发动机燃用生物柴油-柴油-乙醇混合燃料的性能试验

摘要

In order to reduce the emissions of diesel engine fueled with biodiesel-diesel blended fuel mixed at medium propor-tion,the performance differences between biodiesel-diesel blended fuel and pure diesel fuel were analyzed and the influences of ethanol blending ratio on economy,power and emission characteristics were studied by mixing the blended fuel with 10% and 20% of ethanol respectively under different loads of 1 400 r/min and 2 000 r/min.The results show that the brake specific fuel consumption and NO xemission of biodiesel-diesel blended fuel increase and the power and soot emission decrease.With the in-crease of ethanol blending ratio,the brake specific fuel consumption of biodiesel-diesel-ethanol blended fuel increases.The ef-fective thermal efficiency decreases at low load due to the influence of latent heat from ethanol vaporization,is little influenced at medium load,and increases at high load due to the high oxygen content of ethanol.The maximum power of engine decreases with the increase of ethanol blending ratio under full load conditions of 1 400 r/min and 2 000 r/min.With the increase of etha-nol content in biodiesel-diesel-ethanol blended fuel,the soot,NO xand CO emissions decrease gradually under different loads. In addition,the HC emission increases obviously due to the high latent heat caused by strong vaporization of ethanol at low load.%为了降低柴油机燃用中等比例生物柴油-柴油混合燃料的污染物排放,在1400 r/min和2000 r/min不同负荷条件下,首先对比分析了发动机燃用生物柴油-柴油混合燃料与纯柴油的性能差异,然后在中等比例的生物柴油-柴油混合燃料中分别掺混10% 和20%(体积比)的无水乙醇,测定了乙醇掺混比对发动机经济性、动力性和排放特性的影响.结果表明:与纯柴油相比,生物柴油-柴油混合燃料的有效燃油消耗率上升,动力性略有下降,炭烟排放降低,而NO x排放升高.随着乙醇掺混比的增大,生物柴油-柴油-乙醇混合燃料的有效燃油消耗率升高,小负荷时受乙醇汽化潜热的影响导致有效热效率下降,中等负荷时乙醇对有效热效率的影响不大,而大负荷时乙醇的高含氧量能够提高发动机的有效热效率.1400 r/min和2000 r/min全负荷条件下,发动机的最大功率随乙醇掺混比的增大而下降.在不同负荷条件下,随着生物柴油-柴油-乙醇混合燃料中乙醇掺混比的增大,发动机的炭烟、NO x和CO排放逐渐降低,小负荷时乙醇的高汽化潜热导致HC排放明显升高.