| 摘要 |
PURPOSE: A method for defrosting operation of heat pump is provided to prevent inflow of liquefied refrigerant into a compressor when defrosting operation is switched back to heating operation. CONSTITUTION: A defrosting operation comprises the steps of: a step reducing difference of pressure all over a heat pump system by decreasing frequency of a compressor(11) to minimum frequency and fully opening an electronic expansion valve(22); and a step removing frost by switching a reversing valve(12) to cooling mode and then increasing frequency of the compressor to maximum frequency. A defrosting cancellation operation comprises the steps of: a step reducing difference of pressure all over the heat pump system by decreasing frequency of the compressor when a temperature sensor(14b) installed on a tube of an outdoor heat exchanger(14) detects that defrosting cancellation condition is satisfied; a step completely closing the electronic expansion valve and switching the reversing valve to heating mode after completion of defrosting; and a step gradually increasing frequency of the compressor and gradually opening the electronic expansion valve.
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