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Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
Experimental and numerical work at Ghent University on methanol combustion in SI engines Prof. Sebastian Verhelst Ghent University
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WHY METHANOL?
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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UGent ICE research focus: background
Starts from a vision on long term energy supply and energy carrier for transportation • Long term energy supply: selection of candidates based on
‣ Sustainability, of energy source and of harvesting
technology (includes e.g. recyclability)
‣ Scalability, i.e. abundance of energy source, and of resources needed for building the harvesting technology
• Conclusion: CSP (concentrated solar power) best choice
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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UGent ICE research focus: background
• Long term solution for transport? Options for energy carrier and powertrain?
‣ Sustainability: closed cycle for energy carrier and
powertrain materials
‣ Scalability: resources for energy carrier and powertrain
‣ Compact: need sufficient energy & power density
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Conclusions for sustainable transportation
• Energy carrier: need for renewable (solar), liquid fuels ‣ Efficient, so practical and cheap distribution and storage
• Powertrain: internal combustion engine ‣ Cheap to produce:
‧ Easy to produce ‧ From abundantly available, recyclable materials ‧ Relatively little energy needed for production
‣ Fuel flexible ‣ High power density ‣ Still potential for efficiency improvement
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Candidate fuels
• Simple molecules are preferred ‣ Production is more efficient ‣ Conversion (end-use) can be controlled more easily (η, emissions)
• Abundantly available building blocks: C, H, O, N, …
• Thus, most simple fuels: ‣ Hydrogen, H2 (at patm, liquid at 20K) ‣ Methane, CH4 (at patm, liquid at 91K) ‣ Ammonia, NH3 (at Tatm, liquid at 8.6 bar) ‣ Methanol, CH3OH (liquid) ‣ Dimethylether (DME), CH3OCH3 (liquid at 5.3 bar) ‣ …
LIQUIDS
6 Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
Case: methanol
• Can be produced in different ways ‣ Biomass, fossil fuels, synthesize using renewable energy
• Liquid ‣ Cheap tanks, cheap distribution ‣ Miscible with gasoline and ethanol ‣ Evolution of infrastructure possible
• High engine efficiencies possible ‣ High octane number, heat of vaporization, …
• Also building block for synthetic hydrocarbons (MTO) Has been a focus for UGent since 2009
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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UGent work on methanol as an engine fuel
PhD Jeroen Vancoillie 2009-2013 [1] • Problem statement: no simulation tools for engines
operating on light alcohols (MeOH/EtOH) ‣ Complexity of engines – optim. solely relying on expts. undoable ‣ Unique fuel properties – tools optimized for gasoline etc. ‣ Special working conditions – e.g. EGR%, charging pressures, …
• Contents ‣ Conversion of engine test benches, measurement database ‣ Fundamental data: laminar burning velocity, autoignition delays ‣ Evaluation of turbulent combustion velocity models ‣ Engine cycle simulations, normal + knocking operation
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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UGent work on methanol, cont.
MSc theses, postdoc stay • Extension of measurement database (incl. effects H2O) • Vehicle calculations PhD Louis Sileghem 2011-2015 [2] • Problem statement: introduction of methanol through use
as blend component (cfr. presentation James Turner, Univ. Bath); no simulation tools for engines on alcohol blends ‣ Non-linear behaviour burning velocity, knocking behaviour, …
• Contents: measurements; blending/mixing rules for burning velocities, auto-ignition delays; engine simulations
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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EXPERIMENTAL WORK Engine tests
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Properties MeOH ↔ gasoline & implications
Properties: • High heat of vaporization
• High octane number
• High flame speed
Potential • Even for gasoline-optimized
engine max. achievable engine load higher when using alcohols
• Increase in volumetric eff. due to high degree of charge cooling • Spark timing less knock limited due to elevated knock resistance and higher flame speeds
• Options for dedicated engines: • High compression ratio • High EGR ratios • Lean operation
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
Methanol Gasoline
325 1100
(kJ/kg)
95 109
RON
30 45
Laminar burning velocity at NTP (cm/s)
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Experimental work: flex-fuel
2 converted ( “flex-fuel”) PFI engines [3,4] • With same operating strategy:
‣ Relative efficiency benefits MeOH vs. gasoline order of 10% ‧ More isochoric combustion ‧ Less flow, cooling and dissociation losses
‣ Reductions of engine-out NOx levels of 5–10 g/kWh ‧ Lower combustion temperatures
• Alternative load control strategies ‣ WOT, lean; or WOT+EGR: relative eff. benefits of 5% vs. throttling ‣ Possible due to higher dilution tolerance of MeOH ‣ Also lower NOx, due to further lowering of combustion temperatures
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Experimental work: dedicated methanol [3,4]
VW TDI, CR 19.5:1 • Replaced diesel injectors with spark plugs,
mounted methanol PFI system • Reproduced EPA work (Brusstar et al.)
and expanded to lower loads • Faster, more stable combustion
‣ High CR, turbocharged, high turbulence ‣ More dilution tolerance ‣ Wider range (down to 3 bar BMEP)
• Lower in-cylinder temperatures ‣ Cooling & dissociation losses ↓ ‣ Knock/pre-ignition ↓; Engine-out NOx ↓
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Experimental work: dedicated methanol [3,4]
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
NOx (ppm)
BTE (%)
Unstable combustion CoV > 10% (EGR≈50 m%)
42%
Diesel-like peak BTE Part load efficiency gains up to 20% (compared to throttled operation)
Vast engine-out NOx reductions (ppm)
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Experimental work: dedicated methanol
• Dedicated engines: diesel-like efficiencies while using cheap aftertreatment systems
• Used engine bench results in vehicle driving cycle calculations [5]
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
26.5 25.6
31.8 31.3
22.0
24.0
26.0
28.0
30.0
32.0
34.0
NEDC FTP75
Effic
ienc
y %
Vehicle 5, MeOH, Throttle Vehicle 6, MeOH, WOT_EGR
1.19
2.20
0.10 0.11
0.00
0.50
1.00
1.50
2.00
2.50
NEDC NOx g/km FTP75 NOx g/mi
NO
x em
issi
ons
Vehicle 5, MeOH, Throttle Vehicle 6, MeOH, WOT_EGR
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Experimental work: DI engines
• Naturally asp. DI: Hyundai 2.4L at Argonne Nat. Lab [11] ‣ Tested MeOH vs. gasoline, EtOH, BuOH, E85, M56 ‣ Stock ECU – load limitations
(~injection duration; λ=1) ‣ Low-mid load: 2.7 %pt BTE increase
on MeOH vs. gasoline ‣ High load: 5.6 %pt (BTE=40%, i.e. -20% CO2)
• Turbocharged DI: Volvo 1.6L “T3” ‣ MoTeC M1 ECU ‣ In progress…
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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FUNDAMENTAL WORK Burning velocity measurements and computations
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Building blocks for engine cycle simulations
• Laminar burning velocity ul ‣ Groups chemical effects on combustion ‣ Function of pressure, temperature, mixture composition ‣ 50% higher than for gasoline faster combustion, higher efficiency
• Lack of reliable ul data for methanol at engine-like conditions ‣ Calculated ul using carefully selected chemical kinetics scheme ‣ Built correlation for use in engine code [6] ‣ Validated correlation
‧ Flat flame burner at Lund University [7] ‧ Spherical flames at Leeds University [1]
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Evaluation of ul correlation + ut models [8]
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Building blocks for engine cycle simulations, cont.
• Autoignition delay time τ ‣ Determines resistance to engine knock ‣ Function of pressure, temperature, mixture comp. ‣ RON 109 higher efficiency: either through
increased CR or wider use of MBT • Again, lack of data
‣ Calculated τ using the same chemical kinetics scheme as for ul
‣ Built correlation for use in engine code [9]
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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NUMERICAL WORK ul & τ correlations; engine simulation framework
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Multizone thermodynamic engine model
i.e. “quasi-dimensional” approach • Compromise between accuracy and computational effort • Framework for testing ul & τ correlations
‣ Power cycle: in-house GUEST code (Ghent University Engine Simulation Tool)
‣ Gas dynamics: GT-Power • Findings [10]
‣ “Puddling” model necessary: low volatility ‧ Evaporated fraction low compression slope underestimated ‧ Evaporated fraction high volumetric efficiency overestimated
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Engine cycle simulations
• Evaluation of ul&τ correlations, and ut models, against experimental database obtained on 2 engines with variation of: ‣ throttle position ‣ fuel-air equivalence ratio ‣ spark timing ‣ engine speed ‣ …
• Normal & knocking combustion [10] ‣ knocking: puddling model & in-cylinder
heat transfer to be revisited
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Summary
• UGent contributions on methanol-fueled ICEs ‣ Measurement database on a range of SI engines ‣ Correlations for ul, δl, τ for use in engine simulation ‣ Validation of engine cycle simulations against expt. database
• To be improved ‣ In-cylinder heat transfer models (work in progress at UGent) ‣ Proper modeling of evaporative cooling
• In progress or starting ‣ MeOH in downsized engine ‣ Dual-fuel operation: MeOH in diesel engine
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Outlook
LEANShips: Low Energy And Near to zero emissions Ships • EU Horizon 2020 Mobility for Growth ‘innovation action’ • 48 partners, 8 demonstrator platforms • UGent: WP05 leader “Demonstrating the potential of
methanol as an alternative fuel” (6 partners) ‣ Conversion of high speed marine diesel engine to dual fuel
operation with methanol ‣ LCA of methanol in shipping ‣ Tools for dissemination and market uptake (pilots)
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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References
1. Jeroen Vancoillie, Modeling the combustion of light alcohols in spark-ignition engines, PhD Ghent University, 2013 - download link
2. Louis Sileghem, Modeling the combustion of alcohol blends in SI engines, Ghent University, PhD defense July 2015
3. Vancoillie J et al, Experimental evaluation of lean-burn and EGR as load control strategies for methanol engine, SAE 2012-01-1283
4. Vancoillie J et al, The Potential Of Methanol As A Fuel For Flex-Fuel And Dedicated Spark-Ignition Engines, Applied Energy 102:140-149, 2013
5. Naganuma K et al, Drive Cycle Analysis of Load Control Strategies for Methanol Fuelled ICE Vehicle, SAE 2012-01-1606
6. Vancoillie J et al, Laminar burning velocity correlations for methanol-air and ethanol-air mixtures valid at SI engine conditions, SAE 2011-01-0846
7. Vancoillie J et al, The temperature dependence of the laminar burning velocity of methanol flames, Energy&Fuels 26:1557-1564, 2012
8. Vancoillie J et al, The turbulent burning velocity of methanol-air mixtures, Fuel 130:76-91, 2014
9. Vancoillie J et al, Development and Validation of A Knock Prediction Model for Methanol-Fuelled SI Engines, SAE 2013-01-1312
10. Vancoillie J et al, Development and validation of a quasi-dimensional model for methanol and ethanol fueled SI engines, Applied Energy 132:412-425, 2014
11. Sileghem L et al, Experimental investigation of a DISI production engine fuelled with methanol, ethanol, butanol and iso-stoichiometric alcohol blends, SAE 2015-01-0768
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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Thank you for your attention!
Sebastian Verhelst [email protected] http://users.ugent.be/~sverhels
Methanol workshop, Lund – March 17th 2015 Faculty of Engineering and Architecture – Department of Flow, Heat and Combustion Mechanics
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