U.S. patent application number 11/592620 was filed with the patent office on 2008-05-08 for constant temperature crac control algorithm.
This patent application is currently assigned to American Power Conversion Corporation. Invention is credited to Peter Ring Carlsen.
Application Number | 20080104985 11/592620 |
Document ID | / |
Family ID | 39358530 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080104985 |
Kind Code |
A1 |
Carlsen; Peter Ring |
May 8, 2008 |
Constant temperature CRAC control algorithm
Abstract
A method of cooling including providing a fluid flow at a
predetermined temperature, and adjusting at least one cooling
parameter of at least one cooling device to maintain the
predetermined temperature of the fluid flow when a desired mass
flow of the fluid flow changes. A cooling system and further
embodiments are also disclosed.
Inventors: |
Carlsen; Peter Ring;
(Aalborg, DK) |
Correspondence
Address: |
LOWRIE, LANDO & ANASTASI, LLP
ONE MAIN STREET, SUITE 1100
CAMBRIDGE
MA
02142
US
|
Assignee: |
American Power Conversion
Corporation
West Kingston
RI
|
Family ID: |
39358530 |
Appl. No.: |
11/592620 |
Filed: |
November 3, 2006 |
Current U.S.
Class: |
62/228.4 ;
165/104.11 |
Current CPC
Class: |
F24F 11/30 20180101;
F28F 27/00 20130101; H05K 7/20836 20130101 |
Class at
Publication: |
62/228.4 ;
165/104.11 |
International
Class: |
F28D 15/00 20060101
F28D015/00; F25B 49/00 20060101 F25B049/00 |
Claims
1. A method of cooling, the method comprising acts of: A) providing
a fluid flow at a predetermined temperature; and B) adjusting at
least one cooling parameter of at least one cooling device to
maintain the predetermined temperature of the fluid flow when a
desired mass flow of the fluid flow changes.
2. The method of claim 1, wherein maintaining the predetermined
temperature comprises limiting an amount of change in a current
output temperature of the fluid flow.
3. The method of claim 2, wherein the amount of change is limited
to two degrees Fahrenheit per minute and five degrees Fahrenheit
per hour from the predetermined temperature.
4. The method of claim 1, wherein the fluid flow includes an air
flow.
5. The method of claim 1, wherein the at least one cooling
parameter includes at least one speed of a compressor of the at
least one cooling device.
6. The method of claim 5, wherein the at least one speed of the
compressor corresponds to a cooling capacity of the at least one
cooling device.
7. The method of claim 1, further comprising an act of C) changing
the mass flow of the fluid flow, based on at least one
representation of the desired mass flow of the fluid flow.
8. The method of claim 7, further comprising an act of D) receiving
the at least one representation of the desired mass flow of the
fluid flow.
9. The method of claim 7, wherein the act A comprises providing the
fluid flow to at least one piece of electronic equipment.
10. The method of claim 9, wherein the at least one piece of
electronic equipment is stored in at least one rack, and the act A
includes providing the fluid flow to the at least one rack.
11. The method of claim 10, wherein the desired mass flow of the
fluid flow is greater than a second mass flow of the fluid flow
taken in by the at least one rack.
12. The method of claim 10, wherein the desired mass flow of the
fluid flow is at least as great as a second mass flow of the fluid
flow taken in by the at least one rack.
13. The method of claim 10, wherein the act A comprises providing
the fluid flow to a data center room in which the at least one rack
is disposed.
14. The method of claim 7, further comprising an act of D)
measuring at least one physical characteristic on which the at
least one representation of the desired mass flow of the fluid flow
is based.
15. The method of claim 14, wherein the at least one physical
characteristic includes at least one mass flow of the fluid flow
taken in by at least one housing of an object.
16. The method of claim 7, wherein the act C comprises changing at
least one fan speed of the at least one cooling device based, at
least in part, on the at least one representation of the desired
mass flow of the fluid flow.
17. The method of claim 16, wherein the act C comprises changing
the at least one fan speed of the at least one cooling device
based, at least in part, on a mapping of fan speed to output mass
flow of fluid.
18. The method of claim 1, wherein the act B comprises adjusting
the at least one cooling parameter based on at least one stored
value indicating at least one cooling parameter value.
19. The method of claim 18, wherein the at least one stored value
indicates at least one cooling parameter value corresponding to at
least one of a desired cooling capacity of the at least one cooling
device.
20. The method of claim 1, further comprising acts of: C)
monitoring at least one cooling condition; and D) adjusting the at
least one cooling parameter based on a change in the at least one
cooling condition to maintain the desired mass flow of the fluid
flow and the predetermined temperature.
21. The method of claim 20, wherein the at least one cooling
condition includes at least one of a current mass flow of fluid to
current cooling capacity ratio, a pressure loss, a temperature, and
a temperature change.
22. The method of claim 20, wherein the act D includes adjusting
the at least one cooling parameter to avoid spikes in the mass flow
of the fluid and a current output temperature of the fluid.
23. A system for providing a fluid flow at a predetermined
temperature, the system comprising: a cooling element configured to
cool the fluid flow; a fluid moving element configured to provide
the fluid flow; and a controller configured to control at least one
parameter of at least one of the cooling element and the fluid
moving element to maintain the fluid flow at the predetermined
temperature and at a desired mass flow of the fluid.
24. The system of claim 23, wherein to maintain the fluid flow at
the predetermined temperature, the controller is configured to
limit an amount of changing in a current output temperature of the
fluid flow.
25. The system of claim 24, wherein the amount of change is less
than two degrees Fahrenheit per minute and five degrees Fahrenheit
per hour.
26. The system of claim 23, wherein the fluid flow includes an air
flow.
27. The system of claim 23, wherein the cooling element includes at
least one compressor, and the at least one cooling parameter
includes at least one speed of the compressor.
28. The system of claim 23, wherein the controller is configured to
receive at least one indication of the desired mass flow of the
fluid.
29. The system of claim 28, wherein the fluid moving element is
configured to provide the fluid flow to at least one piece of
electronic equipment.
30. The system of claim 29, wherein the at least one piece of
electronic equipment is stored in at least one rack.
31. The system of claim 30, wherein the desired mass flow of the
fluid is greater than a mass flow range of a second mass flow of
the fluid taken in by the at least one rack.
32. The system of claim 30, wherein the desired mass flow of the
fluid is at least as great as a second mass flow of the fluid taken
in by the at least one rack.
33. The system of claim 30, wherein the fluid moving element is
configured to provide the fluid flow to a data center room in which
the at least one rack is disposed.
34. The system of claim 28, further comprising a sensor configured
to measure at least one physical characteristic and transmit a
representation of the at least one physical characteristic to the
controller, and wherein the at least one indication of the desired
mass flow includes the representation.
35. The system of claim 34, wherein the at least one physical
characteristic include at least one volume of the fluid flow taken
in by at least one housing of at least one object.
36. The system of claim 35, wherein the at least one object
includes at least one piece of electronic equipment and the housing
includes at least one rack.
37. The system of claim 23, wherein the fluid moving element
includes at least one fan.
38. The system of claim 23, wherein the controller is configured to
control the at least one parameter of the cooling element based on
at least one stored value indicating at least one parameter
value.
39. The system of claim 38, wherein the at least stored value
indicates the at least one parameter value corresponding to at
least one available cooling capacity of the cooling element.
40. The system of claim 23, wherein the controller is configured to
control the at least one parameter of the fluid moving element
based on at least one stored value indicating at least one
parameter value.
41. The system of claim 40, wherein the at least stored value
indicates the at least one parameter value corresponding to at
least one available mass flow of fluid from the fluid moving
element.
42. The system of claim 23, wherein the controller is further
configured to adjust at least one of the at least one parameter of
the cooling element and the at least one parameter of the fluid
moving element based on at least one monitored cooling condition to
maintain the predetermined temperature and provide the desired mass
flow of the fluid.
43. The system of claim 42, wherein the at least one cooling
condition includes at least one of a current mass flow of fluid to
current cooling capacity ratio, a pressure loss, a temperature, and
a temperature change.
44. The system of claim 42, wherein the controller is configured to
adjust the at least one of at least one parameter of the cooling
element and the at least one parameter of the fluid moving element
based on the at least one monitored cooling condition to maintain
the predetermined temperature and provide the desired mass flow of
the fluid without temperature and mass flow of fluid spikes.
45. The system of claim 42, further comprising at least one sensor
configured to measure the at least one cooling condition and
transmit a representation of the cooling condition to the
controller.
46. A method of cooling at least one equipment rack with a fluid
flow, the method comprising: generating at least one first stored
value indicating at least one first cooling parameter value for a
cooling device configured to generate the fluid flow; providing the
fluid flow from the cooling device at a first predetermined
temperature and a first output mass flow of the fluid flow;
measuring a change in an intake mass flow to the at least one
equipment rack; determining a first chosen cooling parameter value
from the at least one first stored value, wherein the cooling
device using the first chosen cooling parameter value generates a
second mass flow of the fluid flow that is closer to the intake
mass flow than the first mass flow of the fluid flow; generating at
least one second stored value indicating at least one second
cooling parameter value for the cooling device; determining a
second chosen cooling parameter value from the at least one second
stored value, wherein the cooling device using the second chosen
cooling parameter value and the first chosen cooling parameter
value maintains the predetermined temperature of the fluid flow and
the second mass flow of the fluid flow; and adjusting the cooling
device to use the first and second chosen cooling parameter
values.
47. The method of claim 46, further comprising: monitoring at least
one physical characteristic; and adjusting at least one of the
first and second cooling parameter values, based, at least in part,
on the monitored physical characteristic so that the cooling device
generates a third mass flow of the fluid flow that is closer to the
intake mass flow than the second mass flow of fluid.
48. The method of claim 46, wherein maintaining the predetermined
temperature includes limiting an amount of change in a current
temperature of the fluid flow.
49. The method of claim 48, wherein the amount of change includes a
change of two degrees Fahrenheit per minute and five degrees
Fahrenheit per hour.
50. The method of claim 46, wherein the fluid flow includes an air
flow.
51. The method of claim 46, wherein the first cooling parameter
includes a fan speed and the second cooling parameter includes a
compressor speed.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of Invention
[0002] Embodiments of the invention relate generally to devices and
methods for cooling electronic equipment. Specifically, aspects of
the invention relate to methods of cooling electronic equipment by
providing a relatively constant temperature air flow to the
equipment.
[0003] 2. Discussion of Related Art
[0004] Heat produced by electronic equipment can have adverse
effects on the performance, reliability and useful life of the
equipment. Over the years, as electronic equipment becomes faster,
smaller, and more power consuming, such equipment also produces
more heat, making control of heat more critical to reliable
operation.
[0005] A typical environment where heat control may be critical
includes a data center containing racks of electronic equipment,
such as servers and CPUs. As demand for processing power has
increased, data centers have increased in size so that a typical
data center may now contain hundreds of such racks. Furthermore, as
the size of electronic equipment has decreased, the amount of
electronic equipment in each rack and power consumption of the
equipment has increased. An exemplary industry standard rack is
approximately six to six-and-a-half feet high, by about twenty-four
inches wide, and about forty inches deep. Such a rack is commonly
referred to as a "nineteen inch" rack, as defined by the
Electronics Industries Association's EIA-310-D standard.
[0006] To address the heat generated by electronic equipment, such
as the rack-mounted electronic equipment of a modern data center,
air cooling devices have been used to provide a flow of cool air to
the electronic equipment. In the data center environment, such
cooling devices are typically referred to as computer room air
conditioner ("CRAC") units. These CRAC units intake warm air from
the data center and output cooler air into the data center. The
temperature of air taken in and output by such CRAC units may vary
depending on the cooling needs and arrangement of a data center. In
general, such CRAC units intake room temperature air at about
72.degree. F. and discharge cooler air at below about 60.degree.
F.
[0007] The electronic equipment in a typical rack is cooled as the
cool air is drawn into the rack and over the equipment. The air is
heated by this process and exhausted out of the rack. Data centers
may be arranged in various configurations depending on the purposes
of the data center. Some configurations include a room-oriented
configuration in which cool air is output in general to the data
center room. Other configurations include a row-oriented
configuration in which CRAC units and equipment racks are arranged
to produce hot and cold air aisles. Still other configurations
include a rack-oriented configuration in which each rack has a
dedicated CRAC unit.
SUMMARY OF INVENTION
[0008] One aspect of the invention includes a method of cooling. In
some embodiments, the method includes providing a fluid flow at a
predetermined temperature, and adjusting at least one cooling
parameter of at least one cooling device to maintain the
predetermined temperature of the fluid flow when a desired mass
flow of the fluid flow changes.
[0009] In some embodiments, maintaining the predetermined
temperature comprises limiting an amount of change in a current
output temperature of the fluid flow. In one embodiment, the amount
of change is limited to two degrees Fahrenheit per minute and five
degrees Fahrenheit per hour from the predetermined temperature. In
one embodiment, the fluid flow includes an air flow. In some
embodiments, the at least one cooling parameter includes at least
one speed of a compressor of the at least one cooling device. In
one embodiment, the at least one speed of the compressor
corresponds to a cooling capacity of the at least one cooling
device.
[0010] In some embodiments, the method further comprises changing
the mass flow of the fluid flow, based on at least one
representation of the desired mass flow of the fluid flow. In some
embodiments, the method further comprises receiving the at least
one representation of the desired mass flow of the fluid flow. In
some embodiments, providing a fluid flow at the predetermined
temperature includes providing the fluid flow to at least one piece
of electronic equipment. In some embodiments, the at least one
piece of electronic equipment is stored in at least one rack, and
the method includes providing the fluid flow to the at least one
rack. In some embodiments, the desired mass flow of the fluid flow
is greater than a second mass flow of the fluid flow taken in by
the at least one rack. In some embodiments, the desired mass flow
of the fluid flow is at least as great as a second mass flow of the
fluid flow taken in by the at least one rack. In some embodiments,
the method includes providing the fluid flow to a data center room
in which the at least one rack is disposed.
[0011] In some embodiments, the method further comprises measuring
at least one physical characteristic on which the at least one
representation of the desired mass flow of the fluid flow is based.
In one embodiment, the at least one physical characteristic
includes at least one mass flow of the fluid flow taken in by at
least one housing of an object. In some embodiments, adjusting the
at least one cooling parameter comprises changing at least one fan
speed of the at least one cooling device based, at least in part,
on the at least one representation of the desired mass flow of the
fluid flow. In some embodiments, adjusting the at least one cooling
parameter comprises changing the at least one fan speed of the at
least one cooling device based, at least in part, on a mapping of
fan speed to output mass flow of fluid. In some embodiments,
adjusting the at least one cooling parameter comprises adjusting
the at least one cooling parameter based on at least one stored
value indicating at least one cooling parameter value. In one
embodiment, the at least one stored value indicates at least one
cooling parameter value corresponding to at least one of a desired
cooling capacity of the at least one cooling device.
[0012] In some embodiments, the method, further comprises
monitoring at least one cooling condition, and adjusting the at
least one cooling parameter based on a change in the at least one
cooling condition to maintain the desired mass flow of the fluid
flow and the predetermined temperature. In some embodiments, the at
least one cooling condition includes at least one of a current mass
flow of fluid to current cooling capacity ratio, a pressure loss, a
temperature, and a temperature change. In some embodiments,
adjusting the at least one cooling parameter based on the change in
the at least one cooling condition includes adjusting the at least
one cooling parameter to avoid spikes in the mass flow of the fluid
and a current output temperature of the fluid.
[0013] In one aspect, the invention includes a system for providing
a fluid flow at a predetermined temperature. In some embodiments,
the system comprises a cooling element configured to cool the fluid
flow, a fluid moving element configured to provide the fluid flow,
and a controller configured to control at least one parameter of at
least one of the cooling element and the fluid moving element to
maintain the fluid flow at the predetermined temperature and at a
desired mass flow of the fluid.
[0014] In some embodiments, to maintain the fluid flow at the
predetermined temperature, the controller is configured to limit an
amount of changing in a current output temperature of the fluid
flow. In some embodiments, the amount of change is less than two
degrees Fahrenheit per minute and five degrees Fahrenheit per hour.
In some embodiments, the fluid flow includes an air flow. In some
embodiments, the cooling element includes at least one compressor,
and the at least one cooling parameter includes at least one speed
of the compressor. In some embodiments, the controller is
configured to receive at least one indication of the desired mass
flow of the fluid.
[0015] In some embodiments, the fluid moving element is configured
to provide the fluid flow to at least one piece of electronic
equipment. In some embodiments, the at least one piece of
electronic equipment is stored in at least one rack. In some
embodiments, the desired mass flow of the fluid is greater than a
mass flow range of a second mass flow of the fluid taken in by the
at least one rack. In some embodiments, the desired mass flow of
the fluid is at least as great as a second mass flow of the fluid
taken in by the at least one rack. In some embodiments, the fluid
moving element is configured to provide the fluid flow to a data
center room in which the at least one rack is disposed. In some
embodiments, the system further comprises a sensor configured to
measure at least one physical characteristic and transmit a
representation of the at least one physical characteristic to the
controller, and wherein the at least one indication of the desired
mass flow includes the representation. In some embodiments, the at
least one physical characteristic include at least one volume of
the fluid flow taken in by at least one housing of at least one
object. In some embodiments, the at least one object includes at
least one piece of electronic equipment and the housing includes at
least one rack. In some embodiments, the fluid moving element
includes at least one fan. In some embodiments, the controller is
configured to control the at least one parameter of the cooling
element based on at least one stored value indicating at least one
parameter value. In some embodiments, the at least stored value
indicates the at least one parameter value corresponding to at
least one available cooling capacity of the cooling element. In
some embodiments, the controller is configured to control the at
least one parameter of the fluid moving element based on at least
one stored value indicating at least one parameter value. In some
embodiments, the at least stored value indicates the at least one
parameter value corresponding to at least one available mass flow
of fluid from the fluid moving element. In some embodiments, the
controller is further configured to adjust at least one of the at
least one parameter of the cooling element and the at least one
parameter of the fluid moving element based on at least one
monitored cooling condition to maintain the predetermined
temperature and provide the desired mass flow of the fluid. In some
embodiments, the at least one cooling condition includes at least
one of a current mass flow of fluid to current cooling capacity
ratio, a pressure loss, a temperature, and a temperature change. In
some embodiments, the controller is configured to adjust the at
least one of at least one parameter of the cooling element and the
at least one parameter of the fluid moving element based on the at
least one monitored cooling condition to maintain the predetermined
temperature and provide the desired mass flow of the fluid without
temperature and mass flow of fluid spikes. In some embodiments, the
system further comprises at least one sensor configured to measure
the at least one cooling condition and transmit a representation of
the cooling condition to the controller.
[0016] In one aspect, the invention comprises a method of cooling
at least one equipment rack with a fluid flow. In some embodiments,
the method comprises generating at least one first stored value
indicating at least one first cooling parameter value for a cooling
device configured to generate the fluid flow, providing the fluid
flow from the cooling device at a first predetermined temperature
and a first output mass flow of the fluid flow, measuring a change
in an intake mass flow to the at least one equipment rack,
determining a first chosen cooling parameter value from the at
least one first stored value, wherein the cooling device using the
first chosen cooling parameter value generates a second mass flow
of the fluid flow that is closer to the intake mass flow than the
first mass flow of the fluid flow, generating at least one second
stored value indicating at least one second cooling parameter value
for the cooling device, determining a second chosen cooling
parameter value from the at least one second stored value, wherein
the cooling device using the second chosen cooling parameter value
and the first chosen cooling parameter value maintains the
predetermined temperature of the fluid flow and the second mass
flow of the fluid flow, and adjusting the cooling device to use the
first and second chosen cooling parameter values.
[0017] In some embodiments, the method further comprises monitoring
at least one physical characteristic, and adjusting at least one of
the first and second cooling parameter values, based, at least in
part, on the monitored physical characteristic so that the cooling
device generates a third mass flow of the fluid flow that is closer
to the intake mass flow than the second mass flow of fluid. In some
embodiments, maintaining the predetermined temperature includes
limiting an amount of change in a current temperature of the fluid
flow. In some embodiments, the amount of change includes a change
of two degrees Fahrenheit per minute and five degrees Fahrenheit
per hour. In some embodiments, the fluid flow includes an air flow.
In some embodiments, the first cooling parameter includes a fan
speed and the second cooling parameter includes a compressor
speed.
[0018] The invention will be more fully understood after a review
of the following figures, detailed description and claims.
BRIEF DESCRIPTION OF DRAWINGS
[0019] The accompanying drawings are not intended to be drawn to
scale. In the drawings, each identical or nearly identical
component that is illustrated in various figures is represented by
a like numeral. For purposes of clarity, not every component may be
labeled in every drawing. In the drawings:
[0020] FIG. 1 is a perspective view of a cooling unit of an
embodiment of the invention without an external housing;
[0021] FIG. 2A-D are four views showing data center configurations
with each data center configuration being cooled in accordance with
an embodiment of the invention;
[0022] FIG. 3 is a diagram of components of a cooling unit in
accordance with an embodiment of the invention;
[0023] FIG. 4 is a flow chart showing the control of a cooling
device in accordance with an embodiment of the invention; and
[0024] FIGS. 5A and 5B illustrate mappings of cooling information
in accordance with an embodiment of the invention.
DETAILED DESCRIPTION
[0025] This invention is not limited in its application to the
details of construction and the arrangement of components set forth
in the following description or illustrated in the drawings. The
invention is capable of other embodiments and of being practiced or
of being carried out in various ways. Also, the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," "having," "containing," "involving," and variations
thereof herein, is meant to encompass the items listed thereafter
and equivalents thereof as well as additional items.
[0026] In one aspect of the invention, it is recognized that
thermal stress from temperature fluctuations experienced by
electronic equipment may have an adverse affect on the performance,
reliability, and useful life of the electronic equipment. In
particular, disposing CRAC units in a data center room near
equipment racks (e.g., in row-oriented and rack-oriented
arrangements) may increase the temperature fluctuations experienced
by the electronic equipment in the equipment racks (e.g., compared
to room-oriented arrangements). It may be critical in such
arrangements to control the fluctuation of temperature experienced
by the electronic equipment to maintain the proper functionality of
the electronic equipment.
[0027] In general, at least one embodiment of the invention is
directed at cooling an object with a constant temperature fluid
flow to prevent thermal stressors from damaging such electronic
equipment. The object may include electronic equipment that may be
damaged by temperature fluctuations. In at least one embodiment of
the invention, the temperature of the fluid may be maintained by
appropriately adjusting cooling parameters of the cooling device
based on monitored physical characteristics and mapped
relationships.
[0028] At least one embodiment of the invention is directed at
using a CRAC unit to cool an air flow to electronic equipment.
Examples of such CRAC units are disclosed in detail in U.S. patent
application Ser. No. 11/335,874 filed Jan. 19, 2006 and entitled
"COOLING SYSTEM AND METHOD," Ser. No. 11/335,856 filed Jan. 19,
2006 and entitled "COOLING SYSTEM AND METHOD," Ser. No. 11/335,901
filed Jan. 19, 2006 and entitled "COOLING SYSTEM AND METHOD," Ser.
No. 11/504,382 filed Aug. 15, 2006 entitled "METHOD AND APPARATUS
FOR COOLING," and Ser. No. 11/504,370 filed Aug. 15, 2006 and
entitled "METHOD AND APPARATUS FOR COOLING" which are hereby
incorporated herein by reference. One embodiment of a CRAC unit 101
is illustrated in FIG. 1. As shown, the CRAC unit 101 includes a
rack 103 configured to house the components of the CRAC unit 101 in
the manner described below.
[0029] Some implementations of the invention may include InRow RP
Chilled Water Systems available from APC, Corp., West Kingston,
R.I., Network AIR IR 20 KW Chilled Water Systems available from
APC, Corp., West Kingston, R.I., FM CRAC Series Systems available
from APC, Corp., West Kingston, R.I., and/or any other heating or
precision cooling equipment.
[0030] In one embodiment of the invention, the CRAC unit 101 may
include an evaporator 105 configured to cool air. The evaporator
105 may include multiple evaporator coils that may increase a
surface area of the evaporator 105. A coolant may flow within the
evaporator 105 (e.g., within the evaporator coils) in a liquid
form. As air is drawn over the evaporator 105 (e.g., over or
through the evaporator coils), the air may be cooled by the
coolant. The coolant, conversely, may be warmed by the air as the
air is drawn over the evaporator 105 thereby causing the coolant to
evaporate.
[0031] In some embodiments of the invention, the air may be drawn
across the evaporator 105 by one or more fans, each indicated at
107. The fans 107 may be arranged to pull warm air into the CRAC
unit 101 from a direction indicated by arrows A, move the air over
the evaporator 105 so that the air is cooled, and then exhaust the
cooled air from the CRAC unit 101 in a direction indicated by
arrows B. As illustrated in FIG. 1, a plurality of fans 107 may be
used to draw the air through CRAC unit 101.
[0032] Fan 107 may be configured to adjust or otherwise vary their
speed to increase or decrease the volume of air drawn through the
CRAC unit 101 over the evaporator 105. As the fan speed increases,
a larger air mass flow may be drawn through the CRAC unit 101.
Conversely, as the fan speed decreases, a smaller air mass flow may
be drawn through the CRAC unit 101. The fan speed may be
controllable by a controller coupled to the CRAC unit 101, as
described below.
[0033] It should be appreciated that in other implementations of a
CRAC unit (e.g., 101), fans (e.g., 107) may be replaced or
supplemented with one or more other fluid moving or directing
devices, including pumps, pipes, directing surfaces, tubes, etc.
Fluid moving devices may be fully variable, semi-variable or
non-variable. When the term "fan" is used herein it should be
understood to include any fluid moving and/or directing device,
including fans, pumps, pipes, tubes, directing surfaces, etc. When
the term "fan speed" is used herein, it should be understood to
include any regulator of a mass flow of fluid being moved by any
fluid moving device. In one implementation, a fan may include a
dedicated controller configured to adjust fan speed based on an
input signal indicating a measured temperature or other cooling
condition or parameter. The term "mass flow" should be understood
to include any indication of a volume over a period of time.
[0034] In one embodiment, the CRAC unit 101 may further include a
condenser 109 configured to cool the coolant as cool air is drawn
across the condenser 109. The condenser 109 may include multiple
condenser coils to provide a large operational surface area for the
condenser 109. The coolant may flow within the condenser 109 (e.g.,
within the condenser coils) in a gaseous form. As air is drawn over
the condenser 109 (e.g., over or through condenser coils) the
coolant may be cooled by the air thereby causing the coolant to
condense. The air drawn over the condenser may be warmed by the
coolant and exhausted from the CRAC unit 101. In one embodiment,
air may be drawn into the CRAC unit 101 through a plenum along
arrow C so as to move the air over the condenser 109 and out of the
unit along an air path defined by arrows D. Fans may be provided to
achieve the air flow over the condenser 109 as described above.
[0035] In one embodiment, the flow of the coolant through and
between the evaporator 105 and the condenser 109 may be facilitated
by a compressor 111. The compressor 111 may pump coolant through
pipes coupling the compressor 111 to the evaporator 105 and the
condenser 109 so that the coolant is warmed in the evaporator 105
as it cools air and is cooled in the condenser 109 as it warms
air.
[0036] The speed at which the compressor 111 pumps the coolant
through the evaporator 105 may determine a cooling capacity of the
CRAC unit 101 (i.e., amount of heat removed from the air by the
CRAC unit 101 over a period of time as the air moves over the
evaporator 105). If more coolant is pumped to the evaporator 105,
the evaporator 105 may remove a greater amount of heat from the air
flowing over it. If less coolant is pumped to the evaporator 105,
the evaporator 105 may remove a smaller amount of heat from the air
flowing over it.
[0037] In some implementations, a compressor (e.g., 111) may be
fully variable between a minimum and maximum coolant flow rate. In
other implementations, a compressor (e.g., 111) may be non-variable
or semi-variable allowing one or a few discrete coolant flow rates.
In still other implementations, a compressor (e.g., 111) may be
configured as a matrix of multiple compressors acting collectively
to control the flow rate. It should be appreciated that the
invention is not limited to any specific compressor configuration
listed above or otherwise. The flow rate of a compressor (e.g.,
111) may be controlled by a controller coupled to the CRAC unit
101, as described below.
[0038] In one embodiment, the CRAC unit 101 may include or be
coupled to one or more sensors 113 to measure one or more physical
characteristics of the air flow through the CRAC unit 101. The
sensors 113 may include relative humidity sensors, temperature
sensors, pressure sensors, absolute humidity sensors, and/or any
other desired sensors, as discussed in more detail below. The
sensors 113 may be disposed in the CRAC unit 101, as illustrated in
FIG. 1, in a data center room in general, and/or in an electronic
equipment rack. The purpose of the sensors 113 will become apparent
as the description of embodiments of the invention proceeds.
[0039] FIGS. 2A-2D illustrate some exemplary configurations of
various CRAC units in accordance with various embodiments of the
invention. As discussed, CRAC units, such as the CRAC unit 101
shown in FIG. 1, are typically disposed in a data center room. FIG.
2A illustrates a room-based arrangement in which CRAC units 201,
203, 205, and 207 are disposed near the edge of a data center room
and provide general cooling to the entire room, which is filled
with rows of equipment racks, each equipment rack being indicated
at 209. FIG. 2B illustrates a rack-based arrangement in which a
CRAC unit 211 is coupled to an equipment rack 213 to provide
dedicated cooling to that specific equipment rack 213. FIG. 2C
illustrates a row-based arrangement in which equipment racks, each
indicated at 217, form hot aisles and cold aisles. CRAC units 215,
which are interspersed within the equipment racks 215, intake hot
air exhausted by the equipment racks 217 from the hot aisles and
output cold air to the cold aisles to cool the equipment racks 217.
In such a configuration, equipment racks and CRAC units may be
arranged in any ratio (e.g., two equipment units for every one CRAC
unit, etc). FIG. 2D illustrates an alternative row-based
arrangement in which CRAC units 219 and 221 are disposed along the
ceiling of a data center room. The CRAC units 219 and 221 and the
rows of equipment racks 223, 225, 227, and 229 of FIG. 2D form hot
and cold aisles.
[0040] It should be appreciated that the above illustrations of the
CRAC unit 101 of FIG. 1 and CRAC unit arrangements (e.g., FIGS.
2A-D) are given as examples only. Embodiments of the invention are
not limited to any particular arrangement of CRAC units or any
particular CRAC unit. Furthermore, embodiments of the invention are
not limited to CRAC units but, rather, may include any cooling
device configured to cool any object with any fluid, including any
gas and/or liquid.
[0041] FIG. 3 illustrates a block diagram of some components of a
cooling device (e.g., a CRAC unit 101) according to at least one
embodiment of the invention. As described in more detail below,
FIG. 3 illustrates a controller 301, one or more controlled devices
305, 307, and one or more sensors 309, 311, 313, 315 coupled by a
communication network 303.
[0042] In one embodiment, the controller 301 may be dedicated to a
single cooling device (e.g., CRAC unit 101). In another embodiment,
the controller 301 may control a plurality of cooling devices
(e.g., the controller 301 may be part of a main data center control
system or a dedicated cooling system). In one embodiment, the
controller 301 may include a Philips XAG49 microprocessor,
available commercially from the Phillips Electronics Corporation
North America, New York, N.Y. The controller 301 may include a
volatile memory and a static memory that may store information such
as executable programs and other data useable by controller 301.
The controller 301 may be coupled to an external memory device,
such as a hard disk drive (not shown) that may also store
executable programs and other data usable by the controller 301. In
one embodiment, the controller 301 may communicate with other
components of the cooling device over a network 303. The network
303 may include an internal cooling device bus, a local area
network, and/or a wide area network. The network 303 may include a
wired portion (e.g., a portion including a mechanical connection
between two points) and/or a wireless portion (e.g., a portion
without a mechanical connection between two points, such as a Wi-Fi
network).
[0043] As illustrated in FIG. 3, in one embodiment, the network 303
may couple the controller 301 to one or more controlled devices
(e.g., 305 and 307) that regulate a cooling parameter (e.g.,
compressor speed, fan speed, etc.) of a cooling unit (e.g., 101).
In one embodiment, the one or more devices include a compressor 305
and/or a fan 307. The controller 301 may communicate over the
network 303 to adjust a parameter of the compressor 305 and/or the
fan 307. For example, the controller 301 may transmit a control
signal to the compressor 305 indicating a change in compressor
speed. The compressor 305 may receive the control signal from the
network 303 and adjust the speed of coolant flow accordingly. As
another example, the controller 301 may transmit a control signal
to the fan 307 indicating a change in fan speeds. The fan 307 may
receive the control signal from the network 303 and adjust its
speed accordingly.
[0044] In one embodiment, the controller 301 may execute one or
more control loops (e.g., proportional-integral-derivative (PID)
loops) written in a firmware of the controller 301 to determine
when and which control signals should be transmitted to controlled
devices (e.g., 305 and 307). In one embodiment, one control loop
executed by the controller may generate an input for another
control loop executed by the controller. In one embodiment, the
controller 301 may include multiple controllers coupled together.
Each controller may execute one or more control loops. Each control
loop may generate an input for one or more other control loops
executed by one of the other controllers and/or one or more control
signals for one or more controlled devices.
[0045] The control signals may be transmitted to adjust one or more
cooling parameters (e.g., fan speed, compressor speed, etc.) so
that a desired cooling output or other cooling condition may be
maintained by the cooling device, such as a constant temperature, a
constant air mass output, an air output volume that matches an air
intake volume of a cooled device, etc. Such a desired condition,
for example, may be entered by a user of the cooling device (e.g.,
a data center administrator) through a control panel coupled to the
controller 301.
[0046] In one embodiment of the invention, the controller 301 may
be configured to maintain an output air mass flow that roughly
matches an air mass flow taken in by the electronic equipment being
cooled by the cooling device. In one embodiment, controller 301 may
receive an input signal indicating an air mass flow taken in by the
electronic equipment (e.g., from one or more sensors in or out of
the CRAC unit). As discussed in more detail below, the controller
301 may determine a needed fan speed to match the air mass flow
taken in by the electronic equipment. A matching air mass flow may
include an air mass flow greater than the intake air mass flow
and/or an air mass flow within a range of the intake air mass flow.
The controller 301 may then generate one or more control signals to
adjust a fan speed of the controlled devices (e.g., 305, 307) so
that the air mass flow output by the cooling device (e.g., CRAC
unit 101) matches the air mass flow of air taken in by the
electronic equipment. As discussed below, controller 301 may be
configured to adjust other cooling parameters (e.g., the compressor
speed) to maintain a predetermined temperature of the air flow to
the electronic equipment as the fan speed and/or other
characteristics of the environment change (e.g., dust, wear and
tear, efficiency, etc.).
[0047] To facilitate proper control of cooling parameters, in one
embodiment, the controller 301 may be coupled to one or more
sensors 309, 311, 313, and 315. The sensors 309, 311, 313, and 315
may measure physical characteristics or other information relevant
to determining which control signals to send to controlled devices
(e.g., 305, 307) and transmit a representation of the measured
characteristics to the controller 301 through the network 303. The
sensors 309, 311, 313, and 315 may include temperature sensors 309,
relative humidity sensors 311, pressure sensors 313, and any other
sensors 315 that may measure any physical characteristic relevant
to the control of a cooling device. The sensors 309, 311, 313, and
315 may be disposed within a CRAC unit (e.g., 101) or other cooling
device, generally in a data room, in cooled equipment racks, or any
other desired location.
[0048] In one aspect of the invention, it is recognized that the
cooling parameters of the cooling device may be controlled to
provide a predetermined temperate air flow to the electronic
equipment even as air mass flow provided to the electronic
equipment and/or other cooling conditions change. As discussed
above, maintaining a temperature of the air flow may prevent
thermal stress on the electronic equipment from having adverse
effects on the performance, reliability, and useful life of the
equipment. An example process 400 that may be performed to maintain
the temperature is illustrated in FIG. 4. The process 400 may be
widely deployable and both reliably and predictably deliver air at
a predetermined and/or constant temperature. Furthermore, process
400 may be based on easily understandable principals to improve the
speed of deployment since those involved in deployment may readily
understand the underlying principals.
[0049] It should be appreciated that when the terms predetermined
temperature and/or constant temperature are used herein, the terms
may refer to a temperature within a temperature range of a target
temperature so that the electronic equipment does not experience
large variations in temperature. Although in some embodiments the
temperature may be absolutely constant, in other embodiments, the
temperature may vary within the range of acceptable temperature. In
one implementation, the target temperature may include about
sixty-eight degrees Fahrenheit. In one implementation, the range
may include a percentage of the target temperature (e.g., about ten
percent above and/or below the target temperature). In one
implementation, the range may include a number of degrees (e.g.,
five degrees Fahrenheit). In one implementation, the temperature
range may include a change in temperature over time. In one
implementation the temperature range may include a change of about
five degrees Fahrenheit per hour and about two degrees Fahrenheit
per minute.
[0050] In one embodiment, process 400 may begin by generating one
or more mappings of cooling parameters as indicated in block 401.
The cooling parameters may include one or more of a fan speed, a
compressor speed, a compressor frequency, a signal to or from a
fluid or refrigerant flow valve, and signal indicating a mass flow
of fluid or air temperature. These parameters may be mapped to any
number of desired other parameters, cooling conditions, and/or
physical characteristics. Some example mappings are illustrated in
FIGS. 5A and 5B. These mappings may be generated in a lab
environment to mirror the physical world that may be experienced by
the cooling unit in operation. In other embodiments, these mappings
may be computed based on characteristics of the cooling device
and/or may be determined using a computer simulation.
[0051] In one embodiment, the mappings may be generated before the
cooling device is installed in a data center room. In one
embodiment, the mappings may be generated during the manufacture
and/or design of a cooling device (e.g., CRAC unit 101). The
mappings may describe the relationship between a cooling parameter
and one or more variables, for example, in a graph or table.
[0052] The mappings may be generated, for example, by varying input
characteristics and the parameter and monitoring the output of the
cooling unit. For example, fan speed may be mapped to air mass flow
by measuring the output air mass flow while adjusting the fan
speed. The measured output air mass flow may be recorded, for
example, in a table such as table 501 of FIG. 5A. As another
example, the compressor speed may be mapped to cooling capacity by
measuring the output cooling capacity while adjusting the
compressor speed. The output cooling capacity may be determined,
for example by comparing a temperature of an air flow taking in by
the cooling unit to the temperature of cooled air flow output by
the cooling unit. The measured cooling capacity may be recorded,
for example, in a table such as table 503 of FIG. 5B. It should be
appreciated that each mapping may include a dimension for each
variable on which the parameter or condition is being mapped.
[0053] For example, in one embodiment, fan speed may be mapped to a
desired output mass flow of air, a pressure loss over a filter of
the cooling device, a pressure loss over other portions of the
cooling device, and/or any other desired characteristics. A mapping
may include a dimension for each of these variables.
[0054] In one embodiment, for example, compressor speed may be
mapped to cooling capacity, air mass flow, suction pressure of a
CRAC unit (e.g., 101), discharge pressure of a CRAC unit (e.g.,
101), a ratio of air mass flow to cooling capacity, and/or any
other desired characteristic. It should be appreciated that any
mapping may include any number of dimensions corresponding to any
variables that may affect the mapped value, including, physical
characteristic, cooling conditions, and/or cooling parameters.
[0055] In one embodiment, rather than mapping the parameters in a
table or graph, one or more parameters may be defined by one or
more mapping functions or equations. Such mapping functions may
describe the relationship between the variables and the parameter.
In one implementation, the mapping function may be derived from
values obtained through the mapping process described above (e.g.,
a polynomial or other function derived from mapped points on a
graph such as by well-known interpolation methods). It should be
recognized that any set of stored values (e.g. mapped values,
equations, etc.) from which a parameter value may be derived may be
used in some embodiments of the present invention.
[0056] In one embodiment, as indicated in block 403, a CRAC unit
(e.g., 101) may receive an indication of a target temperature at a
target position, for example, from a data center administrator. In
one embodiment, the target temperature may represent a target
output temperature of the CRAC unit. In one embodiment, the target
temperature may represent a target temperature at which the
electronic equipment may be ideally cooled. In one embodiment, the
target temperature may be measurable by a target sensor disposed at
or near the target position.
[0057] In one embodiment, as indicated in block 405, a CRAC unit
(e.g., 101) may begin producing an initial air flow to the
electronic equipment with an air mass flow that matches the intake
air mass flow of the electronic equipment and at a temperature that
matches the target temperature. Sensors may measure various
physical conditions that may be used by the CRAC unit (e.g., 101)
to determine the initial cooling parameters (e.g., fan speed and
compressor speed) to generate this initial air flow. For example,
an intake air mass flow may be measured and used to determine a fan
speed by reference to a fan speed mapping, as described in more
detail below. A desired cooling capacity may be determined from
measured temperature sensors and be used to determine a compressor
speed from a compressor speed mapping, as described in more detail
below.
[0058] In one embodiment, as indicated in block 407, sensors (e.g.,
309, 311, 313, and 315) may measure a current air mass flow taken
in by a cooled electronic equipment rack that differs from the
initial air mass flow of block 405. The sensors (e.g., 309, 311,
313, and 315) may also measure temperatures, pressures, and/or any
other measured characteristics needed to adjust cooling parameters
as described below. The sensors (e.g., 309, 311, 313, and 315) may
transmit an indication of the change in air mass flow and/or any
other characteristics to the CRAC unit (e.g., 101) and/or CRAC unit
controller (e.g., 301). The indication may include a pressure at or
near a fan of the electronic equipment rack from which the intake
air mass flow may be determined. The indication may include a
direct indication of the air mass flow from, for example, an air
mass flow sensor.
[0059] In one embodiment, as indicated in block 409, a CRAC unit
(e.g., 101) and/or CRAC unit controller (e.g., 301) may receive the
indication of a current air mass flow transmitted in block 407. The
CRAC unit (e.g., 101) and/or CRAC unit controller (e.g., 301) may
also receive the indications of other characteristics transmitted
in block 407.
[0060] In one embodiment, as indicated in block 411, a CRAC unit
(e.g., 101) may determine a new fan speed based on the indication
of the intake air mass flow and the other measured characteristics
from block 409. The fan speed may be determined from a mapping of
the fan speed to output air mass flow so that the output air mass
flow of the CRAC unit matches the intake air mass flow of the
electronic equipment. For example, an intake air mass flow of 450
meter.sup.3/hour may be indicated. The CRAC unit may reference
table 501 of FIG. 5A, for example, to determine that a fifty
percent fan speed may generate the desired air mass flow of 450
m.sup.3/h.
[0061] In one embodiment, a new fan speed may be determined such
that the desired output air mass flow is adjusted gradually towards
the measured air mass flow rather than immediately to the measured
air mass flow. For example, a measured air mass flow may be
averaged with measured air mass flows over a period of time to
determine an average air mass flow. Rather than the current air
mass flow, the average air mass flow may be used to determine a new
fan speed. Such averaging may prevent momentary spikes or drops in
air mass flow, for example, from dust or debris moving by a sensor,
from having a drastic effect on the cooling parameters of the CRAC
unit.
[0062] In one implementation, a first controller may determine a
desired air mass flow based, at least in part, on the measured air
mass flow. As described above, the first controller may average the
current air mass flow with the measured air mass flows. The first
controller may transmit a representation of the desired air mass
flow to a second controller. In one implementation, the second
controller may receive the representation and determine the desired
fan speed based on the desired air mass flow by referencing an
appropriate mapping, as described above. It should be appreciated
that although embodiments in which two separate controllers are
used to perform these actions, in other embodiments, a single
controller may be used to perform such action or other desired
action to generate a predetermined temperature cooling output.
[0063] In one embodiment, as indicated in block 413, a CRAC unit
may determine current and desired air mass flow to cooling capacity
ratios. An air mass flow to cooling capacity ratio may be
indicative of a temperature of an air flow output by the CRAC
unit.
[0064] In one embodiment, the current air mass flow to current
cooling capacity ratio may be determined according to:
m c Q c = 1 k * ( T r - T s ) , ( 1 ) ##EQU00001##
where
m c Q c ##EQU00002##
represents the current air flow to current cooling capacity ratio;
k represents the specific heat of air; T.sub.r represents a current
temperature of air taken in for cooling by the CRAC unit (e.g.,
101); T.sub.s represents a current temperature of air supplied by
the CRAC unit to cool the electronic equipment. T.sub.s may
correspond to the current temperature of output air from the CRAC
unit (e.g., 101), the temperature of air taken in by the electronic
equipment, or some other temperature of air at or near a target
location, measured, for example, by a temperature sensor disposed
at or near the target location.
[0065] In one embodiment, the desired air mass flow to desired
cooling capacity ratio may be determined according to:
m d Q d = 1 k * ( T r - T st ) , ( 2 ) ##EQU00003##
where
m d Q d ##EQU00004##
represents the desired air mass flow to current cooling capacity
ratio; k represents the specific heat of air; T.sub.r represents a
current temperature of air taken in by the CRAC unit (e.g., 101)
for cooling; T.sub.st represents a desired temperature of air
supplied by the CRAC unit (e.g., 101) for cooling the electronic
equipment. T.sub.st may correspond to the desired temperature of
output air from the CRAC unit, the temperature of air taken in by
the electronic equipment, or some other temperature of air at a
target location measured by a target sensor.
[0066] In one implementation of the invention, the current and
desired air mass flow to current cooling capacity ratios may be
determined by a first controller. The first controller may execute
a slow PID such that a new desired air mass flow to cooling
capacity ratio is generated by the slow PID that is between the
current air mass flow to current cooling capacity ratio and desired
air mass flow to current cooling capacity ratio. Rather than
continuing the process with the desired air mass flow to current
cooling capacity ratio, the process may continue with the new air
mass flow to current cooling capacity ratio.
[0067] Such an implementation may prevent temporary spikes and
drops in measured values from having a drastic effect on the output
of a CRAC unit (e.g., 101) by producing gradual adjustments in the
cooling parameters. Such temporary spikes may occur, for example,
because a large piece of dust or debris blocks a sensor of the
cooling device, an administrator moves near a temperature sensor,
etc.
[0068] As indicated in block 415, a compressor speed needed to
generate the desired air mass flow to desired cooling capacity
ratio may be determined. The ratio may describe a new air mass flow
that may be generated by the CRAC unit when the fan speed is
adjusted to the new speed determined in block 411 and a new cooling
capacity, as described below. In one embodiment, the new air mass
flow may be set at a target air mass flow that matches the intake
air mass flow. In one embodiment, as described above, the new air
mass flow may be set at the air mass flow used to determine a fan
speed in block 411. The new cooling capacity may then be determined
from the new air mass flow to new cooling capacity ratio according
to:
Q n = m n [ m d Q d ] , ( 3 ) ##EQU00005##
where Q.sub.n equals the new cooling capacity; m.sub.n equals the
new air mass flow that matches the intake air mass flow of the
electronic equipment or other air mass flow used in block 411 to
determine a new fan speed, as described above;
m d Q d ##EQU00006##
equals the desired air mass flow to desired cooling capacity
ratio.
[0069] A compressor speed that corresponds to the new cooling
capacity Q.sub.n may be determined by referencing a mapping of
cooling parameters to cooling capacity. For example, a compressor
speed may be determined from the mapping of table 503 by
referencing a cooling capacity that corresponds to Q.sub.n. As
described above, the mapping may include additional parameters that
may be measured in block 407. As shown, by increasing the
compressor speed, the cooling capacity also increases.
[0070] It should be appreciated that because many characteristics
such as temperature, cooling capacity and pressure may be
continuous, a given mapping may not include every value of such
variables. In some embodiments, this may apply to a cooling
capacity mapping and/or a fan speed mapping, such as the one used
in block 405. In one implementation, if a value of a measured
characteristic is not included in a mapping, a closest neighboring
value of that characteristic may be used in its place. For example,
in table 503, if new cooling capacity equaled 18000 Watts, the
compressor speed of seventy-eight percent may be chosen since the
mapped cooling capacity value 18005 W is closest to the desired new
cooling capacity value 18000 W. In other implementations, the
closest neighboring that is higher than the measured value may be
used. In other implementations, the closest neighboring value that
is lower than the measured value may be used. In still other
implementations, a numerical method may be used to extrapolate a
parameter value of the mapped parameter from neighboring values.
For example, in one implementation, an average value of one or more
neighboring values may be used. It should be appreciated that the
invention is not limited to any particular process of determining a
parameter value from a measured variable.
[0071] In one implementation, the determination of cooling
parameters may be performed by a second controller of the CRAC unit
(e.g., 101). The second controller may receive an indication of the
desired air mass flow to cooling capacity ratio, for example, from
a first controller as described above, and determine the compressor
speed value based on that input along with other sensor input
received by the CRAC unit (e.g., 101), as described above. In one
implementation, the second controller may also receive an
indication of the new air mass flow determined in block 411, as
described above. With this received information from the first
controller and sensors, the second controller may determine a new
compressor speed by reference to one or more mappings, as described
above.
[0072] In one embodiment, as indicated in block 417, a CRAC unit
(e.g., 101) may then adjust the cooling parameters so that they
begin producing the new air mass flow and the new cooling capacity.
In one embodiment, for example, CRAC unit controller (e.g., 301)
may transmit control signals to the fan and compressor of the CRAC
unit (e.g., 101) to adjust their fan speed and compressor speed to
the newly determined values described above.
[0073] As indicated in block 419, in one embodiment, a CRAC unit
(e.g., 101) may continue to monitor physical characteristics and
cooling conditions. For example, the CRAC unit (e.g., 101) may
monitor the current air mass flow to current cooling capacity ratio
for any changes, for example, by using temperature measurements and
Equation 1 above. As another example, pressure sensors may continue
to measure pressure change over a filter of the cooling device. As
the filter fills with dust and other particles, a pressure drop may
increase. An increase in pressure drop may cause a lower air mass
flow to be delivered from the cooling device to the cooled
electronic equipment without a change in the fan speed of a CRAC
unit (e.g., 101). The measurement of the pressure drop may be a
variable in a mapping of the fan speed, so that as the pressure
drop changes, the mapping may be referenced to determine a new fan
speed that may be used to maintain the current air mass flow.
[0074] Such a change in one of the monitored conditions may require
a fan speed change to maintain a total air mass flow provided by
the CRAC unit at a level that matches the air mass flow taken in by
the cooled electronic equipment. In some situations, such a change
may also require a change in compressor speed to maintain an air
mass flow to cooling capacity ratio.
[0075] For example, if a fan speed is changed in a way that affects
the air mass flow, for example, if the fan is not fully variable
and the fan is moved to a higher fan speed that corresponds to a
higher air mass flow, the compressor speed may be adjusted as well
to maintain the air mass flow to cooling capacity ratio. In such a
circumstance, a CRAC unit (e.g., 101) may determine the new air
mass flow that may result if the fan speed is adjusted. Using the
new air mass flow, and the desired air mass flow to cooling
capacity ratio, the CRAC unit may determine a new cooling capacity
using equation 3, as described above. A mapping of compressor speed
may be referenced to determine a compressor speed corresponding to
the new desired cooling capacity, as described above.
[0076] In one embodiment, because measured characteristics (e.g.,
pressure or temperature) or monitored conditions (e.g., current air
mass flow to cooling capacity ratio) may experience sudden spikes
or drops from temporary conditions, as discussed above, cooling
parameters may be adjusted slowly rather than immediately in
response to changes in such characteristics or conditions.
[0077] For example, a CRAC unit may measure a large change in a
current air mass flow to cooling capacity ratio. Rather than
immediately adjusting cooling parameters to return the current air
mass flow to cooling capacity ratio to the desired air mass flow to
cooling capacity ratio, a CRAC unit (e.g., 101) may gradually
adjust the cooling parameters from their current level to the level
that may be needed to produce the desired air mass flow to cooling
capacity ratio.
[0078] In one implementation, to gradually adjust the cooling
parameters, a two controller system may be used, as described
above. A first controller may determine a difference between the
current and desired air mass flow to cooling capacity ratio. The
first controller may determine a new air mass flow to cooling
capacity ratio between the new and desired air mass flow to cooling
capacity ratios. The first controller may transmit the new air mass
flow to cooling capacity ratio to a second controller. The second
controller may determine a new compressor speed based on the new
air mass flow to cooling capacity ratio and the air mass flow being
delivered to the electronic equipment, as described above.
[0079] If any change is determined in block 419, a CRAC unit (e.g.,
101) may adjust the cooling parameters, as indicated in block 421.
The cooling parameters may be adjusted by, for example,
transmitting control signals for a controller (e.g., 301) to the
controlled devices (e.g., 305, 307) through a network (e.g., 303),
as described above.
[0080] By employing such a method, the cooling device may deliver
an air flow to the cooled electronic equipment that is at a mostly
constant temperature even as the air flow and other cooling
parameters and physical characteristics change. It should be
appreciated, however, that the invention is not limited to any
particular set of steps, cooling parameters or measured
characteristics.
[0081] Although embodiments of the invention have been described
with respect to cooling electronic equipment in data center
environments, it should be recognized that embodiments of the
invention are not so limited. Rather, embodiments of the inventions
may be used to provide cooling in any environment to any object
and/or space. For example, embodiments of the invention may be used
with telecommunication equipment in outdoor environments or
shelters, telecommunication data centers, and/or mobile phone radio
base-stations. Embodiments of the invention may be used to with
precious goods such as art work, books, historic artifacts and
documents, and/or excavated biological matters (for example, for
preservation purposes). Embodiments of the invention may be used
for preservation of meats, wines, spirits, foods, medicines,
biological specimens and samples, and/or other organic substances.
Further embodiments may be used for process optimization in
biology, chemistry, greenhouse, and/or other agricultural
environments. Still other embodiments may be used to protect
against corrosion and/or oxidization of structures (for example,
buildings, bridges, or large structures).
[0082] Having thus described several aspects of at least one
embodiment of this invention, it is to be appreciated various
alterations, modifications, and improvements will readily occur to
those skilled in the art. Such alterations, modifications, and
improvements are intended to be part of this disclosure, and are
intended to be within the spirit and scope of the invention.
Accordingly, the foregoing description and drawings are by way of
example only.
* * * * *