国六柴油机颗粒物数量排放测量结果的不确定度评定

Uncertainty Evaluation of Particle Number Emissions Measurement Results from ChinaⅥDiesel Engine

根据试验程序和测量方法建立了国六柴油机颗粒物数量排放的数学计算模型,通过理论方法对模型中测量重复性、颗粒计数器精度、部分流稀释系统精度和测功机系统精度等各种参数的相对标准不确定度进行了分析,得到了颗粒物数量排放的不确定度评定结果。通过采取温度和压力控制参数优化、更换滤芯和计数单元重新标定等改进措施,颗粒物数量比排放量的合成相对标准不确定度为4.82%,满足国六标准对颗粒物数量测量的精度要求。

This test focuses on particle number(PN)emissions from ChinaⅥEngine.According to the test procedure and measurement method,the mathematics model of PN emissions was established.Relative standard uncertainty of measurement repeatability,particle counter precision,fractional flow dilution system precision,dynamometer system precision and so on various parameters were analyzed by means of theoretical model.Finally evaluation results of uncertainty of PN emissions were obtained.The improvement measures such as optimization of temperature and pressure control parameters,change of filter element and recalibration of counting unit are adopted.The synthesis of relative standard uncertainty of PN emissions was 4.82%,satisfying the requirement of the standards and regulations for PN measurement precision.