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为了解空气湿度对柴油机排放的影响,该文利用KIVA-3V软件,建立柴油机燃烧过程模型,研究了空气含湿量分别为0、5、10和20g/kg时柴油机NOx和碳烟排放的变化规律,模拟了热物性参数、进气成分、燃烧中间产物演化过程。计算结果表明:随着空气湿度增加,NOx排放近似呈线性减少,含湿量20g/kg时NOx排放可减少30%以上,除大负荷外,湿度对碳烟排放影响均较小。随着湿度增加,除了N2和O2减少,自由基O和OH也会减少。在大负荷、高湿度时,O2浓度的下降并由此引起的碳烟氧化量减少是碳烟生成量增加的重要原因,空气湿度对碳烟排放具有双重影响。
In order to understand the influence of air humidity on diesel engine emissions, a model of diesel engine combustion process was established by using KIVA-3V software to study the changes of diesel engine NOx and soot emissions at air humidities of 0, 5, 10 and 20 g / kg respectively The law, the simulation of the thermophysical parameters, the composition of the intake air, the evolution of combustion intermediates. The results show that the NOx emission decreases linearly with the increase of air humidity, and the NOx emission can be reduced by more than 30% when the moisture content is 20g / kg. The humidity has little influence on the soot emissions except the heavy load. As humidity increases, in addition to the reduction of N2 and O2, the free radicals O and OH decrease. Under heavy load and high humidity, the decrease of O2 concentration and the reduction of soot oxidation are the important reasons for the increase of soot generation. Air humidity has a dual impact on soot emissions.