车用压缩天然气组分对天然气发动机燃烧、排放影响的计算分析

The Calculation and Analysis on the Influence of CNG Constituent for Vehicle on The Combustion and Exhaust Emission of Engine

根据我国天然气组分变化的情况,采用双区模型模拟计算的方法,研究了在过量空的系数为1时,天然气组分变化对火花点火式发动机燃烧压力、燃烧温度及CO_2、CO、NO排放特性的影响。计算结果表明:干天然气、具有我国平均组分的天然气和凝析气,其组分的变化对动力性影响不大,主要影响排放特性;但如果天然气中含有过多的低热值燃料或惰性气体(但仍符合我国的天然气成分标准),则同时对动力性和排放特性产生明显的影响。将计算结果与我国的汽车用压缩天然气标准中的技术要求进行了对比,指出了我国车用天然气技术标准的不足。

The influence of the variation of natural gas constituent on combustion pressure,combustion temperature and the exhaust characteristic of NO,CO,CO2 were studied by useing double range model when excess air coefficient was 1. It shows that the influence of consituent variations for the dry natural gas,the natural gas with average constituent and condensation gas on power performance is not much,but exhaust emission characteristic is markedly influenced. If there is too much inert gases or the fuel whose heat value too lower (but it still accords with natural gas standard for vehicle) , the power performance and exhaust emission characteristic were markedly influenced synchronously. The calculation results were compared with the technique requirement from CNG standard for vehicle in our country. The shortness in the standard was pointed out.