Research On Modeling Based On High-resolution Measurement Of Oxygenated Volatile Organic Compounds In Light Vehicles In The Pearl River Delta

Volatile organic compounds（VOCs）,as the main precursors of ozone（O₃）,have been studied to prevent and control the key to reducing O₃.In the Pearl River Delta,the exhaust emissions of light-duty vehicles as the main vehicle models are the main source of VOCs.The analysis of light-duty vehicle VOCs emissions remains in consideration of the limitations of sparse sample size and single working conditions.The research bottleneck is the inability to finely identify the dynamic characteristics of VOCs emissions.Therefore,the construction of the current emission model has not been supported by more comprehensive actual measurement research.In this study,an online and offline VOCs measurement system was built in response to the key issues of the current research,and bench test experiments were carried out at vehicle inspection stations in the Pearl River Delta.The light-duty gasoline vehicles in use in Guangzhou cover the National I-National V emission standards.,Its high-resolution emission characteristics of exhaust VOCs carry out online measurement,and use online instruments to finely identify emission changes from a dynamic perspective to compensate for the limitations of offline measurement,obtain key influencing factors and try to build an emission model.Online and offline tests reveal the VOCs emission characteristics of light-duty vehicles from different angles.In offline measurement,the composition spectrum of VOCs under VMAS working condition and TSIC working condition has varying degrees of magnitude difference,and the emission factor obtained under VMAS working condition is slightly higher than the result of TSIC working condition under different national standards.Based on the comparison of other studies,vehicle emissions are significantly reduced under hot operating conditions.The dynamic identification of online measurement found that the national I was updated to the national V,and the total VOCs emission dropped at the level of 99%.With the tightening of the national standard,the correlation between various components generally dropped from above 0.90 to 0.31-0.74,and alcohols and other components showed a negative correlation or no correlation.The distribution of VOCs emissions is concentrated in the variable speed phase,which is higher than the proportion of the idling and constant speed phases.Among them,OVOCs such as formaldehyde,acetaldehyde and acetone maintain high and stable emissions during different speed changes.The attempt to build a light vehicle emission model is based on obtaining OVOCs emission factors for light vehicles including formaldehyde,acetaldehyde,acetone,MVK（butenone）,MEK（methyl ethyl ketone）,benzaldehyde,methanol,and ethanol.National I-The national V emission standards are 12.48 mg/km,10.20 mg/km,5.41 mg/km,4.21 mg/km and 1.61 mg/km respectively,and the overall emission reduction is only 87.2%.The study found that OVOCs emissions are closely related to the modified carbon combustion coefficient（MCE）and specific power（VSP）.According to different national standard vehicles,VSP and emission rate（ER）,MCE and mileage-based emission factors（EFs）are fitted respectively,Obtained the first-order linear functional relationship ER=a₁*VSP+b₁,EFs=a₂*MCE+b₂ with R² at the level of 0.46-0.96,and simplified the functional relationship between the MCE and the EFs of OVOCs from the results to The modified carbon loss rate（MCL）obtains a more simplified proportional function relationship between MCL and OVOCs EFs EFs=b₂*MCL.In view of these close relationships,the model developed can predict the emission factors of light-duty gasoline vehicles under hot operating conditions,and make a significant contribution to the compilation of OVOCs and even VOCs emission inventories.In view of this,this research has identified light-duty vehicle emission characteristics from offline and online perspectives,constructed a model for predicting the emission of light-duty vehicles in actual driving conditions,and explored the ideas and directions of vehicle emission model construction using the OVOCs model.