1. 1 PM REMOVAL SYSTEM FOR DIESEL PASSENGER VEHICLE USING NON-THERMAL PLASMA Kazuhiko Madokoro, Y. H. Kim, K. Naito, T. Ogawa H. Fujikawa, K. Hasegawa, H. Tanaka Research Institute of Innovative Technology for the Earth (RITE), Japan S. Yamamoto, S. Kodama, C. Mine S. Yao, Y. Fujioka Daihatsu Motor Co., Ltd., Japan S. Soma, T. Nakajima, G. Sugiyama Japan Automobile Research Institute (JARI), Japan

2. 2  Introduction - Diesel emission regulations - What is plasma? - Advantages and problems of plasma technology  Experimental  Results  Conclusion Outline

3. 3 Diesel emission regulations (Passenger vehicles) US EU Japan 0.14 0.4 0.28 0.052 0.013 1997 2002 2005 2009 PM [g/km] 0.080 0.005 0.08 NOx [g/km] 11, 10 ･ 15, JC08 mode Our target 0.05 0.025 0.005 0.50.180.25 2005 Euro4 2000 Euro3 1994 Tier1 2004 ～ 06 Tier2 (Bin#9) 2007 Tier2 (Bin#5) 0.062 0.037 0.006 0.0440.780.19 2009 Euro5 NEDC modeFTP mode NOx [g/km]  Stricter regulations for emission control are being set all over the world.  The Japanese post new long-term emission regulation comes into force.  A newly established emission test mode (JC08) has also been introduced. Japanese JC08 mode

4. 4  Plasma is called a "Fourth State of Matter".  Plasma is a partially ionized gas mixture and contains electrons, ions, neutral atoms, molecules, reactive free radicals and photons. LiquidGas MeltingEvaporation Plasma Electrolytic dissociation Solid Fourth stateThree states of matter Exhaust gases O 2, NO, H 2 O etc O 3, O, NO 2 etc Discharge plasma PM It is generally known that highly reactive species such as O 3, O, NO 2 and OH are generated in the plasma of diesel exhaust gases. These reactive species can lead to oxidation of PM. CO 2 CO Application of the plasma to diesel exhaust gases LightningAurora What is Plasma ?

5. 5   Successive PM removal irrespective of ambient temperature   No using Platinum-Group Metals   Easily controllable of PM removal rates by power management   Simple reactor configuration for low pressure drop  Designing of a novel plasma reactor   Reduction of energy consumption   Improvement of power supply system & power delivery for plasma generation   Elucidation of PM removal mechanism   Durability of the system  Advantages  Hurdles to overcome before practical use Advantages and problems of plasma technology PM emission : below 0.005 g/km PM emission : below 0.005 g/km Pressure drop: below 5 kPa Pressure drop: below 5 kPa Fuel penalty : below 2.5% (at Japanese JC08 mode) Fuel penalty : below 2.5% (at Japanese JC08 mode) Target

6. 6  Introduction  Experimental - Discharge system - Emission measurement system - Modal emission test  Results  Conclusion Outline

7. 7 Discharge system Oscilloscope AC 100V Plasma Reactor High voltage probe Current Transformer Pulse Power Supply DC Power Supply Dielectric barrier discharge reactor driven by high-voltage pulses Discharge Ref: S. Yao (RITE), AIChE J., Vol. 53, 1891-1897 (2007)

8. 8 Non-thermal plasma reactor Dielectric plateElectrode High voltage Earth Dielectric (General flat plate of alumina) Electrode Gas flow CO 2 (CO) Temporary trap Oxidation (Combustion) PM (c) Gas flow

9. 9 Dilution Air Sampling bag PM filter CFV-CVS Engine Exhaust Particulate Sizer (EEPS-3090) Full flow dilution tunnel Emission measurement system Dilutor Chassis dynamometer Particle number concentration PM mass emission Engine1.5 L 4-cycle diesel engine Original Emission levelEuro4 Original aftertreatmentDiesel oxidation catalyst (DOC) Vehicle data Vehicle emission measurement was carried out at JARI. Soluble organic fraction (SOF) Insoluble organic fraction (ISF) Soxhlet extraction

10. 10 Warm-up period Cold mode start (without warm-up) Emission measurement start Modal emission test Hot mode start  Japanese JC08 mode (hot and cold start)  Evaluated aftertreatment system Engine Without aftertreatment Original aftertreatment (DOC) DOC Engine Original & Plasma reactor DOC Engine Plasma reactor

11. 11  Introduction  Experimental  Results - Inlet gas temperature of the plasma reactor - PM mass emission - Particle size distributions - Appearance of alumina plates - Pressure drop of plasma reactor  Conclusion Outline

12. 12 Inlet gas temperature of the plasma reactor  Inlet gas of the plasma reactor was under low temperature during mode.  Hot start mode Maximum : 222.6 ºC Average : 170.4 ºC  Cold start mode Maximum : 222.0 ºC Average : 147.0 ºC Gas temperature

13. 13 PM mass emission Cold HotCombine * * Combine emission = Cold mode emission × 0.25 + Hot mode emission × 0.75 51%62% 59% 86% 93% 91% 81% 86% 84 % 15% 26% 23% Japanese new regulation (JP 2009)  The plasma reactor showed almost same removal capability in both modes.  The oxidative ability of plasma showed elective affinity for soot.  PM emission of our plasma reactor achieved JP2009 regulation (combine emission value 0.0048 g/km). 79% 77% 54% 23% 35% 91% (0.0048 g/km)

14. 14 Particle size distributions ColdHot  Particle concentrations after the plasma reactor were clearly reduced.  Non-thermal plasma could also remove nano-particles. Good 87.6%81.3% w/o aftertreatment Original w/o aftertreatment Original w/o aftertreatment Original Original & Plasma w/o aftertreatment Original Original & Plasma

15. 15 Without plasmaWith plasma Area of electrode Temporary trap Oxidation (Combustion) Appearance of alumina plates After about 300 km mode driving  PM was clearly removed on the alumina plate with plasma.  PM adsorption was observed less at downstream side. It is suggested that reactive species which came from the upstream side It is suggested that reactive species which came from the upstream side contributed to oxidize PM at the downstream side. contributed to oxidize PM at the downstream side. Exhaust gas flow

16. 16 Pressure drop of the plasma reactor  The plasma reactor maintained lower pressure drop during consecutive mode tests.  It is suggested that PM was successively removed by the plasma reactor.

17. 17 Conclusion 1. PM emission could satisfy JP2009 emission regulation of 0.005 g/km by installing the plasma reactor after the original DOC. The plasma reactor showed successive high removal rate for ISF which is not easily oxidized with catalytic reactions compared with SOF. 2. The plasma reactor could remove PM under low temperature. Such a removal ability is a great advantage compared with a catalyst or a DPF which requires active regeneration. 3. The plasma reactor showed low pressure drop during JC08 mode. Such low pressure drop was achieved due to the structural characteristic of plasma reactor. This plasma system is expected to be one of the promising technologies for diesel emission control.

18. 18 Acknowledgement This work is supported by Japanese government through NEDO. New Energy Industrial Technology Development Organization Thank you for your attention ! We would like to thank Professor Yoshimasa Nihei [Tokyo University of Science] Professor Hajime Fujimoto [Doshisha University] Professor Yoichi Hori [The University of Tokyo] Professor Yasutake Teraoka [Kyushu University] Comprehensive Technological Development of Innovative, Next-Generation, Low-Pollution Vehicles R&D of Innovative After-Treatment Systems

19. 19 END

20. 20 NOx emission Cold Hot Combine

21. 21 Discharge system Oscilloscope AC 100V Plasma Reactor High voltage probe Current Transformer Pulse Power Supply DC Power Supply DC powersupply (DC voltage : 0-600V) Pulse power supply driven by DC power supply (Pulse peak voltage : ~ 10kV)

22. 22 Electrode Dielectric Electrode Gas flow Glass wool spacer New electrode Alumina plate (dielectric) Discarge PM (Mass-produced flat plate of general alumina) Plasma reactor and new electrode Ref: S. Yao (RITE), AIChE J., Vol. 53, 1891-1897 (2007)

23. 23  Thermal plasma : All particles are in state of high temperatures. Gas show high temperatures. Gas show high temperatures.  Non-thermal plasma : Only electrons show high temperatures. Gas remains in state of almost 'cold' (ambient temperature). Gas remains in state of almost 'cold' (ambient temperature). 05101520 10 1 10 2 10 3 10 4 10 5 10 6 Gas Temperature Rise [  C] Electron Temperature [eV] RF Jet n e ~ 10 18 cm -3 n e ~ 10 15 cm -3 n e ~ 10 12 cm -3 Arc MW Torch Line of T gas  T electron n e ~ 10 12 cm -3 Pulsed Corona & DBD MH Cho, postech, 8th APCPST, 2006 Pulsed Corona(+) cylinderbarrierrod wirecylinder Dielectric Barrier Discharge Thermal and Non-thermal plasma

24. 24 Our concept for reducing each emissions 2CD Plasma Reactor DOC Cooled EGR NOx reduction Soot and SOF reduction CO, HC and SOF reduction NOx catalyst NOx reduction  NOx is reduced by control of engine combustion or NOx catalyst.  CO, HC and SOF are reduced by the diesel oxidation catalyst.  Soot and SOF are reduced by the plasma reactor.

25. 25 Equation for PM removal rates Emission w/ o aftertreatment ー Original or Original & Plasma emission Emission w/ o aftertreatment × 100 (%) PM removal rate from emission w/o aftertreatment = Original DOC emission ー Original & Plasma emission Original DOC emission × 100 (%) PM removal rate from original DOC emission =

26. 26 PM number emission (CPC) ColdHot Combine

27. 27 Japanese 10-15 mode and JC08 mode  Japanese JC08 mode  Japanese 10-15 mode

28. 28 Gas temperature and pressure drop  The plasma reactor could remove PM effectively even under low temperatures.  The plasma reactor showed lower pressure drop below 3.8 kPa during mode.  Cold start mode Maximum : 222.0 ºC Average : 147.0 ºC  Hot start mode Maximum : 222.6 ºC Average : 170.4 ºC Gas temperature  Cold start mode Maximum : 3.4 kPa  Hot start mode Maximum : 3.8 kPa Pressure drop

29. 29 PM mass emission (JP2009) Cold (JC08) Hot (10-15)Combine * * Combine emission = JC08 Cold mode emission × 0.25 + 10-15 Hot mode emission × 0.75 Japanese new regulation (JP 2009) Combine emission value 0.0038 g/km

30. 30 Total particle concentrations

31. 31 Fluctuation of pressure drop during mode tests  Maximum pressure drop didn't increase during consecutive mode tests.  It is suggested that PM was successively removed by the plasma reactor.