柴油机燃用柴油-二甲醚混合燃料对其性能及排放的影响

二甲醚是一种适用于压燃直喷式柴油机的很具潜力蹬代用燃料，除了无碳烟排放的重要特点以外，和柴油相比二甲醚还具有较好的燃烧性能，较低的自然温度和较好的雾化特性，但二甲醚较差的润滑性会带来一些问题，例如磨损和泄漏，这是一个很难处理的问题。文中对直喷式柴油机燃用二甲醚柴油混合燃料进行了实验研究，对二甲醚重量比分别为0％（纯柴油），10％和20％的混合燃料进行了评测，并测量了发动机的性能和排放，结果表明，与纯二甲醚相比，柴油－二甲醚混合燃料具有较高的润滑性能，及和纯柴油相比，具有较好的喷射雾化性能，同时发现发动机在燃用柴油时的工作特性和燃用柴油－二甲醚混合燃料时的工作特性是可以比较的，当混合燃料中的二甲醚的比例为20％，NOx，碳烟和CO的排放量分别降低了11％，42％和29％，和燃用柴油相比，HC排放量在轻载时较高，在重载时较低。

The Effects of Diesel-DME Blends on Performance and Emissions of DI Diesel Engine

Dimethyl ether (DME) is a promising and excellent alternative fuel for compression ignition DI diesel engines. In addition to the significant merit of no soot emission, DME would be of better ignition quality, lower autoignition temperature and better atomization compared to diesel fuel. However, some problems arise from the poor lubricity of DME. For example, breakdown of film bearing between needle and sleeve of the injector can lead to mechanical wear and leakage, a problem that is hard to tackle. In this paper, diesel fuel blended with DME (diesel-DME blends) are experimentally investigated in a DI diesel engine. Blends including zero weight percent DME (pure diesel fuel), 10% and 20% weight DME are evaluated. The engine performance and the exhaust emissions are measured. The results show that diesel-DME blends have a higher lubricity compared with pure DME and a better injection spray compared with pure diesel fuel. The performance of engine operated on diesel fuel and diesel-DME blends are found to be comparable. About 11% NOx, 43% smoke and 29% CO emission reductions could be achieved with 20%DME blends operation. HC emission is higher at light duty and lower at heavy duty compared with diesel fuel.