Performance characteristics of a dual-evaporator heat pump system for effective dehumidifying and heating of a cabin in electric vehicles

In electric vehicles, air-conditioning (AC) units and electric heaters have been used for dehumidifying and heating the cabin. However, the air heating process in the electric heater causes higher power consumption due to a lower air temperature entering the electric heater from the sensible cooling in the humidifying process. In this study, a heat pump (HP) and a dual-evaporator heat pump (DHP) combined with a heater are proposed as effective dehumidifying and heating units using waste heat recovery from the dehumidifying process. The performances of the AC, HP, and DHP systems were measured and compared by varying the indoor air wet bulb temperature and compressor speed ratio. Generally, the HP and DHP systems showed superior performance to the conventional AC system in the dehumidifying and heating operation. At the indoor air wet bulb temperature of 13°C, the DHP system showed 53% and 62% higher specific moisture extraction rate and COP, respectively, than the HP system.