柴油机燃用二甲醚喷射与燃烧的试验研究

研究了2135型柴油机燃用二甲醚日寸的喷射与燃烧特性。测试了嘴端油管压力、针阀升程、缸内压力、氮氧化物排放等参数，计算了燃烧率和累计燃烧率。试验结果表明，该燃料的喷射与燃烧过程明显不同于柴油。二甲醚的油管压力升高率和压力峰值低，喷射滞后期及其负荷依赖性很大；相应地，其着火点迟后，着火点的负荷依赖性也很大；滞燃期短；缸内最高燃烧压力和压力升高率低；扩散燃烧快速。柴油机燃用二甲醚可大幅降低氮氧化物排放，并实现无烟、低噪声燃烧。

Experimental Investigation on Injection and Combustion of Dimethyl Ether Fueled Diesel Engine

The injection and combustion characteristics of dimethyl ether (DME) were experimentally investigated on a naturally aspirated, high speed D.I. diesel engine with a pump line nozzle fuel system. As DME is easy to atomize and evaporate, the nozzle opening pressure was lowered. Such parameters as line pressures at nozzle side, needle lift, in cylinder pressure and NO x emission were measured and the combustion rate and accumulated combustion rate were calculated. The study demonstrates that DME has different injection and combustion processes from diesel fuel. The line pressure rise rate and peak line pressure with DME are very low, and the injection delay increases more notably with load decrease. Correspondingly, DME ignites later than diesel fuel, and the ignition point depends on load more obviously than that of diesel fuel. With DME, the ignition delay is short, the maximum in cylinder pressure and pressure rise rate are significantly low, and the diffusion combustion duration is short. Diesel engine operating on DME instead of diesel fuel can considerably reduce NO x emission and achieve zero smoke and low noise combustion.