Future fuels. by Bengt Johansson. Clean combustion research center KAUST

Future fuels by Bengt Johansson Clean combustion research center KAUST

Future fuels Energy Source Energy carrier Energy usage Well to Tank Tank to Wheel Well to Wheel 2

Conventional path Crude Oil η = 88% Ref. Gasoline η = 35% SI Mech. Energy Crude Oil η = 88% Ref. Diesel η = 45% Diesel Mech. Energy 3

Crude Oil Improve engine efficiency η = 88% Ref. Gasoline /Diesel η = 50% PPC Mech. Energy Crude Oil η = 88% Ref. Gasoline /Diesel η = 60% 8-stroke Mech. Energy 4

Crude Oil Improve fuel processing η = 88% Ref. Gasoline /Diesel η = 50% PPC Mech. Energy Crude Oil η = 94% Ref. Naphtha η = 50% PPC Mech. Energy 5

Biofuel with fermentation η = 30% η = 35% Biomass Ferm. Ethanol SI Mech. Energy 6

Biofuel with better ICE η = 30% η = 35% Biomass Ferm. Ethanol SI Mech. Energy η = 30% η = 43% Biomass Ferm. Ethanol CI Mech. Energy 7

Scania CI 8

Scania CI 9

Scania CI 10

Biomass Biofuel with better ICE η = 30% η = 35% Ferm. Ethanol SI Mech. Energy η = 30% η = 43% Biomass Ferm. Ethanol CI Mech. Energy η = 30% η = 50% Biomass Ferm. Ethanol PPC Mech. Energy 11

Experimental Investigation on Different Injection Strategies for Ethanol Partially Premixed Combustion SAE 2013-01-0281 Mehrzad Kaiadi, Bengt Johansson, Marcus Lundgren Lund University John A. Gaynor Scania CV AB

Biomass Conversion via Syngas Biomass η = 68% η = 50% Methanol PPC Mech. Energy 13

Methanol PPC 14

Natural gas Methanol = Liquid methane η = 70 78% η = 68% η = 50% Biomass Methanol PPC Mech. Energy 15

Methanol cost less than LNG 17

Methanol cost less than LNG 18

Natural gas η = 78% Electrofuel η = 68% η = 50% Biomass Methanol PPC Mech. Energy Electricity η = ~70 80% 19

Electrofuels, really? η = 50% Methanol PPC Mech. Energy Electricity η = ~70 80% η = ~98% 20

With 100% renewable electricity IF wind power should be sufficient also with low wind, we need much more power than average (1/capacity factor) and hence most of the time we have a surplus of energy. Use this surplus elctricityto make fuel (energy storage) 21 Wikipedia: Capacity factor

Example of How to Produce Electrofuels, Maria Grahn, Chalmers Water (H 2 O) Power Electrolysis Hydrogen (H 2 ) CO 2 from air and seawater H 2 CO 2 from combustion Denmark already had periods with negative price on electricity Electrofuels Sabatier reactor CO 2 Methane (CH 4 ) Methanol (CH 3 OH) DME (CH 3 OCH 3 ) Ethanol (C 2 H 5 OH) Biofuel production Biofuels Biomass (C 6 H 10 O 5 ) All biofuel production generates waste CO 2

Tank-Wheel study Review and Benchmarking of Alternative Fuels in Conventional and Advanced Engine Concepts To be published in SAE 2016-01-0882 by Martin Tuner, Lund University 23

SAE 2016-01- 0882 24

Towards 60% efficient IC engine by Bengt Johansson Clean combustion research center KAUST

What is a high efficiency? Any text book on ICE: Ideal cycle with heat addition at constant volume: With a compression ratio of 60:1 and γ=1.4 we get an efficiency of 80,6% Why then do engines of today have an efficiency of 20-40%??? 26

Outline What is high efficiency? Combustion, thermodynamic, gas exchange and mechanical efficiencies. All four must be high. Combustion to enable high efficiency HCCI Partially Premixed Combustion Can we do something about engine design? Conclusions

Energy flow in an IC engine η Brake = η Combustion * η Thermodynamic * η GasExchange * η Mechanical FuelMEP Combustion efficiency QemisMEP QhrMEP QhtMEP Thermodynamic efficiency QlossMEP Gross Indicated efficiency IMEPgross QexhMEP Gas exchange efficiency PMEP Net Indicated efficiency lmepnet Mechanical efficiency FMEP Brake efficiency BMEP

HCCI -Thermodynamic efficiency Saab SVC variable compression ratio, VCR, HCCI, Rc=10:1-30:1; General Motors L850 World engine, HCCI, Rc=18:1, SI, Rc=18:1, SI, Rc=9.5:1 Scania D12 Heavy duty diesel engine, HCCI, Rc=18:1; Fuel: US regular Gasoline SAE2006-01-0205 30

All four efficiencies 31 SAE keynote Kyoto 2007

Net indicated efficiency= η C η T η GE +100% SI std SI high HCCI VCR Scania

Brake efficiency SI std SI high HCCI VCR Scania

Net indicated efficiency= η C η T η GE 47% SI std SI high HCCI VCR Scania

PPC - Diesel engine running on gasoline HCCI: η i =47% => PPC: η i =57% 60 Group 3, 1300 [rpm] 55 Gross Indicated Efficiency [%] 50 45 40 35 30 25 FR47333CVX FR47334CVX FR47336CVX 20 0 2 4 6 8 10 12 14 Gross IMEP [bar] 36

Partially Premixed Combustion, PPC 6000 1200 HCCI CI 5000 4000 PPC 1000 800 HC [ppm] 3000 2000 600 400 NOx [ppm] 1000 200-180 -160-140 -120-100 -80-60 -40-20 SOI [ATDC] Def: region between truly homogeneous combustion, HCCI, and diffusion controlled combustion, diesel SAE 2004-01-2990 37

PPC: Effect of EGR with diesel fuel Load 8 bar IMEP Abs. Inlet Pressure 2.5 bar Engine Speed 1090 rpm Swirl Ratio 1.7 Compression Ratio 12.4:1 (Low) Scania D12 single cylinder DEER2005 and SAE 2006-01-3412 38

1 2 3 4

PPC with low cetane diesel Lic. Thesis by Henrik Nordgren 2005 and presented at DEER2005 40

Efficiencies 17.1:1 100 95 90 85 [%] 80 75 70 65 60 55 Combustion Efficiency Thermal Efficiency Gas Exchange Efficiency Mechanical Efficiency 50 4 5 6 7 8 9 10 11 12 13 Gross IMEP [bar] 41 SAE 2009-01-2668

Efficiencies 14.3:1 [%] 100 95 90 85 80 75 70 65 60 55 Combustion Efficiency Thermal Efficiency Gas Exchange Efficiency Mechanical Efficiency 50 4 6 8 10 12 14 16 18 Gross IMEP [bar] 42 SAE 2010-01-0871

Emissions NOx [g/kwh] 0.6 0.5 0.4 0.3 0.2 0.1 Gross Net Brake EU VI US 10 Smoke [FSN] 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 2 4 6 8 10 12 14 16 18 Gross IMEP [bar] 0 4 6 8 10 12 14 16 18 Gross IMEP [bar] 1.5 10 HC [g/kwh] 1.2 0.9 0.6 Gross Net Brake EU VI US 10 CO [g/kwh] 9 8 7 6 5 4 Gross Net Brake EU VI US 10 3 0.3 2 0 2 4 6 8 10 12 14 16 18 Gross IMEP [bar] 43 1 0 2 4 6 8 10 12 14 16 18 Gross IMEP [bar] 43

Emissions different fuels NOx [g/kwh] 0.5 0.45 0.4 0.35 0.3 0.25 0.2 Ethanol FR47330CVX FR47331CVX FR47333CVX FR47334CVX FR47335CVX FR47336CVX FR47338CVX Soot [FSN] 2.5 2 1.5 1 Ethanol FR47330CVX FR47331CVX FR47333CVX FR47334CVX FR47335CVX FR47336CVX FR47338CVX 0.15 0.1 0.5 0.05 0 2 4 6 8 10 12 14 16 18 20 Gross IMEP [bar] 0 2 4 6 8 10 12 14 16 18 20 Gross IMEP [bar] CO [g/kwh] 12 10 8 6 4 Ethanol FR47330CVX FR47331CVX FR47333CVX FR47334CVX FR47335CVX FR47336CVX FR47338CVX HC [g/kwh] 10 9 8 7 6 5 4 3 Ethanol FR47330CVX FR47331CVX FR47333CVX FR47334CVX FR47335CVX FR47336CVX FR47338CVX SAE 2010-01-0871 2 0 2 4 6 8 10 12 14 16 18 20 Gross IMEP [bar] 2 1 0 2 4 6 8 10 12 14 16 18 20 Gross IMEP [bar] 44

Experimental Apparatus, Scania D13 XPI Common Rail Orifices 8 [-] Orifice Diameter 0.19 [mm] Umbrella Angle 148 [deg] Engine / Dyno Spec BMEPmax 25 [bar] Vd 2124 [cm3] Swirl ratio 2.095 [-] SAE 2010-01-2198 45 Standard piston bowl, rc: 17.3:1 45

Tested Load Area Stable operational load vs. fuel type 25 20 IMEP gross [bar] 15 10 5 0 20 30 40 50 60 70 80 90 100 RON [-] 46

Efficiency with Diesel or Gasoline Average improvement of 16.6% points at high load by replacing diesel fuel with gasoline! 52 50 48 D13 Gasoline D13 Diesel Brake Efficiency [%] 46 44 42 40 38 36 34 5 10 15 20 25 30 Gross IMEP [bar] 47

Gross Indicated Efficiency 58 Gross Indicated Efficiency [%] 56 54 52 50 48 FR47338CVX FR47335CVX FR47334CVX 10%! 46 SAE paper 2010-01-1471 44 1.5 2 2.5 3 3.5 Abs Inlet Pressure [bar]

High efficiency thermodynamics: Simulation results from GT-power Indicated efficiency 65,2% Brake efficiency 60.5%

Any text book on ICE: Is 65% possible? Ideal cycle with heat addition at constant volume: With a compression ratio of 60:1 and γ=1.4 we get an efficiency of 80,6% 51

There are a few drawbacks Peak cylinder pressure [bar] 1000 900 800 700 600 500 400 300 200 100 Peak cylinder pressure as function of compression ratio Lambda = 1.2 Lambda = 3.0 Engine structure must be very robust (if at all possible) Very high friction and hence lower mechanical efficiency 0 0 10 20 30 40 50 60 70 Compression ratio 52

There are a few drawbacks 90 80 Thermodynamic efficiency as function of compression ratio No heat transfer losses With heat transfer losses (Woschni) Thermodynamic efficiency [%] 70 60 50 40 30 20 0 10 20 30 40 50 60 70 Compression ratio 53

How then make 60:1 usable? Swedish proverb: Den late förtar sig hellre än går två gånger Which according to google translate means: The lazy man rather breaks his back than walk twice 54

How about Take it in steps! 60 = 7. 75 If we divide the compression in two equal stages the total pressure (and temperature) ratio will be the product of the two 7.75:1 x 7.75:1=60:1 With a peak pressure of 300 bar the pressure expansion ratio is 300:1 and hence 300^(1/1.4)=58.8.1 in volume ratio (gamma=1.25 during expansion gives 96:1) 55

Split cycles from the past 56

From history: Compound Engine Divide the expansion in three cylinders with same force, F, on each piston. The smaller cylinder has higher pressure but also smaller area F=p*A 57

Split cycles from the present 59

Three step compression in production To run a smaller engine at higher load turbocharging is used. The engine is using two or three shafts of which only one can generate power High BMEP (up to 30 bar) results with two-stage turbo Peak pressure 200 bar F. Steinparzer, W. Stütz, H. Kratochwill, W. Mattes: Der neue BMW-Sechzylinder-Dieselmotor mit Stufenaufladung, MTZ, 5,2005 60

Divide the process into two cylinders Low pressure cycle Use large naturally aspirated engine designed for 30 bar peak pressure Load range 0-5 bar BMEP Peak pressure during the cycle 30 bar High pressure cycle Use small engine with 300 bar peak pressure feed by the large engine Load range 35-80 bar BMEP Peak pressure during the cycle 250-300 bar Friction FMEP 0.05-0.1 bar Friction FMEP 1.2-2.2 bar 61

Principle layout 4 stroke + 4 stroke 62

Operating cycle 4 + 4 stroke Pressure Combustion TDC Inlet 1 Compression Compression BDC Expansion Expansion TDC Exhaust Exhaust BDC 4 Inlet TDC 4 1 BDC TDC BDC TDC Exhaust 2 Inlet Compression Expansion 2 BDC TDC BDC TDC 3 3 Expansion Exhaust Inlet Compression TDC BDC TDC BDC TDC 63

DOUBLE COMPRESSION EXPANSION ENGINE CONCEPTS: A PATH TO HIGH EFFICIENCY Nhut Lam, Martin Tunér, Per Tunestål, Bengt Johansson, Lund University Arne Andersson, Staffan Lundgren, Volvo Group SAE 2015-01-1260

Conceptual design 4-4 SAE 2015-01-1260 65

Simulation study - Inputs DCEE=Double Compression Expansion Engine Simulation model DCEE DCEE Conv, Conv. Lambda, λ 1.2 3.0 1.2 3.0 Bore, HP-cylinder [mm] 95 95 317 249 Stroke, HP-cylinder [mm] 100 100 100 100 HP-displacement [dm^3] 0.71 0.71 7.9 4.9 Compr. ratio, HP-cylinder [-] 11.5 11.5 55 55 Bore, LP-cylinder [mm] 317 249 - - Stroke, LP-cylinder [mm] 100 100 - - LP-displacement [dm^3] 7.9 4.9 - - Charge air cooler temp (K) 350 - - - SAE 2015-01-1260 66

High Pressure cylinder SAE 2015-01-1260 67

Low Pressure cylinder SAE 2015-01-1260 68

Combined SAE 2015-01-1260 69

Heat Transfer!"!" = h!!!(!!!! )! To reduce heat transfer: Reduce heat transfer coeff., h Reduce surface area, A Reduce gas temperature Increase wall temperature 70

Wall surface area 0.35 Wall surface area as function of cylinder volume 0.3 0.25 Area [m 2 ] 0.2 0.15 0.1 0.05 SAE 2015-01-1260 0 0 1 2 3 4 5 6 7 8 9 Cylinder volume [dm 3 ] DCEE, lambda 1.2 DCEE, lambda 3.0 CI, lambda 1.2 CI, lambda 3.0 71

Area/volume-ratio 1200 1000 Wall surface area per volume as function of cylinder volume DCEE, lambda 1.2 DCEE, lambda 3.0 CI, lambda 1.2 CI, lambda 3.0 Area/Volume [m 2 /m 3 ] 800 600 400 200 0 0 1 2 3 4 5 6 7 8 9 SAE 2015-01-1260 Cylinder volume [dm 3 ] 72

Heat transfer losses 73

Estimation of friction mean effective pressure, FMEP 1.8 1.6 1.4 Friction is assumed to scale with Peak Cylinder Pressure, P max FMEP assumed to be 1.2 bar @200 bar P max HP cylinder, DCEE-concept FMEP [bar] 1.2 1 0.8 0.6 LP cylinder, DCEE-concept Traditional heavy duty turbocharged CI engine 0.4 0.2 Naturally aspirated SIengine @ 2300 rpm SAE 2015-01-1260 0 0 50 100 150 200 250 300 Designed engine peak cylinder pressure 74

Mechanical losses Unit DCEE, λ=1.2 DCEE, λ=3.0 Conventional, λ=1.2 Conventional, λ=3.0 Peak cylinder pressure -LP cylinder bar 36 16 -HP cylinder bar 300 FMEP -LP cylinder bar 0.21 0.09 -HP cylinder bar 1.8 Total FMEP bar 0.34 0.31 1.8 Net indicated work, IMEP n bar 8.8 4.3 12.9 6.3 Mechanical efficiency % 96.1 92.8 86.0 71.6 SAE 2015-01-1260 75

Resulting Efficiencies SAE 2015-01-1260 76

Summary HCCI has shown high efficiency Up to 100% improvement in indicated efficiency vs. standard SI combustion Modest combustion efficiency HCCI peaks at 47% indicated efficiency at around 6 bar BMEP PPC has shown higher fuel efficiency Indicated efficiency of 57% at 8 bar IMEP Indicated efficiency of 55% from 5-18 bar IMEP With 70 RON fuel we can operate all the way from idle to 26 bar IMEP With an effective compression/expansion ratio of 60:1 the split cycle concept shows 62% indicated/ 56% brake efficiency potential η T =1 1 R c γ 1 77

High Efficiency Combustion Engines What is the limit? It all starts at 40 and ends at 60 (% engine efficiency that is, not life) Prof. Bengt Johansson CCRC KAUST

Thank you! 79

Future fuels by Bengt Johansson Clean combustion research center KAUST