Energy efficient CRAC unit operation using heat transfer levels

• US 7,010,392 B2
• Filed: 05/26/2004
• Issued: 03/07/2006
• Est. Priority Date: 05/26/2004
• Status: Expired

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Bash, Cullen E., Sharma, Ratnesh K., Beitelmal, Abdlmonem
• Primary Examiner(s): Gandhi, Jayprakash N.
• Assistant Examiner(s): KASENGE, CHARLES R
• Application Number:
  US10/853,522
• Publication Number:
  US 20050278069A1
• Time in Patent Office: 650 Days
• Field of Search: 700/276, 700/291, 700/293, 700/299, 700/300, 621/73, 621/77, 621/80, 454/239, 705/400
• US Class Current: 700/276
• 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 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 11/83 by controlling the supply of heat-exchange fluids to heat-exchangers
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: H05K 7/207 Thermal management, e.g. cabinet temperature control

Abstract

A method for controlling one or more computer room air conditioning (CRAC) units for energy efficient operation, in which, the temperature of the air returned (Trat) into the one or more CRAC units and the temperature of the air supplied (Tsat) by the one or more CRAC units is detected. The caloric heat transfer level (Q) is calculated based upon the Trat and the Tsat and it is determined whether the Q is within a predetermined setpoint caloric heat transfer range. In addition, at least one operation of the one or more CRAC units is reduced in response to the Q being within the predetermined setpoint caloric heat transfer range to thereby increase the efficiencies of the one or more CRAC units.

Claims

1. A method for controlling one or more computer room air conditioning (CRAC) units for energy efficient operation, wherein said CRAC units comprise a cooling system and a blower, said one or more CRAC units being configured to receive return air, and wherein said cooling system comprises at least one of a refrigerant and a coolant configured to cool the return air, said method comprising:

detecting a power consumption of the cooling system;

detecting a power consumption of the blower;

calculating costs associated with the cooling system power consumption and the blower power consumption;

comparing the costs associated with increasing the temperature of the at least one of the refrigerant and the coolant and the costs associated with decreasing the volume flow rate of air delivered by the blower; and

reducing at least one operation of the one or more CRAC units in response to the compared costs.

2. The method according to claim 1, wherein the step of reducing at least one operation of the one or more CRAC units comprises increasing the temperature of the at least one of the refrigerant and the coolant in response to the costs associated with increasing the temperature of the at least one of the refrigerant and the coolant being below the costs associated with decreasing the volume flow rate of air delivered by the blower;

and

wherein the step of reducing at least one operation of the one or more CRAC units comprises decreasing the volume flow rate of air delivered by the blower in response to the costs associated with decreasing the volume flow rate of air delivered by the blower being below the costs associated with increasing the temperature of the at least one of the refrigerant and the coolant.

3. The method according to claim 1, wherein the cooling system includes at least one of a refrigerant and a coolant configured to cool the return air, and wherein the step of calculating costs comprises calculating costs associated with increasing the temperature of at least one of the refrigerant and the coolant and decreasing a volume flow rate of air delivered by the blower, the method further comprising:

determining a level of increased temperature of the at least one of the refrigerant and the coolant and a level of decreased volume flow rate of air delivered by the blower that relates to minimized costs associated with increasing the temperature of the at least one of the refrigerant and the coolant and with decreasing the volume flow rate of air delivered by the blower; and

wherein the step of reducing at least one operation of the one or more CRAC units comprises implementing the determined level of increased temperature of the at least one of the refrigerant and the coolant and the determined level of the decreased volume flow rate of the air delivered by the blower.

4. The method according to claim 1, wherein the cooling system comprises at least one of a variable capacity compressor and a constant capacity compressor with a variable frequency drive (VFD), and wherein the step of reducing at least one operation of the one or more CRAC units comprises reducing the speed of the at least one of the variable capacity compressor and the constant capacity compressor with the VFD.

5. The method according to claim 1, wherein the cooling system comprises a three-way valve located upstream of a cooling coil, said cooling system further comprising a refrigeration circuit configured to cool a coolant for delivery into the cooling coil, said three-way valve being configured to control the temperature of the coolant contained in the cooling coil by controlling coolant delivery into the cooling coil, wherein the step of reducing a least one operation of the one or more CRAC units comprises reducing the coolant delivery into the cooling coil to thereby reduce the energy consumption of the refrigeration circuit in cooling the coolant.

6. The method according to claim 1, wherein the cooling system comprises a two-way valve located upstream of a cooling coil, said cooling system further comprising a refrigeration circuit configured to cool a coolant for delivery into the cooling coil, said two-way valve being configured to control the temperature of the coolant contained in the cooling coil by controlling coolant delivery into the cooling coil, wherein the step of reducing at least one operation of the one or more CRAC units comprises reducing the coolant delivery into the cooling coil to thereby reduce the energy consumption of the refrigeration circuit in cooling the coolant.

7. The method according to claim 1, wherein the blower comprises a variable frequency drive (VFD), and wherein the step of reducing at least one operation of the one or more CRAC units comprises operating the VFD to reduce the speed of the blower to thereby reduce to power consumption of the blower.

14. The method according to claim 1, wherein the one or more CRAC units comprise a plurality of CRAC units, and wherein one or more of the plurality of CRAC units are configured with at least one of a three-way valve and a two-way valve to control coolant delivery into a cooling coil of the one or more of the CRAC units, the method further comprising:

operating the plurality of CRAC units to enable the one or wore of the plurality of CRAC units to maintain the at least one of the three-way valve and the two-way valve substantially at 100% open positions to thereby reduce energy usage by the one or more of the plurality of CRAC units.

8. A method for controlling one or more computer room air conditioning (CRAC) units for energy efficient operation, wherein said CRAC units comprise a cooling system and a blower, said one or more CRAC units being configured to receive return air, and wherein said cooling system comprises at least one of a refrigerant and a coolant configured to cool the return air, said method comprising:

detecting the temperature of the air returned (Trat) into the one or more CRAC units;

determining whether the Trat is below a minimum setpoint temperature level-in

calculating costs associated with decreasing the temperature of at least one of the refrigerant and the coolant;

calculating costs associated with increasing a volume flow rate of air delivered by the blower;

comparing the costs associated with decreasing the temperature of at least one of the refrigerant and the coolant and the costs associated with increasing the volume flow rate of air delivered by the blower; and

operating the one or more CRAC units to at least one of decrease a temperature of at least one of a refrigerant and a coolant and increase a volume flow rate of cooling fluid delivered by a blower of the one or more CRAC units in response to the Trat being above the minimum setpoint temperature level.

9. The method according to claim 8 wherein the step of operating the one or more CRAC units comprises decreasing the temperature of the at least one of the refrigerant and the coolant in response to the costs associated with decreasing the temperature of the at least one of the refrigerant and the coolant being below the costs associated with increasing the volume flow rate affair delivered by the blower;

end wherein the step of operating the one or more CRAC units comprises increasing the volume flow rate of air delivered by the blower in response to the casts associated with increasing the volume flow rate of air delivered by the blower being below the costs associated with decreasing the temperature of the at least one of the refrigerant and the coolant.

10. The method according to claim 8 wherein the step of calculating costs comprises calculating costs associated with decreasing the temperature of at least one of the refrigerant and the coolant and increasing a volume flow rate of air delivered by the blower, the method further comprising:

determining a level of decreased temperature of the at least one of the refrigerant and the coolant and a level of increased volume flow rate of air delivered by the blower that relates to minimized costs associated with decreasing the temperature of the at least one of the refrigerant and the coolant and with increasing the volume flow rate of air delivered by the blower; and

wherein the step of operating the one or more CRAC units comprises implementing the determined level of decreased temperature of the at least one of the refrigerant and the coolant and the determined level of the increased volume flow rate of the air delivered by the blower.

11. The method according to claim 8 further comprising

causing the one or more CRAC units to enter into a reduced power mode in response to the Trat being below the minimum setpoint temperature level.

12. The method according to claim 11 further comprising:

detecting the Trat while the one or more CRAC units are in the reduced power mode; and

causing the one or more CRAC units to exit from the reduced power mode in response to the Trat exceeding a predefined temperature level.

13. The method according to claim 11 wherein the one or more CRAC units comprise a plurality of CRAC units, and wherein the plurality of CRAC units are configured to communicate with each other, the method further comprising:

signaling a CRAC unit to exit from the reduced power mode in response to a Trat of another CRAC unit exceeding a predefined level.

15. A computer room air conditioning (CRAC) unit comprising:

a return air temperature sensor; and

a controller configured to compare the temperature of the return air (Trat) with a predetermined setpoint temperature range to determine whether the Trat is below a minimum setpoint temperature level in response to the Trat being outside of the predetermined setpoint temperature range, wherein the controller is further configured to reduce at least one operation of the CRAC unit by at least one of decreasing a temperature of cooling fluid delivered by the CRAC unit and increasing a volume flow rate of c un fluid delivered by the CRAC unit in response to the Trat being above the minimum setpoint temperature level and wherein the controller is configured to cause the CRAC unit to enter into a reduced power mode in response to the Trat being below the minimum setpoint temperature level and cause the CRAC unit to withdraw the CRAC unit from the reduced power mode in response to the detected Trat exceeding a predefined temperature level.

16. The CRAC unit of claim 15, further comprising:

a cooling system;

a blower; and

a power meter configured to detect a power consumption of the cooling system and the blower,

wherein the controller is configured to calculate costs associated with the power consumptions of the cooling system and the blower and to base the reduction of the at least one operation of the CRAC unit on the costs associated with operating the cooling system and the blower.

17. The CRAC unit according to claim 16 wherein the cooling system comprises at least one of a variable capacity compressor and a constant capacity compressor with a variable frequency drive (VFD), and wherein the controller is operable to reduce operations of the at least one of the variable capacity compressor and the constant capacity compressor with a VFD in response to the temperature of the return air being within the predetermined setpoint temperature range.

18. The CRAC unit according to claim 16 wherein the cooling system comprises a three-way valve located upstream of a cooling coil, said cooling system further comprising a refrigeration circuit configured to cool a coolant for delivery into the cooling coil, said three-way valve being configured to control the temperature of the coolant contained in the cooling coil by controlling coolant delivery into the cooling coil, wherein the controller is configured to operate the three-way valve to reduce the coolant delivery into the cooling coil in response to the return air being within the predetermined setpoint temperature range.

19. The CRAC unit according to claim 16 wherein the cooling system comprises a two-way valve located upstream of a cooling coil, said cooling system further comprising a refrigeration circuit configured to cool a coolant for delivery into the cooling coil, said two-way valve being configured to control the temperature of the coolant contained in the cooling coil by controlling coolant delivery into the cooling coil, wherein the controller is configured to operate the two-way valve to reduce the coolant delivery into the cooling coil in response to the return air being within the predetermined setpoint temperature range.

20. The CRAC unit according to claim 16 wherein the blower comprises a variable frequency drive (VFD), and wherein the controller is configured to operate the VFD to reduce the speed of the blower in response to the return air being within the predetermined setpoint temperature range.

21. A system for controlling a computer room air conditioning (CRAC) unit, said system comprising:

means for detecting a temperature of air returned (Trat) into the CRAC unit;

means for determining whether the Trat is within a predetermined setpoint temperature range, said means for determining also including means for reducing at least one operation of the CRAC unit in response to the Trat being within the predetermined setpoint temperature range; and

means for causing CRAC unit to enter into a reduced power mode in response to the Trat being below the minimum setpoint temperature level, said means for detecting Trat being configured to detect the Trat while the CRAC unit is in the reduced power mode, and wherein the means for determining is further configured to cause the CRAC unit to exit from the reduced power mode in response to the Trat exceeding a predefined temperature level.

22. The system according to claim 21 further comprising:

means for varying a temperature of cooling fluid supplied by the CRAC unit;

means for varying a volume flow rate of cooling fluid supplied by the CRAC unit; and

means for detecting a power consumption of the means for varying temperature and the means for varying volume flow rate, wherein the means for determining comprises means for calculating costs associated with the power consumptions of the means for varying temperature and the means for varying volume flow rate.

23. The system according to claim 22 wherein the means for determining further comprises means for comparing the Trat to a minimum setpoint temperature level, said means for determining further comprising means for operating at least one of the means for varying temperature and the means far varying volume flow rate to operate at reduced energy consumption levels in response to the Trat being below the minimum setpoint temperature level.

24. A computer readable storage medium on which is embedded one or more computer programs, said one or more computer programs implementing a method for controlling a computer room air conditioning (CRAC) unit for energy efficient operation, said CRAC unit being configured to receive return air, said one or more computer programs comprising a set of instructions for:

detecting the temperature of the air returned (Trat) into the CRAC unit;

determining whether the Trat is within a predetermined setpoint temperature range;

determining whether the Trat is below a minimum setpoint temperature level in response to the Trat being outside of the predetermined setpoint temperature range;

causing the CRAC unit to enter into a reduced power mode in response to the Trat being below the minimum setpoint temperature level;

detecting the Trat while the CRAC unit is in the reduced power mode; and

causing the CRAC unit to exit from the reduced power mode in response to the Trat exceeding a predefined temperature level.

25. The computer readable storage medium according to claim 24, said one or more computer programs further comprising a set of instructions for:

operating the CRAC unit to at least one of decrease a temperature of cooling fluid delivered by the CRAC unit and increase a volume flow rate of cooling fluid delivered by the CRAC unit in response to the Trat being above the minimum setpoint temperature level.