掺混PODE对增压中冷柴油机燃烧和排放性能的影响

在一台电控共轨增压中冷柴油发动机台架上,燃用纯柴油以及柴油中分别掺混10%、20%、30%(体积比)聚甲氧基二甲醚(PODE)的混合燃料,研究了PODE对柴油发动机燃烧排放特性以及燃油经济性的影响.结果表明PODE的掺混显著影响发动机的燃烧特性:除低速大负荷工况外,PODE的掺入明显降低了预喷放热率,改善了主喷燃料的雾化性能,加大了主喷前缸内的活化成分比例,提升了主喷期间压力升高率和燃烧放热率,提高了缸内燃烧温度,缩短了燃烧持续期.在研究范围内,PODE掺混比越大,缸内燃烧最高温度越高,主喷燃料燃烧速度越快,燃烧持续期越短.排放研究结果表明,随着PODE的掺入,发动机的NO_x排放明显上升,HC排放略有下降,CO排放变化不大.PODE的掺入能明显改善发动机的燃油经济性.

Effect of PODE on Combustion and Emission Characteristics of a Turbo Charged Intercooled Diesel Engine

Abstract： The effect of polyoxymethylene dimethyl ethers (PODE) on the combustion, emission performance and fuel economy of a turbo charged intercooled common rail diesel engine was investigated, in the cases of pure diesel and diesel blended with 10%, 20%, 30% PODE respectively. The results showed that the added PODE affects the engine combustion characteristic significantly. Except for the low speed and light duty engine mode, the blend of PODE decreases the heat release rate of the pre injection fuel, improves the atomozation performance of the main injection fuel, increases the active ingredients in combustion chamber before the main fuel injection, increases the pressure rising rate and heat release rate as well as the in cylinder mean temperature in the main fuel injection period, and shortens the combustion duration. Under test conditions, with the increasing of blended PODE ratio, the in cylinder maxium temperature and the fuel combustion speed of the main injection fuel increases while the combustion duration decreases. The emission investigation showed that with the mixtured PODE, the NOx emission increases, the HC emission decreases slightly but the CO emission remains unchanged. The fuel economy is improved by adding PODE.