U.S. patent application number 11/592621 was filed with the patent office on 2008-05-08 for continuous cooling capacity regulation using supplemental heating.
This patent application is currently assigned to American Power Conversion Corporation. Invention is credited to Peter Ring Carlsen, David J. Lingrey.
Application Number | 20080105412 11/592621 |
Document ID | / |
Family ID | 39358752 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080105412 |
Kind Code |
A1 |
Carlsen; Peter Ring ; et
al. |
May 8, 2008 |
Continuous cooling capacity regulation using supplemental
heating
Abstract
A method of providing variable cooling includes operating a
cooling element to cool an air flow by a first cooling capacity,
operating a heating element to heat the air flow by a first heating
capacity that adjusts the first cooling capacity towards a first
desired total cooling capacity, determining a second desired total
cooling capacity, controlling the cooling element to cool the air
flow by a second cooling capacity that is greater than the second
desired total cooling capacity, and controlling the heating element
to heat the air flow by a second heating capacity that adjusts the
second cooling capacity towards the second desired total cooling
capacity. Further embodiments and cooling systems are also
disclosed.
Inventors: |
Carlsen; Peter Ring;
(Aalborg, DK) ; Lingrey; David J.; (O'Fallon,
MO) |
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: |
39358752 |
Appl. No.: |
11/592621 |
Filed: |
November 3, 2006 |
Current U.S.
Class: |
165/104.33 ;
165/61; 62/228.1; 62/259.2; 62/56 |
Current CPC
Class: |
H05K 7/20836 20130101;
H05K 7/2079 20130101 |
Class at
Publication: |
165/104.33 ;
165/61; 62/228.1; 62/259.2; 62/56 |
International
Class: |
F28D 15/00 20060101
F28D015/00; F25B 29/00 20060101 F25B029/00; F25B 49/00 20060101
F25B049/00; F25D 23/00 20060101 F25D023/00; F25D 3/00 20060101
F25D003/00 |
Claims
1. A method of providing variable cooling, the method comprising:
A) operating a cooling element to cool an air flow by a first
cooling capacity; B) operating a heating element to heat the air
flow by a first heating capacity that adjusts the first cooling
capacity towards a first desired total cooling capacity; C)
determining a second desired total cooling capacity; D) controlling
the cooling element to cool the air flow by a second cooling
capacity that is greater than the second desired total cooling
capacity; and E) controlling the heating element to heat the air
flow by a second heating capacity that adjusts the second cooling
capacity towards the second desired total cooling capacity.
2. The method of claim 1, wherein the act A comprises cooling a
first portion of the air flow, the act B comprises heating a second
portion of the air flow, and the method further comprises an act of
F) combining the first portion and second portion.
3. The method of claim 1, further comprising an act of F) directing
the air flow to at least one piece of electronic equipment.
4. The method of claim 3, wherein the act F comprises directing the
air flow to a data center room containing the at least one piece of
electronic equipment is stored.
5. The method of claim 3, wherein the act F comprises directing the
air flow to an equipment rack containing the at least one piece of
electronic equipment is stored.
6. The method of claim 1, wherein the act D includes operating the
cooling element at one of a set of discrete cooling capacities at
which the cooling element is capable of operating.
7. The method of claim 6, wherein the act E includes adjusting the
one of the set of discrete cooling capacities by heating the air
flow.
8. The method of claim 6, wherein the cooling element includes at
least one compressor having a set of discrete compressor speeds,
and wherein the act D includes selecting one of the discrete
compressor speeds.
9. A cooling system comprising: a cooling element configured to
cool a fluid flow by a variable cooling capacity to lower a
temperature of the fluid flow; a heating element configured to heat
the fluid flow by a variable heating capacity to raise the
temperature of the fluid flow; and a controller configured to vary
the cooling element and the heating element to generate a variable
total cooling capacity corresponding to a combination of the
variable cooling capacity and the variable heating capacity.
10. The system of claim 9, wherein the cooling element is
configured to cool a first portion of the fluid flow, the heating
element is configured to heat a second portion of the fluid flow,
and the system further comprises a discharge configured to combine
the first portion and the second portion.
11. The system of claim 9, wherein the cooling element includes at
least one compressor configured to move a coolant through a cooling
coil at a coolant flow rate that corresponds to a cooling capacity
of the cooling element.
12. The system of claim 11, wherein the compressor is configured to
operate at one of a set of discrete coolant flow rates at which the
at least one compressor is configured to operate.
13. The system of claim 11, wherein the compressor is configured to
operate at a coolant flow rate above a minimum coolant flow
rate.
14. The system of claim 11, wherein the at least one compressor
includes a plurality of compressors.
15. The system of claim 9, wherein the cooling system further
comprises a discharge configured to direct the fluid flow to at
least one piece of electronic equipment.
16. The system of claim 15, wherein the discharge includes at least
one fan.
17. The system of claim 15, wherein the cooling element, heating
element and discharge are part of a computer room air conditioning
(CRAC) unit.
18. The system of claim 9, wherein the heating element is disposed
in the fluid flow between the cooling element and an object.
19. The system of claim 9, wherein the cooling element is disposed
in the fluid flow between the heating element and an object.
20. A method of providing variable cooling, the method comprising:
determining a desired total cooling capacity of an air flow;
adjusting a cooling device to produce a variable cooling capacity
to the air flow that is at least as great as the desired total
cooling capacity; and in a first mode of operation, if the variable
cooling capacity is greater than the desired total cooling
capacity, adjusting a heating device to lower the variable cooling
capacity towards the desired total cooling capacity.
21. The method of claim 20, further comprising directing the air
flow to at least one piece of electronic equipment.
22. The method of claim 20, wherein adjusting a cooling device to
provide the variable cooling capacity includes adjusting at least
one compressor speed of the cooling device.
23. The method of claim 20, wherein adjusting a heating device to
lower the variable cooling capacity towards the desired total
cooling capacity includes adjusting a power supplied to a heat
exchanger of the heating device.
24. The method of claim 20, wherein the desired total cooling
capacity includes a cooling capacity that reduces a temperature of
the air flow to a target temperature and the variable cooling
capacity includes a cooling capacity that reduces the temperature
of the air flow to a predetermined temperature that is lower than
the target temperature.
25. The method of claim 24, wherein the first mode of operation
includes when the predetermined temperature differs from the target
temperature by at least a threshold amount.
26. The method of claim 25, wherein the threshold amount includes
about five degrees Fahrenheit.
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 providing variable cooling
capacity to electronic equipment by supplementing a cooling device
with a heating device.
[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 generally 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
and needs 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.
[0008] A CRAC unit, as well as other typical cooling devices, may
include an evaporator that cools air as the air flows over the
evaporator's coils. Coolant flows within the evaporator's coils and
evaporates as the coolant is warmed by the air passing through or
over the coils. To re-cool the coolant, a cooling device may
include a condenser. Cool air flows through or over the coils of
the condenser causing warm coolant to cool and condense as it flows
within the condenser's coils. A compressor may control the rate of
coolant flow within the coils of the evaporator and the condenser
so that as the compressor speed increases, the rate of coolant flow
increases as well, resulting in more cooling of the air flowing
through the CRAC unit.
[0009] Compressors may be limited in operation to a set of discrete
speeds or a range of variable speeds that correspond to cooling
capacities of the cooling device. Some compressors may be
non-variable such that when the cooling device operates, the
compressor provides only one cooling capacity (i.e., only one
change in the heat of air passing through the cooling coils over a
period of time). In some cooling devices, a matrix of such
non-variable compressors may be combined to act as a semi-variable
compressor. Such a matrix may provide discrete steps of cooling
capacities corresponding to the numbers of compressors in
operation.
[0010] Other compressors are semi-variable such that they provide a
variable cooling capacity over a minimum threshold value, but do
not operate below that threshold level. Operation of such variable
compressors below the minimum threshold level may result in
compressor failure due to motor burnout, burning of bearings,
and/or overheating. Some compressors may be further limited in
their variability to a limited number of compressor speed changes
over a period of time.
SUMMARY OF INVENTION
[0011] One aspect of the invention includes a method of providing
variable cooling. In one embodiment, the method comprises operating
a cooling element to cool an air flow by a first cooling capacity,
operating a heating element to heat the air flow by a first heating
capacity that adjusts the first cooling capacity towards a first
desired total cooling capacity, determining a second desired total
cooling capacity, controlling the cooling element to cool the air
flow by a second cooling capacity that is greater than the second
desired total cooling capacity, and controlling the heating element
to heat the air flow by a second heating capacity that adjusts the
second cooling capacity towards the second desired total cooling
capacity.
[0012] In one embodiment, cooling the air flow comprises cooling a
first portion of the air flow, heating the air flow comprises
heating a second portion of the air flow, and the method further
comprises an act of combining the first portion and second portion.
In some embodiments, the further comprises directing the air flow
to at least one piece of electronic equipment. In one embodiment,
directing the air flow comprises directing the air flow to a data
center room containing the at least one piece of electronic
equipment is stored. In one embodiment, directing the air flow
comprises directing the air flow to an equipment rack containing
the at least one piece of electronic equipment is stored.
[0013] In some embodiments, controlling the cooling element
includes operating the cooling element at one of a set of discrete
cooling capacities at which the cooling element is capable of
operating. In one embodiment, controlling the cooling element
includes adjusting the one of the set of discrete cooling
capacities by heating the air flow. In one embodiment, the cooling
element includes at least one compressor having a set of discrete
compressor speeds, and controlling the cooling element includes
selecting one of the discrete compressor speeds.
[0014] One aspect of the invention includes a cooling system. In
some embodiments, the cooling system comprises a cooling element
configured to cool a fluid flow by a variable cooling capacity to
lower a temperature of the fluid flow, a heating element configured
to heat the fluid flow by a variable heating capacity to raise the
temperature of the fluid flow, and a controller configured to vary
the cooling element and the heating element to generate a variable
total cooling capacity corresponding to a combination of the
variable cooling capacity and the variable heating capacity.
[0015] In some embodiments, the cooling element is configured to
cool a first portion of the fluid flow, the heating element is
configured to heat a second portion of the fluid flow, and the
system further comprises a discharge configured to combine the
first portion and the second portion. In some embodiments, the
cooling element includes at least one compressor configured to move
a coolant through a cooling coil at a coolant flow rate that
corresponds to a cooling capacity of the cooling element. In one
embodiment, the compressor is configured to operate at one of a set
of discrete coolant flow rates at which the at least one compressor
is configured to operate. In one embodiment, the compressor is
configured to operate at a coolant flow rate above a minimum
coolant flow rate. In one embodiment, the at least one compressor
includes a plurality of compressors.
[0016] In some embodiments, the cooling system further comprises a
discharge configured to direct the fluid flow to at least one piece
of electronic equipment. In one embodiment, the discharge includes
at least one fan. In one embodiment, the cooling element, heating
element and discharge are part of a computer room air conditioning
(CRAC) unit. In one embodiment, the heating element is disposed in
the fluid flow between the cooling element and an object. In one
embodiment, the cooling element is disposed in the fluid flow
between the heating element and an object.
[0017] One aspect of the invention includes a method of providing
variable cooling. In some embodiments, the method comprises
determining a desired total cooling capacity of an air flow,
adjusting a cooling device to produce a variable cooling capacity
to the air flow that is at least as great as the desired total
cooling capacity, and in a first mode of operation, if the variable
cooling capacity is greater than the desired total cooling
capacity, adjusting a heating device to lower the variable cooling
capacity towards the desired total cooling capacity.
In some embodiments, the method further comprises directing the air
flow to at least one piece of electronic equipment. In some
embodiments, adjusting a cooling device to provide the variable
cooling capacity includes adjusting at least one compressor speed
of the cooling device. In some embodiments, adjusting a heating
device to lower the variable cooling capacity towards the desired
total cooling capacity includes adjusting a power supplied to a
heat exchanger of the heating device. In some embodiments, the
desired total cooling capacity includes a cooling capacity that
reduces a temperature of the air flow to a target temperature and
the variable cooling capacity includes a cooling capacity that
reduces the temperature of the air flow to a predetermined
temperature that is lower than the target temperature. In some
embodiments, the first mode of operation includes when the
predetermined temperature differs from the target temperature by at
least a threshold amount. In some embodiments, the threshold amount
includes about five degrees Fahrenheit.
[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;
[0021] FIG. 2 illustrates a schematic view of a heating element
that may be used in an embodiment of the invention;
[0022] FIG. 3 illustrates a schematic view of a portion of a
cooling unit of an embodiment of the invention;
[0023] FIGS. 4A-D are four views showing data center configurations
with each data center configuration being cooled in accordance with
an embodiment of the invention;
[0024] FIG. 5 is a diagram of components of a cooling unit of an
embodiment of the invention;
[0025] FIG. 6 is a flow chart showing the control of a cooling
device in accordance with one embodiment of the invention; and
[0026] FIGS. 7A-D are four graphs illustrating the output of a
cooling device in accordance with embodiments of the invention.
DETAILED DESCRIPTION
[0027] 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.
[0028] In accordance with one aspect of the invention, it is
recognized that temperature fluctuations, as well as over-cooling
and under-cooling may have an adverse effect on the performance,
reliability, and useful life of electronic equipment. As described
above, because a compressor of a typical cooling device is limited
in its variability, typical cooling devices may over-cool,
under-cool, and/or cool with a fluctuating temperature.
[0029] For example, for electronic equipment that has an optimal
temperature at which it should be cooled, at a given air mass flow
(i.e., volume of air flowing through the cooling device over a
period of time), a compressor of the cooling device may need to
provide a specific cooling capacity that corresponds to a
compressor speed that is not one of the discrete operating speeds
available to the compressor. Instead, the compressor may have to
operate at a speed that is either too high and thus over-cools the
electronic equipment or too low and thus under-cools the electronic
equipment. Furthermore, the output temperature of a traditional
cooling device having discrete compressor speeds may fluctuate as
the compressor changes from one speed to another, especially if the
steps between speeds are large.
[0030] As discussed above, even compressors that are variable
between a minimum and maximum compressor speed are limited in
operation to speeds above the minimum operating speed. This minimum
operating speed corresponds to a minimum cooling capacity of a
traditional cooling device. Between the minimum operating speed and
a shutoff state, even these variable compressors are unable to
provide a variable cooling capacity. As described above, this lack
of variable cooling capacity may result in over-cooling,
under-cooling, and/or temperature fluctuations.
[0031] In general, at least one embodiment of the invention is
directed at providing more continuously variable cooling to an
object being cooled with a cooling device by using supplemental
heating. The object may include electronic equipment that may be
damaged by improper cooling (e.g., over-cooling, under-cooling,
cooling with a fluctuating temperature). In accordance with at
least one embodiment of the invention, supplemental heating may
provide more continuously variable cooling, by, for example,
heating an air flow from a cooling device directed to the object to
a temperature between the temperatures that might otherwise be
generated by the cooling device operating at one of the limited
available compressor speeds. It should be appreciated that when
using the term "continuously variable" herein, the term should be
read to include any variability that is more continuous than a
cooling device's compressor operating alone would provide.
[0032] At least one embodiment of the invention is directed at a
CRAC unit. Examples of 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, a rack 103 may be
configured to house components of the CRAC unit 101.
[0033] 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.
[0034] 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 or through the evaporator 105 thereby causing the
coolant to evaporate within the evaporator coils.
[0035] 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 draw warm air into the CRAC
unit 101 from a direction indicated by arrows A, move the air
passed 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. Each fan 107 may be configured to adjust or
otherwise vary a fan speed to increase or decrease the air mass
flow of air drawn through the CRAC unit 101 and over the evaporator
105. As the fan speed increases, a larger air mass flow of air may
be drawn through the CRAC unit 101. Conversely, as the fan speed
decrease, a smaller air mass flow of air 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.
[0036] It should be appreciated that in other implementations of a
CRAC unit (e.g., 101) or other cooling device, fans (e.g., 107) may
be replaced or supplemented with one or more other air and/or other
fluid moving and/or directing devices. Air and/or other fluid
moving and/or directing devices may be fully variable,
semi-variable or non-variable. When the term "fan" is used herein
it should be understood to include any air and/or other fluid
moving and/or directing device, including fans, pipes, tubes,
valves, directing surfaces, pumps, vents, etc. When the term "fan
speed" is used herein, it should be understood to include any
regulator of a mass flow of air or any other fluid being moved by
any air and/or other fluid moving and/or directing device.
[0037] 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. As shown, the condenser 109 may be an
external device and may include multiple condenser coils that may
increase a surface area of 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 the condenser coils) the coolant may be cooled by the air
thereby causing the coolant to condense. As a result, the air 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 (not shown) along arrow C so as to move the air over the
condenser 109 and along an air path defined by arrow D. Fans may be
provided to achieve the air flow over the condenser 109 as
described above. It should be understood that the condenser 109 may
be provided within the CRAC unit 101.
[0038] 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. The result is that coolant is warmed in the
evaporator 105 as it cools air and the coolant is cooled in the
condenser 109 as it warms air. The speed at which the compressor
111 pumps the coolant through the evaporator 105 may determine a
cooling capacity of the evaporator 105 (i.e., amount of heat
removed from the air over a period of time). If a greater volume of
coolant per time is pumped to the evaporator 105, the evaporator
105 may produce a greater cooling capacity. If a lower volume of
coolant per time is pumped to the evaporator 105, the evaporator
105 may produce a smaller cooling capacity.
[0039] 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 that are each
semi-variable, non-variable, or fully-variable between a minimum
and maximum coolant flow rate. In some implementations, a
compressor may be configured with a number of compressor cylinders
and may operate using any number of the cylinders to provide a
discretely variable output. In yet other implementations, a
compressor may be configured with a hot gas bypass to provide some
variable output. 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 compressor, as described
below.
[0040] In one embodiment, the CRAC unit 101 may include one or more
sensors 113, each configured to measure one or more physical
characteristics of the air flow through the CRAC unit 101.
Measurements from the one or more sensors 113 may be used by a
controller, as discussed below, to determine a desired cooling
capacity of the CRAC unit 101. In one implementation, the sensors
may include one or more of pressure, humidity, power consumption,
and temperature sensors. The purpose of the sensors 113 will become
apparent as the description of embodiments of the invention
proceeds.
[0041] In accordance with one aspect of the invention, CRAC unit
101 may include one or more heating elements 115. FIG. 2
illustrates a schematic view of an example heating element 115 that
may be used in one embodiment of the invention. In the heating
element 115 of FIG. 2, a voltage may be applied across a plurality
of heating coils, each indicated at 201. When the voltage is
applied, the heating coils may dissipate heat. A fluid flow (e.g.,
air flow) directed along or near the heating coils may be warmed by
that heat dissipated from the heating coils 201.
[0042] The invention is not limited to any specific type of heating
element; rather, the heating elements may include any type of heat
exchanger or heater, including an air-cooled heat exchanger, a
plate heat exchanger, a gasket heat exchanger, a gas heater, an
electric heater, a hot gas reheat system, a heating element that
uses heated or superheated coolant to supply heat, a gas fired
heater, etc. It should be appreciated that the heating elements may
be any type or combination of types of heating elements that are
capable of heating fluid (e.g., air) used to cool the electronic
equipment.
[0043] In one embodiment, the heating element 115 may provide a
heating output (i.e., amount of heat added to the air over a period
of time) that is more variable than the cooling outputs available
from the compressor 111. In one implementation, the heating element
may provide a completely continuous heating output. In another
implementation, the heating element may be variable between two
available cooling outputs from the compressor 111. In yet another
implementation, the heating element 115 may be capable of
generating a pulsing heat output centered about a desired
temperature generated, for example, by the heating element
switching on and off repeatedly. In such implementations, the
heating element may be configured to switch on and off at a higher
rate than the compressor 111 capable of switching speeds (for
example, because a compressor may only be capable of a limited
number of cooling capacity adjustments in a given time period). In
yet another implementation, the heating element may be capable of
finer adjustments to heating capacity than the adjustments
available to the cooling element, so that the combined output of
the cooling element and heating element may be more variable than
the cooling element operating alone.
[0044] In one embodiment, the heating element 115 may be disposed
in the air flow through CRAC unit 101 such that the heating element
115 may heat the air going to the electronic equipment from CRAC
unit 101. In one implementation, heating element 115 may be
disposed between evaporator 105 and the electronic equipment. In
another implementation, evaporator 105 may be disposed between the
heating element 115 and the electronic equipment. In another
embodiment, evaporator 105 may cool a first portion of the airflow
and the heating element 115 may heat a second portion of the air
flow. The first and second portion of the air flow may be combined
to form the full air flow after the respective portions are heated
and cooled. FIG. 3 illustrates a schematic view of a CRAC unit
configured to divide an air flow into the first and second potions
with a diverter 301, heat the first portion of the air flow with a
heating element 303 and cool the second portion with a cooling
element 305. The CRAC unit of FIG. 3 may then combine the first and
second portions and output the combined air flow.
[0045] FIGS. 4A-4D illustrate some exemplary configurations of
various CRAC units (e.g., 101) in accordance with various
embodiments of the invention. As discussed, CRAC units (e.g., 101)
are typically disposed in a data center room. FIG. 4A illustrates a
room-based arrangement in which CRAC units 401, 403, 405, and 407
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 row indicated at 409. FIG. 4B illustrates a
rack-based arrangement in which a CRAC unit 411 is coupled to an
equipment rack 413 to provide dedicated cooling to that specific
equipment rack 413. FIG. 4C illustrates a row-based arrangement in
which CRAC units each indicated at 415 are disposed or otherwise
interspersed within rows of equipment racks, each equipment rack
indicated at 417, to form hot aisles and cold aisles. The CRAC
units 415 intake hot air exhausted by the equipment racks 417 from
the hot aisles and output cold air to the cold aisles to cool the
equipment racks 417. 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. 4D illustrates an alternative
row-based arrangement in which CRAC units 419 and 421 are disposed
along the ceiling of a data center room. The CRAC units 419 and 421
and the rows of equipment racks 423, 425, 427, and 429 of FIG. 4D
form hot and cold aisles.
[0046] It should be appreciated that the above illustrations of the
CRAC unit 101 in FIG. 1 and of CRAC unit configurations (e.g.,
FIGS. 4A-D) are given as examples only. Embodiments of the
invention are not limited to any particular configuration 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.
[0047] Furthermore, while the above descriptions may describe
air-based cooling devices, it should be appreciated that the
invention is not limited to air-based cooling devices. Rather, at
least one embodiment of the invention may include any cooling
device that provides cooling to any object by cooling any fluid.
The fluid may include a gas and/or a liquid. Any reference to
cooling devices or CRAC units should be understood to apply to any
cooling devices using any fluid to cool any object.
[0048] FIG. 5 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. 5 illustrates a controller 501, one or more controlled devices
505, 507, such as heating and cooling elements, and one or more
sensors 509, 511, 513, 515 coupled by a communication network
503.
[0049] In one embodiment, the controller 501 may be dedicated to a
single cooling device (e.g., CRAC unit 101). In another embodiment,
the controller 501 may control a plurality of cooling devices
(e.g., controller 501 may be part of a main data center control
system or a dedicated cooling system). In one embodiment, the
controller 501 may include a Philips XAG49 microprocessor,
available commercially from the Phillips Electronics Corporation
North America, New York, N.Y. The controller 501 may include a
volatile memory and a static memory that may store information such
as executable programs and other data useable by the controller
501. The controller 501 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 501. In
various implementations, the controller 501 may include an analogue
electric controller, a digital electric controller, a fluid or gas
pressure logic device, and/or a mechanical logic device.
[0050] In one embodiment, the controller 501 may communicate with
other components of the cooling device over a network 503. The
network 503 may include an internal cooling device bus, a local
area network, and/or a wide area network. The network 503 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).
[0051] As illustrated in FIG. 5, in one embodiment, the network 503
may couple the controller 501 to a cooling element 505 and a
heating element 507. In one embodiment, the cooling element 505 may
include a component of the cooling unit such as a compressor (e.g.,
105) and/or a fan (e.g., 107), as described above. The controller
501 may communicate over the network 503 to adjust a parameter of
the cooling element 505 such as a compressor speed and/or fan
speeds. For example, the controller 501 may transmit a control
signal to the cooling element 505 indicating a change in compressor
speed; The cooling element 505 may receive the control signal from
the network 503 and adjust the compressor speed accordingly. As
another example, the controller 501 may transmit a control signal
to the cooling element 505 indicating a change in fan speed.
Cooling element 505 may receive the control signal from the network
503 and adjust the fan speed accordingly.
[0052] Substantially similarly, the controller 501 may communicate
over the network 503 to adjust a parameter of the heating element
507. In one embodiment, the controller 501 may transmit a control
signal to the heating element 507 indicating a change in heating
output. The heating element 507 may receive the control signal and
adjust the heating output accordingly. In one implementation, the
heating element 507 may generate a constant heating output. In one
implementation, the heating output of the heating element 507 may
be controlled by adjusting a power level supplied to the heating
element or a portion of the heating element. In one implementation
the control signal may include an indication of the level of power
to be supplied to the heating element 507 and the control signal
may be transmitted to a power level controller of the heating
element 507. In one implementation, the heating element 507 may
generate a pulsing heat output that varies around a target heat
output. In one embodiment, the controller 501 may transmit a pulse
width modulated (PWM) control signal configured to operate the
heating element 507 to provide a desired heating output. In one
implementation, the percentage of high voltage time in the PWM
signal may correspond with the amount of time in which the heating
element 507 is generating heat. In one implementation, the high
voltage time may be extended to increase the heating output and
shortened to decrease the heating output.
[0053] In one embodiment, the controller 501 may execute one or
more control loops (e.g., proportional-integral-derivative (PID)
loops) written in a firmware of the controller 501 to determine
when and which control signals should be transmitted to controlled
devices (e.g., 505 and 507). The control signals may be transmitted
to adjust one or more cooling parameter of the cooling element 505
and one or more heating parameters (e.g., power supplied to the
heating element) of the heating element 507 so that a desired
cooling output or other cooling condition may be maintained by the
CRAC unit (e.g., 101). Such a desired condition may, for example,
be entered by a user of the cooling device (e.g., a data center
administrator) through a control panel coupled to the controller
501.
[0054] In one embodiment, the controller 501 may be configured to
maintain a near constant air output temperature. As described
below, in one aspect of the invention, it is recognized that the
output air temperature of a cooling device may be adjusted by a
heating element to provide more fully variable cooling. In
general,
Cooling Provided=Output of Cooling Elements-Output of Heating
Elements. (1)
To be more accurate, additional heat produced by other elements of
a cooling device may be accounted for, including heat produced by
fans, heat produced by electronics of the cooling device, heat
produced by a compressor, and/or heat produced by any other
source.
[0055] For example, a cooling capacity of 1200 Watts may be
required to cool the air flow passing through a cooling device to a
desired temperature. The compressor speeds available to the cooling
element 505 may provide only for cooling capacities of zero Watts,
one thousand Watts and two thousand Watts. The desired cooling
output of 1200 Watts may be generated by, for example, operating
the compressor at the two thousand Watt level and heating the air
with the heating element 507 by eight hundred Watts.
[0056] To that end, the controller 501 may determine the cooling
capacity of the cooling element 505 and transmit a control signal
to the cooling element 505 to increase the compressor speed as
needed. The controller 501 may also determine the desired heating
output of the heating element 507 and transmit a control signal to
heating element 507 to adjust the heating output as needed.
[0057] To facilitate proper control of cooling parameters, some
embodiments of the controller 501 and the network 503 may be
coupled to one or more sensors 509, 511, 513, and 515. The sensors
509, 511, 513, and 515 may measure physical characteristics
relevant to determining which control signals to send to controlled
devices (e.g., 505, 507). The sensors 509, 511, 513, 515 may
include temperature sensors 509, relative humidity sensors 511,
pressure sensors 513, and/or any other sensors 515 that may measure
any physical characteristic relevant to the control of a cooling
device (e.g., absolute humidity, power consumption, etc.). In one
embodiment, each of the sensors 509, 511, 513, 515 may communicate
the measured physical characteristics to the controller 501 through
the network 503. The measured physical characteristic may be
communicated, in various implementations, by any method, including
analogue electric, digital electric, pressure, mechanical, and any
combination thereof. The controller 501 may then generate
appropriate control signals based on the received information.
[0058] In one aspect of the invention, a cooling device (e.g., CRAC
unit 101) may perform a process (e.g., 600) as illustrated in FIG.
6 so that the cooling device provides continuously variable cooling
to an object. A set of graphs illustrating cooling output of
cooling devices in operation according to some embodiments of the
invention is shown in FIGS. 7A-D. The x-axis of graphs 701, 703,
705, and 707 of FIGS. 7A-D represent a desired cooling capacity.
The y-axis of graphs 701, 703, 705, and 707 of FIGS. 7A-D represent
a delivered cooling capacity.
[0059] Graph 701 of FIG. 7A illustrates the output of a cooling
element (e.g., 505) having three states (off, one hundred percent
cooling capacity, and fifty percent cooling capacity) and a heating
element (e.g., 507) that is completely continuously variable,
allowing a fully continuous combined output. Graph 703 of FIG. 7B
illustrates the output of a cooling element having three states
(off, one hundred percent cooling capacity, and fifty percent
cooling capacity) and a heating element that is has five output
states between each of the cooling element's output states,
allowing a step-like continuous combined output. Graph 705 of FIG.
7C illustrates the output of a cooling element that is fully
variable above an initial minimum output and a heating element that
is completely continuously variable, allowing a fully continuous
combined output even below the minimum output of the cooling
element. Graph 707 of FIG. 7D illustrates an alternative operation
of a cooling element that is fully variable over an initial minimum
output and a heating element that is completely continuously
variable, allowing a fully continuous combined output.
[0060] As indicated in block 601 of FIG. 6, in one embodiment,
process 600 may begin with a cooling device (e.g., 101) determining
a desired total cooling capacity (i.e., reduction in heat of air
flowing through the cooling device over a period of time) based on
a desired cooling condition and various sensor inputs. For example,
a desired cooling capacity may be calculated by:
Q=.DELTA.t*m*k, (2)
where Q is the desired cooling capacity, .DELTA.t is the desired
difference in temperature between the intake air and air provided
to the electronic equipment, m is the air mass flow of air moving
through the cooling device (i.e., volume of air moving through the
cooling device over a period of time), and k is the specific heat
of air (e.g., 1,024 kJ/(kg*K)).
[0061] After determining the desired cooling capacity, a cooling
device (e.g., CRAC unit 101) may adjust one or more cooling
parameters (e.g., compressor speed) to generate a cooling capacity
that is at least as great as the desired cooling capacity. As
indicated in block 603, a controller (e.g., 501) may generate and
transmit a control signal to change the cooling capacity of the
cooling element so that a cooling element (e.g., 505) generates the
new cooling capacity. Generated cooling capacities of cooling
elements in accordance with at least one embodiment of the
invention are illustrated by lines 709, 711, 713, and 715 of FIGS.
7A-D, respectively. As illustrated, the cooling capacities provided
by the cooling elements alone may exceed the desired cooling
capacity.
[0062] In one embodiment, the values of the one or more cooling
parameters (e.g., compressor speed) may be determined, for example,
based on a mapping of cooling parameter values to generated cooling
capacities. Such a mapping may be generated and stored in a memory
of the controller during the design and/or manufacturing process of
the CRAC unit. In another embodiment, an equation may describe the
relationship between the cooling parameters and the generated
cooling capacity so that the cooling parameters may be determined
from the equation using the desired cooling capacity as a variable
value.
[0063] As indicated in block 605, in one embodiment, a cooling
device (e.g., CRAC unit 101) may determine if the output cooling
capacity of the cooling element exceeds the desired cooling
capacity. If the output cooling capacity of the cooling element
does not exceed the desired cooling capacity, but rather equals the
desired cooling capacity, the cooling device may end process 600,
or revert back to the beginning of process 600 to begin the process
again.
[0064] However, if the cooling capacity of the cooling element
alone is greater than the desired cooling capacity, the cooling
device may operate a heating element (e.g., 507) to move the total
cooling capacity of the cooling device towards the desired cooling
capacity, as indicated in block 607. In one implementation, the
desired heating output of the heating element may first be
determined by:
Desired Heating Output=Cooling From Cooling Elements--Desired
Cooling. (3)
[0065] One implementation of operating a heating element comprising
a plurality of heaters using pulse width modulated control signals
is disclosed in is described in U.S. patent application Ser. No.
______ by Carlsen, et. al., filed Nov. 3, 2006, entitled
"MODULATING ELECTRICAL REHEAT WITH CONTACTORS," and having attorney
docket number A2000-706119, and which is hereby incorporated herein
by reference
[0066] In one embodiment, the cooling device may adjust the heating
element to generate a heating output equal to or relatively close
(e.g., to a level that when combined with the cooling capacity
produced by the cooling element would bring the total cooling
output of the cooling device closer to the total desired cooling
output) to the desired heating output. In one embodiment, a
controller (e.g., 501) may generate and transmit a control signal
over a network (e.g., 503) to the heating element (e.g., 507) to
adjust the heating output. In one implementation, the heating
output of the heating element may be determined based on the power
consumed by the heating element or a portion of the heating
element:
Heating Output=V*I, (4)
where V equals the voltage across the heating element and I equals
the current flowing through the heating element. In such an
implementation, the heating output of the heating element may be
adjusted by varying one or more of the voltage and current supplied
to the heating elements.
[0067] It should be recognized that the steps indicated by blocks
603, 605, 607 may be performed simultaneously or substantially
simultaneously such that when the compressor speed is adjusted, the
heating element is also adjusted simultaneously or substantially
simultaneously. In addition, the initiation of process 600 may be
configured to immediately restart after the prior process loop is
completed.
[0068] The amount of heat output by a heating element is
illustrated by lines 717, 719, 721, and 723 of FIGS. 7A-D,
respectively. The cooling output of the CRAC units, determined, for
example, by Equation 1 or some other equation accounting for the
heating element output and cooling element output, is illustrated
by lines 725, 727, 729, and 731 of FIGS. 7A-D, respectively.
[0069] As is illustrated in FIGS. 7A and 7C, the combined output
725, 729 of the heating element and the cooling elements may be
such that the actual cooling output equals the desired cooling
output of the cooling device for any desired cooling output if the
heating element is fully continuously variable.
[0070] As illustrated in FIG. 7B, the combined output 727 of the
heating element and the cooling element may be such the actual
cooling output is generally closer to the desired cooling output
than the cooling output of the cooling element operating alone. In
the embodiment illustrated by FIG. 7B, the heating and cooling
elements may be configured to operate together so that the combined
output of the heating and cooling elements are closer to the
desired cooling output than the configuration in which neither
element is operated at all or the cooling element is operated
alone. For example, below threshold cooling level 733 in FIG. 7B,
the combined operation of the heating and cooling elements would
produce the total output 735, which is farther away from the
desired cooling output when neither the heating element nor cooling
element is operated below that threshold. Above the threshold 733,
however, one or both of the heating element and cooling element may
be operated so that the combined output is as close to the desired
output as available cooling and heating outputs allow.
[0071] As is illustrated in FIG. 7D, to reduce power consumption of
the cooling and heating elements, in one embodiment of the
invention, if minor cooling fluctuations or deficiencies may not
adversely affect the cooled electronic equipment, the cooling
device may not operate one or both of the cooling element and
heating element when such operation could otherwise produce a
desired total cooling output. For example, below the threshold
value 737, because the electronic equipment may not be generating
much heat and few if any adverse affects are possible at such a low
heat level, neither the heating nor cooling elements may be
operated, as illustrated in FIG. 7D. In one implementation, the
threshold 737 may include five percent below the minimum cooling
capacity of the cooling element alone. In one implementation, the
threshold 737 may include a temperature difference from an ideal
equipment temperature (e.g., five degrees Fahrenheit).
[0072] In another example, a similar principle may be applied at
greater desired cooling capacities, such that the heating element
may not operate until the desired cooling capacity differs from the
actually delivered cooling capacity of the cooling element by some
threshold amount. As illustrated in FIG. 7D, a cooling device may
over-cool the electronic equipment until the difference between the
desired cooling and actual cooling reaches a threshold value 739.
Once the threshold value is reached, however, the heating device
may begin to operate to reduce the difference between the desired
cooling output and the actual cooling output of the cooling device,
as described above. In one implementation, the threshold 739 may
include five percent of the total possible output of the cooling
device. In one implementation, the threshold 739 may include a
temperature difference from an ideal equipment temperature (e.g.,
five degrees Fahrenheit).
[0073] It should be appreciated that process 600 and graphs 701,
703, 705, and 707 are described and illustrated as examples only.
Any combination of heating and cooling output may be generated in
accordance with at least one embodiment of the invention.
Furthermore, any process may be performed to generate such heating
and cooling output.
[0074] Although embodiments of the invention have been described
with respect to 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 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).
[0075] 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.
* * * * *