不同米勒循环对沼气机燃烧性能影响及优化研究  

Effects of Different Miller Cycles on Combustion and Performance of Biogas Engines

作　　者：苏展望 黄永仲[2] 赵华 裴毅强[1] 曾志龙[2] 莫员[2] 王家祥[2] 祝传艮 SU Zhanwang;HUANG Yongzhong;ZHAO Hua;PEI Yiqiang;ZENG Zhilong;MO Yuan;WANG Jiaxiang;ZHU Chuanyin(School of Mechanical Engineering of Tianjin University,Tianjin 300072,China;Guangxi Yuchai Machinery Co.,Ltd.,Yulin 537005,Guangxi,China;China North Engine Research Institute,Tianjin 300400,China)

机构地区：[1]天津大学机械工程学院,天津300072 [2]广西玉柴机器股份有限公司,广西玉林537005 [3]中国北方发动机研究所,天津300400

出　　处：《机械科学与技术》2023年第10期1583-1591,共9页Mechanical Science and Technology for Aerospace Engineering

基　　金：国家自然科学基金项目(51376202);内燃机燃烧学国家重点实验室开放研究课题项目(K2017-10)。

摘　　要：为了研究不同米勒循环对大功率沼气发动机在额定工况的燃烧和性能的影响,基于一台1.15 MW增压型沼气发动机及其仿真模型,通过变化进气门关闭正时,将沼气发动机由奥托循环改为不同米勒循环。仿真研究结果表明:在沼气发动机输出目标功率相同的情况下,随着早米勒的提前和晚米勒的推后,其缸内最大燃烧压力、最高燃烧温度、单缸排气温度、燃油消耗率及氮氧化物排放均降低明显,这表明早米勒循环和晚米勒循环对沼气发动机的燃烧和性能提升有较好的效果;随着早米勒的提前和晚米勒的推后,为了保证输出相同的功率,其增压压力需要提高,但其充气效率明显下降;随着晚米勒的加强,进气门关闭时刻进气倒流现象明显,容易出现进气回火现象,早米勒在进气门关闭时刻未发生任何进气倒流现象;相比晚米勒,早米勒更好的适宜预混增压型沼气发动机进气混合需求;所研究机型在ML-70时刻比原ML0时刻,其优点是爆发压力、燃气消耗率、氮氧化物排放分别下降3.74%、2.49%、23.58%,达到了降低爆震、提高效率、减小排放的目标。In order to study the effects of different miller cycles on the combustion and performance of a high-power biogas engine on different conditions,based on the 1.15 MW supercharged biogas engine and its simulation model,the Otto cycle of the biogas engine was changed into different miller cycles by changing the timing of inlet valve closing.Simulation results show that the biogas engine's power output reaches the same target,as the early miller cycle gets earlier and the late miller cycle gets later.The maximum combustion pressure,maximum combustion temperature in the cylinder,its exhaust temperature,fuel consumption rate and nitrogen oxide emissions are reduced obviously.This suggests that the early miller cycle and late miller cycle of the gas engine's combustion and performance are improved.With the advance of the early miller cycle and the delay of the late miller cycle,in order to ensure the same output power,their pressure needs to be increased,but the charging efficiency obviously decreases.With the strengthening of the late miller cycle,the inlet backflow phenomenon occurs when the intake valve is closed,and the inlet backflow phenomenon easily occurs.No inlet backflow phenomenon occurs when the intake valve of the early miller cycle is closed.Compared with the late miller cycle,the early miller cycle is more suitable for the intake mixture demand of a premixed and supercharged gas engine.The explosion pressure,gas consumption rate and nitrogen oxide emission of the miller cycle studied in this paper decrease by 3.74%,2.49%and 23.58%respectively,thus reducing its detonation and emissions and improving its efficiency.

关 键 词：沼气发动机 米勒循环 燃烧 性能 排放 

分 类 号：TK421[动力工程及工程热物理—动力机械及工程]