This invention discloses a pump-driven, high-efficiency, low-pressure
defrosting air source
heat pump system and its control method. The
system includes a compressor, a first
heat exchanger, a second
heat exchanger, a third
heat exchanger, a throttling element, an
energy storage module, a gas-liquid separator, a defrost bypass
branch, and a pump return
branch. The control method includes: executing a heating and heat storage mode to store heat in the
energy storage module; responding to
defrosting conditions, executing a heating and
defrosting mode to extract heat from the
energy storage module; while continuously supplying heat to the first heat exchanger, using low-pressure
refrigerant to melt the
frost layer on the wall of the third heat exchanger; opening the defrost bypass
branch to allow some
refrigerant to bypass from the inlet to the outlet of the third heat exchanger to reduce the
internal pressure drop; and simultaneously starting the
refrigerant pump to pump the liquid refrigerant at the bottom of the gas-liquid separator to the inlet of the second heat exchanger to enhance heat absorption. This invention eliminates the need for
system shutdown during defrosting, achieving efficient defrosting and stable heating through the energy storage module, the defrost bypass branch, and the pump return branch, significantly improving system energy efficiency and comfort.