排气余热辅助低温等离子体再生柴油机颗粒捕集器试验
|
摘要
为探究低温等离子体(non-thermal plasma,NTP)对无外加热源的柴油机颗粒捕集器(diesel particulate filter,DPF)的再生过程与再生效果,搭建了排气余热辅助NTP再生DPF的试验系统。借助发动机停机后的排气余热,利用DBD(dielectric barrier discharge)型NTP发生器,对处于降温过程的DPF进行再生试验研究。结果表明:随着DPF温度的下降,NTP中O3的分解反应减弱,PM(particulate matter)氧化反应加剧,DPF内部出现温度不降反升的现象,氧化区域自DPF前端逐渐向后端延伸,DPF径向中点处氧化反应最为剧烈,DPF轴向剖面上残余积碳呈现?形。再生后DPF内部残余积碳中可溶性有机成分SOF(soluble organic fraction)明显减少,且NTP处理能够降低PM中SOF及DS(dry soot)的表观活化能。整个再生过程中,DPF内部大量积碳被氧化去除。排气余热辅助的NTP再生技术,实现了对无外加热源的DPF的有效再生,使得DPF排气背压下降达69%。该文证实了排气余热辅助NTP再生DPF的可行性,为NTP再生DPF技术的应用提供了试验依据。
Diesel engines are widely applied in the field of transportation and manufacturing because of their dynamic and economic performance. Compared to gasoline engine, the hydrocarbon(HC) and carbon monoxide(CO) emissions from diesel engine are much lower. However, diesel engine emits huge quantities of particulate matter(PM) which pose a great threat to human health and environmental protection. As emission regulations are becoming gradually stricter, it is imperative to stringently control diesel PM emission with a feasible after-treatment technic. The technology of diesel particulate filter(DPF) is considered as the most effective mean to reduce diesel PM emission. The key of DPF technology is regeneration of the DPF, which is to timely remove the carbon deposit captured by DPF. Non-thermal plasma(NTP) technology is a promising method to control diesel emission. Reactive species generated by NTP reactor can activate complicated chemical reactions under common condition. Therefore, NTP technology has been used to remove PM deposited in DPF and become a new research hotspot in the field of DPF regeneration. Other studies have shown DPF could be effectively regenerated by NTP when the regeneration temperature was precisely controlled by an extra heater. In this work, an experimental system of DPF regeneration was constructed to investigate the regeneration effect in which DPF was not heated by an external heat source. Aided by the exhaust waste heat after engine outage, an experimental study on DPF regeneration was conducted by using a dielectric barrier discharge(DBD) NTP reactor. In the process of DPF regeneration, reactive species and PM generated exothermic oxidation reactions. Infrared gas analyzer was used to measure the volume fraction of CO and CO2 that were the main oxidation products in DPF regeneration. Twelve pairs of thermocouples were distributed in the interior of DPF to monitor the temperature change in the regeneration process. Based on NTP technology aided by exhaust waste heat, the regeneration process was investigated by analyzing the concentration change of oxidation products and the temperature change of each measuring point. Engine exhaust pipe was equipped with pitot tubes to measure the exhaust backpressure before and after regeneration. The regeneration effect was evaluated by backpressure variation of DPF after regeneration. In addition, an auxiliary test was conducted to explore the decomposition law of O3 versus temperature, contributing to the analysis of regeneration process. Thermogravimetric analysis(TGA) was performed to compare the physicochemical properties of deposit before and after NTP treatment. Results showed that NTP technology aided by exhaust waste heat exerted a good regeneration effect on DPF without an external heat source, dramatically lowering the backpressure of DPF by 69%. With the decrease of temperature, the decomposition of O3 in NTP was weakened. Therefore oxidation reaction of PM was intensified, causing the rising of the internal temperature of DPF instead of dropping. In the regeneration process, the oxidation area extended from the front of DPF to the back. The most vigorous oxidation reaction occurred at the radial midpoint of DPF and the remnant PM after regeneration on the axial section of DPF showed a ? shape. The soluble organic fraction(SOF) in the remnant deposit reduced after DPF regeneration. NTP treatment reduced the activation energy of PM both in SOF and in dry soot(DS). In the whole regeneration process, the mass of carbon in the PM decomposed was more than 6 g. This work proves the feasibility of the DPF regeneration by NTP without an external heat source, and provides experimental basis for vehicle application of the NTP technology.
Diesel engines are widely applied in the field of transportation and manufacturing because of their dynamic and economic performance. Compared to gasoline engine, the hydrocarbon(HC) and carbon monoxide(CO) emissions from diesel engine are much lower. However, diesel engine emits huge quantities of particulate matter(PM) which pose a great threat to human health and environmental protection. As emission regulations are becoming gradually stricter, it is imperative to stringently control diesel PM emission with a feasible after-treatment technic. The technology of diesel particulate filter(DPF) is considered as the most effective mean to reduce diesel PM emission. The key of DPF technology is regeneration of the DPF, which is to timely remove the carbon deposit captured by DPF. Non-thermal plasma(NTP) technology is a promising method to control diesel emission. Reactive species generated by NTP reactor can activate complicated chemical reactions under common condition. Therefore, NTP technology has been used to remove PM deposited in DPF and become a new research hotspot in the field of DPF regeneration. Other studies have shown DPF could be effectively regenerated by NTP when the regeneration temperature was precisely controlled by an extra heater. In this work, an experimental system of DPF regeneration was constructed to investigate the regeneration effect in which DPF was not heated by an external heat source. Aided by the exhaust waste heat after engine outage, an experimental study on DPF regeneration was conducted by using a dielectric barrier discharge(DBD) NTP reactor. In the process of DPF regeneration, reactive species and PM generated exothermic oxidation reactions. Infrared gas analyzer was used to measure the volume fraction of CO and CO2 that were the main oxidation products in DPF regeneration. Twelve pairs of thermocouples were distributed in the interior of DPF to monitor the temperature change in the regeneration process. Based on NTP technology aided by exhaust waste heat, the regeneration process was investigated by analyzing the concentration change of oxidation products and the temperature change of each measuring point. Engine exhaust pipe was equipped with pitot tubes to measure the exhaust backpressure before and after regeneration. The regeneration effect was evaluated by backpressure variation of DPF after regeneration. In addition, an auxiliary test was conducted to explore the decomposition law of O3 versus temperature, contributing to the analysis of regeneration process. Thermogravimetric analysis(TGA) was performed to compare the physicochemical properties of deposit before and after NTP treatment. Results showed that NTP technology aided by exhaust waste heat exerted a good regeneration effect on DPF without an external heat source, dramatically lowering the backpressure of DPF by 69%. With the decrease of temperature, the decomposition of O3 in NTP was weakened. Therefore oxidation reaction of PM was intensified, causing the rising of the internal temperature of DPF instead of dropping. In the regeneration process, the oxidation area extended from the front of DPF to the back. The most vigorous oxidation reaction occurred at the radial midpoint of DPF and the remnant PM after regeneration on the axial section of DPF showed a ? shape. The soluble organic fraction(SOF) in the remnant deposit reduced after DPF regeneration. NTP treatment reduced the activation energy of PM both in SOF and in dry soot(DS). In the whole regeneration process, the mass of carbon in the PM decomposed was more than 6 g. This work proves the feasibility of the DPF regeneration by NTP without an external heat source, and provides experimental basis for vehicle application of the NTP technology.
引文
[1]Yang Jiacheng,Jiang Yu,Karavalakis G,et al.Impacts of dimethyl carbonate blends on gaseous and particulate emissions from a heavy-duty diesel engine[J].Fuel,2016,184:681-688.
[2]Chen Pingen,Wang Junmin.Air-fraction modeling for simultaneous diesel engine NOx and PM emissions control during active DPF regenerations[J].Applied Energy,2014,122:310-320.
[3]Zheng Xuan,Wu Ye,Zhang Shaojun,et al.Joint measurements of black carbon and particle mass for heavyduty diesel vehicles using a portable emission measurement system[J].Atmospheric Environment,2016,141:435-442.
[4]梅德清,赵翔,王书龙,等.柴油机排放颗粒物的热重特性分析[J].农业工程学报,2013,29(16):50-56.Mei Deqing,Zhao Xiang,Wang Shulong,et al.Thermogravimetric characteristics analysis of particulate matter of emission of divided diesel[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2013,29(16):50-56.(in Chinese with English abstract)
[5]Lee S,Kim T Y.Performance and emission characteristics of a DI diesel engine operated with diesel/DEE blended fuel[J].Applied Thermal Engineering,2017,121:454-461.
[6]Saravanan N,Nagarajan G.Experimental investigation on a DI dual fuel engine with hydrogen injection[J].International Journal of Energy Research,2009,33(3):295-308.
[7]Bensaid S,Caroca C J,Russo N,et al.Detailed investigation of non-catalytic DPF regeneration[J].Canadian Journal of Chemical Engineering,2011,89(2):401-407.
[8]中华人民共和国国家质量监督检验检疫总局.轻型汽车污染物排放限值及测量方法(中国Ⅲ、Ⅳ阶段):GB18352.3-2005[S].北京:中国环境科学出版社,2005.
[9]中华人民共和国国家质量监督检验检疫总局.轻型汽车污染物排放限值及测量方法(中国第五阶段):GB18352.5-2013[S].北京:中国环境科学出版社,2013.
[10]Palma V,Ciambelli P,Meloni E,et al.Catalytic DPFmicrowave assisted active regeneration[J].Fuel,2015,140:50-61.
[11]Chen K,Martirosyan K S,Luss D.Counter-intuitive temperature excursions during regeneration of a diesel particulate filter[J].Aiche Journal,2011,57(8):2229-2236.
[12]Mokhri M A,Abdullah N R,Abdullah S A,et al.Soot filtration recent simulation analysis in diesel particulate filter(DPF)[J].Procedia Engineering,2012,41:1750-1755.
[13]Hanamura K,Karin P,Cui L,et al.Micro and macroscopic visualization of particulate matter trapping and regeneration processes in wall-flow diesel particulate filters[J].International Journal of Engine Research,2009,10(5):305-321.
[14]韦雄,冒晓建,祝轲卿,等.基于机内技术的DPF再生控制策略研究[J].农业机械学报,2013,44(11):1-5.Wei Xiong,Mao Xiaojian,Zhu Keqing,et al.Control strategy of DPF regeneration based on machine technology[J].Transactions of the Chinese Society for Agricultural Machinery,2013,44(11):1-5.(in Chinese with English abstract)
[15]Bensaid S,Marchisio D L,Fino D,et al.Modelling of diesel particulate filtration in wall-flow traps[J].Chemical Engineering Journal,2009,154(1):211-218.
[16]Beatrice C,Iorio S D,Guido C,et al.Detailed characterization of particulate emissions of an automotive catalyzed DPFusing actual regeneration strategies[J].Experimental Thermal&Fluid Science,2012,39(5):45-53.
[17]Wang Pan,Gu Wenye,Lei Lili,et al.Micro-structural and components evolution mechanism of particular matter from diesel engines with non-thermal plasma technology[J].Applied Thermal Engineering,2015,91:1-10.
[18]Kuwahara T,Nakaguchi H,Kuroki T,et al.Continuous reduction of cyclic adsorbed and desorbed NOx in diesel emission using non-thermal plasma[J].Journal of Hazardous Materials,2016,308:216-224.
[19]Ranji-Burachaloo H,Masoomi-Godarzi S,Khodadadi A A,et al.Synergetic effects of plasma and metal oxide catalysts on diesel soot oxidation[J].Applied Catalysis B:Environmental,2016,182:74-84.
[20]Kuwahara T,Nakaguchi H,Kuroki T,et al.Continuous reduction of cyclic adsorbed and desorbed NOx in diesel emission using nonthermal plasma[J].Journal of Hazardous Materials,2016,308:216-224.
[21]王军,蔡忆昔,赵卫东,等.低温等离子体喷射系统降低排放及再生DPF的试验研究[J].车用发动机,2010(3):79-82.Wang Jun,Cai Yixi,Zhao Weidong,et al.Experimental study on NTP injection system reducing diesel engine emissions and regenerating DPF[J].Vehicle Engine,2010(3):79-82.(in Chinese with English abstract)
[22]Okubo M,Arita N,Kuroki T,et al.Carbon particulate matter incineration in diesel engine emissions using indirect nonthermal plasma processing[J].Thin Solid Films,2007,515(9):4289-4295.
[23]Okubo M,Kuroki T,Kawasaki S,et al.Continuous regeneration of ceramic particulate filter in stationary diesel engine by nonthermal-plasma-induced ozone injection[J].IEEE Transactions on Industry Applications,2009,45(5):1568-1574.
[24]Shi Yunxi,Cai Yixi,Li Xiaohua,et al.Mechanism and method of DPF regeneration by oxygen radical generated by NTP technology[J].International Journal of Automotive Technology,2014,15(6):871-876.
[25]Ma Chaochen,Gao Jianbing,Zhong Lei,et al.Experimental investigation of the oxidation behaviour and thermal kinetics of diesel particulate matter with non-thermal plasma[J].Applied Thermal Engineering,2016,99:1110-1118.
[26]Yao Shuiliang,Wu Zuliang,Han Jingyi,et al.Study of ozone generation in an atmospheric dielectric barrier discharge reactor[J].Journal of Electrostatics,2015,75:35-42.
[27]李小华,李伟俊,蔡忆昔,等.氧气/空气源低温等离子体发生器的性能对比分析[J].农业工程学报,2016,32(11):103-108.Li Xiaohua,Li Weijun,Cai Yixi,et al.Comparative analysis on characteristics in non-thermal plasma reactor with oxygen and air[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(11):103-108.(in Chinese with English abstract)
[28]雷利利,蔡忆昔,王攀,等.NTP技术对柴油机颗粒物组分及热重特性的影响[J].内燃机学报,2013,31(2):144-147.Lei Lili,Cai Yixi,Wang Pan,et al.Influence on component and thermo-gravimetric characteristics of diesel particulate matter by NTP technology[J].Transactions of Csice,2013,31(2):144-147.(in Chinese with English abstract)
[29]Yusop A F,Yasin M H M,Mamat R,et al.PM emission of diesel engines using ester-ethanol-diesel blended fuel[J].Procedia Engineering,2013,53:530-535.
[30]Shi Yunxi,Cai Yixi,Wang Jing,et al.Influence of PM size distribution and ingredients on DPF regeneration by non-thermal plasma technology[J].Plasma Chemistry and Plasma Processing,2016:1-14.
[31]Kalogirou M,Samaras Z.A thermogravimetic kinetic study of uncatalyzed diesel soot oxidation[J].Journal of Thermal Analysis and Calorimetry,2009,98(1):215-224.
[32]Stratakis G A,Stamatelos A M.Thermogravimetric analysis of soot emitted by a modern diesel engine run on catalyst-doped fuel[J].Combustion and Flame,2003,132(1):157-169.
[2]Chen Pingen,Wang Junmin.Air-fraction modeling for simultaneous diesel engine NOx and PM emissions control during active DPF regenerations[J].Applied Energy,2014,122:310-320.
[3]Zheng Xuan,Wu Ye,Zhang Shaojun,et al.Joint measurements of black carbon and particle mass for heavyduty diesel vehicles using a portable emission measurement system[J].Atmospheric Environment,2016,141:435-442.
[4]梅德清,赵翔,王书龙,等.柴油机排放颗粒物的热重特性分析[J].农业工程学报,2013,29(16):50-56.Mei Deqing,Zhao Xiang,Wang Shulong,et al.Thermogravimetric characteristics analysis of particulate matter of emission of divided diesel[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2013,29(16):50-56.(in Chinese with English abstract)
[5]Lee S,Kim T Y.Performance and emission characteristics of a DI diesel engine operated with diesel/DEE blended fuel[J].Applied Thermal Engineering,2017,121:454-461.
[6]Saravanan N,Nagarajan G.Experimental investigation on a DI dual fuel engine with hydrogen injection[J].International Journal of Energy Research,2009,33(3):295-308.
[7]Bensaid S,Caroca C J,Russo N,et al.Detailed investigation of non-catalytic DPF regeneration[J].Canadian Journal of Chemical Engineering,2011,89(2):401-407.
[8]中华人民共和国国家质量监督检验检疫总局.轻型汽车污染物排放限值及测量方法(中国Ⅲ、Ⅳ阶段):GB18352.3-2005[S].北京:中国环境科学出版社,2005.
[9]中华人民共和国国家质量监督检验检疫总局.轻型汽车污染物排放限值及测量方法(中国第五阶段):GB18352.5-2013[S].北京:中国环境科学出版社,2013.
[10]Palma V,Ciambelli P,Meloni E,et al.Catalytic DPFmicrowave assisted active regeneration[J].Fuel,2015,140:50-61.
[11]Chen K,Martirosyan K S,Luss D.Counter-intuitive temperature excursions during regeneration of a diesel particulate filter[J].Aiche Journal,2011,57(8):2229-2236.
[12]Mokhri M A,Abdullah N R,Abdullah S A,et al.Soot filtration recent simulation analysis in diesel particulate filter(DPF)[J].Procedia Engineering,2012,41:1750-1755.
[13]Hanamura K,Karin P,Cui L,et al.Micro and macroscopic visualization of particulate matter trapping and regeneration processes in wall-flow diesel particulate filters[J].International Journal of Engine Research,2009,10(5):305-321.
[14]韦雄,冒晓建,祝轲卿,等.基于机内技术的DPF再生控制策略研究[J].农业机械学报,2013,44(11):1-5.Wei Xiong,Mao Xiaojian,Zhu Keqing,et al.Control strategy of DPF regeneration based on machine technology[J].Transactions of the Chinese Society for Agricultural Machinery,2013,44(11):1-5.(in Chinese with English abstract)
[15]Bensaid S,Marchisio D L,Fino D,et al.Modelling of diesel particulate filtration in wall-flow traps[J].Chemical Engineering Journal,2009,154(1):211-218.
[16]Beatrice C,Iorio S D,Guido C,et al.Detailed characterization of particulate emissions of an automotive catalyzed DPFusing actual regeneration strategies[J].Experimental Thermal&Fluid Science,2012,39(5):45-53.
[17]Wang Pan,Gu Wenye,Lei Lili,et al.Micro-structural and components evolution mechanism of particular matter from diesel engines with non-thermal plasma technology[J].Applied Thermal Engineering,2015,91:1-10.
[18]Kuwahara T,Nakaguchi H,Kuroki T,et al.Continuous reduction of cyclic adsorbed and desorbed NOx in diesel emission using non-thermal plasma[J].Journal of Hazardous Materials,2016,308:216-224.
[19]Ranji-Burachaloo H,Masoomi-Godarzi S,Khodadadi A A,et al.Synergetic effects of plasma and metal oxide catalysts on diesel soot oxidation[J].Applied Catalysis B:Environmental,2016,182:74-84.
[20]Kuwahara T,Nakaguchi H,Kuroki T,et al.Continuous reduction of cyclic adsorbed and desorbed NOx in diesel emission using nonthermal plasma[J].Journal of Hazardous Materials,2016,308:216-224.
[21]王军,蔡忆昔,赵卫东,等.低温等离子体喷射系统降低排放及再生DPF的试验研究[J].车用发动机,2010(3):79-82.Wang Jun,Cai Yixi,Zhao Weidong,et al.Experimental study on NTP injection system reducing diesel engine emissions and regenerating DPF[J].Vehicle Engine,2010(3):79-82.(in Chinese with English abstract)
[22]Okubo M,Arita N,Kuroki T,et al.Carbon particulate matter incineration in diesel engine emissions using indirect nonthermal plasma processing[J].Thin Solid Films,2007,515(9):4289-4295.
[23]Okubo M,Kuroki T,Kawasaki S,et al.Continuous regeneration of ceramic particulate filter in stationary diesel engine by nonthermal-plasma-induced ozone injection[J].IEEE Transactions on Industry Applications,2009,45(5):1568-1574.
[24]Shi Yunxi,Cai Yixi,Li Xiaohua,et al.Mechanism and method of DPF regeneration by oxygen radical generated by NTP technology[J].International Journal of Automotive Technology,2014,15(6):871-876.
[25]Ma Chaochen,Gao Jianbing,Zhong Lei,et al.Experimental investigation of the oxidation behaviour and thermal kinetics of diesel particulate matter with non-thermal plasma[J].Applied Thermal Engineering,2016,99:1110-1118.
[26]Yao Shuiliang,Wu Zuliang,Han Jingyi,et al.Study of ozone generation in an atmospheric dielectric barrier discharge reactor[J].Journal of Electrostatics,2015,75:35-42.
[27]李小华,李伟俊,蔡忆昔,等.氧气/空气源低温等离子体发生器的性能对比分析[J].农业工程学报,2016,32(11):103-108.Li Xiaohua,Li Weijun,Cai Yixi,et al.Comparative analysis on characteristics in non-thermal plasma reactor with oxygen and air[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(11):103-108.(in Chinese with English abstract)
[28]雷利利,蔡忆昔,王攀,等.NTP技术对柴油机颗粒物组分及热重特性的影响[J].内燃机学报,2013,31(2):144-147.Lei Lili,Cai Yixi,Wang Pan,et al.Influence on component and thermo-gravimetric characteristics of diesel particulate matter by NTP technology[J].Transactions of Csice,2013,31(2):144-147.(in Chinese with English abstract)
[29]Yusop A F,Yasin M H M,Mamat R,et al.PM emission of diesel engines using ester-ethanol-diesel blended fuel[J].Procedia Engineering,2013,53:530-535.
[30]Shi Yunxi,Cai Yixi,Wang Jing,et al.Influence of PM size distribution and ingredients on DPF regeneration by non-thermal plasma technology[J].Plasma Chemistry and Plasma Processing,2016:1-14.
[31]Kalogirou M,Samaras Z.A thermogravimetic kinetic study of uncatalyzed diesel soot oxidation[J].Journal of Thermal Analysis and Calorimetry,2009,98(1):215-224.
[32]Stratakis G A,Stamatelos A M.Thermogravimetric analysis of soot emitted by a modern diesel engine run on catalyst-doped fuel[J].Combustion and Flame,2003,132(1):157-169.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |