GB801797A - Reverse cycle defrosting system for refrigerators - Google Patents

Abstract

801,797. Refrigerating. PRESSED STEEL CO., Ltd. Aug. 15, 1956, No. 24926/56. Class 29 The invention relates to a compression refrigeration system including a liquid receiver between the evaporator and condenser in which the evaporator is defrosted by reversing the flow of refrigerant, and provides that refrigerant flows through the condenser 302 in the same direction during both normal operation and defrosting, the liquid receiver acting as a disengagement vessel during defrosting. This is effected by adding a line 315 between the evaporator 305 and condenser 302 and a line 314 between the liquid receiver 303 and the compressor 301, both used only during defrosting. In the preferred form the refrigerant circuit includes a reversing slide valve 340 and the pipe 315 is placed in heat exchange with the evaporator drip tray 351 and drain 352, being connected to the condenser inlet through a non-return valve 316, preferably a high-side float valve, and an expansion valve or device 319. Normal refrigerant flow is from the compressor 301 through lines 306, 309 to the condenser 302 and a liquid receiver vessel 303 from where liquid refrigerant passes to the evaporator 305 through the thermostatically controlled expansion valve 304, the evaporated refrigerant flowing to the compresser through suction lines 310, 311. On defrosting the slide valve 340 is operated and the refrigerant flows through evaporator 305, line 315, non- return valve 316 and expansion device 319 to the condenser 302, now acting as an evaporator, from where it passes to the receiver 303, vapour flowing through line 314 to the compresser. The non-return valve may be functionally integral with the reversing valve.