直喷发动机燃油喷雾撞击壁面形成油膜,导致燃烧效率降低,颗粒物排放增加.伴随撞壁的动态传热过程对油膜蒸发具有重要影响.本文针对正戊烷、甲醇、甲醇-汽油混合燃料瞬态喷雾撞击壁面,研究了不同条件下蒸发性对燃油瞬态喷雾撞击壁面动态传热影响.结果表明,提高喷油温度可促进燃油雾化,增大喷油压力或降低喷油距离可提高液滴撞壁强度,缩短液膜存在时间.撞壁瞬态温度与热流密度动态变化特征受燃油蒸发性与喷雾条件联合影响.

本文在新标欧洲循环测试(New European Driving Cycle, NEDC)工况下,当温度为-7 ℃、相对湿度为30%时,进行新能源汽车空调热泵系统整车实验.根据车型搭建了乘员舱热负荷模型和空调系统零部件仿真模型,并建立了整车一维仿真分析模型,与实验数据进行对比.结果表明,暖风芯体、冷凝器、压缩机功耗、压缩机制热量和系统能耗仿真模型平均误差分别为1.8%、1.2%、6.5%、1.5%和3.9%.

The refrigerant flow distribution in the parallel flow microchannel evaporators is experimentally investigated to study the effect of header configuration. Six different configurations are tested in the same evaporator by installing insertion device and partition plate in the header to ensure the consistency of the other structure parameters. The results show that the uniformity of refrigerant flow distribution and the heat transfer rate are greatly improved by reducing the sectional area of header. The heat transfer rate can increase by 67.93% by reducing the sectional area of both inlet and outlet headers. The uniformity of refrigerant flow distribution and the heat transfer rate become worse after installing the partition plate in the insertion devices and changing the inner structure of the header further.