Cooling system with evaporators distributed in parallel

• US 6,786,056 B2
• Filed: 12/04/2002
• Issued: 09/07/2004
• Est. Priority Date: 08/02/2002
• Status: Expired due to Fees

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Patel, Chandrakant D., Bash, Cullen E.
• Primary Examiner(s): NORMAN, MARC E
• Application Number:
  US10/309,188
• Publication Number:
  US 20040020224A1
• Time in Patent Office: 643 Days
• Field of Search: 622/284, 622/29, 621/99, 622/03, 621/78, 621/80, 621/86, 622/592, 622/25
• US Class Current: 62/199
• CPC Class Codes: F25B 2600/0253 with variable speed
• CPC Class Codes: F25B 2600/112 of evaporator fans
• CPC Class Codes: F25B 2600/2515 Flow valves
• CPC Class Codes: F25B 2700/2104 of an indoor room or compartment
• CPC Class Codes: F25B 2700/2117 of an evaporator
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: F25B 5/02 arranged in parallel
• CPC Class Codes: H05K 7/20745 within rooms for removing heat from cabinets, e.g. by air conditioning device
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A system and method for cooling a room configured to house a plurality of computer systems. A plurality of evaporator units are arranged in parallel and are configured to receive air from the room and to deliver air to the room. The evaporator units are supplied with refrigerant operable to cool the received air in the evaporator units. The air may be controlled in response to temperatures sensed at one or more locations in the room.

Claims

1. A method for cooling a room configured to house a plurality of computer systems, said method comprising:

providing a plurality of evaporator units distributed in parallel along refrigerant lines and configured to receive air from said room and to deliver air to said room;

supplying said plurality of evaporator units with refrigerant through the refrigerant lines, wherein an evaporator valve is positioned upstream of each of said plurality of evaporator units, wherein said refrigerant is operable to cool said air in said plurality of evaporator units;

sensing temperatures at one or more locations in said room;

controlling the temperature of said air in response to said step of sensing temperatures at said one or more locations;

sensing a superheat temperature of said refrigerant exiting from at least one of said plurality of evaporator units; and

varying the refrigerant supplied to each of said plurality of evaporator units in response to the sensed superheat temperature through operation of said evaporator valves to control the temperature of said air.

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

providing a refrigeration system configured to manipulate the temperature of said refrigerant, wherein said controlling step comprises varying an output of said refrigeration system to control the temperature of said refrigerant.

3. The method according to claim 2, wherein said refrigeration system comprises a refrigeration loop having a variable speed compressor and having at least one expansion valve, wherein the evaporator valves are configured to meter flow of said refrigerant through at least one of said plurality of evaporator units, and wherein said step of controlling the temperature of said refrigerant comprises controlling the operation of said variable speed compressor.

4. The method according to claim 2, wherein said plurality of evaporator units comprises at least one fan configured to effectuate delivery of said air, and wherein said step of controlling at least one of the temperature of said refrigerant and said air comprises varying an output of said fan to control the delivery of air to the room.

5. The method according to claim 4, further comprising:

determining whether said temperatures at said one or more locations in said room are within a predetermined range.

6. The method according to claim 5, further comprising:

determining whether said temperatures are at least one of less than and equal to a minimum set point temperature in response to said temperatures at one or more locations in said room being outside of said predetermined range.

7. The method according to claim 6, wherein said controlling step comprises at least one of the following steps:

decreasing delivery of said air to said room in response to said temperatures at said one or more locations being at least one of less than and equal to said minimum set point temperature; and

increasing delivery of said air to said room in response to said sensed temperatures being above said minimum set point temperature and outside of said predetermined range.

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

sensing temperatures again at one or more locations in said room; and

recording whether said decreasing and said increasing steps had their intended effect.

9. The method according to claim 8, further comprising:

using said recording step to provide input to performing a numerical modeling of temperature distribution and flow characteristics of said air within said room.

10. The method according to claim 5, further comprising:

varying at least one of the amount of said refrigerant and the temperature of said refrigerant in response to the said temperatures at one or more locations in said room being outside of said predetermined range.

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

sensing a saturation temperature of said refrigerant;

increasing the speed of said variable speed compressor in response to said saturation temperature exceeding a saturation temperature set point; and

decreasing the speed of said variable speed compressor in response to said saturation temperature being less than or equal to said predetermined saturation temperature set point.

12. The method according to claim 11,

wherein the step of varying the refrigerant supplied to each of said plurality of evaporator units comprises manipulating said evaporator valve to decrease the flow of refrigerant through said at least one of said plurality of evaporator units in which said superheat temperature of said refrigerant is outside a predetermined superheat temperature range and said superheat temperature of said refrigerant is less than an evaporator superheat temperature set point for said at least one of said plurality of evaporator units;

and

manipulating said evaporator valve to increase the flow of refrigerant through said at least one of said plurality of evaporator units in which said superheat temperature of said refrigerant is outside said predetermined superheat temperature range and said superheat temperature of said refrigerant exceeds or is equal to said evaporator superheat temperature set point for said at least one of said plurality of evaporator units.

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

varying the amount of refrigerant delivered to said at least one of said plurality of evaporator units to maintain said plurality of computer systems at substantially similar temperatures.

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

performing a numerical modeling of temperature distribution and flow characteristics of air within the room; and

manipulating said refrigeration system in response to said numerical modeling.

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

implementing said numerical modeling to correlate at least two of temperature, velocity and pressure of said refrigerant and power draw of said plurality of computer systems to thereby infer a thermal condition throughout said room, wherein said controlling step further comprises manipulating said refrigeration system in response to said thermal condition.

16. The method according to claim 1, wherein said step of sensing temperatures at one or more locations in said room comprises sensing said temperatures with a mobile environmental condition sensing device.

17. The method according to claim 1, wherein said step of sensing temperatures at one or more locations in said room comprises determining said temperatures according to anticipated heat loads of one or more of said plurality of computer systems.

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

manipulating the workload on said plurality of computer systems to optimize energy efficiency in cooling said plurality of computer systems.

19. The method according to claim 1, wherein said step of controlling at least one of the temperature of said refrigerant and said air in response to said temperatures at said one or more locations comprises substantially ceasing air delivery and refrigerant delivery in response to said sensed temperatures being below a predetermined set point temperature.

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

providing a refrigeration system configured to manipulate the temperature of said refrigerant, wherein said step of controlling at least one of the temperature of said refrigerant and said air comprises varying an output of said refrigeration system to control the temperature of said refrigerant.

21. The method according to claim 20, further comprising:

controlling the flow of said refrigerant through said refrigeration system, said refrigeration system having a constant speed compressor and a plurality of valves that meter the flow of said refrigerant respectively through said plurality of evaporator units;

checking a superheat temperature of said refrigerant flowing through said plurality of evaporator units;

manipulating said plurality of valves to decrease the flow of refrigerant respectively through said plurality of evaporator units for each of said plurality of evaporator units in which the respective superheat temperature is less than an evaporator superheat temperature set point; and

sensing a temperature associated with those evaporator units in which said superheat temperature exceeds or is equal to said superheat temperature set point.

22. The method according to claim 21, further comprising:

determining whether said temperature is within a predetermined temperature range; and

determining whether said temperature is above a predetermined temperature for those evaporator units in which said temperature is outside said predetermined rack temperature range.

23. The method according to claim 22, further comprising:

manipulating said plurality of valves to respectively decrease the flow of refrigerant through said plurality of evaporator units for each of those evaporator units in which said temperature is below said predetermined temperature range; and

manipulating said plurality of valves to respectively increase the flow of refrigerant through said plurality of evaporator units for those evaporator units in which said temperature exceeds said predetermined temperature range.

24. The method according to claim 23, further comprising:

manipulating a main valve positioned upstream of said plurality of valves to control the flow of said refrigerant.

25. The method according to claim 24, further comprising:

manipulating said main valve to decrease the flow of said refrigerant therethrough when at least one of said plurality of computer systems has a temperature exceeding said predetermined temperature range; and

manipulating said main valve to increase the flow of refrigerant therethrough when at least one of said plurality of computer systems has a temperature falling below said predetermined temperature range.

26. A system for cooling a room containing a plurality of computer systems, said system comprising:

a plurality of evaporator units distributed in parallel and configured to receive refrigerant through a refrigerant line and to receive air, wherein said air may be cooled through heat transfer with said refrigerant, said plurality of evaporator units having at least one fan configured to cause said air to flow out of said plurality of evaporator units;

an evaporator controller operable to control a supply of said refrigerant to said plurality of evaporator units and operable to control the speed of said at least one fan;

a refrigeration system for cooling said refrigerant;

a refrigeration system controller configured to operate said refrigeration system to vary the temperature of said refrigerant; and

at least one valve configured to meter the flow of said refrigerant through said plurality of evaporator units positioned along said refrigerant line generally upstream of said plurality of evaporator units, wherein said evaporator controller is operable to control the mass flow rate of said refrigerant through said at least one valve.

27. The system according to claim 26, further comprising one or more temperature sensors, wherein said evaporator controller is configured to receive environmental condition information from said one or more temperature sensors.

28. The system according to claim 27, wherein said temperature sensor comprises at least one of a thermocouple and a mobile environmental condition sensing device.

29. The system according to claim 26, wherein said plurality of computer systems are housed in a plurality of racks, and wherein a plurality of heat exchanger units are positioned at various locations in said room to supply air flow to said plurality of racks in a substantially independent manner.

30. The system according to claim 26, further comprising:

a variable speed compressor for controlling the flow of said refrigerant through said refrigerant line; and

a refrigeration system controller configured to control said variable capacity compressor.

31. The system according to claim 30, wherein said at least one valve comprises a plurality of valves corresponding to said plurality of evaporator units and further comprises an expansion valve upstream of said plurality of valves.

32. The system according to claim 30, further comprising a proportional, integral, derivative controller including an input line from a sensor located along said refrigerant line upstream of said plurality of evaporator units and an output line connected to said variable speed compressor, wherein said proportional, integral, derivative controller is capable of sending signals to said variable speed compressor to vary the speed of said refrigerant in response to a saturation temperature measurement of said refrigerant by said sensor.

33. The system according to claim 32, further comprising a plurality of sensors located along said refrigerant line downstream of said plurality of evaporator units, said plurality of sensors being in respective communication with said plurality of valves to thereby respectively meter the amount of said refrigerant entering said plurality of evaporator units.

34. The system according to claim 32, wherein said refrigeration system controller is configured to communicate with said evaporator controller.

35. The system according to claim 34, wherein said communication between said refrigeration system controller and said evaporator controller includes communication of information pertaining to the level of operation of said plurality of evaporator units, and wherein said refrigeration system controller is configured to operate said variable speed compressor in response to said information.

36. The system according to claim 35, wherein said communication comprises at least one of temperature measurements and evaporator unit operations.

37. The system according to claim 26, wherein said plurality of evaporator units is supported from a ceiling of said room.

38. The system according to claim 26, further comprising:

a constant speed compressor within said refrigeration system;

a plurality of refrigerant temperature sensors in communication with said evaporator controller and respectively positioned downstream of said plurality of evaporator units;

a plurality of distributed temperature sensors in communication with said evaporator controller;

a plurality of temperature signal lines connecting said evaporator controller to said plurality of refrigerant temperature sensors and said plurality of distributed temperature sensors;

a plurality of valves positioned generally upstream of and inline with said plurality of evaporator units; and

a plurality of control signal lines connecting said evaporator controller to said plurality of valves;

wherein said evaporator controller is configured to send signals to each of said valves in response to temperature readings measured by at least one of said plurality of refrigerant temperature sensors and said plurality of distributed temperature sensors.

39. The system according to claim 38, wherein said evaporator controller is a programmable logic controller.

40. A system for cooling computer systems housed in one or more racks, said racks being maintained in a room, said system comprising:

means for cooling air including means for receiving refrigerant, wherein the means for receiving refrigerant comprises refrigerant lines configured to deliver refrigerant to a plurality of means for cooling air arranged in a parallel configuration;

means for delivering cooled air to said plurality of computer systems;

means for measuring temperatures at one or more locations in said room;

means for controlling delivery of said cooled air in response to said means for measuring;

means for controlling the temperature of said refrigerant;

means for sensing a superheat temperature of said refrigerant exiting from the means for cooling air; and

means for varying the refrigerant supplied through said refrigerant lines in response to the sensed superheat temperature.

41. The system according to claim 40, further comprising:

means for controlling delivery of said refrigerant through said cooling means.

42. The system according to claim 41, wherein:

said cooling means comprises a plurality of evaporator units distributed in parallel;

said means for controlling delivery of refrigerant comprises means for independently adjusting the flow of refrigerant through at least one of said plurality of evaporator units.

43. A computer readable storage medium on which is embedded one or more computer programs, said one or more computer programs implementing a method of cooling a room configured to house a plurality of computer systems, said one or more computer programs comprising a set of instructions for:

providing a plurality of evaporator units distributed in parallel and configured to receive air from said room and to deliver air to said room;

supplying said plurality of evaporator units with refrigerant, wherein said refrigerant is operable to cool said air in said plurality of evaporator units;

sensing temperatures at one or more locations in said room;

controlling the temperature of said air in response to said temperatures at said one or more locations;

sensing a superheat temperature of said refrigerant exiting from at least one of said plurality of evaporator units; and

varying the refrigerant supplied to each of said plurality of evaporator units in response to the sensed superheat temperature through operation of said evaporator valves to control the temperature of said air.

44. The computer readable storage medium according to claim 43, said one or more computer programs further comprising a set of instructions for:

providing a refrigeration system configured to manipulate the temperature of said refrigerant, wherein said controlling step comprises varying an output of said refrigeration system to control the temperature of said refrigerant.