PURPOSE: To enable utilization of not only cooling capacity in a main refrigerant circuit but also cooling capacity in a cold heat storage circuit and to enable reduction of the running cost of a device by a method wherein a refrigerant in a bypass passage is conveyed to the main refrigerant circuit to perform cooling operation as a cold heat stored in a heat storage tank is collected.

CONSTITUTION: A title device comprises a main refrigerant circuit 6 formed by connecting together a compressor 1, a condenser 2, a vaporizer 4 and a pressure reducing mechanism 3 for the vaporizer 4, a heat storage tank incorporating a heat storage medium capable of storing heat, a heat exchange mechanism 9 to perform heat exchange between the heat storage medium of a heat storage tank 8 and a refrigerant, a bypass passage 11 for interconnecting a liquid line 5a running between the condenser 2 and the pressure reducing mechanism 3 and a gas line 5b through the heat exchange mechanism 9 so that the refrigerant can bypass; and a conveying device 13 connecting the input side to a part of the bypass passage 11 and capable of conveying a refrigerant, condensed by the heat exchange mechanism 9 through heat exchange with a cold heat stored in the heat storage tank 8, to a liquid line 5a of the main refrigerant circuit 6.