Refrigeration system

• US 8,181,478 B2
• Filed: 10/02/2006
• Issued: 05/22/2012
• Est. Priority Date: 10/02/2006
• Status: Active Grant

• Current Assignee: Copeland Corporation LLC (Emerson Electric Company)
• Original Assignee: Emerson Climate Technologies Incorporated (Emerson Electric Company)
• Inventors: Ignatiev, Kirill
• Primary Examiner(s): Jules, Frantz
• Assistant Examiner(s): Bauer, Cassey D
• Application Number:
  US11/541,951
• Publication Number:
  US 20080078204A1
• Time in Patent Office: 2,059 Days
• Field of Search: 624/70, 624/73, 625/01, 625/02, 625/12, 625/13, 624/68, 625/05
• US Class Current: 62/468
• CPC Class Codes: F25B 1/10 with multi-stage compression with cascade operation F25B7/00
• CPC Class Codes: F25B 2400/13 Economisers
• CPC Class Codes: F25B 2400/23 Separators
• CPC Class Codes: F25B 31/002 Lubrication
• CPC Class Codes: F25B 40/00 Subcoolers, desuperheaters or superheaters
• CPC Class Codes: F25B 43/02 for separating lubricants from the refrigerant

Abstract

A refrigeration system can incorporate a liquid-injection system that can provide a cooling liquid to 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 circuit that injects a refrigerant vapor into an intermediate-pressure location of the compressor in conjunction with the injection of the cooling liquid. The incorporation of the vapor injection in conjunction with the cooling-liquid injection can advantageously increase the cooling capacity and/or efficiency of the refrigeration system and the performance of the compressor.

Claims

1. A refrigeration system comprising:

a compressor having a suction port, a discharge port, and a first intermediate-pressure port in communication with a first intermediate-pressure location of said compressor, said first intermediate-pressure location having a first intermediate pressure during operation of said compressor;

a refrigerant flowing through said compressor and compressed from a suction pressure to a discharge pressure greater than said suction pressure and having a nominal discharge temperature, said first intermediate pressure being greater than said suction pressure and less than said discharge pressure;

a single-phase cooling liquid received in said first intermediate-pressure port and injected into said first intermediate-pressure location and compressed to said discharge pressure and said nominal discharge temperature, said cooling liquid absorbing heat within said compressor caused by compression of said refrigerant and said cooling liquid;

a separator separating said refrigerant and said cooling liquid and operating at a temperature and pressure approximately equal to said discharge temperature and pressure;

a first heat exchanger receiving a generally refrigerant-free flow of said cooling liquid from said separator and removing heat to reduce a temperature of said cooling liquid;

a throttle device disposed in a flow path between said first heat exchanger and said first intermediate-pressure port and reducing a pressure of said cooling liquid to lower than said discharge pressure and greater than said first intermediate pressure of said first intermediate-pressure location of said compressor,

wherein a fluid injected into said first intermediate-pressure location through said first intermediate-pressure port is substantially said single-phase cooling liquid and a pressure difference between said discharge pressure and said first intermediate pressure causes said single-phase cooling liquid to be injected into said first intermediate-pressure location;

a vapor-injection port on said compressor communicating with a second intermediate-pressure location of said compressor, said second intermediate pressure location having a second intermediate pressure during operation of said compressor greater than said suction pressure and less than said discharge pressure, and wherein a refrigerant stream flows out of said separator and a portion of said refrigerant stream is expanded and injected into said second intermediate pressure location of said compressor through said vapor-injection port in vapor form,

wherein an entirety of said refrigerant stream is expanded through an expansion device and flows into a flash tank wherein a vapor portion of said refrigerant in said flash tank is injected into said compressor through said vapor-injection port.

2. The refrigeration system of claim 1, wherein said compressor is a scroll compressor having at least two compression members intermeshed therein with compression cavities formed therebetween.

3. The refrigeration system of claim 2, wherein said first intermediate-pressure location is a compression cavity formed between said compression members.

4. The refrigeration system of claim 1, wherein said compressor is a single-stage compressor.

5. The refrigeration system of claim 1, wherein said throttle device actively controls flow of said cooling liquid through said flow path.

6. The refrigeration system according to claim 1, wherein said refrigerant is a multi-phase, trans-critical refrigerant and said nominal discharge temperature is greater than a critical temperature of said refrigerant.

7. The refrigeration system of claim 6, wherein said refrigerant and said cooling liquid exit said discharge port and flow directly to said separator.

8. The refrigeration system of claim 1, wherein said single-phase cooling liquid is injected into said first intermediate-pressure location solely due to said pressure difference.

9. A refrigeration system comprising:

a compressor having a suction port, a discharge port, and a first intermediate-pressure port in communication with a first intermediate-pressure location of said compressor, said first intermediate-pressure location having a first intermediate pressure during operation of said compressor;

a refrigerant flowing through said compressor and compressed from a suction pressure to a discharge pressure greater than said suction pressure and having a nominal discharge temperature, said first intermediate pressure being greater than said suction pressure and less than said discharge pressure;

a single-phase cooling liquid received in said first intermediate-pressure port and injected into said first intermediate-pressure location and compressed to said discharge pressure and said nominal discharge temperature, said cooling liquid absorbing heat within said compressor caused by compression of said refrigerant and said cooling liquid;

a separator separating said refrigerant and said cooling liquid and operating at a temperature and pressure approximately equal to said discharge temperature and pressure;

a first heat exchanger receiving a generally refrigerant-free flow of said cooling liquid from said separator and removing heat to reduce a temperature of said cooling liquid;

a throttle device disposed in a flow path between said first heat exchanger and said first intermediate-pressure port and reducing a pressure of said cooling liquid to lower than said discharge pressure and greater than said first intermediate pressure of said first intermediate-pressure location of said compressor,

wherein a fluid injected into said first intermediate-pressure location through said first intermediate-pressure port is substantially said single-phase cooling liquid and a pressure difference between said discharge pressure and said first intermediate pressure causes said single-phase cooling liquid to be injected into said first intermediate-pressure location;

a vapor-injection port on said compressor communicating with a second intermediate-pressure location of said compressor, said second intermediate pressure location having a second intermediate pressure during operation of said compressor greater than said suction pressure and less than said discharge pressure, and wherein a refrigerant stream flows out of said separator and a portion of said refrigerant stream is expanded and injected into said second intermediate pressure location of said compressor through said vapor-injection port in vapor form,

wherein said refrigerant stream flows through a second heat exchanger in heat-transferring relation with said expanded portion of said refrigerant prior to said expanded portion being separated from said refrigerant stream.

10. The refrigeration system of claim 9, wherein said compressor is a scroll compressor having at least two compression members intermeshed therein with compression cavities formed therebetween, and wherein said first intermediate-pressure location is a compression cavity formed between said compression members.

11. The refrigeration system of claim 9, wherein said compressor is a single-stage compressor.

12. The refrigeration system of claim 9, wherein said throttle device actively controls flow of said cooling liquid through said flow path.

13. The refrigeration system according to claim 9, wherein said refrigerant is a multi-phase, trans-critical refrigerant and said nominal discharge temperature is greater than a critical temperature of said refrigerant.

14. The refrigeration system of claim 13, wherein said refrigerant and said cooling liquid exit said discharge port and flow directly to said separator.

15. The refrigeration system of claim 9, wherein said single-phase cooling liquid is injected into said first intermediate-pressure location solely due to said pressure difference.

16. A refrigeration system comprising:

a compressor having a suction port, a discharge port, and at least two intermediate-pressure ports each communicating with a different intermediate-pressure location of said compressor, said compressor compressing a refrigerant and a single-phase cooling liquid flowing therethrough to a discharge pressure greater than a suction pressure;

a separator separating said refrigerant and said cooling liquid;

a first flow path communicating with said separator and a first one of said intermediate-pressure ports and through which a first stream of generally refrigerant-free cooling liquid from said separator flows and is injected into a first intermediate-pressure location of said compressor, said first intermediate-pressure location having a first intermediate pressure during operation of said compressor greater than said suction pressure and less than said discharge pressure, and said cooling liquid absorbing heat within said compressor caused by said compression; and

a second flow path communicating with said separator and a second one of said intermediate-pressure ports and through which a second stream of generally cooling-liquid-free vapor refrigerant flows and is injected into a second intermediate-pressure location of said compressor, said second intermediate-pressure location having a second intermediate pressure during operation of said compressor greater than said suction pressure and less than said discharge pressure,

wherein said first flow path includes a first heat exchanger and a first throttle device, said first heat exchanger removing heat from said first stream thereby reducing a temperature of said first stream, and said first throttle device reducing a pressure of said reduced first stream to lower than said discharge pressure and greater than said first intermediate pressure of said first intermediate-pressure location thereby injecting said first stream into said first intermediate-pressure location due to a pressure difference between said discharge pressure and said first intermediate pressure;

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 generally cooling-liquid-free refrigerant from said separator, said second flow path communicating with said third flow path such that said second stream is a minority portion of said third stream;

a pressure-reducing device disposed in said third flow path reducing a pressure of said third stream to less than said discharge pressure and greater than said second intermediate pressure of said second intermediate-pressure location;

a flash tank in said third steam downstream of said pressure-reducing device, said flash tank operable to allow a portion of said third stream to flash into a two-phase stream of liquid and vapor refrigerant, said second flow path extending from said flash tank to said second intermediate-pressure port such that said second stream is refrigerant vapor from said flash tank and is injected into said second intermediate-pressure location, and a majority portion of said third stream exits said flash tank through said third flow path and can include both liquid and vapor refrigerant.

17. The refrigeration system of claim 16, wherein said separator directly receives said refrigerant and said cooling liquid discharged by said compressor and operates at a temperature and pressure approximately equal to a discharge temperature of said compressor and said discharge pressure.

18. The refrigeration system of claim 16, wherein said compressor is a scroll compressor having at least two compression members intermeshed therein with compression cavities formed therebetween.

19. The refrigeration system of claim 18, wherein said first and second intermediate-pressure locations are each a compression cavity formed between said compression members.

20. The refrigeration system of claim 16, wherein said compressor is a single stage compressor.

21. The refrigeration system according to claim 16, wherein said refrigerant is a multi-phase, trans-critical refrigerant and said compressor discharges said refrigerant at a nominal discharge temperature greater than a critical temperature of said refrigerant.

22. A refrigeration system comprising:

a compressor having a suction port, a discharge port, and at least two intermediate-pressure ports each communicating with a different intermediate-pressure location of said compressor, said compressor compressing a refrigerant and a single-phase cooling liquid flowing therethrough to a discharge pressure greater than a suction pressure;

a separator separating said refrigerant and said cooling liquid;

a first flow path communicating with said separator and a first one of said intermediate-pressure ports and through which a first stream of generally refrigerant-free cooling liquid from said separator flows and is injected into a first intermediate-pressure location of said compressor, said first intermediate-pressure location having a first intermediate pressure during operation of said compressor greater than said suction pressure and less than said discharge pressure, and said cooling liquid absorbing heat within said compressor caused by said compression;

a second flow path communicating with said separator and a second one of said intermediate-pressure ports and through which a second stream of generally cooling-liquid-free vapor refrigerant flows and is injected into a second intermediate-pressure location of said compressor, said second intermediate-pressure location having a second intermediate pressure during operation of said compressor greater than said suction pressure and less than said discharge pressure;

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 generally cooling-liquid-free refrigerant from said separator, said second flow path extending from said third flow path to said second intermediate-pressure port and said second stream is a minority portion of said third stream;

a first heat exchanger through which said second and third flow paths extend in heat-transferring relation, said first heat exchanger transferring heat from said third stream to said second stream;

a pressure-reducing device disposed in said second flow path reducing a pressure of said second stream to less than said discharge pressure and greater than said second intermediate pressure of said second intermediate-pressure location thereby injecting said second stream into said second intermediate-pressure location;

a main throttle device disposed in said third flow path downstream of a location where said second 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 second 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 second heat exchanger, said first section being upstream of said first heat exchanger such that said third stream flowing through said first section flows through said second heat exchanger prior to flowing through said first heat exchanger, said second section being downstream of said evaporator and upstream of said suction port, and said second heat exchanger transferring heat from said third stream flowing through said first section into said third stream flowing through said second section.

23. The refrigeration system of claim 22, wherein said compressor is a scroll compressor having at least two compression members intermeshed therein with compression cavities formed therebetween.

24. The refrigeration system of claim 23, wherein said first and second intermediate-pressure locations are each a compression cavity formed between said compression members.

25. The refrigeration system of claim 22, wherein said compressor is a single stage compressor.

26. The refrigeration system according to claim 22, wherein said refrigerant is a multi-phase, trans-critical refrigerant and said compressor discharges said refrigerant at a nominal discharge temperature greater than a critical temperature of said refrigerant.

27. The refrigeration system of claim 22, wherein said separator directly receives said refrigerant and said cooling liquid discharged by said compressor and operates at a temperature and pressure approximately equal to a discharge temperature of said compressor and said discharge pressure.

28. A refrigeration system comprising:

a compressor having a suction port, a discharge port, and at least two intermediate-pressure ports each communicating with a different intermediate-pressure location of said compressor, said compressor compressing a refrigerant and a single-phase cooling liquid flowing therethrough to a discharge pressure greater than a suction pressure;

a separator separating said refrigerant and said cooling liquid;

a first flow path communicating with said separator and a first one of said intermediate-pressure ports and through which a first stream of generally refrigerant-free cooling liquid from said separator flows and is injected into a first intermediate-pressure location of said compressor, said first intermediate-pressure location having a first intermediate pressure during operation of said compressor greater than said suction pressure and less than said discharge pressure, and said cooling liquid absorbing heat within said compressor caused by said compression;

a second flow path communicating with said separator and a second one of said intermediate-pressure ports and through which a second stream of generally cooling-liquid-free vapor refrigerant flows and is injected into a second intermediate-pressure location of said compressor, said second intermediate-pressure location having a second intermediate pressure during operation of said compressor greater than said suction pressure and less than said discharge pressure;

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 generally cooling-liquid-free refrigerant from said separator, said second flow path communicating with said third flow path such that said second stream is a minority portion of said third stream;

a first pressure-reducing device disposed in said third flow path reducing a pressure of said third stream to less than said discharge pressure and greater than said second intermediate pressure of said second intermediate-pressure location; and

a flash tank in said third steam downstream of said first pressure-reducing device, said flash tank operable to allow a portion of said third stream to flash into a two-phase stream of liquid and vapor refrigerant, said second flow path extending from said flash tank to said second intermediate-pressure port such that said second stream is refrigerant vapor from said flash tank that is injected into said second intermediate-pressure location, and a majority portion of said third stream exits said flash tank through said third flow path and can include both liquid and vapor refrigerant.

29. The refrigeration system of claim 28, further comprising:

a second pressure-reducing device disposed in said third flow path downstream of said flash tank, said second pressure-reducing device reducing a pressure of said third stream flowing therethrough;

an evaporator in said third flow path downstream of said second pressure-reducing 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 first pressure-reducing device such that said third stream flowing through said first section flows through said heat exchanger prior to flowing through said evaporator, 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.

30. The refrigeration system of claim 28, wherein said compressor is a scroll compressor having at least two compression members intermeshed therein with compression cavities formed therebetween, and wherein said first and second intermediate-pressure locations are each a compression cavity formed between said compression members.

31. The refrigeration system of claim 28, wherein said compressor is a single stage scroll compressor.

32. The refrigeration system according to claim 28, wherein said refrigerant is a multi-phase, trans-critical refrigerant and said compressor discharges said refrigerant at a nominal discharge temperature greater than a critical temperature of said refrigerant.

33. The refrigeration system of claim 28, wherein said separator directly receives said refrigerant and said cooling liquid discharged by said compressor and operates at a temperature and pressure approximately equal to a discharge temperature of said compressor and said discharge pressure.