Real-world Cold Start Emissions Evaluation for Direct-injection Gasoline Vehicle with PEMS and SEMS

The Real Driving Emissions (RDE) test method has been introduced after 2017 to regulate the vehicle emissions in real-world driving situations by means of on-board emissions measurements. This paper aims to estimate the detailed on-board gaseous emissions from a light-duty direct-injection gasoline vehicle simultaneously using both portable emissions measurement system (PEMS) and sensor-based emissions measurement system (SEMS). Test route is typical urban route and tests environment factors followed the RDE regulation. Carbon dioxide (CO₂), carbon monoxide (CO), nitrogen oxides (NOx), and ammonia (NH₃) emissions were analyzed according to cold start once and followed by hot start conditions. The mass emissions of gas components were calculated based on the exhaust flowrate obtained from OBD parameters, NH₃ emission was calculated based on NO sensor’s data. Two drivers participated in the tests and their emissions difference has been compared. The results indicating cold start caused much more emission than hot start in CO, NOx and NH₃; and aggressive driving behavior would cause more emissions. Simultaneous tests gave chances to better combine the advantages of both measurement systems, and figure out the cause of NH₃ emission, two different patterns of NH₃ emission which depending on cold/hot start method have been found, and the results showed CO emission and catalytic temperature can both be crucial factors to form NH₃ in exhaust gas.