不同海拔下氢气/柴油双燃料发动机燃烧与排放特性研究

Research on Combustion and Emission Characteristics of Hydrogen/Diesel Dual Fuel Engines at Different Altitudes

基于大气模拟综合测试系统,模拟0 m、1 000 m和2 000 m海拔的大气压,对不同海拔下氢气/柴油双燃料发动机燃烧与排放特性进行研究。研究结果表明:不同海拔下,随着氢气替代率增加,预混合燃烧增强,缸内燃烧速度加快,缸压峰值升高,其对应相位提前;碳烟和CO排放先下降后上升,NO_(x)排放增加,CO_(2)排放减少。随着海拔上升,过量空气系数减小,有效热效率降低。转速为1 600 r/min时,随着海拔高度升高,预混合燃烧减弱,发动机缸压峰值下降,其对应相位推迟;CO排放最低时,与0 m海拔比较,海拔上升至1 000 m、2 000 m,碳烟排放分别增加44.44%和127.78%,CO排放增加8.95%和16.86%,CO_(2)排放增加4.34%和16.86%,碳烟和CO_(2)排放增幅随海拔增加而上升。转速为3 000 r/min时,随着海拔高度上升,缸压峰值略有升高,缸压峰值对应相位提前,预混合燃烧增强;碳烟、NO_(x)、CO和CO_(2)排放升高,排放增幅随海拔升高而增大。与海拔0 m比较,当碳烟排放最低时,海拔上升至1 000 m、2 000 m,碳烟排放分别升高18.67%和56.04%,NO_(x)排放分别上升14.78%和38.40%,CO_(2)排放分别升高7.29%和15.80%;CO排放最低时,海拔上升至1 000 m、2 000 m,CO排放分别上升24.53%和62.87%。

Based on the comprehensive test system of atmospheric simulation,the combustion and emission characteristics of hydrogen/diesel dual fuel engines at different altitudes were studied by simulating the atmospheric pressures at the altitudes of 0 m,1000 m and 2000 m.The results show that with the increase of hydrogen substitution rates,the premixed combustion is enhanced,the combustion speeds and the peak pressures in the cylinder are increased,and the corresponding phase is advanced at different altitudes.With the increase of hydrogen substitution rates,soot and CO emissions decrease first and then increase,NOx emissions increase,and CO2 emissions decrease.As the altitude increases,the excess air coefficients decreases,and the effective thermal efficiency decreases.When the engine speed is 1600 r/min,the premixed combustion is weakened,the peak pressure of the engine cylinder decreases,and the corresponding phase is delayed with the increase of altitudes.When the CO emissions are the lowest,the soot emissions at the altitudes of 1000 m,2000 m increase by 44.44%and 127.78%respectively,the CO emissions increase by 8.95%and 16.86%respectively,and the CO2 emissions increase by 4.34%and 16.86%respectively,compared with these at the altitude of 0 m.The increase rates of soot and CO2 emissions increase with the increase of altitudes.When the engine speed is 3000 r/min,as the altitudes increase,the peak cylinder pressures increase slightly,the corresponding phase of the peak cylinder pressure is advanced,and the premixed combustion is enhanced.As the altitudes increase,the emissions of soot,NOx,CO and CO2 increase,and the increase rates of emissions increase.When the soot emission is the lowest with the increase of altitudes,soot emissions at the altitudes of 1000 m,2000 m increase by 18.67%and 56.04%respectively,NOx emissions increase by 14.78%and 38.40%respectively,CO2 emissions increase by 7.29%and 15.80%respectively,compared with these at the altitude of 0 m.When the CO emission is the lowest,and the CO emissions at the altitudes of 1000 m,2000 m increase by 24.53%and 62.87%respectively,compared with these at the altitude of 0 m.