System and method for detecting decreased performance in a refrigeration system

• US 20060042276A1
• Filed: 08/25/2004
• Published: 03/02/2006
• Est. Priority Date: 08/25/2004
• Status: Active Grant

• Current Assignee: York International Corporation (Johnson Controls International plc)
• Original Assignee: York International Corporation (Johnson Controls International plc)
• Inventors: Hansen, John C., Doll, Martin Luther Jr.
• Granted Patent: US 8,109,104 B2
• Time in Patent Office: Days
• US Class Current: 62/129
• CPC Class Codes: F25B 2600/19 Refrigerant outlet condenser temperature
• CPC Class Codes: F25B 2700/04 Refrigerant level
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 2700/195 of the condenser
• CPC Class Codes: F25B 2700/2106 of fresh outdoor air
• CPC Class Codes: F25B 2700/21163 of the refrigerant at the outlet of the condenser
• CPC Class Codes: F25B 2700/21173 at the outlet
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence

Abstract

Systems and methods are provided for detecting performance degradation in a refrigeration system. Specifically, the present invention provides systems and methods for detecting, at a very early stage, a low refrigerant charge and degradation in condenser performance of a refrigeration system.

Claims

1. A chiller system comprising:

a compressor, a condenser, and an evaporator interconnected by a refrigerant liquid line and forming a closed refrigerant circuit;

a plurality of sensors for sensing system parameters and transmitting data signals to a control;

a control having a microprocessor and computer-readable instructions for storing a reference map of data relating to system parameters, for receiving and processing data signals from the sensors, for comparing the processed data signals to the data of the reference map, for detecting a system defect based upon the compared data, and;

an interface board communicably connected to the control for generating at least one alert and transmitting the at least one alert to a user interface.

2. The chiller system of claim 1 wherein the plurality of sensors comprises at least one sensor for gathering data relating to the refrigerant liquid line temperature, at least one sensor for gathering data relating to the discharge pressure of the compressor, and wherein the detected system defect relates to low refrigerant charge.

3. The chiller system of claim 2, wherein the plurality of sensors further comprises at least one ambient temperature sensor and a leaving chilled liquid temperature sensor, and wherein the detected system defect further includes high discharge pressure relating to faulty performance of the condenser or a condenser-related component of the system.

4. The chiller system of claim 2, wherein the at least one sensor for gathering data relating to the discharge pressure of the compressor is a pressure transducer, and the at least one sensor for gathering data relating to the refrigerant liquid line is a thermistor.

5. The chiller system of claim 1 wherein the plurality of sensors comprise at least one sensor for gathering data relating to the refrigerant liquid line temperature, at least one sensor for gathering data relating to the condensing pressure of the condenser, and wherein the detected system defect relates to low refrigerant charge.

6. The chiller system of claim 5, wherein the plurality of sensors further comprises at least one ambient temperature sensor and a leaving chilled liquid temperature sensor, and wherein the detected system defect further includes high discharge pressure relating to faulty performance of the condenser or a condenser-related component of the system.

7. The chiller system of claim 5, wherein the at least one sensor for gathering data relating to the discharge pressure of the compressor is a pressure transducer, and the at least one sensor for gathering data relating to the refrigerant liquid line is a thermistor.

8. The chiller system of claim 1, wherein the plurality of sensors comprise at least one sensor for gathering data relating to the refrigerant liquid line temperature, at least one sensor for gathering data relating to the condensing temperature of the condenser, and wherein the detected system defect relates to low refrigerant charge.

9. The chiller system of claim 8, wherein the plurality of sensors further comprises at least one ambient temperature sensor and a leaving chilled liquid temperature sensor, and wherein the detected system defect further includes high discharge pressure relating to faulty performance of the condenser or a condenser-related component of the system.

10. The chiller system of claim 8, wherein the at least one sensor for gathering data relating to the refrigerant liquid line is a thermistor, and wherein the at least one sensor for gathering data relating to the discharge pressure of the compressor is a temperature thermistor located in the condensing section of the condensor, and wherein the data relating to the condensing pressure is the temperature of condensed liquid refrigerant in the condenser.

11. A control system for monitoring system parameters and detecting system defects in a chiller system having a compressor, a condensor, and an evaporator interconnected by a refrigerant liquid line and forming a closed refrigeration circuit, the control system comprising:

a first algorithm for monitoring parameters relating to low refrigerant charge, detecting low refrigerant charge at a very early stage, and generating an alert concerning low refrigerant charge; and

a second one algorithm for monitoring the parameters relating to the performance of the condenser, detecting faulty condenser performance at a very early stage, and generating an alert concerning faulty condenser performance.

12. The control system of claim 11 wherein the first algorithm for monitoring parameters relating to low refrigerant charge and the second algorithm each include an initialization stage for storing at least one reference map containing reference values relating to the monitored parameters at specific operating conditions.

13. The control system of claim 11, wherein the first algorithm includes a low refrigerant charge warning threshold that is based on the comparison of actual subcooling versus a reference subcooling value stored in an operating map of the control, and wherein the second algorithm includes a faulty condenser performance warning threshold that is based on the comparison of actual saturated refrigerant temperature versus a reference saturated refrigerant temperature stored in an operating map of the control.

14. The control system of claim 13, wherein the low refrigerant charge threshold is reached when the comparison of actual subcooling to a reference subcooling value is between about 90% to about 20%.

15. The control system of claim 13, wherein the condenser includes a water-cooled condenser, and wherein the faulty condenser performance threshold is reached when the actual saturated refrigerant temperature is between about 6 degrees F. to about 9 degrees F. greater than the reference saturated refrigerant temperature.

16. The control system of claim 13, wherein the condenser includes an air-cooled condenser, and wherein the faulty condenser performance threshold is reached when the actual saturated refrigerant temperature is between about 8 degrees F. to about 12 degrees F. greater than the reference saturated refrigerant temperature.

17. The control system of claim 11 wherein the first algorithm for monitoring parameters relating to refrigerant charge and the second algorithm for monitoring parameters relating to the performance of the condenser each include a startup/shutdown stage for shutting down the system and maintaining the system in a non-operative state under selected shutdown conditions.

18. The control system of claim 17 wherein the selected shutdown conditions are selected from:

a comparison of actual subcooling to a reference subcooling value wherein the resulting ratio is less than 40%; and

, a comparison of actual saturated condensing temperature to a reference saturated condensing temperature wherein the resulting ratio is less than 40%.

19. A method of providing monitoring and control of system parameters in a chiller system, the method comprising the steps of:

storing reference data relating to parameters associated with proper refrigerant charge at various load conditions;

providing a plurality of sensors for gathering data concerning operating parameters associated with proper refrigerant charge;

operating the chiller system and gathering data from the sensors relating to proper refrigerant charge at actual load conditions;

comparing the gathered data from the sensors to the reference data; and

generating a low refrigerant charge alert if the gathered data does not fall within a predetermined range of the corresponding reference data.

20. The method of claim 19, wherein the reference data and gathered data are comprised of refrigerant line temperature and at least one of discharge pressure, condensing pressure, and condensing temperature.

21. The method of claim 19, wherein the gathered data is actual subcooling, the reference data is a reference subcooling value, and wherein the predetermined range for the low refrigerant alert is between about 90% to about 20%.

22. The method of claim 19, further comprised of the step of shutting the system down if the gathered data does not fall within a predetermined minimum threshold based on comparison to the corresponding reference data.

23. The method of claim 19 further comprising the steps of

storing reference data relating to parameters associated with proper condenser performance at various load conditions and ambient temperatures;

providing a plurality of sensors for gathering data concerning operating parameters associated with condenser performance;

operating the chiller system and gathering data from the sensors relating to condenser performance at actual load conditions and ambient temperatures;

comparing the gathered data from the sensors to the reference data; and

generating a condenser fault alert if the gathered data does not fall within a predetermined range of the corresponding reference data.

24. The method of claim 23, wherein the reference data relating to parameters associated with proper condenser performance and gathered data from the sensors relating to condenser performance are comprised of ambient temperature, leaving liquid line temperature, and at least one of discharge pressure, condensing pressure, and condensing temperature.

25. The method of claim 24, wherein the gathered data from the sensors is actual saturated refrigerant temperature, the reference data is a reference saturated refrigerant temperature, and wherein the predetermined range for the condenser fault alert is between about 6 degrees F. to about 12 degrees F. above the calculated reference saturated refrigerant temperature.

26. The method of claim 19, further comprised of the step of shutting the system down if the gathered data does not fall within a predetermined minimum threshold based on the corresponding reference data.