弱含氧燃料组分在柴油机上的燃烧过程与排放特性

Combustion Process and Emisssion Chracteristics of a Diesel Engine Fueled with Low-Oxygen Fuel Components

通过在体积分数为90%的柴油中分别掺混10%生物柴油、10%DMC,连同柴油组成B10、D10和柴油3种燃料,考察了低比例含氧燃料对柴油机燃烧过程、经济性和排放性的影响.试验结果表明:标定工况下,2种含氧燃料对柴油机缸内最大爆发压力和压升率峰值影响不大,而DMC的加入使D10的放热峰值明显升高;和柴油相比,B10的滞燃期缩短约1℃A,而D10的滞燃期较原机状态延长约2℃A,可见DMC造成的着火延迟效应要比同比例生物柴油造成的着火提前效应更为明显;B10的燃油消耗率与柴油基本相当,而D10的燃油消耗率明显上升;发动机燃用B10时,除NOx在全负荷时升高7.9%外,CO、HC和烟度排放相对有所降低,而混合燃料中DMC的引入虽不利于HC和CO的氧化,但可消除柴油机燃用石化柴油时NOx和烟度排放此消彼长的关系,D10的NOx和烟度排放平均要比柴油分别降低约13.1%和17.7%.综合来看,在柴油中添加低比例生物柴油或DMC可在几乎不影响柴油机性能的基础上部分实现对柴油的完美替代.

The addition of 10% biodiesel and 10%DMC, together with pure diesel form three test fuels which were called B10, D10 and diesel respectively, then effects of different oxygenated fuels with low proportional addition on combustion process, economic and emission characteristics were investigated in a single-cylinder engine. Results showed that under the rated operating condition, these two oxygenated fuels had little influnce on engine＇s maximum cylinder pressure and pressure rise rate peak, the maximum heat release rate of B10 was slightly decreased, while the addition of DMC, that of D10 was increased significantly. As compared to diesel, the ignition delay of B10 has shortened by about 1℃A which the ignition delay of D10 has extended by 2 ℃A;the effect of DMC on prolonging ignition delay was more obvious than the impact of biodiesel with same proportion on shortening ignition delay. The fuel comsupation of B10 was almost the same as that of diesel, while that of D10 was higher. The B10 could slightly reduce HC,CO and smoke emissions, except for a 7.9% higher NOx emissions at full load. Though the introduction of DMC in mixed fuels didn＇t promote the oxidation of HC and CO, it could simultaneously reduce NOx and smoke emissions. The NOx and smoke emissions of D10 have decrased by 13.1% and 17.7%. On the whole, the low proportional addition of biodiesel and DMC in diesel could partly achieve excellent subtitute of diesel without influencing the engine＇ s performance.