U.S. patent application number 13/084043 was filed with the patent office on 2011-10-13 for cooling device, cooling system, and auxiliary cooling device for datacenter.
This patent application is currently assigned to FUJIKURA LTD.. Invention is credited to Gerald CABUSAO, Koichi MASHIKO, Masataka MOCHIZUKI, Thang NGUYEN, Randeep SINGH.
Application Number | 20110247348 13/084043 |
Document ID | / |
Family ID | 44759925 |
Filed Date | 2011-10-13 |
United States Patent
Application |
20110247348 |
Kind Code |
A1 |
MASHIKO; Koichi ; et
al. |
October 13, 2011 |
Cooling device, cooling system, and auxiliary cooling device for
datacenter
Abstract
A cooling system for a data center, in which a plurality of
servers having exothermic electronic components is installed in a
housing. The cooling system comprises: a cooling circuit, a main
cooling device to cool cooling medium heated by electronic
components, and an auxiliary cooling device to assist the main
cooling device in cooling the cooling medium.
Inventors: |
MASHIKO; Koichi; (Tokyo,
JP) ; SINGH; Randeep; (Tokyo, JP) ; MOCHIZUKI;
Masataka; (Sakura-shi, JP) ; CABUSAO; Gerald;
(Tokyo, JP) ; NGUYEN; Thang; (Tokyo, JP) |
Assignee: |
FUJIKURA LTD.
Tokyo
JP
|
Family ID: |
44759925 |
Appl. No.: |
13/084043 |
Filed: |
April 11, 2011 |
Current U.S.
Class: |
62/62 ;
62/259.2 |
Current CPC
Class: |
H05K 7/2079 20130101;
F28D 20/021 20130101; F28D 15/04 20130101; F25B 23/006 20130101;
Y02E 60/14 20130101; F25D 16/00 20130101; Y02E 60/145 20130101;
F28D 15/0275 20130101 |
Class at
Publication: |
62/62 ;
62/259.2 |
International
Class: |
F25D 31/00 20060101
F25D031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2010 |
JP |
2010-091680 |
Apr 15, 2010 |
JP |
2010-094108 |
Apr 22, 2010 |
JP |
2010-099071 |
May 27, 2010 |
JP |
2010-121954 |
Feb 28, 2011 |
JP |
2011-41903 |
Feb 28, 2011 |
JP |
2011-41904 |
Claims
1. A cooling system for a data center, in which a plurality of
servers having exothermic electronic components is installed in a
housing, comprising: a circuit, in which a cooling medium is
circulated therethrough; a main cooling device, which is connected
with the electronic components through the circuit, and to which
the cooling medium heated by drawing heat from the electronic
components is returned; and an auxiliary cooling device, which is
arranged on a return pipe of the circuit between the main cooling
device and the electronic components to assist the main cooling
device in cooling the cooling medium.
2. The cooling system for a data center according to claim 1,
wherein: the auxiliary cooling device comprises a tank which stores
the cooling medium therein, and a first plurality of heat pipes
which are adapted to cool or freeze the cooling medium by radiating
heat of the cooling medium to the atmosphere; wherein the first
plurality of heat pipes comprise thermosiphons, in which a volatile
and condensable working fluid is encapsulated air-tightly; wherein
one of end portions of the thermosiphons are immersed into the
cooling medium in the tank to serve as an evaporating portion; and
the other end portion of the thermosiphons are exposed to the
atmosphere to serve as a condensing portion; and, wherein the first
plurality of heat pipes are arranged such that the condensed
working fluid drops only gravitationally to unilaterally restrict
the direction of transport of the heat.
3. The cooling system for a data center according to claim 2,
further comprising: a heat exchanger, which is arranged on the
circuit between the electronic components and the main and
auxiliary cooling devices to exchange the heat of the electronic
components and cold energy of the cooling medium.
4. The cooling system for a data center according to claim 2,
further comprising: a cooling tower, which is connected with the
main cooling device to radiate heat of the main cooling device to
the atmosphere.
5. The cooling system for a data center according to claim 2,
wherein the auxiliary cooling device further comprises a flow
channel letting through the cooling medium supplied to the tank
unilaterally.
6. The cooling system for a data center according to claim 2,
further comprising: a mixing tank.
7. The cooling system for a data center according to claim 6,
wherein: the mixing tank is divided into a plurality of mixing
chambers, and adjoining mixing chambers are connected by a through
hole.
8. The cooling system for a data center according to claim 7,
further comprising: a first switching valve, which switches a route
for feeding the cooling medium from the mixing tank to the
electronic component between a route from said one of the mixing
chamber to the electronic component, and a route from said another
one of the mixing chamber to the electronic component; a first
pump, which is arranged between the first switching valve and the
electronic component to feed the cooling medium to the electronic
component; a second switching valve, which switches a route for
feeding the cooling medium from the mixing tank to the main cooling
device between a route from said one of the mixing chamber to the
main cooling device, and a route from said another one of the
mixing chamber to the main cooling device; a second pump, which is
arranged between the second switching valve and the main cooling
device to feed the cooling medium to the main cooling device; and a
third pump, which is arranged on a route between said one of the
mixing chamber and the auxiliary cooling device to feed the cooling
medium in said one of the mixing chamber to the auxiliary cooling
device.
9. The cooling system for a data center according to claim 2,
further comprising: a first switching valve, which returns the
cooling medium heated by heat of the electronic components
selectively to the main cooling device and the auxiliary cooling
device; and a second switching valve, which supplies the cooling
medium to the electronic component selectively from the main
cooling device and the auxiliary cooling device.
10. The cooling system for a data center according to claim 9,
further comprising: a first pump, which is arranged on the circuit
connecting the electronic component and the heat exchanger to
circulate the cooling medium therethrough; a second pump, which is
arranged on the circuit connecting the heat exchanger and the main
cooling device to circulate the cooling medium therethrough; and a
third pump, which is arranged on the circuit connecting the main
cooling device and the cooling tower to circulate the cooling
medium therethrough.
11. The cooling system for a data center according to claim 2,
wherein the auxiliary cooling device further comprises: a heat
insulating layer, which covers the tank to prevent the tank from
being warmed by an external heat.
12. The cooling system for a data center according to claim 2,
wherein the auxiliary cooling device further comprises: a cold
storage medium, which is sealed in the tank to be frozen by
external cold energy entering into the tank through the
thermosiphon; and a heat exchanging tube, which is arranged around
the evaporating portion of the thermosiphon, and at which the cold
energy of the frozen cold storage medium in the tank is transferred
to the cooling medium flowing therethrough.
13. The cooling system for a data center according to claim 11,
wherein the heat insulating layer comprises: an inner layer formed
of an evacuated panel in which an internal pressure is reduced to
be lower than an atmospheric pressure; and an outer layer formed of
heat insulating porous material.
14. The cooling system for a data center according to claim 12,
wherein: the heat exchanging tube includes a coil heat exchanger
formed by winding a hollow tube around the evaporating portion of
the thermosiphon.
15. The cooling system for a data center according to claim 11,
wherein the auxiliary cooling device further comprises: a soil
layer containing predetermined moisture and covering the tank; and
a second plurality of heat pipes which are buried in the soil layer
at least partially to freeze the moisture in the soil layer by
radiating the heat of the moisture unilaterally to the atmosphere,
under the condition in which a temperature of the moisture in the
soil layer is higher than an external temperature and the external
temperature is lower than a predetermined temperature.
16. The cooling system for a data center according to claim 15,
wherein: said second plurality of heat pipes comprise
thermosiphons, in which a volatile and condensable working fluid is
encapsulated air-tightly; wherein one of end portions of the
thermosiphons are buried in the soil layer to serve as an
evaporating portion; and the other end portion of the thermosiphons
are exposed to the atmosphere to serve as a condensing portion, and
wherein the first plurality of heat pipes are arranged such that
the condensed working fluid drops only gravitationally to
unilaterally restrict the direction of transport of the heat.
17. The cooling system for a data center according to claim 15,
wherein: a thickness of the soil layer is approximately 1
meter.
18. The cooling system for a data center according to claim 12,
wherein: the heat exchanging tube includes a U-shaped heat
exchanger formed by bending a hollow tube into U-shape and arranged
in the vicinity of the evaporating portion of the thermosiphon.
19. The cooling system for a data center according to claim 1,
further comprising: an air conditioner, which is arranged in the
housing to control the temperature in the housing thereby cooling
the server; and an assist heat pipe, which transports heat in the
housing unilaterally to the atmosphere thereby assisting the air
conditioner; and wherein the assist heat pipe includes a
thermosiphon, in which a volatile and condensable working fluid is
encapsulated air-tightly; one of end portions of the thermosiphon
is situated in the housing above the server in a direction of
gravitational force, and the other end portion of the thermosiphon
is exposed to the atmosphere; and, wherein the assist heat pipe is
arranged such that the condensed working fluid drops only
gravitationally to unilaterally restrict the direction of transport
of the heat.
20. The cooling system for a data center according to claim 1,
wherein the auxiliary cooling device is buried in the ground in a
cold region where a freezing index is higher than 400 degree
C.day.
21. A process of cooling a data center, wherein the process
comprises the steps of supplying the cooling medium heated by the
electronic component, and the cooling medium cooled by the main
cooling device or the auxiliary cooling device, to the mixing tank
of the cooling system of claim 6 to regulate the temperature
thereof; and selectively supplying the cooling medium mixed in the
mixing tank to the main cooling device and the auxiliary cooling
device to be cooled, and also to the electronic component.
22. A process of cooling a data center, wherein the process
comprises the steps of supplying the cooling medium heated by the
electronic component to one of the mixing chambers connected with
the electronic component; and supplying the cooling medium cooled
by the main cooling device or the auxiliary cooling device to
another one of the mixing chambers of claim 7 connected with the
main cooling device and the auxiliary cooling device; and gradually
mixing the cooling medium heated by the electronic component, and
the cooling medium cooled by the main cooling device or the
auxiliary cooling device, in the mixing tank while flowing across
the mixing chambers.
23. The cooling system for a data center according to claim 14,
wherein: the material of the heat exchanging tube is selected from
the group consisting of copper, copper alloy, aluminum, aluminum
alloy, and synthetic resin.
24. The cooling system for a data center according to claim 17,
wherein: the material of the soil layer is selected from a group
consisting of sand, loam and clay.
25. The cooling system for a data center according to claim 24,
wherein a moisture content of the soil layer is kept within a range
of 2.5 to 10% when the soil layer is formed of sand, a moisture
content of the soil layer is kept within a range of 10 to 17.5%
when the soil layer is formed of loam, and a moisture content of
the soil layer is kept within a range of 17.5 to 25% when the soil
layer is formed of clay.
Description
[0001] The present invention claims the benefit of Japanese Patent
Applications No. 2010-91680 filed on Apr. 12, 2010, No. 2010-94108
filed on Apr. 15, 2010, No. 2010-99071 filed on Apr. 22, 2010, No.
2010-121954 filed on May 27, 2010, No. 2011-41903 filed on Feb. 28,
2011 and No. 2011-41904 filed on Feb. 28, 2011 with the Japanese
Patent Office, the disclosures of which are incorporated herein by
reference in their entirety.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a cooling device and a
cooling system for cooling a data center comprising a plurality of
computer servers, and in addition, to an auxiliary cooling device
for cooling the data center in case a main cooling device cannot be
used to cool the data center.
[0004] 2. Discussion of the Related Art
[0005] A computer server comprises a plurality of exothermic
electronic components arranged on a printed-circuit board, and
those electronic components produce heat as a result of being
energized to carry out data processing. Therefore, a temperature in
a datacenter in which a plurality of servers is installed is raised
by the heat of the electronic components. The temperature in the
datacenter thus raised is conventionally lowered using an air
conditioner thereby cooling the heated electronic components of the
servers. In addition, the electronic components itself are cooled
directly or indirectly by a refrigerant such as water, brine, etc.
cooled by a chiller unit. However, since the data processing of the
electronic components is carried out ceaselessly, the chiller unit
has to be operated ceaselessly too. Therefore, electric consumption
of the air conditioner, and a load on the chiller unit for cooling
the refrigerant are increased according to an increase in an amount
of the heat generated by the electronic components. As a result, a
running cost of the data center increases. In order to avoid such
an increase in the running cost of the data center, it is necessary
to downsize the cooling system of the data center.
[0006] In addition, a backup cooling system composed mainly of a
chiller unit is used in the prior art for the purpose of cooling
the data center in case the air conditioner or a main chiller unit
is out of order, or in case of a power outage. The backup cooling
system of this kind is configured to prepare cool water by the
chiller unit, and the prepared cool water is reserved in the backup
cooling system to be used for cooling the data center in case of
aforementioned emergency situation. Specifically, the cool water of
5 to 8 degrees is reserved in the backup cooling system in an
amount sufficient to cool the data center for about six hours.
Thus, the conventional backup cooling system has to be large enough
to continuously contain such a large amount of water. In addition
to the above-explained disadvantage, a large electricity cost is
required to operate the chiller unit continuously. Therefore, it is
necessary to downsize the conventional backup cooling system, and
reduce the cost of running the system.
[0007] For example, an energy-saving cold storage comprising an ice
making pit arranged underneath the storage is disclosed in Japanese
Patent Laid-Open No. 60-207877. According to the teachings of
Japanese Patent Laid-Open No. 60-207877, the ice making pit is
configured to freeze water reserved therein in winter time by
dissipating heat of the water to the atmosphere using a heat pipe
penetrating through the storage. Therefore, an inner space of the
storage can be cooled by cold energy of the ice without running
cost.
[0008] Japanese Patent Laid-Open No. 2002-372354 discloses a
cooling system capable of saving on power consumption and cost.
According to the teachings of Japanese Patent Laid-Open No.
2002-372354, a refrigerator is driven during nighttime thereby
storing ice in a storage tank utilizing cheaper nighttime
electricity. The cold energy of the ice thus prepared during the
nighttime is utilized during the daytime by circulating cold water
melted from the ice within a cold water showcase. Further, a coil
is arranged around the cold water showcase and refrigerant is
circulated through the coil. Therefore, the cold water showcase
serves as an evaporator for the refrigerator.
[0009] In addition, Japan Patent Laid-Open No. 11-223449 discloses
a cooling system comprising: a chiller unit for cooling brine to
prepare ice: a heat exchanger for exchanging heat between the
cooling system and the chiller unit; and an ice storage tank.
According to the teachings of Japanese Patent Laid-Open No.
11-223449, the cooling system is connected with both of the heat
exchanger and the chiller unit. The ice in the storage tank can be
used to keep the cooling system at a low temperature in the form of
cool water. Therefore, the cooling system taught by Japanese Patent
Laid-Open No. 11-223449 can be kept at a low temperature not only
by the chiller unit but also by the cold energy of the ice. In
addition, it is also possible to cool down the cooling system using
both of the chiller unit and the ice in the storage tank. According
to the teachings of Japanese Patent Laid-Open No. 11-223449, the
chiller unit is also operated to prepare the ice during the
nighttime utilizing cheaper nighttime electricity.
[0010] Further, Japanese Patent Laid-Open No. 7-4800 discloses a
heat pipe type supercooling ice making equipment comprising: a heat
pipe; a jacket for circulating refrigerant from a refrigerator
arranged on an upper part of the heat pipe; a heater arranged on a
lower part of the heat pipe; a coil-shaped resin tube for letting
water therethrough which is wound around the heat pipe; an ice heat
storage device (i.e., a tank); and a supercooled water destructing
plate to which the water discharged from the tube is dropped.
According to the teachings of Japanese Patent Laid-Open No. 7-4800,
the water is circulated between the tube and the ice heat storage
device while driving the refrigerator using nighttime electricity.
Consequently, the heat pipe is activated as a heat exchanger, and
the water flowing through the tube is supercooled. The water thus
supercooled is discharged from the tube and collide against the
supercooled water destructing plate and is frozen.
[0011] However, according to the cold storage taught by Japanese
Patent Laid-Open No. 60-207877, cold energy of the ice in the ice
making pit may be radiated to the atmosphere through the soil
around the ice making pit when the external temperature is higher
than a coagulation temperature.
[0012] Meanwhile, according to the teachings of Japanese Patent
Laid-Open No. 2002-372354 and No. 11-223449, the chiller unit is
the only cooling means storing the cold energy. Therefore, in case
the chiller unit has some kind of trouble or in case of power
outage, the cooling systems taught by Japanese Patent Laid-Open No.
2002-372354 and No. 11-223449 are unable to perform their cooling
function.
[0013] Also, the ice making equipment taught by Japanese Patent
Laid-Open No. 7-4800 cannot make ice in case the refrigerator is in
trouble or in case of power outage. In addition to the
above-explained disadvantage, according to the teachings of
Japanese Patent Laid-Open No. 7-4800, the cold energy in the ice
heat storage device cannot be transported in case the water therein
is completely frozen.
SUMMARY
[0014] The present invention has been conceived noting
above-mentioned problems, and it is therefore an object of the
present invention to provide a cooling system for cooling a data
center which is capable of reducing a running cost for cooling an
exothermic electronic component of a computer server. In addition,
another object of the present invention is to provide an auxiliary
cooling device for cooling the exothermic electronic component in
case the cooling device is not available to cool the exothermic
electronic component.
[0015] In order to achieve the aforementioned objective, according
to a first example of the present invention, there is provided a
cooling system for a data center, in which a plurality of servers
having exothermic electronic components is installed in a housing,
comprising: a circuit, in which a cooling medium is circulated
therethrough; a main cooling device, which is connected with the
electronic components through the circuit, and to which the cooling
medium heated by drawing heat from the electronic components is
returned; and an auxiliary cooling device, which is arranged on a
return pipe of the circuit between the main cooling device and the
electronic components to assist the main cooling device in cooling
the cooling medium.
[0016] The auxiliary cooling device comprises a tank which stores
the cooling medium therein, and a plurality of heat pipes which is
adapted to cool or freeze the cooling medium by radiating heat of
the cooling medium to the atmosphere. For example, the heat pipe is
a thermosiphon, in which a volatile and condensable working fluid
is encapsulated air-tightly, and a direction to transport the heat
is restricted unilaterally by allowing condensed working fluid to
drop only gravitationally. Specifically, one of end portions of the
thermosiphon is immersed into the cooling medium in the tank to
serve as an evaporating portion, and other end portion of the
thermosiphon is exposed to the atmosphere to serve as a condensing
portion.
[0017] The cooling system according to the first example further
comprises a heat exchanger, which is arranged on the circuit
between the electronic components and the cooling devices to
exchange the heat of the electronic components and cold energy of
the cooling medium.
[0018] The cooling system further comprises a cooling tower, which
is connected with the main cooling device to radiate heat of the
main cooling device to the atmosphere.
[0019] In addition, the auxiliary cooling device further comprises
a flow channel letting through the cooling medium supplied to the
tank unilaterally.
[0020] According to the second example of the present invention,
the cooling system further comprises a mixing tank, to which the
cooling medium heated by the electronic component, and the cooling
medium cooled by the main cooling device or the auxiliary cooling
device, are supplied to regulate the temperature thereof. The
cooling medium mixed in the mixing tank is selectively supplied to
the main cooling device and the auxiliary cooling device to be
cooled, and also used to cool the electronic component.
[0021] The mixing tank is divided into a plurality of mixing
chambers, and the adjoining mixing chambers are connected by a
through hole. Specifically, the cooling medium heated by the
electronic component is supplied to one of the mixing chambers
connected with the electronic component, and the cooling medium
cooled by the main cooling device or the auxiliary cooling device
is supplied to another one of the mixing chambers connected with
the main cooling device and the auxiliary cooling device.
Therefore, the cooling medium heated by the electronic component,
and the cooling medium cooled by the main cooling device or the
auxiliary cooling device are mixed gradually in the mixing tank
while flowing across the mixing chambers.
[0022] According to the second example, the cooling system further
comprises, a first switching valve, which switches a route for
feeding the cooling medium from the mixing tank to the electronic
component between a route from said one of the mixing chamber to
the electronic component, and a route from said another one of the
mixing chamber to the electronic component; a first pump, which is
arranged between the first switching valve and the electronic
component to feed the cooling medium to the electronic component; a
second switching valve, which switches a route for feeding the
cooling medium from the mixing tank to the main cooling device
between a route from said one of the mixing chamber to the main
cooling device, and a route from said another one of the mixing
chamber to the main cooling device; a second pump, which is
arranged between the second switching valve and the main cooling
device to feed the cooling medium to the main cooling device; and a
third pump, which is arranged on a route between said one of the
mixing chamber and the auxiliary cooling device to feed the cooling
medium in said one of the mixing chamber to the auxiliary cooling
device.
[0023] According to the third example of the present invention, the
cooling system of the first example further comprises: a first
switching valve, which returns the cooling medium heated by the
heat from the electronic components selectively to the main cooling
device and the auxiliary cooling device; and a second switching
valve, which supplies the cooling medium to the electronic
component selectively from the main cooling device and the
auxiliary cooling device.
[0024] The cooling system according to the third example further
comprises: a first pump, which is arranged on the circuit
connecting the electronic component and the heat exchanger to
circulate the cooling medium therethrough; a second pump, which is
arranged on the circuit connecting the heat exchanger and the main
cooling device to circulate the cooling medium therethrough; and a
third pump, which is arranged on the circuit connecting the main
cooling device and the cooling tower to circulate the cooling
medium therethrough.
[0025] According to the fourth example, the auxiliary cooling
device further comprises a heat insulating layer, which covers the
tank to prevent the tank from being warmed by an external heat.
[0026] In addition, according to the fourth example, the auxiliary
cooling device further comprises: a cold storage medium, which is
sealed in the tank to be frozen by external cold energy entering
into the tank through the thermosiphon; and a heat exchanging tube,
which is arranged around the evaporating portion of the
thermosiphon, and through which the cold energy of the frozen cold
storage medium in the tank is transferred to the cooling medium
flowing therethrough.
[0027] Specifically, the heat insulating layer comprises: an inner
layer formed of an evacuated panel in which an internal pressure is
reduced to be lower than an atmospheric pressure; and an outer
layer formed of heat insulating porous material.
[0028] The aforementioned heat exchanging tube includes a coil heat
exchanger formed by winding a hollow tube around the evaporating
portion of the thermosiphon; and material of the heat exchanging
tube is selected from the group consisting of copper, copper alloy,
aluminum, aluminum alloy, and synthetic resin.
[0029] According to a fifth example of the present invention, the
auxiliary cooling device further comprises: a soil layer containing
predetermined moisture and covering the tank; and another heat pipe
which is buried in the soil layer at least partially to freeze the
moisture in the soil layer by radiating the heat of the moisture
unilaterally to the atmosphere, under the condition in which a
temperature of the moisture in the soil layer is higher than an
external temperature and the external temperature is lower than a
predetermined temperature.
[0030] The aforementioned another heat pipe is also a thermosiphon,
in which a volatile and condensable working fluid is encapsulated
air-tightly, and a direction to transport the heat is restricted
unilaterally by allowing the condensed working fluid to drop only
gravitationally. Specifically, one of end portions of the
thermosiphon buried in the soil layer serves as an evaporating
portion; and other end portion of the thermosiphon exposed to the
atmosphere serves as a condensing portion.
[0031] Specifically, a thickness of the soil layer is approximately
1 meter, and material of the soil layer is selected from a group
consisting of sand, loam and clay. For example, in case the soil
layer is formed of sand, a moisture content of the soil layer is
kept within a range of 2.5 to 10%, in case the soil layer is formed
of loam, a moisture content of the soil layer is kept within a
range of 10 to 17.5%, and in case the soil layer is formed of clay,
a moisture content of the soil layer is kept within a range of 17.5
to 25%.
[0032] In addition, the heat exchanging tube includes a U-shaped
heat exchanger formed by bending a hollow tube into U-shape and
arranged in the vicinity of the evaporating portion of the
thermosiphon.
[0033] According to the sixth example of the present invention, the
cooling system further comprises: an air conditioner, which is
arranged in the housing to control the temperature in the housing
thereby cooling the server; and an assist heat pipe, which
transports heat in the housing unilaterally to the atmosphere
thereby assisting the air conditioner. The assist heat pipe is also
a thermosiphon, in which a volatile and condensable working fluid
is encapsulated air-tightly, and in which a direction to transport
the heat is restricted unilaterally by allowing the condensed
working fluid to drop only gravitationally. Specifically, one of
end portions of the thermosiphon is situated in the housing above
the server in a direction of gravitational force, and the other end
portion of the thermosiphon is exposed to the atmosphere.
[0034] In addition, the auxiliary cooling device is buried in the
ground in a cold region where a freezing index is higher than 400
degree C.day.
[0035] Thus, according to the cooling device of the first example,
the auxiliary cooling device is arranged on the pipeline returning
the cooling medium from the electronic component to the main
cooling device. Therefore, the cooling medium heated as a result of
cooling the electronic components is cooled prior to reaching the
main cooling device. The cooling medium thus cooled by the
auxiliary cooling device is then supplied to the main cooling
device. As a result, a burden of the main cooling device can be
lightened so that the main cooling device can be downsized and the
running cost thereof can be reduced. In case the temperature of the
cooling medium circulating in the circuit is lowered to a desired
temperature, the main cooling device can be stopped. In addition to
the above-explained advantages, since the auxiliary cooling device
is configured to radiate the heat of the cooling medium using the
heat pipe, maintenance and repair of the auxiliary cooling device
is substantially unnecessary.
[0036] In the auxiliary cooling device, the heat of the cooling
medium in the tank is radiated to the atmosphere through the heat
pipe. As described, the thermosiphon is used as the heat pipe, and
the direction of the thermosiphon to transport the heat is
restricted to one direction by thermal diode characteristics
thereof. Therefore, an external heat cannot enter into the
auxiliary cooling device through the thermosiphon, that is, the
cooling medium will not be warmed by the external heat.
[0037] As described, the cooling system of the present invention
comprises the heat exchanger between the server and the cooling
devices. Therefore, the heat of the electronic component and the
cold energy of the main cooling device can be exchanged in the heat
exchanger so that the cooling medium heated by the electronic
component can be cooled prior to reaching the auxiliary cooling
device.
[0038] Since the main cooling device is connected with the cooling
tower, the heat of the cooling medium returned to the main cooling
device can be radiated to the atmosphere from the cooling
tower.
[0039] As described, according to the second example, the flow
channel for letting through the cooling medium unilaterally is
formed in the auxiliary cooling device. Therefore, the cooling
medium can be cooled by the thermosiphon when flowing through the
auxiliary cooling device.
[0040] According to the second example of the present invention,
the cooling medium heated by the electronic component, and the
cooling medium cooled by the main and the auxiliary cooling devices
are supplied to the mixing tank. Therefore, those cooling mediums
are mixed together in the mixing tank, and as a result, the
temperature of the cooling medium is first neutralized in the
mixing tank. The cooling medium thus neutralized in the mixing tank
can be supplied selectively to the main cooling device and the
auxiliary cooling device to be cooled. For this reason, a burden on
the main cooling device can be lightened and cold energy in the ice
storage device can be prevented from being consumed wastefully.
Moreover, in case the cooling medium can be cooled sufficiently in
the mixing tank, the cooling medium can also be supplied to the
electronic component directly from the mixing chamber. In this
case, the electronic components can be cooled by the cooling medium
cooled only in the mixing tank without running the main cooling
device.
[0041] As described, the mixing tank is divided into a plurality of
mixing chambers, and adjoining chambers are communicated through a
through hole. Specifically, the cooling medium heated by the
electronic component is supplied to one of the mixing chambers
connected with the electronic component, and the cooling medium
cooled by the main cooling device or the auxiliary cooling device
is supplied to another one of the mixing chambers connected with
the main cooling device and the auxiliary cooling device. The
cooling medium supplied to said one of the mixing chamber is
convectively migrated toward said another one of the mixing chamber
through the through holes, and the cooling medium supplied to said
another one of the mixing chamber is convectively migrated toward
said one of the mixing chamber through the through holes.
Therefore, the cooling medium of high temperature and the cooling
medium of low temperature can be mixed stepwise while flowing
across the mixing chambers.
[0042] In addition to the above explained advantages, according to
the cooling system of the second example, the cooling medium can be
supplied to the electronic component selectively from said one of
the mixing chamber and said another one of the mixing chambers
depending on the situation by switching the first switching valve.
Therefore, the electronic component can be prevented from being
cooled insufficiently or excessively. Likewise, the cooling medium
can be supplied to the main cooling device selectively from said
one of the mixing chamber and said another one of the mixing
chambers depending on the situation by switching the second
switching mechanism. Therefore, a burden on the main cooling device
can be lightened.
[0043] According to the cooling system of the third example, the
cooling medium heated by the heat of the electronic component can
be returned selectively to the main cooling device and to the
auxiliary cooling device by switching the first switching
mechanism, and the cooling medium cooled in the main cooling device
and the auxiliary cooling device can be selectively used to cool
the electronic component by switching the second switching
mechanism. Therefore, the cold energy stored in the auxiliary
cooling device can be used to cool the electronic component even if
the main cooling device is not available.
[0044] In addition to the above-explained advantages, according to
the third example, the cooling medium can be forced to circulate by
the first pump in the circuit connecting the electronic component
and the heat exchanger, by the second pump in the circuit
connecting the heat exchanger and the main cooling device, and by
the third pump in the circuit connecting the main cooling device
and the cooling tower.
[0045] According to the fourth example, the tank of the auxiliary
cooling device is covered by the heat insulating layer. Therefore,
the cold energy stored in the auxiliary cooling device can be
prevented from being wasted by the external heat around the tank so
that the cold energy stored therein can be maintained over long
periods.
[0046] Further, according the fourth example, the cold storage
medium is sealed in the tank of the auxiliary cooling device
instead of the cooling medium in a manner not to circulate in the
cooling system, and in a manner to be frozen by the external cold
energy entering into the tank through the thermosiphon. In
addition, the heat exchanging tube is formed around the
thermosiphon. Therefore, the cold energy of the frozen cold storage
medium can be transferred easily to the liquid phase cooling medium
flowing through the heat exchanging tube.
[0047] As described, the heat insulating layer comprises the inner
layer formed of an evacuated panel in which an internal pressure is
reduced to be lower than an atmospheric pressure, and the outer
layer formed of heat insulating porous material. Therefore, heat
insulating properties of the heat insulating layer can be
enhanced.
[0048] Specifically, the heat exchanging tube is formed by winding
the hollow tube around the thermosiphon. That is, a length of a
portion of the heat exchanging tube where the heat exchange between
the frozen cold storage medium and the liquid phase cooling medium
takes place can be elongated. In case of forming the heat
exchanging tube using any of copper, copper alloy, aluminum,
aluminum alloy, heat conductivity thereof can be improved.
Alternatively, In case of forming the heat exchanging tube using
synthetic resin, a cost of the material can be reduced.
[0049] According to the fifth example, the soil layer is frozen by
another heat pipe under the condition in which the temperature of
the moisture contained in the soil layer is higher than the
external temperature, and the external temperature is lower than a
predetermined operating temperature of said another heat pipe. In
this case, therefore, cold storage property of the auxiliary
cooling device can be further enhanced.
[0050] In addition, according to the fifth example, the
thermosiphon is also used as said another heat pipe buried in the
soil layer. Therefore, the external heat cannot enter into the soil
layer through the thermosiphon so that the frozen moisture of the
soil layer can be prevented from being melted by the external
heat.
[0051] Specifically, the soil layer is formed to have a sufficient
thickness to maintain the cold energy in the auxiliary cooling
device all through the year even during summer, e.g., to have
approximately 1 meter thickness. Therefore, a permafrost layer can
be formed around the tank of the auxiliary cooling device by
freezing the soil layer. The cold energy of the permafrost layer
can be utilized to cool the electronic component by arranging the
heat exchanger around the thermosiphon buried in the soil
layer.
[0052] In addition, a configuration of the heat exchanging tube can
be simplified by shaping the heat exchanging tube into a U-shape.
In this case, a length of the heat exchanging tube can be
shortened.
[0053] According to the sixth example, the assist heat pipe is
arranged in the housing to radiate the heat in the housing to the
atmosphere. Therefore, if the air conditioner is arranged in the
housing, a burden of the air conditioner can be lightened. As a
result, an electric consumption and CO.sub.2 emission of the air
conditioner can be reduced. Specifically, one of the end portions
of the assist heat pipe is situated above the servers, and the
other end portion of the assist heat pipe is exposed to the
atmosphere. Therefore, in addition to the above-explained
advantage, the heat of the servers in the housing can be radiated
efficiently to the atmosphere through the assist heat pipe.
[0054] According to the present invention, the auxiliary cooling
device is applied to a data center located in the cold region where
a freezing index is higher than 400 degree C.day. Therefore,
cooling efficiency of the thermosiphon can be improved so that the
cooling medium or the cold storage medium stored in the tank of the
auxiliary cooling device can be frozen.
[0055] Thus, according to the present invention, the auxiliary
cooling device is configured to store the cold energy by radiating
the heat of the cooling medium or the cold storage medium stored
therein to the atmosphere through the heat pipe thereby freezing
the cooling medium or the cold storage medium, under the condition
in which the temperature of the cooling medium or the cold storage
medium is higher than an external temperature and the external
temperature is lower than a predetermined temperature. Therefore,
the auxiliary cooling device is capable of storing the cold energy
therein without consuming electricity, that is, free of cost. In
addition, the auxiliary cooling device is capable of storing the
cold energy without emitting greenhouse gas such as CO.sub.2. This
means that the datacenter using the auxiliary cooling device of the
present invention will not harm the environment. Moreover, the
auxiliary cooling device is configured to store the cold energy by
freezing the cooling medium or the cold storage medium stored
therein. Therefore, in addition to the above-explained advantages,
a capacity of the auxiliary cooling device for storing the cold
energy with respect to an instillation area is larger than a cold
storage device using a liquid phase cooling medium. For this
reason, the auxiliary cooling device can be downsized so that a
construction cost and an installation area thereof can be reduced.
That is, even if a conventional cold storage device has already
been used in a cooling system for a datacenter, the conventional
cold storage device can be replaced easily with the auxiliary
cooling device of the present invention without expanding the
installation area of the cooling system. In addition, a capacity of
the auxiliary cooling device can be increased by merely increasing
the number of tanks without introducing additional air conditioner
or chiller units.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] Features, aspects, and advantages of exemplary embodiments
of the present invention will become better understood with
reference to the following description and accompanying drawings,
which should not be read to limit the invention in any way.
[0057] FIG. 1 is a schematic view showing an exemplary structure of
the cooling system for a datacenter according to the first example
of the present invention;
[0058] FIG. 2 is a schematic view showing an exemplary structure of
the cooling system for a datacenter according to the second example
of the present invention;
[0059] FIG. 3 is a schematic view showing an exemplary structure of
the cooling system for a datacenter according to the third example
of the present invention;
[0060] FIG. 4 is a schematic view showing an exemplary structure of
the cooling system for a datacenter according to the fourth example
of the present invention;
[0061] FIG. 5 is a schematic view showing an installation example
of the cooling system for a datacenter shown in FIG. 4;
[0062] FIG. 6 is a schematic view showing an outlook of the
auxiliary cooling device used in the cooling system shown in FIG.
4;
[0063] FIG. 7 is a sectional view showing a longitudinal section of
the auxiliary cooling device shown in FIG. 6;
[0064] FIG. 8 is a close-up showing the cross section shown in FIG.
7 partially in an enlarged scale;
[0065] FIG. 9 is a schematic view showing an example of the heat
exchanging tube used in the auxiliary cooling device shown in FIG.
6;
[0066] FIG. 10 is a schematic view showing a state in which the
cooling medium around the exchanging tube shown in FIG. 9 is
frozen;
[0067] FIG. 11 is a schematic view showing an exemplary structure
of the cooling system for a datacenter according to the fifth
example of the present invention;
[0068] FIG. 12 is a schematic view showing an outlook of the
auxiliary cooling device used in the cooling system for a data
center shown in FIG. 11;
[0069] FIG. 13 is a sectional view showing a longitudinal section
of the auxiliary cooling device shown in FIG. 12;
[0070] FIG. 14 is a sectional view showing a cross section of the
auxiliary cooling device shown in FIG. 12;
[0071] FIG. 15 is a schematic view showing a configuration of the
thermosiphon type heat pipe arranged in the soil layer;
[0072] FIG. 16 is a schematic view showing a modification of the
auxiliary cooling device shown in FIGS. 12, 13 and 14;
[0073] FIG. 17 is a schematic view showing another modification of
the auxiliary cooling device shown in FIGS. 12, 13 and 14;
[0074] FIG. 18 is a sectional view showing a cross section of the
auxiliary cooling device shown in FIG. 17; and
[0075] FIG. 19 is a schematic view showing an example of arranging
the assist heat pipe of the sixth example in the housing.
DETAILED DESCRIPTION
[0076] Hereinafter, exemplary embodiments of the present invention
will be explained with reference to the accompanying drawings. FIG.
1 is a schematic view showing an exemplary structure of the cooling
system for a datacenter according to the first example. In the
datacenter 1, the plurality of server racks 3 housing the computer
servers is installed in a housing 2. In this example, any kind of
appropriate building can be used as the housing 2. Each of the
servers comprises a plurality of electronic components 8 arranged
on a printed-circuit board, and those electronic components 8
produce heat as a result of being energized to carry out data
processing. For example, the electronic component 8 includes a
central processing unit (abbreviated as CPU), a memory device, an
electric power source and so on. Those electronic components 8 are
contacted individually with a cold plate 9 to exchange the heat
therebetween. Therefore, the electronic components 8 are cooled
directly by the cold plates 9.
[0077] Specifically, the cold plate 9 is a hollow metal plate, and
the cooling medium is allowed to flow through the hollow space. In
order to transfer an external heat to the cooling medium flowing
through the hollow portion of the cold plate 9, the cold plate 9 is
preferably made of material having good heat conductivity.
Therefore, according to the first example, the cold plate 9 is made
of copper or copper alloy. The cold plate 9 is connected with a
heat exchanger 10 through pipelines forming a cooling circuit C1.
Therefore, the heat of the cold plate 9 can be transported to the
heat exchanger 10 by the cooling medium circulating in the cooling
circuit C1.
[0078] The heat exchanger 10 is configured to exchange heat between
high temperature cooling medium flowing therethrough and low
temperature cooling medium flowing therethrough, and for example, a
plate type heat exchanger or the like can be used as the heat
exchanger 10. In order to transport the heat, the cooling medium is
selected from water, water solution containing predetermined amount
of anticorrosion additive, ethylene glycol based or calcium
chloride based brine whose freezing point is lower than 0 degrees
C. (i.e., antifreeze liquid), hydrochlorofluorocarbon such as R-134
or the like.
[0079] The temperature of the cooling medium in the cooling circuit
C1 is raised as a result of drawing the heat from the electronic
component 8, and the cooling medium thus heated by the heat of
electronic component 8 is flown from the cold plate 9 toward the
heat exchanger 10. In the heat exchanger 10, the heat of the
cooling medium in the circuit C1 is transferred to low temperature
cooling medium circulating in an after-mentioned auxiliary cooling
circuit C2. The cooling medium in the cooling circuit C1 thus
cooled in the heat exchanger 10 is returned to the cold plate 9 to
cool the electronic component 8.
[0080] The heat exchanger 10 is also connected with a chiller unit
11 functioning as a main cooling device through pipelines forming
the auxiliary cooling circuit C2. Therefore, the heat of the
cooling medium circulating in the cooling circuit C1 can be
transported from the heat exchanger 10 to the chiller unit 11 by
the cooling medium circulating in the auxiliary cooling circuit C2.
Specifically, the chiller unit 11 is a heat pump comprising: an
internal circuit in which cooling medium such as
hydrochlorofluorocarbon circulates therethrough; a compressor 12
which compress the cooling medium by applying a pressure to the
cooling medium; a condenser 13 which transports heat of the
compressed cooling medium to outside thereby condensing the cooling
medium; an expansion valve 14 which expands the condensed cooling
medium thereby lowering the temperature of the cooling medium; and
an evaporator 15 at which external heat is conducted to the
condensed cooling medium. Thus, the chiller unit 11 is configured
to transport the heat in the form of latent heat by compressing and
expanding the cooling medium circulating therein. For example, a
conventional turbo refrigerator and a screw type chiller using
hydrochlorofluorocarbon as the cooling medium, an absorption
refrigerator using water as the cooling medium and so on can be
used as the chiller unit 11.
[0081] A temperature of the cooling medium circulating in the
auxiliary cooling circuit C2 is raised in the heat exchanger 10 as
a result of receiving the heat of the cooling medium circulating in
the cooling circuit C1. Then, the cooling medium in the auxiliary
cooling circuit C2 thus warmed in the heat exchanger 10 is flown
toward the chiller unit 11 via an after-mentioned auxiliary cooling
device 18, and the heat thereof is absorbed at the evaporator 15 by
the cooling medium circulating in the internal circuit of chiller
unit 11. The cooling medium in the auxiliary circuit C2 thus cooled
in the chiller unit 11 is then returned to the heat exchanger 10,
and the cold energy thereof is transferred to the cooling medium in
the cooling circuit C1. Consequently, the electronic component 8 is
cooled by the cold energy of the cooling medium circulating in the
cooling circuit C1 through the cold plate 9.
[0082] The condenser 13 of the chiller unit 11 is connected with a
cooling tower 16 erected outside of the cooling system through
pipelines forming a radiating circuit C3, and cooling water is
circulated in the radiating circuit C3. Therefore, the heat of the
cooling medium circulating in the internal circuit of the chiller
unit 11 is transmitted to the cooling water circulating in the
radiating circuit C3 at the condenser 13. The heat thus transmitted
to the cooling water in the radiating circuit C3 is radiated from
the cooling tower 16 to the atmosphere by a fan 17.
[0083] In order to cool the cooling medium warmed in the heat
exchanger 10 prior to arriving at the chiller unit 11, the
auxiliary cooling device 18 is arranged in the auxiliary cooling
circuit C2 on the route from the heat exchanger 10 to the chiller
unit 11. For this purpose, the auxiliary cooling device 18 is
provided with: a tank 19 which reserves the cooling medium therein
temporarily; and a plurality of heat pipes 20 which radiate the
heat of the cooling medium in the tank 19 to the atmosphere.
[0084] Specifically, the tank 19 is a watertight hollow container.
Therefore, the water outside of the tank will not penetrate into
the tank 19 and the cooling medium in the tank 19 will not leak
from the tank 19. As described, a role of the tank 19 is to reserve
the cooling medium temporarily thereby cooling the cooling medium
in advance of reaching the chiller unit 11. Therefore, the tank 19
is preferably insulated from the external heat. For this reason,
the tank 19 is formed of low-heat conductive material such as
concrete. In order to protect the tank 19 from the external heat,
it is preferable to bury the tank 19 in the ground.
[0085] In addition, a plurality of flow channels 21 is formed on a
bottom of the tank 19. More specifically, the flow channel 21 is a
grove between ribs 22 for letting through the cooling medium.
Therefore, in the auxiliary cooling device 18, the cooling medium
flowing from the heat exchanger 10 is allowed to flow through the
flow channels 21 unidirectionally toward the chiller unit 11. In
each of the flow channel 21, the heat pipes 20 are erected
substantially vertically at predetermined intervals. Specifically,
one of end portions of the heat pipe 20 immersed into the cooling
medium in the tank 19 serves as an evaporating portion 20a at which
working fluid encapsulated therein is evaporated. The other end
portion of the heat pipe 20 is exposed to the outside of the tank
19 to be contacted with the external air. That is, the other end
portion 20b serves as a condensing portion at which the vaporized
working fluid in the heat pipe 20 is condensed by radiating the
heat of the vaporized working fluid to the atmosphere. For this
purpose, a plurality of radiating fins 23 is arranged on the
condensing portion 20b.
[0086] Specifically, the heat pipe 20 is a thermosiphon comprising
an evacuated hollow container, and volatile and condensable working
fluid contained in the container air-tightly. In order to exchange
internal heat and external cold energy efficiently, the container
of the heat pipe 20 is preferably made of material having good heat
conductivity such as copper. Preferably, the heat pipe 20 is
configured to be activated under the condition where the external
temperature is lower than 10 degrees C. For this purpose, the
working fluid of the heat pipe 20 is selected from ammonia and
hydrochlorofluorocarbon such as R-134 or the like whose boiling
point is lower than 10 degrees C., and 20 to 30 volume percent of
the working fluid is contained in the heat pipe 20.
[0087] Therefore, provided that the external temperature is lower
than 10 degrees C., and the temperature of the cooling medium in
the tank 19 is higher than 10 degrees C., the working fluid is
vaporized in the evaporating portion 20a. The vapor of the working
fluid rises toward the condensing portion 20b where the temperature
and the pressure are lower than those in the evaporating portion
20a, and the heat in the tank 19 thus transported to the condensing
portion 20b by the vaporized working fluid is then radiated to the
atmosphere thorough the fins 23. As a result, the cooling medium in
the tank 19 is cooled and the temperature thereof is lowered. The
vaporized working fluid is condensed again in the condensing
portion 20b and returned gravitationally to the evaporating portion
20a. Thus, a thermal diode characteristic of the heat pipe 20
ensures to transport the heat unilaterally from evaporating portion
20a toward the condensing portion 20b thereby radiating the heat of
the cooling medium in the tank 19 unilaterally to the outside of
the tank 19. Conversely, in case the external temperature is higher
than 10 degrees C., the heat pipe 20 will not be activated. In this
case, therefore, the external temperature is prevented from
entering into the tank 19 so that the temperature of the cooling
medium in the tank 19 will not be raised by the external
temperature.
[0088] Additionally, it is possible to arrange a wick in the
evaporating portion 20a of the heat pipe 20 from a level of the
cooling medium in the tank 19 to a bottom of the heat pipe 20. In
this case, the liquid phase working fluid in the evaporating
portion 20a is soaked up to an upper end of the wick by capillary
action of the wick. Therefore, the portion of the heat pipe 20 in
which the wick is thus arranged is allowed to serve as the
evaporating portion 20a entirely even if a level of the liquid
phase working fluid in the evaporating portion 20a becomes lower
than the level of the cooling medium in the tank 19. However, the
thermal diode characteristics of the heat pipe 20, that is, the
direction to transport the heat will not be changed even if the
wick is thus arranged in the evaporating portion 20a.
[0089] Thus, according to the first example, the heat of the
electronic component 8 is drawn by the cooling medium circulating
in the cooling circuit C1. The heat of the electronic component 8
transmitted to the cooling medium circulating in the cooling
circuit C1 is then transported to the heat exchanger 10, and
transferred to the cooling medium circulating in the auxiliary
cooling circuit C2 cooled by the chiller unit 11. The cooling
medium in the cooling circuit C1 thus cooled in the heat exchanger
10 is returned toward the electronic component 8. Meanwhile, the
cooling medium in the auxiliary cooling circuit C2 warmed in the
heat exchanger 10 by the cooling medium in the cooling circuit C1
is returned to the chiller unit 11 while being cooled by the
auxiliary cooling device 18 on the way.
[0090] Specifically, the heat of the cooling medium in the
auxiliary cooling circuit C2 being returned from the heat exchanger
10 to the chiller unit 11 is dissipated to the atmosphere in
advance through the heat pipes 20 in the auxiliary cooling device
18. That is, the cooling medium in the auxiliary cooling circuit C2
is cooled by the auxiliary cooling device 18 prior to cooling by
the chiller unit 11. Therefore, the temperature of the cooling
medium in the auxiliary cooling circuit C2 returned to the chiller
unit 11 has already been lowered to a certain level so that the
burden on the chiller unit 11 can be lightened, in comparison with
a case in which the cooling medium is returned directly to the
chiller unit 11 without passing through the auxiliary cooling
device 18. For this reason, a running cost of the chiller unit 11
and CO.sub.2 emission from the chiller unit 11 can be reduced, and
in addition, the chiller unit 11 can be downsized.
[0091] When the temperature of the cooling medium being returned
from the heat exchanger 10 to the chiller unit 11 is lowered to a
desired temperature, e.g., below 10 degrees C., the chiller unit 11
can be stopped. In this case, the cooling medium circulating in the
auxiliary cooling circuit C2 can be cooled sufficiently by merely
radiating the heat thereof through the heat pipes 20 in the
auxiliary cooling device 18, and the electronic component 8 can be
cooled by the cooling medium in the cooling circuit C1 cooled by
the cooling medium in the auxiliary cooling circuit C2. In this
case, therefore, the running cost of the chiller unit 11 can be
eliminated and CO.sub.2 will not be emitted from the chiller unit
11. In addition, the auxiliary cooling device 18 is thus configured
to cool the cooling medium without using mechanical devices such as
the condenser 13 and the compressor 12 used in the chiller unit 11.
Therefore, the structure of the auxiliary cooling device 18 is very
simple so that maintenance of the auxiliary cooling device 18 is
substantially unnecessary. Here, in order to circulate the cooling
medium compulsory in the circuits C1, C2 and C3, a pump may be
arranged on each of the circuits C1, C2 and C3. In addition, the
servers can also be connected directly with the auxiliary cooling
unit 18 and the chiller unit 11 without interposing the heat
exchanger 10 therebetween.
[0092] Here will be explained the second example of the present
invention with reference to FIG. 2. According to the second
example, the server racks 3 are also installed in the housing 2 of
the datacenter 1, and the cold plate 9 is contacted with the
electronic component 8. The cold plate 9 is also connected with the
heat exchanger 10 through the pipelines forming a circuit between
the heat exchanger 10 and the electronic component 8, and the
cooling medium is circulated in the circuit. According to the
second example, in order to absorb or to buffer a volume change in
the cooling medium, an expansion tank 24 is arranged on the
pipeline for returning the cooling medium from the cold plate 9 to
the heat exchanger 10. Therefore, the cooling medium expanded by
the heat of the electronic component 8 can be temporarily reserved
in the expansion tank 24. Although not especially shown in FIG. 2,
the expansion tank 24 is preferably connected with the circuit
through an appropriate relief valve. In addition, in order to
circulate the cooling medium compulsory in the circuit, a pump 25
is arranged between the expansion tank 24 and the heat exchanger
10. Here, a conventional pump can be used as the pump 25.
[0093] The heat exchanger 10 is connected with a mixing tank 26
through a pipe line. Specifically, the mixing tank 26 is configured
to regulate the temperature of the cooling medium therein stepwise
by mixing hot cooling medium and cold cooling medium supplied
thereto from both sides. For this purpose, according to the third
example, the mixing tank 26 is divided into six mixing chambers 26a
to 26f. The adjoining mixing chambers are connected via through
holes 28 formed alternately in vertical direction. For example, the
through hole 28 connecting the mixing chambers 26a and 26b is
formed in a lower side of the mixing tank 26, and the through hole
28 connecting the mixing chambers 26b and 26c is formed in an upper
side of the mixing chamber 26.
[0094] Specifically, the mixing chamber 26a is connected with the
heat exchanger 10 through a pipeline, and the cooling medium heated
in the heat exchanger 10 is supplied to the mixing chamber 26a.
Meanwhile, the mixing chamber 26f is connected with the chiller
unit 11 functioning as the main cooling device and with an ice
storage device 27 functioning as the auxiliary cooling device
through pipelines. Therefore, the cooling mediums cooled by the
chiller unit 11 and the ice storage device 27 are supplied to the
mixing chamber 26f. The mixing chamber 26a is also connected with
the ice storage device 27 and with the chiller unit 11 through
pipelines. Therefore, the cooling medium is supplied to the chiller
unit 11 selectively from the mixing chambers 26a and 26f. The
cooling medium cooled in the chiller unit 11 is returned to the
mixing chamber 26f.
[0095] In addition, the mixing chamber 26a is also connected with
the heat exchanger 10 through a pipeline, and the mixing chamber
26f is also connected with the heat exchange 10 through another
pipeline. Therefore, the cooling medium whose temperature is
regulated stepwise in the mixing chambers 26a to 26f is supplied to
the heat exchanger 10 selectively from the mixing chambers 26a and
26f.
[0096] Next, a function of the mixing chamber 26 will be explained
hereinafter. As described, the cooling medium heated in the heat
exchanger 10 is supplied to the mixing chamber 26a, and flows
toward the mixing chamber 26f via the mixing chambers 26b, 26c, 26d
and 26e. Conversely, the cooling mediums cooled by the chiller unit
11 and the ice storage device 27 are supplied to the mixing chamber
26f, and flows toward the mixing chamber 26a via the mixing
chambers 26e, 26d, 26c and 26b. Therefore the cooling medium having
higher temperature supplied to the mixing chamber 26a from the heat
exchanger 10 is mixed with the cooling medium having lower
temperature flowing from the mixing chamber 26f. As a result, the
cooled cooling medium is convectively submerged toward the lower
side of the mixing chamber 26a, and warmed cooling medium is
convectively raised toward the upper side of the mixing chamber
26a. Then, the cooled cooling medium thus migrates to the lower
side of the mixing chamber 26a flows into the adjoining mixing
chamber 26b through the through hole 28 formed in a lower side of a
partition wall between the mixing chambers 26a and 26b. The cooling
medium thus flowing into the mixing chamber 26b from the mixing
chamber 26a is mixed with the cooling medium having lower
temperature flowing into the mixing chamber 26b from the mixing
chamber 26c. As a result, the warmed cooling medium is convectively
raised toward the upper side of the mixing chamber 26b, and the
cooled cooling medium is convectively submerged toward the lower
side of the mixing chamber 26b. Then, the cooled cooling medium
thus migrates to the upper side of the mixing chamber 26b flows
into the adjoining mixing chamber 26c through the through hole 28
formed in an upper side of a partition wall between the mixing
chambers 26b and 26c. Thus, the high temperature cooling medium
supplied to the mixing chamber 26a flows convectively toward the
mixing chamber 26f while being cooled gradually.
[0097] Conversely, the cooling mediums cooled in the ice storage
device 27 and the chiller unit 11 are supplied to the mixing
chamber 26f as described. The cooling medium having lower
temperature supplied to the mixing chamber 26f is mixed with the
cooling medium having higher temperature flowing into the mixing
chamber 26f from the mixing chamber 26e, and the cooling medium
having lower temperature is convectively submerged toward the lower
side of the mixing chamber 26f. Then, the cooling medium migrates
to the lower side of the mixing chamber 26f and flows into the
adjoining mixing chamber 26e through the through the hole 28 formed
in a lower side of a partition wall between the mixing chambers 26f
and 26e. The cooling medium thus flowing into the mixing chamber
26e from the mixing chamber 26f is mixed with the cooling medium
having higher temperature flowing into the mixing chamber 26e from
the mixing chamber 26d. As a result, the warmed cooling medium is
convectively raised toward the upper side of the mixing chamber
26e, and flows into the adjoining mixing chamber 26d through the
through hole 28 formed in an upper side of a partition wall between
the mixing chambers 26e and 26d. Thus, the low temperature cooling
medium supplied to the mixing chamber 26f flows convectively toward
the mixing chamber 26a while being warmed gradually. That is, the
cooling medium in the cooling chamber 26a is at the highest
temperature, and the temperature of the cooling medium is lowered
gradually from the mixing chambers 26b to 26f.
[0098] The cooling medium whose temperature is thus regulated in
the mixing chamber 26a is partially supplied to the ice storage
device 27. For this purpose, a pump 29 is arranged on the pipeline
connecting the mixing chamber 26a with the ice storage device 27.
Specifically, the ice storage device 27 is configured to cool or
freeze the cooling medium supplied thereto from the mixing tank 26
by radiating the heat of the cooling medium to the atmosphere. In
other words, the ice storage device 27 is configured to store the
cold energy by cooling or freezing the cooling medium stored
therein by external cold energy. The cold energy of the ice stored
in the ice storage device 27 is used to cool the cooling medium
supplied thereto from the mixing chamber 26a, and transported to
the mixing chamber 26f by the cooled liquid phase cooling medium.
Therefore, in order to cool the datacenter 1 effectively, the
mixing tank 26 and the ice storage device 27 are preferably
installed in a cold region where a freezing index is higher than
400 degree C.day.
[0099] Specifically, the ice storage device 27 comprises: a tank 30
which reserves the cooling medium supplied from the mixing chamber
26a temporarily; and a heat pipe 31 which cools and freezes the
cooling medium stored in the tank 30 by radiating the heat of the
cooling medium to the atmosphere. The tank 30 is a watertight
hollow container, therefore, the water outside of the tank 30 will
not penetrate into the tank 30 and the cooling medium in the tank
30 will not leak from the tank 30. In addition, the tank 30 is
preferably insulated from the external heat. Therefore, tank 30 is
preferably formed of low-heat conductive material such as concrete,
and buried in the ground.
[0100] The heat pipe 31 is erected substantially vertically in the
tank 30, and one of the end portions of the heat pipe 31 immersed
into the cooling medium in the tank 30 serves as an evaporating
portion 31a at which working fluid encapsulated therein is
evaporated. The other end portion of the heat pipe 31 is exposed to
outside of the tank 30 to be contacted with the atmosphere. That
is, the other end portion 31b serves as a condensing portion at
which the vaporized working fluid in the heat pipe 31 is condensed
by radiating the heat of the vaporized working fluid to the
atmosphere. For this purpose, a plurality of radiating fins 32 are
arranged on the condensing portion 31b.
[0101] As in the first example, a thermosiphon is also used in the
second example as the heat pipe 31. Therefore, a direction of the
heat pipe 31 to transport the heat is restricted to one direction
by the thermal diode characteristics thereof so that the external
heat will not enter into the tank 30 through the heat pipe 31. The
working fluid encapsulated in the heat pipe 31 is also selected
from ammonia and hydrochlorofluorocarbon such as R-134 or the like
whose boiling point is lower than 10 degrees C.
[0102] Therefore, the working fluid in the heat pipe 31 is
vaporized in the evaporating portion 31a under the condition where
the external temperature is lower than 10 degrees C., and vapor of
the working fluid rises toward the condensing portion 31b. The heat
of the cooling medium is thus transported to the condensing portion
31b by the vaporized working fluid in the form of latent heat, and
radiated to the atmosphere through the fins 32. As a result, the
vaporized working fluid is condensed again and returned
gravitationally to the evaporating portion 31a. Thus, the cooling
medium in the ice storage device 27 is cooled by the external cold
energy under the condition where the external temperature is lower
than 10 degrees C., and frozen under the condition where the
external temperature becomes lower than zero. As described, the
vaporized working fluid is condensed in the condensing portion 31b
and returned gravitationally to the evaporating portion 31a.
Therefore, a content of the liquid phase working fluid in the
condensing portion 31b is much smaller than that of the liquid
phase working fluid in the evaporating portion 31a. For this
reason, the external heat will not be transported from the top side
of the heat pipe 31, that is, from the condensing portion 31b to
the evaporating portion 31a even if the external temperature is
higher than 10 degrees C. Thus, the working fluid in the tank 30
can be prevented from being warmed by the external heat.
[0103] As described, the heat exchanger 10 is connected with the
mixing chambers 26a and 26f through the pipelines, and a switching
valve 33 is arranged at a junction of the pipe line connecting the
mixing chambers 26a and 26f, and the pipeline connecting the heat
exchanger 10 and the pipe line connecting the mixing chambers 26a
and 26f. Therefore, the cooling medium cooled in the mixing tank 26
can be supplied to the heat exchanger 10 selectively from the
mixing chambers 26a and 26f. For example, an electromagnetic 3-way
valve activated electrically to switch the flow channel can be used
as the switching valve 33.
[0104] In order to supply the cooling medium from the mixing
chambers 26a and 26f to the heat exchanger 10, and to return the
cooling medium from the heat exchanger 10 to the mixing chamber
26a, a pump 34 is arranged between the heat exchanger 10 and the
switching valve 33. In this example, a conventional feeding pump is
used as the pump 34.
[0105] In addition, although not shown in FIG. 2, the cooling
system of the second example is further provided with a temperature
detecting means adapted to detect the temperatures of the cooling
mediums in the mixing chambers 26a and 26f, and a control means
adapted to control the switching valve 33 and a below-explained
switching valve 35 according to the temperature detected by the
temperature detecting means. Therefore, the switching valve 33 is
activated to switch a supply source of the cooling medium to the
heat exchanger 10 between the mixing chambers 26a and 26f, in
accordance with a signal from the control means representing the
temperatures of the cooling mediums in the mixing chambers 26a and
26f. Specifically, in case the temperature of the cooling medium in
the mixing chamber 26a is higher than a predetermined temperature,
the switching valve 33 allows the cooling medium in the mixing
chamber 26f to be supplied to the heat exchanger 10. Conversely, in
case the temperature of the cooling medium in the mixing chamber
26a is lower than a predetermined temperature, the switching valve
33 allows the cooling medium in the mixing chamber 26a to be
supplied to the heat exchanger 10. Alternatively, in order to
switch the flow channels in the above-described manner to supply
the cooling medium to the heat exchanger 10, a valve configured to
be switched by a motor or the like may also be used as the
switching valve 33 instead of the electromagnetic valve. Thus, the
switching valve 33 serves as the first switching valve of the
present invention.
[0106] As described, the chiller unit 11 is also connected with the
mixing chambers 26a and 26f through the pipelines, and a switching
valve 35 is arranged at a junction of the pipe line connecting the
mixing chambers 26a and 26f, and the pipeline connecting the
chiller unit 11. Therefore, the cooling medium in the mixing tank
26 can also be supplied to the chiller unit 11 selectively from the
mixing chambers 26a and 26f, and the cooling medium cooled in the
chiller unit 11 is returned to the mixing chamber 26f. Here, the
structure of the switching valve 35 is identical to that of the
switching valve 33. Therefore, in case the temperature of the
cooling medium in the mixing chamber 26f is higher than a
predetermined temperature, the switching valve 35 is switched by
the control means in a manner to allow the cooling medium in the
mixing chamber 26f to be supplied to the chiller unit 11.
Conversely, in case the temperature of the cooling medium in the
mixing chamber 26f is lower than a predetermined temperature, the
switching valve 35 is switched by the control means in a manner to
allow the cooling medium in the mixing chamber 26a to be supplied
to the chiller unit 11. Thus, the switching valve 35 serves as the
second switching valve of the present invention.
[0107] In order to supply the cooling medium to the chiller unit 11
from the mixing chambers 26a and 26f, and to return the cooling
medium from the chiller unit 11 to the mixing chamber 26f, a pump
36 is arranged between the switching valve 35 and the chiller unit
11. Here, a conventional pump is also used to serve as the pump
36.
[0108] As in the first example, the chiller unit 11 is also
connected with the cooling tower 16 erected outside of the cooling
system through pipelines forming a circuit, and in order to
circulate cooling water in the circuit, a pump 37 is arranged on
the pipeline for feeding the cooling water from the chiller unit 11
to the cooling tower 16. Therefore, the heat of the chiller unit 11
is transported to the cooling tower 16 by the cooling water, and
radiated to the atmosphere from the cooling tower 16 by the fan
17.
[0109] Thus, according to the second example of the present
invention, the heat of the electronic component 8 is transported to
the heat exchanger 10 by the cooling medium circulating in the
circuit connecting the cold plate 9 and the heat exchanger 10. The
heat thus transported to the heat exchanger 10 is transferred to
the cooling medium supplied to the heat exchanger 10 from the
mixing chamber 26a or 26f which is cooled by the ice storage device
27 or by the chiller unit 11. The cooling medium warmed in the heat
exchanger 10 is returned to the mixing chamber 26a of the mixing
tank 26, and gradually cooled in the mixing tank 26 while flowing
across the mixing chambers 26a to 26f to be mixed convectively with
the cooling medium flowing from the mixing chamber 26f which is
cooled by the ice storage device 27 or the chiller unit 11. Then,
the cooling medium whose temperature is thus neutralized in the
mixing tank 26 is supplied again to the ice storage device 27 and
to the chiller unit 11. Therefore, according to the second example,
the cold energy in the ice storage device 27 will not be wasted
excessively, that is, the ice stored in the ice storage device 27
will not be melted excessively. In addition to the above-explained
advantage, the burden of the chiller unit 11 can be lightened so
that the running cost of the chiller unit 11 and CO.sub.2 emission
can be reduced. Conversely, according to the cooling system of the
second example, it is also possible to warm the cooling medium in
the mixing tank 26 in advance, and supply the warmed cooling medium
to the heat exchanger 10. In this case, the electronic component 8
can be prevented from being cooled excessively.
[0110] That is, according to the cooling system of the second
example, temperature of the cooling medium to be supplied to the
heat exchanger 10, the chiller unit 11 and the ice storage device
27 can be optimized in the mixing tank 26 before supplied to those
elements. Therefore, thermal efficiency of the cooling system can
be improved. In addition, the temperature of the cooling medium to
be supplied to the heat exchanger 10, the chiller unit 11 and the
ice storage device 27 from the mixing tank 26 can be adjusted more
finely by changing a number of the mixing chambers in the mixing
tank 26. Further, according to the second example of the present
invention, the electronic component 8 can be cooled only by the ice
storage device 27 even if the chiller unit 27 is in trouble or
electric power supply to the chiller unit 11 is interrupted.
[0111] Next, the third example of the present invention will be
explained hereinafter with reference to FIG. 3. Specifically, the
third example of the present invention relates to an auxiliary
cooling device, which is configured to cool the datacenter 1 in
case the chiller unit 11 functioning as the main cooling device is
in trouble due to electric power outage or the like.
[0112] According to the third example, the server racks 3 are also
installed in the container 2 of the datacenter 1. The cold plate 9
is also contacted with the electronic component 8 and connected
with the heat exchanger 10 through the pipelines forming a circuit,
and the pump 25 is arranged on the pipeline for returning the
cooling medium from the cold plate 9 to the heat exchanger 10.
Therefore, the cooling medium can be circulated in the circuit
connecting the cold plate 9 and the heat exchanger 10.
[0113] According to the third example, the heat exchanger 10 is
connected with the evaporator 15 of the chiller unit 11 thorough
pipelines forming a circuit, and in order to circulate the cooling
medium in the circuit, a pump 38 is arranged on the pipeline for
supplying the cooling medium from the chiller unit 11 to the heat
exchanger 10. Therefore, the heat of the electronic component 8 is
transferred to the cold plate 9, and the heat transferred to the
cold plate 9 is transported to the heat exchanger 10 by the cooling
medium. The heat of the cooling medium thus transported to the heat
exchanger 10 from the cold plate 9 is then transferred to the
cooling medium having lower temperature supplied to the heat
exchanger 10 from the chiller unit 11. As a result, the electronic
component 8 is cooled by the cold plate 9.
[0114] Meanwhile, the condenser 13 of the chiller unit 11 is
connected with the cooling tower 16 through pipelines forming a
circuit, and in order to circulate cooling water in the circuit, a
pump 37 is arranged on the pipeline for supplying the cooling
medium from the condenser 13 to the cooling tower 16. The heat of
the cooling medium warmed in the condenser 13 is transported to the
cooling tower 16, and radiated to the atmosphere by the fan 17.
[0115] In the circuit connecting the heat exchanger 10 and the
chiller unit 11, a switching valve 39 is arranged at a junction of
the pipeline for supplying the cooling medium from the heat
exchanger 10 to the evaporator 15 and a pipeline for supplying the
cooling medium from said pipeline to an ice storage device 41
functioning as an auxiliary cooling device. In addition, a
switching valve 40 is arranged at a junction of the pipeline for
supplying the cooling medium from the evaporator 15 to the heat
exchanger 10 and a pipeline for supplying the cooling medium from
the ice storage device 41 to said pipeline. Therefore, according to
the third example, the ice storage device 41 can be used as the
cold source for cooling the datacenter 1 instead of the chiller
unit 11, in case the chiller unit 11 has some kind of trouble.
[0116] Thus, the cooling medium warmed in the heat exchanger 10 is
allowed to flow selectively to the chiller unit 11 and to the ice
storage device 41 by switching the switching valve 39. Likewise,
the cooling medium cooled in the chiller unit 11 is allowed to flow
selectively to the heat exchanger 10 and to the ice storage device
41 by switching the switching valve 40.
[0117] Although not especially shown in FIG. 3, according to the
third example, the cooling system is provided with: a detecting
means adapted to detect a change in the temperature of the
datacenter 1 and to detect a trouble in the chiller unit 11; and a
control means adapted to switch the switching valves 39 and 40 on
the basis of a detection signal from the detecting means.
Therefore, in case the temperature in the datacenter 1 detected by
the detecting means is higher than a predetermined temperature, or
in case a trouble in the chiller unit 11 is detected by the
detecting means, the switching valve 39 is switched by the control
means to allow the cooling medium in the heat exchanger 10 to flow
toward the ice storage device 41, and the switching valve 40 is
switched by the control means to allow the cooling medium in the
ice storage device 41 to flow toward the heat exchanger 10. As
described, an electromagnetic valve can be used as the switching
valves 39 and 40. According to the third example, since the
aforementioned pump 38 is arranged between the switching valve 40
and the heat exchanger 10, the cooling medium can be circulated
among the heat exchanger 10, the chiller unit 11 and the ice
storage device 41 without arranging additional pumps.
[0118] As the examples previously explained, the ice storage device
41 comprises: a tank 42 which reserves the cooling medium therein;
and a plurality of heat pipes 43. In order to insulate the cooling
medium stored in the ice storage device 41, tank 42 is preferably
formed of low-heat conductive material such as concrete.
[0119] According to the third example, a thermosiphon is also used
as the heat pipe 43. Therefore, a direction of the heat pipe 43 to
transport the heat is restricted to one direction, and the external
heat will not enter into the tank 41 through the heat pipe 43.
Also, the working fluid encapsulated in the heat pipe 43 is
selected from ammonia and hydrochlorofluorocarbon such as R-134 or
the like whose boiling point is lower than 10 degrees C., and 20 to
30 volume percent of the working fluid is contained in the heat
pipe 43.
[0120] The heat pipe 43 is erected substantially vertically in the
tank 42, and one of the end portions of the heat pipe 43 immersed
into the cooling medium in the tank 42 serves as an evaporating
portion 43a at which working fluid encapsulated therein is heated
to be vaporized. The other end portion of the heat pipe 43 is
exposed to outside of the tank 42 to be contacted with the
atmosphere. That is, the other end portion serves as a condensing
portion 43b at which the vaporized working fluid in the heat pipe
43 is condensed by radiating the heat of the vaporized working
fluid to the atmosphere. For this purpose, a plurality of radiating
fins 44 are arranged on the condensing portion 43b. The working
fluid thus condensed in the condensing portion 43b is
gravitationally returned to the evaporating portion 43a. In order
to freeze the cooling medium stored in the tank 42 efficiently, the
ice storage device 41 is preferably installed in a cold region
where a freezing index is higher than 400 degree C.day.
[0121] In case the temperature of the cooling medium in the ice
storage device 41 is higher than the external temperature, and the
external temperature becomes lower than a predetermined operating
temperature of the heat pipe 43, the heat of the cooling medium in
the tank 42 is transported in the heat pipe 43 from the evaporating
portion 43a to the condensing portion 43b, and radiated to the
atmosphere from the fins 44. As a result, the cooling medium in the
tank 42 is cooled to store the cold energy, and in case the
external temperature further drops to below freezing point, the
cooling medium in the ice storage device 41 is frozen. Conversely,
even in case the external temperature becomes higher than the
temperature of the cooling medium in the tank 42, the external heat
will not enter into the ice storage device 41 through the heat pipe
43 so that the cooling medium can be prevented from being wasted by
the external air.
[0122] Thus, according to the third example of the present
invention, the cold energy can be stored in the ice storage device
41 utilizing the external cold energy without using electricity.
That is, the ice storage device 41 can be operated without running
cost and without emitting CO.sub.2 gas. Moreover, the cold energy
is stored in the ice storage device 41 in the form of ice.
Therefore, the ice storage device 41 can be downsized in comparison
with a case of storing the cold energy by merely cooling liquid
phase cooling medium so that a construction cost thereof can be
reduced. In addition to the above-explained advantages, the cold
energy stored in the ice storage device 41 can be supplied to the
heat exchanger 10 to cool the heated cooling medium returned to the
heat exchanger 10 from the cold plate 9, in case electric power
supply to the chiller unit 11 is interrupted, or in case a failure
occurs in the chiller unit 11. Thus, the ice storage device 41
serves as the auxiliary cooling device of the present
invention.
[0123] Next, here will be explained a fourth example of the present
invention with reference to FIGS. 4 to 10. The fourth example is a
modified example of the auxiliary cooling device used in the third
example. Therefore, detailed explanation for the elements in common
with the previously explained example is omitted by allotting
common reference numerals. FIG. 4 is a schematic view showing an
entire structure of the cooling system for a datacenter using the
modified auxiliary cooling device according to the fourth example.
As shown in FIG. 4, in the fourth example, the heat exchange 10 is
not interposed between the data center 1 and the chiller unit 11
unlike the third example. However, it is possible to interpose the
heat exchanger 10 between the data center 1 and the chiller unit 11
according to need.
[0124] Specifically, in the fourth example, the cold plate 9 is
connected with the chiller unit 11 through a feeding pipe for
supplying the cooling medium from the chiller unit 11 to the cold
plate 9, and the switching valve 39 is arranged on the feeding
pipe. Therefore, the cooling medium cooled by the chiller unit 11
is supplied to the cold plate 9 via the switching valve 39. The
cold plate 9 is also connected with the chiller unit 11 through a
returning pipe for returning the cooling medium from the cold plate
9 to the chiller unit 11, and the switching valve 40 is arranged on
the returning pipe. Therefore, heat of the electric component 8
transferred to the cold plate 9 is transported to the chiller unit
11 by the cooling medium through the returning pipe via the
switching valve 40.
[0125] In addition, another feeding pipe of the cooling medium is
also extended from the ice storage device 41 and merged with the
feeding pipe extending from the chiller unit 11 at the switching
valve 39. Meanwhile, the returning pipe extending from the cold
plate 9 is divided at the switching valve 40 to be also connected
with the ice storage device 41. Therefore, it is possible to form a
circuit connecting the cold plate 9 and the chiller unit 11, and a
circuit connecting the cold plate 9 and the ice storage device 41
alternately by switching the switching valves 39 and 40.
[0126] In order to force the cooling medium to circulate in each of
the circuits, that is, among the cold plate 9, the chiller unit 11
and the ice storage device 41, the pump 25 is arranged between the
switching valve 39 and the cold plate 9.
[0127] Thus, according the fourth example, the cooling medium can
be circulated alternately in the circuit connecting the cold plate
9 and the chiller unit 11, and in the circuit connecting the cold
plate 9 and the ice storage device 41 by switching the switching
valves 39 and 40 by the control means. Therefore, the cooling
medium heated by the heat of the electronic component 8 in the cold
plate 9 can be returned selectively to the chiller unit 11 and the
ice storage device 41, and the cooling medium cooled in the chiller
unit 11 or the ice storage device 41 can be supplied to the cold
plate 9 selectively depending on the temperature in the data center
1 or depending on an operating condition of the chiller unit
11.
[0128] As shown in FIG. 5, in order to insulate the ice storage
device 41 from the external heat, the ice storage device 41
according to the fourth example is buried in the ground where the
temperature change is smaller than that above the ground, and the
ice storage device 41 is surrounded by a heat insulating layer 45
below the ground, which in turn is surrounded by a waterproof layer
46. FIG. 6 is a schematic view showing an outlook of the ice
storage device 41 of the fourth example, and FIG. 7 is a sectional
view thereof. As shown in FIG. 7, according to the fourth example,
the ice storage device 41 comprises: cold storage medium to be
frozen by the external cold energy; the tank 42 which holds cold
storage medium therein; a heat insulating layer 45 which insulate
the tank 42 from the external heat; a waterproof layer 46 which
prevent external water from penetrating into the tank 42; the
plurality of heat pipes 43 which radiates the heat of cold storage
medium reserved in the tank 42 to the atmosphere, and a coil shaped
heat exchanging tube 49 is wrapped around the evaporating portion
43a of the heat pipe 43. A shape of the tank 42 should not be
limited to a specific shape. However, in case of forming the tank
42 into a cylindrical shape as shown in FIG. 6, a surface area of
the tank 42 can be reduced in comparison with a case of forming the
tank 42 into a cuboid shape having a same capacity.
[0129] FIG. 8 is a close-up showing the cross section of the ice
storage device 41 of the fourth example partially in an enlarged
scale. As shown in FIG. 8, the heat insulating layer 45 comprises
an inner layer 47 formed of a hollow plate; and an outer layer 48
formed of porous material. Specifically, a conventional hollow
vacuum panel in which an internal pressure thereof is lower than an
atmospheric pressure can be used as the inner layer 47, and the
outer layer 48 can be formed of expanded polyurethane, expanded
polystyrene, glass wool etc.
[0130] As described, in order to prevent the external water from
penetrating into the tank 42, the waterproof layer 46 is formed
around the outer layer 48. For example, a waterproof sheet formed
of synthetic resin can be used as the waterproof layer 46.
[0131] An example of a coil shaped heat exchanging tube 49 adapted
to transport the cold energy from the cold storage medium in the
tank 42 is shown in FIG. 9. Specifically, the heat exchanging tube
49 is a hollow tube wrapped spirally around the evaporating portion
43a of the heat pipe 43, and the liquid phase cooling medium is
allowed to flow therethrough. In order to facilitate heat exchange
between the heat of the liquid phase cooling medium flowing through
the heat exchanging tube 49 and the cold energy of the cold storage
medium in the tank 42, material of the heat exchanger 49 is
selected from copper, copper alloy, aluminum, aluminum alloy and so
on. A length of the heat exchanging tube 49 can be adjusted
according to a required amount of the cold energy for cooling the
datacenter 1 to a desired temperature, in other words, according to
an amount of the heat to be exchanged between the cooling medium
and the cold storage medium thorough the heat exchanging tube 49. A
length of the heat exchanging tube 49 required in the ice storage
device 41 can be experimentally found in advance. In addition, in
order to reduce a cost of the material, the heat exchanging tube 49
may also formed of synthetic resin. In this case, heat conductivity
of the heat exchanging tube 49 has to be degraded, however, such
disadvantage can be avoided by elongating the length of the heat
exchanging tube 49.
[0132] In case the switching valve 39 and 40 are switched in a
manner to connect the cold plate 9 and the ice storage device 41,
the cooling medium heated as a result of drawing the heat of the
electronic component 8 in the cold plate 9 is returned to the ice
storage device 41 through the aforementioned returning pipe. The
cooling medium entering into the heat exchanging tube 49 flows from
an upper side of the heat exchanging tube 49 toward a lower side of
the heat exchanging tube 49 while transferring the heat thereof to
the cold storage medium in the tank 42. As a result, the liquid
phase cooling medium flowing through the heat exchanging tube 49 is
cooled by the cold energy of the cold storage medium in the tank
42, and then supplied to the cold plate 9.
[0133] In case the external temperature drops to below the freeing
point, the cold storage medium in the tank 42 is frozen by the
external cold energy entering into the tank 42 through the heat
pipes 43. In this case, first the cold storage medium around a
surface of the evaporating portion 43a starts to be frozen as
illustrated by a dotted line in FIG. 10. Then, the cold storage
medium around the heat exchanging tube 49 is frozen, and eventually
the cold storage medium in the tank 42 is frozen entirely. The
external cold energy is thus stored in the tank 42 in the form of
ice.
[0134] Specifically, in case the detecting means detects that the
temperature in the datacenter 1 is higher than a predetermined
temperature, or that the chiller unit 11 cannot be operated, the
switching valves 39 and 40 are switched by the control means in a
manner to switch a cold energy source used to cool the datacenter 1
from the chiller unit 11 to the ice storage device 41. In this
case, the cooling medium heated by the electronic component 8 in
the cold plate 9 is returned to the heat exchanging tube 49 in the
ice storage device 41 through the returning pipe. As a result, the
heat of the cooling medium flowing through the heat exchanging tube
49 is transferred to the frozen cold storage medium in the tank 42,
and the temperature of the cooling medium is lowered while melting
the frozen cold storage medium. The cooling medium thus cooled in
the ice storage device 41 is then supplied to the cold plate 9
thorough the feeding pipe thereby cooling the electronic component
8.
[0135] Thus, according to the fourth example of the present
invention, the cold energy of the cold storage medium held in the
ice storage device 41 can be transported easily by the liquid phase
cooling medium flowing through the heat exchanging tube 49, even
when the cold storage medium is frozen. In addition, the ice
storage device 41 of the fourth example is buried in the ground,
and covered by the heat insulating layer 45 and the waterproof
layer 46. Therefore, the cold energy stored in the ice storage
device 41 can be prevented from being wasted by the external heat,
and the external water will not penetrating into the tank 42.
[0136] Moreover, the ice storage device 41 functioning as the
auxiliary cooling device of the fourth example is configured to
store the cold energy by freezing the cold storage medium stored
therein only using the external cold energy. Therefore, in addition
to the above-explained advantages, a layout of the cooling system
for the datacenter can be altered flexibly and more easily in
comparison with a cooling system for the datacenter using a
conventional chiller unit adapted to cool the cooling medium
electrically. For example, even in the case where the number of
computer servers is increased and larger output of the cold energy
is therefore required, the output of the ice storage device 41 can
be easily increased by merely increasing the number of heat pipes
43. In this case, the output of the ice storage device 41 can be
increased without expanding an installation area of the ice storage
device 41. Alternatively, it is also possible to introduce
additional ice storage devices 41 easily according to the required
cold energy. Further, the conventional chiller unit used as the
auxiliary cooling device in the conventional cooling system can be
replaced easily by the cold storage device 41 of the present
invention.
[0137] Next, here will be explained a fifth example of the present
invention with reference to FIGS. 11 to 15. The fifth example is
another modified example of the auxiliary cooling device used in
the third example. That is, a relation of connection of the
elements constituting the cooling system is identical to those of
the third and the fourth example shown in FIGS. 3 and 4. Therefore,
detailed explanation for the elements in common with the previously
explained example is omitted by allotting common reference
numerals.
[0138] The ice storage device 41 of the fifth example is preferably
used as the auxiliary cooling device for the datacenter whose
electrical power consumption is approximately 200 kWh. For this
purpose, according to the fifth example, the ice storage device 41
is also buried in the ground, and in order to insulate the ice
storage device 41 more effectively from the external heat thereby
retaining the cold energy therein more efficiently, the ice storage
device 41 of the fifth example is further provided with a soil
layer 52 covering the tank 42.
[0139] As shown in FIG. 12, the ice storage device 41 of the sixth
example is also shaped into a cylindrical shape, and a soil layer
52 is formed around the ice storage device 41. FIG. 13 is a
sectional view showing a cross section of the ice storage device 41
shown in FIG. 12. Specifically, as shown in FIG. 13, a maintenance
room 50 is formed around the tank 42 of the ice storage device 41.
The soil layer 52 is held by a bottomed cylindrical wooden support
53. In order to retain the soil and the water in the soil layer 52,
the waterproof layer 46 is interposed between the soil layer 52 and
the wooden support 53. In order to radiate the heat in the soil
layer 52, according to the fifth example, a plurality of another
heat pipes 54 is buried in the soil layer 52 substantially
vertically at predetermined intervals. Specifically, a thermosiphon
is also used as the heat pipe 54, therefore, a direction of the
heat pipe 54 is restricted to one direction by a thermal diode
characteristics thereof. That is, the external heat will not enter
into the soil layer 52 through the heat pipes 54. As shown in FIG.
14, an entrance 51 is formed in the maintenance room 50 so that a
worker is allowed to enter into the maintenance room 50. In
addition, the soil layer 52 is formed around the maintenance room
50, and underneath the maintenance room 50 and the tank 42.
Specifically, the soil layer 52 contains 5 to 20 percent of
moisture, and a thickness thereof is approximately 1 meter.
Further, according to the fifth example, the aforementioned heat
insulating layer 45 is formed around the wooden support 53 and
underneath the bottom of the wooden support 53. Additionally, as
shown in FIG. 14, the ice storage device 41 is covered with a
shield 57.
[0140] As shown in FIG. 15, a portion of the heat pipe 54 buried in
the soil layer 52 serves as an evaporating portion 54a, and other
end portion of the heat pipe 54 is exposed to outside of the soil
layer 52 to be contacted with the atmosphere serves as a condensing
portion 54b. In order to radiate the heat of the soil layer 52 to
the atmosphere from the condensing portion 54b, a plurality of fins
55 are arranged on the condensing portion 54b. Remaining structures
of the heat pipe 54 are identical to those of the aforementioned
heat pipe 43. Therefore, a detailed explanation for the structure
and function of the heat pipe 54 in common with those of the heat
pipe 43 will be omitted. However, in order to prevent a corrosion
of the heat pipe 54, the heat pipe 54 may be made of
corrosive-resistant material such as stainless. In addition, in
order to radiate the heat in the bottom part of the soil layer 52
to the atmosphere, as shown in FIG. 15, the evaporating portion 54a
of the heat pipe 54 is bent at a vicinity of the bottom of the
maintenance room 50 toward the center of the tank 42. Here, in
order to gravitationally return the working fluid to the end of the
evaporating portion 54a, the bent portion of evaporating portion
54a is preferably tilted at approximately 5 degrees.
[0141] In the fifth example, sand, loam and clay can be used as a
material of the soil layer 52, and moisture content of those
materials are 2.5 to 10 percent, 10 to 17.5 percent, and 17.5 to 25
percent, respectively. Therefore, in case of forming the soil layer
52 mainly using sand, it is preferably to keep the moisture content
of the soil layer 52 within a range of 2.5 to 10 percent.
Consequently, the soil layer 52 can be frozen and strength of the
soil layer 52 can be enhanced by radiating the heat thereof to the
atmosphere through the heat pipes 54. Likewise, in case of forming
the soil layer 52 using loam or clay, the moisture content thereof
are preferably kept to the above-mentioned ranges respectively.
[0142] Next, here will be explained a function of the ice storage
device 41 according to the fifth example. As in the previously
explained examples, in case the temperature of the cold storage
medium in the ice storage device 41 becomes higher than the
external temperature, and the external temperature becomes lower
than a predetermined temperature, the working fluid in the
evaporating portion 43a of the heat pipe 43 is vaporized by the
heat of the cold storage medium stored in the tank 42, and the heat
of the cold storage medium is transported to the condensing portion
43b in the form of the latent heat of the working fluid. The heat
of the cold storage medium thus transported to the condensing
portion 43b is radiated to the atmosphere through the fins 44, and
the condensed working fluid is returned gravitationally to the
evaporating portion 43a. As a result, the cold storage medium in
the tank 42 is cooled. In this situation, in case the external
temperature further drops to below freezing point, the cooling
medium in the ice storage device 41 is frozen by the same principle
explained in the fourth example.
[0143] Likewise, in case the temperature of the soil layer 52
becomes higher than the external temperature, and the external
temperature becomes lower than a predetermined operating
temperature of the heat pipe 54, the working fluid in the
evaporating portion 54a of the heat pipe 54 is vaporized by the
heat of the soil layer 52, and the heat of the soil layer 52 is
transported to the condensing portion 54b by the vaporized working
fluid in the form of the latent heat. The heat of the soil layer 52
thus transported to the condensing portion 54b is radiated to the
atmosphere through the fins 55. Therefore, working fluid is
condensed again in the condensing portion 54b, and returned
gravitationally to the evaporating portion 54a. As a result, the
soil layer 52 is cooled to store the cold energy therein. Also, in
case the external temperature further drops to below the freezing
point, the soil layer 52 is further cooled and frozen. As a result,
the soil layer 52 becomes a permafrost layer. Conversely, since the
thermosiphon is used as the heat pipe 54, the heat pipe 54 will not
transport the heat in case the temperature of the soil layer 52
becomes lower than the external temperature, and the external
temperature becomes higher than a predetermined temperature.
[0144] Thus, the ice storage device 41 of the fifth example is
further provided with the soil layer 52 having approximately 1
meter thickness, and the plurality of heat pipes 54 are buried
therein. In addition, the soil layer 52 is covered by the heat
insulating layer 45, and the ice storage device 41 is installed in
a cold region where a freezing index is higher than 400 degree
C.day. Therefore, in addition to the advantages achieved by the ice
storage device 41 according to the third and the fourth examples,
according to the fifth example, the soil layer 52 frozen by the
heat pipes 54 can be kept to be frozen throughout the year. That
is, the cold energy stored in the tank 42 by freezing the cold
storage medium held therein can also be retained throughout the
year by the soil layer 52 as a permafrost layer. The cold energy
thus stored in the ice storage device 41 can be used to cool the
datacenter 1 anytime when the chiller unit 11 is in trouble.
[0145] Next, here will be explained a modified example of the ice
storage device 41 of the fifth example with reference to FIGS. 16
to 18. The modified ice storage device 41 of the fifth example is
to be used as the auxiliary cooling device for the datacenter whose
electrical power consumption is smaller than 200 kWh. Therefore,
according to the modified example of the fifth example, the tank 42
is relatively smaller than that used in the previously explained
ice storage device 41, and as shown in FIG. 16, the ice storage
device 41 is covered with a shield 57. In addition, a U-shaped heat
exchanging tube 56 is used instead of the coil-shaped heat
exchanging tube 49.
[0146] Specifically, as shown in FIG. 16, most of the modified ice
storage device 41 of the fifth example is buried in the ground, and
the portion of the ice storage device 41 thus buried is covered
with the shield 57. A clearance between the soil layer 52 and the
shield 57 is filled with another soil. An upper portion of the ice
storage device 41 exposed above the ground level is covered with a
lid 58. In order to insulate the portion of the ice storage device
thus exposed, the lid 58 is preferably made of heat insulating
material such as concrete. The heat exchanging tube 56 is a hollow
tube made of heat conductive material such as copper, copper alloy,
aluminum, aluminum alloy and so on, and the liquid phase cooling
medium flowing from the cold plate 9 flows therethrough. According
to the modified example of the fifth example, the heat exchanging
tube 56 thus structured is bent into U-shape, and arranged in the
vicinity of the evaporating portion 54a of the heat pipe 54.
Therefore, the heat of the liquid phase cooling medium flowing
through the heat exchanging tube 56 is drawn by the cold storage
medium in the tank 42.
[0147] In case of using the ice storage device 41 in the datacenter
whose electrical power consumption is larger than 200 kWh, thereby
requiring larger output of the ice storage device 41, a capacity of
the ice storage device 41 can be increased easily by merely
combining a plurality of the ice storage devices 41 to form a
larger auxiliary cooling system having a required capacity. An
example of combining three ice storage devices 41 in the shield 57
is shown in FIG. 17, and FIG. 18 is a cross sectional view thereof.
Although not especially shown in FIGS. 17 and 18, both of the coil
shaped heat exchanging tube 49 and the U-shaped heat exchanging
tube 56 can be used in this example.
[0148] As shown in FIG. 17, each of the three ice storage device 41
is formed into a cuboid shape, and the plurality of heat pipes 43
are erected in the ice storage device 41. In this example, each of
the ice storage devices 41 is covered with the heat insulating
layer 45 and the waterproof layer 46. The ice storage devices 41
thus unified is enclosed entirely by the soil layer 52. As
described, a thickness of the soil layer 52 is preferably 1 meter,
and the plurality of heat pipes 54 are erected in the soil layer
52. However, in case of combining the plurality of ice storage
devices 41 in this manner, a thickness of a soil layer 52 between
the adjoining ice storage devices 41 can be reduced to be smaller
than 1 meter.
[0149] Thus, the capacity of the ice storage device 41 can be
increased easily by merely combining a plurality of the ice storage
devices 41. Therefore, even in the case where a number of the
computer servers is increased and larger output of the auxiliary
cooling device 41 is required, the larger cold energy can be stored
in the auxiliary cooling device 41 by increasing the number of the
ice storage device 41 without introducing additional air
conditioners and chiller units. In addition, the cold energy of the
frozen soil layer 52 can also be utilized to cool the datacenter 1
by merely arranging the coil shaped heat exchanging tube 49 or the
U-shaped heat exchanging tube 56 in the soil layer 52.
[0150] Next, an assist heat pipe according to the sixth example of
the present invention will be explained with reference to FIG. 19.
In the example shown in FIG. 19, a plurality of server racks 3
housing a plurality of computer servers therein are installed in
the housing of the datacenter 1, and the housing 2 is provided with
an air conditioner 4 for the purpose of cooling the computer
servers by lowering a temperature in the housing 2 raised by the
electronic components of the servers. In addition, in order to
assist the air conditioner 4 by radiating the heat in the housing 2
to the atmosphere, the heat pipe 5 is arranged in the housing 2
above the server rack 3 in the direction of gravitational
force.
[0151] Specifically, as the heat pipes used in the above-explained
examples, the assist heat pipe 5 is also a thermosiphon comprising
an evacuated hollow container, and volatile and condensable working
fluid contained in the container air-tightly. In order to exchange
internal heat and external cold energy efficiently, the container
of the assist heat pipe 5 is also made of material having good heat
conductivity such as copper. In addition, the working fluid of the
assist heat pipe 5 is selected from water, ammonia and
hydrochlorofluorocarbon and so on depending on a condition of
temperature.
[0152] Specifically, according to the example shown in FIG. 19, one
of end portions of the assist heat pipe 5 extending parallel to the
ceiling of the housing 2 above the server rack 3 serves as the
evaporating portion 5a at which the working fluid is heated to be
vaporized by the internal heat of the housing 2. The assist heat
pipe 5 is bent at a substantially right angle while penetrating
through the ceiling to be exposed to the outside of the housing 2.
The other end portion of the assist heat pipe 5 thus exposed to the
outside of the housing 2 to be contacted with the external air
serves as the condensing portion 5b at which the vaporized working
fluid is condensed by radiating the heat thereof to the atmosphere.
In addition, a plurality of fins 6 for radiating and receiving the
heat is arranged on both of the evaporating portion 5a and the
condensing portion 5b. Here, the fins 6 are also formed of heat
conductive material.
[0153] Therefore, in case the internal temperature of the housing 2
is raised by the electronic components to be higher than the
external temperature, or in case the external temperature becomes
lower than the internal temperature of the housing 2, the working
fluid is vaporized in the evaporating portion 5a of the assist heat
pipe 5. The vapor of the working fluid rises toward the condensing
portion 5b where the temperature and the pressure are lower than
those in the evaporating portion 5a, and the internal heat of the
housing 2 thus transported to the condensing portion 5b by the
vaporized working fluid is then radiated to the atmosphere thorough
the fins 6. As a result, the vaporized working fluid is condensed
again in the condensing portion 5b and returned gravitationally to
the evaporating portion 5a. Thus, a thermal diode characteristic of
the assist heat pipe 5 also ensures transport of the heat
unilaterally from evaporating portion 5a toward the condensing
portion 5b thereby radiating the internal heat of the housing 2
unilaterally to the outside of the housing 2. For this reason, the
external heat will not enter into the housing 2 through the assist
heat pipe 5.
[0154] Thus, according to the sixth example, the inner space of the
housing 2 is cooled by transporting the internal heat of the
housing 2 outside of the housing 2 through the assist heat pipe 5
under the condition in which the internal temperature of the
housing 2 is higher than the external temperature. Therefore, a
burden on the air conditioner 4 can be lightened so that an
operating time of the air conditioner 4 can be shortened. As a
result, an electric consumption of the air conditioner 4 is reduced
so that CO.sub.2 emission can be reduced. In addition, since the
external heat will not enter into the housing 2 thorough the assist
heat pipe 5, the internal temperature of the container 2 can be
prevented from being raised by the external heat.
[0155] Although the above exemplary embodiments of the present
invention have been described, it will be understood by those
skilled in the art that the present invention should not be limited
to the described exemplary embodiments, but that various changes
and modifications can be made within the spirit and scope of the
present invention.
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