宽馏分燃料对柴油机低温燃烧影响的试验研究

Experimental Study on Effects of Wide-Distillation Fuel Properties on Low Temperature Combustion in a Diesel Engine

通过将汽油和柴油掺混配制成不同比例的宽馏分燃料,在一台单缸柴油机上进行宽馏分燃料对柴油机低温燃烧影响的试验研究.结果表明,十六烷值是影响柴油机低温燃烧的主要因素,挥发性对燃烧特性影响相对较小;较高汽油比例的宽馏分燃料由于十六烷值降低更明显、滞燃期延长,可以较明显改善低温燃烧的碳烟排放.在汽油比例较高时,由于挥发性提高较明显,能够对碳烟排放起到一定的改善作用.在宽馏分燃料中随着汽油比例的增加,燃烧速度加快,指示热效率略有提高.宽馏分燃料对NOx、CO和THC排放的影响比较小,在高EGR率条件下可以实现超低NOx排放,但此时CO与THC排放问题有待解决,并且汽油比例较高的宽馏分燃料THC排放更高.

Experiments were conducted to evaluate the effects of wide-distillation fuel properties on the performance and emissions of a low temperature combustion diesel engine. Two conventional fuels, diesel and gasoline, were blended to formulate the wide-distillation fuels with various cetane numbers and volatilities. The results show that cetane number is the major factor that affects low temperature combustion characteristic, while volatility only plays a minor role. Due to lower cetane number, fuel with high gasoline blending ratio prolongs ignition delay, and thus effectively reducing soot emissions. Volatility can be greatly improved with high gasoline blending ratio, which is beneficial to soot reduction. In addition, the indicated thermal efficiency can also be improved by applying fuels with higher gasoline content, which can be attributed to the increased burning rate resulting from improved mixing processes. The formulated wide-distillation fuels only have a minor influence on gaseous emissions, such as NOx, THC and CO. It is shown that although ultra-low NOx can be achieved by applying wide-distillation fuels and massive EGR, CO and THC emissions still need to be solved, especially for the fuel with high gasoline blending ratio, which tends to produce more THC emissions.