非道路柴油机气态污染物测量的不确定度研究

Research on the Uncertainty of Measurement of Gaseous Pollutants in Non-road Diesel Engines

本文旨在研究非道路柴油机气态污染物排放测量的不确定度,非道路柴油机在发动机台架上运行了5次非道路稳态循环试验(NRSC),采用全流稀释采样系统和排放分析仪,对NO_(x)和HC排放进行测量,并对测量结果进行不确定度分析。将NO_(x)比排放的不确定度通过3个分量(NO_(x)质量流量、发动机功率、NO_(x)湿度校正系数)进行A类、B类不确定度评定。将HC比排放的不确定度通过2个分量(HC质量流量、发动机功率)进行A类、B类不确定度评定。研究结果表明:NO_(x)的比排放扩展不确定度为0.2471g/(kW·h),置信概率为95%;HC的比排放扩展不确定度为0.0017g/(kW·h),置信概率为95%。二者不确定度的最大贡献者是背景校正浓度重复性测量引入的A类不确定度,即发动机和后处理状态的稳定性对排放结果的不确定度影响较大。

This article aims to investigate the uncertainty of measurement of gaseous pollutants emissions from non-road diesel engines.Non-road diesel engines were tested on an engine bench for 5 NRSC test cycles using a full flow dilution sampling system and an emission analyzer to measure NO_(x)and HC emissions,and the uncertainty of the measurement results was analyzed.Evaluate the uncertainty of NO_(x)specific emissions through three components(NO_(x)mass flow rate,engine power,NO_(x)humidity correction factor)for Class A and Class B uncertainty.Evaluate the uncertainty of HC specific emissions through two components(HC mass flow rate,engine power)for Class A and Class B uncertainty.The research results indicate that the expand uncertainty of NO_(x)specific emissions is 0.2471g/(kW·h),with a confidence probability of 95%;The expand uncertainty of HC specific emissions is 0.0017g/(kW·h),with a confidence probability of 95%.The biggest contributor to the uncertainty of both is the Class A uncertainty introduced by the background corrected concentration repeatability measurement,which means that the stability of the engine and aftertreatment state has a significant impact on the uncertainty of emission results.