding heat transfer, temperature distribution and the

mass air fuel ratio that will reduce combustion performance [199].

5.3.6 Comparison with previous studies

The findings of this study are compared with previous studies in Table 5.6 where

most researchers worked with very small-batch reactors (<100 ml), although there

have been a few studies with larger continuous reactors (typically ~1000 ml). The vast

majority of HTL studies report physical properties, HHV in particular, derived from

correlations, which use elemental analysis results for gaseous, liquid, coal and biomass

materials [187, 190]. Our calculated values for HHV are similar to those reported

elsewhere but we also report a much lower measured value, which was also reported

by Li [93], despite the different oxygen content.

The density and viscosity of the biocrude are not widely reported (Table 5.6).

The biocrude viscosity was significantly closer to regular diesel and biodiesel

standards than transesterified (FAME) microalgae biodiesel. Under optimised

conditions, HTL biocrude’s high density (0.97–1.04 kg L-1) and its high viscosity

(3.61–3.37 mm2 s-1) had enough similarity to marine heavy fuels that it could be

immediately used without further processing, although the measured HHV was lower

(29.8 MJ kg-1).


Table 5.6: Comparison of results from this study with literature.

HTL biocrude

Reactor type

Reactor volume (ml)

Operating conditions

Physicochemical properties

Temp. (°C)

Time (min)

Yield wt %

Chemical composition % HHV (MJ/kg) Kinematic viscosity (mm2/s)

Density (kg/L)

Refer-ences

C H N O Calcu- lated

Meas- ured

Scenedesmus sp.

Batch reactor

1800 350 60 33.6 75.6 10.1 3.97 10.3 37.4 29.8 70.7–73.8 0.97 Current study

500 300 30 45 72.6 9.0 6.5 10.5 35.5 - - - [200]

Enteromorpha prolifera

25 300 30 23 64.5 7.7 5.4 22.4 30.8 - - - [50]

Lemna sp. 25 350 30 17.5 72.1 7.8 4.6 15.5 32.8 - - - [95]

Laminaria saccharina

75 350 15 19.3 82.0 7.1 4.9 6.0 37.4 - - - [72]

Chlorella pyrenoidosa

17.2 350 60 41 75.1 9.9 7.3 7.7 38.1 - - - [94]

Nannochloropsis sp

35 350 60 43 76.0 10.3 3.9 9.0 39 - - - [183]

Enteromorpha prolifera

25 370 40 31.7 77.9 9.6 5.6 6.9 39.4 - - - [51]

Sargassum patens C. Agardh

1000 340 10 32.1 64.6 7.4 2.5 25.5 - 27.1 - - [93]

Saccharina sp. Continuous-flow reactor

1000 340 87 58.8 79.4 8.0 4.1 8.5 37.5 - - - [53]

NB238 1000 350 38 78.6 10.4 4.2 5.3 - - - - [201]


batch reactor 85

5.4 CONCLUSION

This paper studied the impact of HTL operating conditions (reaction temperature

and slurry concentration) on the chemical compositions and the subsequent physical

and chemical properties of the microalgae biocrude. Physical properties were able to

be measured experimentally because of the larger scale of the reactor rather than being

derived using correlations based on elemental analysis. We note a significant

difference in the calculated and measured values, which is consistent with the

literature. The highest biocrude oil yield (33.6%) was produced at 350°C and at 25%

solids concentration. The aliphatic, aromatic, nitrogen-containing hetero-cyclic,

oxygenated compounds were the major group of components of HTL microalgae

biocrude. These conditions also produced the lowest O:C and N:C. The biocrude had

higher density and lower HHV than diesel and biodiesel and was closer in character to

HFO where it could be used directly. Future work will focus on further improving

chemical and physical properties, such as HHV, density, and decreasing N and O

percentages, via catalytic upgrading, or via reactions in-situ, followed by engine

testing.


5.5 ACKNOWLEDGMENTS

This work was financially supported by the QUT ECARD program and by a PhD

scholarship from the QUT School of Chemistry, Physics and Mechanical Engineering.

The authors thank to the QUT Central Analytical Research Facility for their assistance.

Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions

using surrogate fuels 87

Chapter 6: Investigation of microalgae

HTL fuel effects on diesel

engine performance and

exhaust emissions using

surrogate fuels

Farhad M. Hossain1, 2*, Md. Nurun Nabi3, Thomas J. Rainey1, 2, Timothy Bodisco4,

Md Mostafizur Rahman5, Kabir Suara1, Rahman S.M.A 1,2, Thuy Chu Van 1,2, Zoran

Ristovski1,2 and Richard J. Brown 1, 2,

1 Biofuel Engine Research Facility, Queensland University of Technology (QUT), Brisbane,

Queensland 4001, Australia 2 QUT, International Laboratory for Air Quality and Health 3 School of Engineering and Technology, Central Queensland University, Perth, WA 6000, Australia. 4 School of Engineering, Deakin University, Waurn Ponds, Victoria 3217, Australia 5 Rajshahi University of Engineering & Technology, Department of Mechanical Engineering,

Bangladesh












Title and status: Investigation of microalgae HTL fuel effects on diesel engine

performance and exhaust emissions using surrogate fuels (Published at Energy

Conversion and Management-under review).





the results, wrote the manuscript and acted as the corresponding author.

Signature

Date

Richard Brown Principal Supervisor

Conceptualised the design of instrument, aided the field experiments,

interpretation of the results, reviewed and edited the manuscript as a

principal supervisor.

Md Nurun Nabi Dr Md Nurun Nabi has been working as a Lecturer in the Department of

Mechanical Engineering at Central Queensland University (CQU), . He

has about 30 years of research experience in the field of engine exhaust

emissions.

Describe physicochemical properties effect of engine performance and

edited the manuscript.

Thomas Rainey Dr Thomas Rainey has 15 years of industrial and research experience in



Design concept of surrogate fuel and edited the manuscript.

Timothy Bodisco Dr Tim Bodisco has been working as a lecturer in the Department of

Mechanical Engineering at Deakin University. He has extensive

experience in engine experimental data analysis.

Dr Bodisco assisted in the analysis of cylinder data using his own matlab

code and edited the manuscript.

Md Mostafizur Rahman Dr. Md Mostafizur Rahman has been working as a Lecturer in the

Department of Mechanical Engineering at Rajshahi University of

Engineering & Technology.

Dr Md Mostafizur Rahman assisted with conducting the experiments.

Kabir Suara Dr Kabir Suara has been working as a Research Fellow at Queensland

University of Technology.

Dr Kabir assisted to analysis the data using matlab.

Rahman S.M.A Mr Ashrafur Rahman helped to conduct the engine experiment, especially

for PN measurements.



Thuy Chu Van Mr Thuy Chu Van helped to conduct the engine experiment, especially for

PM measurements.

Zoran Ristovski Professor Zoran Ristovski is a physicist who works at the Queensland



Professor Zoran Ristovski designed and performed fuel properties related

to engine exhaust emissions and reviewed the manuscript as a co-authors.


I have sighted email or other correspondence from all Co-authors confirming their certifying

authorship.


Name Signature Date


Abstract

This paper builds on previous work using surrogate fuel to investigate advanced

internal combustion engine fuels. To date, a surrogate fuel of this nature has not been

used for microalgae hydrothermal liquefaction (HTL) biocrude. This research used

five different chemical groups found in microalgae HTL biocrude to design a surrogate

fuel. Those five chemical groups constitute around 65% (by weight) of a microalgae

biocrude produced by HTL. Weight percentiles of the microalgae HTL biocrude

chemical compounds were used to design the surrogate fuel, which was miscible with

diesel at all percentages. The engine experiments were conducted on a EURO IIIA

turbocharged common-rail direct-injection six-cylinder diesel engine to test engine

performance and emissions. Exhaust emissions, including particulate matter (PM) and

other gaseous emissions, were measured with the surrogate fuel and a reference diesel

fuel. Experimental results showed that without significantly deteriorating engine

performance, lower PM, PN and CO emissions were observed with a penalty in NOx

emissions for all surrogate blends compared to those of the reference diesel.

Keywords: Microalgae, surrogate fuel, diesel engine, emissions, PM, PN, NOx and

CO.



6.1 INTRODUCTION

Alternative fuels have become a key issue in the modern world due to the

depletion of fossil-fuel reserves, increasing fuel prices and issues relating to exhaust

emissions. Compared to petroleum diesel, biofuel has some advantages in relation to

emissions, including low emissions of carbon monoxide (CO), particulate matter and

unburned hydrocarbons (HCs) [31]. Hence, researchers have focused on the

development of biofuel and associated upgrading to meet fuel standards without

compromising engine durability [44, 45]. Many groups have investigated novel uses

of biofuel in diesel engines [6, 11, 65, 202, 203]. Unfortunately, most biofuels are not

able to be produced at an industrial scale. This is chiefly due to high production costs

and the fact that fuel properties may not be suitable for use in current diesel engines

due to their physiochemical properties. However, microalgae has recently received a

lot of attention as one option for producing biofuel as a renewable energy source

because it has minimal adverse effects on food supply and other agricultural systems

[10, 32, 204, 205]. Microalgae may be a potential feedstock for biofuel based on its

lipids and HCs [2, 206]. Various conversion techniques have been used to generate

biofuel from microalgae, including solvent extraction and hydrothermal liquefaction

(HTL) [32, 47, 180, 207].

HTL methods are gaining interest for producing biocrude. In liquefaction

methods, biomass is changed into gas, liquid and solids in a similar manner to

pyrolysis [48]. HTL is the most energetically advantageous thermochemical biomass

conversion process and it has been investigated with a wide range of microalgae

biomass feedstocks, including laboratory and commercially-grown strains

Botryococcus braunii [55], Spirulina and Tetraselmic sp. [32, 47]. Jena et al. [49]

studied the production of biocrude from Spirulina platensis. However, biocrude has a

higher oxygen and nitrogen content compared to reference diesel. In addition, HTL

biocrude contains inorganic salts and metals, which pose challenges within the

traditional refining process [32, 55, 72].

Therefore, microalgae-based biocrude requires further processing to improve

quality by reducing these undesired components. Chemical analysis of microalgae

biocrude reveals the presence of many chemical compounds in small quantities.

However, five chemicals contribute around 65% (wt.) of the total weight. In this study,

those five chemicals were blended to produce a surrogate fuel.


Surrogate fuels are not new. Many researchers have developed diesel surrogate

fuels using various techniques [208-212]. Surrogates of diesel fuels are useful design

tools for developing engines with cleaner and more efficient combustion [212]. A

surrogate fuel is a mixture of pure chemicals to mimic the physicochemical properties

of a target fuel. Both physical and chemical fuel properties should be matched to the

surrogate fuel because those properties are important for engine operation,

performance and exhaust emissions. The chemical characteristics of the fuel include

molecular structure, flash point and C/H/O ration whilst physical characteristics

include HHV, density, viscosity and surface tension [208].

Pitz and Mueller [208] reviewed recent progress in the development of diesel

surrogate fuels. They investigated the status of chemical kinetic models and

experimental validation data of surrogate fuel components. They concluded that the

presence of higher molecular weight components is needed in models and

experimental investigations of surrogate fuel [208]. Dooley et al. [213] formulated a

jet surrogate fuel by real fuel properties. They used three chemical compounds—n-

decane, iso-octane and toluene mixture of 42.67, 33.02 and 24.31 (mol%)—to obtain

target surrogate properties [213]. Liu et al. [210] experimentally and numerically

investigated the combustion and emissions characteristics of diesel surrogate fuels in

a diesel engine. They investigated three different surrogates, including 85% (vol.) n-

heptane blended with 15% toluene (T15), 81% n-heptane blended with 14% toluene

and 5% c-hexane (T15 + CH5), and 80% (vol.) n-heptane blended with 20% toluene

(T20). They found the NOx and soot emissions were reasonably predicted. From the

modelling investigations, they inferred that the effects of physical properties on the

soot emission were larger than the effects of chemical properties of the different fuel

carbon-chain structures [210]. Das et al. [212] investigated sooting tendencies of diesel

fuels, jet fuels, and their surrogates in a diesel engine. They reported the opportunity

for developing new surrogates, composed of HCs with well-studied chemistry, which

can be used to replicate the sooting behaviour of most fuels [212]. Wu et al. [211]

experimentally investigated the miscibility of hydrogenated biomass-pyrolysis oil with

diesel as surrogate-ethylene glycol and its applicability to diesel engines. They found

that only 10% volume ethylene glycol could be mixed with diesel. They also reported

that there was no significant difference in specific fuel consumption, but found a

reduction in soot emissions [211]. Abboud et al. [214] tested the effect of the



concentration of oxygenated compounds on sooting propensities of surrogate diesel

and biodiesel. They found different behaviour for soot generation in both surrogate

diesel and biodiesel. They also reported that biodiesel-derived soot was smaller and

less reactive than diesel-derived soots [214].

The objectives of this study were to comparatively investigate the engine

performance and exhaust emissions of a series of microalgae HTL surrogate fuels on

a common-rail, multi-cylinder, turbo-charged diesel engine. The significance of this

research is to determine the thermal efficiencies and exhaust emissions of a new

surrogate fuel in a commercial diesel engine and establish a non-conventional fuel

application in a regular engine without modification. The performance of the engine

output is presented in terms of in-cylinder pressure and volume, brake power (BP),

brake mean effective pressure (BMEP), brake thermal efficiency (BTE) and brake-

specific fuel consumption (BSFC). Gaseous emissions of nitrogen dioxide (NO2),

nitrogen oxide (NOx), CO, particulate matter (PM) and particulate number (PN) were

compared.

To the authors’ knowledge, no investigation has been performed using a

microalgae HTL biocrude surrogate fuel to investigate performance and exhaust

emissions. This research will also provide fundamental knowledge for developing

microalgae biocrudes.

6.2 CONCEPT OF MICROALGAE HTL SURROGATE

In earlier experimental work, microalgae biomass were used to produce biocrude

using a HTL method. Two different variables were used as operating conditions:

temperature and slurry concentration. It was found that 25% slurry concentration and

350 ⁰C provided the best operating conditions. Further detail of the microalgae

biocrude operating conditions can be found in Farhad et al. [215]. It was also found

that microalgae HTL biocrude contains 13 main chemical compounds, seven of which

constitute 65% (wt.) of the total weight (i.e. under operating conditions with 25%

slurry concentration and 350⁰C) [215]. Those seven chemical compounds are

ethylbenzene, 1, 4-dimethyl-benzene, 3-methyl-2-cyclopenten-1-one, 2, 3-dimethyl-

2-cyclopenten-1-one, undecane, 4-hydroxy-4-methyl-2-pentanone and di(2-

propylpentyl) ester. These chemical compounds also contain key functional groups

present in the biocrude, including aromatics, cyclic ketones, alkanes, alcohols, and

aromatic FAMEs as shown in Figure 6.1 (results in duplicate). The horizontal red line


drawn at 5% (wt.) is used for illustrative purposes to elucidate which chemical

compounds are present at levels above 5%. Figure 6.2 shows the proportion of

compounds in microalgae HTL biocrude by functional group.

Figure 6.1: Weight percentage of chemical compounds in microalgae HTL biocrude.

Figure 6.2: Major chemical compounds of microalgae HTL biocrude [215].

6.2.1 Chemical compound for surrogate fuel

Each section of the surrogate palette is referred to as a surrogate chemical

compound. The surrogate chemical compounds were selected based on five key

0

5

10

15

% o

f H

TL

bio

-cru

de c

om

pou

nd

s

25% Slurry concentration @ 350 C_1

25% Slurry concentration@ 350 C_2

AlkaneCyclic ketone Aromatic FAMEAromatic Alcohol

Aromatics21%

Cyclic ketone17%

Alkane11%

Alcohel5%

Aromatic FAME11%

Others35%



functional groups: aromatics, cyclic ketones, alkanes, alcohols, and aromatic FAMEs.

Each are described in detail below.

Aromatics

Petroleum-based diesel contains around 25% of aromatic HCs [216]. They have

an impact on the cetane number and exhaust emissions of diesel engines, which means

improved engine performance. Aromatic HCs increase diesel engine particulate

emissions, which has long been of concern due to the toxic composition of the

emissions and the particle size distribution [217, 218]. Small, fine particles are

inhalable and penetrate deep into the lungs where they are able to enter the bloodstream

and even reach the brain [217, 219]. However, microalgae HTL biocrude contained

two aromatics in large quantities: 1, 4-dimethyl-benzene; and ethylbenzene. Their

chemical structures are shown in Figure 6.3 (a) and (b). Two methyl groups or an ethyl

group are attached to benzene. They are all colourless, flammable liquids.

(a) (b)

Figure 6.3: Chemical structure of (a)1,4 dimethyl, benzene and (b) Ethylbenzene.

Cyclic ketone

Two ketones (cyclic and straight chain) were found in microalgae HTL biocrude

in significant quantities. Figure 6.4 (a) and (b) shows cyclic ketone 3-methyl, 2-

cyclopenten-1-one, and 2, 3-dimethyl, 2-cyclopenten-1-one, which is contained in

microalgae HTL biocrude. However, both cyclic ketones are very expensive for the

purposes of engine testing, so cyclopentone (shown in Figure 6.4 (c)) was used instead

due to its functional similarity and low cost. It is also a colourless liquid with a petrol-


like odour. Cyclopentene is produced industrially in large amounts. It is used as a

monomer for synthesis of plastics, and in several chemical syntheses.

(a) (b) (c)

Figure 6.4: Chemical structure of (a) 3-methyl, 2-cyclopenten-1-one, (b) 2,3-

dimethyl, 2-cyclopenten-1-one and (c ) Cyclopentene.

Alkane

The majority of diesel fuel is made up of alkanes. Alkanes are straight-chain and

single carbon-carbon bond HCs. Petroleum-based diesel is composed of 75% saturated

HC, which are alkanes [216]. They are stable chemical compounds compared to

double- or triple-bond HC, which is called alkene and alkaline respectively. Straight-

chain alkanes are usually gaseous at room temperature; those with five to 15 carbon

atoms are usually liquids. The microalgae HTL biocrude contain about 11% (wt.)

undecane of the total biocrude weight. This chemical is low cost and can readily be

obtained. The chemical structure of undecane is shown in Figure 6.5.

Figure 6.5: Chemical structure of undecane.

Alcohol

The chemical compound 4-hydroxy-4-methyl-2-pentanone was found in the

microalgae HTL biocrude in significant quantities. This chemical contains both ketone

and hydroxide groups. It is also expensive. The chemical’s structure is shown in Figure

6.6 [220]. Butanol was selected to represent the alcohol group which occurs on a

number of biocrude compounds including (4-hydroxy-4-methyl-2-pentanone and 1-



acetate 1,2,3-propanetriol). Butanol is readily available and at a suitable cost compared

to 4-hydroxy-4-methyl-2-pentanone.

(a) (b)

Figure 6.6: Chemical structure of (a) 4-hydroxy-4-methyl and (b) butanol.

Aromatic FAME

The microalgae HTL biocrude contains a very irregular type of fatty acid methyl

ester (FAME): di-(2-propylpentyl) ester. This FAME contained aromatic ring in their

chemical structure, which is shown in Figure 6.7. In general, these compounds have

low toxicity.

Figure 6.7: Chemical structure of di-(2-propylpentyl) ester.

6.2.2 Design of microalgae HTL surrogate

There have been numerous engine studies using diesel surrogates [208-212,

214]. Most previous studies have involved up to six components [209, 211, 212]. The

current study provides a methodology for creating microalgae HTL surrogate fuel.

HTL microalgae biocrude contains many different chemical compounds from different

chemical groups. In addition, HTL biocrude contains inorganic salts and metals, which

bring challenges to the traditional refining process [32, 55, 72]. Therefore, the biocrude

requires further processing to improve quality by reducing these undesired


components. It is also noted that biocrude physicochemical properties are not similar

to regular diesel fuel, thereby preventing it being used directly in conventional diesel

engines (as a neat fuel). The approach for designing the target surrogate fuels with the

chemical groups is shown in Figure 6.8, while the final palette is shown in Figure 6.9.

The physicochemical properties of the target fuels were taken into account as design

parameters and the percentage of different chemical groups was decided according to

literature [208, 209]. The target fuel is a theoretical fuel with selected properties that

are to be matched by a surrogate fuel. Similarly, the design properties are the properties

of the target fuel that are to be matched by the surrogate fuel. The design properties

included CN, HHV, density, and the chemical composition of the fuel. The property

target for CN was 45 and 0.82–.084 (kg/L) for density. However, the reference

chemical groups were selected from the microalgae HTL biocrude list, which is shown

in Figure 6.1. The surrogate fuel properties are shown in Table 6.3 and compared to a

reference diesel fuel.

Microalgae HTL biocrude contained about 4% (wt.) nitrogen based on a selected

operating condition [215]. However, there are two reasons that the nitrogen was not

used in the surrogate fuel: (i) the chemical compounds considered were those having

above 5% weight percentages in the biocrude; and (ii) in general, it is very uncommon

for nitrogen to be in fuel. However, nitrogenated components in the fuel could be

another area for future research to explore. The behaviour of multi-component fuels is

more complicated than single-component fuels because of the potential for chemical

interactions. Though, these chemical compounds come from a relatively stable

microalgae HTL biocrude so these interactions in the surrogate fuel were presumed to

be realistic.



Selected palette for design fuel

Blend selected palette base

on design properties

Measure design properties

of surrogate fuel

Achieved target fuel

properties?

Y

Surrogate

fuel complete

Change selected

chemicals proportion

N

Design fuel

Select the design properties

and target

Measure and analysis physicochemical

properties of palette: chemical

composition, density, viscosity and HHV

Stop

Figure 6.8: Proposed roadmap for development of microalgae HTL surrogate fuels.

Figure 6.9: Percentage of chemical compound of a new microalgae HTL surrogate.

Aromatics20%

Cyclic ketone15%

Alkane45%

Alcohol10%

Aromatics FAME10%


The microalgae HTL surrogate fuel (100%) was blended with the reference

diesel at three different percentages: 10%, 20% and 50%.

Sur-10 Sur-20 Sur-50

Figure 6.10: Blended microalgae HTL surrogate for engine test.


The experiments were conducted in the Biofuel Engine Research Facility

(BERF) at QUT with a EURO IIIA heavy-duty diesel engine using surrogate blends

and neat diesel fuel (100%). The engine was operated at a constant speed of 1500 rpm

(maximum torque speed) at four different loads: 25%, 50%, 75% and 100% of full

load. Maximum load at any engine speed depends on the type of fuel used, therefore

the maximum load for each fuel was determined when the engine was at full throttle

at 1500 rpm.

All experiments were conducted in a common-rail six-cylinder, turbo-charged

and after-cooled diesel engine with the specifications listed in Table 6.1. The engine

had a capacity of 5.9 L, maximum torque of 820 Nm at 1500 rpm and maximum power

of 162 kW at 2000 rpm. This engine was not fitted with any exhaust gas recirculation

(EGR). Each cylinder had four valves, two of them for inlet and two of them for

exhaust. The engine was coupled with a water-based dynamometer.

Diesel

Surrogate



Figure 6.11 shows the schematic of the experimental engine setup. Further detail

of the engine configuration and instruments can be found in Bodisco and Brown [221].

Table 6.1: Test engine specification.

Physicochemical properties of pure chemical compounds of surrogate fuel and

its blends are shown in Table 6.2 and Table 6.3 respectivey. The first row of Table 6.3

shows the name of the four different fuels 100D, 90D10S, 80D20S, and 50D50S

classified by the volume of each fuel. The Microalgae HTL surrogate was in colour

less with recognisable odour. The physicochemical properties of the reference diesel

and 100% surrogate fuel were experimentally measured. The properties of the blends,

including 90D10S, 80D20S, and 50D50S, were calculated proportionally based on the

neat fuel properties shown in Table 6.3 [3, 57]. Conversely, CN of the surrogate

chemical compound was found from published results, which are shown in Table 6.2.

CN for a few of the surrogate chemical compounds could not be found in the literature.

Therefore, an almost similar chemical compound for CN was used and is described

here. The CN for aromatic HC 1,2-dimethylbenzene is 8.3, which is part of the xylene

compound [222]. Xylene was used as a chemical compound of surrogate fuel, which

is a mixture of o-xylene, m-xylene, and p-xylene. The exact CN of xylene was

unknown. Likewise, the CN of cyclohexanone was unknown so the CN of

cyclopentanone, which is 10, was used instead. The CN for dihexyl phthalate was used

instead of dioctyl phthalate (DOP) due to an almost identical chemical structure [222].

Figure 6.11 shows a schematic diagram of the experimental set up for diesel-

engine performance and exhaust-emissions measurement. The engine performance

data, including in-cylinder pressure, diesel injection timing and degrees of crank angle

Model Cummins ISBe220 31

Cylinders 6 in-line

Capacity 5.9 L

Bore x stroke 102 x 120 (mm)

Maximum power 162 kW @ 2500 rpm

Maximum torque 820 Nm @ 1500 rpm

Compression ratio 17.3:1

Aspiration Turbocharged

Fuel injection High-pressure common rail

Dynamometer type Electronically-controlled water brake dynamometer

Emission standard Euro IIIA


rotation, were recorded. Indicated work (IW) was calculated by integrating a pressure

vs volume diagram using the trapezoid rule. Further detail of the engine performance

measurements can be found in Bodisco and Brown [221]. Different exhaust gas

measuring instruments, including DMS500, DustTrak (Model 8530), SABLE (CA-10)

and CAI 600, were used for emissions measurements. The DMS500 (Cambustion Ltd.)

is uniquely suited for a variety of diesel particulate filter applications. CAI 600 series

analysers were used to measure the raw exhaust gases CO, CO2, NO and NOx, and

Sable and DustTrak were used to measure diluted CO2 gas and particulate mass

respectively. Both DMS500 and DustTrak were used for measurement of PN and PM.

Further detail of the engine exhaust emission measurements can be found in Rahman

et al. [57]. All measurements were repeated three times, and the repeatability was

quantify by calculating the standard deviation and this is shown (Figure 21, 22, 24 26

and 28) as ±1σ standard deviation.

Table 6.2: Properties of diesel and surrogate chemical compounds.

Properties

Methods

Diesel

Chemical Groups

Aromatic Cyclic ketone

Alkane Alcohol Aromatic

FAME

Chemical compounds

Xylene Cyclopen-tanone

Undecane Butanol Dioctyl- pathalate

Surrogate composition (% wt)

20 15 45 10 10

Density (kg/L)1 ASTM D4052 0.84 0.84 0.92 0.77 0.81 0.96

K. Viscosity (mm2/s)1

ASTM D240

2.66 1.39 1.70 1.89 2.57 27.40

HHV (MJ/kg)1 ASTM D240 45.64 42.41 34.09 46.24 36.2 35.7

LHV (MJ/kg) --- 43.95 40.48 32.14 43.09 33.43 33.70

Surface tension1 --- 26.77 27.44 29.89 25.17 25 30.55

Carbon (%wt.)2 --- 91.66 90.5 71.37 84.51 64.79 73.79

Hydrogen (%wt.)2 --- 8.34 9.5 9.59 15.49 13.61 9.81

Oxygen (%wt.)2 --- 0 0 19.04 0 21.59 16.4

C:H --- 10.99 9.52 7.44 5.45 4.76 7.52

Flash point (°C)3 ASTM D93 67.5 25 30 70 35 207

Cetane index ASTM D4737A

51.744 8.35 107 795 177 485

1- Measured at QUT, 2- Calculated, 3- Chemical certificate, 4- Caltex fuel certificate, 5-

Blend methods, 6- ASTM D613 (CFR), 7- Unknown methods.



Table 6.3: Properties of diesel, surrogate and surrogate blends.

Properties Methods 100D 100S 90D10S 80D20S 50D50S Biodiesel

Standard

ASTM

6751-12

Density(Kg/L)1 ASTM D4052 0.84 0.83 0.84 0.84 0.84 0.86-0.9

HHV(MJ/kg)1 ASTM D240 45.64 42.34 45.2 44.83 43.62 --

LHV(MJ/kg)2 -- 43.95 39.77 42.45 42.07 40.93 --

K. viscosity (mm2/s)2 ASTM D445 2.66 4.38 2.83 3.00 3.52 1.9-6.0

Lubricity (mm)3 IP 450 0.412 -- -- -- --

Carbon (% wt.)2 -- 87 80.69 85.59 85.04 83.41 --

Hydrogen (%wt.)2 -- 13 12.65 13.75 13.62 13.26 --

Oxygen (%wt.)2 -- 0 6.65 0.67 1.33 3.33 --

C:H2 -- 6.69 6.38 6.23 6.24 6.29 --

Flashpoint (°C)2 ASTM D93 68.66 65.2 67.27 67.04 66.35 130

Cetane index3 ASTM

D4737A

51.74 45.212 51.092 50.432 48.472 7 min

1- Measured at QUT, 2- Calculated, 3- Caltex fuel certificate


Compressed Air

SABLE CA-10Dust Track

Diesel Engine Exhaust emissions flow Diluted exhaust flow

CAI gas analyser

Engine control roomEngine room

DMS500

Figure 6.11: Schematic diagram of the engine exhaust measurement system used for

this study.


This section describes the engine performance and exhaust emissions using

microalgae HTL surrogate blends, as well as comparisons of their individual

measurements. The engine performance parameters, including BP, IP, IMEP, BSFC,

ISFC, BTE, and ITE, in-cylinder pressure and volume, are presented in separate

Figures. The properties of microalgae HTL surrogate fuels were measured and

calculated and were found to be close to those of diesel fuel. It is generally accepted

that the fuel properties influence the fuel-spray characteristics, fuel evaporation, the

formation of fuel droplet size, distribution of fuel atoms and, therefore, the exhaust

emissions.

6.4.1 Engine performance

The indicated power (IP) of an engine is the power produced by the combustion

products on the piston in the cylinder. Conversely, the BP is the useful power at the

output shaft. The IP and BP variations with engine load are shown in Figure 6.12. It

was observed that both IP and BP linearly increased with increasing engine load for



the reference diesel and surrogate blends. The difference between the IP and BP

reduced as the load increased, indicating a reduction in friction power. This is

consistent with other research findings [218, 220]. On this engine, the maximum IP

for 100% of full load for reference diesel is 130 kW. A very small changes in either IP

or BP among the fuels were observed. This is most likely due to the close calorific

value of microalgae HTL surrogate blends compared to that of reference diesel.

Figure 6.12: IP and BP variation with IMEP for different fuels.

Figure 6.13 shows the BTE and BSFC, which are calculated using equations

(6.1) and (6.2), respectively. BTE can be defined as the BP of a heat engine as a

function of the thermal input from the fuel. BTE is used to measure how mechanically

efficient an engine is at converting the chemical energy of fuel to useful mechanical

energy [5]. It was observed that BTE reached a maximum (38%) at around 50% load

for all fuels. This is consistent with other published results [220, 221, 223]. . Compared

to diesel use of a surrogate blend results in a slight decrease in BTE for all engine loads

which is greatest for 50S50D. The reduction in BTE with surrogate blends is due to

the lower heating value of the surrogate blends.

BSFC is a measure of the fuel effectiveness of an engine that burns fuel and

produces power. It is typically used for comparing the efficiency of engines with


output power and represents the ratio between the rate of fuel consumption and the BP.

Compared to diesel use of a surrogate blend results in a slight increase in BSFC for all

engine loads which is greatest for 50S50D. The variation between BSFC for the

reference diesel and for the blends was in the range of 217–225 g/kWh across all loads.

Zare et al. [80] reported similar variation of results. It is revealed from Figure 6.13 that

BTE and BSFC have a reciprocal relationship. While BTE decreases with increasing

IMEP, BSFC increases with increasing engine load for reference diesel and their

blends.

𝐵𝑇𝐸 =𝐵𝑃∗100

Mf ∗ 𝐿𝐻𝑉 --------------------------------------------------- (6.1)

𝐵𝑆𝐹𝐶 =3600∗𝑀𝑓∗1000

BP ------------------------------------------ (6.2)

Where BTE in % and BSFC in g/kWh, BP in kW, Mf is the mass-flow rate of fuel in

kg/s, and LHV is the lower heating value of fuel in MJ/kg.

Figure 6.13: BTE and BSFC variation with IMEP for different fuels.



Figure 6.14: ITE and ISEC variation with IMEP for different fuels.

ISFC and ITE were calculated using equations (6.3) and (6.4). The ITE is a

dimensionless performance-measuring parameter, which gives an idea of the power

generated by the engine with respect to the heat supplied. As illustrated in Figure 6.14,

ITE was almost the same for all tested fuels. The ITE reduced gradually with an

increase in engine load for both blended fuels, which is consistent with other published

results [224]. On the other hand, ISFC results indicate that the fuel efficiency of the

engine is affected with respect to thrust output. Figure 6.14 also shows that ISFC

slightly decreased with increasing engine load but stayed almost the same for all tested

blends. This indicates that there was no change in the fuel efficiency when using

microalgae HTL surrogate blends compared to reference diesel fuels. This could be

due to the fuel’s heating value, surface tension and density, which are almost the same

as the reference diesel, as shown in Table 6.3.

𝐼𝑇𝐸 =𝐼𝑃∗100

𝑀𝑓∗𝐿𝐻𝑉 ------------------------------------------------- (6.3)

𝐼𝑆𝐹𝐶 =3600∗𝑀𝑓∗1000

IP ---------------------------------- (6.4)


To minimise the effect of cycle-to-cycle variations, the in-cylinder pressure data was

recorded for 750 consecutive cycles and the mean was taken to plot Figure 6.15 to

Figure 6.18. The peak in-cylinder pressure with the reference diesel was found to be

11 MPa, which is the highest among the fuels, while 50D50S produced the lowest.

Variation of in-cylinder pressure (P) with respect to the crank angle (CA) for different

fuels, including 90D10S, 80D20S, 50D50S, and 100D, are shown in Figure 6.15 and

Figure 6.16 for 100% and 50% load respectively. The lower in-cylinder pressure with

surrogate blends is due to lower energy content (HHV) of the fuel. Conversely, for

both loads (100% and 50%), the surrogate fuels showed lower pressure peaks than the

reference diesel. Both loads in Figure 6.16 showed two pressure peaks, one near the

TDC and the other in the expansion stroke for all fuels, and were dominant for 50%

load. The dominant pressure peak for 50% load at the expansion stroke needs further

investigation.

The in-cylinder volume is a function of the crank angle so that it is possible to relate

the cylinder pressure to cylinder volume, which is depicted in the PV diagram shown

in Figure 6.17 and Figure 6.18 for 100% and 50% of full load respectively. When the

piston is at bottom dead centre (BDC), the cylinder will have its largest volume. As

the piston moves up to the top dead centre (TDC), the volume is reduced to a minimum.

No significant variation in pressure was observed with respect to cylinder volume for

all blends, which is consistent with the pressure versus crank-angle curve. Combustion

resonance with a frequency of ~6000 Hz was observed in both Figure 6.17 and Figure

6.18. This resonance has been investigated in detail by Bodisco et al. [30].



Figure 6.15: Variation of pressure with crank angle for 100% load for different fuels.




Figure 6.19 shows the peak pressure and rate of pressure rise versus engine load

for the four fuels. Although surrogate blends showed lower peak pressure, the

reduction was small. In regards to maximum pressure rise rate, compared to the

reference diesel, all surrogate blends showed a higher maximum pressure rise rate.

This could be due to the lower CN in the surrogate blends and warrants further

investigation. The highest peak pressure and boost pressure were found to be around

11,000 kPa and 245 kPa respectively for 50D50S, which may pose a concern for

engine vibration and wear (see Figure 6.20).

Figure 6.19: Effect of Microalgae HTL surrogate blended fuels on peak pressure and

rate of pressure rise.


Figure 6.20: Effect of Microalgae HTL surrogate blended fuels on boost pressure.


In this section, engine exhaust emissions, including specific NOx, CO, PM and

PN, are discussed. The engine was operated at a maximum torque speed condition

(1500 rpm) with four different loads.

Gaseous emissions

Figure 6.21 and Figure 6.22 show NO2 and NOx emissions with respect to engine

load for the reference diesel and three surrogate blends. At low-load condition (25%),

the formation of NO2 emissions with surrogate blends was much higher than that at

high loads (50%, 75% and 100%), which could be due to pre-injection. This pre-

injection works through an engine management system (EMS) for low-load

conditions. Further research is therefore required to confirm the causes to higher NO2

emissions at low-load conditions. However, compared to the reference diesel, all

surrogate blends produced higher NOx emissions at all engine loads. Figure 6.24 shows

the percentage increase of NOx, which is approximately 15–20%, with respect to the

reference diesel. This is due to the oxygen percentage of surrogate blends, which is

consistent with the published literature [78, 81, 225]. Nabi et al. [220] reported that



higher NOx emissions resulted from fuel oxygen. The higher NOx emissions with

surrogate blends are associated with the higher maximum pressure rise rates (Figure

6.19) during the premixed combustion and lower CN, which is shown in Table 6.3. As

shown in Figure 6.21 and Figure 6.22, the percentage of normalised NO2 compared to

NOx is 4–5.5% for all tested fuels except for a 25% load of surrogate fuel.

Figure 6.21: Brake-specific nitrogen dioxide (NO2) emissions for four different load.


Figure 6.22: Brake-specific nitrogen oxide (NOx) emissions for four different loads.

Figure 6.23: Percentage increases of NOx emissions compared to reference diesel.

25 50 75 100

Load (% of full load)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5N

Ox (

g/k

Wh)

100D 90D10S 80D20S 50D50S

EURO-III



Figure 6.24: Brake-specific CO emissions for four different loads.

Figure 6.25: Percentage reduction of CO emissions compared to reference diesel.

The CO emission is one indication of the incomplete combustion of the air-fuel

mixture that takes part in the combustion chamber [226]. Diesel engines generally


produce low CO emissions as they usually run on a lean mixture [227]. It is important

to note that all surrogate blends reduced CO emissions compared to those of the

reference diesel at every loading condition. This can be seen in Figure 6.24. This is

due to the oxygen content of the fuel, which helps to complete combustion. [226]. A

maximum 45% reduction in CO emissions with surrogate blends was observed

compared to the reference diesel. Furthermore, the CO emissions among all fuels were

within the EURO IIIA standard limit (5 g/kWh) [82].

Particle emissions

Figure 6.26 illustrates particulate matter (PM) emissions using three surrogate

blends (90D10S, 80D20S and 50D50S) and the reference diesel (100D). Reductions

in PM emissions with microalgae HTL surrogate blends were obtained compared to

those with the reference diesel, which is shown Figure 6.27. Nabi et al. [220] and Zare

et al. [80] reported reduced PM emissions with oxygenated fuels. The literature has

revealed that the increases in surface tension improve fuel combustion, while reducing

NOx and PM emissions [82]. PM emissions are significantly affected by the fuelling

system, engine operating conditions and ambient conditions [223, 228]. However, the

relationship between PM and surface tension is not linear and surface tension is

possibly not the only factor to reduce PM emissions—there are other fuel properties

that could influence PM reductions [82]. The current investigations are consistent with

a number of previous studies [3, 5, 229]. It is interesting to note that the PM emissions

are significantly lower than the Euro IIIA standard for all tested fuels, which is shown

in Figure 6.27. Compared with the Euro IIIA standard, all three surrogate blends

showed remarkable reductions in PM emissions. Relative to the reference diesel, a

maximum of 88% PM reductions was observed with the surrogate blends.

Variations in the brake-specific PN emissions across the four different fuels at

four loading conditions are shown in Figure 6.28. For all loading conditions, surrogate

blends reduced PN emissions compared to those of the reference diesel (100D). At

medium- to high-load conditions, the reductions in PN emissions among the surrogate

blends were low compared with low-load conditions. The percentage reduction of PN

compared to the reference diesel is shown in Figure 6.29. The literature showed that

oxygenated fuels reduced PN emissions [5, 57, 230]. The current investigation

therefore supports the published literature [35, 38, 51].



Figure 6.26: Variation of brake-specific particulate mass for different loads.

Figure 6.27: Percentage of reduction of particulate mass emissions compared to

reference diesel.

25 50 75 100

Load (% of full load)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

PM

(g

/kW

h)

100D 90D10S 80D20S 50D50S

EURO-III


Figure 6.28: Variation of brake-specific PN for four different loads.

Figure 6.29: Percentage reduction of PN emissions compared to reference diesel.



Based on the results discussed above, it can be concluded that microalgae HTL

surrogate blends performed well in terms of engine performance and exhaust

emissions. Most of the emissions using microalgae HTL surrogate blends were

reduced due to the similarity in their physical and chemical properties with biocrude.

However, all engine performance parameters showed insignificant change with

microalgae HTL surrogate blends due to the similarities in energy content with that of

the reference diesel.


6.5 CONCLUSION

The objective of this study was to develop a microalgae surrogate using a pure

chemical compound of microalgae HTL biocrude that effectively approximated the

chemical composition, density, viscosity, HHV, and surface tension of the reference

diesel. Engine performance and exhaust emissions were also investigated with

microalgae surrogate blends in a six-cylinder fully-instrumented turbo-charged diesel

engine.

The aromatics, cyclic ketone, alkane, alcohol, and aromatic FAME chemical

groups were used to produce target surrogate fuel by HTL microalgae biocrude. Each

chemical compound of surrogate fuel had its physicochemical properties controlled by

the target fuel. The interaction between each chemical compound was already

quantified because those chemical compounds were part of the same microalgae

biocrude.

No significant changes in engine performance were observed with HTL

surrogate blends when compared to those of the reference diesel.

All major emissions, including PM, PN and CO, were reduced significantly with

the surrogate blends, with increasing in NOx emission.

When compared with the reference diesel, a maximum of approximately 88%

and 58% reductions in PM emissions were obtained with the surrogate blends at 25%

and 100% of full load. Maximum reductions in PN emissions with the surrogate blends

were found at lower loads, but minimum reductions were found at medium and higher

loads.

NOx emissions with surrogate blends were higher compared to those of the

reference diesel. Exhaust after treatment, including exhaust gas recirculation technique

or changing the injection timing, could also reduce NOx emissions with surrogate

blends and thus needs more investigation.




This research was supported by the Australian Research Council’s Linkage

Projects funding scheme (project number LP110200158). The authors would also like

to acknowledge Mr. Andrew Elder from DynoLog Dynamometer Pty Ltd and Mr. Noel

Hartnett for their laboratory assistance, Dr. Md Jahirul Islam and Dr. Svetlana

Stevanovic for their guidance, and Mohammad Jafari for assistance with measuring

instruments.

Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 123

Chapter 7: Investigation of diesel engine

performance and exhaust

emissions using tyre oil

Farhad M. Hossain1,2*, Thomas J. Rainey1,2, Timothy Bodisco3, Trevor Bayley4,

Denis Randall4, Zoran Ristovski1,2, Richard J. Brown1,2

1Biofuel Engine Research Facility, Queensland University of Technology (QUT), QLD 4000,

Australia 2School of Chemistry, Physics and Mechanical Engineering, QUT, QLD 4000 Australia 3School of Engineering, Deakin University, Waurn Ponds, Victoria 3217, Australia 4Green Distillation Technologies (GDT) Corporation Limited, Victoria 3142, Australia












Title and status: Investigation of diesel engine performance and exhaust emissions

using tyre oil (under review)




the results, wrote the manuscript and acted as the corresponding author.

Signature

Date



Professor Richard Brown is a mechanical engineer, he is a leading

expert in thermodynamics and environmental fluid mechanics,

particularly in relation to internal combustion engine performance and

emissions.

Aided the design of the experiment, conducted the experiments,

interpreted the results, discussed and edited the manuscript.

Thomas J. Rainey Dr Thomas Rainey has 15 years of industrial and research experience

in biomass processing particularly in pulp and paper and sugar

processing. His research focuses on bioenergy and related value-added

products.

Design concept of fuel properties measurements and edited the

manuscript as an associate supervisor.

Timothy Bodisco Dr Timothy Bodisco has been working as a Lecturer in the Department

of Mechanical Engineering at Deakin University. He has extensive

experience with engine experimental data analysis.

Dr Bodisco assisted with analyses of in-cylinder data using his own

matlab code and edited the manuscript.

Trevor Bayley Trevor Bayley has been working as a Chief Operating Officer (COO)

of GDT. Trevor Bayley and his company, Professor Richard Brown

and I have been working collaboratively.

Mr Bayley provided tyre oil for testing in the diesel engine.

Denis Randall Denis Randall is an inventor of GDT and is currently a GDT Technical

Director.

Zoran Ristovski Professor Zoran Ristovski is a physicist who works at Queensland



Professor Zoran Ristovski designed and performed fuel properties

related to engine exhaust emissions and reviewed the manuscript.



I have sighted email or other correspondence from all Co-authors confirming their certifying

authorship.


Name Signature Date


Abstract:

This study investigates diesel engine performance and exhaust emissions using

tyre oil as an alternative fuel. There are approximately 20 million tons of end-of-life

tyres (ELTs) in the world today. In a novel process, Green Distillation Technologies

Corportation Ltd (GDT) converts whole ELTs into carbon, steel, and tyre oil. The

physiochemical properties of the tyre oil are similar to diesel fuel and the fuel is

miscible with diesel in any blended ratio. An engine experiment was conducted on a

EURO IIIA diesel engine at the Biofuel Engine Research Facility (BERF) at

Queensland University of Technology (QUT). All experiments were performed at

constant speed and four different engine loads. Two blends (10% and 20%) of tyre oil

were compared to reference diesel fuel. Exhaust emissions, including gaseous

emissions, particulate matter (PM) and particle count (PN), were investigated. The

results found significant changes, NOx emissions were reduced by approximately 30%

for both the 10% and 20% tyre oil blends when compared to the reference diesel fuel.

Other exhaust emissions, including PM and PN, were reduced significantly by 35-60%

and 5-20%, respectively, for both tyre oil blends. The only exception was the result for

CO, which showed an increase of approximately 2–3% compared to the reference

diesel, although not at a 25% load. Small changes were found with the tyre oil blends

with respect to engine performance parameters, including brake power (BP), brake

mean effective pressure (BMEP) and brake thermal efficiency (BTE). The engine

remained compliant with its EURO IIIA certification during the use of the tyre oil

blends.

Keywords: Tyre oil, diesel engine, emissions, pyrolysis, destination.


7.1 INTRODUCTION

Exhaust emissions regulations are becoming increasingly strict, globally.

However, the maximum exhaust emissions level for each country varies despite the

emissions legislation [231]. Diesel engine exhaust emissions may be controlled in

three ways: through engine modification, exhaust gas after-treatments or by using

alternatives to diesel fuel [232]. Engine manufacturing industries and researchers are

actively seeking alternative fuels for diesel engines that can reduce exhaust emissions.

Researchers are also trying to uncover reliable and efficient alternative feedstocks for

renewable fuels, including biomass feedstocks: corn, jatropha [233], palm oil [234],

mahua [235] and lignocellusic biomass [236], and non-biomass feedstocks, such as:

municipal waste and end-of-life tyres (ELTs) [24, 133, 166]. Unfortunately, the

majority are not able to be produced on a large enough scale owing to high production

costs. Many are also unsuitable for use in current diesel engines due to their

physiochemical properties.

There is a growing problem concerning ELTs disposal, globally [24]. Most

people are aware that ELTs are a significant environmental hazard, but few know the

extent of the mass that is generated each year. It has been reported that each year over

1 billion ELTs are generated worldwide, a number expected to increase to 1.5 billion

(or 20 million tons) by 2020, which represents a significant problem in terms of waste

disposal [13, 24]. These ELTs sometimes finish up in dumps, either legally or

illegally. One such tyre dump in the US has many millions of tyres, while one in the

Middle East is so vast that it can be seen from space. It has been reported that

Australians generate over 23 million ELTs, or 51 million equivalent passenger units

(EPU), each year [25]. A site in Stawell, Victoria, Australia contains an estimated 10

million old tyres. Local media have stated that if it caught fire, the local township

would be uninhabitable for 35 years [18]. Therefore, ELTs to fuel technology offers a

very promising solution for both issues [24].

ELTs are an organic waste from which useful energy in the form of liquid, gas

or solid can be derived. The calorific value of rubber from tyres is 35-40 MJ/kg, so

vehicle tyres appear very promising as a feedstock for fuel production [24, 26].

Australian Green Distillation Technologies (GDT) has invented a technique to produce

an alternative to diesel fuel from ELTs [18]. The technology reduces the whole tyres

to their original constituents, which are carbon, steel, and tyre oil [18].


The literature shows that tyre pyrolysis oil (TPO) has a lower cetane number

(CN) compared to diesel fuel [160, 237]. Some tyre pyrolysis oils use a cetane

improver such as ethers, diethyl ether, nitrides, amines, in the blend for their engine

experimental research [138]. Vihar et al. [24] tested TPO with and without an

intercooler to investigate the effect of the intake air temperature in an engine

turbocharged. They found a significant change in exhaust emissions, including

nitrogen oxide (NOx), carbon monoxide (CO) and total hydrocarbon (THC) when

compared with reference diesel fuels. Tudu et al. [138, 166] tested TPO in a diesel

engine as a blend with diesel fuel. They found that increasing the percentage of TPO

in the blend decreased NOx, but the opposite result was found for CO emissions [138].

In this research the tyre oil properties were tested and analysed before engine

experiments were conducted at Queensland University of Technology (QUT). Many

properties of tyre oil were found to be similar to diesel fuel, particularly CN, higher-

heating value (HHV), and density. To the best of the authors’ knowledge, only a

limited number of experiments investigating the effect of TPO as an alternative fuel

have been performed on a common-rail multi-cylinder turbo-charged (TC) engine[18].

The objectives of this study were to comparatively investigate diesel engine

performance and exhaust emissions with tyre oil blends without any cetane improver

or engine modification. The significance of this research is to determine the thermal

efficiency and exhaust emissions of this new innovative tyre oil in a commercial diesel

engine and establish a non-conventional fuel application in a regular engine without

modification. The performance of the engine output is presented in terms of in-cylinder

pressure, brake power (BP), brake mean effective pressure (BMEP), brake thermal

efficiency (BTE) and brake-specific fuel consumption (BSFC). Gaseous emissions of

nitrogen dioxide (NO2), nitrogen oxide (NOx), carbon monoxide (CO), particulate

matter (PM) and particulate number (PN) were measured and compared among the

tested fuels.

7.2 FUEL PRODUCTION AND PREPARATION

The GDT process for ELTs produces tyre oil, carbon and steel. The process emits

minimal emissions because most gases released by tyre processing are re-treated and

burnt to supply process heat. Many conversion technologies have been developed to

convert various feedstocks into fuels. Thermochemical conversion processes involve


pyrolysis and hydrothermal liquefaction that have been used for transforming many

feedstocks into fuels [132]. Thermochemical conversion processes use high

temperatures with or without the presence of oxygen to cause structural degradation.

Such technology has drawn much interest because it can directly produce liquid fuels

[36]. The hydrothermal liquefaction process is mainly used to convert wet feedstocks

into liquid fuels [136]. On the other hand, the pyrolysis process uses dry feedstock as

the raw materials to convert to liquid fuels. There are two tyres of feedstocks based on

water contains, those are contained water called wet feedstocks and those are not

contained water or remove water from feedstocks called dry feedstocks. Pyrolysis

processes depend on factors such as temperature, material size, and time [68,

150].However, as far as the authors can ascertain, these processes are generally not

economically viable to produce fuel from ELTs.

GDT has achieved a technological breakthrough by successfully and

commercially recycling end-of-life car and truck/bus tyres into the valuable

commodities of oil, carbon, and steel. ELTs are a blight on the environment because

until now, no means have been found to effectively and profitably recycle them [18].

However, using a technique known as destructive distillation, GDT can turn this

wasted resource and environmental hazard into three high-demand valuable raw

materials: tyre oil, carbon, and steel. Table 7.1 shows the GDT-recycled product and

quantity based on tyre types. The process is emissions free and part of this tyre oil is

used as fuel for the burner which is a heat source for the production process.

Table 7.1: GDT recycled product and quantity based on tyre types [18].

Types of Tyre Unit

(mass)

Kg

Recycled product in weight

Tyre Oil (Kg) Carbon

(Kg)

Steel

(Kg)

Car tyre 10 3.5 – 4.0 3.5 – 4.0 1.5 – 2.0

Truck tyre 70 28.0 – 30.0 28 – 30.0 11.0 – 14.0

Giant mining tyre 7,000 2,800 – 3,000 2,800 – 3,000 1,000 -1,400


The experiments were conducted at QUT in the Biofuel Engine Research Facility

(BERF) using two different blends. Two blends were prepared using tyre oil: 10% and


20% by volume with diesel. The engine was operated at a consistent speed of 1500

rpm (maximum torque speed), at four different loads 25%, 50%, 75% and 100%.

Maximum load at any engine speed depends upon type of fuel used, therefore the

maximum load for each fuel was determined when the engine was 1500 rpm.

This study used a Cummins EURO IIIA common-rail six-cylinder, turbo-

charged and after-cooled diesel engine with the specifications shown in

Table 7.2. The engine has a capacity of

5.9 L, maximum torque of 820 Nm at 1500 rpm and maximum power of 162 kW at

2000 rpm. The engine can be operated with a dual fuel mode and was coupled with a

water-flow dynamometer for loading the engine at different loads and speeds. The

software electronically controls the dynamometer. Figure 7.1 shows the schematic of

the experimental engine setup.

Table 7.2: Test-engine specifications.

The set of fuels used in the experiments is shown in Table 7.3. The first row

represents the name of the four different fuels—100D, 100T, 90D10T, and

80D20T.Classified by the volume of each fuel. The important physicochemical

properties of the fuels were experimentally measured. The blend properties were

calculated based on pure fuel properties that are shown in Table 7.3 [3, 57]. The

properties of tyre oil were tested and were found to be similar to diesel fuel when

comparing HHV, viscosity, and density. Regarding elemental composition, carbon and

hydrogen contents for tyre oil compare well with those for diesel fuel, while the sulfur

contents for tyre oil remarkably high compare to diesel. However, before conducting

the experimental studies, a careful fuel analysis was carried out. It is broadly accepted

that fuel properties influence the fuel-spray characteristics, fuel evaporation, the

Model Cummins ISBe220 31

Cylinders 6 in-line

Capacity 5.9 L

Bore x stroke 102 x 120 (mm)

Maximum power 162 kW @ 2500 rpm

Maximum torque 820 Nm @ 1500 rpm

Compression ratio 17.3:1

Aspiration Turbocharged

Fuel injection High-pressure common rail

Dynamometer type Electronically-controlled water brake dynamometer

Emission standard Euro IIIA


formation of fuel droplet size, distribution of fuel atoms and, therefore, the exhaust

emissions. These features depend on the physiochemical properties of the fuel.

Figure 7.1 shows a schematic of the engine performance and exhaust emission

measurements. The engine operating data load, mass flow rate of fuel and air, and

speed, were logged using Dynalog software. Further details of the engine performance

measurements can be found in Bodisco and Brown [221]. Various instruments were

used for exhaust emission measurements including DMS500, DustTrack (Model

8530), SABLE (CA-10) and CAI 600. The Cambustion DMS500 is uniquely suited

for a variety of diesel particulate filter applications. CAI 600 series analysers were

used to measure raw exhaust gasses CO, CO2, NO and NOx, and Sable and DustTrack

used to measure diluted CO2 gas and particulate mass respectively. Further details of

the engine exhaust emission measurements can be found in Rahman et al. [57].

Table 7.3: Properties of diesel, tyre oil and their blends.

Properties Methods 100D 100T 90D10T 80D20T

Density(Kg/L)1,2 ASTM D4052 0.844 0.847 0.845 0.845

HHV(MJ/kg)1,2 ASTM D240 45.64 42.28 45.31 44.97

LHV(MJ/kg) -- 43.95 39.05 43.46 42.97

K. viscosity (mm2/s)1,2 ASTM D445 2.66 3.43 2.74 2.81

Lubricity (mm)1,2 IP 450 0.412 0.289 0.339 0.387

Carbon (% wt.)3 -- 87 84.1 86.71 86.42

Hydrogen (%wt.)3 -- 13 15.9 13.29 13.58

C:H3 -- 6.69 5.29 6.52 6.36

Sulfur (ppm) ASTM D7039 7.2 3500 356.46 705.76

Ash content (mg/kg)1,2 ASTM D482 0.01 0.001 0.0091 0.0082

Flashpoint (°C)1,2 ASTM D93 68.66 97 71.49 74.32

Cetane index1,2 ASTM D4737A 51.74 51.7 51.74 51.73

1- Caltex fuel certificate, 2- Tyre oil certificate, 3- Calculated


Compressed Air

SABLE CA-10Dust Track

Diesel Engine Exhaust emissions flow Diluted exhaust flow

CAI gas analyser

Engine control roomEngine room

DMS500

Figure 7.1: Schematic diagram of the engine exhaust measurement system used for

this study.


This section describes the engine performance and exhaust emissions using tyre

oil and blends of diesel and tyre oil, as well as a comparison of individual

measurements. The engine performance measurements include BP, IP, IMEP, BSFC,

ISFC, BTE, and ITE. In-cylinder pressure versus crank angle and volume are presented

in separate figures, for all tested fuels. The results with tyre oil blends were compared

to some other published results [5]. The research showed no significant difference in

the performance of the BP, BSFC and BTE parameters between the tyre oil blends and

the reference diesel tested in the same engine [220, 223]. However, the exhaust

emissions, including NO2, NOx, CO, PM and PN, were significantly different using

neat tyre oil when compared to other experimental results [24, 138, 166]. Ideally, the

results from both the diesel and the tyre oil blends engine performance and emissions

should be compared with those of tyre pyrolysis oil produced from other techniques

[24, 138].



The indicated power (IP) of an engine is the power produced in the cylinder.

Conversely, the BP is the useful power at the output shaft. The IP and BP variation

with engine load are shown in Figure 7.2. The difference between the IP and BP

reduced as load increased, indicating a reduction in power. This is consistent with the

findings of other researchers [5, 80, 218, 220, 238]. The maximum IP output at 100%

of full load for diesel was approximately 130 kW. There was no significant change

found in power between 100D, 90D10T and 80D20T fuels for either the diesel or

blends. This is most likely due to the relatively high calorific value of tyre oil, which

is approximately 42.8 MJ/kg and compares well with that of diesel (45.64 MJ/kg).

Figure 7.2: IP and BP variation with IMEP for three different fuels.

Figure 7.3 shows the BTE and BSFC, which are calculated using equations (7.1)

and (7.2), respectively. BTE can be defined as ratio of brake power to fuel power. BTE

is used to define how mechanically efficient the engine is at converting chemical

energy from the fuel to useful mechanical energy [5]. In this study, BTE reached its

maximum at around 0.95 MPa of IMEP for all fuels, which is about 38%. Zare et al.


[80] and Nabi et al. [223] conducted experiments with the same engine using waste

cooking oil and reported similar results. The BTE was almost constant after 1.1 MPa

of IMEP. There were no significant changes found between the diesel and their blends.

This may be due to the similarity between fuel properties including HHV, CN and

density of the fuel, which were shown in Table 7.3.

The BSFC is a measure of the fuel effectiveness of the engine. It is typically used

for comparing the efficiency of engines with output power. However, as shown in

Figure 7.3, there were a very small change (about 1-2%) in BSFC with respect to load

among the diesel and tyre oil blends. The BSFC for diesel and the blends ranged

between 217–225 g/kWh for all load conditions. As depicted in Figure 7.3, while BTE

decreased with increased IMEP, BSFC increased with increased IMEP for diesel and

their blends. A similar observation was made by Islam et al. [3] and Nabi et al. [5].

Therefore, it can be said that an inverse relationship was found between BTE and

BSFC.

𝐵𝑇𝐸 =𝐵𝑃∗100

Mf ∗ 𝐿𝐻𝑉 -------------------------------------------------- (7.1)

𝐵𝑆𝐹𝐶 =3600∗𝑀𝑓∗1000

BP ------------------------------------------------- (7.2)

Where, BTE in % and BSFC in g/kWh, BP in kW, Mf is the mass flow rate of fuel in

kg/s, and LHV is the lower heating value of fuel in MJ/kg.


Figure 7.3: BTE and BSFC variation with IMEP for three different fuels.

Figure 7.4: ITE and ISEC variation with IMEP for three different fuels.

The indicated thermal efficiency (ITE) and indicated specific fuel consumption

(ISFC) were calculated using equations (7.3) and (7.4). As Figure 7.4 shows, ITE had

almost the same variation for all tested fuels with load. The ITE reduced gradually


with increasing engine load for both blended fuels, which is consistent with published

results [224]. On the other hand, ISFC indicated that the fuel efficiency of the engine

was affected with respect to thrust output. Figure 7.4 also shows that ISFC slightly

increased with increasing engine load but was almost the same for both blends. It can

be concluded that there was no change in fuel efficiency when using tyre-oil blends,

compared to diesel fuels.

𝐼𝑇𝐸 =𝐼𝑃∗100

𝑀𝑓∗𝐿𝐻𝑉 ---------------------------------------- (7.3)

𝐼𝑆𝐹𝐶 =3600∗𝑀𝑓∗1000

IP ------------------------------------ (7.4)

The slope of the pressure versus crank-angle curve gives an approximate value

for the start of combustion [239]. Variation of in-cylinder pressure (P) with respect to

the crank angle (CA) for different fuels90D10T, 80D20T, and 100Dis shown in Figure

7.5 and Figure 7.6 for 100% and 50% loads respectively. To minimise the effect of

cycle-to-cycle variations, the in-cylinder pressure data were recorded for 750

consecutive cycles and a mean cycle determined to plot Figure 7.5. The maximum

pressure was found for reference diesel fuel among all tested fuels, which was

approximately 11 MPa whereas this is the minimum for 80D20T blends. The peak

pressure of the cylinder reduced gradually as the load decreased for all tested fuels.

Furthermore, there was a small reduction 3-5% in peak pressure corresponding to

crank angle for the diesel and tyre-oil blends. This may be due to the difference in

HHV between diesel and tyre oil. The amount of heat generated in the cylinder is

related to C: H ratio, which is almost the same for diesel and tyre-oil blends. The C:H

ratio for 100D, 90D10T and 80D20T are 6.69, 6.52 and 6.36, respectively. This C:H

ratio, HHV and CN may be the reason for a small variation pressure curve. However,

it was observed cylinder peak pressure decrease with increases blend ratios and as a

decrease in load reduced the differences in cylinder pressure.


Figure 7.5: Variation of cylinder pressure with crank angle at 100% load for three

different fuels.

Figure 7.6: Variation of cylinder pressure with crank angle at 50% load for three

different fuels.


The real engine cycle of a CI four-stroke engine can be presented by plotting the

pressure vs volume data extracted from in-cylinder pressure data. The in-cylinder

volume is a function of the crank angle so that it is possible to relate the cylinder

pressure to cylinder volume which constructs a PV diagram as shown in Figure 7.7 for

and Figure 7.8 for 100% and 50% of full load respectively. Further detail of the PV

curve can be found in appendix D. When the piston is at bottom dead center (BDC),

the cylinder will have its largest volume. As the piston moves up the cylinder, the

volume is reduced. At the top dead center (TDC) the cylinder is at its minimum

volume. From Figure 7.7 it can be seen that the peak pressure is consistently high for

diesel. This is due to the heat of combustion in the cylinder.


different fuels.



different fuels.

Peak cylinder pressure is the maximum in-cylinder pressure achieved during the

combustion process. The cylinder pressure is important because its relationship to

work. Figure 7.9 shows the peak pressure and rate of pressure rise of the cylinder

compared to the IMEP curve. There were no changes in peak pressure for different

fuels except at the maximum IMEP, for peak pressure. The rate of maximum pressure

rise was the same for the three different fuels in the same operating conditions. Figure

7.9 shows that the variation of maximum pressure rise curves was insignificant for all

tested loads except at a low IMEP. However, the rate of the rise in pressure was almost

the same for both tyre-oil blends. The only difference was with the reference diesel

fuel. The reason for the high level of maximum pressure rise for the tyre oil blend at

load are not clear at this stage. However, this may be important for interpreting NOx

emissions as it has normally been observed that increases in the maximum rate of

pressure rise are often associated with increases in NOx concentration, which has not

been found here. It may also have been caused by the physiochemical properties of


the tyre oil. This is an important avenue to investigate further in future. The highest

peak pressure was found at approximately 11000 kPa.

Figure 7.9: Effect of tyre oil on peak pressure.

7.4.2 Engine exhaust emissions

This section discusses engine exhaust emissions, including NOx, CO, PM and

PN, were measured and can be seen in the following Figures. The engine operated at

a constant RPM. Four loads tested with 100% corresponding to maximum torque (820

Nm) and reducing down to 25% load. All the emissions data were recorded at stable

and specific engine loads.

NOx emissions

The brake specific NOx formation in diesel engines is reportedly influenced by:

ignition delay, combustion temperature, compression ratio, CN and oxygen in the fuels

[5, 166, 240]. The variation of NO2 and NOx with load for the tested fuels are shown

in Figure 7.10 and Figure 7.11. It is also observed from both figures that about 5-10%

NO2 were produced compare to NOx. The two key factors predominantly affecting the

formation of the NOx emission in a diesel engine are the combustion temperature and

the ignition delay. At a constant power output, a maximum of 30% reduction in NOx


was found for GDT-tyre-oil blends, compared to diesel fuel. The parameters affecting

the formation of oxides of NOx in a diesel engine are the in-cylinder combustion

temperature, duration, higher compression ratio, engine operating speed,

physiochemical properties of fuel including CN, oxygen content etc. [13, 24, 138,

205]. There is no single explanation why NOx emissions change between fuels, rather

these emissions depend on a number of factors. However, in this case it is clear that

CN is not a factor in the observed NOx change since it is almost identical for both

diesel and tyre oil, (51.74 and 51.7, respectively).”

However, need further research to find out for that. Tudu et al. [166] reported

lower NOx emissions with increased tyre oil and diesel blends. It was reported by Frigo

et al. [237] that nitrogen oxide reduces as the volume percentage of the tyre pyrolysis

oil (TPO) rises in the mixture. The current investigation supports those similar studies

[80, 81, 138, 220]. The NOx results for all of all the tested fuels were lower when

compared to the EURO IIIA a standard 3.81 g/kWh.

CO emissions

The variation of CO with load for all tested fuels is shown in Figure 7.12. The

CO exhaust emissions are one indicator of incomplete combustion of the air-fuel

mixture that occurs in the combustion chamber [138, 237]. Diesel engines generally

produce low CO emissions as they run on a lean mixture. As shown in Figure 7.12,

there was no consistent increase or decrease of CO with the increase of engine load..

The maximum change of CO emissions was found at 25% load for both of the blended

fuels. Two important factors predominantly affect the formation of the CO in diesel

engine: incomplete combustion and air-fuel ratio. At low load operation condition this

may be due to a lean mixture at a low engine load operation.

The experimental results show that CO exhaust emissions change according to

the percentage of tyre-oil in the blends when compared to the reference diesel. Similar

results have also been reported in other published studies [145, 237, 241]. However,

the result for CO among all the tested fuels was within the EURO IIIA—a standard

limit of 5.0 g/kWh. CO emissions could be reduced using oxygenated fuel as an

additive with diesel and tyre-oil blends [220, 229].


Figure 7.10: Brake-specific NO2 emissions for four different loads.

Figure 7.11: Brake-specific NOx emissions for four different loads.


Figure 7.12: Brake-specific CO emissions for four different loads.

Particulate mass emissions

Figure 7.13 shows the results for particulate mass (PM) emitted by the engine

using the following fuels: 100D, 90D10T and 80D20T. There were significant

decreases in particulate mass emissions between the diesel and tyre-oil blends. The

CN number of tyre oil was 51.7, very similar to diesel. Increases in CN improve fuel

combustion, while reducing NOx and PM emissions. However, the relationship

between PM and CN is not linear and there are other properties, aside from CN, that

may influence PM. The results are consistent with a number of studies conducted

previously [3, 5, 229]. The PM reduction was more than 35% for both 10% and 20%

blends when compared to diesel. Finally, it was found that PM emissions for all the

tested fuels was low when compared to the EURO IIIA standard of 0.3.

NOx and PM have often been observed to have an inverse relationship. This is

generally most evident for a constant fuel operated in an engine with varying RPM and

loads. Comparisons of NOx and PM in Figures 11 and 13 did not show the above

simple trend most likely due to fuels of very different compositions (eg diesel and tyre

oil) increasing the complexity of the NOx – PM trade off mediated by cylinder


temperature, especially in the combustion zone. While the conventional NOx - PM has

been observed for comparisons of diesel and renewable fuels many researchers have

not observed that trend [34, 87, 116, 205, 242, 243].

Particulate number emissions

Variation of the brake specific PN with loads for different fuels is shown in

Figure 7.14. The maximum amount of PN was for the reference diesel fuel, which was

reduced in both 10% and 20% tyre oil blends. It can be seen from that the PN reduced

gradually according to the percentage of tyre oil in the blend. It can also be seen that

PN emissions were high at 25% of full load for each of the fuels. The percentage of

change of PN for blended fuel varied between 5-20% compared to diesel, which was

high at its low load condition. In this experiment, no oxygenated compounds were

used, so the results for PN are not influenced because of this. It was also observed that

the physical properties of tyre oil were similar to diesel, so it seems unlikely that PN

was influenced by this. The reduction of PN may be due to chemical properties of the

tyre oil such as chemical composition and structure. To the authors’ knowledge, the

measurement of PN with tyre oil is new and it is important to investigate further to

understand how PN changes with tyre oil.


Figure 7.13: Variation of brake-specific PM emissions for different loads.

Figure 7.14: Variation of brake-specific PN emissions for four different loads.


7.5 CONCLUSION

In this study, diesel engine performance and exhaust emissions were measured

with 10% and 20% (by volume) tyre oil blends. The properties of the tyre oil were

measured and compared with the reference diesel. There was a small change found in

engine performance using tyre oil blends when compared to diesel, which may be due

to the energy content of the blends. Conversely, the brake-specific exhaust emissions

of NO2, NOx, CO, PM, and PN were measured and significant changes were found.

The brake-specific NOx decreased by 30% with tyre oil blends compared to the

reference diesel fuel. However, brake-specific emissions of CO increased with the

amount of tyre oil blended. PM and PN also reduced within the experiment. The PM

reduced by more than one third for tyre oil blends compared to diesel fuel. Tyre oil

properties, especially CN, HHV and density, were almost the same as diesel and there

was no separation found in the blends, which may be the reason for these results. The

results are very encouraging for the future use of tyre oil a blended alternative fuel,

like 10% ethanol (E10) for diesel engines. E10 is used as an alternative for petrol

engine. However, tests including aging, reliability, and durability need to be conducted

first.



This research was supported by the Australian Department of Industry,

Innovation and Science funded project (project number ICG000077). The author

would like to acknowledge Dr. Md Mostafizur Rahman for assistance with reviewing

this manuscript and would like to special thanks to Noel Hartnett for his help to

conduct experiments. The author would like to extend my great thanks to Niki

Widdowson, and Dennis Rutzou for their help in the waste-tyre oil project.

Chapter 8: Conclusions and Recommendations 149

Chapter 8: Conclusions and

Recommendations

8.1 CONCLUSION

The research presented in this thesis aimed to investigate wet microalgae and

waste tyre as potential feedstock for alternative fuel using HTL and pyrolysis as a

thermochemical process. The particular focus with both fuels was on their

physicochemical properties and use in a CI engine. Microalgae HTL biocrude is not

suitable for use in a CI engine directly due to its physicochemical properties.

Consequently, a new surrogate fuel was developed based on the microalgae HTL

biocrude chemical compound and tested in a CI engine. Conversely, waste-tyre oil was

suitable for use directly as a blend in the engine test.

This project has filled a significant gap in the field of alternative fuel research,

including research into methods of reducing waste tyres from the environment. A

careful investigation of microalgae HTL surrogate and waste-tyre oil performance in

a CI engine and their emission characteristics have contributed significantly to the

existing literature.

8.1.1 Selection for feedstock

Feedstock selection is one of the most important steps to solve real-world

problems because the availability of the feedstock depends on large-scale production.

Microalgae have recently received a lot of attention in the production of biofuel as a

renewable feedstock because of their potential for mass production, having the

advantages of rapid growth, high-oil yield per unit area, and being cultivated on non-

arable land. Conversely, there is the growing problem of waste-tyre disposal globally.

Most people are aware that ELTs are a significant environmental hazard, but few know

the extent of the mass that is generated each year. It has been reported that each year

over one billion waste tyres are generated worldwide and this is expected to increase

to 1.5 billion by 2020, which is a huge problem in terms of waste disposal.


8.1.2 Thermochemical conversion

Thermochemical conversion is the use of heat, with or without the presence of

oxygen, to convert various feedstocks into other forms of energy. Among different

thermochemical conversion processes, pyrolysis and hydrothermal conversion are

most popular for their smooth operation. Microalgae can be solvent extracted to

recover lipids, which subsequently undergo a traditional transesterification reaction to

produce FAMEs—normally known as biodiesel. However, for microalgae, the raw

material should be dried (at considerable expense) prior to the solvent extraction. A

second method undergoing intensive research is HTL, which can utilise wet biomass

to produce a biocrude. HTL converts biomass into gas, liquid and solids similar to

pyrolysis, but operates at a higher pressure and at a lower temperature. Tyres are an

organic waste from which useful energy in the form of liquid, gas or solid can be

derived. Meanwhile, the calorific values of rubber from tyres is 35–40 MJ/kg, so

vehicle tyres appear a very promising source of feedstock for fuel production.

However, Australian company GDT has invented a technique to produce an alternative

to diesel fuel from waste-disposal tyres. The technology reduces the full tyres to their

original constituents, which are carbon, steel, and tyre oil.

8.1.3 Analysis of physicochemical properties of fuel

The physicochemical properties of alternative fuel are important parameters to

consider in respect to the quality of the fuel and its application. The physicochemical

properties vary with the difference in chemical composition such as carbon-chain

length and the degree of saturation/unsaturation. Physicochemical properties include:

chemical composition, number of bonds in the molecule, molecular structure, fuel

density, viscosity, surface tension, heating value, CN, acid value, sulphur contents and

so on. These are the main factors that determine whether the fuel can be used in a

conventional engine. Moreover, the fuel properties affect the engine performance and

emission results. A number of studies have shown that fuel properties cause changes in

engine-exhaust emissions. There is widespread agreement that no single factor is

responsible for biodiesel engine performance and exhaust emissions. In this study, the

physicochemical properties have been analysed and it has been shown that changes in

those properties along with changes in the experimental condition for some microalgae

feedstock affect engine performance and exhaust emissions (see Chapter 4). The

physicochemical properties exhibited by microalge HTL biocrude show significant


differences to microalgae FAME, conventional biofuel and diesel. The HTL results in

the breakdown of long-chain fatty acids, yielding shorter molecules and different

cyclic carbohydrates, giving higher yields. For microalgae, solvent extraction obtains

nonpolar storage lipids and membrane lipids along with some pigments. The variation

in the chemical composition, such as carbon-chain length and the degree of

saturation/unsaturation, changes the physicochemical properties of the biofuel.

Similarly, a careful analysis of waste-tyre oil was carried out and compared to diesel

fuel. The GDT-tyre oil is black and has a recognisable odour. The carbon residue

content is high compared to standard diesel fuel but if this is reduced it will help to

improve the fuel colour. The percentage of polycyclic aromatic HC and sulphur need

to be reduced so they fall within the range of regular diesel. At present, it is more

suitable for some off-road applications.

8.1.4 Diesel engine test

There is no literature available to validate the use of microalgae HTL biocrude

in diesel engine performance since its physiochemical properties make it unsuitable

for such use. Chapter 2 contains a detailed literature review of microalgae alternative

fuel. In this research, a new surrogate fuel was developed, which was suitable for a

diesel engine test. The experimental investigation of HTL microalgae surrogate fuel in

engine performance and emission characteristics is presented in Chapter 5. On the

other hand, information regarding the effect of waste-tyre oil on engine performance

and emission characteristics is extremely limited in the literature and even less

information is available in relation to turbo-charged diesel engines. Chapter 3

presented a detailed literature review on this topic.

In this study, it was found that HTL microalgae surrogate blended with diesel

(10%, 20% and 50%) in a turbo-charged common-rail diesel engine, generates almost

the same power as diesel alone. HTL microalgae surrogate blends have significant

variations when compared to petroleum diesel, especially in relation to gaseous

emissions. There is a significant increase in CO2, NO, and NOx emissions with all

blends when compared to petroleum diesel. However, the HC emissions reduce

significantly with microalgae-methyl-ester blends. After investigating all the

microalgae-methyl-ester blends, it was found that a 20% microalgae blend with

petroleum diesel showed the closest performance to petroleum diesel.


The GDT-tyre oil was blended with diesel at two different volume percentages

(10% and 20%). The properties of GDT-tyre oil were measured and compared with

regular diesel before the experiments were conducted. There was no change found in

engine performance using tyre-oil blends when compared to diesel. Conversely, the

brake-specific exhaust emissions of NO2, NOx, CO, PM, and PN, were measured and

a significant change was found. The brake-specific NOx decreased by approximately

30% for each load, with increased percentages of GDT-tyre oil in the blends.

Conversely, it was observed that brake-specific emissions of CO increased slightly

with GDT-tyre-oil-blended fuels. PM and PN also showed a decrease in the

experimental results. The PM reduced by more than one-third for GDT-tyre oil

compared to diesel fuel for each load. GDT-tyre oil properties, especially CN, HHV

and density, were almost the same as diesel. There was also separation found in the

blends, which may be the reason for such results. The results from GDT-tyre oil are

very encouraging for future use as an alternative fuel to diesel in CI engines. However,

tests including aging, reliability, and durability need to be conducted before these fuels

can be used in engines.

8.2 APPLICATION OF OUTCOMES

The outcomes of this research could be implemented in industry to produce

alternative fuels. Microalgae biocrude could be used directly in marine-diesel engines.

Considering the increasing number of waste tyres every year all over the world, this

waste removal problem could be solved by converting the tyre into fuel using GDT

technology.

8.3 LIMITATIONS

There are some limitations in this research, which are summarised below.

Enough biocrude cannot be produced due to limitations of feedstocks.

The waste-tyre oil tested up to 20% by volume.

The production cost of microalgae biofuel is expensive compared to

mineral diesel fuel.


8.4 RECOMMENDATIONS AND FUTURE STUDIES

There are several further studies that could be carried out to continue this

research. Regarding microalgae biofuel production, hybrid conversion techniques

could reduce production costs.

Two-stage biofuel production is a method that combines solvent-extracted lipids

into biofuel through a FAME-based process and biocrude by the HTL method. This is

a hybrid conversion method, as shown in Figure 8.1. The microalgae biomass is

converted into biofuel and the biomass waste, after solvent extraction, is used to

produce biocrude through the HTL process. The waste that comes from HTL is then

used as a fertiliser. At the same time, the heat produced from the HTL reactor is used

to produce steam, which can be used to produce electric power. The products are a

CO2-rich gas and water with nutrients that can be used to grow microalgae. This

proposed technique should reduce the per unit biofuel cost and simultaneously help to

recycle all waste produced through the conversion process.

Dry

microalgae

Solvent

extractor

Transesteri-

ficationBiodiesel

Biomass after

lipid extraction

Hydrothermal

liquefactionBio-crude

Solid residule

CO2 rich gas

Water and nutrients recycle

Fertilizer

Heat recovery

Hot water Cold water

Electricity

generationMicroalgae

Fuel pump

Figure 8.1: Microalgae hybrid conversion process.

A current challenge for researchers is the production cost of microalgae biofuel, which

is still expensive compared to mineral diesel fuel. It is possible to reduce the

microalgae biofuel production cost with hybrid production. However, the literature

Solvent extraction

HTL


shows that most of the cost comes from the cultivation of microalgae, which is about

20–30% of the total cost [87, 244]. It has been estimated that the microalgae biomass

production cost per kilogram is $2.95 and $3.80 for photobioreactors and raceways,

respectively. The microalgae production cost would be reduced to approximately

$0.47 and $0.60 per kilogram for photobioreactors and raceways respectively if the

production capacity increased to 10,000 tons per year. Considering microalgae

biomass is 30% oil by weight, then the cost of the biomass for providing a litre of oil

would be approximately $1.40 and $1.81 for photobioreactors and raceways,

respectively [87, 245]. This is still expensive compared to normal diesel fuel.

However, the microalgae biofuel production cost would be reduced further using the

proposed hybrid conversion technology. For microalgae biofuel to be competitive with

diesel, the algal oil price should be less than $1/L and this may be possible using a

hybrid technology.


Bibliography

[1] Cremonez PA, Feroldi M, Feiden A, Gustavo Teleken J, José Gris D, Dieter J,

et al. Current scenario and prospects of use of liquid biofuels in South America.

Renewable and Sustainable Energy Reviews 2015;43:352-62.

[2] Azad AK, Rasul MG, Khan MMK, Sharma SC, Hazrat MA. Prospect of

biofuels as an alternative transport fuel in Australia. Renewable and

Sustainable Energy Reviews 2015;43:331-51.

[3] Islam MA, Rahman MM, Heimann K, Nabi MN, Ristovski ZD, Dowell A, et

al. Combustion analysis of microalgae methyl ester in a common rail direct

injection diesel engine. Fuel 2015;143:351-60.

[4] Islam MA, Brown RJ, O’Hara I, Kent M, Heimann K. Effect of temperature

and moisture on high pressure lipid/oil extraction from microalgae. Energy

Conversion and Management 2014;88(0):307-16.

[5] Nabi MN, Rahman MM, Islam MA, Hossain FM, Brooks P, Rowlands WN, et

al. Fuel characterisation, engine performance, combustion and exhaust

emissions with a new renewable Licella biofuel. Energy Conversion and

Management 2015;96:588-98.

[6] Jahirul M, Koh W, Brown R, Senadeera W, Hara I, Moghaddam L. Biodiesel

Production from Non-Edible Beauty Leaf (Calophyllum inophyllum) Oil:

Process Optimization Using Response Surface Methodology (RSM). Energies

2014;7(8):5317.

[7] Jahirul MI, Brown RJ, Senadeera W, Ashwath N, Rasul MG, Rahman MM, et

al. Physio-chemical assessment of beauty leaf (Calophyllum inophyllum) as

second-generation biodiesel feedstock. Energy Reports 2015;1:204-15.

[8] Rahman M, Rasul M, Hassan N. Study on the Tribological Characteristics of

Australian Native First Generation and Second Generation Biodiesel Fuel.

Energies 2017;10(1):55.

[9] Grima EM, González MJI, Giménez AG. Solvent Extraction for Microalgae

Lipids. In: Borowitzka MA, Moheimani NR, editors. Algae for Biofuels and

Energy. Dordrecht: Springer Netherlands; 2013, p. 187-205.

[10] Islam M, Magnusson M, Brown R, Ayoko G, Nabi M, Heimann K. Microalgal

Species Selection for Biodiesel Production Based on Fuel Properties Derived

from Fatty Acid Profiles. Energies 2013;6(11):5676-702.

[11] Chiaramonti D, Prussi M, Buffi M, Rizzo AM, Pari L. Review and

experimental study on pyrolysis and hydrothermal liquefaction of microalgae

for biofuel production. Applied Energy 2017;185, Part 2:963-72.

[12] Williams PT. Pyrolysis of waste tyres: A review. Waste Management

2013;33(8):1714-28.

[13] İlkılıç C, Aydın H. Fuel production from waste vehicle tires by catalytic

pyrolysis and its application in a diesel engine. Fuel Processing Technology

2011;92(5):1129-35.

[14] Martínez JD, Murillo R, García T, Veses A. Demonstration of the waste tire

pyrolysis process on pilot scale in a continuous auger reactor. Journal of

Hazardous Materials 2013;261:637-45.

[15] de Marco Rodriguez I, Laresgoiti MF, Cabrero MA, Torres A, Chomón MJ,

Caballero B. Pyrolysis of scrap tyres. Fuel Processing Technology

2001;72(1):9-22.

Bibliography 157

[16] Islam MR, Joardder MUH, Hasan SM, Takai K, Haniu H. Feasibility study for

thermal treatment of solid tire wastes in Bangladesh by using pyrolysis

technology. Waste Management 2011;31(9–10):2142-9.

[17] Laresgoiti MF, Caballero BM, de Marco I, Torres A, Cabrero MA, Chomón

MJ. Characterization of the liquid products obtained in tyre pyrolysis. Journal

of Analytical and Applied Pyrolysis 2004;71(2):917-34.

[18] GDT. Green distillation technologies corporation Ltd http://wwwgdtc6com/

25/08/2016.

[19] Davis R, Aden A, Pienkos PT. Techno-economic analysis of autotrophic

microalgae for fuel production. Applied Energy 2011;88(10):3524-31.

[20] Razon LF, Tan RR. Net energy analysis of the production of biodiesel and

biogas from the microalgae: Haematococcus pluvialis and Nannochloropsis.

Applied Energy 2011;88(10):3507-14.

[21] Darzins A, Pienkos P, L. E. Current status and potential for algal biofuels

production, a report to IEA Bioenergy Task 39. . IEA Bioenergy 2010. Report

T39-T2. .

[22] Doshi A, Pascoe S, Coglan L, Rainey T. The financial feasibility of microalgae

biodiesel in an integrated, multi-output production system. . Submitted 2017.

[23] Raheem A, Wan Azlina WAKG, Taufiq Yap YH, Danquah MK, Harun R.

Thermochemical conversion of microalgal biomass for biofuel production.


[24] Vihar R, Seljak T, Rodman Oprešnik S, Katrašnik T. Combustion

characteristics of tire pyrolysis oil in turbo charged compression ignition

engine. Fuel 2015;150:226-35.

[25] TSA. Tyre Stewardship Australia http://wwwtyrestewardshiporgau 2017.

[26] Martínez JD, Rodríguez-Fernández J, Sánchez-Valdepeñas J, Murillo R,

García T. Performance and emissions of an automotive diesel engine using a

tire pyrolysis liquid blend. Fuel 2014;115:490-9.

[27] BREE. Australian Bureau of Resource and Energy Economics wwwbreegovau

2013.

[28] FGE. Facts global energy wwwfgenergycom 2013.

[29] Yilmaz N, Vigil FM, Burl Donaldson A, Darabseh T. Investigation of CI

engine emissions in biodiesel–ethanol–diesel blends as a function of ethanol

concentration. Fuel 2014;115:790-3.

[30] Bodisco T, Reeves R, Situ R, Brown R. Bayesian models for the determination

of resonant frequencies in a DI diesel engine. Mechanical Systems and Signal

Processing 2012;26:305-14.

[31] Nabi MN, Brown RJ, Ristovski Z, Hustad JE. A comparative study of the

number and mass of fine particles emitted with diesel fuel and marine gas oil

(MGO). Atmospheric Environment 2012;57:22-8.

[32] Eboibi BE-O, Lewis DM, Ashman PJ, Chinnasamy S. Hydrothermal

liquefaction of microalgae for biocrude production: Improving the biocrude

properties with vacuum distillation. Bioresource Technology 2014;174:212-

21.

[33] Díaz-Vázquez LM, Rojas-Pérez A, Fuentes-Caraballo M, Robles-Ramos IV,

Jena U, Das KC. Demineralization of Sargassum spp. macroalgae biomass:

selective hydrothermal liquefaction process for bio-oil production. Frontiers in

Energy Research 2015;3.

http://wwwgdtc6com/

http://wwwtyrestewardshiporgau/


[34] Wahlen BD, Morgan MR, McCurdy AT, Willis RM, Morgan MD, Dye DJ, et

al. Biodiesel from Microalgae, Yeast, and Bacteria: Engine Performance and

Exhaust Emissions. Energy & Fuels 2013;27(1):220-8.

[35] Mata TM, Martins AA, Caetano NS. Microalgae for biodiesel production and

other applications: A review. Renewable and Sustainable Energy Reviews

2010;14(1):217-32.

[36] Elliott DC, Hart TR, Neuenschwander GG, Rotness LJ, Roesijadi G, Zacher

AH, et al. Hydrothermal processing of macroalgal feedstocks in continuous-

flow reactors. ACS Sustainable Chemistry & Engineering 2014;2:07-215.

[37] Kanda H, Li P, Ikehara T, Yasumoto-Hirose M. Lipids extracted from several

species of natural blue–green microalgae by dimethyl ether: Extraction yield

and properties. Fuel 2012;95:88-92.

[38] Chen Y-H, Huang B-Y, Chiang T-H, Tang T-C. Fuel properties of microalgae

(Chlorella protothecoides) oil biodiesel and its blends with petroleum diesel.

Fuel 2012;94:270-3.

[39] Wisniewski Jr A, Wiggers VR, Simionatto EL, Meier HF, Barros AAC,

Madureira LAS. Biofuels from waste fish oil pyrolysis: Chemical composition.

Fuel 2010;89(3):563-8.

[40] Hussain J, Ruan Z, Nascimento IA, Liu Y, Liao W. Lipid profiling and

corresponding biodiesel quality of Mortierella isabellina using different drying

and extraction methods. Bioresource Technology 2014;169:768-72.

[41] Dandı̇k L, Aksoy HA. Effect of catalyst on the pyrolysis of used oil carried out

in a fractionating pyrolysis reactor. Renewable Energy 1999;16(1–4):1007-10.

[42] Adebanjo AO, Dalai AK, Bakhshi NN. Production of Diesel-Like Fuel and

Other Value-Added Chemicals from Pyrolysis of Animal Fat. Energy & Fuels

2005;19(4):1735-41.

[43] Hedayat F, Stevanovic S, Milic A, Miljevic B, Nabi MN, Zare A, et al.

Influence of oxygen content of the certain types of biodiesels on particulate

oxidative potential Science of the Total Environment 2016;546:381-8.

[44] Surawski NC, Miljevic B, Roberts BA, Modini RL, Situ R, Brown RJ, et al.

Particle Emissions, Volatility, and Toxicity from an Ethanol Fumigated

Compression Ignition Engine. Environmental Science & Technology

2009;44(1):229-35.

[45] Barrios CC, Martín C, Domínguez-Sáez A, Álvarez P, Pujadas M, Casanova J.

Effects of the addition of oxygenated fuels as additives on combustion

characteristics and particle number and size distribution emissions of a TDI

diesel engine. Fuel 2014;132:93-100.

[46] Nabi MN, Minami M, Ogawa H, Miyamoto N. Ultra low emission and high

performance diesel combustion with highly oxygenated fuel. SAE Tech Pap

Ser; 2000, 2000-01-0231 2000.

[47] Eboibi BE, Lewis DM, Ashman PJ, Chinnasamy S. Effect of operating

conditions on yield and quality of biocrude during hydrothermal liquefaction

of halophytic microalga Tetraselmis sp. Bioresource Technology 2014;170:20-

9.

[48] Tommaso G, Chen W-T, Li P, Schideman L, Zhang Y. Chemical

characterization and anaerobic biodegradability of hydrothermal liquefaction

aqueous products from mixed-culture wastewater algae. Bioresource

Technology 2015;178:139-46.

Bibliography 159

[49] Jena U, Das KC, Kastner JR. Effect of operating conditions of thermochemical

liquefaction on biocrude production from Spirulina platensis. Bioresource

Technology 2011;102(10):6221-9.

[50] Zhou D, Zhang L, Zhang S, Fu H, Chen J. Hydrothermal Liquefaction of

Macroalgae Enteromorpha prolifera to Bio-oil. Energy & Fuels

2010;24(7):4054-61.

[51] Xu Y-P, Duan P-G, Wang F. Hydrothermal processing of macroalgae for

producing crude bio-oil. Fuel Processing Technology 2015;130:268-74.

[52] Xu C, Lad N. Production of Heavy Oils with High Caloric Values by Direct

Liquefaction of Woody Biomass in Sub/Near-critical Water. Energy & Fuels

2008;22(1):635-42.

[53] Elliott DC, Hart TR, Neuenschwander GG, Rotness LJ, Roesijadi G, Zacher

AH, et al. Hydrothermal processing of macroalgal feedstocks in continuous-

flow reactors,. ACS Sustain Chem Eng 2 2014;07–215.

[54] López Barreiro D, Prins W, Ronsse F, Brilman W. Hydrothermal liquefaction

(HTL) of microalgae for biofuel production: State of the art review and future

prospects. Biomass and Bioenergy 2013;53:113-27.

[55] Dote Y, Sawayama S, Inoue S, Minowa T, Yokoyama S-y. Recovery of liquid

fuel from hydrocarbon-rich microalgae by thermochemical liquefaction. Fuel

1994;73(12):1855-7.

[56] Sawayama S, Minowa T, Yokoyama SY. Possibility of renewable energy

production and CO2 mitigation by thermochemical liquefaction of microalgae.

Biomass and Bioenergy 1999;17(1):33-9.

[57] Rahman MM, Pourkhesalian AM, Jahirul MI, Stevanovic S, Pham PX, Wang

H, et al. Particle emissions from biodiesels with different physical properties

and chemical composition. Fuel 2014;134:201-8.

[58] Hasanuzzamana M, Hossain FM, Rahim NA. Palm Oil EFB: green energy

source in Malaysia. Applied Mechanics and Materials 2014;619:376-80.

[59] Patil V, Tran KQ, Giselrod HR. Toward sustainable production of biofuels

from microalgae. Int J Mol Sci 2008;9:1188–95.

[60] Amin S. Review on biofuel oil and gas production processes from microalgae.

Energy Conversion and Management 2009;50(7):1834-40.

[61] Sambusiti C, Bellucci M, Zabaniotou A, Beneduce L, Monlau F. Algae as

promising feedstocks for fermentative biohydrogen production according to a

biorefinery approach: A comprehensive review. Renewable and Sustainable

Energy Reviews 2015;44:20-36.

[62] Medina AR, Grima EM, Giménez AG, Gonzalez M. Downstream processing

of algal polyunsaturated fatty acids. Biotechnology Advances 1998;16(3):517-

80.

[63] Demirbaş A. Production of biodiesel from algae oils. Energy Sources part A

2009;31:163–8.

[64] Dutta R, Sarkar U, Mukherjee A. Extraction of oil from Crotalaria Juncea seeds

in a modified Soxhlet apparatus: Physical and chemical characterization of a

prospective bio-fuel. Fuel 2014;116(0):794-802.

[65] Jahirul MI, Brown RJ, Senadeera W, Ashwath N, Rasul M, Rahman MM, et

al. Physio-chemical assessment of beauty leaf (Calophyllum inophyllum) as

second-generation biodiesel feedstock. Energy Reports 2015;1:204-15.

[66] Pragya N, Pandey KK, Sahoo PK. A review on harvesting, oil extraction and

biofuels production technologies from microalgae. Renewable and Sustainable

Energy Reviews 2013;24(0):159-71.


[67] Brennan L, Owende P. Biofuels from microalgae—A review of technologies

for production, processing, and extractions of biofuels and co-products.

Renewable and Sustainable Energy Reviews 2010;14(2):557-77.

[68] Srirangan K, Akawi L, Moo-Young M, Chou CP. Towards sustainable

production of clean energy carriers from biomass resources. Applied Energy

2012;100:172-86.

[69] Zhang L, Xu C, Champagne P. Overview of recent advances in thermo-

chemical conversion of biomass. Energy Conversion and Management

2010;51(5):969-82.

[70] Faeth JL, Valdez PJ, Savage PE. Fast Hydrothermal Liquefaction of

Nannochloropsis sp. To Produce Biocrude. Energy & Fuels 2013;27(3):1391-

8.

[71] Xiaowei P, Xiaoqian M, Yousheng L, Xusheng W, Xiaoshen Z, Cheng Y.

Effect of process parameters on solvolysis liquefaction of Chlorella

pyrenoidosa in ethanol–water system and energy evaluation. Energy

Conversion and Management 2016;117:43-63.

[72] Anastasakis K, Ross AB. Hydrothermal liquefaction of the brown macro-alga

Laminaria Saccharina: Effect of reaction conditions on product distribution and

composition. Bioresource Technology 2011;102(7):4876-83.

[73] Giakoumis EG. A statistical investigation of biodiesel physical and chemical

properties, and their correlation with the degree of unsaturation. Renewable

Energy 2013;50:858-78.

[74] Varatharajan K, Cheralathan M. Influence of fuel properties and composition

on NOx emissions from biodiesel powered diesel engines: A review.

Renewable and Sustainable Energy Reviews 2012;16(6):3702-10.

[75] Pandey RK, Rehman A, Sarviya RM. Impact of alternative fuel properties on

fuel spray behavior and atomization. Renewable and Sustainable Energy

Reviews 2012;16(3):1762-78.

[76] Kegl B. Effects of biodiesel on emissions of a bus diesel engine. Bioresource

Technology 2008;99(4):863-73.

[77] Vajda B, Lešnik L, Bombek G, Biluš I, Žunič Z, Škerget L, et al. The numerical

simulation of biofuels spray. Fuel 2015;144:71-9.

[78] Rakopoulos CD, Dimaratos AM, Giakoumis EG, Rakopoulos DC.

Investigating the emissions during acceleration of a turbocharged diesel engine

operating with bio-diesel or n-butanol diesel fuel blends. Energy

2010;35(12):5173-84.

[79] Kim D, Kim S, Oh S, No S-Y. Engine performance and emission

characteristics of hydrotreated vegetable oil in light duty diesel engines. Fuel

2014;125:36-43.

[80] Zare A, Nabi MN, Bodisco TA, Hossain FM, Rahman M, Ristovski ZD, et al.

The effect of triacetin as a fuel additive to waste cooking biodiesel on engine

performance and exhaust emissions. Fuel 2016;182:640-9.

[81] Nabi MN. Theoretical investigation of engine thermal efficiency, adiabatic

flame temperature, NOx emission and combustion-related parameters for

different oxygenated fuels. Applied Thermal Engineering 2010;30(8–9):839-

44.

[82] DieselNet. What Are Diesel Emissions.

https://wwwdieselnetcom/(21/05/2015) 2015.

https://wwwdieselnetcom/(21/05/2015

Bibliography 161

[83] McCormick R, Graboski M, Alleman T, Herring A, Tyson S. Impact of

biodiesel source material and chemical structure on emissions of criteria

pollutants from a heavy-duty engine. Environ Sci Technol 2001;35:1742–7.

[84] Song H, Tompkins BT, Bittle JA, Jacobs TJ. Comparisons of NO emissions

and soot concentrations from biodiesel-fuelled diesel engine. Fuel

2012;96:446-53.

[85] Agarwal AK. Biofuels (alcohols and biodiesel) applications as fuels for

internal combustion engines. Progress in Energy and Combustion Science

2007;33(3):233-71.

[86] Tüccar G, Özgür T, Aydın K. Effect of diesel–microalgae biodiesel–butanol

blends on performance and emissions of diesel engine. Fuel 2014;132:47-52.

[87] Tüccar G, Aydın K. Evaluation of methyl ester of microalgae oil as fuel in a

diesel engine. Fuel 2013;112:203-7.

[88] Kosinkova J, Ramirez JA, Nguyen J, Ristovski Z, Brown R, Lin C, et al.

Hydrothermal liquefaction of bagasse using ethanol and black liquor as

solvents. Biofuels, Bioproducts and Biorefining 2015;9(6):630-8.

[89] Ross AB, Biller P, Kubacki ML, Li H, Lea-Langton A, Jones JM.

Hydrothermal processing of microalgae using alkali and organic acids. Fuel

2010;89(9):2234-43.

[90] Torri C, Garcia Alba L, Samorì C, Fabbri D, Brilman DWF. Hydrothermal

Treatment (HTT) of Microalgae: Detailed Molecular Characterization of HTT

Oil in View of HTT Mechanism Elucidation. Energy & Fuels 2012;26(1):658-

71.

[91] Minowa T, Yokoyama S-y, Kishimoto M, Okakura T. Oil production from

algal cells of Dunaliella tertiolecta by direct thermochemical liquefaction. Fuel

1995;74(12):1735-8.

[92] Hossain FH, Kosinkova J, Brown RJ, Ristovski R, Stephens E, Hankamer B,

et al. Chemical-physical properties of a HTL biocrude from a high growth-rate

microalga at a larger laboratory scale. Energy and Fuels (Submitted on

September, 2016) 2016.

[93] Li D, Chen L, Xu D, Zhang X, Ye N, Chen F, et al. Preparation and

characteristics of bio-oil from the marine brown alga Sargassum patens C.

Agardh. Bioresource Technology 2012;104:737-42.

[94] Duan P, Bai X, Xu Y, Zhang A, Wang F, Zhang L, et al. Catalytic upgrading

of crude algal oil using platinum/gamma alumina in supercritical water. Fuel

2013;109:225-33.

[95] Duan P, Chang Z, Xu Y, Bai X, Wang F, Zhang L. Hydrothermal processing

of duckweed: Effect of reaction conditions on product distribution and

composition. Bioresource Technology 2013;135:710-9.

[96] Reda AA, Schnelle-Kreis J, Orasche J, Abbaszade G, Lintelmann J, Arteaga-

Salas JM, et al. Gas phase carbonyl compounds in ship emissions: Differences

between diesel fuel and heavy fuel oil operation. Atmospheric Environment

2014;94:467-78.

[97] Zheng Z, Tang X, Asa-Awuku A, Jung HS. Characterization of a method for

aerosol generation from heavy fuel oil (HFO) as an alternative to emissions

from ship diesel engines. Journal of Aerosol Science 2010;41(12):1143-51.

[98] Wan Ghazali WNM, Mamat R, Masjuki HH, Najafi G. Effects of biodiesel

from different feedstocks on engine performance and emissions: A review.



[99] Pham PX, Bodisco TA, Stevanovic S, Rahman MD, Wang H, Ristovski ZD, et

al. Engine Performance Characteristics for Biodiesels of Different Degrees of

Saturation and Carbon Chain Lengths. SAE Int J Fuels Lubr 2013;6(1):188-98.

[100] Choi CY, Reitz RD. An experimental study on the effects of oxygenated fuel

blends and multiple injection strategies on DI diesel engine emissions. Fuel

1999;78(11):1303-17.

[101] Utlu Z, Koçak MS. The effect of biodiesel fuel obtained from waste frying oil

on direct injection diesel engine performance and exhaust emissions.

Renewable Energy 2008;33(8):1936-41.

[102] Hansen A, Gratton M, Yuan W. Diesel engine performance and NOx emissions

from oxygenated biofuels and blends with diesel fuel. ASABE

2006;49(3):589-95.

[103] Öner C, Altun Ş. Biodiesel production from inedible animal tallow and an

experimental investigation of its use as alternative fuel in a direct injection

diesel engine. Applied Energy 2009;86(10):2114-20.

[104] Aydin H, Bayindir H. Performance and emission analysis of cottonseed oil

methyl ester in a diesel engine. Renewable Energy 2010;35(3):588-92.

[105] Ramadhas AS, Muraleedharan C, Jayaraj S. Performance and emission

evaluation of a diesel engine fueled with methyl esters of rubber seed oil.

Renewable Energy 2005;30(12):1789-800.

[106] Buyukkaya E. Effects of biodiesel on a DI diesel engine performance, emission

and combustion characteristics. Fuel 2010;89(10):3099-105.

[107] Kaplan C, Arslan R, Sürmen A. Performance Characteristics of Sunflower

Methyl Esters as Biodiesel. Energy Sources, Part A: Recovery, Utilization, and

Environmental Effects 2006;28(8):751-5.

[108] Lin L, Cunshan Z, Vittayapadung S, Xiangqian S, Mingdong D. Opportunities

and challenges for biodiesel fuel. Applied Energy 2011;88(4):1020-31.

[109] Demirbas A. Progress and recent trends in biofuels. Progress in Energy and

Combustion Science 2007;33(1):1-18.

[110] Surawski NC, Ristovski ZD, Brown RJ, Situ R. Gaseous and particle emissions

from an ethanol fumigated compression ignition engine. Energy Conversion

and Management 2012;54(1):145-51.

[111] Lapuerta M, Armas O, Rodríguez-Fernández J. Effect of biodiesel fuels on

diesel engine emissions. Progress in Energy and Combustion Science

2008;34(2):198-223.

[112] Sarvi A, Lyyränen J, Jokiniemi J, Zevenhoven R. Particulate emissions from

large-scale medium-speed diesel engines: 2. Chemical composition. Fuel

Processing Technology 2011;92(10):2116-22.

[113] Gautam A, Agarwal AK. Experimental Investigations of Comparative

Performance, Emission and Combustion Characteristics of a Cottonseed

Biodiesel-Fueled Four-Stroke Locomotive Diesel Engine. International

Journal of Engine Research 2012;0(0):1-19.

[114] Ghadikolaei MA. Effect of alcohol blend and fumigation on regulated and

unregulated emissions of IC engines—A review. Renewable and Sustainable

Energy Reviews 2016;57:1440-95.

[115] Mat Yasin MH, Yusaf T, Mamat R, Fitri Yusop A. Characterization of a diesel

engine operating with a small proportion of methanol as a fuel additive in

biodiesel blend. Applied Energy 2014;114:865-73.

Bibliography 163

[116] Islam MA. Microalgae: an alternative source of biodiesel for the compression

ignition (CI) engine. Queensland University of Technology 2014;PhD

thesis:38.

[117] Makarevičienė V, Lebedevas S, Rapalis P, Gumbyte M, Skorupskaite V,

Žaglinskis J. Performance and emission characteristics of diesel fuel

containing microalgae oil methyl esters. Fuel 2014;120:233-9.

[118] Fisher BC, Marchese AJ, Volckens J, Lee T, Collett JL. Measurement of

gaseous and particulate emissions from algae-based fatty acid methyl esters.

SAE International Journal of Fuels and Lubricants 2010;3(2):292-321.

[119] Merico E, Donateo A, Gambaro A, Cesari D, Gregoris E, Barbaro E, et al.

Influence of in-port ships emissions to gaseous atmospheric pollutants and to

particulate matter of different sizes in a Mediterranean harbour in Italy.

Atmospheric Environment 2016;139:1-10.

[120] Diab F, Lan H, Ali S. Novel comparison study between the hybrid renewable

energy systems on land and on ship. Renewable and Sustainable Energy

Reviews 2016;63:452-63.

[121] Kasper A, Aufdenblatten S, Forss A, Mohr M, Burtscher H. Particulate

emissions from a low-speed marine diesel engine. Aerosol Science and

Technology 2007;41:24–32.

[122] Goldsworthy L, Goldsworthy B. Modelling of ship engine exhaust emissions

in ports and extensive coastal waters based on terrestrial AIS data – An

Australian case study. Environmental Modelling & Software 2015;63:45-60.

[123] Wang S, Meng Q, Liu Z. Bunker consumption optimization methods in

shipping: A critical review and extensions. Transportation Research Part E:

Logistics and Transportation Review 2013;53:49-62.

[124] Johnson GR, Juwono AM, Friend AJ, Cheung H-C, Stelcer E, Cohen D, et al.

Relating urban airborne particle concentrations to shipping using carbon based

elemental emission ratios. Atmospheric Environment 2014;95:525-36.

[125] Burgard DA, Bria CRM. Bridge-based sensing of NOx and SO2 emissions

from ocean-going ships. Atmospheric Environment 2016;136:54-60.

[126] Khan MY, Agrawal H, Ranganathan S, Welch WA, Miller JW, Cocker DR.

Greenhouse Gas and Criteria Emission Benefits through Reduction of Vessel

Speed at Sea. Environmental Science & Technology 2012;46(22):12600-7.

[127] Williams EJ, Lerner BM, Murphy PC, Herndon SC, Zahniser MS. Emissions

of NOx, SO2, CO, and HCHO from commercial marine shipping during Texas

Air Quality Study (TexAQS) 2006. Journal of Geophysical Research:

Atmospheres 2009;114(D21306):1-14.

[128] Murphy SM, Agrawal H, Sorooshian A, Padró LT, Gates H, Hersey S, et al.

Comprehensive Simultaneous Shipboard and Airborne Characterization of

Exhaust from a Modern Container Ship at Sea. Environmental Science &

Technology 2009;43(13):4626-40.

[129] Agrawal H, Malloy QGJ, Welch WA, Wayne Miller J, Cocker Iii DR. In-use

gaseous and particulate matter emissions from a modern ocean going container

vessel. Atmospheric Environment 2008;42(21):5504-10.

[130] Chen G, Huey LG, Trainer M, Nicks D, Corbett J, Ryerson T, et al. An

investigation of the chemistry of ship emission plumes during ITCT 2002.

Journal of Geophysical Research: Atmospheres 2005;110(D10):1-15.

[131] Sinha P, Hobbs PV, Yokelson RJ, Christian TJ, Kirchstetter TW, Bruintjes R.

Emissions of trace gases and particles from two ships in the southern Atlantic

Ocean. Atmospheric Environment 2003;37(15):2139-48.


[132] Aydın H, İlkılıç C. Optimization of fuel production from waste vehicle tires by

pyrolysis and resembling to diesel fuel by various desulfurization methods.

Fuel 2012;102:605-12.

[133] Martínez JD, Puy N, Murillo R, García T, Navarro MV, Mastral AM. Waste

tyre pyrolysis – A review. Renewable and Sustainable Energy Reviews

2013;23:179-213.

[134] ETRMA. European tyre and rubber industry statistics. European tyre and

rubber manufacturing association http://wwwetrmaorg 2014.

[135] Sienkiewicz M, Kucinska-Lipka J, Janik H, Balas A. Progress in used tyres

management in the European Union: A review. Waste Management

2012;32(10):1742-51.

[136] Quek A, Balasubramanian R. Liquefaction of waste tires by pyrolysis for oil

and chemicals—A review. Journal of Analytical and Applied Pyrolysis

2013;101:1-16.

[137] Alguacil FJ, López Gómez FA, Ramos G. The recycling of end-of-life tyres.

Technological review. Revista de Metalurgia 2011;47:273-84.

[138] Tudu K, Murugan S, Patel SK. Effect of diethyl ether in a DI diesel engine run

on a tyre derived fuel-diesel blend. Journal of the Energy Institute

2016;89(4):525-35.

[139] Sharma A, Murugan S. Potential for using a tyre pyrolysis oil-biodiesel blend

in a diesel engine at different compression ratios. Energy Conversion and

Management 2015;93:289-97.

[140] Torretta V, Rada EC, Ragazzi M, Trulli E, Istrate IA, Cioca LI. Treatment and

disposal of tyres: Two EU approaches. A review. Waste Management

2015;45:152-60.

[141] Pehlken A, Müller DH. Using information of the separation process of

recycling scrap tires for process modelling. Resources, Conservation and

Recycling 2009;54(2):140-8.

[142] Bridgewater AV. Thermal conversion of biomass and waste. Bio-Energy

Research Group Aston University, Birmingham (UK) 2001.

[143] Bridgewater A. V. Peacocke G.V.C. Fast pyrolysis processes for biomass.

Renew Sustain Energy 2000:1-73.

[144] Zhang L, Zhou B, Duan P, Wang F, Xu Y. Hydrothermal conversion of scrap

tire to liquid fuel. Chemical Engineering Journal 2016;285:157-63.

[145] Doğan O, Çelik MB, Özdalyan B. The effect of tire derived fuel/diesel fuel

blends utilization on diesel engine performance and emissions. Fuel

2012;95:340-6.

[146] Panwar NL, Kothari R, Tyagi VV. Thermo chemical conversion of biomass –

Eco friendly energy routes. Renewable and Sustainable Energy Reviews

2012;16(4):1801-16.

[147] White JE, Catall WJ, Legendre BL. Biomass pyrolysis kinetics: a comparative

critical review with relevant agricultural residue case studies Anal Appl Pyrol

2011.

[148] Balat M, Balat M, Kırtay E, Balat H. Main routes for the thermo-conversion of

biomass into fuels and chemicals. Part 1: Pyrolysis systems. Energy

Conversion and Management 2009;50(12):3147-57.

[149] Ceylan R, Bredenberg JBs. Hydrogenolysis and hydrocracking of the carbon-

oxygen bond. 2. Thermal cleavage of the carbon-oxygen bond in guaiacol. Fuel

1982;61(4):377-82.

http://wwwetrmaorg/

Bibliography 165

[150] Sergio Canzana Capareda. Biomass Energy Conversion. Texas A&M

University,USA (wwwintechopencom) 2013.

[151] Miranda M, Pinto F, Gulyurtlu I, Cabrita I. Pyrolysis of rubber tyre wastes: a

kinetic study. Fuel 2013;103:542-52.

[152] Banar M, Akyıldız V, Özkan A, Çokaygil Z, Onay Ö. Characterization of

pyrolytic oil obtained from pyrolysis of TDF (Tire Derived Fuel). Energy


[153] Islam MR, Joardder MUH, Kader M, Sarker M. Valorization of solid tire

wastes available in Bangladesh by thermal treatment. 2011.

[154] Aylón E, Fernández-Colino A, Murillo R, Navarro M, García T, Mastral A.

Valorisation of waste tyre by pyrolysis in a moving bed reactor. Waste

management 2010;30(7):1220-4.

[155] Zhang Y, Williams PT. Carbon nanotubes and hydrogen production from the

pyrolysis catalysis or catalytic-steam reforming of waste tyres. Journal of

Analytical and Applied Pyrolysis 2016;122:490-501.

[156] Song Z, Yang Y, Zhao X, Sun J, Wang W, Mao Y, et al. Microwave pyrolysis

of tire powders: Evolution of yields and composition of products. Journal of

Analytical and Applied Pyrolysis 2017;123:152-9.

[157] Luo S, Feng Y. The production of fuel oil and combustible gas by catalytic

pyrolysis of waste tire using waste heat of blast-furnace slag. Energy


[158] TC. Thermal cracking. wwwhnqingzhicom/solution/140html 2017.

[159] Murugan S, Ramaswamy MC, Nagarajan G. The use of tyre pyrolysis oil in

diesel engines. Waste Management 2008;28(12):2743-9.

[160] Hariharan S, Murugan S, Nagarajan G. Effect of diethyl ether on Tyre pyrolysis

oil fueled diesel engine. Fuel 2013;104:109-15.

[161] Conesa JA, Martín-Gullón I, Font R, Jauhiainen J. Complete Study of the

Pyrolysis and Gasification of Scrap Tires in a Pilot Plant Reactor.

Environmental Science & Technology 2004;38(11):3189-94.

[162] Li SQ, Yao Q, Chi Y, Yan JH, Cen KF. Pilot-scale pyrolysis of scrap tires in a

continuous rotary kiln reactor. Industrial and Engineering Chemistry Research

2004;43(17):5133-45.

[163] Galvagno S, Casu S, Casabianca T, Calabrese A, Cornacchia G. Pyrolysis

process for the treatment of scrap tyres: Preliminary experimental results.

Waste Management 2002;22(8):917-23.

[164] Olazar M, Aguado R, Arabiourrutia M, Lopez G, Barona A, Bilbao J. Catalyst

effect on the composition of tire pyrolysis products. Energy and Fuels

2008;22(5):2909-16.

[165] Aylón E, Murillo R, Fernández-Colino A, Aranda A, García T, Callén MS, et

al. Emissions from the combustion of gas-phase products at tyre pyrolysis.

Journal of Analytical and Applied Pyrolysis 2007;79(1–2):210-4.

[166] Tudu K, Murugan S, Patel SK. Effect of tyre derived oil-diesel blend on the

combustion and emissions characteristics in a compression ignition engine

with internal jet piston geometry. Fuel 2016;184:89-99.

[167] Oncel SS. Microalgae for a macroenergy world. Renewable and Sustainable

Energy Reviews 2013;26(0):241-64.

[168] d’Ippolito G, Sardo A, Paris D, Vella FM, Adelfi MG, Botte P, et al. Potential

of lipid metabolism in marine diatoms for biofuel production. Biotechnology

for Biofuels 2015;8(1):1-10.


[169] Kosinkova J, Doshi A, Maire J, Ristovski Z, Brown R, Rainey TJ. Measuring

the regional availability of biomass for biofuels and the potential for

microalgae. Renewable and Sustainable Energy Reviews 2015;49:1271-85.

[170] Subramanian S, Barry AN, Pieris S, Sayre RT. Comparative energetics and

kinetics of autotrophic lipid and starch metabolism in chlorophytic microalgae:

implications for biomass and biofuel production. Biotechnology for Biofuels

2013;6(1):1-12.

[171] Guccione A, Biondi N, Sampietro G, Rodolfi L, Bassi N, Tredici MR.

Chlorella for protein and biofuels: from strain selection to outdoor cultivation

in a Green Wall Panel photobioreactor. Biotechnology for Biofuels

2014;7(1):1-12.

[172] Naveena B, Armshaw P, Tony Pembroke J. Ultrasonic intensification as a tool

for enhanced microbial biofuel yields. Biotechnology for Biofuels 2015;8(1):1-

13.

[173] Bennion EP, Ginosar DM, Moses J, Agblevor F, Quinn JC. Lifecycle

assessment of microalgae to biofuel: Comparison of thermochemical

processing pathways. Applied Energy 2015(0).

[174] Amin S. Review on biofuel oil and gas production processes from microalgae.

Energy Conversion and Management 2009;50(7):1834-40.

[175] Vardon DR, Sharma BK, Blazina GV, Rajagopalan K, Strathmann TJ.

Thermochemical conversion of raw and defatted algal biomass via

hydrothermal liquefaction and slow pyrolysis. Bioresource Technology

2012;109:178-87.

[176] Mandal S, Mallick N. Microalga Scenedesmus obliquus as a potential source

for biodiesel production. Applied Microbiology and Biotechnology

2009;84(2):281-91.

[177] Demirbas A. Progress and recent trends in biodiesel fuels. Energy Conversion

and Management 2009;50(1):14-34.

[178] Barreiro DL, Prins W, Ronsse F, Brilman W. Hydrothermal liquefaction (HTL)

of microalgae for biofuel production: state of the art review and future

prospects. Biomass and Bioenergy 2013;53:113-27.

[179] Xu D, Savage PE. Characterization of biocrudes recovered with and without

solvent after hydrothermal liquefaction of algae. Algal Research 2014;6, Part

A:1-7.

[180] Ramirez JA, Brown RJ, Rainey TJ. A Review of Hydrothermal Liquefaction

Bio-Crude Properties and Prospects for Upgrading to Transportation Fuels.

Energies 2015;8(7):6765-94.

[181] Biller P, Riley R, Ross A. Catalytic hydrothermal processing of microalgae:

decomposition and upgrading of lipids. Bioresource technology

2011;102(7):4841-8.

[182] Biller P, Ross A. Potential yields and properties of oil from the hydrothermal

liquefaction of microalgae with different biochemical content. Bioresource

Technology 2011;102(1):215-25.

[183] Brown TM, Duan P, Savage PE. Hydrothermal Liquefaction and Gasification

of Nannochloropsis sp. Energy & Fuels 2010;24(6):3639-46.

[184] Matsui T-o, Nishihara A, Ueda C, Ohtsuki M, Ikenaga N-o, Suzuki T.

Liquefaction of micro-algae with iron catalyst. Fuel 1997;76(11):1043-8.

[185] Valdez PJ, Dickinson JG, Savage PE. Characterization of product fractions

from hydrothermal liquefaction of Nannochloropsis sp. and the influence of

solvents. Energy & Fuels 2011;25(7):3235-43.

Bibliography 167

[186] Jakob G, Wolf J, Bui TV, Posten C, Kruse O, Stephens E, et al. Surveying a

Diverse Pool of Microalgae as a Bioresource for Future Biotechnological

Applications. J Phylogenetics Evol Biol 2013;4(153).

[187] Demirbas A. Calculation of Higher Heating Values of Biomass Fuels. Fuel

1997;76(431-434).

[188] Friedl A, Padouvas E, Rotter H, Varmuza K. Prediction of heating values of

biomass fuel from elemental composition. Analytica Chimica Acta

2005;544(1):191-8.

[189] Yu G, Zhang Y, Schideman L, Funk TL, Wang Z. Hydrothermal liquefaction

of low lipid content microalgae into bio-crude oil. American Society of

Agricultural Engineers 2011;54(1):239-46.

[190] Boie W. Fuel Technology Calculations. Energietechnik 3 1953:309-16.

[191] Xu C, Etcheverry T. Hydro-liquefaction of woody biomass in sub-and super-

critical ethanol with iron-based catalysts. Fuel 2008;87(3):335-45.

[192] Garcia Alba L, Torri C, Samorì C, van der Spek J, Fabbri D, Kersten SR, et al.

Hydrothermal treatment (HTT) of microalgae: evaluation of the process as

conversion method in an algae biorefinery concept. Energy & fuels

2011;26(1):642-57.

[193] Huang H, Yuan X, Zeng G, Wang J, Li H, Zhou C, et al. Thermochemical

liquefaction characteristics of microalgae in sub-and supercritical ethanol. Fuel

Processing Technology 2011;92(1):147-53.

[194] Toor SS, Rosendahl L, Rudolf A. Hydrothermal liquefaction of biomass: A

review of subcritical water technologies. Energy 2011;36(5):2328-42.

[195] Peterson AA, Vogel F, Lachance RP, Fröling M, Antal Jr MJ, Tester JW.

Thermochemical biofuel production in hydrothermal media: a review of sub-

and supercritical water technologies. Energy & Environmental Science

2008;1(1):32-65.

[196] Tyson KS, McCormick RL. Biodiesel handling and use guidelines.

Collingdale, United States: DIANE Publishing; 2006.

[197] Boelhouwer J, Nederbragt G, Verberg G. Viscosity data of organic liquids.

Applied Scientific Research 1951;2(1):249-68.

[198] Lang X, Dalai AK, Bakhshi NN, Reaney MJ, Hertz P. Preparation and

characterization of bio-diesels from various bio-oils. Bioresource technology

2001;80(1):53-62.

[199] Abramzon B, Sazhin S. Convective vaporization of a fuel droplet with thermal

radiation absorption. Fuel 2006;85(1):32-46.

[200] Vardon DR. Hydrothermal liquefaction for energy recovery from high-

moisture waste biomass. Master thesis, University of Illinois at Urbana

Champaign 2012:73.

[201] Elliott DC, Hart TR, Schmidt AJ, Neuenschwander GG, Rotness LJ, Olarte

MV, et al. Process development for hydrothermal liquefaction of algae

feedstocks in a continuous-flow reactor. Algal Research 2013;2(4):445-54.

[202] Situ R, Brown RJ, Ristovski Z, Kruger U, Hargreaves D. Analysis of Dual Fuel

Compression Ignition (Diesel) Engine. The Seventh International Conference

on Modeling and Diagnostics for Advanced Engine Systems 2008.

[203] Mofijur M, Masjuki H, Kalam M, Atabani A, Arbab M, Cheng S, et al.

Properties and use of Moringa oleifera biodiesel and diesel fuel blends in a

multi-cylinder diesel engine. Energy Conversion and Management

2014;82:169-76.


[204] Pawar M, Kadam A, Yemul O, Thamke V, Kodam K. Biodegradable bioepoxy

resins based on epoxidized natural oil (cottonseed & algae) cured with

citric and tartaric acids through solution polymerization: A renewable

approach. Industrial Crops and Products 2016;89:434-47.

[205] Hossain FM, Rainey TJ, Ristovski Z, Brown RJ. Performance and exhaust

emissions of diesel engines using microalgae FAME and the prospects for

microalgae HTL biocrude. Renewable and Sustainable Energy Reviews

Available online 16 June 2017.

[206] Sari YW, Bruins ME, Sanders JPM. Enzyme assisted protein extraction from

rapeseed, soybean, and microalgae meals. Industrial Crops and Products

2013;43:78-83.

[207] Chen Y, Mu R, Yang M, Fang L, Wu Y, Wu K, et al. Catalytic hydrothermal

liquefaction for bio-oil production over CNTs supported metal catalysts.

Chemical Engineering Science 2017;161:299-307.

[208] Pitz WJ, Mueller CJ. Recent progress in the development of diesel surrogate

fuels. Progress in Energy and Combustion Science 2011;37(3):330-50.

[209] Mueller CJ, Cannella WJ, Bruno TJ, Bunting B, Dettman HD, Franz JA, et al.

Methodology for Formulating Diesel Surrogate Fuels with Accurate

Compositional, Ignition-Quality, and Volatility Characteristics. Energy &

Fuels 2012;26(6):3284-303.

[210] Liu X, Wang H, Wang X, Zheng Z, Yao M. Experimental and modelling

investigations of the diesel surrogate fuels in direct injection compression

ignition combustion. Applied Energy 2017;189:187-200.

[211] Wu S, Yang H, Hu J, Shen D, Zhang H, Xiao R. The miscibility of

hydrogenated bio-oil with diesel and its applicability test in diesel engine: A

surrogate (ethylene glycol) study. Fuel Processing Technology 2017;161:162-

8.

[212] Das DD, McEnally CS, Kwan TA, Zimmerman JB, Cannella WJ, Mueller CJ,

et al. Sooting tendencies of diesel fuels, jet fuels, and their surrogates in

diffusion flames. Fuel 2017;197:445-58.

[213] Dooley S, Won SH, Chaos M, Heyne J, Ju Y, Dryer FL, et al. A jet fuel

surrogate formulated by real fuel properties. Combustion and Flame

2010;157(12):2333-9.

[214] Abboud J, Schobing J, Legros G, Bonnety J, Tschamber V, Brillard A, et al.

Impacts of oxygenated compounds concentration on sooting propensities and

soot oxidative reactivity: Application to Diesel and Biodiesel surrogates. Fuel

2017;193:241-53.

[215] Hossain FM, Kosinkova J, Brown RJ, Ristovski Z, Hankamer B, Stephens E,

et al. Experimental Investigations of Physical and Chemical Properties for

Microalgae HTL Bio-Crude Using a Large Batch Reactor. Energies

2017;10(4):467.

[216] Collins CD. Implementing Phytoremediation of Petroleum Hydrocarbons. In:

Willey N, editor Phytoremediation: Methods and Reviews. Totowa, NJ:

Humana Press; 2007, p. 99-108.

[217] Babaie M, Davari P, Zare F, Rahman MM, Rahimzadeh H, Ristovski Z, et al.

Effect of Pulsed Power on Particle Matter in Diesel Engine Exhaust Using a

DBD Plasma Reactor. IEEE Transactions on Plasma Science 2013;41(8):2349-

58.

Bibliography 169

[218] Zare A, Bodisco TA, Nabi MN, Hossain FM, Rahman MM, Ristovski ZD, et

al. The influence of oxygenated fuels on transient and steady-state engine

emissions. Energy 2017;121:841-53.

[219] Prasad R, Bella VR. A Review on Diesel Soot Emission, its Effect and Control

Bulletin of Chemical Reaction Engineering & Catalysis 2010;5(2):69-86.

[220] Nabi MN, Zare A, Hossain FM, Rahman MM, Bodisco TA, Ristovski ZD, et

al. Influence of fuel-borne oxygen on European Stationary Cycle: Diesel

engine performance and emissions with a special emphasis on particulate and

NO emissions. Energy Conversion and Management 2016;127:187-98.

[221] Bodisco T, Brown RJ. Inter-cycle variability of in-cylinder pressure parameters

in an ethanol fumigated common rail diesel engine. Energy 2013;52:55-65.

[222] NREL. Compendium of experimental cetane numbers. National Renewable

Energy Laboratory 2004.

[223] Nabi N, Zare A, Hossain M, Rahman MM, Stuart D, Ristovski Z, et al.

Formulation of new oxygenated fuels and their influence on engine

performance and exhaust emissions. Proceedings of the 2015 Australian

Combustion Symposium. The Combustion Institute Australia and New Zealand

Section; 2015:64-7.

[224] P. SK, Gopal P, Aravind S. Performance analysis of diesel engine with diesel,

ethanol & vegetable oil blends International Journal of Chemical Sciences

2015;13(2):576-84.

[225] Rashed MM, Kalam MA, Masjuki HH, Habibullah M, Imdadul HK, Shahin

MM, et al. Improving oxidation stability and NOX reduction of biodiesel

blends using aromatic and synthetic antioxidant in a light duty diesel engine.

Industrial Crops and Products 2016;89:273-84.

[226] Tan YH, Abdullah MO, Nolasco-Hipolito C, Zauzi NSA, Abdullah GW.

Engine performance and emissions characteristics of a diesel engine fueled

with diesel-biodiesel-bioethanol emulsions. Energy Conversion and

Management 2017;132:54-64.

[227] Hernández JJ, Lapuerta M, Barba J. Separate effect of H2, CH4 and CO on

diesel engine performance and emissions under partial diesel fuel replacement.

Fuel 2016;165:173-84.

[228] Giakoumis EG, Rakopoulos CD, Dimaratos AM, Rakopoulos DC. Exhaust

emissions with ethanol or n-butanol diesel fuel blends during transient

operation: A review. Renewable and Sustainable Energy Reviews

2013;17:170-90.

[229] Hossain F, Nabi M, Rahman M, Zare A, Rainey T, Stuart D, et al. Experimental

investigation of the effects of oxygenated fuels on exhaust emissions in a heavy

duty diesel engine. Australian Combustion Symposium ,7-9 December,

University of Melbourne, Vic 2015:56-9.

[230] Xue J, Grift TE, Hansen AC. Effect of biodiesel on engine performances and

emissions. Renewable and Sustainable Energy Reviews 2011;15(2):1098-116.

[231] E J, Pham M, Zhao D, Deng Y, Le D, Zuo W, et al. Effect of different

technologies on combustion and emissions of the diesel engine fueled with

biodiesel: A review. Renewable and Sustainable Energy Reviews

2017;80:620-47.

[232] Kalargaris I, Tian G, Gu S. Combustion, performance and emission analysis of

a DI diesel engine using plastic pyrolysis oil. Fuel Processing Technology

2017;157:108-15.


[233] Imtenan S, Masjuki HH, Varman M, Kalam MA, Arbab MI, Sajjad H, et al.

Impact of oxygenated additives to palm and jatropha biodiesel blends in the

context of performance and emissions characteristics of a light-duty diesel

engine. Energy Conversion and Management 2014;83:149-58.

[234] Ali OM, Mamat R, Abdullah NR, Abdullah AA. Analysis of blended fuel

properties and engine performance with palm biodiesel–diesel blended fuel.

Renewable Energy 2016;86:59-67.

[235] Aalam CS, Saravanan CG. Effects of nano metal oxide blended Mahua

biodiesel on CRDI diesel engine. Ain Shams Engineering Journal.

[236] Zabed H, Sahu JN, Boyce AN, Faruq G. Fuel ethanol production from

lignocellulosic biomass: An overview on feedstocks and technological

approaches. Renewable and Sustainable Energy Reviews 2016;66:751-74.

[237] Frigo S, Seggiani M, Puccini M, Vitolo S. Liquid fuel production from waste

tyre pyrolysis and its utilisation in a Diesel engine. Fuel 2014;116:399-408.

[238] Zare A, Bodisco T, Nabi N, Hossain M, Rahman MM, Stuart D, et al. Impact

of Triacetin as an oxygenated fuel additive to waste cooking biodiesel:

transient engine performance and exhaust emissions. Proceedings of the 2015

Australian Combustion Symposium. The Combustion Institute Australia and

New Zealand Section; 2015:48-51.

[239] Heywood JB. International Combustion Engine Fundamentals. McGraw-Hill,

Inc.

[240] Brunt MFJ, Platts KC. Calculation of Heat Release in Direct Injection Diesel

Engines. SAE International; 1999.

[241] Murugan S, Ramaswamy MC, Nagarajan G. Performance, emission and

combustion studies of a DI diesel engine using Distilled Tyre pyrolysis oil-

diesel blends. Fuel Processing Technology 2008;89(2):152-9.

[242] Nabi MN, Zare A, Hossain FM, Ristovski ZD, Brown RJ. Reductions in diesel

emissions including PM and PN emissions with diesel-biodiesel blends.

Journal of Cleaner Production 2017;166(Supplement C):860-8.

[243] Nabi MN, Zare A, Hossain FM, Ristovski ZD, Brown RJ. Reductions in diesel

emissions including PM and PN emissions with diesel-biodiesel blends.

Journal of Cleaner Production 2017.

[244] Demirbas A, Fatih Demirbas M. Importance of algae oil as a source of

biodiesel. Energy Conversion and Management 2011;52(1):163-70.

[245] Chisti Y. Biodiesel from microalgae. Biotechnology Advances

2007;25(3):294-306.

[246] Cambustion. DMS500 Fast Particle Analyzer.

http://wwwcambustioncom/products/dms500(2015/01/29).

[247] TSI. DustTrak II Aerosol Monitor 8530. http://wwwtsicom/dusttrak-ii-aerosol-

monitor-8530/(2015/01/29).

[248] Sayble. CA-10 Carbon Dioxide Analyzer. http://sablesyscom/products/classic-

line/ca-10-carbon-dioxide-analyzer/(2015/01/29).

http://wwwcambustioncom/products/dms500(2015/01/29

http://wwwtsicom/dusttrak-ii-aerosol-monitor-8530/(2015/01/29

http://wwwtsicom/dusttrak-ii-aerosol-monitor-8530/(2015/01/29

http://sablesyscom/products/classic-line/ca-10-carbon-dioxide-analyzer/(2015/01/29

http://sablesyscom/products/classic-line/ca-10-carbon-dioxide-analyzer/(2015/01/29

Appendices

171

Appendices

Appendix Contents

A MICROALGAE HTL BIOCRUDE PRODUCTION

B FUEL CERTIFICATE

C DIESEL ENGINE PERFORMANCE WITH SURROGATE BLENDS

D DIESEL ENGINE PERFORMANCE WITH TYRE OIL

E BIOFUEL ENGINE RESEARCH FACILITY (BERF) AT QUT


APPENDIX A: MICROALGAE HTL BIOCRUDE PRODUCTION

Hydrothermal liquefaction (HTL) was carried out using a high pressure and

temperature Parr reactor, which is shown in Figure A-1. HTL converts biomass into

liquid fuels and it is generally carried out at 250–450 °C in 1.8 L volume. The retention

time in the reactor is usually 5–120 min. HTL results in the breakdown of long-chain

fatty acids to shorter molecules, and carbohydrates are converted to straight carbon

chains, giving high yields. The gaseous products were vented. The liquid bio-crude

products were separated from the liquefied raw product using solvent extraction to

simplify the chemical analyses.

Figure A-1: Thermal liquefaction Parr reactor (High Pressure and Temperature).

Appendices

173

APPENDIX B: FUEL CERTIFICATE

Appendices

175

APPENDIX C: DIESEL ENGINE PERFORMANCE WITH SURROGATE

BLENDS

Appendix C is supplementary to Chapter 6. Further detail of the P-CA, PV and

emissions curve can be found in Chapter 6.

Figure C-1: Variation of cylinder pressure with crank angle for 75% load for

different fuels.



different fuels.


different fuels.

Appendices

177


different fuels.

Figure C-5: Variation of BMEP with engine load for different fuels.


Figure C-6: Variation of NO with engine load for different fuels.

Appendices

179

APPENDIX D: DIESEL ENGINE PERFORMANCE TYRE-OIL BLENDS

Appendix D is supplementary to Chapter 7. Further detail of the P-CA, PV and

emissions curve can be found in Chapter 7.

Figure D-1: Variation of cylinder pressure with crank angle for 75% load for

different fuels.



different fuels.


different fuels.

Appendices

181


different fuels.

Figure D-5: Variation of NO with engine load for different fuels.


APPENDIX E: BIOFUEL ENGINE RESEARCH FACILITY (BERF) AT QUT

Engine performance measurements:

Typically, diesel engine performance parameters refer to engine power, torque,

brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), indicated

pressure and brake mean effective pressure (BMEP). The engine’s operating data was

collected from the engine control unit (ECU) and in-cylinder pressure of cylinder one

data was collected using a pressure transducer.

Figure E-1: Six-cylinder turbo-charge EURO-III diesel engine.

Exhaust Emission measurements:

Different instruments—the DMS500, DustTrak and Sayble—were used to

measure particle number and mass, as well as other emissions. The gaseous emissions

such as CO, CO2, NO, NO2 and HC were also measured using laboratory-grade

equipment.

Appendices

183

DMS500. The Cambustion DMS500 is uniquely suited for a variety of diesel

particulate filter applications. The DMS500 remains the fastest available nanoparticle

size spectrometer with an output data rate of up to 10 Hz [246].

Figure E-2: Cambustion DMS500.

Dust Track. The DustTrak™ II Aerosol Monitor 8530 is a desktop battery-

operated, data-logging, light-scattering laser photometer that gives real-time aerosol

mass readings. It uses a sheath air system that isolates the aerosol in the optics

chamber to keep the optics clean for improved reliability and low maintenance. It

measures aerosol concentrations corresponding to PM1, PM2.5 or size fractions [247].


Figure E-3: DustTrak™ II Aerosol Monitor 8530.

Sayble. The CA-10 Carbon Dioxide Analyser measures CO2 in a range of

applications from respirometry to industrial gas monitoring. It features a dual-

wavelength infrared sensor that provides stable, fast response in a broad CO2

measurement range. Operation is intuitive and flexible, allowing easy use by a wide

range of users. High resolution of 1 ppm at atmospheric levels ensures trustworthy

results [248].

Figure E-4: CA-10 Carbon Dioxide Analyser.

experimental investigation of thermochemically …. farhad_hossain... · 2018. 1. 12. · farhad m...

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