Air conditioning unit control to reduce moisture varying operations

• US 7,155,318 B2
• Filed: 11/05/2004
• Issued: 12/26/2006
• Est. Priority Date: 11/05/2004
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Bash, Cullen E., Sharma, Ratnesh K., Patel, Chandrakant D.
• Primary Examiner(s): PATEL, RAMESH B
• Application Number:
  US10/981,487
• Publication Number:
  US 20060100744A1
• Time in Patent Office: 781 Days
• Field of Search: 700/276, 700/277, 700/278, 62/92, 62/93, 624/27, 621/766, 454/179, 239/34, 165/210, 165/229, 165/104.19, 165/900
• US Class Current: 700/276
• CPC Class Codes: F24F 11/0008 for air-humidification F24F11/30 takes precedence
• CPC Class Codes: H05K 5/0212 Condensation eliminators
• CPC Class Codes: H05K 5/0213 Venting apertures; Constructional details thereof
• CPC Class Codes: H05K 7/20745 within rooms for removing heat from cabinets, e.g. by air conditioning device
• CPC Class Codes: H05K 7/20836 Thermal management, e.g. server temperature control
• CPC Class Codes: Y10S 165/90 Cooling towers

Abstract

In a method of operating an air conditioning unit to reduce moisture varying operations, psychrometric chart data is accessed. In addition, a constraint is set on the relationship between the temperature of air supplied by the air conditioning unit and the relative humidity of the air supplied based upon information contained in the psychrometric chart data. The air conditioning unit is controlled based upon the constraint to thereby reduce moisture varying operations of the air conditioning unit.

Claims

1. A method of operating an air conditioning unit to reduce moisture varying operations, said method comprising:

accessing psychrometric chart data;

setting a specific humidity level for the air conditioning unit;

detecting the temperature of air supplied by the air conditioning unit;

determining a relative humidity act point based upon a relationship between the temperature of the air and the set specific humidity level from information contained in the psychrometric chart data, wherein the relative humidity set point comprises a threshold at which a humidification device of the air conditioning unit is activated; and

varying the relative humidity set point of the air conditioning unit to maintain a substantially constant level of specific humidity at the set specific humidity level to thereby reduce moisture varying operations of the humidification device.

2. The method according to claim 1, further comprising:

determining whether the relative humidity set point is outside of a predetermined range; and

setting the relative humidity set point in response to the relative humidity set point being inside of the predetermined range to substantially prevent the air conditioning unit from varying moisture content.

3. The method according to claim 2, wherein the predetermined range comprises a maximum relative humidity set point and a minimum relative humidity set point, said method further comprising:

decreasing the moisture content in the supplied air in response to the relative humidity set point exceeding the maximum relative humidity set point; and

increasing the moisture content in the supplied air in response to the relative humidity set point falling below the minimum relative humidity set point.

4. The method according to claim 2, wherein the predetermined range is between around 20% to 80% relative humidity.

5. The method according to claim 1, wherein the predetermined range is defined according to safe operating conditions for electronic components positioned to be cooled by the air conditioning unit.

6. A method of operating an air conditioning unit to reduce moisture varying operations, said method comprising:

accessing psychrometric chart data;

defining respective relative humidity value bands from the psychrometric chart data for a plurality of supply air temperatures based upon relative humidity ranges determined to provide suitable relative humidity levels for the respective plurality of supply air temperatures;

detecting the temperature of air supplied by the air conditioning unit;

selecting the relative humidity value band associated with the temperature of the air supplied;

detecting the relative humidity of the air supplied;

determining whether the detected relative humidity is within the selected relative humidity value band; and

activating a humidification device of the air conditioning unit in response to the detected relative humidity falling outside of the selected relative humidity value band.

7. The method according to claim 6, further comprising:

determining whether the detected relative humidity exceeds a predetermined maximum allowable relative humidity in response to the detected relative humidity falling outside of the selected relative humidity band; and

wherein to predetermined maximum allowable relative humidity comprises an upper limit of the relative humidity band.

8. The method according to claim 7, wherein activating the humidification device further comprises:

decreasing to moisture content in the supplied air in response to the detected relative humidity exceeding the predetermined maximum allowable relative humidity; and

increasing the moisture content in the supplied air in response to the detected relative humidity falling below a predetermined minimum allowable relative humidity, wherein the predetermined minimum allowable relative humidity comprises a lower limit of the relative humidity value band.

9. A method of operating an air conditioning unit to reduce moisture varying operations, said method comprising:

accessing psychrometric chart data;

determining a supply air temperature set point;

determining a relative humidity set point, said relative humidity set point comprising a threshold at which a humidification device of the air conditioning unit is activated;

detecting the temperature of the intake air of the air conditioning unit;

calculating the energy consumption required to achieve the supply air temperature set point and the relative humidity set point based upon the detected intake air temperature;

determining whether the required energy consumption exceeds a predetermined threshold, said predetermined threshold comprising a minimum amount of energy required to change the temperature of airflow supplied by the air conditioning unit without causing the humidification device to activate; and

determining a comfort region based upon the psychrometric chart data around the relative humidity set point in response to the required energy consumption exceeding the predetermined threshold.

10. The method according to claim 9, further comprising:

determining whether a first number of iterations exceeds a first predetermined maximum number of iterations in response to the required energy consumption exceeding the predetermined threshold.

wherein determining a comfort region further comprises determining a comfort region around the relative humidity set point from the psychrometric chart data in response to the first number of iterations falling below the first predetermined maximum number of iterations; and

recalculating the relative humidity set point such that the recalculated relative humidity set point is within the comfort region.

11. The method according to claim 10, further comprising:

recalculating the energy consumption required to achieve the recalculated relative humidity set point; and

determining whether the recalculated required energy consumption exceeds the predetermined threshold.

12. The method according to claim 11, further comprising:

determining whether a second number of iterations exceeds a second predetermined maximum number of iterations in response to the first number of iterations exceeding the first predetermined maximum number of iterations; and

activating an alarm in response to the second number of iterations falling below the second predetermined maximum number of iterations.

13. The method according to claim 12, further comprising:

raising a threshold cooling load of the air conditioning unit in response to the second number of iterations exceeding the second predetermined number of iterations.

14. The method according to claim 12, further comprising:

recalculating the supply air temperature set point;

recalculating the energy consumption required to achieve the recalculated supply air temperature set point; and

determining whether the recalculated required energy consumption exceeds the predetermined threshold.

15. A system for operating an air conditioning unit, said system comprising:

a temperature sensor configured to detect temperature around the air conditioning unit;

a controller configured to control a humidification device for varying moisture content in the air supplied by to air conditioning unit;

a memory accessible by the controller, said memory storing psychrometric chart data;

wherein the controller is configured to define a specific humidity level for the air conditioning unit and to determine a relative humidity set point based upon a relationship between the temperature of the air and the predefined specific humidity level from information contained in the psychrometric chart data, wherein the relative humidity set point comprises a threshold at which the humidification device is activated; and

wherein the controller is further configured to vary the relative humidity set point of the air conditioning device at the predefined specific humidity level to thereby reduce moisture varying operations of the humidification device.

16. The system according to claim 15, wherein the controller is further configured to vary the relative humidity set point to substantially prevent die humidification device from operating when the relative humidity set point is within a predetermined range comprised of a minimum relative humidity set point and a maximum relative humidity set point along the substantially constant level of the predefined specific humidity level.

17. The system according to claim 15, wherein the controller includes a supply air temperature control module and a relative humidity control module, wherein the relative humidity control module is configured to control the moisture varying device.

18. The system according to claim 15, wherein the controller comprises a computing device configured to control a plurality of air conditioning units.

19. A system for operating an air conditioning unit, said system comprising:

a temperature sensor positioned to detect the temperature of air supplied by the air conditioning unit;

a sensor for detecting relative humidity in the air supplied by the air conditioning unit;

a controller configured to control a humidification device for varying moisture content in the air supplied by the air conditioning unit;

a memory accessible by the controller, said memory storing psychrometric chart data;

wherein the controller is configured to define relative humidity value bands from the psychrometric chart data for a plurality of supply air temperatures based upon relative humidity ranges determined to provide suitable relative humidity levels for the respective plurality of supply air temperatures and to select the relative humidity value band associated with the air supply temperature detected by the temperature sensor, and

said controller being further configured to determine whether the detected relative humidity is within the selected humidity value band, and wherein the controller is configured to operate the moisture varying device bused upon the detected relative humidity falling outside of the selected relative humidity value band.

20. The system according to claim 19, wherein the controller is further configured to determine whether the detected relative humidity exceeds a predetermined maximum allowable relative humidity in response to the detected relative humidity falling outside of the selected relative humidity band, wherein the predetermined maximum allowable relative humidity comprises an upper limit of the relative humidity band.

21. The system according to claim 20, wherein the controller is further configured to decrease the moisture content in the supplied air in response to the detected relative humidity exceeding the predetermined maximum allowable relative humidity and to increase the moisture content in the supplied air in response to the detected relative humidity falling below a predetermined minimum allowable relative humidity, wherein the predetermined minimum allowable relative humidity comprises a lower limit of the relative humidity value band.

22. A system for operating an air conditioning unit, said system comprising:

a temperature sensor configured to detect temperature supplied into the air conditioning unit;

a controller configured to control a humidification device for varying moisture content in the air supplied by the air conditioning unit;

a memory accessible by the controller, said memory storing psychrometric chart data;

wherein the controller is configured to determine a supply air temperature set point and a relative humidity set point, said relative humidity set point comprising a threshold at which a humidification device of the air conditioning unit is activated;

wherein the controller is configured to calculate the energy consumption required to achieve the supply air temperature set point and the relative humidity set point based upon the detected intake air temperature, said controller being further configured to determine whether the required energy consumption exceeds a predetermined threshold, said predetermined threshold comprising a minimum amount of energy required to change the temperature of airflow supplied by the air conditioning unit without causing the humidification device to activate, and to determine a comfort region based upon the psychrometric chart data round the relative humidity set point in response to the required energy consumption exceeding the predetermined threshold.

23. The system according to claim 22, wherein the controller is further configured to recalculate the relative humidity set point such that the recalculated relative humidity set point is within the comfort region in response to the required energy consumption exceeding the predetermined threshold.

24. The system according to claim 23, wherein the controller is further configured to recalculate the energy consumption required to achieve the recalculated relative humidity set point, and to determine whether the recalculated required energy consumption exceeds the predetermined threshold.

25. The system according to claim 24, wherein the controller is configured to activate an alarm in response to the required energy consumption exceeding the predetermined threshold.

26. The system according to claim 25, wherein the controller is further configured to recalculate the supply air temperature set point, to recalculate the energy consumption required to achieve the recalculated supply air temperature, and to determine whether the recalculated energy consumption exceeds the predetermined threshold.

27. The system according to claim 26, wherein the controller is configured to raise a threshold cooling load of the air conditioning unit in response to the recalculated energy consumption exceeding the predetermined threshold.

28. A computer readable storage medium on which is embedded one or more computer programs, said one or more computer programs implementing a method of operating an air conditioning unit to substantially reduce moisture varying operations, said one or more computer programs comprising a set of instructions for:

accessing psychrometric chart data;

setting a specific humidity level for the air conditioning unit;

detecting the temperature of air supplied by the air conditioning unit;

determining a relative humidity set point based upon a relationship between the temperature of the air and the set specific humidity level from information contained in the psychrometric chart data, wherein the relative humidity set point comprises a threshold at which a humidification device of the air conditioning unit is activated; and

varying the relative humidity set point of the air conditioning unit to maintain a substantially constant level of specific humidity at the set specific humidity level to thereby reduce moisture varying operations of the humidification device.

29. The computer readable storage medium according to claim 28, said one or more computer programs further comprising a set of instructions for:

decreasing the moisture content in the supplied air in response to the relative humidity set point exceeding a maximum relative humidity set point; and

increasing the moisture content in the supplied air in response to the relative humidity set point falling below a minimum relative humidity set point.