PODE/乙醇双燃料共轨发动机的燃烧特性

为了实现高效清洁燃烧，在一台增压中冷电控共轨发动机上，采用进气预混乙醇燃料由缸内直喷聚甲氧基二甲醚(PODE)引燃，实现PODE/乙醇双燃料燃烧，研究了预混乙醇比例对双燃料发动机燃烧过程以及燃油经济性的影响。结果表明，在平均有效压力pme=038 MPa时，随着乙醇比例增加，双燃料燃烧相位推迟，最大燃烧压力降低，预混放热量及放热率增加；在pme=100 MPa时，〖JP3〗预混乙醇发生自燃，最大缸内燃烧压力急剧增加，燃烧持续期延长，CA50靠近上止点，振动强度也增大，但有效热效率显著提高，最大可以达到406%。在pme=038 MPa〖JP〗时，双燃料能够同时降低NOx和碳烟排放量，改变了它们之间的trade off关系。合理控制预混乙醇比例可以改善双燃料发动机的燃油经济性，并降低污染物的排放量。

Experimental Study on Combustion Characteristics of Common-Rail Engine Fueled with PODE/Ethanol Dual Fuel

In order to achieve high effectiveness and clean combustion, polyoxymethylene dimethyl ethers (PODE)/ethanol dual fuel combustion was conducted on a turbocharged inter cooling common rail engine, in which the intake premixed ethanol fuel was ignited by the direct injection PODE. The effects of premixed ethanol ratio on the combustion process and fuel economy of the dual fuel engine were studied. Experimental results show that at brake mean effective pressure pme=038 MPa, the combustion phase of dual fuel is delayed with the increase of ethanol ratio, the maximum combustion pressure decreases, the amount of premixed heat release and the maximum heat release rate increases. At pme=100 MPa, the premixed ethanol is prone to spontaneous combustion. The maximum combustion pressure increases sharply, the combustion duration extends, CA50 gets close to the top dead center, and the variation of ringing intensity increases with the increase of ethanol ratio. At the same time, the brake thermal efficiency increases and it has a maximum value of 406%. At pme=038 MPa, dual fuel can simultaneously reduce NOx and soot emissions, and the trade off relationship between them has been changed. Reasonable control of premixed ethanol ratio can improve the fuel economy of the dual fuel engine and reduce its pollutant emissions.