Heat pump system

摘要

A heat pump system includes a refrigerant circuit and a controller. In a heating operation, the usage-side expansion valve is controlled so that a degree of subcooling of outlet refrigerant of the usage-side heat exchanger is equal to a predetermined target degree of subcooling. In a refrigerant recovery control, the heat-source-side expansion valve is controlled so that a degree of superheat of outlet refrigerant of the heat-source-side heat exchanger is equal to a predetermined target degree of superheat, the predetermined target degree of superheat is changed so that the outlet refrigerant of the heat-source-side heat exchanger is wet when the usage-side expansion valve is opened greater than a predetermined opening degree at a start of refrigerant recovery, and change in the predetermined target degree of superheat is cancelled when the usage-side expansion valve is closed smaller than a predetermined opening degree at an end of refrigerant recovery.

主权项

1. A heat pump system comprising:
a refrigerant circuit including
a usage unit having a usage-side expansion valve and a usage-side heat exchangera heat source unit connected to said usage unit, said heat source unit having
a compressor configured to compress a refrigerant,a heat-source-side heat exchanger,a heat-source-side expansion valve, andan accumulator connected to an intake of said compressor; and a controller configured to control said refrigerant circuit
to perform a heating operation in which said usage-side heat exchanger functions as a refrigerant radiator andto control said usage-side expansion valve so that a degree of subcooling of refrigerant in an outlet of said usage-side heat exchanger during said heating operation is equal to a predetermined target degree of subcooling of the refrigerant in the outlet of said usage-side heat exchanger, said controller being further configured to control said refrigerant circuit to perform refrigerant recovery control in which
said heat-source-side expansion valve is controlled such so that a degree of superheat of refrigerant an outlet of said heat-source-side heat exchanger functioning as a refrigerant evaporator is equal to a predetermined target degree of superheat of the refrigerant in the outlet of said heat-source-side heat exchanger,said predetermined target degree of superheat is changed so that the refrigerant in the outlet of said heat-source-side heat exchanger is wet when said usage-side expansion valve is opened to an opening degree greater than a predetermined opening degree at a start of refrigerant recovery, andchange in said predetermined target degree of superheat is cancelled when said usage-side expansion valve is closed to an opening degree smaller than a predetermined opening degree at an end of refrigerant recovery.