CHARACTERIZATION OF BIODIESEL AS A FUEL IN A COMPRESSION IGNITION
(CI) ENGINE WITH ADDITIVES
MOHD HAFIZIL BIN MAT YASIN
A report submitted in partial fulfilment of the requirements
for the award of the degree of
Master of Mechanical Engineering
Faculty of Mechanical Engineering
UNIVERSITI MALAYSIA PAHANG
NOVEMBER 2012
v
ABSTRACT
Compression ignition engines have been used widely in the transportation sector and
power generation for the decades. These engines are less fuel consumed with higher brake
thermal efficiency. However, compression ignition engines produce higher pollution in
NOx and PM emission as well as cause several negative drawbacks to the environment.
Most countries in the world have regulated several regulations to reduce the emission from
the engines. Other than that, the introduction of biodiesel in the engines is beneficial and
proven to reduce the emission significantly. However, biodiesel has higher density and
viscosity with lower heating value as compared to mineral diesel. Fuel additives are among
other methods that proven to modify the properties of biodiesel to be comparable with
mineral diesel without doing any engine modification. Although fuel additives’ ability to
reduce harmful emissions is well known in the literature, the mechanism for these
additives is not well understood when operated in the four-stroke, four-cylinder diesel
engines. Two alcohol-based additives, methanol and ethanol were diluted with B 20 blend
(20% biodiesel + 80% mineral diesel) with the formulation of 5% by volume. The test
fuels; mineral diesel, B100 (palm-diesel), B20 blend and B20-alcohol blends (B20 E5 and
B20 M5) were investigated on a Mitsubishi 4D68 four stroke, four-cylinder water-cooled
diesel engine incorporating sensors for in-cylinder pressure measurement and
thermocouples. There were two operating modes dealing with these fuels, which the first
mode been conducted on increasing engine speeds at 50% throttle position. While as for
the second mode, these fuels were operated at three different engine loads, 0.05 MPa, 0.4
MPa and 0.7 MPa with the engine constant speed of 2500 rpm. The effect of test fuels on
brake power, brake specific fuel consumption (BSFC), brake thermal efficiency (BTE),
combustion (in-cylinder pressure, rate of heat release, cylinder temperature) and NOx, NO,
CO and CO2 emissions were investigated. Results found that the performance of diesel
engine improved with the use of alcohol (ethanol and methanol) in the B20 blends
especially in comparison to mineral diesel, B100 and B20. Overall, the results indicated
that when compared to mineral diesel, B100, B20, B20 E5 and B20 M5 have higher brake
thermal efficiency. The use of alcohol as a fuel additive in the B20 blend has improved the
combustion characteristics when the loads were applied to the engine. Besides, the exhaust
emission for the B20 E5 and B20 M5 were fairly reduced when compared to mineral
diesel.
vi
ABSTRAK
Enjin cucuhan mampatan telah lama digunakan secara meluas dalam sektor pengangkutan
dan penghasilan kuasa. Enjin ini menggunakan bahan api yang minimum dengan
kecekapan brek termal yang tinggi. Walaubagaimanapun, enjin cucuhan mampatan
menghasilkan pencemaran NOx dan zarah terampai (PM) yang tinggi serta kesan yang
negatif terhadap alam sekitar. Kebanyakan negara di dunia telah menguatkuasakan
beberapa peraturan untuk mengurangkan kadar pencemaran daripada enjin tersebut. Selain
itu, penggunaan biodiesel sebagai bahan api alternatif dalam enjin diesel dan terbukti untuk
mengurangkan kadar pencemaran. Walaubagaimanapun, biodiesel mempunyai nilai
ketumpatan dan kelikatan yang lebih tinggi serta nilai pemanasan yang lebih rendah
berbanding diesel mineral. Additif bahan api merupakan antara kaedah yang terbukti bagi
mengubahsuai ciri – ciri bahan api biodiesel agar setanding dengan diesel mineral tanpa
melakukan pengubahsuaian terhadap enjin diesel. Walaupun keupayaan additif untuk
mengurangkan pencemaran banyak dibincangkan namun mekanisme additif tersebut masih
belum difahami apabila digunakan dalam enjin diesel empat lejang empat silinder. Dua
additif jenis alkohol, etanol dan metanol telah dilarutkan bersama B20 (campuran 20%
biodiesel dan 80% diesel mineral) dengan formulasi campuran 5%. Bahan api campuran
bersama alkohol dan biodiesel-diesel (B20 E5 dan B20 M5), diesel mineral, B100 (palm-
diesel) dan B20 telah diuji menggunakan enjin diesel Mitsubishi 4D68 jenis 4 lejang 4
silinder dengan sistem penyejukan air yang dilengkapi penderia mengukur tekanan dalam
silinder serta termogandingan suhu. Terdapat dua jenis pengujian enjin menggunakan
bahan api tersebut; iaitu pengujian enjin pertama dijalankan dengan meningkatkan kelajuan
enjin bermula 1500 rpm sehingga 3500 rpm pada 50% kedudukan pendikit enjin.
Manakala pengujian enjin yang kedua, bahan api tersebut dioperasikan pada tiga bebanan
berbeza iaitu 0.05 MPa, 0.4 MPa dan 0.7 MPa menggunakan kelajuan enjin malar, 2500
rpm. Kesan penggunaan bahan api tersebut terhadap kuasa brek, penggunaan bahan api
brek khusus (BSFC), kecekapan brek termal (BTE), pembakaran (tekanan dalam silinder,
kadar penyingkiran haba, suhu silinder) dan penghasilan gas NOx, NO, CO dan CO2 telah
direkodkan dan di analisa dalam kajian ini. Keputusan eksperimen menunjukkan bahawa
prestasi enjin diesel meningkat dengan penggunaan alkohol (etanol dan metanol) dalam
bahan api B20 apabila dibandingkan dengan diesel mineral dan bahan api B20. Secara
keseluruhan, keputusan menunjukkan B100, B20, B20 E5 dan B20 M5 mempunyai
kecekapan brek termal lebih tinggi berbanding dengan diesel mineral. Penggunaan alkohol
sebagai additif dalam bahan api B20 telah meningkatkan ciri – ciri pembakaran dalam
silinder apabila bebanan dikenakan pada enjin. Selain itu, pengeluaran gas ekzos telah
berkurang bagi B20 E5 dan B20 M5 apabila dibandingkan dengan mineral diesel dalam
pengujian enjin tersebut.
vii
TABLE OF CONTENTS
Page
SUPERVISOR’S DECLARATION ii
STUDENT’S DECLARATION iii
ACKNOWLEDGEMENTS iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xiv
LIST OF FIGURES xv
LIST OF SYMBOLS xix
LIST OF ABBREVIATIONS xxi
CHAPTER 1 INTRODUCTION
1.1 Introduction 1
1.2 Overview of emission regulation and controls 4
1.3 Project overview 5
1.4 Problem statement 6
1.5 Objective of the study 6
1.6 Scope of the study 7
1.7 Research methodology 7
1.8 Report outline 9
viii
CHAPTER 2 LITERATURE REVIEW
2.1 Diesel engine 11
2.1.1 History of diesel engines 11
2.1.2 Types of diesel engine 12
2.1.3 Diesel engine applications 14
2.1.4 Diesel engine technology 15
2.2 Diesel and its properties 16
2.2.1 Cetane number 18
2.2.2 Viscosity 18
2.2.3 Density 19
2.2.3 Heating value 19
2.2.4 Aromatic content 20
2.2.5 Sulfur 20
2.2.6 Specific gravity (API Gravity) 21
2.2.7 Cloud point, pour point and cold filter clogging point 21
2.2.8 Flash point and vapour pressure 21
2.3 Diesel engine exhaust emissions 22
2.3.1 Oxides of nitrogen (NOx) 22
2.3.2 Carbon monoxide (CO) 24
2.3.3 Unburned hydrocarbons (UHCs) 24
2.3.4 Particulate matter (PM) 25
2.3.5 Polycyclic aromatic hydrocarbons (PAHs) 26
2.4 Biodiesel as an alternative fuel for diesel engines 27
2.4.1 Biodiesel production, policies and standardizations 27
2.4.2 Advantages of biodiesel use in diesel engines 32
2.4.3 Palm-diesel (palm methyl ester) as a future biodiesel fuel for
diesel engines
33
2.4.4 Performance of biodiesel as alternative fuels in diesel
engines
34
2.4.5 Exhaust emissions from the combustion of biodiesel 36
ix
2.5 Fuel additives 38
2.5.1 Types of fuel additives 39
2.5.2 Performance and emissions of biodiesel fuels with alcohol
based additives
40
2.6 Engine testing analysis 42
2.6.1 Brake power and torque 42
2.6.2 Brake specific fuel consumption (BSFC) 43
2.6.3 Brake mean effective pressure (BMEP) 44
2.6.4 Indicated mean effective pressure (IMEP) 44
2.6.5 Brake thermal efficiency (BTE) 45
2.6.6 Correction factors 45
2.7 Combustion analysis 46
2.7.1 Ignition delay period 47
2.7.2 Premixed burning period 47
2.7.3 Diffusion burning period 48
2.7.4 After burning period 48
2.7.5 Combustion summary 49
2.8 Measured and calculated parameters in the combustion analysis 49
2.8.1 In-cylinder pressure 49
2.8.2 Rate of heat release (RoHR) 50
2.8.3 Air flow ratio (AFR) 52
2.8.4 In-cylinder gas temperature 53
2.8.5 Mass fraction burn (MFB) 53
2.9 Summary 54
CHAPTER 3 EXPERIMENTAL FACILITY SET-UP AND
APPARATUS
3.1 Introduction 55
x
3.2 Engine testing apparatus 57
3.2.1 Engine mapping performance 57
3.2.2 Dynamometer and drive trains 59
3.2.3 Engine and dynamometer cooling systems 62
3.2.4 Fuel delivery and measurement system 65
3.2.5 Engine wiring 66
3.2.6 Air intake measurement system 67
3.2.7 Temperature monitoring and measuring 68
3.2.8 In-cylinder pressure data acquisition 68
3.2.9 Ambient temperature and relative humidity data acquisition 73
3.3 Exhaust gas monitoring and analysis 74
3.3.1. Exhaust gaseous measurement 74
3.4 Test fuels and lubricant 76
3.5 Test additives 77
3.6 Test-operating conditions 78
3.7 Test matrices 79
CHAPTER 4 FUEL PROPERTIES AND ENGINE PERFORMANCE
OF THE DIESEL ENGINE
4.1 Introduction 80
4.2 Physical, chemical and other related properties of the test fuels 80
4.2.1. Density 81
4.2.2 Viscosity and lubricity 81
4.2.3 Heat value 82
4.2.4 Cetane number 82
4.2.5 Summary 83
4.3 Engine performance 83
4.3.1 Engine performance curve 84
xi
4.3.2 Engine brake power results 86
4.3.3 Brake specific fuel consumption (bsfc) 88
4.3.4 Brake thermal efficiency (BTE) analysis 90
CHAPTER 5 COMBUSTION CHARACTERISTICS OF THE
ENGINE
5.1 Introduction 92
5.2 Combustion characteristics of the engine 92
5.3 Peak cylinder pressure for the test fuels 93
5.4 Rate of pressure rise (RoPR) for the test fuels 96
5.5 Cylinder temperature for the test fuels 100
5.6 Peak cylinder pressure against volume displacement, dm3 103
5.7 Rate of heat release (RoHR) for the test fuels 107
5.8 Mass fraction burned (MFB) for the test fuels 111
5.9 Summary 126
CHAPTER 6 EMISSION CHARACTERISTICS OF THE
ENGINE
6.1 Introduction 116
6.2 Exhaust emissions 116
6.3 Brake specific NOx (BSNOx) emissions 118
6.4 Brake specific NO (BSNO) emissions 120
6.5 Brake specific carbon monoxide (BSCO) emission 121
6.6 Brake specific carbon dioxide (BSCO2) emission 123
xii
CHAPTER 7 CONCLUSION
7.1 Conclusion 125
7.2 Recommendations 127
7.2.1 Accommodate more pressure transducer 127
7.2.2 Simulation versus experiments 127
7.2.3 Transient test condition 128
7.2.4 Test at higher biodiesel proportions 128
REFERENCES 129
APPENDICES
A1 Past, current and proposed future for European emission standards 140
B1 ASTM and MS test methods for diesel fuel properties 141
B2 Properties of different vegetable oils (Ayhan Demirbas, 2003) 142
B3 Fatty acid composition (% mass) from different types of biodiesel
oils (Singh & Singh, 2010)
143
C1 ECB-200 dynamometer specification 144
C2 Specification of dynamometer cooling tower 145
C3 AIC fuel flow meter specification 146
C4 Specification of Meriam laminar flow element (LFE) 147
C5 K-type thermocouple probe specification 148
C6 Charge module specification 149
C7 Specification of Kistler crank angle encoder type 2613B 150
C8 DEWE-800 DAQ system specification 151
C9 Specification of DEWE-Orion 1624 data acquisition card 152
C10 EL-USB-RT data logger specification 153
C11 Test-operating conditions 154
C12 Test matrix for fuel testing at the increasing speeds with a partial 155
xiii
engine throttle position
C13 Test matrix for fuel testing at three different engine loads with a
constant engine speed of 2500 rpm
156
D1 Measured fuel properties of mineral diesel, B100 (palm-diesel),
B20, B20 E5 and B20 M5
157
D2 Engine performance results for test fuels 158
E1 Brake specific nitrogen oxide (NOx) concentrations (g/kW-hr) 159
E1 Brake specific nitrogen monoxide (NO) concentrations (g/kW-hr) 159
E1 Brake specific carbon monoxide (CO) concentrations (g/kW-hr) 159
E2 Brake specific carbon dioxide (BSCO2) concentrations (g/kW-hr) 160
F1 List of publications 161
xiv
LIST OF TABLES
Table No. Title Page
3.1 Engine specifications 58
3.7 In-cylinder pressure transducer specification 70
3.13 Specification for Signal Instrument gas analyzer 75
3.14 Accuracy measurement for Kane gas analyzer 75
3.15 Test fuels properties 77
3.16 Physical properties of ethanol and methanol 78
xv
LIST OF FIGURES
Figure No. Title Page
2.1 Four-stroke diesel engine cylinder cycles (Shankar,
2011)
13
2.2 Comparison between DI and IDI diesel engine (Bosch,
1996)
14
2.3 Typical diesel chemical composition Cetane or n-
hexadecane, C16H34
17
2.4 Formation of particulate matter (PM) (Maricq, 2007) 26
2.5 Polycyclic aromatic hydrocarbons (PAHs) molecule
structure (Gilbert, 2004)
27
2.6 A basic transesterification process (Tyson, 2009) 28
2.7 A transesterification process with methanol as a catalyst
(Ma & Hanna, 1999)
29
2.8 Palm oil is transesterified into palm-diesel 34
2.9 Pressure curve in the cylinder 50
3.1 Engine testing facility lay out 56
3.2 Engine test rig 57
3.3 Engine characteristics at a partial engine throttle position 58
3.4 (a) Dynalec dynamometer (b) Throttle position lever 59
3.5 A Dynalec dynamometer controller 60
3.6 (a) Engine dynamometer performance curve (b) Engine
dynamometer torque curve
61
xvi
3.7 A hook joint cardan prop shaft 62
3.8 Engine cooling system diagram 63
3.9 (a) Engine cooling system (b) Dynamometer cooling
tower
64
3.10 (a) AIC fuel flow meter (b) A board computer type BC-
3033
65
3.11 Engine wiring diagram 66
3.12 Air intake measurement in a diesel engine 67
3.13 (a) Thermocouple locations at the exhaust extractors (b)
Thermocouple locations at air intake and engine cooling
system
68
3.14 A schematic diagram of the engine test bed and
instrumentation
69
3.15 A Kistler 6041 ThermoCOMP pressure transducer 70
3.16 (a) Kistler crank angle encoder type 2613B1 (b) Kistler
signal conditioner type 2613B2
71
3.17 Schematic diagram and wirings of in-cylinder pressure
data acquisition
71
3.18 Cylinder pressure measurement using DEWECa
graphical user interface (GUI)
72
3.19 (a) EL-USB-RT data logger (b) EL-USB-RT software
logger interface
73
3.20 (a) A Signal instrument gas analyzer (b) A KANE gas
analyzer
74
3.21 Gas analyzer flow channel location 76
4.1 Density of the test fuels (M.H. Mat Yasin, 2012) 81
4.2 A Mitsubishi 4D68 diesel engine performance curves at a
partial engine throttle position
85
xvii
4.3 Engine brake power at increasing engine speeds, partial
throttle position
87
4.4 Brake specific fuel consumption (BSFC) for the
increasing speeds at a partial throttle position
88
4.5 Brake thermal efficiencies (BTE) relative to increasing
speeds at 50% throttle position
90
5.1 Peak cylinder pressure curve with engine load, 0.05 MPa
at 2500 rpm
93
5.2 Peak cylinder pressure curve with engine load, 0.4 MPa
at 2500 rpm
94
5.3 Peak cylinder pressure with engine load, 0.7 MPa at 2500
rpm
95
5.4 Rate of pressure rise with engine load, 0.05 MPa at 2500
rpm
97
5.5 Rate of pressure rise with engine load, 0.4 MPa at 2500
rpm
98
5.6 Rate of pressure rise with engine load, 0.7 MPa at 2500
rpm
99
5.7 Cylinder temperatures at with engine load, 0.05 MPa at
2500 rpm
100
5.8 Cylinder temperatures with engine load, 0.4 MPa at 2500
rpm
101
5.9 Cylinder temperatures with engine load, 0.7 MPa at 2500
rpm
102
5.10 Peak in-cylinder pressure against volume displacement
with engine load, 0.05 MPa at 2500 rpm
104
5.11 Peak in-cylinder pressure relative to volume
displacement with engine load, 0.4 MPa at 2500 rpm
105
5.12 Peak in-cylinder pressure against volume displacement
with engine load, 0.7 MPa at 2500 rpm
106
xviii
5.13 Rate of heat release (RoHR) with engine load, 0.05 MPa
at 2500 rpm
108
5.14 Rate of heat release rate with engine load, 0.4 MPa at
2500 rpm
109
5.15 Variations of heat release rate with engine load, 0.7 MPa
at 2500 rpm
110
5.16 Mass fraction burned (MFB) with engine load, 0.05 MPa
at 2500 rpm
112
5.17 Mass fraction burned (MFB) with engine load, 0.4 MPa
at 2500 rpm
113
5.18 Mass fraction burned (MFB) with engine load, 0.7 MPa
at 2500 rpm
114
6.1 BSNOx emissions with engine loads for different test
fuels at 2500 rpm
118
6.2 BSNO emissions with engine loads for different test
fuels at 2500 rpm
120
6.3 BSCO emissions with engine loads for different test fuels
at 2500 rpm
121
6.4 BSCO2 emissions with engine loads for different test
fuels at 2500 rpm
123
xix
LIST OF SYMBOLS
g m/s2 Acceleration due to
gravity
ma kg/s Air mass flow rate
l - Air excess ratio
N rpm Crankshaft rotational
speed
r kg/m3 Density
μ kg/ms Dynamics viscosity
Pb kW Engine brake power
Tb Nm Engine brake torque
h % Engine thermal efficiency
mf kg/s Fuel mass flow rate
F Fuel-to-air equivalence ratio
V cm3 Instantaneous volume of the
engine cylinder
p bar In-cylinder pressure
_q delay deg Ignition delay
k joules Kinetic energy
pmax bar Peak in-cylinder pressure
pdrop bar Pressure drop
g Ratio of specific heats
Rswirl - Swirl ratio
t s Time
Total m kg/s Total air mass flow rate
V V Voltage signal
CHAPTER 1
INTRODUCTION
1.1 INTRODUCTION
Fossilized energy has contributed the most impact of the economic development
in the world through the transportation sector and energy conversion sector. Middle
East region has supplied about half of oil production in the world and the rest come
from the central Asia region and America continent. However, the uncertain of oil
prices have given the side effect to the world economic with the factors of instability
political situation especially in the Middle East region and the decrease of crude oil
production reserve. This scenario has started in early 1970 with the oil price increased
to US Dollar 110 per barrel and another highest oil price recorded was in 2009 with
over US Dollar 135 per barrel (Hamilton, 2011).
The erratic increase in oil prices was reflected due to Arab-Israel War and the
Iran revolution that held between year 1965 and 1975. The economics of depending
mostly on imported fuels have grown in recent years as oil prices have become
unstable, doubling in less than two years the price of 2004 and reaching in 2006 oil
prices (Aleklett et al., 2010). This trend of events has shown that the oil prices will not
be permanent and could be escalate again depending on world instability situation and
increasing demand factor. Uncertain oil prices in the oil market have enhanced the
growth of commercial viability of alternatives fuels that can replace the fossilized fuels
without any modification to the engines.
2
Moreover, in the environmental side, the use of fossilized energy especially in
the transportation where at least 25% has contributed to the increasing of toxic gas and
affected and greenhouse emission. With the growing awareness of energy-pollution and
a climate change consequence, as well as complying to the Kyoto Protocol that targets
the use of less energy pollution from emitting energy source which is a clear message
to the global for a change towards more sustainable energy production and conservation
(Goldemberg J., 2004).
In year 2030, transportation sector will be the most emitting factor for the world
with the growth demand of vehicles on the road (Birol, 2010). Emission contents which
released from the vehicles show the linear scale with the fuel consumption where
today’s vehicles are mostly running with fossilized fuels. Following the trend, the
increase of GHG also will be projected to 50% by 2030. The use of fossilized fuels has
released the toxic gas including carbon dioxide (CO2), nitrogen oxide (NOx), unburned
hydrocarbon (UHC) and unseen particulate matters. This combination of harmful
portion can cause unhealthy air that affects to the human respiratory system and thick
fog that surround the area with low vision range. According to Vardoulakis et al., the
higher contents of particulate can result cancer, respiratory diseases such as asthma,
allergic and others that can affect the quality of health (Vardoulakis, Phoon, &
Ochieng, 2010).
With those main conflicts that related with the fossilized oil, new technology
discoveries have been promoted by researchers in order to overcome the dependent on
fossilized fuels. There are astonishing efforts to promote the use of solar power, hybrid
with less consumption of fuel, hydrogen fuel cell, biofuels and others to the people.
Still not many people are ready to the complete changing where the cost is still
expensive in terms of cost, not truly practical and lots more researches needed to
improvise those methods. Nevertheless, the suitable replacement and quite similar to
the fossilized fuels is the biodiesel fuels that extracted from the plants and animal fats
in term of characteristics, properties and without any modification of the engine.
In recent years, there are two main types of biofuels which refer to first of
generation biofuels called bioethanol, which is derived from starch or sugar such as
3
cane, corn and sugar beet, and second generation biofuels is biodiesel, derived from
animal fats and vegetable oils, for example from palm oil, jathropa, soy bean, rapeseed
oil, neem oil and others (Brown, 2006.). In this case, the European Union has shown
the full commitment and support for the biofuels, with targeting the demand in biofuels
for the transportation sector to 5.75% by 2010 and projected to 20% by 2020 (IEA,
2005). The Biofuels Directive issued by the European Commission in 2003 set the
target to implement the use of biofuels in EU countries and committed in achieving
their targets (European Parliament and Council Directive, 2003) and following the
proposed EU policies in 2006 to cultivate the use of biofuels massively.
Biodiesel is the generic terms for all types of fatty acid methyl ester (FAME)
which considered other organic renewable alternative fuel that can be used directly in
any mineral diesel engine with little or no modification (A. Demirbaş, 2008). They are
transesterified-vegetable oils that have been adapted to the properties of fossilized
diesel fuel and considered to be superior since they have a higher energetic yield been
combusted in the diesel engine . Current compression ignition (diesel) engines are able
to operate upon a wide range of fuels due to its specific characteristic, which is internal
combustion under a variety of operating conditions. In a world of resources, it seems
prudence to focus upon fuels, which are potentially efficient and renewable, like bio-
fuels.
Besides this advantage in fuel flexibility, compared to those of spark ignition
(petrol) engine, diesel engine can offer better engine durability, higher thermal
efficiency and more economical fuel consumption (Ayhan, 2009). Through centuries,
diesel engines were used in many sectors such as in transportation and industries.
Diesel engines usually used in heavy industries, light heavy automotive, ships,
locomotive transportation such as truck and buses, and farm machines such as
lawnmowers and tractors. The latter relates to fuel economy savings that can potentially
produce less carbon dioxide (CO2) emission. Diesel engines are therefore, part of a
long-term solution to global warming.
4
Currently, diesel engines use fossilized fuel in its combustion process.
However, it is estimated that the fossil fuel supply will decrease in the future.
Petroleum demand around the world is projected to increase by 50% by 2030 (Birol,
2010). This happens due to maximum production of the fuel, which causes fuel reserve
decreases drastically to a minimum level. Eventually it leads to demand succeed supply
and finally increase the fossil fuel price. There are a few alternatives to overcome those
problems such as the use of hybrid engine to minimize the fuel consumption and the
exhaust emission; improvement on the diesel engine with modifications such as HCCI
(Homogenous Charge Compression Ignition) engine and others. However, those
solutions are still under continuous research and not yet be produced commercially
even for hybrid.
The most preferred solution is using the renewable alternative fuels that can fuel
the diesel engine without difficulty. All biodiesels are not produced by the fossil fuel
distillation but are extracted through a chemical process called transesterification
process to produce methyl ester or ethyl ester. Those alternative fuel properties are
similar to diesel fuel but produce less emission, same or higher performance than the
diesel fuel itself (Ayhan, 2011a; M. Fatih, 2011; Nagi, Ahmed, & Nagi, 2008; Shahid
& Jamal, 2008).
1.2 OVERVIEW OF EMISSION REGULATION AND CONTROLS
Diesel engines are associated with combustion noise, engine vibration, and the
problem of nitrogen oxides (NOx)- particulate matter (PM) trade-off emissions. Table
1.1 (Appendix A1) illustrates how the European Union emission standards for heavy-
duty diesel engines have tightened since EURO I, which came into force in 1992.
Researchers have made lots of effort to reduce toxic and greenhouse gases emitted from
these engines. Several advanced technologies for clean diesel engines have been
introduced and been categorized into four strategies: (i) fuel and fuel additive, (ii) fuel
injection systems including in-cylinder technology, (iii) lubricant oil development, and
(iv) exhaust gas after-treatment devices. All these approaches have been developed into
more technology advanced levels since internal combustion (IC) engines are invented
5
with many researchers and engine manufacturers have greatly involved in improving
the technology behind the diesel engine.
1.3 PROJECT OVERVIEW
The use of renewable alternative fuels to replace the conventional fossil fuels
and its potential is well known and has been studied for many years in Asia, Europe
and United States. This is proven by the certified significant results from many
researches which are conducted and regulations and standards enforced by various
agencies. However, in Malaysia, the use of alternative fuel is still at doubtful stage due
to lack of support from the public, the government and the private sectors. This
research aims to determine the performance, combustion and emission characteristics
generated by a multi-cylinder diesel engine running on biodiesel blend, B20 with the
presence of methanol and ethanol as alcohol-based additives. The test fuels used in this
research are B100 which is palm-diesel (palm methyl ester) originated from palm oil,
B20 (20% palm-diesel mix with 80% mineral diesel), B20 alcohol-based blends with
5% by volume (B20 E5 and B20 M5) and mineral diesel as a baseline fuel for further
comparison.
In this study, there were two types of test operating modes were conducted on a
multi-cylinder diesel engine with the test fuels. Subchapter 3.3 describes those test-
operating conditions in terms to determine the engine performance, combustion and
emission characteristics for the diesel engine. Among the measured parameters
considered were engine torque, engine speed, fuel consumption, exhaust temperatures,
volumetric airflow, in-cylinder pressure and crank angle. Those data were used for
computing the calculated parameters within the engine performance included brake
power, brake specific fuel consumption (BSFC), brake thermal efficiency (BTE) and
brake mean effective pressure (BMEP). Besides, these also included the computed
combustion characteristics for instance rate of heat release (RoHR), rate of pressure rise
(RoPR), mass fraction burned (MFB), and in-cylinder gas temperature. In addition,
different level of exhaust emission formation were measured from the diesel engine
6
fuelled with the test fuels to determine which test fuel has better engine performance
with lower emission reduction.
1.4 PROBLEM STATEMENT
Most engine testing on biodiesel are commonly conducted on single cylinder
diesel engine, which determines engine performance and emission characteristics. This
provides a better understanding on how well the single cylinder diesel engine operates
with the biodiesel. However, single cylinder diesel engines are designed mostly for the
agricultural purposes but not in the transportation sectors. Insufficient information on
biodiesel operates with multi-cylinder diesel engine has motivated to determine the
research gaps that could incorporate through this study. In addition, the use of biodiesel
operates with multi-cylinder diesel engine is not a popular method due to its higher fuel
consumption when engine testing is conducted. Furthermore, it requires appropriate
testing apparatus include larger capacity dynamometer and sophisticated
instrumentation system. Because of that reasons, some research gaps have been
considered in terms to construct the need of this study. Research gaps in this study are
outlined as:
i. Palm-diesel blend, B20 used as the main subject for the study.
ii. Palm-diesel blend, B20 dilutes with alcohol additives, ethanol and
methanol in 5% by volume, designated as B20 E5 and B20 M5.
iii. The use of a multi-cylinder diesel engine operates with mineral diesel as
a baseline fuel, B100 (palm-diesel), B20 and its alcohol blends (B20 E5
and B20 M5).
1.5 OBJECTIVE OF THE STUDY
To determine the engine performance, combustion and exhaust emission
characteristics of mineral diesel, B100 (palm-diesel), B20, B20 E5 and B20 M5 which
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are palm-diesel blend fuels with ethanol and methanol as alcohol fuel additives in a
compression ignition (CI) engine.
1.6 SCOPE OF THE STUDY
i. Literature reviews on application of biodiesel and the practical use of
fuel additives in engine testing
ii. Develop and commission an engine test cell facility fully equipped with
the instrumentation system.
iii. Evaluate the psychochemical properties of mineral diesel, B100 (palm-
diesel), B20, B20 E5 and B20 M5.
iv. Conduct the engine testing at the increasing engine speeds from 1500
rpm to 3500 rpm with a constant partial throttle position on the multi-
cylinder diesel engine fueled with the test fuels to determine engine
performance, combustion characteristics and exhaust emission.
v. Conduct the engine testing at three different engine loads, 0.05 MPa, 0.4
MPa and 0.7 MPa with a constant engine speed of 2500 rpm on the
multi-cylinder diesel engine fueled with the test fuels to determine
engine performance, combustion characteristics and exhaust emission.
vi. Evaluate the engine performance, combustion and exhaust emission
characteristics on the multi-cylinder diesel engine operated with the test
fuels.
1.7 RESEARCH METHODOLOGY
The research starts with literature studies on mineral diesel and biodiesel
especially palm-diesel. In this study, literature reviews focus to the engine performance,
combustion and exhaust emission characteristics of the biodiesel and biodiesel-alcohol
blend fuels; running on a single cylinder and multi-cylinder diesel engines. Literature
reviews also cover the psychochemical properties of the biodiesel and biodiesel-alcohol
blend fuels include density, flash point, pour point, Cetane number and other properties.
The use of alcohol as additives in the diesel and biodiesel blend fuels is covered in the
next literature review.
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In the experimental set up, the research has been divided into two sections
where one section is provided for the fuel analysis. Suitable methods and apparatus
have been assigned for the fuel analysis according to the current standard. While the
other section focuses on the engine test rig set up, this includes the measurement and
analysis of the engine performance, combustion characteristics and exhaust emissions.
The engine test rig set up follows the standard of SAE J1349 - Engine Power Test
Code—Spark Ignition and Compression Ignition—Net Power Rating as well as SAE
J1312 - Procedure for Mapping Performance—Spark Ignition and Compression
Ignition Engines to meet the requirement for the standard engine testing. Parameters
such as ambient temperature, inlet air supply pressure and temperature, fuel
temperature at fuel tubing, oil sump pressure and temperature, exhaust temperature
have also been measured and recorded in the engine test rig. The measured data used to
compute the observed brake power, corrected brake power, corrected BMEP, mass air
flow, volumetric fuel flow rate, brake specific fuel consumption (BSFC) and brake
thermal efficiency (BTE).
A Mitsubishi four-cylinder, four stroke water-cooled diesel engine has been
coupled to a 150 kW eddy current dynamometer to conduct the fuel testing in this study.
It has been incorporated with a DEWE-800 DAQ system from DEWETRON to
measure, record and analyse the results include exhaust temperatures, in-cylinder
pressure and crank angle degree (CAD) during the engine testing. In addition, two
types of test operating modes have been performed on the current multi-cylinder diesel
engine fuelled with mineral diesel, B100 (palm-diesel), B20, B20 E5 and B20 M5
blend fuels. The results mainly consist of engine performance, combustion and exhaust
emission characteristics. Furthermore, as for the requirements in the fuel testing, the
chemical properties for fuels and additives have been determined using chemical lab
apparatus following stringent procedure by the ASTM standards.