US Patent 7975502 Heat pump apparatus and operating method thereof

In a heat pump apparatus of the invention, a refrigerant is circulated through a compressor 31, a radiator 32, a first throttle apparatus 33, a heat exchanger 34, a second throttle apparatus 35 and an evaporator 36 in this order. The heat exchanger 34 can be utilized as both a radiator and an evaporator by operating the first throttle apparatus 33 and the second throttle apparatus 35. Therefore, even if the outside air temperature is high, discharge pressure and suction pressure of the compressor do not rise, the heat pump apparatus can be operated in a stable refrigeration cycle, and energy can be saved.