柴油/甲醇不同掺烧方式燃烧过程和排放对比分析

在不改变4B26增压柴油机结构的前提下，对柴油机气道喷射甲醇与柴油/甲醇直接混合燃料进行了燃烧过程、排放性能试验，对两种柴油/甲醇掺烧方式的燃烧过程与排放进行了分析。试验结果表明：与柴油/甲醇直接混合相比，柴油机气道喷射掺烧10%甲醇，气缸压力相差不大，缸内平均温度较低，低负荷时滞燃期较长；气道喷射甲醇大幅度降低排气温度，NOx和碳烟排放降低效果较为显著，HC和CO排放较高。与燃烧柴油相比，两种方式掺烧10%甲醇时，发动机的动力性变化不大，缸内平均温度都有所降低，滞燃期有所延长；NOx和碳烟排放降低，HC和CO排放有所增加。

Comparative Analysis of Combustion and Emissions of DI Engine Operating on Diesel/Methanol by Different Methods

The combustion process and emissions of diesel with 10% of diesel/methanol blend or 10% of port-injected methanol are studied. 4B26 turbo-charge DI engine without any change in its original structure is test at a constant speed of 2 200 r/min under the conditions of four different engine loads, which is equipped with an electrically-controlled port injection system. The result shows that the in-cylinder pressure of DI engine has no great difference in the use of diesel/methanol blend and port-injected methanol. Compared with diesel/methanol blend, the port-injected methanol gives a lower intake air temperature, contributing to a further lower exhaust temperature. The ignition delay period becomes longer at low load, and NOx and soot emissions are reduced significantly, meanwhile, HC and CO emissions are high. In both cases, compared with diesel, the maximum pressure hardly changes, the in-cylinder temperature decreases, and the ignition delay postpones at low load; NOx and soot emissions are reduced, and HC and CO emissions are increased.