Low pressure refrigeration system

Claim 1

In a refrigeration system having an evaporator and operative to overfeed the evaporator with liquid refrigerant in excess of that evaporated, a compressor, a suction line connecting the return side of said evaporator with the suction inlet of said compressor, an accumulator tank interposed in said suction line operative to collect liquid refrigerant overfeed passing through the evaporator while permitting gaseous refrigerant to return to the compressor, a condenser connected to the outlet of said compressor operative to cool and liquify compressed refrigerant gas received from the compressor, and a system connected to the accumulator and the evaporator for recirculating the liquid refrigerant overfeed collected in the accumulator including a pair of pumper drums connected to said accumulator tank for alternately receiving liquid refrigerant therefrom by gravity, and means supplied from the outlet of the compressor for alternately pressurizing said pumper drums for pumping the liquid refrigerant therein to the evaporator, the improvement comprising: means including a pressure reducing connection and a pressure control valve connected to receive and operative to reduce the pressure of all of said refrigerant from the condenser to a predetermined pressure to provide a stream of primary make-up pressurized refrigerant, and further including means for carrying all of said stream of primary make-up pressurized refrigerant to said pumper drums, combining said stream with overfeed liquid refrigerant in said pumper drums and utilizing said stream for alternately pressurizing said pumper drums for feeding refrigerant to said evaporator.