Ammonia emissions from range-extended electric vehicles under coupled temperature-HVAC conditions

Ambient temperature and cabin heating or cooling jointly affect engine operation and ammonia (NH₃) emissions from range-extended electric vehicles (EREVs). Two China 6 EREVs were tested in a climatic chamber over an RDE-derived aggressive chassis-dynamometer profile under three coupled temperature-HVAC conditions: 0 °C with heating on, 23 °C with HVAC off, and 40 °C with cooling on. Each condition was repeated three times. Reported trip-level NH₃ emission factors ranged from 15.31 to 17.98 mg/km for SHEV 1 and from 2.65 to 4.69 mg/km for SHEV 2. The coupled conditions affected emission timing and phase distribution more strongly than trip-level factors. Both vehicles had higher urban NH₃ factors at 0 and 40 °C than at 23 °C, coinciding with earlier or prolonged engine operation. Later engine intervention at 23 °C shifted emissions toward rural or motorway operation. SHEV 1 showed large NH₃ peaks during rich motorway operation at 40 °C; SHEV 2 emitted less NH₃ but exhibited isolated pollutant events and high catalyst-temperature signals. These observations support coordinated energy-management and aftertreatment control for the tested vehicles.