为提高柴油机性能、降低排放和油耗,分析高、低压废气再循环(exhaust gas recirculation,EGR)系统的优缺点,对装配高/低压EGR系统的某 2.0L柴油机进行台架及整车试验,研究高/低压EGR系统对柴油机性能的影响.结果表明:同时匹配高/低压EGR系统并合理分配其应用可有效降低柴油机油耗及排放,相比仅匹配高压EGR系统的柴油机,高/低压EGR联合应用的柴油机油耗降低 3.1%,NOx 排放降低 3.0%,颗粒物排放降低22.2%;低压EGR可减少流经进气歧管的废气量,改善进气歧管结焦问题;在低温环境下应用EGR系统时进气系统存在结冰风险,需基于环境温度修正关闭高/低压EGR系统,避免出现因结冰导致的发动机损坏.
The effect of high/low pressure EGR system on performances of a diesel engine
In order to improve the performance of a diesel engine,optimize emissions and reduce fuel consumption,advantages and disadvantages of high/low pressure(HP/LP)exhaust gas recirculation(EGR)are analyzed.A 2.0 L diesel engine equipped with HP/LP-EGR system is tested on the bench and vehicle to study the impact of HP/LP-EGR system on diesel engine performance.The results show that fuel consumption and emissions can be effectively reduced by matching HP/LP EGR system and applying it rationally,compared with diesel engines with HP EGR system,the combined application of HP/LP-EGR system can reduce fuel consumption by 3.1%,NOx emission by 3.0%,and PM emission by 22.2%.The application of LP EGR system can reduce the amount of exhaust gas flowing through the intake manifold,thereby improving the intake manifold coking problem.The EGR system may freeze when the intake system is used in a low temperature environment.The HP/LP EGR system should be closed based on the ambient temperature to avoid engine damage caused by ice.
HP EGRLP EGRfuel consumptionemissioncokingice formation
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