Method and apparatus for controlling evaporator and condenser fans in a refrigeration system

• US 20010054293A1
• Filed: 04/10/2001
• Published: 12/27/2001
• Est. Priority Date: 04/10/2000
• Status: Active Grant

• Current Assignee: Thermo King Corporation (Trane Technologies plc)
• Original Assignee: Thermo King Corporation (Trane Technologies plc)
• Inventors: Gustafson, Alan, Crombie, Dermott, Freese, Mark
• Granted Patent: US 6,560,980 B2
• Time in Patent Office: Days
• US Class Current: 62/183
• CPC Class Codes: F25B 2600/111 of condenser fans
• CPC Class Codes: F25B 2600/112 of evaporator fans
• CPC Class Codes: F25B 2700/15 Power, e.g. by voltage or current
• CPC Class Codes: F25B 2700/2116 of a condenser
• CPC Class Codes: F25B 2700/21174 of the refrigerant at the inlet of the evaporator
• CPC Class Codes: F25B 2700/21175 of the refrigerant at the outlet of the evaporator
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: F25B 49/027 Condenser control arrangements
• CPC Class Codes: F25D 17/06 by forced circulation
• CPC Class Codes: F25D 29/003 for movable devices
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A method and apparatus for controlling evaporator and condenser fans in a refrigeration system. The apparatus is a refrigeration system including a refrigerant circuit defined by a compressor, a condenser, a throttling device, and an evaporator. The apparatus includes an evaporator fan and a condenser fan. The apparatus also includes a controller coupled to the fans. The controller includes a variable frequency drive unit. For the method of the invention, the speed of the fans is controlled by the controller.

Claims

1. A refrigeration system comprising:

a refrigerant circuit defined by a compressor, a condenser, a throttling device, and an evaporator;

at least one evaporator fan; and

a controller coupled to the at least one evaporator fan, the controller including a variable frequency drive unit for providing variable frequency power to the at least one evaporator fan.

2. The refrigeration system of

claim 1

wherein the at least one evaporator fan is a continuously-variable speed fan.

3. The refrigeration system of

claim 1

and further comprising at least one sensor coupled to the refrigerant circuit for sensing a system parameter.

4. The refrigeration system of

claim 3

wherein the at least one sensor includes a first sensor for sensing the temperature of air flowing into the evaporator and a second sensor for sensing the temperature of air flowing out of the evaporator, and wherein the controller adjusts an evaporator fan speed based on the sensed temperatures.

5. The refrigeration system of

claim 4

wherein the controller includes an alternating current power source coupled to the variable frequency drive unit.

6. The refrigeration system of

claim 5

wherein the controller includes a microprocessor coupled to the at least one sensor and the variable frequency drive unit.

7. The refrigeration system of

claim 6

and further comprising at least one condenser fan.

8. The refrigeration system of

claim 7

wherein the condenser fan is a continuously-variable speed fan.

9. The refrigeration system of

claim 7

wherein the at least one sensor includes a third sensor coupled to the condenser for sensing the temperature of the condenser, and wherein the controller adjusts a condenser fan speed based on the sensed temperature.

10. The refrigeration system of

claim 7

wherein the controller includes a first switch, a first input to the first switch coupled to the alternating current power source, a second input to the first switch coupled to the variable frequency drive unit, and an output from the first switch coupled to a first input of a second switch, a second input to the second switch coupled to a ground, and an output from the second switch coupled to the at least one condenser fan.

11. The refrigeration system of

claim 10

wherein the first switch and the second switch are coupled to the microprocessor.

12. The refrigeration system of

claim 11

wherein the microprocessor controls the first switch and the second switch in order to provide power to the at least one condenser fan in the form of a one of alternating current power, alternating current power cycled with variable frequency drive power, and variable frequency drive power cycled with no power.

13. A refrigeration system comprising:

a refrigerant circuit defined by a compressor, a condenser, a throttling device, and an evaporator;

at least one condenser fan; and

a controller coupled to the sensor and the at least one condenser fan, the controller including a variable frequency drive unit for providing variable frequency power to the at least one condenser fan.

14. The refrigeration system of

claim 13

wherein the at least one condenser fan is a continuously-variable speed fan.

15. The refrigeration system of

claim 13

and further comprising at least one sensor coupled to the refrigerant circuit for sensing a system parameter.

16. The refrigeration system of

claim 15

wherein the at least one sensor includes a first sensor coupled to the at least one condenser for sensing the temperature of the condenser, and wherein the controller adjusts a condenser fan speed based on the sensed temperature.

17. The refrigeration system of

claim 16

wherein the controller includes an alternating current power source coupled to the variable frequency drive unit.

18. The refrigeration system of

claim 17

wherein the controller includes a microprocessor coupled to the at least one sensor and the variable frequency drive unit.

19. The refrigeration system of

claim 18

wherein the controller includes a first switch, a first input to the first switch coupled to the alternating current power source, a second input to the first switch coupled to the variable frequency drive unit, and an output from the first switch coupled to a first input of a second switch, a second input to the second switch coupled to a ground, and an output from the second switch coupled to the at least one condenser fan.

20. The refrigeration system of

claim 19

wherein the microprocessor controls the first switch and the second switch in order to provide power to the at least one condenser fan in the form of a one of alternating current power, alternating current power cycled with variable frequency drive power, and variable frequency drive power cycled with no power.

21. A method of controlling the speed of at least one evaporator fan in a refrigeration system, the refrigeration system including a compressor, a condenser, a throttling device, and an evaporator, the method comprising:

providing a desired temperature differential for a conditioned space;

measuring temperature at the inlet to the evaporator;

measuring temperature at the outlet to the evaporator;

calculating an actual temperature differential; and

adjusting an evaporator fan speed based on the desired temperature differential and the actual temperature differential.

22. The method of

claim 21

wherein adjusting an evaporator fan speed includes adjusting the frequency of the power delivered to the at least one evaporator fan.

23. The method of

claim 21

and further comprising determining whether the actual temperature differential is greater than, less than, or equal to the desired temperature differential.

24. The method of

claim 23

wherein adjusting an evaporator fan speed includes increasing the evaporator fan speed if the actual temperature differential is greater than the desired temperature differential.

25. The method of

claim 23

wherein adjusting an evaporator fan speed includes maintaining the evaporator fan speed if the actual temperature differential is equal to the desired temperature differential.

26. The method of

claim 23

wherein adjusting an evaporator fan speed includes decreasing the evaporator fan speed if the actual temperature differential is less than the desired temperature differential.

27. A method of controlling the speed of at least one condenser fan in a refrigeration system, the refrigeration system including a compressor, a condenser, a throttling device, and an evaporator, the method comprising:

providing a condenser temperature threshold value;

measuring an actual temperature of the condenser; and

adjusting a condenser fan speed based on the condenser temperature threshold value and the actual temperature.

28. The method of

claim 27

wherein adjusting a condenser fan speed includes adjusting the frequency of the power delivered to the at least one condenser fan.

29. The method of

claim 27

wherein adjusting a condenser fan speed includes decreasing the condenser fan speed when the actual temperature is below the condenser temperature threshold value.

30. The method of

claim 29

wherein decreasing the condenser fan speed includes delivering power to the at least one condenser fan by cycling between a variable frequency drive power source and a ground.

31. The method of

claim 27

wherein adjusting a condenser fan speed includes maintaining the condenser fan speed when the actual temperature is equal to the condenser temperature threshold value.

32. The method of

claim 31

wherein maintaining the condenser fan speed includes delivering power to the at least one condenser fan by cycling between an alternating current power source and a variable frequency drive power source.

33. The method of

claim 27

wherein adjusting a condenser fan speed includes increasing the condenser fan speed when the actual temperature is above the condenser temperature threshold value.

34. The method of

claim 33

wherein increasing the condenser fan speed includes delivering power to the at least one condenser fan from an alternating current power source.