燃料设计改善发动机燃烧和排放的研究(2)--对柴油机燃烧与排放影响的分析

根据本文第一部分提出的含氧燃料设计思想与方法，以碳酸二甲脂(DMC)为例，研究了较宽比例范围内的DMC柴油混合燃料对柴油机的燃烧与排放特性的影响。在一台高速柴油机上测量了各种混合燃料在最高转速下的负荷特性和速度特性，以及主要工况下的示功图，并对燃烧特性进行了分析。试验结果发现：在柴油中加入一定比例的DMC后，由于物性参数的变化和喷雾特性的改善，混合燃料能够改善柴油机的燃烧与排放——热效率得到明显的提高，尤其在低转速下改善显著；烟度和氮氧化物排放同时降低，外特性线上的一氧化碳降低，碳氢排放仍然很低。对燃烧特性的分析发现：DMC柴油混合燃料的着火延迟延长，燃烧速率加快，燃烧持续期缩短。

Fuel Design Concept for Improvement of the Engine Combustion and Emissions (2)--Effect of Fuel Design Concept on Heat Release Rate and Emissions of Diesel Engine

Based on the Part 1, this article presented combustion characteristics and emissions of high-speed diesel engine fueled with DMC-diesel blended fuels. Engine tests were carried out on a 4-cylinder high-speed diesel engine, performance and emissions were compared, and the heat release rate was analyzed. The results showed that the combustion and emissions were improved when DMC-diesel blended fuel were used-the brake thermal efficiency increased, smoke and NO_x decreased simultaneously, CO decreased at large load, and HC emissions are very low. Combustion analysis, showed that ignition delay and, maximum heat release rate increased, while combustion duration decreased when engine fueled with DMC-diesel blended fuel.