天然气发动机燃烧影响因素分析

李玉帅，赵令辉，潘永传，韩雨，李哲

潍柴动力股份有限公司，山东 潍坊  261061

摘要：为提高发动机的热效率和降低排放，采用仿真分析及台架试验，分析挤流比、涡流比、米勒强度、点火能量和废气再循环（exhaust gas recirculation，EGR）率5个因素对某天燃气发动机性能的影响。结果表明：发动机挤流比为0.46时，燃烧速率最快、热效率最高、CH₄排放最低，但NO_x排放较高；大涡流比可使燃烧更快速充分，发动机热效率更高，尤其在转速较低时影响更明显；米勒强度越大，压缩终点缸内环境温度越低，燃烧速率越慢，但由于压缩功降低，热效率略有下降，THC排放大幅升高，NO_x排放大幅降低；提高点火能量，热效率升高，NO_x排放升高，THC排放降低，低负荷条件下影响更明显；EGR率越大，燃烧温度越低，传热和排气损失越少，热效率升高，NO_x排放降低，THC排放升高。

关键词：当量燃烧；燃烧分析；经济性；排放

Analysis of influencing factors on combustion of natural gas engine

LI Yushuai，ZHAO Linghui，PAN Yongchuan，HAN Yu，LI Zhe

Weichai Power Co., Ltd., Weifang 261061, China

Abstract：In order to improve the thermal efficiency and reduce the emission of the engine, the simulation analysis and the bench test are adopted, the effects of extrusion ratio, eddy ratio, miller strength, ignition energy and exhaust gas recirculation(EGR) rate on the performance of a natural gas engine are analyzed. The results show that when the extrusion ratio is 0.46, the combustion rate is the fastest, the thermal efficiency is the highest and the CH₄ emission is the lowest, but the NO_x emission is the highest. The higher the miller intensity is, the lower the ambient temperature is, the slower the combustion rate is, the lower the compression power and the lower the thermal efficiency is, while the higher the THC emission is. With the increasing ignition energy, the thermal efficiency increases as well as the NO_x emission, and the THC emission decreases. The more the EGR rate is, the lower the combustion temperature is, and the less the heat transfer and exhaust loss is, but thermal efficiency and THC emission increases is, while NO_x emission decreases.

Keywords:equivalent combustion;combustion analysis;economy;emission