LPG掺混比对DME-柴油预混压燃发动机性能影响的试验研究

Effects of LPG Blending Ratio on Performance of DME-Diesel Premixed Charge Compression Ignition Engine

针对二甲醚(DME)-柴油双燃料预混压燃发动机在DME预混量较大工况下存在的爆震等问题,在一台2105柴油机上研究了液化石油气(LPG)掺混比对DME-柴油双燃料发动机燃烧特性、燃油经济性以及排放特性的影响。随LPG掺混比(f_L)增大,双燃料发动机表现出如下性能变化趋势:DME低温、高温反应阶段放热率峰值减小,柴油扩散燃烧阶段放热率峰值增大,3个阶段放热率峰值相位均滞后;缸内最大燃烧压力和最高燃烧温度降低;压力升高率曲线滞后,f_L=50%时最大压力升高率较高;有效热效率η_(et)逐渐降低;NO_x排放呈现降低趋势。f_L为20%和33%时,颗粒数量浓度高于预混纯DME工况;f_L为50%时,颗粒数量浓度与预混纯DME工况相当。

In order to solve the knock problem of DME-diesel dual fuel premixed charge compression ignition engine with a great premixed mass of DME,the effects of LPG blending ratio on combustion characteristics , fuel economy and emission characteristics were experimentally investigated on a 2105 diesel engine.The results show that the peak of heat release rate decreases in the stage of DME low temperature and high temperature reaction and increases in the stage of diesel diffusion combustion and its correspondent phases postpone in the three stages with the increase of LPG blending ratio/L.The maximum incylinder pressure and temperature decrease.The rising edge of pressure rise rate curve delays and the maximum pressure rise rate reaches the highest when the blending ratio/L is 50%.The effective thermal efficiency decreases and NOx emission shows a decreasing trend.Compared with premixing with pure DME, the particle number emissions are different which are higher when/L is 20%or 33%and are the same when/L is 50%.