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04/04/2017

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Session 3: Novel fuels

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04/04/2017 © The University of Sheffield

Dr. S. Blakey

Objectives

• Inform on current position

• Introduce concept of “fit for purpose” testing + examples

• Set the scene for technical requirements of fuel in the future


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… from yesterday – why?

• Security of supply

• Environmental Sustainability

• Keep in mind, drivers for novel alternative fuels are not technical alone (as will be discussed here) but also economic / substantiality criteria.

• Part of this is the pull to novel automotive diesels – bigger market – not as difficult to get into. New starters are likely to ignore Jet and make diesel.


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04/04/2017

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0

5

10

15

20

25

30

35

40

800 1000 1200 1400 1600 1800 2000

Turbine entry temperature (K)

Over

all pre

ssure

rat

io .

WR1

DerwentSapphire

Avon

Olympus 101 Adour

Olympus 22R Pegasus 11

RB199-101

Spey

V2527-A5

Early AF work• Low pr, T3 dominated

by physical

characteristics of fuel

• High pr, T3 dominated

by fuel chemistry /

mixing

• Broad range of fuels

tested (12 – 15%H

wt.)

1990 study

1980 study

Engines certified in 2000

• Focus on Combustion alone

- not other properties

Synthetic fuels

• Aviation kerosene

• Narrower Boiling ranges

• FT / HEFA

• (But would be broader if not for Diesel)

• Specific isomers

Sugar / fermentation

Microbial routes


5

0

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90

100

0 1 2 3 4 5 6 7 8 9 10

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90

100

0 1 2 3 4 5 6 7 8 9 10

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100

0 1 2 3 4 5 6 7 8 9 10

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0 1 2 3 4 5 6 7 8 9 10

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0 1 2 3 4 5 6 7 8 9 10

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0 1 2 3 4 5 6 7 8 9 10

Significance of change

• Boiling range

• Freeze point

• Clear reduction in density Change in PM emissions Interaction with fuel system

• Seal compatibility, thermal stability, …

• But… potentially something simpler to predict!


6

Loss of aromatic fraction

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0

20

40

60

80

100

%m

as

s

HDCJ #1

Alternative fuels: changes to fuel composition

0

20

40

60

80

100

%m

as

s

Conventional fuel #1

0

20

40

60

80

100

%m

as

s

HEFA #1

0

20

40

60

80

100

%m

as

s

pure FT-SPK #1

0

20

40

60

80

100

%m

as

s

DSHC/SIP#1•

•

0

20

40

60

80

100

%m

as

s

ATJ-SKA#1

0

20

40

60

80

100%

ma

ss

SK #1

Source: FAA

FT‐SPK: FT Synthetic Paraffinic Kerosene

HEFA: Hydroprocessed Esters and Fatty

Acids

SIP: Synthesized Iso-Paraffins (formerly

Direct Sugar to Hydrocarbons) – limited to

10% blends

ATJ – Alcohol to Jet Synthesized Paraffinic

Kerosene (also ATJ-SKA, containing

aromatics)

HDCJ – Hydroprocessed Depolymerized

Cellulosic Jet (Pyrolysis amongst others)

HDO-SK Hydrodeoxygenated Synthesized

Kerosene

Fuel Composition Change? Fuel properties

Physical mechanisms Atomisation, Chemical kinetics,

biocontamination, low temp

performance,…

Combustor performance LBO, Altitude relight, gaseous

emissions, PM emissions,

acoustics…

Interaction with fuel system Hot end durability, Seal

compatibility, thermal stability,

lubricity,


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Aromatic content

Paraffinic groups

Carbon number

distribution…

Pathways and fuels


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04/04/2017

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Reality check

• One size doesn’t fit all – diversity is good?

• Many small new players – maintaining quality?

• Environmental sustainability of feedstock

• Beyond specification testing


10

M. Rumizen, (2017)

US perspective


11

J. Hileman, (2017)


12

J. Hileman, (2017)

04/04/2017

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13

J. Hileman, (2017)


14

J. Hileman, (2017)

Reality check

• One size doesn’t fit all – diversity is good?

• Many small new players – maintaining quality?

• Environmental sustainability of feedstock

• Beyond specification testing


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Novel?


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A. Roth (2017)

Efficiency

• Photosynthesis: is inefficient for the harnessing solar energy

• Less than 1% overall efficiency

• Solar-to- fuel around 9%


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A. Roth (2017)

Using waste streams


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J, Harmon, (2017)

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19

J, Harmon, (2017)

Generic Properties

• Simpler chemistries potentially something simpler to predict!

• Significant amounts of data now available for the performance of novel fuels –trends are emerging…

• Where possible these should be exploited to reduce requirements for testing.


20Moses, (2016)

Generic Properties


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600

650

700

750

800

850

900

-50 0 50 100 150 200

Den

sity

(kg

/m^3

)

Temperature (degC)

Octane (C8)

Dodecane (C12)Decane (C10)

Benzene (C16)

CRC Jet A-1 average

• Build up performance from GCxGC

• Applicable where models for properties exist / significant amounts of fundamental data exists.

• Much simpler for well defined properties.

• Issues with extrapolation

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200

220

240

260

280

300

320

340

10 15 20 25 30

Wall

tem

pera

ture

(d

eg

C)

Rise in Bulk fuel temperature (degC)

Baseline

Baseline-Dittus-Boelter

GtL

GtL-Dittus-Boelter

Stage 1

Stage 2

Stage 3

Stage 4

Bulk properties not in spec.

• Heat transfer characteristics

• Not Jet fuel as we know it…

• Uncertainty in k measurement


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Calculated based on extrapolated physical properties andDittus-Boelter correlationUncertainty in k large ±25%?*

*Moses, C., et al., IASH 2011

Fuel at 180C

What is a Fit for Purpose test?

• Scaled down testing to assess technical suitability for

• properties not supported by the specification

• Properties beyond the specification

• no-one has agreed the conditions that show FFP

• all done by comparison


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Techniques

• Scaled testing

• Using scaled down experiments – cost / availability of AF fuels

• Test still need to be representative – limits of scale?

• Fit For Purpose testing

• Modelling to bridge …

Initial Population

Fitness Function

Objective Function

Filter Function

New Population

Parent pop

Children pop

Intermediate pop

GA Operations (Tournament, Crossover, Mutation) and

construction of Intermediate population

Old Population

Sending the whole population for GA

Operations

Intermediate pop

Copy

Evaluation and return

fitness

Evaluation and

return fitness

04/04/2017

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Assessing emissions performance

• APU engine as test vehicle• RR Artouste MK113

• Honeywell GTP GTCP85

• Wide range of AFs tested, both commercial and fundamental programmes

• Standard gaseous emissions

• PM and UHC speciation

• Smaller scale testing for smoke

• Modelling – allows scaling of results

Examples

Impact on PM


26

Lobo et al. (2015)

APU

Main engine start

Mass

• APU engine results

• SAE AIR 6241 Specification

• Mass based – Artium LII-300

• Number – AVL APC

• Low aromatics challenge for

seals – system needs to be

assessed multidimensionally

APU

Main engine start

Number

Assessing seal performance?

• Doesn’t leak!

• Result artefact of test:

• Only capable relative ranking

• Static - Volume swell, diameter change, hardness, mass

• Discrete dynamic - Cycle then perform static test at intervals

• Continuous dynamic tests - Stress Relaxation / temperature cycling


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Examples

http://pubs.acs.org/doi/10.1021/acs.energyfuels.5b01758

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paraffinssaturated and linear chains

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

paraffinssaturated and linear chains

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

iso-paraffinssaturated and branched chains

C

H

C

C

C

H

C

H

H

C

H

C

C

H

C

C

C

H

C

C

H

C

H

H

C

H

H

iso-paraffinssaturated and branched chains

C

H

C

C

C

H

C

H

H

C

H

C

C

H

C

C

C

H

C

C

H

C

H

H

C

H

H

0.7

0.8

0.9

1

1.1

1.2

0 40 80 120 160

F/F

0

Time, hrs

Change in SPK


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Seal swell

Seal relaxation / polymer extraction

Nitrile

Liu, Wilson, Advances in Mech. Eng, 2012

Elastomer Comp. conclusions

• Increase in SPKs in blends can reduce swell

• Volume of decalin required to swell nitrile O-ring in order to be comparable to Jet A-1 is too high (over 60%)

• Temperature effects – low temperature performance?

• Selection of specific components (cyclic paraffins / aromatics can provide swell)

… but what other FfP properties will be affected by this?


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Assessing thermal stability

• Not possible to sum up in single property of fuel / system interaction

• Artefact of test (again!)

• Static – Flask Oxidation

• Discrete Flowing - JFTOT

• Continuous Flowing – HiReTSand research rigs & large scale simulators


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Examples

http://en.wikipedia.org/wiki/File:Nitrile_Butadiene_Rubber.pn

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Scale and Thermal Stability


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Fue

l vo

lum

e (

L)

tim

e o

r co

st

Engine bed tests

Flight tests

Flow tests

Static tests

0.1

Simulator rig tests

1

10

102

103

104

105

a. Stainless-steel tubing before testing

b. Stainless-steel after 24 hours

**S97112

0.0

0.1

0.2

0.3

0.4

0.5

0.6

A

b

s

o

r

b

a

n

c

e

1000 1500 2000 2000 3000 4000

Wavenumbers (cm-1)

Approach to reality

QCM

SEM

FTIR

ICOT

After Spence Taylor (2008)

0

10

20

30 0

50

100

0

50

100

150

Time (min)

Run 5, 1000ppm + 400ppm water

Distance fromDatum (mm)

De

lta

Te

mp

era

ture

(d

eg

C)

Small scale: HiReTS (IP/EI 482)

Flow

Final ΔT

Min ΔT

• Flow through 250m 150mm heated capillary

• Fuel heated to 290C at outlet

• Temp measured externally

• Total HiReTS number

• More to be gained by using complete data set

Time (mins)

Blakey et al., IASH 2011

0

10

20

30 0

50

100

0

50

100

150

Time (min)

Run 5, 1000ppm + 400ppm water


De

lta

Te

mp

era

ture

(d

eg

C)

Small scale: HiReTS (IP/EI 482)

Flow

Final ΔT

Min ΔT

• Flow through 250m 150mm heated capillary

• Fuel heated to 290C at outlet

• Temp measured externally

• Total HiReTS number

• More to be gained by using complete data set

Time (mins)


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Conventional fuel


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• Spec test - Pass / fail, Fit for Purpose - quantative

• What is a conventional fuel?

• Presence of Sulphur, hetroatomic species and other leftovers after refining process.

• Careful selection of baseline required

0

10

20

30 0

50

100

0

10

20

30

Time (min)

IBC 08

Distance from Datum (mm)

De

lta

Te

mp

era

ture

(d

eg

C)

0

5

10

15

20

25

30 0

20

40

60

80

100

120

0

50

100

150

Time (min)


De

lta

Te

mp

era

ture

(d

eg

C)

Description HiReTS

Total No.

HiReTS

Peak No.

Straight run Jet A-1 605 72

Hydrotreated Jet A-1 104 21

Pure SPKs

• Very high thermal stability

• Lack of “other” species

• Lack of saturated bonds


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0

10

20

30 0

50

100

0

20

40

60

80

Time (min)

0ppm


De

lta T

em

pe

ratu

re (

de

gC

)

Description HiReTS

Total No.

HiReTS

Peak No.

Neat GtL 7 4

Aromatics


• GtL base

• Addition of aromatic components (more C than H)


0

10

20

30 0

50

100

0

20

40

60

80

Time (min)

10000ppm


De

lta T

em

pe

ratu

re (

de

gC

)

1000ppm

Description HiReTS

Total No.

HiReTS

Peak No.

GtL + 2% Toluene 19 4



GtL + 16% Tetralin 40 6

GtL + 8% Naphthalene 58 10

GtL + 1% m-toluidine 645 72

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Thermal Stability Conclusions

• Move to synthetic fuels beneficial

• Not all aromatics are bad – careful selection of blend

• High(er) impact of trace components

• Continued assessment required

• Can benefit result in improvements in engine hardware?

• Challenge: if all future engines were designed to take advantage of these good new fuels, new engines would still have to cope with the overwhelming volume of “conventional” jet fuel, or else have fuel supply issues


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Conclusions

• Wider fit for purpose testing well supported by D4054 (Novel Fuels Approval Process)

• Component by component selection is a reality

• Research effort required

• Can specification envelope be widened?

• Imposed limit on aromatics for seal swell is not the only solution

• Impact beyond FfP tests will need to be assessed


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Upcoming questions

• Inside Specification box – how far can we go?

• Effect of increasing isomerisation

Boiling point range, LBO, altitude relight…

• Effect of lower levels of aromatics or which ones?

Fuel gauging, range / payload, emissions, seal performance, thermal stability…

• Outside Specification box

• Cost / Benefit needs assessing – no downside


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04/04/2017

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Session 3: Novel fuels

40


Dr. S. Blakey


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session 3: novel fuels - wordpress.com...04/04/2017 8 200 220 240 260 280 300 320 340 10 15 20 25...

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