燃空当量比对甲醇发动机燃烧及非法规排放的影响
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摘要
基于一款经柴油机改装的缸内直喷点燃式甲醇发动机,使用三维流体动力学模拟软件AVL-Fire耦合甲醇氧化反应机理,研究了不同燃空当量比对缸内混合气浓度分布、燃烧特性及未燃甲醇和甲醛排放的影响。结果表明:当燃空当量比增加时,缸内最高燃烧温度、最高燃烧压力及放热率峰值均显著升高,甲醛和未燃甲醇排放均得到改善;当燃空当量比从0.33增加到0.67时,最高燃烧压力、燃烧温度和放热率峰值分别增加65%,72%及51%;燃空比超过0.4时,未燃甲醇及甲醛排放急剧减小,且主要集中在气缸壁附近。
The influences of different fuel-air equivalence ratios on in-cylinder mixture concentration distribution,combustion characteristics,formaldehyde and unburned methanol were studied on a diesel engine retrofitted in-cylinder injection spark ignition methanol engine by coupling methanol chemical kinetics reaction mechanism with 3 DCFD software AVL-Fire.The research results show that the increase of fuel-air equivalence ratio can increase maximum in-cylinder temperature,maximum incylinder pressure and maximum heat release rate significantly and reduce the emission of formaldehyde and unburned methanol obviously.When the fuel-air equivalent ratio increases from 0.33 to 0.67,the maximum combustion pressure,maximum combustion temperature and heat release rate peak increases by 65%,72% and 51% respectively.When the fuel-air ratio exceeds0.4,the emission of unburned methanol and formaldehyde decrease sharply and mainly lie near the cylinder wall.
The influences of different fuel-air equivalence ratios on in-cylinder mixture concentration distribution,combustion characteristics,formaldehyde and unburned methanol were studied on a diesel engine retrofitted in-cylinder injection spark ignition methanol engine by coupling methanol chemical kinetics reaction mechanism with 3 DCFD software AVL-Fire.The research results show that the increase of fuel-air equivalence ratio can increase maximum in-cylinder temperature,maximum incylinder pressure and maximum heat release rate significantly and reduce the emission of formaldehyde and unburned methanol obviously.When the fuel-air equivalent ratio increases from 0.33 to 0.67,the maximum combustion pressure,maximum combustion temperature and heat release rate peak increases by 65%,72% and 51% respectively.When the fuel-air ratio exceeds0.4,the emission of unburned methanol and formaldehyde decrease sharply and mainly lie near the cylinder wall.
引文
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[15] Changming Gong,Jiajun Liu,Legao Peng,et al.Numerical study of effect of injection and ignition timings on combustion and unregulated emissions of DISI methanol engine during cold start[J].Renewable Energy,2017,112:457-465.
[16]刘方杰,刘圣华,魏衍举,等.甲醇氧化生成甲醛排放的影响因素[J].内燃机学报,2014,32(2):166-171.
[2]彭乐高,宫长明,宫宝利,等.富氧下甲醇发动机冷起动燃烧及非法规排放[J].内燃机学报,2017(5):423-428.
[3]张海燕,张仲荣,刘立东,等.汽油车尾气中醛酮类化合物排放特征的研究[J].汽车工程,2013,335(3):207-211.
[4]宫长明,宫宝利,彭乐高,等.点火时刻对甲醇发动机燃烧及非法规排放的影响[J].车用发动机,2017(6):25-29.
[5]宫长明,彭乐高,张自雷,等.DISI甲醇发动机层稀薄燃烧试验研究[J].车用发动机,2014(6):45-50.
[6] Needham J R,May M P,Doyle D M,et al.Injection timing and rate control a solution for low emissions[C].SAE Paper 900854,1990.
[7] Qu X,Gong C M,Liu J J,et al.Regulated and unregulated emissions from a DISI methanol engine under homogenous combustion and light load[J].Fuel,2015,158:166-175.
[8]Wei Y J,Liu S H,Liu F J,et al.Formaldehyde and methanol emissions from a methanol/gasoline fueled spark ignition(SI)engine[J].Energy Fuels,2009,23:3313-3321.
[9] Wu B,Wang L J,Shen X W,et al.Comparison of lean burn characteristics of an SI engine fueled with methanol and gasoline under idle condition[J].Appl Therm Eng.,2016,95:264-270.
[10] Wang X,Ge Y S,Liu L L,et al.Evaluation on toxic reduction and fuel economy of a gasoline direct injection(GDI)powered passenger car fueled with methanol gasoline blends with various substitution ratios[J].Appl Energy,2015,157:134-143.
[11]汪洋,王静,史春涛,等.甲醇发动机排放特性的研究[J].内燃机学报,2007,25(1):73-76.
[12] Grotheer H H,Kelm S,Driverh S T.Elementary reactions in the methanol oxidation systerm[J].Physical Chemitry Chemical Physics,1992,96:1360-1369.
[13] ZHEN X D,WANG Y.Numerical analysis of knock during HCCI in a high compression ratio methanol engine based on LES with detailed chemical kinetics[J].Energy Conversion and Management,2015,96:188-196.
[14] Changming Gong,Legao Peng,Fenghua Liu.Modeling of the overall equivalence ratio effects on combustion process and unregulated emissions of an SIDI methanol engine[J].Energy,2017,125:118-126.
[15] Changming Gong,Jiajun Liu,Legao Peng,et al.Numerical study of effect of injection and ignition timings on combustion and unregulated emissions of DISI methanol engine during cold start[J].Renewable Energy,2017,112:457-465.
[16]刘方杰,刘圣华,魏衍举,等.甲醇氧化生成甲醛排放的影响因素[J].内燃机学报,2014,32(2):166-171.