柴油机燃用生物柴油的碳烟排放模拟

Simulation of Soot Emission From Diesel Engine Fueled With Biodiesel

开展柴油机燃用生物柴油时的碳烟生成量的研究,基于广安碳烟模型提出了一种计算燃用生物柴油的碳烟排放公式。以实测示功图作为输入数据,结合喷雾与空气卷吸子模型、油滴蒸发燃烧子模型、传热子模型以及广安博之碳烟子模型,建立柴油机燃用生物柴油时碳烟排放的准维预测模型,计算碳烟生成量。结果表明,十三工况的计算值与试验实测碳烟排放量吻合,该模型适用于工程上模拟含氧燃料的碳烟排放。与柴油相比,由于柴油机燃用生物柴油时着火时刻提前,较早地达到碳烟生成的触发温度,燃烧开始阶段生成碳烟增加;但是由于生物柴油属于含氧燃料,其碳烟生成峰值和最终排出量均比柴油的低大约50%。

The study on the soot emission characteristics of diesel engine fueled with diesel or biodiesel was conducted,and a predictive formula based on hiroyasu soot submodel for soot emission of the biodiesel was proposed.Based on the measured indicator diagram,a quasidimensional particulate emission model for the engine fueled with biodiesel was established by combining a fuel spray impinging and air entrainment submodel,droplet＇s evaporation and combustion submodel,the heat transfer submodel and hiroyasu soot submodel,and the in-cylinder soot mass was calculated.The results indicated that the theoretical results calculated agreed well with experimental results,and the established model was suitable for soot emission prediction of diesel engine fueled with oxygenated fuels.The ignition start of biodiesel in engine was early to reach the trigger temperature of soot formation,so soot emission increased in the initial stage of combustion.Since the oxygen concentration at combustion area was high due to the oxygenated properties of biodiesel,the peak and final emission value of soot was reduced by more than 50%compared with that of 0#diesel.