Developing New Methods, Techniques to Improve Heavy-Duty Natural Gas Engine Performance By: Mehrzad Kaiadi Supervisor: Associate Prof. Per Tunestål GERG ACADEMIC NETWORK EVENT - 2010 Division of Combustion Engines, Dept. of Energy Sciences Lund University Sweden
Gas Engine @ Lund University Contents Background Objectives Experimental setup Results Conclusion Future Work 2
Background Gas Engine @ Lund University World Energy Consumption World CO2 Production Source: Energy Information Administration (EIA) 3
Background Gas Engine @ Lund University The main fuel in transporttation sector are Diesel & Gasoline Natural Gas is a good alternative fuel Availability Reliability of resources Costs Bridge to Hydrogen Society CH 4 + H 2 O --> CO + 3H 2 4
Background Gas Engine @ Lund University High octane number Cleaner fuel (mainly CH4) Gasoline Natural gas Source: SwRI Source: Heywood 5
Background Gas Engine @ Lund University Stoichiometric better choice Almost same performance Lower emissions (3-way CAT) 6
Objectives Gas Engine @ Lund University Lower Comp-Ratio Throttling losses Lower fuel density Lower Comp-Ratio Higher Exhaust-Temp Knock Narrow A/F window 7
Experimental Setup Gas Engine @ Lund University Number of Cylinder Displacement 6 9,4 Liter Bore 120 mm Stroke 138 mm Compression Ratio Ignition sequence Fuel 10,5:1 1-5-3-6-2-4 Natural Gas 8
Gas Engine @ Lund University New features Multi-Port fuel injection is designed (Single point injection is replaced) Why? Control fuel injection for each cylinder individually Rapid engine response to change throttle position Ion-Current measurments Flexible control system 9
Gas Engine @ Lund University Results High performance Model-based controllers to ensure the transient capability Hythane Improving Engine Efficiency at Part Loads Closed-loop dilution limit control Developing new method for calculating combustion stability Engine modifications to improve efficiency & Extend the Maximum load limit 10
EGR Reduces Throttling Losses SAE Paper#2008-01-1722 Throttle Air 1- Without EGR Same load Air EGR 2- With EGR Using optimum amount of EGR can minimize the losses 11
Calculation of COV(IMEP) SAE Paper#2008-01-1722 COV is a normalized standard deviation over large number of cycles Mean value changes during transients Replacing mean value by filtered IMEP to remove deterministic changes from COV IMEP ( k + 1) = λ IMEP ( k) + (1 λ ) IMEP ( k) filtered m filtered m net COV imep 2 ( IMEP net IMEP ) = N 100 ( IMEP ) λ Selected depending on expected time constants m 12
Calculation of COV(IMEP) SAE Paper#2008-01-1722 13
Control SAE Paper#2008-01-1722 14
Pumping Losses SAE Paper#2008-01-1722 Throttle Position [%] 44 42 40 38 36 34 32 30 PMEP [Bar] @ 1200 RPM Not tested data 25% PMEP decreases BMEP 2.5 bar BMEP 4 bar BMEP 5.5 bar 28 10 % Unstable PMEP region decreases 26 0 20 40 60 80 100 EGR Valve Position [%] 0.6 0.55 36% PMEP decreases 0.5 0.45 0.4 0.35 0.3 15
Fuel Consumption 45 SFC [g/kwh] @ 1200 RPM SAE Paper#2008-01-1722 320 Throttle Position [%] 40 35 30 Not tested data 4.5 % Lower fuel Consumption BMEP 2.5 bar BMEP 4 bar BMEP 5.5 bar Unstable region 25 0 20 40 60 80 EGR Valve Position [%] 300 280 5 % Lower fuel Consumption 5.9 % Lower fuel Consumption 260 240 16
Gas Engine @ Lund University Engine Modification New Piston design Higher compresion ratio Higher turbulence level New EGR Configuration Higher EGR rate Faster & more rebust control of EGR VGT Adjusting boost pressure Minimizing throttle losses 17
Improving Efficiency Gas Engine @ Lund University 28 26 Combustion Duration Vs. Engine Speed @ (WOT) Original Piston Quarttet Piston 0.48 Gross-Indicated Efficiency Vs. Engine Speed @ WOT Combustion Duration [CAD] 24 22 20 18 16 14 12 10 800 1000 1200 1400 1600 1800 Engine Speed [RPM] Gross-Indicated Efficiency [-] 0.46 0.44 0.42 0.4 0.38 Original Piston Quarttet Piston 800 1000 1200 1400 1600 1800 Engine Speed [RPM] 18
Extending the dilution limit Gas Engine @ Lund University COV [%] 70 60 50 40 30 Cyclic variation Vs. EGR rate / Original Piston Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Cylinder 5 Cylinder 6 COV [%] 80 70 60 50 40 30 Cyclic variation Vs. EGR rate / Quartette Piston Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Cylinder 5 Cylinder 6 20 20 10 10 0 0 5 10 15 20 EGR Rate [%] 0 0 5 10 15 20 25 30 EGR Rate [%] 19
Extending the load limit Gas Engine @ Lund University 20 19 Maximum Load Vs. Engine Speed @ (WOT) 18% higher load BMEP [Bar] 18 17 16 15 14 13 12 11 10 9 Original Piston Quarttet Piston Quarttet Piston & VGT 800 1000 1200 1400 1600 1800 Engine Speed [RPM] 20
Gas Engine @ Lund University Conclusions New methods & Techniques are developed to Improve efficiency @ all operation area Extend Maximum load limit by ~18% Ensure catalyst high efficiency 21
Gas Engine @ Lund University Future Work Minimizing throttling losses be means of VGT Lots of potentials by running on LNG Utilizing the Cold Energy 22
Contact information E-mail: Mehrzad.Kaiadi@energy.lth.se Phone: +46 46 222 79 00