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The Dual Hot-Gas Bypass Defrosting (DHBD) cycle is an effective defrosting method compared to a Reverse Cycle Defrosting (RCD) method to remove frost from the outdoor heat exchanger (HEX) of an air-to-air heat pump, especially the outdoor temperature is above 0 °C. However, the DHBD method has a drawback when the heat pump operates in cold outdoor environment, below 0 °C due to rapid decrease in refrigerant temperature followed by lower hot-gas bypass temperature. In order to overcome lower discharge temperature of compressor, a combined defrosting cycle with DHBD and the accumulator heating method is developed. An induction heater (IH) is adopted as the accumulator heater. The dynamic performance and defrosting time are compared between the conventional RCD method and the combined DHBD–IH method using a medium size air-to-air heat pump of 16 kW under the condition of −5 …