DEFROST SYSTEM FOR REFRIGERATION DEVICE AND COOLING UNIT

摘要

A defrost system includes: a cooling device which is disposed in a freezer, and includes a heat exchanger pipe with a difference in elevation disposed in a casing, and a drain receiver unit disposed below the heat exchanger pipe; a refrigerating device configured to cool and liquefy CO 2 refrigerant; a refrigerant circuit for permitting the CO 2 refrigerant cooled and liquefied in the refrigerating device to circulate to the heat exchanger pipe; a bypass pipe connected between an inlet path and an outlet path of the heat exchanger pipe to form a CO 2 circulation path including the heat exchanger pipe; an on-off valve disposed in each of the inlet path and the outlet path of the heat exchanger pipe and configured to be closed at a time of defrosting so that the CO 2 circulation path becomes a closed circuit; a pressure adjusting unit for adjusting pressure of the CO 2 refrigerant circulating in the closed circuit at the time of defrosting; and a brine circuit which includes a first lead path disposed adjacent to lower area of the heat exchanger pipe in the cooling device and forming a first heat exchanger part for heating the CO 2 refrigerant circulating in the heat exchanger pipe, with brine, in the lower area of the heat exchanger pipe, in which the defrost system permits the CO 2 refrigerant to naturally circulate in the closed circuit at the time of defrosting by a thermosiphon effect.