Anti-condensation control system

• US 7,340,907 B2
• Filed: 05/09/2005
• Issued: 03/11/2008
• Est. Priority Date: 05/10/2004
• Status: Expired due to Fees

• Current Assignee: Emerson Climate Technologies Retail Solutions Incorporated (Emerson Electric Company)
• Original Assignee: Computer Process Controls Incorporated (Emerson Electric Company)
• Inventors: Vogh, Richard P. III
• Primary Examiner(s): Jiang; Chen Wen
• Application Number:
  US11/124,909
• Publication Number:
  US 20050268627A1
• Time in Patent Office: 1,037 Days
• Field of Search: 621/50, 62/93, 62/80, 621/40, 621/56, 622/65, 236/44.R, 236/44.A, 165/222, 165/223, 165/230
• US Class Current: 62/150
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 2013/221 to avoid the formation of condensate, e.g. dew
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: F25D 21/04 Preventing the formation of frost or condensate

Abstract

An anti-condensation control apparatus for a refrigeration device generally includes a sensor module and a control module. The control module receives an input from the sensor module and compares the input to a set point. The control module generates an output indicative of a difference between the input and the set point and updates the output based on the input from the sensor module. A heater modulator controls a heater based on the output from the control module to maintain a temperature of the outer surface of a refrigerated device such that relative humidity adjacent the sensor module is substantially between 90-95 percent relative humidity, or slightly above dew point.

Claims

1. An anti-condensation control apparatus for a refrigeration device comprising:

a sensor module;

a control module receiving an input from said sensor module and operable to compare said input to a set point and generate an output indicative of a difference between said input and said set point, said control module continuously updating said output based on said input from said sensor module; and

a heater modulator operable to control a heater based on said output to maintain air adjacent said sensor module to a temperature such that relative humidity at said sensor module is generally between 90-95 percent.

2. The apparatus of claim 1, wherein said control module uses closed-loop control to control said heater.

3. The apparatus of claim 1, wherein said sensor module includes a sensor mounted to a control surface selected from the group comprising:

a glass pane, a casing, a frame, a rail, or a wall of the refrigeration device.

4. The apparatus of claim 3, wherein said sensor is fixedly attached to said control surface.

5. The apparatus of claim 3, wherein said control surface is disposed within said casing, frame, rail, or wall of the refrigeration device.

6. The apparatus of claim 5, wherein said casing, frame, rail, or wall includes an air passage to allow said adjacent air to interact with said sensor.

7. The apparatus of claim 5, wherein said sensor includes at least one sensor module baffle protecting said sensor from debris.

8. The apparatus of claim 1, wherein said sensor module is disposed within a tube fixedly attaching said sensor to the refrigeration device.

9. The apparatus of claim 8, wherein said tube is generally open at one end.

10. The apparatus of claim 8, wherein said tube includes a baffle protecting said sensor from debris.

11. The apparatus of claim 8, wherein said tube includes at least one air passage to allow said adjacent air to interact with said sensor.

12. The apparatus of claim 1, wherein said sensor module includes a relative humidity sensor.

13. The apparatus of claim 1, wherein said control module includes a controller and at least one of an adder-subtractor and a limiter.

14. The apparatus of claim 13, wherein said controller comprises a proportional integral derivative controller.

15. An anti-condensation control apparatus for a bank of refrigeration devices comprising:

a sensor module positioned on a control surface of at least one of the refrigeration devices;

a control module receiving an input from said sensor module and operable to compare said input to a set point and generate an output indicative of a difference between said input and said set point, said control module continuously updating said output based on said input from said sensor module; and

a heater modulator operable to control a heater of each of the refrigeration devices based on said output to maintain a temperature of air adjacent a control surface of each of the refrigeration devices and the sensor module to a temperature such that relative humidity at the sensor module is generally between 90-95 percent.

16. The apparatus of claim 15, wherein said control module uses closed-loop control to control said heater.

17. The apparatus of claim 15, wherein said sensor module is mounted to said control surface and said control surface is selected from the group comprising:

a glass pane, a casing, a frame, a rail, or a wall of the refrigeration device.

18. The apparatus of claim 15, wherein said sensor module includes a relative humidity sensor.

19. A method of controlling condensation on a refrigeration device, the method comprising;

sensing a condition of air adjacent a sensor associated with the refrigeration device;

comparing said input to a set point;

outputting an error based on said comparison;

processing said error to determine an output between zero and one hundred percent;

modifying said output between a percent minimum and percent maximum; and

heating a surface of the refrigeration device adjacent said sensor to maintain a temperature of said surface such that the relative humidity at said sensor is approximately 90-95 percent.

20. The method of claim 19, wherein said sensing a condition of air includes sensing a relative humidity of said air adjacent said sensor.

21. The method of claim 20, further comprising sensing a temperature of said surface.

22. A method of controlling condensation on a refrigeration device, the method comprising:

sensing a condition of air adjacent a sensor associated with the refrigeration device;

comparing said input to a set point;

outputting an error based on said comparison;

processing said error to determine an output between zero and one hundred percent;

modifying said output between a percent minimum and percent maximum; and

heating a surface of the refrigeration device to maintain a temperature of said air adjacent said sensor such that the relative humidity of said sensor is approximately 90-95 percent.

23. The method of claim 22, wherein said modifying includes use of closed-loop control.

24. The method of claim 22, wherein said sensing a condition of air includes sensing a dew point of said air adjacent said sensor.