冷却液温度为边界条件的柴油机起动试验研究

为了研究冷却液温度对柴油机起动过程初期燃烧不稳定性及排放的影响规律,在一台单缸直喷式柴油机上,利用缸压和单循环采样测试系统对柴油机起动初期单个工作循环的燃烧和排放进行了试验研究。结果表明:冷却液温度是影响柴油机起动过程不稳定的重要因素之一。较低的冷却液温度导致柴油机起动初期燃烧不稳定性增加,失火和不完全燃烧循环较多,从而导致HC排放升高,而且冷却液温度低造成的滞后燃烧会产生较高的CO排放。冷却液温度升高后,失火循环消除,同时着火延迟期明显缩短,最高燃烧压力升高,HC和CO排放显著降低,NOx排放升高,表明燃烧状况改善。

Experimental Study on Start of Diesel Engine under Different Boundary Conditions of Coolant Temperature

For researching the effects of coolant temperature on combustion stability and emissions during the initial of start,the experiment on single working cycle combustion and emissions was carried out on a single cylinder direct injection diesel engine with considering cylinder pressure and using single cycle sampling test system.The results indicate that the coolant temperature is one of the important factors which affect the combustion stability.The lower coolant temperature leads to the increase of the combustion instability and even frequent the misfiring and incomplete combustion which increase the emission of HC during the initial of start,and the lagging combustion caused by the low coolant temperature will bring about the high emission of CO.With the increase of coolant temperature,the misfiring cycle disappears,the delay time of ignition shortens,the maximum combustion pressure rises,the emissions of HC and CO reduce notably,and the emission of NOx increases.These phenomena indicate that the combustion state has been improved.