针对国六标准汽车尾气排放检测的溯源性探讨

Traceability Discussion on China VI Standard Automobile Exhaust Emission Detection

随着我国汽车保有量不断增加,汽车尾气造成的污染问题日益严峻,为了控制环境污染问题,我国早在1987年颁布了《中华人民共和国大气污染防治法》。2013年欧盟发布了欧六标准(EURO VIA-VID),我国借鉴欧六标准结合本国国情,于2016年颁布GB 18352.6-2016《轻型汽车污染物排放限值及测量方法(中国第六阶段)》(以下简称国六标准),并于2020年1月始分阶段实施,该标准对汽车尾气排放的监管和质量控制溯源提出了新的要求。对比国五标准和国六标准排放物质量控制要求的区别,介绍了国六排放标准中更新排放限制的污染物:一氧化碳(CO)、氮氧化物(NOx)、非甲烷碳氢化合物(NMHC)、氧化亚氮(N2O)、粒子数量(PN)、颗粒物(PM)等的测量方法。同时从汽车尾气排放国家气体标准物质研制、计量标准的建立以及全国汽车检测中心的成立等方面介绍了我国尾气排放检测和溯源技术。分析了现有能力和技术水平无法满足国六标准中部分排放检测要求,提出了目前溯源技术中需要进一步优化研究的项目,如粒子数量(PN)测量仪中凝结核粒子计数器,指出下一步对颗粒浓度衰减系数、挥发性颗粒物去除效率、稀释比等计量指标需要加快研究和完善。针对欧六标准规定的一氯二甲酸酯、苯并[a]芘污染物测定要求,我国目前还没有相应标准物质和溯源体系,需研发符合要求的标准物质并建立溯源标准,做好技术储备,以应对国际国内日益更新的质控要求,并对欧洲第七阶段排放标准(欧7)提案的发布提出应对建议。

As the number of vehicles in China continues to increase,pollution from automobile exhaust has become increasingly severe.To control environmental pollution,China promulgated the"Air Pollution Prevention and Control Law of the People's Republic of China"as early as 1987.In 2013,the European Union released the Euro VI standard(EURO VI A-VI D).China,drawing on the Euro VI standard and considering its national conditions,issued GB 18352.6-2016"Limits and Measurement Methods for Emissions from Light-Duty Vehicles(China 6)"(hereinafter referred to as the China VI standard)in 2016,which was implemented in phases starting from January 2020.This standard has set new requirements for the regulation and quality control traceability of automobile exhaust emissions.This article compares the differences in emission quality control requirements between the China V and China VI standards,and introduces the measurement methods for updated emission-limited pollutants in the China VI standard,including carbon monoxide(CO),nitrogen oxides(NOx),non-methane hydrocarbons(NMHC),nitrous oxide(N2O),particle number(PN),and particulate matter(PM).It also describes China's exhaust emission detection and traceability technology from the aspects of developing national gas reference materials,establishing measurement standards,and founding national automobile testing centers.The analysis shows that existing capabilities and technical levels cannot meet some emission detection requirements in the China VI standard.The article proposes areas in current traceability technology that need further optimization,such as the condensation particle counter in particle number(PN)measurement instruments.It points out that research and improvement should be accelerated on metrological indicators like particle concentration attenuation coefficient,volatile particle removal efficiency,and dilution ratio.Regarding the requirements for determining methyl chloroformate and benzo[a]pyrene pollutants specified in the Euro VI standard,China currently lacks corresponding reference materials and traceability systems.It is necessary to develop compliant reference materials and establish traceability standards to prepare for increasingly updated quality control requirements both domestically and internationally.The article also offers suggestions in response to the proposed European seventh stage emission standard(Euro 7).