大功率柴油机尿素-选择性催化还原系统混合器仿真与试验研究
|
摘要
针对大功率柴油机选择性催化还原技术(SCR)应用需求,设计了两种混合器方案,两方案的差别在于是否在喷射点前安装前置混合器。利用计算流体动力学(CFD)技术对两方案的气流轨迹、尿素分解率、分布均匀性及压力损失进行了仿真分析,并进行D2排放循环测试验证两方案的NO_x转化效率。仿真及试验结果表明:安装前置混合器可以产生旋流,促进尿素液滴与气流充分混合,提高尿素分解率和NH_3分布均匀性,压力损失增高;安装前置混合器能够提高SCR催化器的NO_x转化效率,并可以通过标定优化使NO_x比排放满足欧盟第五阶段排放限值要求。研究表明,前置混合器更能适应当前及未来大功率柴油机NO_x排放法规限值要求。
According to the requirements of the selective catalytic reduction(SCR)technology of a high power diesel engine,two schemes of installing and not installing apre-mixer before the injection point were designed.The computational fluid dynamics(CFD)technology was used to simulate the gas-flow trajectory,urea decomposition rate,NH_3distribution uniformity and pressure loss of the two schemes,and the D2emission cycle test was carried out to verify the NO_xconversion efficiency of the two schemes.The simulation and experimental results show that compared to the solution without a pre-mixer,the pre-mixer can generate a swirl to promote the full mixing of urea droplets with gas flow,and increase the urea decomposition rate and NH_3distribution uniformity at a higher pressure loss,thereby improving the NO_(x )conversion efficiency of the SCR system,which makes the NO_(x )emissions meet EU Stage V emission regulations,and provides a bright future for the development of higher power diesel engines.
According to the requirements of the selective catalytic reduction(SCR)technology of a high power diesel engine,two schemes of installing and not installing apre-mixer before the injection point were designed.The computational fluid dynamics(CFD)technology was used to simulate the gas-flow trajectory,urea decomposition rate,NH_3distribution uniformity and pressure loss of the two schemes,and the D2emission cycle test was carried out to verify the NO_xconversion efficiency of the two schemes.The simulation and experimental results show that compared to the solution without a pre-mixer,the pre-mixer can generate a swirl to promote the full mixing of urea droplets with gas flow,and increase the urea decomposition rate and NH_3distribution uniformity at a higher pressure loss,thereby improving the NO_(x )conversion efficiency of the SCR system,which makes the NO_(x )emissions meet EU Stage V emission regulations,and provides a bright future for the development of higher power diesel engines.
引文
[1]帅石金,唐韬,赵彦光,等.柴油车排放法规及后处理技术的现状与展望[J].汽车安全与节能学报,2012,3(3):200-217.SHUAI S J,TANG T,ZHAO Y G,et al.State of art and outlook of diesel emission regulations and aftertreatment technologies[J].Journal of Automotive Safety and Energy,2012,3(3):200-217.
[2]张俊,唐韬,曹东晓,等.重型柴油机欧Ⅵ后处理系统构型方案试验研究[J].内燃机工程,2017,38(1):7-11.ZHANG J,TANG T,CAO D X,et al.Experimental study of aftertreatment system configurations for EuroⅣheavy-duty diesel engines[J].Chinese Internal Combustion Engine Engineering,2017,38(1):7-11.
[3]王谦,张铎,王静,等.车用柴油机Urea-SCR系统数值分析与参数优化[J].内燃机学报,2013,31(4):343-348.WANG Q,ZHANG D,WANG J,et al.Numerical analysis and parametric optimization on urea-SCR system of vehicle diesel[J].Transactions of CSICE,2013,31(4):343-348.
[4]臧志成,魏家星,卢凯,等.喷嘴集成式SCR混合器设计与数值模拟研究[J].内燃机工程,2017,38(4):103-108.ZANG Z C,WEI J X,LU K,et al.Design of and numerical simulation study on injector integrated SCR mixer[J].Chinese Internal Combustion Engine Engineering,2017,38(4):103-108.
[5]CAPETILLO A J,IBARRA F,STEPNIEWSKI D,et al.Multiphase modelling of SCR systems:using the Taguchi method for mixer optimisation[J].SAE International Journal of Engines,2017,10(1):61-71.
[6]PADULA G,SCHIFFMANN P,LECOMPTE M,et al.Computational fluid dynamics study of gaseous ammonia mixing in an exhaust pipe using static mixers[J].2017,10(4):1894-1902.
[7]LEE C.Numerical and experimental investigation of evaporation and mixture uniformity of urea-water solution in selective catalytic reduction system[J].Transportation Research Part D:Transport and Environment,2018,60:210-224.
[8]TAN L,FENG P F,YANG S B,et al.CFD studies on effects of SCR mixers on the performance of urea conversion and mixing of the reducing agent[J].Chemical Engineering&Processing Process Intensification,2018,123:82-88.
[9]谭理刚,冯鹏飞,杨树宝,等.基于CFD的Urea-SCR混合器性能研究[J].内燃机工程,2018,39(4):61-66.TAN L G,FENG P F,YANG S B,et al.Study on static mixer performance in urea-SCR systems based on CFD code[J].Chinese Internal Combustion Engine Engineering,2018,39(4):61-66.
[10]DRENNAN S,KUMAR G,QUAN S P,et al.Application of automatic meshing to urea-water injection simulation for engine aftertreatment[C/OL].SAE Paper,2015,2015-01-1057.(2015-04-14).https://doi.org/11.4271/2015-01-1057.
[11]REIHANI A,CORSON B,HOARD J W,et al.Rapidly pulsed reductants in diesel NOxreduction by lean NOxtraps:effects of mixing uniformity and reductant type[C/OL].SAEPaper,2016,2016-01-0956.(2016-04-05).https://doi.org/10.4271/2016-01-0956.
[12]祝能,吕林,杨栋.携带SCR系统的柴油机排气管中生成沉积物的影响因素研究[J].内燃机工程,2015,36(6):8-13.ZHU N,LL,YANG D.Study on factors influencing the deposit formation in the exhaust pipes of SCR diesel engine[J].Chinese Internal Combustion Engine Engineering,2015,36(6):8-13.
[13]LIAO Y J,FURRER R,EGGENSCHWILER P D.Experimental investigation of the heat transfer characteristics of spray/wall interaction in diesel selective catalytic reduction systems[J].Fuel,2016,190:163-173.
[14]GAN X B,YAO D W,WU F,et al.Modeling and simulation of urea-water-solution droplet evaporation and thermolysis processes for SCR systems[J].Chinese Journal of Chemical Engineering,2016,24(8):1065-1073.
[15]WEEKS C L,DAN R I,HAN S,et al.Analytical investigation of urea deposits in SCR system[J].SAEInternational Journal of Engines,2015,8(3):1219-1239.
[16]CIARDELLI C,NOVA I,TRONCONI E,et al.Reactivity of NO/NO2-NH3,SCR system for diesel exhaust aftertreatment:identification of the reaction network as a function of temperature and NO2,feed content[J].Applied Catalysis BEnvironmental,2007,70(1):80-90.
[17]BIRKHOLD F,MEINGAST U,WASSERMANN P,et al.Modeling and simulation of the injection of urea-water-solution for automotive SCR DeNOx-systems[J].Applied Catalysis BEnvironmental,2007,70(1):119-127.
[18]KAARIO O T,VUORINEN V,ZHU L,et al.Mixing and evaporation analysis of a high-pressure SCR system using a hybrid LES-RANS approach[J].Energy,2017,120:827-841.
[19]张文娟,帅石金,董红义,等.尿素SCR-NOx催化器流动、还原剂喷雾及表面化学反应三维数值模拟[J].内燃机学报,2007,25(5):433-438.ZHANG W J,SHUAI S J,DONG H Y,et al.3D modeling of flow,spraying of reductant and surface chemical reaction in diesel urea SCR-NOx catalytic converter[J].Transactions of CSICE,2007,25(5):433-438.
[20]TANG T,ZHANG J,SHUAI S J,et al.Urea decomposition at low temperature in SCR systems for diesel engines[C/OL].SAE Paper,2014,2014-01-2808.(2014-10-13).https://doi.org/11.4271/2014-01-2808.
[21]中华人民共和国环境保护部,国家质量监督检验检疫总局.非道路移动机械用柴油机排气污染物排放限值及测量方法(中国第三、四阶段):GB 20891-2014[S].北京:中国环境科学出版社,2014.
[2]张俊,唐韬,曹东晓,等.重型柴油机欧Ⅵ后处理系统构型方案试验研究[J].内燃机工程,2017,38(1):7-11.ZHANG J,TANG T,CAO D X,et al.Experimental study of aftertreatment system configurations for EuroⅣheavy-duty diesel engines[J].Chinese Internal Combustion Engine Engineering,2017,38(1):7-11.
[3]王谦,张铎,王静,等.车用柴油机Urea-SCR系统数值分析与参数优化[J].内燃机学报,2013,31(4):343-348.WANG Q,ZHANG D,WANG J,et al.Numerical analysis and parametric optimization on urea-SCR system of vehicle diesel[J].Transactions of CSICE,2013,31(4):343-348.
[4]臧志成,魏家星,卢凯,等.喷嘴集成式SCR混合器设计与数值模拟研究[J].内燃机工程,2017,38(4):103-108.ZANG Z C,WEI J X,LU K,et al.Design of and numerical simulation study on injector integrated SCR mixer[J].Chinese Internal Combustion Engine Engineering,2017,38(4):103-108.
[5]CAPETILLO A J,IBARRA F,STEPNIEWSKI D,et al.Multiphase modelling of SCR systems:using the Taguchi method for mixer optimisation[J].SAE International Journal of Engines,2017,10(1):61-71.
[6]PADULA G,SCHIFFMANN P,LECOMPTE M,et al.Computational fluid dynamics study of gaseous ammonia mixing in an exhaust pipe using static mixers[J].2017,10(4):1894-1902.
[7]LEE C.Numerical and experimental investigation of evaporation and mixture uniformity of urea-water solution in selective catalytic reduction system[J].Transportation Research Part D:Transport and Environment,2018,60:210-224.
[8]TAN L,FENG P F,YANG S B,et al.CFD studies on effects of SCR mixers on the performance of urea conversion and mixing of the reducing agent[J].Chemical Engineering&Processing Process Intensification,2018,123:82-88.
[9]谭理刚,冯鹏飞,杨树宝,等.基于CFD的Urea-SCR混合器性能研究[J].内燃机工程,2018,39(4):61-66.TAN L G,FENG P F,YANG S B,et al.Study on static mixer performance in urea-SCR systems based on CFD code[J].Chinese Internal Combustion Engine Engineering,2018,39(4):61-66.
[10]DRENNAN S,KUMAR G,QUAN S P,et al.Application of automatic meshing to urea-water injection simulation for engine aftertreatment[C/OL].SAE Paper,2015,2015-01-1057.(2015-04-14).https://doi.org/11.4271/2015-01-1057.
[11]REIHANI A,CORSON B,HOARD J W,et al.Rapidly pulsed reductants in diesel NOxreduction by lean NOxtraps:effects of mixing uniformity and reductant type[C/OL].SAEPaper,2016,2016-01-0956.(2016-04-05).https://doi.org/10.4271/2016-01-0956.
[12]祝能,吕林,杨栋.携带SCR系统的柴油机排气管中生成沉积物的影响因素研究[J].内燃机工程,2015,36(6):8-13.ZHU N,LL,YANG D.Study on factors influencing the deposit formation in the exhaust pipes of SCR diesel engine[J].Chinese Internal Combustion Engine Engineering,2015,36(6):8-13.
[13]LIAO Y J,FURRER R,EGGENSCHWILER P D.Experimental investigation of the heat transfer characteristics of spray/wall interaction in diesel selective catalytic reduction systems[J].Fuel,2016,190:163-173.
[14]GAN X B,YAO D W,WU F,et al.Modeling and simulation of urea-water-solution droplet evaporation and thermolysis processes for SCR systems[J].Chinese Journal of Chemical Engineering,2016,24(8):1065-1073.
[15]WEEKS C L,DAN R I,HAN S,et al.Analytical investigation of urea deposits in SCR system[J].SAEInternational Journal of Engines,2015,8(3):1219-1239.
[16]CIARDELLI C,NOVA I,TRONCONI E,et al.Reactivity of NO/NO2-NH3,SCR system for diesel exhaust aftertreatment:identification of the reaction network as a function of temperature and NO2,feed content[J].Applied Catalysis BEnvironmental,2007,70(1):80-90.
[17]BIRKHOLD F,MEINGAST U,WASSERMANN P,et al.Modeling and simulation of the injection of urea-water-solution for automotive SCR DeNOx-systems[J].Applied Catalysis BEnvironmental,2007,70(1):119-127.
[18]KAARIO O T,VUORINEN V,ZHU L,et al.Mixing and evaporation analysis of a high-pressure SCR system using a hybrid LES-RANS approach[J].Energy,2017,120:827-841.
[19]张文娟,帅石金,董红义,等.尿素SCR-NOx催化器流动、还原剂喷雾及表面化学反应三维数值模拟[J].内燃机学报,2007,25(5):433-438.ZHANG W J,SHUAI S J,DONG H Y,et al.3D modeling of flow,spraying of reductant and surface chemical reaction in diesel urea SCR-NOx catalytic converter[J].Transactions of CSICE,2007,25(5):433-438.
[20]TANG T,ZHANG J,SHUAI S J,et al.Urea decomposition at low temperature in SCR systems for diesel engines[C/OL].SAE Paper,2014,2014-01-2808.(2014-10-13).https://doi.org/11.4271/2014-01-2808.
[21]中华人民共和国环境保护部,国家质量监督检验检疫总局.非道路移动机械用柴油机排气污染物排放限值及测量方法(中国第三、四阶段):GB 20891-2014[S].北京:中国环境科学出版社,2014.