REFRIGERATION MONITORING SYSTEM AND METHOD

• US 20090071175A1
• Filed: 03/24/2008
• Published: 03/19/2009
• Est. Priority Date: 09/19/2007
• Status: Active Grant

• Current Assignee: Copeland Corporation LLC (Emerson Electric Company)
• Original Assignee: Emerson Climate Technologies Incorporated (Emerson Electric Company)
• Inventors: Pham, Hung M.
• Granted Patent: US 8,393,169 B2
• Time in Patent Office: Days
• US Class Current: 62/129
• CPC Class Codes: F25B 2700/04 Refrigerant level
• CPC Class Codes: F25B 2700/151 of the compressor motor
• CPC Class Codes: F25B 2700/2116 of a condenser
• CPC Class Codes: F25B 2700/21163 of the refrigerant at the outlet of the condenser
• CPC Class Codes: F25B 39/04 Condensers
• CPC Class Codes: F25B 45/00 Arrangements for charging or discharging refrigerant
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems

Abstract

A system is provided and may include a compressor having a motor and a refrigeration circuit including an evaporator and a condenser fluidly coupled to the compressor. The system may further include a first sensor producing a signal indicative of one of current and power drawn by the motor, a second sensor producing a signal indicative of a saturated condensing temperature, and a third sensor producing a signal indicative of a liquid-line temperature. Processing circuitry may processes the current or power signal to determine a derived condenser temperature and may compare the derived condenser temperature to the saturated condensing temperature received from the second sensor to determine a subcooling associated with a refrigerant charge level of the refrigeration circuit.

Claims

1. A system comprising:

a compressor having a motor;

a refrigeration circuit including an evaporator and a condenser fluidly coupled to said compressor;

a first sensor producing a signal indicative of one of current and power drawn by said motor;

a second sensor producing a signal indicative of a saturated condensing temperature;

a third sensor producing a signal indicative of a liquid-line temperature; and

processing circuitry processing said current or power signal to determine a derived condenser temperature and comparing said derived condenser temperature to said saturated condensing temperature received from said second sensor to determine a subcooling associated with a refrigerant charge level of said refrigeration circuit.

2. The system of claim 1, wherein said second sensor is a temperature sensor.

3. The system of claim 2, wherein said second sensor is positioned substantially at a mid point of a refrigeration circuit of said condenser.

4. The system of claim 1, wherein said second sensor is a pressure sensor.

5. The system of claim 4, wherein said second sensor is positioned at one of an inlet or an outlet of said condenser.

6. The system of claim 1, wherein said processing circuitry selects between data from said second sensor and said derived condenser temperature for monitoring at least one of said compressor and said refrigeration circuit based on said charge of said refrigeration circuit.

7. The system of claim 6, wherein said processing circuitry selects between data from said second sensor and said derived condenser temperature after a steady-state stabilization period or a pre-determined amount of time after start-up of said compressor.

8. The system of claim 6, wherein said processing circuitry monitors at least one of said compressor and said refrigeration circuit using said data from said second sensor when said charge of said refrigeration circuit is within a predetermined charge range.

9. The system of claim 7, wherein said processing circuitry monitors at least one of said compressor and said refrigeration circuit based on said derived condenser temperature when said charge of said refrigeration circuit is less than or exceeds said predetermined charge range by a predetermined amount.

10. The system of claim 9, wherein said predetermined charge range is determined based on information from said first sensor.

11. The system of claim 9, wherein said predetermined charge range is determined based on information from said second sensor.

12. The system of claim 1, wherein said processing circuitry declares compressor or system faults based on the difference between said second sensor and the derived condenser temperature

13. The system of claim 1, wherein said processing circuitry diagnoses sensor faults based on the order of said derived condenser temperature, said second sensor, and said third sensor.

14. A method comprising:

detecting a temperature of a condenser;

detecting a liquid-line temperature of fluid circulating within a system;

communicating said detected condenser temperature and said detected liquid-line temperature to processing circuitry;

deriving a temperature of said condenser using non-measured operating parameters at said processing circuitry;

calculating a first subcooling value with said detected condenser temperature;

calculating a second subcooling value with said derived condenser temperature;

comparing said first and second subcooling values at said processing circuitry; and

declaring one of an overcharge condition, an undercharge condition, and an adequate-charge condition.

15. The method of claim 14, wherein said overcharge condition is declared when said first subcooling value is less than said second subcooling value by a predetermined amount.

16. The method of claim 14, wherein said undercharge condition is declared when said first subcooling value is greater than said second subcooling value by a predetermined amount.

17. The method of claim 14, wherein said adequate-charge condition is declared when said first subcooling value is within a predetermined range of said second subcooling value.

18. The method of claim 14, wherein said detecting a liquid-line temperature includes detecting a temperature of liquid exiting said condenser.

19. The method of claim 14, wherein said deriving said condenser temperature includes referencing a compressor map.

20. The method of claim 19, wherein said referencing said compressor map includes referencing one of current and power drawn by a compressor on a compressor map of current or power versus condenser temperature.

21. The method of claim 14, further comprising verifying said detected condenser temperature by comparing said detected condenser temperature to said derived condenser temperature.

22. The method of claim 21, further comprising monitoring a refrigeration system using said detected condenser temperature if said detected condenser temperature is within a predetermined range of said derived condenser temperature.

23. The method of claim 21, further comprising calibrating said derived condenser temperature following verification of said detected condenser temperature.

24. The method of claim 23, further comprising comparing said calibrated condenser temperature to said detected condenser temperature to verify a charge of a refrigeration system.

25. The method of claim 14, further comprising continuously monitoring said detected condenser temperature by continuously comparing said detected condenser temperature to said derived condenser temperature.

26. A method comprising:

detecting a temperature of a condenser;

communicating said temperature to processing circuitry;

deriving a temperature of said condenser using non-measured operating parameters at said processing circuitry;

comparing said detected condenser temperature to said derived condenser temperature at said processing circuitry; and

declaring a compressor fault condition if said detected condenser temperature deviates from said derived condenser temperature by a predetermined amount.

27. The method of claim 26, wherein said compressor fault includes at least one of a bearing failure, a motor defect, and a bad capacitor when said detected condenser temperature is less than said derived condenser temperature by said predetermined amount.

28. The method of claim 26, wherein said compressor fault includes at least one of capacity loss, an internal leak, or a faulty seal when said detected condenser temperature is greater than said derived condenser temperature by said predetermined amount.

29. The method of claim 26, wherein said deriving said condenser temperature includes referencing a compressor map.

30. The method of claim 29, wherein said referencing said compressor map includes referencing one of current and power drawn by a compressor on a compressor map of current or power versus condenser temperature.

31. The method of claim 26, further comprising monitoring a refrigeration system using said detected condenser temperature if said detected condenser temperature is within a predetermined range of said derived condenser temperature.

32. The method of claim 26, further comprising continuously monitoring said detected condenser temperature by continuously comparing said detected condenser temperature to said derived condenser temperature.