一种改进的柴油机冷启动热力参数计算模型

An Improved Calculating Model for Thermodynamic Parameters of Diesel Engines under Cold Starting Conditions

为了提高柴油机冷启动过程中缸内燃气压缩温度的计算精度,确保其能达到着火温度,根据热力学定律,综合考虑柴油机冷启动过程中工质压缩时的泄漏、热量的损失以及余隙容积等参数,对柴油机冷启动热力过程进行了详细的分析和推导,得出了一种具有普遍规律的新的数学模型.模型应用结果表明,随着相对余隙容积的增加,最终压缩温度呈非线性降低的趋势,当实际压缩比为20以及相对余隙容积为0.05时,和不考虑相对余隙容积而仅考虑气体泄漏、热量损失的情况相比,其最终压缩温度差值最大可达到43℃.

In order to improve the calculating accuracy of the temperature of the compressed gas in cylinder of diesel engine and to ensure that it can reach the ignition temperature under cold starting process, its thermodynamic process under cold starting conditions was analyzed and derived according to the law of thermodynamics, considering the leakage of air, the heat loss and the clearance volume, and a universal significant mathematics model was obtained. Simulation results have shown that the final temperature of the compressed gas has a trend to reduce nonlinearly as the relative clearance volume increases. Compared with the case not considering the relative clearance volume but only considering the leakage of air and the heat loss, the biggest difference of the final temperature of the compressed gas can reach 43 ℃ when the actual compressed ratio is 20 and the relative clearance volume is 0.05.