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废气再循环系统参数对柴油机燃烧特征的影响研究
许广举,赵洋,李铭迪,陈庆樟,李广华,等
作者单位E-mail
许广举 常熟理工学院汽车工程学院 常熟 215500 xuguangju@cslg.cn 
赵洋 常熟理工学院汽车工程学院 常熟 215500  
李铭迪 常熟理工学院汽车工程学院 常熟 215500  
陈庆樟 常熟理工学院汽车工程学院 常熟 215500  
李广华 常熟理工学院汽车工程学院 常熟 215500  
摘要:
为进一步优化柴油机燃烧过程,减少燃烧污染物排放。围绕EGR(exhaust gas recirculation,废气再循环技术)废气组分和废气温度等系统参数对柴油机燃烧特征的影响机制,采用试验与模拟相结合方法,分别研究了通入废气、N2、CO2时以及不同EGR废气温度时对柴油机燃烧过程的影响,阐明了燃烧关键中间产物的生成规律。研究结果表明,通入CO2时,柴油机的缸内最大爆发压力和放热率峰值最低,滞燃期最长,燃烧持续期最短,OH、H2O2、CH2O和CO等关键中间组分的生成规律与通入N2时相反。通入N2时,柴油机的缸内最大爆发压力和放热率峰值最高,滞燃期最短,燃烧持续期最长;且通入N2时,OH自由基的峰值最高,形成时刻最早,H2O2、CH2O自由基以及CO的峰值均有所降低且形成时刻提前。随着废气温度增加,缸内最大爆发压力降低,放热率曲线由单峰向双峰分布发展,放热率峰值有较大幅度降低,滞燃期缩短,燃烧持续延长,缸内OH、H2O2、CH2O自由基以及CO的峰值均有所降低,且生成的区域范围变窄。废气成分中,CO2对燃烧过程和关键中间产物的影响最大,是阻滞燃烧反应的主要气体成分,通过控制EGR废气成分和温度可以有效改善柴油机燃烧过程,拓宽EGR技术的工况使用范围。
关键词:  废气再循环  柴油机  燃烧  温度  气体成分
DOI:
分类号:TK464
基金项目:江苏省自然科学青年基金项目(BK20160406),江苏省高校自然科学研究面上项目(15KJB470001);苏州市应用基础研究项目(SYG201515)
Xu Guangju, Zhao yang, Li Mingdi , Chen Qingzhang , Li Guanghua
xuguangju,et al
Abstract:
In order to optimize the combustion process of diesel engine and reduce the emission of pollutants, the effects of exhaust gas composition and temperature of EGR on combustion characteristic of diesel engine are systematic researched by the way of combing experiments and simulations in this paper, especially the influence of N2, CO2 and different EGR exhaust gas temperature on combustion process of diesel engine. The results show that, comparing with exhaust gas and N2, the engine can obtain the maximum cylinder explosion pressure, the lowest heat release rate peak, the longest combustion delay period and the shortest combustion duration by adding CO2 gas. The engine can obtain the maximum cylinder explosion pressure,the maximum heat release rate, the minimum combustion delay period and the longest combustion duration by adding N2 gas. Comparing with EGR, the OH free radical which is formed first reached the highest peak with the single inlet of N2, where as the data of peaks of H2O2, CH2O and CO free radicals is reduced slightly as well as formations are moved forward. When the engine introduces CO2 gas, the formation of key intermediate components such as OH, H2O2, CH2O and CO is contrary to the N2 gas. When the exhaust gas is introduced into the engine, the combustion characteristic parameters and the critical intermediate component generation and generation time of the diesel engine are between N2 and CO2. With the increase of EGR exhaust temperature, the maximum cylinder explosion pressure decreases, the heat release rate curve develops from a single peak to double peak, the peak value of heat release rate decreases greatly, the ignition delay period is shortened, the combustion duration is prolonged, the peak values of OH, H2O2, CH2O, free radical and CO were decreased and the range of the generated region was shortened. The influence of CO2 on the combustion process and the key intermediate product is greater than N2, CO2 is the main block of gas combustion reaction components, the combustion process of diesel engine can be improved effectively and the working range of EGR can be widened by controlling the composition and temperature of EGR exhaust gas.
Key words:  exhaust gas recirculation  diesel engine  combustion  temperature  gas composition