Monitoring refrigerant in a refrigeration system

• US 20070089438A1
• Filed: 10/21/2005
• Published: 04/26/2007
• Est. Priority Date: 10/21/2005
• Status: Active Grant

• Current Assignee: Copeland Cold Chain LP
• Original Assignee: Emerson Retail Services, Inc. (Emerson Electric Company)
• Inventors: Singh, Abtar, Mitchell, James R.
• Granted Patent: US 7,594,407 B2
• Time in Patent Office: Days
• US Class Current: 62/129
• CPC Class Codes: F25B 2700/04 Refrigerant level
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 2700/21152 at the discharge side of the compressor
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence

Abstract

A method for monitoring refrigerant in a refrigeration system includes calculating a saturation temperature of refrigerant in a refrigeration system based on at least one of a discharge pressure and a discharge temperature of the refrigeration system; calculating an expected refrigerant level based on the saturation temperature; comparing the refrigerant level with the refrigerant level threshold; and generating a leak notification when the receiver refrigerant level is less than the refrigerant level threshold. The method may be executed by a controller or stored in a computer-readable medium.

Claims

1. A method comprising:

receiving a refrigerant level signal that corresponds to a refrigerant level in a refrigeration system;

receiving at least one of a discharge pressure signal that corresponds to a discharge pressure of a compressor of the refrigeration system and a discharge temperature signal that corresponds to a discharge temperature of the compressor;

calculating a saturation temperature of refrigerant in a refrigeration system based on at least one of a discharge pressure and a discharge temperature of said refrigeration system;

calculating an expected refrigerant level based on said saturation temperature;

comparing a refrigerant level of said refrigeration system with said expected refrigerant level; and

generating a leak notification when said refrigerant level is less than said refrigerant level threshold.

2. The method of claim 1, further comprising receiving said refrigerant level from a refrigerant level sensor that generates a refrigerant level signal.

3. The method of claim 1, further comprising receiving said discharge pressure from a discharge pressure sensor that generates a discharge pressure signal.

4. The method of claim 1, further comprising receiving said discharge temperature from a discharge temperature sensor that generates a discharge temperature signal.

5. The method of claim 1, further comprising:

receiving an ambient temperature from an ambient temperature sensor that generates an ambient temperature signal; and

calculating a temperature difference between said saturation temperature and said ambient temperature;

wherein said expected refrigerant level is calculated based on said difference.

6. The method of claim 1, further comprising receiving refrigerant type data, wherein said calculating said saturation temperature is based on said refrigerant type data.

7. The method of claim 1, further comprising:

monitoring said refrigerant level for a predetermined initial period;

generating a refrigerant level model based on said monitoring;

calculating said expected refrigerant level based on said refrigerant level model;

calculating a refrigerant level average over a predetermined period;

comparing said refrigerant level average to said expected refrigerant level; and

generating said leak notification when a difference between said refrigerant level average and said expected refrigerant level is greater than a predetermined refrigerant level difference threshold.

8. The method of claim 7, further comprising:

monitoring said difference between said refrigerant level average and said expected refrigerant level;

wherein said generating said leak notification occurs when said difference between said receiver refrigerant level average and said expected refrigerant level increases over a predetermined monitoring period.

9. A controller that executes the method of claim 1.

10. A controller that executes the method of claim 2.

11. A controller that executes the method of claim 3.

12. A controller that executes the method of claim 4.

13. A controller that executes the method of claim 5.

14. A controller that executes the method of claim 6.

15. A controller that executes the method of claim 7.

16. A controller that executes the method of claim 8.

17. A computer-readable medium having computer-executable instructions for performing the method of claim 1.

18. A computer-readable medium having computer-executable instructions for performing the method of claim 2.

19. A computer-readable medium having computer-executable instructions for performing the method of claim 3.

20. A computer-readable medium having computer-executable instructions for performing the method of claim 4.

21. A computer-readable medium having computer-executable instructions for performing the method of claim 5.

22. A computer-readable medium having computer-executable instructions for performing the method of claim 6.

23. A computer-readable medium having computer-executable instructions for performing the method of claim 7.

24. A computer-readable medium having computer-executable instructions for performing the method of claim 8.