过量空气系数对柴油/甲醇RCCI发动机非常规排放特性的影响  

Effects of excess air coefficient on non-regulated emissions of diesel/methanol RCCI engines

作　　者：黄粉莲[1] 田茂盛 万明定 申立忠 雷基林[1] Huang Fenlian;Tian Maosheng;Wan Mingding;Shen Lizhong;Lei Jilin(Yunnan Key Laboratory of Internal Combustion Engines,Kunming University of Science and Technology,Kunming 650500,China)

机构地区：[1]昆明理工大学云南省内燃机重点实验室,昆明650500

出　　处：《农业工程学报》2021年第8期52-61,共10页Transactions of the Chinese Society of Agricultural Engineering

基　　金：云南省科技计划项目(2019FB073);国家自然科学基金项目(52066008)。

摘　　要：为探究柴油/甲醇反应活性控制压燃(Reactivity Controlled Compression Ignition,RCCI)发动机非常规排放特性及影响机理,该研究对某高压共轨柴油机进气歧管进行改造,搭建了柴油/甲醇双燃料RCCI发动机专用试验台架,系统研究了不同甲醇替代率、过量空气系数对发动机非常规排放物的影响规律。结果表明:最大转矩转速(2 000 r/min)、不同负荷工况下,随甲醇替代率增大,柴油/甲醇RCCI发动机甲醇、甲醛、芳香烃碳氢化合物和SO_2排放量升高,非甲烷总烃、CO_(2)排放降低;25%负荷、甲醇替代率从0%增加到15%,CO_(2)排放量降低4.5%;100%负荷、30%甲醇替代率时,CO_(2)排放量较纯柴油模式减少6.8%。随过量空气系数减小,未燃甲醇、甲醛、非甲烷总烃和SO_2排放量降低,CO_(2)排放升高;25%负荷下,过量空气系数从3.48减小到3.05,5%、10%、15%替代率下甲醇排放量分别降低16.9%、12.7%和14.5%,甲醛排放量分别降低8.8%、10.8%和10.5%,非甲烷总烃排放量平均下降75%;100%负荷下,过量空气系数从1.6减小到1.38,10%、20%、30%替代率下甲醇排放量分别降低45.6%、45.9%和43.9%,非甲烷总烃排放分别降低18.2%、27.3%和60%,甲醛排放量平均减少34.4%;高负荷下芳香烃碳氢化合物随过量空气系数的减小而升高,低负荷下变化不明显;RCCI模式下,碳氢化合物的主要成分是未燃甲醇和甲醛,适当关小节气门开度,减小过量空气系数,对降低非常规污染物排放有利。外特性工况下,随发动机转速增加,未燃甲醇、非甲烷总烃、二氧化碳排放降低,甲醛排放增多;不同转速下随着甲醇替代率增加,非甲烷总烃和二氧化碳排放降低,未燃甲醇和甲醛排放量增加。研究结果可为柴油/甲醇双燃料RCCI发动机非常规排放物控制奠定理论基础。Reactivity-Controlled Compression Ignition(RCCI)is widely expected as a promising dual fuel low-temperature combustion(LTC)strategy in recent engines.The potential strategy can control the in-cylinder fuel reactivity for the low NO and Particulate Matter(PM)emissions with high thermal efficiency.This study aims to investigate the effects of methanol fraction and excess air coefficient on the non-regulated emissions of diesel engines in RCCI mode under different operating conditions.A bench test was performed on a modified 4-cylinder high-pressure common-rail diesel engine under RCCI combustion.The results showed that the total hydrocarbon emissions increased sharply with the rise of methanol substitution rate,while decreased with the increase of load at 2000 r/min.The unburned methanol accounted for about 90%of total hydrocarbons(THC)emissions under the methanol/diesel dual fuel.The emissions of methanol,formaldehyde(HCHO),aromatic hydrocarbons(AHC),and sulfur dioxide(SO2)increased,whereas,the emissions of non-methane hydrocarbons(NMHC)and carbon dioxide(CO_(2))decreased,as the methanol substitution rate increased.The CO_(2) emission reduced by 4.5%as the methanol substitution rate increased from 0%to 15%at 25%load,while dropped by 6.8%in the methanol proportion from 0%to 30%at 100%load.The emissions of unburned methanol,formaldehyde,NMHC and SO2 decreased,while the CO_(2) emission increased at different load rates with the decrease of excess air coefficient.Under 25%load,the emission of unburned methanol decreased by 16.9%,12.7%,and 14.5%,while the emissions of formaldehyde reduced by 8.8%,10.8%,and 10.5%,and the NMHC emissions reduced by 66.7%and 83.3%with 5%,10%and 15%methanol substitution rate,as the excess air coefficient was reduced from 3.48 to 3.05.Under 100%load condition,the methanol emissions reduced by 45.6%,45.9%,and 43.9%,and the formaldehyde emissions decreased by 36.5%and 33.3%,while the NMHC emissions dropped by 18.2%,27.3%,and 60%with 10%,20%,and 30%methanol,as the excess air coefficient decreas

关 键 词：发动机 燃烧 柴油 甲醇 过量空气系数 非常规排放物 

分 类 号：TK422[动力工程及工程热物理—动力机械及工程] TK421.5