A study on the performance enhancement of heat pump using electric heater under the frosting condition: Heat pump under frosting condition

The purpose of the present study is to enhance the heating capacity and increase COP under the frosting condition during heating operation of small capacity air-to-air heat pump. We applied an electric heater in front of outdoor unit of heat pump instead of indoor unit as usual. When the outdoor temperature is 2 °C/1 °C (DB/WB), the present heat pump turns on the electric heater in outdoor unit. The heating capacity increases 38.0% and COP increases 57.0% in comparison with those of conventional heat pump. When the outdoor temperature is 4 °C/2 °C (DB/WB), the electric heater is in ON/OFF mode according to the temperature of the evaporator. The heating capacity increases 9.1% and COP increases 71.1% in comparison with those of conventional heat pump.