稀燃天然气掺氢发动机循环变动的试验研究  

Experimental Study on Cycle-by-cycle Variations in Lean-burn Natural Gas Engine with Hydrogen Enrichment

作　　者：马凡华[1] 江龙[1] 丁尚芬[1] 王明月[1] 王业富[1] 赵淑莉[1] 

机构地区：[1]清华大学汽车安全与节能国家重点实验室,北京100084

出　　处：《机械工程学报》2010年第6期21-26,共6页Journal of Mechanical Engineering

基　　金：国家高技术研究发展计划资助项目(863计划;2006AA11A1B7)

摘　　要：对火花点火天然气发动机而言,稀燃是提高发动机燃油经济性和降低发动机排放的一种有效途径,但稀燃导致的循环变动是拓宽稀燃极限的一个主要限制因素,在天然气中掺混氢气作为燃料,可解决稀燃工况下循环变动过大的问题。为了研究掺氢对发动机循环变动影响,选取纯天然气和掺氢体积比为20%的天然气掺氢燃料,在6缸进气道喷射增压稀燃天然气发动机上进行不同点火提前角和空燃比工况下的试验研究。通过对缸内压力特性参数、燃烧特性参数以及排放数据的分析,结果表明:掺氢可有效降低发动机最高压力循环变动和平均指示压力循环变动,在稀燃情况下效果更为明显;掺氢可降低火焰发展期和燃烧持续期及其循环变动;在稀燃工况下,掺氢对控制发动机NOx及未燃HC排放有利。Lean burn is accepted as an effective approach to simultaneously improve spark ignition engine＇s thermal efficiency and decrease exhaust emissions for natural gas engines.The cycle-by-cycle variation （CCV） is a main limiting factor in expending lean burn limit.Hydrogen addition is thought to be an ideal approach to tackle the problem.An experimental study aimed at examining the effects of hydrogen addition on cycle-by-cycle variation in an SI engine is conducted on a 6-cylinder throttle body injection turbocharged natural gas engine fueled with pure natural gas and 20% hydrogen enriched compressed nature gas（HCNG） in volume.The experiment is conducted under various conditions including different ignition timings and air fuel ratios.The in cylinder pressure data,combustion characteristics and emissions are analyzed.The results show that coefficient of variation （CoV） in both maximum pressure pmax and indicated mean effective pressure （IMEP） can be reduced by hydrogen addition and that positive effect will be more obvious as the engine is further leaned out.The duration of flame development and propagation as well as the CCVs in flame propagation duration can be simultaneously reduced by hydrogen addition.Hydrogen addition is also proved to be good to the control of emission of NOx and unburned HC.

关 键 词：天然气掺氢 循环变动 氢气 燃烧持续期 排放 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程]