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首页> 外文期刊>Proceedings of the Institution of Mechanical Engineers, Part D. Journal of Automobile Engineering >Opposing effects of recirculated gases during cranking on cold start of diesel engines
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Opposing effects of recirculated gases during cranking on cold start of diesel engines

机译：启动过程中再循环气体对柴油机冷启动的相反影响

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摘要

The effect of recirculating engine-out gases into the intake manifold on the cold start of direct-injection diesel engines is investigated. Two types of recirculation are examined. The first is low-pressure recirculation of engine-out gases into the intake manifold where their rate is controlled by a gas recirculation (GR) valve installed between the exhaust and intake manifold. The second is high-pressure recirculation by restricting the flow of the engine-out gases using a butterfly (BF) valve, installed in the exhaust system after the turbocharger to increase the back pressure and the rate of recirculated gases. Since there is no combustion during cranking, these gases contain evaporated hydrocarbons and partial oxidation products, mostly formaldehyde (HCHO). Experimental investigations on a four-cylinder direct-injection diesel engine indicated that high rates of cranking gas recirculation (CGR) increase the ignition delay and lengthen the cranking period. Since higher concentrations of hydrocarbons (HC) are expected to enhance the autoignition process, it is suspected that the recirculated HCHO would have an opposite effect. These opposing effects are investigated using the ChemKin diesel cycle simulation model. The model results demonstrated the effect of HCHO on slowing the autoignition and combustion reactions.
机译：研究了将发动机排出的气体再循环到进气歧管中对直喷柴油机冷启动的影响。检查了两种类型的再循环。首先是发动机排出的气体进入进气歧管的低压再循环，其速度由安装在排气歧管和进气歧管之间的气体再循环（GR）阀控制。第二种是高压再循环，通过使用蝶阀（BF）限制发动机排出的气体流量，该蝶阀安装在涡轮增压器之后的排气系统中，以增加背压和再循环气体的比率。由于在启动过程中没有燃烧，这些气体包含蒸发的碳氢化合物和部分氧化产物，主要是甲醛（HCHO）。在四缸直喷式柴油发动机上进行的实验研究表明，较高的起动气再循环率（CGR）会增加点火延迟并延长起动时间。由于预期更高浓度的碳氢化合物（HC）会增强自燃过程，因此怀疑再循环的HCHO会产生相反的作用。使用ChemKin柴油循环仿真​​模型研究了这些相反的影响。模型结果证明了HCHO对减慢自燃和燃烧反应的影响。

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