Impact of Ambient Temperatures on VOC Emissions and OFP during Cold Start for SI Car Real World Urban Driving 2009-01-1865
New EU environmental law requires 31 ozone precursor VOCs (Volatile Organic Compounds) to be measured for urban air quality control. In this study, 23 out of the 31 ozone precursor VOCs were measured at a rate of 0.5 HZ by an in-vehicle FTIR (Fourier Transform InfraRed) emission measurement system along with 15 other VOCs. The vehicle used was a EURO2 emission compliant SI car. The test vehicle was driven under real world urban driving conditions on the same route by the same driver on different days at different ambient temperatures. All the journeys were started from cold. The VOC emissions and OFP (Ozone Formation Potential) as a function of engine warm up and ambient temperatures during cold start were investigated. The exhaust temperatures were measured along with the exhaust emissions. The temperature and duration of light off of the catalyst for VOCs was monitored. The results demonstrated that there was a significant increase in VOC emissions and OFP as the ambient temperature decreased. The initial cold start duration for VOCs and OFP was about 200 seconds. The OFP was approximately five times as high as the VOC emissions.