Effects of Pilot Injection Strategies on Spray Visualization and Combustion in a Direct Injection Compression Ignition Engine using DME and Diesel

7 th Asian DME Conference 16-18 November, 2011 Toki Messe Niigata Convention Center, Niigata, Japan Effects of Pilot Injection Strategies on Spray Visualization and Combustion in a Direct Injection Compression Ignition Engine using DME and Diesel Jaehoon Jeong SeJun Lee Ocktaeck Lim University of Ulsan

Contents INTRODUCTION OBJECTIVES EXPERIMENTAL SETUP Spray Experimental System Engine Experiment System RESULTS Spray Experiment Engine Experiment CONCLUSION

DME Engine Characteristics Advantages Equal dynamic characteristic of diesel engine The Experimental Study of Emission Characteristics and Fuel Efficiency for the Heavy-Duty DME Bus, KSAE, submitted, 2011 Almost Smoke-less Combustion Improvement of Performance and Emission Gas Level of Dimethyl-Ether-Fueled Diesel Engine, JSAE, 2005 Improving the exhaust characteristic without after-treatment system Potential of Fuel Stratification for Reducing Pressure Rise Rate in HCCI Engines fueled with DME/n-Butane Good mixture formation & No wall wetting Disadvantages Low the fuel efficiency Development of a Heavy-Duty DME Truck in EFV21 Project~Research and Development of DME Engine and Chassis,SAE paper 2005-03-0176, 2005 Potential for high NOx emissions Development of NOx storage reduction system for a dimethyl ether engine,sae paper 2004-01-1832, 2004 Small low heating value compared to the diesel The Performance of a Diesel Engine for Light Duty Truck Using a Jerk Type, In-Line DME Injection System, SAE paper 2004-01-1862, 2004

DME Engine Characteristics Need more DME injection quantity : Due to small low heating value than diesel Enlargement of nozzle holes diameter : Mitsuru Konno, Kazuki Chiba, and Takeshi Okamoto, Experimental and Numerical Analysis of High Pressure DME Spray, SAE, 2010-01-0880, 2010 Smoke formation in CI engine - Inner boundary of diffusion flame : High temperature in combination with less available oxygen Using DME fuel for smoke reduction : H. Teng and G. Regner, Fuel Injection Strategy for Reducing NOx Emissions from Haevy-Duty Diesel Engines Fueled with DME, SAE 2006-01-3324, 2006 NOx formation in CI engine - Premixed combustion / Outer boundary of diffusion flame : Sudden combustion of over premixed fuel-air mixture with high temperature Applying Pilot Main injection strategy for NOx reduction : K. Okude, K. Mori, S. Shiino, K. Yamada and Y. Matsumoto, Effects of Multiple Injections on Diesel Emissions and Combustion Characteristics, SAE 2007-01-4178, 2007

Contents INTRODUCTION OBJECTIVES EXPERIMENTAL SETUP Spray Experimental System Engine Experiment System RESULTS Spray Experiment Engine Experiment CONCLUSION

Objectives Spray Experiment : To perform the spray experiments by the increase of nozzle hole diameter for solve DME`s small low heating value Parameter - Nozzle hole diameter Analysis - Injection quantity - Penetration lenth - BMEP - Spray angle Engine Experiment : To apply Pilot-Main injection strategy using DME for low NOx and high power in CI engine Parameter - Dwell time between main injection and pilot injection - Main injection timing retard Acquisition of Data - Cylinder Combustion Pressure - Torque - Exhaust Gas (CO,THC,NOx and Smoke) Analysis - Curve of Combustion Pressure - Heat Release Rate - Emissions Characteristic

Contents INTRODUCTION OBJECTIVES EXPERIMENTAL SETUP Spray Experimental System Engine Experiment System RESULTS Spray Experiment Engine Experiment CONCLUSION

Spray Experiment System Spray Visualization System N 2 DME Injection System Accumulator Cooling Fan DME D M E Chamber Low Pressure Pump Compressor Check Valve Refrigerant Compressor Air Pump Air Accumulator Relief Valve Return Line Common Rail PCV Driver Charge Amplifier Pressure Sensor Injector Common Rail Solenoid Injector Peak & Hold Driver Pulse Generator Injector Driver High Pressure Chamber Strobe Light Computer N2 Camera Fuel Quantity Measuring Device DME High Pressure Line DME Low Pressure Line Signal Line Air, N2 Line Fuel Quantity Measuring Device

Fuel Injection System Fuel Injection Systems for DME and Diesel DME Diesel Common-rail Injector The 2 nd generation of Common-rail (Bosch) Common-rail solenoid injector from (Bosch) Low pressure pump Pressurized by N 2 Vane-type pump High pressure pump Air driven liquid pump (Haskel) Radial piston pump (Bosch) Fuel outlet (Liquid) Piston Pressurization 15 bar Fuel inlet Vane Fuel outlet Fuel outlet Air drive inlet N 2 N 2 Fuel inlet DME Air drive outlet N 2 Fuel outlet Fuel inlet

Test injector VOC Type Production by Nozzle type Φ = 0.166 [ Diesel ] Delphi VCO The number of nozzle hole 6 Φ = 0.300 [ DME ] Diameter of nozzle hole [mm] 0.166 0.300 Spray angle [deg] 140

Dimethyl-Ether, DME Physical properties of DME and Diesel Property DME Diesel Chemical structure CH 3 OCH 3 C n H 1.8n Auto-ignition temperature [ ] 235 250 Oxygen content [wt %] 34.8 0 Boiling point [, 1atm] -25.1 180-370 Liquid density [kg/m 3, 20, 2MPa] 668 824 Vapor pressure [MPa, 20 ] 0.51 - Cetane number 55-60 40 55 Lower calorific value [MJ/Kg] 27.6 42.5 Adding Bio-diesel aobut 1% for lubrication

Contents INTRODUCTION OBJECTIVES EXPERIMENTAL SETUP Spray Experimental System Engine Experiment System RESULTS Spray Experiment Engine Experiment CONCLUSION

Research Engine Engine type Water-cooled 4 cycle diesel Number of cylinder 1 Bore Stroke 83 92 mm Displacement 498 cm 3 Number of valves 2 intake, 2 exhaust Compression ratio 19.5 Valve timing Intake Exhaust 8 o CA btdc / 44 o CA abdc 54.6 o CA btdc / 7.4 o CA atdc Fuel injection system Injection type Nozzle holes Nozzle hole diameter Common-rail Direct injection 7 holes 0.141mm

Schematic of Engine Facility To Stack Exhaust -Gas Analyzers (Horiba MEXA-7100 DEGR) CO HC NOx Exhaust plenum Smoke Meter (AVL 415 smoke meter) EC Dynamometer Intake Plenum Air Heater Laminar flow meter DP sensor Air filter Air in Engine Controller Encoder Interfacing Box Injector Driver Encoder Diesel Testing Common-rail Fuel Injection System for Diesel injection DME Testing Common-rail Fuel Injection System for DME injection Common-rail Pressure Control Driver

Contents INTRODUCTION OBJECTIVES EXPERIMENTAL SETUP Spray Experimental System Engine Experiment System RESULTS Spray Experiment Engine Experiment CONCLUSION

Experimental Condition of Spray Experimental Condition of Spray DME Diesel Injector diameter Φ = 0.300 mm Φ = 0.166 mm Injection pressure Ambient pressure Injection duration The number of injection 700 bar 55 bar 1ms 1000 times

Injection Quantity [kj/cycle] Injection Quantity [ml/cycle] Injection Quantity Injection Quantity DME, Φ = 0.300 mm Diesel, Φ = 0.166 mm P inject = 700 bar P o = 55 bar (by N 2 ) T o = 25 ± 1 Diesel_P amb 5.5MPa_0.166 mm DME_P amb 5.5MPa_0.300 mm 0.09 0.07 0.05 1.8 0.03 1.6 1.4 1.2 1 300 350 400 450 500 550 600 650 700 750 Injection Pressure[bar]

Spray Shape Diesel Spray Shape [Φ Injector = 0.166 mm] Fuel = Diesel Φ Injector = 0.166 mm P inject = 700 bar P o = 55 bar (by N 2 ) T o = 25 ± 1

Spray Shape DME Spray Shape [ΦInjector = 0.300 mm] Fuel = DME ΦInjector = 0.300 mm Pinject = 700 bar Po = 55 bar (by N2) To = 25 ± 1 Smart Powertrain Lab.

Spray Shape Diesel Spray Shape [ΦInjector = 0.166 mm] 0.1ms 0.4ms 0.7ms 1.0ms 1.3ms 1.6ms Fuel = Diesel ΦInjector = 0.166 mm Pinject = 700 bar Po = 55 bar (by N2) To = 25 ± 1 1.9ms 0.4ms 0.7ms 1.0ms 1.3ms 1.6ms 2.5ms Fuel = DME ΦInjector = 0.300 mm Pinject = 700 bar Po = 55 bar (by N2) To = 25 ± 1 DME Spray Shape [ΦInjector = 0.300 mm] 0.1ms 2.2ms 1.9ms 2.2ms 2.5ms Smart Powertrain Lab.

Penetration Spray Angle Length [degree] [mm] Spray Shape Spray Angle Length 80 70 60 50 40 30 20 10 0 P inject = 700 bar DME, Φ = 0.300 mm Diesel_0.166 P o = 55 mm_70 bar (by MPa N 2 ) Diesel, Φ = 0.166 DME_0.300 mm T o = 25 mm_70 ± 1 MPa 0 0.5 1 1.5 2 2.5 3 After Start of Injection [ms]

Contents INTRODUCTION OBJECTIVES EXPERIMENTAL SETUP Spray Experimental System Engine Experiment System RESULTS Spray Experiment Engine Experiment CONCLUSION

Operating Condition Operating Condition Engine speed 1200 rpm Intake air temperature 80 ±2 Coolant temperature 25 ±1 Fuel injection pressure Injection Test fuel 700 bar Pilot-Main injection DME (with biodiesel 1% for lubricity additive) Diesel

Injection Strategy Injection Quantity DME quantity Diesel quantity Input calories Single 46 mm 3 31 mm 3 1.31 kj/cycle 2-Stage Pilot Main 5.7 mm 3 (1/8) 40.3 mm 3 (7/8) 4 mm 3 (1/8) 27 mm 3 (7/8) 0.16 kj/cycle 1.15 kj/cycle

Injection Strategy Injection Timing Single 2-Stage dsoi 0 o CA Main -4, -2, 0, 2, 4 o CA atdc dsoi 10, 16, 22 o CA Main -4, -2, 0, 2, 4 o CA atdc 1.31 kj/cycle (8/8) 1.15 kj/cycle (7/8) 0.16 KJ/Cycle (1/8) dsoi : 0 o CA [ Single injection ] dsoi : 22 o CA 1.15 kj/cycle (7/8) 1.15 kj/cycle (7/8) 0.16 kj/cycle (1/8) 0.16 KJ/Cycle (1/8) dsoi : 16 o CA dsoi : 10 o CA

Combustion Characteristic Cylinder Pressure & HRR [ SOI main : -4 o CA atdc ] SOI main : -4 o CA atdc DME Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 kj/cycle Pilot-main Injection 1 Ignition delay : 6.6 o CA 1 1 Single Injection 1 Ignition delay : 8.8 o CA

Emission Characteristic BMEP / NOx Diesel dsoi: 10 o CA dsoi: 22 o CA dsoi: 16 o CA Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 kj/cycle DME Single injection

Emission Characteristic Smoke / NOx Diesel Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 kj/cycle DME

Emission Characteristic CO+THC / NOx Diesel Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 kj/cycle DME

Contents INTRODUCTION OBJECTIVES EXPERIMENTAL SETUP Spray Experiment Engine Experiment RESULTS Spray Experiment Engine Experiment CONCLUSION

Conclusion Spray Experiment Investigation of DME low heat value problem by increasing the nozzle holes diameter. spray of DME and diesel is roughly similar after 1ms Engine Experiment BMEP of pilot injection is increase than single injection. So, Pilot injection is more effective to increase the BMEP in DME injection than diesel injection. Lead to low NOx emissions due to the pilot injection Lower CO and THC emissions than diesel injection and DME combustion is smokeless

Thank you for listening.

APPENDIX

BMEP [kpa] BMEP Diesel injection VS Pilot-main injection 640 620 600 580 560 540 520 500 480 460 40 10 16 22 Dwell time between pilot & main injections [ o CA] Single injection SOI Main : -4 o CA atdc (Diesel) SOI Main : -4 o CA atdc (DME) SOI Main : -2 o CA atdc (Diesel) SOI Main : -2 o CA atdc (DME) SOI Main : 0 o CA atdc (Diesel) SOI Main : 0 o CA atdc (DME) SOI Main : 2 o CA atdc (Diesel) SOI Main : 2 o CA atdc (DME) SOI Main : 4 o CA atdc (Diesel) SOI Main : 4 o CA atdc (DME)

NOx [ppm] NOx Diesel injection VS Pilot-main injection 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 04 10 16 22 Dwell time between pilot & main injections [ o CA] Single injection SOI Main : -4 o CA atdc (Diesel) SOI Main : -4 o CA atdc (DME) SOI Main : -2 o CA atdc (Diesel) SOI Main : -2 o CA atdc (DME) SOI Main : 0 o CA atdc (Diesel) SOI Main : 0 o CA atdc (DME) SOI Main : 2 o CA atdc (Diesel) SOI Main : 2 o CA atdc (DME) SOI Main : 4 o CA atdc (Diesel) SOI Main : 4 o CA atdc (DME)

CO [ppm] CO Diesel injection VS Pilot-main injection 400 350 300 250 200 150 100 50 0 04 10 16 22 Dwell time between pilot & main injections [ o CA] Single injection SOI Main : -4 o CA atdc (Diesel) SOI Main : -4 o CA atdc (DME) SOI Main : -2 o CA atdc (Diesel) SOI Main : -2 o CA atdc (DME) SOI Main : 0 o CA atdc (Diesel) SOI Main : 0 o CA atdc (DME) SOI Main : 2 o CA atdc (Diesel) SOI Main : 2 o CA atdc (DME) SOI Main : 4 o CA atdc (Diesel) SOI Main : 4 o CA atdc (DME)

THC [ppm] THC Diesel injection VS Pilot-main injection 350 300 250 200 150 100 SOI Main : -4 o CA atdc (Diesel) SOI Main : -4 o CA atdc (DME) SOI Main : -2 o CA atdc (Diesel) SOI Main : -2 o CA atdc (DME) SOI Main : 0 o CA atdc (Diesel) SOI Main : 0 o CA atdc (DME) SOI Main : 2 o CA atdc (Diesel) SOI Main : 2 o CA atdc (DME) SOI Main : 4 o CA atdc (Diesel) SOI Main : 4 o CA atdc (DME) 50 0 04 10 16 22 Dwell time between pilot & main injections [ o CA] Single injection

Smoke Diesel injection VS Pilot-main injection Single injection 0

Heat-Release Rate [J/ o CA] Heat-Release Rate [J/ o CA] Heat-release rates (356 o CA) A comparison of heat-release rates in diesel & DME 180 150 120 90 60 30 0 Diesel DME - 4 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc] 180 150 120 90 60 30 0

Heat-Release Rate [J/ o CA] Heat-Release Rate [J/ o CA] Heat-release rates (358 o CA) A comparison of heat-release rates in diesel & DME 180 150 120 90 60 30 0 Diesel DME -2 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc] 180 150 120 90 60 30 0

Heat-Release Rate [J/ o CA] Heat-Release Rate [J/ o CA] Heat-release rates (360 o CA) A comparison of heat-release rates in diesel & DME 180 150 120 90 60 30 0 0 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA DME Diesel 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc] 180 150 120 90 60 30 0

Heat-Release Rate [J/ o CA] Heat-Release Rate [J/ o CA] Heat-release rates (362 o CA) A comparison of heat-release rates in diesel & DME 180 150 120 90 60 30 0 2 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA DME Diesel 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc] 180 150 120 90 60 30 0

Heat-Release Rate [J/ o CA] Heat-Release Rate [J/ o CA] Heat-release rates (364 o CA) A comparison of heat-release rates in diesel & DME 180 150 120 90 60 30 0 Diesel DME 4 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc] 180 150 120 90 60 30 0

Cylinder Pressure [bar] Cylinder Pressure [bar] Pressure traces (356 o CA) 100 90 80 70 60 50 40 30 20-4 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA Diesel DME 70 60 50 40 30 20 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc] 100 90 80

Cylinder Pressure [bar] Cylinder Pressure [bar] Pressure traces (358 o CA) 100 90 80 70 60 50 40 30 20-2 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA Diesel DME 70 60 50 40 30 20 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc] 100 90 80

Cylinder Pressure [bar] Cylinder Pressure [bar] Pressure traces (360 o CA) 100 90 80 70 60 50 40 30 20 0 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA Diesel DME 100 90 80 70 60 50 40 30 20 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc]

Cylinder Pressure [bar] Cylinder Pressure [bar] Pressure traces (362 o CA) 100 90 80 70 60 50 40 30 20 2 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA Diesel DME 90 80 70 60 50 40 30 20 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc]

Cylinder Pressure [bar] Cylinder Pressure [bar] Pressure traces (364 o CA) 100 90 80 70 60 50 40 30 20 4 o CA atdc dsoi: 0 o CA dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA DME Diesel 70 60 50 40 30 20 340 345 350 355 360 365 370 375 380 385 390 Crank Angle [ o CA atdc] 100 90 80

BMEP [kpa] Multiple injection Brake Mean Effective Pressure - BMEP 640 620 600 580 560 dsoi: 0 o CA (Diesel) dsoi: 0 o CA (DME) dsoi: 10 o CA (Diesel) dsoi: 10 o CA (DME) dsoi: 16 o CA (Diesel) dsoi: 16 o CA (DME) dsoi: 22 o CA (Diesel) dsoi: 22 o CA (DME) 540 520 500 480 460-4 -2 0 2 4 Start of Main Injection [ o CA]

THC [ppm] Multiple injection Total Hydro Carbon - THC 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0-4 -2 0 2 4 Start of Main Injection [ o CA] dsoi: 0 o CA (Diesel) dsoi: 0 o CA (DME) dsoi: 10 o CA (Diesel) dsoi: 10 o CA (DME) dsoi: 16 o CA (Diesel) dsoi: 16 o CA (DME) dsoi: 22 o CA (Diesel) dsoi: 22 o CA (DME)

CO [ppm] Multiple injection Carbon Monoxide - CO 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0-4 -2 0 2 4 Start of Main Injection [ o CA] dsoi: 0 o CA (Diesel) dsoi: 0 o CA (DME) dsoi: 10 o CA (Diesel) dsoi: 10 o CA (DME) dsoi: 16 o CA (Diesel) dsoi: 16 o CA (DME) dsoi: 22 o CA (Diesel) dsoi: 22 o CA (DME)

NOx [ppm] Multiple injection Nitrogen Oxides - NOx 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0-4 -2 0 2 4 Start of Main Injection [ o CA] dsoi: 0 o CA (Diesel) dsoi: 0 o CA (DME) dsoi: 10 o CA (Diesel) dsoi: 10 o CA (DME) dsoi: 16 o CA (Diesel) dsoi: 16 o CA (DME) dsoi: 22 o CA (Diesel) dsoi: 22 o CA (DME)

CO 2 [%] Multiple injection Carbon monoxides - CO 2 11 10.5 10 dsoi: 0 o CA (Diesel) dsoi: 0 o CA (DME) dsoi: 10 o CA (Diesel) dsoi: 10 o CA (DME) dsoi: 16 o CA (Diesel) dsoi: 16 o CA (DME) dsoi: 22 o CA (Diesel) dsoi: 22 o CA (DME) 9.5 9 8.5 8-4 -2 0 2 4 Start of Main Injection [ o CA]

th [-] Multiple injection Thermal efficiency - th 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25-4 -2 0 2 4 Start of Main Injection [ o CA] dsoi: 0 o CA (Diesel) dsoi: 0 o CA (DME) dsoi: 10 o CA (Diesel) dsoi: 10 o CA (DME) dsoi: 16 o CA (Diesel) dsoi: 16 o CA (DME) dsoi: 22 o CA (Diesel) dsoi: 22 o CA (DME)

CO & THC [ppm] NOx [ppm] Diesel & DME single injection Emissions: NOx, CO, THC NOx: Diesel NOx: DME CO : Diesel CO : DME THC: Diesel THC: DME 2000 1800 1600 1400 1200 1000 900 750 600 450 300 150 0-4 -2 0 2 4 Start of Main Injection [ o CA]

BMEP [kpa] Emission Characteristic BMEP / NOx 560 dsoi: 10 o CA 540 520 dsoi: 22 o CA dsoi: 16 o CA DME Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 kj/cycle 500 480 Single injection 460 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 NOx [ppm] SOI main :-4 o CA atdc SOI main :-2 o CA atdc SOI main : 0 o CA atdc SOI main : 2 o CA atdc SOI main : 4 o CA atdc CASE2 (SOI single&main :364 o CA, 16 o CA)

Injection Strategy Injection Quantity DME quantity Diesel quantity Input calories 1.31 KJ/Cycle Single 46 mm 3 31 mm 3 1.31 KJ/Cycle 2-Stage Pilot Main 5.7 mm 3 (1/8) 40.3 mm 3 (7/8) 4 mm 3 (1/8) 27 mm 3 (7/8) 0.16 KJ/Cycle 1.15 KJ/Cycle 0.16 KJ/Cycle 1.15 KJ/Cycle Injection timing dsoi Single 2-Stage dsoi 0 o CA Main -4, -2, 0, 2, 4 o CA atdc dsoi 10, 16, 22 o CA Main -4, -2, 0, 2, 4 o CA atdc

Timing Diagram for Synchronization High Pressure Chamber Computer Strobe Light Delayed time Delay [ms] 8~20μs Injector Camera 1ms Common Rail Solenoid Injector Peak & Hold Driver Pulse Generator Strobe Light Injection Trigger 1000ms Injector Driver Camera Shutter

Experimental Condition of Spray Injection quantity DME Diesel Injector diameter Φ = 0.300 mm Φ = 0.166 mm Injection pressure Ambient pressure Injection duration The number of injection Spray Shape [ length, angle ] 700 bar 55 bar 1ms 1000 times DME Diesel Injector diameter Φ = 0.300 mm Φ = 0.166 mm Injection pressure Ambient pressure Injection duration 700 bar 55 bar 1ms

분사젂략 파일럿분사적용 Fuel injection rate [mg/ o CA] dsoi 0 o CA 10 o CA 16 o CA 22 o CA SOI Main Injection dsoi SOI Pilot Injection o CA atdc o CA o CA atdc CASE 1 0 (Single injection) - 4-4 10-14 16-20 22-26 CASE 2 0 (Single injection) -2-2 10-12 16-18 22-24 CASE 3 0 (Single injection) -0 0 10-10 16-16 22-22 CASE 4 0 (Single injection) 2 2 10 8 16 14 22 20 CASE 5 0 (Single injection) 4 4 10 6 16 12 22 18

Multiple injection 다단분사 (Multiple injection): 연료를나누어서분사하는기술 < 출처 : Waseda Univ.> 파일럿분사 (Pilot injection): 예혼합연소에의한 PM 저감 젂분사 (Pre injection): 주분사의착화지연에의한 NOx, 진동및소음저감 주분사 (Main injection): 출력향상및소음저감 후분사 (After injection): 주연소의활성화로 PM 저감 포스트분사 (Post injection): 배기시스템에장착된촉매의활성화

APPENDIX

Diesel Injection System Radial-piston pump (Bosch)

DME Injection System

DME Injection System Return Red: High pressure pump Blue: Low pressure pump Dotting: Signal Check valve Commonrail Injector A B N 2 DME D M E Accumulator Accumulator Accumulator Air pump PCV driver Injector driver Engine controller Chamber Low pressure pump Regulator Compressor Relief valve Air driven liquid pump (Haskel) Encoder Encoder interfacing box Air

BMEP [kpa] Emission Characteristic NOx / BMEP 560 dsoi: 22 o CA DME 540 520 dsoi: 16 o CA Speed = 1200 rpm P injection = 700 bar Single injection P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle 500 480 dsoi: 10 o CA 460 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 NOx [ppm] SOI main :-4 o CA atdc SOI main :-2 o CA atdc SOI main : 0 o CA atdc SOI main : 2 o CA atdc SOI main : 4 o CA atdc

BMEP [kpa] Emission Characteristic NOx / BMEP 560 DME 540 520 dsoi: 10 o CA dsoi: 16 o CA dsoi: 22 o CA Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle 500 480 Single injection 460 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 NOx [ppm] SOI main :-4 o CA atdc SOI main :-2 o CA atdc SOI main : 0 o CA atdc SOI main : 2 o CA atdc SOI main : 4 o CA atdc

BMEP [kpa] Emission Characteristic NOx / BMEP 560 DME 540 520 dsoi: 16 o CA dsoi: 22 o CA dsoi: 10 o CA Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle 500 480 Single injection 460 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 NOx [ppm] SOI main :-4 o CA atdc SOI main :-2 o CA atdc SOI main : 0 o CA atdc SOI main : 2 o CA atdc SOI main : 4 o CA atdc

BMEP [kpa] Emission Characteristic NOx / BMEP 560 540 520 dsoi: 16 o CA 10 o CA dsoi: 22 o CA DME Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle 500 480 Single injection 460 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 NOx [ppm] SOI main :-4 o CA atdc SOI main :-2 o CA atdc SOI main : 0 o CA atdc SOI main : 2 o CA atdc SOI main : 4 o CA atdc

Emission Characteristic CO / THC DME Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle dsoi: 22 o CA 16 o CA Single injection 10 o CA

Emission Characteristic CO / THC DME Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle dsoi: 22 o CA Single injection dsoi: 10 o CA dsoi: 16 o CA

Emission Characteristic CO / THC DME Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle dsoi: 22 o CA dsoi: 10 o CA dsoi: 16 o CA Single injection

Emission Characteristic CO / THC DME Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle dsoi: 22 o CA dsoi: 16 o CA dsoi: 10 o CA Single injection

Emission Characteristic CO / THC DME Speed = 1200 rpm P injection = 700 bar P in,air = 1 bar T in,water = 80 ± 1 T in,air = 25 ± 2 Q in = 1.31 KJ/Cycle dsoi: 22 o CA Single injection 10 o CA dsoi: 16 o CA

THC [ppm] Emission Characteristic CO / THC 600 Lower CO and THC emissions than diesel injection 500 400 Diesel 300 DME injection DME DME Speed = 1200 rpm P T injection = 700 bar P in = 353.15 ± 2 K in,air = 1 bar PT in in,water = 0.1 = 80 MPa ± 1 PT injection in,air = 25700 ± 2 bar Q in = 1.31 KJ/Cycle 200 100 0 DME 0 100 200 300 400 500 600 CO [ppm]

NOx-Smoke trade-off NOx formation in CI engine - Premixed combustion / Outer boundary of diffusion flame : Sudden combustion of over premixed fuel-air mixture with high temperature Applying Pilot main injection strategy for NOx reduction : K. Okude, K. Mori, S. Shiino, K. Yamada and Y. Matsumoto, Effects of Multiple Injections on Diesel Emissions and Combustion Characteristics, SAE 2007-01-4178 Smoke formation in CI engine - Inner boundary of diffusion flame : High temperature in combination with less available oxygen Using DME fuel for smoke reduction : H. Teng and G. Regner, Fuel Injection Strategy for Reducing NOx Emissions from Haevy-Duty Diesel Engines Fueled with DME, SAE 2006-01-3324

DME Engine Characteristics Advantages Equal dynamic characteristic of diesel engine The Experimental Study of Emission Characteristics and Fuel Efficiency for the Heavy-Duty DME Bus, KSAE, submitted, 2011 Almost Smoke-less Combustion Improvement of Performance and Emission Gas Level of Dimethyl-Ether-Fueled Diesel Engine, JSAE, 2005 Improving the exhaust characteristic without after-treatment system Potential of Fuel Stratification for Reducing Pressure Rise Rate in HCCI Engines fueled with DME/n-Butane Good mixture formation & No wall wetting because of Low boiling point Disadvantages Low the fuel efficiency Development of a Heavy-Duty DME Truck in EFV21 Project~Research and Development of DME Engine and Chassis,SAE paper 2005-03-0176, 2005 Potential for high NOx emissions Development of NOx storage reduction system for a dimethyl ether engine,sae paper 2004-01-1832, 2004 Small low heating value compared to the diesel The Performance of a Diesel Engine for Light Duty Truck Using a Jerk Type, In-Line DME Injection System, SAE paper 2004-01-1862, 2004