System and method for monitoring a condenser of a refrigeration system

• US 7,490,477 B2
• Filed: 04/27/2004
• Issued: 02/17/2009
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: Copeland Cold Chain LP
• Original Assignee: Emerson Retail Services, Inc. (Emerson Electric Company)
• Inventors: Woodworth, Stephen T, Singh, Abtar, Mathews, Thomas J
• Primary Examiner(s): Norman; Marc E
• Application Number:
  US10/833,259
• Publication Number:
  US 20040261431A1
• Time in Patent Office: 1,757 Days
• Field of Search: 621/26, 621/27, 621/29, 621/30, 622/283, 622/29, 622/30, 165/11.1, 165/11.2, 236/51.94
• US Class Current: 62/129
• CPC Class Codes: F25B 2400/075 with parallel compressors
• CPC Class Codes: F25B 2400/22 Refrigeration systems for supermarkets
• CPC Class Codes: F25B 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2600/07 Remote controls
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence

Abstract

A system for monitoring a remote refrigeration system includes a plurality of sensors that monitor parameters of components of the refrigeration system and a communication network that transfers signals generated by each of the plurality of sensors. A management center receives the signals from the communication network and processes the signals to determine an operating condition of at least one of the components. The management center generates an alarm based on the operating condition.

Claims

1. A system comprising:

an ambient temperature sensor that generates an ambient temperature signal corresponding to an ambient temperature;

a condenser sensor, corresponding to a condenser of a refrigeration system, that generates at least one of a condenser temperature signal and a condenser pressure signal;

a communication network that transfers said signals generated by said ambient temperature sensor and said condenser sensor; and

a management center processing said signals from said communication network and analyzing a trend in said signals over a predetermined time period by determining a condenser temperature based on at least one of said condenser temperature signal and said condenser pressure signal, calculating an average difference between said condenser temperature and said ambient temperature over said predetermined time period, and comparing said average difference with a predetermined threshold, said management center generating an alarm indicating performance of said condenser when said average difference is greater than said predetermined threshold.

2. The system of claim 1, wherein said processing said signals includes determining whether each of said signals is within a useful range, determining whether each of said signals is dynamic and determining whether each of said signals is valid.

3. The system of claim 1, further comprising a temperature sensor that monitors a temperature of a refrigerant flowing through said refrigeration system and that generates a temperature signal.

4. The system of claim 3, wherein said management center calculates a pressure, a density and an enthalpy of said refrigerant based on said temperature and based on whether said refrigerant is in one of a saturated liquid phase and a saturated vapor phase.

5. The system of claim 1, further comprising a pressure sensor that monitors a pressure of a refrigerant flowing through said refrigeration system and that generates a pressure signal.

6. The system of claim 5, wherein said management center calculates a temperature, a density and an enthalpy of said refrigerant based on said pressure and based on whether said refrigerant is in one of a saturated liquid phase and a saturated vapor phase.

7. The system of claim 1, further comprising:

a temperature sensor that monitors a temperature of a refrigerant at a suction side of a compressor of said refrigeration system and that generates a temperature signal; and

a pressure sensor that monitors a pressure of a refrigerant at said suction side of said compressor and that generates a pressure signal;

wherein said management center determines an occurrence of a floodback event based on said temperature signal and said pressure signal.

8. The system of claim 7, wherein said management center determines a superheat temperature of said refrigerant based on said temperature signal and said pressure signal and observes a pattern of said superheat over a time period to determine whether said floodback event has occurred.

9. The system of claim 1, further comprising:

a temperature sensor that monitors a temperature of a refrigerant at a discharge side of a compressor of said refrigeration system and that generates a temperature signal; and

a pressure sensor that monitors a pressure of a refrigerant at said discharge side of said compressor and that generates a pressure signal;

wherein said management center determines an occurrence of a floodback event based on said temperature signal and said pressure signal.

10. The system of claim 9, wherein said management center determines a superheat temperature of said refrigerant based on said temperature signal and said pressure signal and observes a pattern of said superheat over a time period to determine whether said floodback event has occurred.

11. The system of claim 1, further comprising a contactor associated with a component of said refrigeration system that is cycled between an open position and a closed position to selectively operate said component.

12. The system of claim 11, wherein said management center monitors cycling of said contactor and generates an alarm when one of a cycling rate is exceeded and a maximum number of cycles is exceeded.

13. The system of claim 1, further comprising:

a compressor current sensor that generates a compressor current signal; and

a condenser fan current sensor that generates a condenser fan current signal;

wherein said condenser sensor is a condenser pressure sensor and generates said condenser pressure signal and said management center determines an operating condition of said condenser based on said ambient temperature signal, said condenser pressure signal, said compressor current signal and said condenser fan current signal.

14. The system of claim 13, wherein said management center determines a power consumption of said condenser, observes said power consumption over a period of time and selectively generates an alarm based on a pattern of said power consumption.

15. The system of claim 1, wherein said management center determines a plurality of bands that define ranges associated with each of said signals and populates each band based on values of said signals that are observed over a defined time period.

16. The system of claim 15, wherein an alarm is generated when a population of a particular band exceeds a threshold associated with said particular band.

17. The system of claim 1 wherein said predetermined time period is a plurality of days.

18. The system of claim 1 wherein said predetermined time period is a day.

19. The system of claim 1 said alarm being a maintenance alarm indicating that said condenser requires maintenance.

20. The system of claim 19 wherein said maintenance alarm indicates that said condenser is dirty.

21. The system of claim 1, said alarm indicating degraded performance of said condenser.

22. A method comprising:

generating an ambient temperature signal corresponding to an ambient temperature with an ambient temperature sensor;

generating at least one of a condenser temperature signal and a condenser pressure signal with a condenser sensor corresponding to a condenser of a refrigeration system;

transferring said signals generated by said ambient temperature sensor and said condenser sensor over a communication network;

analyzing a trend in said signals over a predetermined time period by determining a condenser temperature based on at least one of said condenser temperature signal and said condenser pressure signal, calculating an average difference between said condenser temperature and said ambient temperature over said predetermined time period, and comparing said average difference with a predetermined threshold;

generating an alarm indicating performance of said condenser when said average difference is greater than said predetermined threshold.

23. The method of claim 22 further comprising determining whether each of said signals is within a useful range, determining whether each of said signals is dynamic and determining whether each of said signals is valid.

24. The method of claim 22 further comprising:

monitoring a temperature of a refrigerant flowing through said refrigeration system; and

generating a temperature signal based on said temperature.

25. The method of claim 24, further comprising calculating a pressure, a density and an enthalpy of said refrigerant based on said temperature and based on whether said refrigerant is in one of a saturated liquid phase and a saturated vapor phase.

26. The method of claim 22, further comprising:

monitoring a pressure of a refrigerant flowing through said refrigeration system; and

generating a pressure signal based on said pressure.

27. The method of claim 26, further comprising calculating a temperature, a density and an enthalpy of said refrigerant based on said pressure and based on whether said refrigerant is in one of a saturated liquid phase and a saturated vapor phase.

28. The method of claim 22, further comprising:

monitoring a temperature of a refrigerant at a suction side of a compressor of said refrigeration system;

generating a temperature signal based on said temperature;

monitoring a pressure of a refrigerant at said suction side of said compressor;

generating a pressure signal based on said pressure; and

determining an occurrence of a floodback event based on said temperature signal and said pressure signal.

29. The method of claim 28, further comprising:

determining a superheat temperature of said refrigerant based on said temperature signal and said pressure signal; and

observing a pattern of said superheat over a time period to determine whether said floodback event has occurred.

30. The system of claim 22, further comprising:

monitoring a temperature of a refrigerant at a discharge side of a compressor of said refrigeration system;

generating a temperature signal based on said temperature; and

monitoring a pressure of a refrigerant at said discharge side of said compressor;

generating a pressure signal based on said pressure; and

determining an occurrence of a floodback event based on said temperature signal and said pressure signal.

31. The method of claim 30, further comprising:

determining a superheat temperature of said refrigerant based on said temperature signal and said pressure signal; and

observing a pattern of said superheat over a time period to determine whether said floodback event has occurred.

32. The method of claim 22, further comprising cycling a contactor associated with a component of said refrigeration system between an open position and a closed position to selectively operate said component.

33. The method of claim 32, further comprising:

monitoring said cycling of said contactor; and

generating an alarm when one of a cycling rate is exceeded and a maximum number of cycles is exceeded.

34. The method of claim 22 wherein said generating at least one of said condenser temperature signal and said condenser pressure signal includes generating said condenser pressure signal, said method further comprising:

generating a compressor current signal based on a compressor current;

generating a condenser fan current signal based on a condenser fan current; and

determining an operating condition of said condenser based on said ambient temperature signal, said condenser pressure signal, said compressor current signal and said condenser fan current signal.

35. The method of claim 34, further comprising:

determining a power consumption of said condenser;

observing said power consumption over a period of time; and

selectively generating an alarm based on a pattern of said power consumption.

36. The method of claim 22, further comprising:

determining a plurality of bands that define ranges associated with each of said signals; and

populating each band based on values of said signals that are observed over a defined time period.

37. The method of claim 36, further comprising generating an alarm when a population of a particular band exceeds a threshold associated with said particular band.

38. The method of claim 22 wherein said predetermined time period is a plurality of days.

39. The method of claim 22 wherein said predetermined time period is a day.

40. The method of claim 22 said alarm being a maintenance alarm indicating that said condenser requires maintenance.

41. The method of claim 39 wherein said maintenance alarm indicates that said condenser is dirty.

42. The system of claim 39, wherein said maintenance alarm indicates that said condenser is dirty.