Study on Energy Consumption and Emission Characteristics of EHC Coupled DOC+SDPF+SCR-ASC System under WLTC and RDE

With the tightening of emission regulations, electrically heated catalytic converters (EHC) are an important technical solution for diesel vehicles to address the challenges of cold start and RDE emission reduction. This paper investigates the impact of EHC coupled exhaust aftertreatment system (DOC+SDPF+SRR-ASC) on the energy consumption and emission characteristics of light-duty diesel vehicles based on the World Light Vehicle Test Cycle (WLTC) and Real Driving Emissions (RDE). The research results show that under WLTC conditions, compared to EHC off, the time for the SDPF inlet temperature to reach 180 ℃ when EHC on is 44 seconds earlier. The CO emission value of diesel vehicles is 67.5 mg/km, the THC emission value is 49.8 mg/km, the NMHC emission value is 42.5 mg/km, and the NOx emission value is 28.7 mg/km, which is far below the limit requirements of CHINA VI B. Among them, the average urea injection rate increased by 1.1 mg/s, and the overall NOx conversion efficiency increased by 7.1% compared to the EHC off, reaching over 94%. Fuel consumption increased by 2.30%. Under RDE conditions, compared to EHC off, the NOx emissions during the urban operating phase when EHC on have decreased from 129.7 mg/km to 7.9 mg/km, a decrease of 93.9%. The NOx emissions throughout RDE have also decreased from 51.5 mg/km to 6 mg/km, a decrease of 88.3%. This is an important technical solution to meet the requirements of the next phase of the CHINA VII emission regulations.