High efficiency refrigeration system and cycle

Abstract

A high efficiency air conditioning and refrigeration system and cycle comprises a vapor compressor and two independent ejectors operatively connected to high and low-pressure sides of the compressor, respectively. The two ejectors reduce the overall pressure ratio of the mechanical vapor compressor resulting in dramatically increased thermodynamic cycle efficiency. As one example of its potential applications for residential, commercial or industrial uses, a 150 ton capacity of a water-cooled chiller designed in accordance with the present invention is predicted to provide the power consumption as low as 0.47 kW/ton, when operated in accordance with the cooling methods of the present invention, which corresponds to 7.47 of Coefficient of Performance (COP).

1 . A refrigeration system using a refrigerant cycled therethrough, said refrigeration system comprising:
 a vapor compressor comprising a low-pressure side and a high-pressure side;   a first ejector in operative communication with the high-pressure side of the vapor compressor, wherein the first ejector boosts the pressure of vapor-phase refrigerant received from the vapor compressor using a pressurized sub-cooled liquid mixed with said vapor-phase refrigerant, and further wherein said first ejector discharges a vapor stream having an elevated pressure that is greater than the pressure of either the input vapor-phase refrigerant received from the vapor compressor or the pressurized sub-cooled liquid;   a condenser for converting the vapor stream discharged from the first ejector into a liquid-phase refrigerant;   a heat exchanger for converting the liquid-phase refrigerant into a sub-cooled liquid-phase refrigerant;   a second ejector in operative communication with the low-pressure side of the vapor compressor, the second ejector boosts the pressure of vapor-phase refrigerant using at least a portion of the sub-cooled liquid-phase refrigerant discharged from the heat exchanger mixed with said vapor-phase refrigerant, and the refrigerant from the second ejector is provided through the heat exchanger for subcooling the liquid-phase refrigerant to the low-pressure side of the vapor compressor.   
     
     
         2 . The refrigeration system as claimed in  claim 1 , further comprising:
 a primary evaporator in operative communication with a discharge outlet of the second ejector for evaporating the mixed-phase refrigerant into a vapor-phase refrigerant; and   a secondary evaporator in operative communication with the heat exchanger for evaporating the sub-cooled liquid-phase refrigerant into a vapor-phase refrigerant that is provided to an input of the second ejector for mixing with said at least a portion of the sub-cooled liquid phase refrigerant therein.   
     
     
         3 . The refrigeration system as claimed in  claim 2 , further comprising an expansion valve operatively positioned between the heat exchanger and the secondary evaporator for expanding the liquid-phase refrigerant provided to the secondary evaporator. 
     
     
         4 . The refrigeration system as claimed in  claim 2 , wherein the vapor-phase refrigerant evaporated by the primary evaporator is superheated through the heat exchanger before being provided to the low-pressure side of the vapor compressor. 
     
     
         5 . The refrigeration system as claimed in  claim 1 , further comprising a centrifugal pump for pressurizing at least a portion of the sub-cooled liquid-phase refrigerant discharged from the heat exchanger, wherein said pressurized sub-cooled liquid is provided to the first ejector for mixing with vapor-phase refrigerant therein. 
     
     
         6 . The refrigeration system as claimed in  claim 1 , wherein the vapor compressor is a single-stage compressor. 
     
     
         7 . The refrigeration system as claimed in  claim 1 , wherein the vapor compressor is a two-stage compressor with a first compression stage and a second compression stage, said second compression stage operating at a higher pressure than the first compression stage. 
     
     
         8 . The refrigeration system as claimed in  claim 7 , wherein each stage of the vapor compressor is driven by a motor. 
     
     
         9 . The refrigeration system as claimed in  claim 8 , wherein each stage of the vapor compressor includes an impeller operatively connected to the motor for rotation. 
     
     
         10 . The refrigeration system as claimed in  claim 1 , wherein the loads of the first and second ejectors are cooled by at least one of air or water. 
     
     
         11 . The refrigeration system as claimed in  claim 1 , wherein the vapor compressor is a positive displacement compressor. 
     
     
         12 . The refrigeration system as claimed in  claim 1 , wherein the vapor compressor is a centrifugal turbocompressor. 
     
     
         13 . A refrigeration system using a refrigerant cycled therethrough, said refrigeration system comprising:
 a two-stage vapor compressor comprising a first compression stage and a second compression stage, said second compression stage operating at a higher pressure than the first compression stage;   a first high-pressure ejector in operative communication with the second compression stage of the vapor compressor, wherein the first ejector boosts the pressure of vapor-phase refrigerant received from the vapor compressor using a pressurized sub-cooled liquid mixed with said vapor-phase refrigerant, and further wherein said first ejector discharges a vapor stream having an elevated pressure that is greater than the pressure of either the input vapor-phase refrigerant received from the vapor compressor or the pressurized sub-cooled liquid;   a condenser for converting the vapor stream discharged from the first ejector into a liquid-phase refrigerant;   a heat exchanger for converting the liquid-phase refrigerant into a sub-cooled liquid-phase refrigerant;   a centrifugal pump for pressurizing a first portion of the sub-cooled liquid-phase refrigerant discharged from the heat exchanger, wherein said pressurized sub-cooled liquid is provided to the first ejector for mixing with vapor-phase refrigerant therein;   a second low-pressure ejector in operative communication with the first compression stage of the vapor compressor, wherein the second ejector boosts the pressure of vapor-phase refrigerant using a second portion of the sub-cooled liquid-phase refrigerant discharged from the heat exchanger mixed with said vapor-phase refrigerant, and further wherein the second ejector discharges a mixed refrigerant;   a primary evaporator in operative communication with a discharge outlet of the second ejector for evaporating the mixed refrigerant discharged therefrom into a vapor-phase refrigerant; and   a secondary evaporator that evaporates a portion of the second portion of the sub-cooled liquid-phase refrigerant discharged from the heat exchanger into a vapor-phase refrigerant that is provided to an input of the second ejector for mixing with the remainder of said second portion of the sub-cooled liquid-phase refrigerant therein;   wherein the vapor-phase refrigerant discharged from the primary evaporator is provided to the first compression stage of the vapor compressor.   
     
     
         14 . The refrigeration system as claimed in  claim 13 , further comprising an expansion valve operatively positioned between the heat exchanger and the secondary evaporator for expanding the liquid-phase refrigerant provided to the evaporator. 
     
     
         15 . The refrigeration system as claimed in  claim 14 , wherein the vapor-phase refrigerant from the primary evaporator is superheated through the heat exchanger before being provided to the low-pressure side of the vapor compressor. 
     
     
         16 . The refrigeration system as claimed in  claim 14 , wherein the loads of the first and second ejectors are cooled by at least one of air or water. 
     
     
         17 . A refrigeration cycling method comprising:
 providing a mechanical vapor compressor having a low-pressure side and a high-pressure side;   providing a first ejector in operative communication with the high-pressure side of the vapor compressor;   mixing vapor-phase refrigerant discharged from the vapor compressor with a pressurized sub-cooled liquid in the first ejector so as to boost the pressure of the vapor-phase refrigerant to an elevated pressure that is greater than the pressure of either the input vapor-phase refrigerant received from the vapor compressor or the pressurized sub-cooled liquid;   converting the vapor stream discharged from the first ejector into a sub-cooled liquid-phase refrigerant;   providing a second ejector in operative communication with the low-pressure side of the vapor compressor;   mixing vapor-phase refrigerant with the sub-cooled liquid-phase refrigerant in the second ejector to provide a mixed vapor-phase refrigerant having an elevated pressure;   evaporating the mixed-phase refrigerant into a vapor-phase refrigerant that is provided through the heat exchanger to the mechanical vapor compressor;   superheating the vapor-phase refrigerant; and   providing the superheated vapor-phase refrigerant to the low-pressure side of the vapor compressor.   
     
     
         18 . The refrigeration cycling method as claimed in  claim 17 , wherein the vapor compressor is a two-stage compressor with a first compression stage and a second compression stage, said second compression stage operating at a higher pressure than the first compression stage. 
     
     
         19 . The refrigeration cycling method as claimed in  claim 17 , wherein each of the first and second ejectors comprises a two-phase ejector. 
     
     
         20 . The refrigeration cycling method as claimed in  claim 17 , further comprising the step of cooling the loads of the first and second ejectors by at least one of air or water.