汽油/柴油双燃料不同燃烧模式能量平衡分析研究

Energy Balance Analysis of Different Dual Fuel Combustion Modes Fuelled with Gasoline and Diesel

基于热力学第一定律,利用试验研究和工作过程模拟方法对汽油/柴油双燃料高比例预混合燃烧(highly premixed charge combustion mode,HPCC)和混合燃料低温燃烧(low temperature combustion,LTC)模式进行了能量平衡分析研究。HPCC燃烧模式中包括柴油早喷E-HPCC和柴油晚喷L-HPCC两种方式。研究结果表明:在相同的主放热时刻(CA50)条件下,LTC燃烧模式放热率峰值最高,燃烧持续期最短,导致缸内温度最高,传热损失最大;L-HPCC燃烧模式燃烧持续期最长,废气带走的热损失最多;由于采用汽油进气道喷射,两种汽油/柴油双燃料HPCC模式的不完全燃烧损失均远高于LTC模式,但总体上三种燃烧模式的指示热效率基本相当。随着EGR率的增加,LTC模式的传热损失上升,废热损失下降,L-HPCC模式则恰好相反,而对E-HPCC模式影响较小。随着汽油比例的升高,三种燃烧模式均表现为传热损失增大,废热损失下降,燃烧损失下降,但对指示热效率影响较小。

Experiment and simulation were conducted to carry out energy balance analysis on highly premixed charge combustion mode （HPCC）and low temperature combustion （LTC）mode of dual-fuel of gasoline and diesel based on first law of thermodynamics. In the HPCC mode, both early-injection （E- HPCC） and late-injection （L-HPCC）of diesel were used. The results demonstrate that, with a fixed combustion phasing indicated by CA50, LTC mode has the highest heat release rate and shortest corhbustion duration, resulting in the highest combustion temperature and biggest heat transfer loss while the L-HPCC mode has the longest combustion duration and highest exhaust heat loss. Due to gasoline being injected in intake port, incomplete combustion losses of the E-HPCC mode and L-HPCC mode are much higher than that of LTC, but the thermal efficiencies of the three combustion modes are similar in general. With the increase of EGR rate, the heat transfer loss of LTC mode increases and exhaust heat loss decreases, L-HPCC shows just the opposite trend, whereas EGR has a little impact on E-HPCC. With the increase of gasoline rate in cylinder, all three combustion modes show higher heat transfer loss, lower exhaust heat loss and combustion loss, but no obvious change in indicated thermal efficiency.