Sublimation defrost system and sublimation defrost method for refrigeration apparatus

A sublimation defrost system for a refrigeration apparatus including:

• a cooling device which is disposed in a freezer, and includes a casing and a heat exchanger pipe disposed in the casing;
• a refrigerating device for cooling and liquefying a CO2 refrigerant;
• and a refrigerant circuit which is connected to the heat exchanger pipe and which is configured to permits the CO2 refrigerant cooled and liquefied in the refrigerating device to circulate to the heat exchanger pipe, the defrost system comprising:
• a dehumidifier device for dehumidifying freezer inner air in the freezer;
• a CO2 circulation path which is formed of a circulation path forming path connected to an inlet path and an outlet path of the heat exchanger pipe, and includes 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 CO2 circulation path becomes a closed circuit;
• a circulating unit for CO2 refrigerant, the circulating unit being disposed in the CO2 circulation path;
• a first heat exchanger part configured to cause heat exchange between a brine as a first heating medium and the CO2 refrigerant circulating in the CO2 circulation path;
• and
• a pressure adjusting unit which adjusts a pressure of the CO2 refrigerant circulating in the closed circuit at the time of defrosting so that a condensing temperature of the CO2 refrigerant becomes equal to or lower than a freezing point of a water vapor in the freezer inner air in the freezer;
• wherein
• the defrosting is able to be achieved without a drain receiving unit.