燃烧方式对氢内燃机燃烧和排放的影响研究
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摘要
基于氢内燃机试验样机建立内燃机三维实体模型,耦合详细氢空气化学反应机理,运用Converge软件建立氢内燃机CFD仿真模型并进行验证,仿真分析了中高负荷下稀薄燃烧和当量燃烧两种燃烧方式下氢燃料内燃机的燃烧特性和NO_x排放规律。仿真结果表明:在氢气供给量相同的情况下,稀薄燃烧比当量燃烧速度更快,OH浓度更高,因而稀薄燃烧会得到更高的缸内压力,更有利于动力性的发挥;两种燃烧方式下的缸内最高平均温度较为接近,但当量燃烧方式下最高温度相位相对滞后,可以有效降低NO_x排放。采用EGR技术可以实现当量燃烧,但过大的EGR率也会带来内燃机动力性能下降。
Based on the prototype of hydrogen internal combustion engine,a three-dimensional solid model of internal combustion engine was built.Then the mechanism of hydrogen gas chemical reaction was coupled and the CFD simulation model of hydrogen internal combustion engine was established with Converge software and verified.The combustion characteristics and NO_x emission rules of hydrogen-fueled combustion engine were studied in the modes of lean burn and equivalent combustion.The simulation results show that the lean burn is faster than the equivalent combustion and the OH concentration is higher and hence the lean burn will produce a higher cylinder pressure which is more beneficial to the higher power in the case of the same hydrogen supply.The in-cylinder maximum average temperature of the two combustion modes is almost the same,but the crankshaft angle of highest temperature in the equivalent combustion mode is relatively backward,which can effectively reduce NO_x emission.EGR technology can realize equivalent combustion,but the too large EGR rate will bring about the dynamic performance decrease of internal combustion engine.
Based on the prototype of hydrogen internal combustion engine,a three-dimensional solid model of internal combustion engine was built.Then the mechanism of hydrogen gas chemical reaction was coupled and the CFD simulation model of hydrogen internal combustion engine was established with Converge software and verified.The combustion characteristics and NO_x emission rules of hydrogen-fueled combustion engine were studied in the modes of lean burn and equivalent combustion.The simulation results show that the lean burn is faster than the equivalent combustion and the OH concentration is higher and hence the lean burn will produce a higher cylinder pressure which is more beneficial to the higher power in the case of the same hydrogen supply.The in-cylinder maximum average temperature of the two combustion modes is almost the same,but the crankshaft angle of highest temperature in the equivalent combustion mode is relatively backward,which can effectively reduce NO_x emission.EGR technology can realize equivalent combustion,but the too large EGR rate will bring about the dynamic performance decrease of internal combustion engine.
引文
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[2]胡灿伟.机动车已成空气污染主力[J].生态经济,2016,32(4):10-13.
[3]马冬,尹航,丁焰,等.基于大数据的中国在用车排放状况研究[J].环境污染与防治,2016,38(7):42-48,55.
[4]王丽君,杨振中.氢燃料内燃机研究新进展[J].拖拉机与农用运输车,2005(4):89-91.
[5] Verhelst S,Demuynck J,Sierens R,et al.Impact of variable valve timing on power,emissions and backfire of a bi-fuel hydrogen/gasoline engine[J].International Journal of Hydrogen Energy,2010,35(9):4399-4408.
[6] Duan J F,Liu F S,Yang Z Z,et al.Study on the NOxemissions mechanism of an HICE under high load[J].International Journal of Hydrogen Energy,2017,42:22027-22035.
[7]孙柏刚,向清华,刘福水.氢内燃机及整车性能试验研究[J].北京理工大学学报,2012,32(10):1026-1030.
[8] Safari H,Jazayeri S A,Ebrahimi R.Potentials of NOx emission reduction methods in SI hydrogen enginesSimulation study[J].Int.J.Hydrogen Energy,2009(34):1-11.
[9] Subramanian V,Mallikarjuna J M,Ramesh A.Effect of water injection and spark timing on the nitric oxide emission and combustion parameters of a hydrogen fuelled spark ignition engine[J].International Journal of Hydrogen Energy,2007(32):1159-1173.
[10] Ingenito A,Agresta A,Andriani R,et al.NOx reduction strategies for high speed hydrogen fuelled vehicles[J].Int J Hydrogen Energy,2015,40:5186-5196.
[11] Yadav V S,Sharma D,Soni S L.Performance and combustion analysis of hydrogen-fuelled C.I.engine with EGR[J].Int.J.Hydrogen Energy,2015,40:4382-4391.