Injection System and Method for Refrigeration System Compressor

Abstract

A refrigeration system can incorporate a cooling-liquid injection system that can inject a cooling liquid into an intermediate-pressure location of the compressor. The cooling liquid can absorb the heat of compression during the compression of the refrigerant flowing therethrough. The refrigeration system can include an economizer system that injects a refrigerant vapor into an intermediate-pressure location of the compressor in conjunction with the injection of the cooling liquid. A refrigeration system can include a liquid-refrigerant injection system that can inject liquid refrigerant into an intermediate-pressure location of the compressor. The injected liquid refrigerant can reduce the discharge temperature of the refrigerant. The liquid-refrigerant injection system can be used with the cooling-liquid injection system and/or the economizer system.

1 . A refrigeration system comprising a compressor having a suction port, a discharge port, a first passageway, and a second passageway, said compressor compressing a refrigerant and a single-phase liquid flowing therethrough to a discharge pressure greater than a suction pressure, said first passageway through which said refrigerant in a predominantly liquid phase can be injected into a first intermediate-pressure location at a first pressure, said second passageway through which said single-phase liquid can be injected into a second intermediate-pressure location at a second pressure, said first pressure is greater than said second pressure and said first and second pressures are both greater than said suction pressure and are both less than said discharge pressure. 
   
   
       2 . The refrigeration system of  claim 1 , further comprising:
 a first throttle device actively controlling the flow of said refrigerant into said first intermediate-pressure location, said first throttle device reducing a pressure of said refrigerant to lower than said discharge pressure and greater than said first pressure thereby injecting said refrigerant in said predominantly liquid phase into said first intermediate-pressure location, and said refrigerant changing to a predominantly vapor phase inside said compressor; and   a second throttle device actively controlling the flow of said single-phase liquid into said second intermediate-pressure location, said second throttle device reducing a pressure of said single-phase liquid to lower than said discharge pressure and greater than said second pressure thereby injecting said single-phase liquid into said second intermediate-pressure location.   
   
   
       3 . The refrigeration system of  claim 2 , wherein said first and second throttle devices are each responsive to a change in a discharge temperature of said compressor. 
   
   
       4 . The refrigeration system of  claim 3 , wherein said first throttle device opens at a higher discharge temperature than said second throttle device such that said single-phase liquid begins flowing into said second intermediate-pressure location at a lower discharge temperature than when said refrigerant in said predominantly liquid phase begins flowing into said first intermediate-pressure location. 
   
   
       5 . The refrigeration system of  claim 2 , wherein said first and second throttle devices are independently operable to stop all flow of said refrigerant and said single-phase liquid into said first and second intermediate-pressure locations respectively. 
   
   
       6 . The refrigeration system of  claim 1 , further comprising:
 a separator separating said refrigerant in a predominantly gas phase and said single-phase liquid;   a first flow path communicating with said separator and said first passageway and through which a first stream of refrigerant from said separator flows and is injected into said first intermediate-pressure location of said compressor, said first stream being said refrigerant in said predominantly liquid phase when injected into said first intermediate-pressure location;   a second flow path from said separator to said second passageway and through which a second stream of predominantly said single-phase liquid from said separator flows and is injected into said second intermediate-pressure location of said compressor;   a third flow path extending from said separator to said suction port, said third flow path being a main refrigerant flow path and receiving a third stream of refrigerant from said separator, said first flow path extending from said third flow path to said first passageway;   a main throttle device disposed in said third flow path downstream of a location where said first flow path extends from said third flow path, said main throttle device reducing a pressure of said third stream flowing therethrough;   an evaporator in said third flow path downstream of said main throttle device, said evaporator transferring heat into said third stream flowing therethrough; and   a heat exchanger disposed in first and second sections of said third flow path with said first and second sections in heat-transferring relation with one another through said heat exchanger, said first section being upstream of said main throttle device, said second section being downstream of said evaporator and upstream of said suction port, and said heat exchanger transferring heat from said third stream flowing through said first section into said third stream flowing through said second section.   
   
   
       7 . The refrigeration system of  claim 6 , further comprising a gas cooler upstream of said main throttle device cooling refrigerant flowing through said third flow path. 
   
   
       8 . The refrigeration system of  claim 1 , further comprising:
 a heat exchanger reducing a temperature of said single-phase liquid and exhausting compression heat from the system; and   a throttle device between said heat exchanger and said second passageway reducing a pressure of said single-phase liquid to lower than said discharge pressure and greater than said second pressure thereby injecting said single-phase liquid into said second intermediate-pressure location.   
   
   
       9 . The refrigeration system of  claim 1 , wherein said compressor includes a shell defining an exterior periphery of said compressor and said refrigerant flowing into said first intermediate-pressure location is in a predominantly liquid phase when passing through said shell. 
   
   
       10 . The refrigeration system of  claim 1 , wherein said single-phase liquid flows into said second passageway solely due to a pressure difference between said separator and said second pressure. 
   
   
       11 . The refrigeration system of  claim 1 , wherein said single-phase liquid is a lubricant. 
   
   
       12 . The refrigeration system of  claim 1 , wherein said compressor further comprises at least two compression members intermeshed therein with compression cavities formed therebetween and said first and second intermediate-pressure locations are different ones of said cavities. 
   
   
       13 . The refrigeration system of  claim 1 , further comprising:
 a flow path extending from said discharge port to said suction port, said flow path being a main refrigerant flow path, said flow path including first and second sections wherein refrigerant in said first section is at a higher pressure than refrigerant in said second section; and   a heat exchanger disposed in said first and second sections of said flow path with said first and second sections in heat-transferring relation with one another through said heat exchanger, said heat exchanger transferring heat from refrigerant in said first section to refrigerant in said second section.   
   
   
       14 . A refrigeration system comprising:
 a compressor having a suction port, a discharge port, and a first passageway, said compressor compressing a refrigerant and a single-phase liquid flowing therethrough to a discharge pressure greater than a suction pressure, said first passageway through which said refrigerant in a predominantly liquid phase and said single-phase liquid can be injected into a first intermediate-pressure location at a first pressure, said first pressure is greater than said suction pressure and less than said discharge pressure.   
   
   
       15 . The refrigeration system of  claim 14 , further comprising:
 a first active throttle device controlling the flow of said refrigerant into said first passageway, said first throttle device reducing a pressure of said refrigerant to lower than said discharge pressure and greater than said first pressure thereby injecting said refrigerant in said predominantly liquid phase into said first intermediate-pressure location due to the pressure difference; and   a second active throttle device controlling the flow of said single-phase liquid into said first passageway, said second throttle device reducing a pressure of said single-phase liquid to lower than said discharge pressure and greater than said first pressure thereby injecting said single-phase liquid into said first intermediate-pressure location due to the pressure difference.   
   
   
       16 . The refrigeration system of  claim 15 , wherein at least one of said first and second throttle devices is responsive to a discharge temperature of said compressor. 
   
   
       17 . The refrigeration system of  claim 16 , wherein both of said first and second throttle devices regulate flow therethrough based on said discharge temperature of said compressor. 
   
   
       18 . The refrigeration system of  claim 17 , wherein said first throttle device opens at a higher discharge temperature than said second throttle device such that said single-phase liquid begins flowing into said first intermediate-pressure location at a lower temperature than when said refrigerant in said predominantly liquid phase begins flowing into said first intermediate-pressure location. 
   
   
       19 . The refrigeration system of  claim 15 , wherein at least one of said refrigerant in said predominantly liquid phase and said single-phase liquid is injected into said first intermediate-pressure location due solely to said associated pressure difference. 
   
   
       20 . The refrigeration system of  claim 19 , wherein both of said refrigerant in said predominantly liquid phase and said single-phase liquid are injected into said first intermediate-pressure location due solely to said associated pressure difference. 
   
   
       21 . The refrigeration system of  claim 15 , wherein said first throttle device reduces a pressure of said refrigerant thereby changing said refrigerant from a predominantly gaseous phase to said predominantly liquid phase across said first throttle device. 
   
   
       22 . The refrigeration system of  claim 15 , wherein said compressor includes a shell defining an exterior periphery of said compressor and refrigerant flowing into said first passageway is in said predominantly liquid phase when passing through said shell. 
   
   
       23 . The refrigeration system of  claim 14 , wherein said single-phase liquid is a lubricant. 
   
   
       24 . The refrigeration system of  claim 14 , wherein said compressor further comprises at least two compression members intermeshed therein with compression cavities formed therebetween and said first intermediate-pressure location is one of said cavities. 
   
   
       25 . The refrigeration system of  claim 14 , further comprising:
 a separator separating said refrigerant in a predominantly gas phase and said single-phase liquid;   a first flow path extending from said separator to said first passageway and through which refrigerant from said separator flows and is injected into said first passageway in said predominantly liquid phase;   a second flow path communicating with said separator and said first passageway and through which said single-phase liquid from said separator flows and is injected into said first passageway;   a first check valve in said first flow path only allowing flow from said first flow path toward said first passageway; and   a second check valve in said second flow path only allowing flow from said second flow path toward said first passageway.   
   
   
       26 . The refrigeration system of  claim 14 , further comprising;
 a flow path extending from said discharge port to said suction port, said flow path being a main refrigerant flow path, said flow path including first and second sections wherein refrigerant in said first section is at a higher pressure than refrigerant in said second section; and   a heat exchanger disposed in said first and second sections of said flow path with said first and second sections in heat-transferring relation with one another through said heat exchanger, said heat exchanger transferring heat from refrigerant in said first section to refrigerant in said second section.