| With the rising of motor vehicle ownership in China, the engine exhaust pollutants have brought more and more hazard to the atmospheric environment. The emissions of diesel vehicle’s NOx and particulate accounted for more than 70% of total emissions of motor vehicles in 2012, the major contributor was heavy-duty diesel vehicles. Only more stringent emission regulations be implemented can effectively control the harmful of automobile exhaust pollutants to the humans’ survival environment. The research of diesel engine emission control is largely dependent on the accurate emission test system, currently, the shunt dilution sampling system and the full flow dilution sampling system are the major emission pollution test system of diesel engine in China. According to the GB17691-2005 emission regulations promulgated by State Environmental Protection Administration in January 1,2005, this paper employed two sets of emission test system to test a heavy-duty diesel engine, in order to discover the correlation of two emission test system through the analysis result.The domestic study on engine emission test technology is relatively less, based on a lot of references of foreign scholars research, this paper clearly analyzes the harm and formation mechanism of engine exhaust pollutants, and combined with current domestic emissions regulations to formulate corresponding experimental scheme. Firstly, I studied the engine operating parameters, the influence of gaseous pollutants and particulate to sampling results which was caused by intake temperature in the cold, exhaust back pressure, intake temperature and pressure. The consistency between the engine and the test equipment have been verified, the test used a single variable method, namely changed only one parameters and remained other operating parameters unchanged at the rated point to test ESC steady cycle. The test results show that the four kinds of working parameters have relatively large influence on the sampling results of NOx, HC, CO and PM.The parameter setting of sampling system is another important factor to affect the results of sampling, this paper carried comparison test by a single variable method, used ESC steady test cycle stipulated in the emissions regulations to respectively research the sampling parameters of shunt sampling system and full flow sampling system impact on particulate sampling results. Mainly analyzed the effect of sampling results of particles by some parameters, including the dilution sampling system shunt, filter paper temperature, residence time in dilution tunnel, loading of filter paper and sampling time. At the same time, analyzed the influence of sampling results caused by total flow of exhaust after the full flow dilution sampling system and secondary dilution ratio.According to the above test data, take emissions of particulate as the dependent variable to apply least squares algorithm to modeling analysis in the data analysis software SPSS. The model establishment of full flow model sampling system and partial flow sampling system are more successful, by comparing the results of both analytical model can infer that partial flow sampling system can replace full flow sampling system. |
