Refrigeration system

Abstract

A refrigerating system comprises a compressor ( 1 A, 1 B, 1 C), a heat rejection device ( 2 ), an expansion device ( 15 ), an evaporator ( 5 A, 5 B, 5 C) and a receiver ( 4 ), capable of operating with the compressor discharge higher than the critical pressure of the refrigerant; where the flow outlet from the heat rejection device is regulated by a pressure control valve ( 7 ), the pressure downstream of the pressure control valve is regulated by a gas vent valve ( 8 ), the refrigerant flow to the evaporator is further regulated by an automatic control device ( 41, 52, 14 ) at the inlet to the evaporator, and the automatic control device being set to permit intermittent flow of liquid refrigerant to the receiver during normal operation of the system. The refrigerant may be carbon dioxide, which may operate under transcritical pressures e.g. 80 to 120 bar absolute. The receiver acts as a trap for any liquid from the evaporator and ensures that the gas flow to the compressor suction is dry.

1 . A refrigerating system comprising a compressor, a heat rejection device, an expansion device, an evaporator and a receiver, capable of operating with the compressor discharge higher than the critical pressure of the refrigerant; where
 the flow outlet from the heat rejection device is regulated by a pressure control valve,   the pressure downstream of the pressure control valve is regulated by a gas vent valve,   the refrigerant flow to the evaporator is further regulated by an automatic control device at the inlet to the evaporator, and   the automatic control device being set to permit intermittent flow of liquid refrigerant to the receiver during normal operation of the system.   
     
     
         2 . A refrigerating system in accordance with  claim 1  where the refrigerant is carbon dioxide. 
     
     
         3 . A refrigerating system in accordance with  claim 1  where the pressure between the pressure control valve and the expansion device is permitted to rise to approximate the heat rejection device operating pressure by driving the pressure control valve fully open. 
     
     
         4 . A refrigerating system in accordance with  claim 1  where lubricant, which has accumulated in the receiver, can be automatically returned to the compressors through a sampling device. 
     
     
         5 . A refrigerating system in accordance with  claim 1  where pressure rise due to heat gain when the compressors are non-operational is self-limiting by virtue of the size and disposition of the refrigeration system components. 
     
     
         6 . A refrigerating system in accordance with  claim 1  where the total refrigerant mass contained in the system can be accumulated in the receiver. 
     
     
         7 . A refrigeration system in accordance with  claim 1  where the heat rejection device rejects heat to a cooling fluid requiring to be heated.