高压缩比射流点火天然气发动机燃烧及排放特性  

Combustion and Emission Characteristics of High Compression Ratio Jet Ignition Natural Gas Engine

作　　者：赵自庆 蔡开源 王志[1] Zhao Ziqing;Cai Kaiyuan;Wang Zhi(School of Vehicle and Mobility,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学车辆与运载学院,北京100084

出　　处：《内燃机学报》2022年第1期10-19,共10页Transactions of Csice

基　　金：国家自然科学基金资助项目(51176136).

摘　　要：采用一维仿真,预测并分析了压缩比对射流点火天然气发动机烧特性规律,进一步结合台架试验研究了高压缩比下采用不同稀释策略时射流点火天然气发动机的燃烧及排放特性.结果表明:压缩比提升至17.0时,燃烧初期放热迅速,滞燃期缩短,燃烧持续期显著增加;采用纯空气稀释时,燃烧效率提高,热效率提升小于1%;CO、NO_(x)排放增加,HC排放减少;射流撞壁造成传热损失的增加以及后燃现象限制了热效率的提升;进一步引入废气再循环(EGR)后,高压缩比下缸内燃烧恶化相对严重,燃烧效率降低,HC及CO排放增加,最高指示热效率在低压缩比下达到44%.Jet ignition technology is one of the effective ignition technologies to improve the thermal efficiency of natural gas engines.1D simulation was used to predict and analyze the effects of compression ratioεon combustion characteristics in an active jet ignition compressed natural gas(CNG)engine.The combustion and emission characteristics under highεwith different dilution strategies were further investigated experimentally in a single cylinder natural gas engine bench.The results indicate that when theεis increased to 17.0,the heat release is fast at early combustion phase,the ignition delay decreases and the combustion duration increases.When adopting the pure air dilution strategy,the combustion efficiency increases but the increase of indicated thermal efficiency(ITE)is less than 1%.CO and NO_(x) emissions increase and HC emission decreases.The heat transfer loss caused by jet impingement onto the surface of combustion chamber and the post combustion limit the improvement of thermal efficiency at highε.By further introducing exhaust gas recirculation(EGR),the combustion under highεdeteriorates and the combustion efficiency decreases.The emissions of HC and CO increase,the maximum ITE of 44%is achieved atε=11.5 on bench test.

关 键 词：天然气发动机 射流点火 高压缩比 热效率 

分 类 号：TK437[动力工程及工程热物理—动力机械及工程]