柴油机TR燃烧系统实现低温预混合燃烧的研究

为了验证TR燃烧系统降低发动机排放、实现低温预混合燃烧的能力,在一台经过改造的单缸135柴油机上进行了降低压缩比、燃用柴油-乙醇混合燃料和推迟供油的试验研究.结果表明,压缩比ε降低后,着火推迟,最大放热率增加,缸内最高压力和最高温度降低,NOx排放也降低.但是中高负荷时燃烧速率降低,有效油耗率增加.当燃用乙醇体积含量20%的乙醇-柴油混合燃料时,与燃用柴油燃料相比,着火延迟期延长,烟度大幅度降低.小负荷时缸内最高压力、最高温度、最大放热率和燃烧速率都降低,NOx降低较多;中高负荷时最大放热率高于后者,燃烧速率提高,NOx降低得较少.当供油定时从15°CA BT-DC推迟到13°CA BTDC后,烟度基本不变.

Realization of Low-Temperature Premixed Combustion with Diesel TR Combustion System

To clarify the ability of TR (Three-rapidity) combustion system for reducing emissions and realizing low-temperature premixed combustion, a series of tests were carried out in a modified 135 single-cylinder diesel engine, including lowering compression ratio, using diesel-ethanol blend and delaying injection timing. The results show that the decreas of compression ratio results in ignition delay, the increase in maximum rate of heat release and maximum cylinder pressure, the decrease in maximum mean gas temperature and NOx. However, at the medium and high loads the combustion rate would decrease and the brake specific fuel consumption would increase. Compared to diesel combustion, ethanol-diesel combustion prolongs ignition delay period and remarkably lowers the exaust smoke. The maximum cylinder pressure, maximum gas temperature, maximum heat release rate and combustion rate will be decreased somewhat under low load, while under medium and high loads, a higher heat release rate and quicker combustion rate present with little decreas of NOx. In addition, delaying of fuel delivery advance angle from 15° CA BTDC to 13° CA BTDC leads to little variation in smoke at all.