Emissions Characteristics Of Non-road Mobile Machinery And Experiment Study On Exhaust Gas Aftertreatment Devices In Shunde District

In recent years,with the improvement of air pollution emission standards and the implementation of air pollution control measures,the emission reduction potential of major sources such as power plants,industrial sources,and motor vehicles has been decreasing,and the problem of non-road mobile machinery emissions has become prominent.Accurately quantified the emission of non-road mobile machinery as well as the impact of non-road mobile machinery emissions on air quality are the basis of the formulation of non-road mobile machinery emission control strategies.In this study,the power-based emission factor method was used to develop the 2016 Shunde non-road mobile machinery emission inventory,and the uncertainty of the emission inventory was quantified based on Monte Carlo Method.And then,the WRF-CMAQ air quality model system was used to investigating the impact of non-road mobile machinery emissions on air quality.In addition,the exhaust gas aftertreatment devices were installed on the filtered non-road mobile machinery（one forklift,one excavator,and one loader）and the tracking test was carried out simutaneously.The influence of the aftertreatment devices on the operating conditions of vehicles and the reduction efficiency of exhaust gas emissions were evaluated according to the tracking test results.The results show that the emissions of NO_x,PM₁₀,PM_2.5,VOCs,and CO from non-road mobile machinery in Shunde district in 2016 were 4350t,411t,390t,560t,and 2901t,respectively.The emissions of NO_x and PM_2.5.5 accounted for 16.1%and 10.3%of the total anthropogenic emissions,respectively,it indicated that the non-road mobile machinery had become one of the main source of NO_x and PM_2.5 in Shunde district.What’s more,the uncertainty of NO_x,PM₁₀,PM_2.5,VOCs,and CO in the emission inventory were-26.4%³2.6%,-34.3%⁴6.4%,-33.9%⁴5.9%,-34.2%⁴7.3%,and-49.4%⁸2.9%,respectively.The model simulation results show that the non-road mobile machinery emissions in Shunde district in2016 had a positive contribution to the generation of NO₂,and the contribution showed seasonal differences.Among them,the contribution in October（1.9 ug/m³）was the largest while the contribution in April（1.0 ug/m³）was the smallest.The non-road mobile machinery emissions increased the PM_2.5.5 concentration by 0.2 ug/m³,0.2 ug/m³,0.3 ug/m³,and 0.3 ug/m³ in January,April,July,and October,respectively.As for O₃,the non-road mobile machinery emissions increased the O₃ concentration by 1.4 ug/m³ in July,while reduced the concentration of O₃ by1.6 ug/m³,2.1 ug/m³ and 1.2 ug/m³ in January,April,and October,respectively.The possible reason is the poor light exposure in January,April,and October was adverse to the photochemical reactions,which promoted the titration effect of NO to O₃.Finally,the tracking test results show that the tested vehicles were maintained a stable working state after the installation of the aftertreatment devices,and the exhaust temperatures were mainly concentrated in the optimal temperature range for the oxidation reaction of the particulate matter in the after-treatment device,and the exhaust back pressure had little effect on the performance of the engine,which can ensure the normal operation of the engine’s functions.In addition,after 6 months of installation of the aftertreatment device,the reduction efficiency of the exhaust smoke value of forklift,excavator and loader was 88%,89%and 83%,respectively,indicating that the device has a significant effect on the reduction of the vehicle exhaust smoke values.