U.S. patent application number 14/546013 was filed with the patent office on 2015-03-12 for dew condensation detecting device, cooling system and cooling medium flow rate controlling method.
This patent application is currently assigned to FUJITSU LIMITED. The applicant listed for this patent is FUJITSU LIMITED. Invention is credited to Junichi Ogo, Tsuyoshi SO, Norihisa TAKAHASHI, Susumu Takahashi, Yoshinori Uzuka.
Application Number | 20150068702 14/546013 |
Document ID | / |
Family ID | 49757766 |
Filed Date | 2015-03-12 |
United States Patent
Application |
20150068702 |
Kind Code |
A1 |
SO; Tsuyoshi ; et
al. |
March 12, 2015 |
DEW CONDENSATION DETECTING DEVICE, COOLING SYSTEM AND COOLING
MEDIUM FLOW RATE CONTROLLING METHOD
Abstract
A dew condensation detecting device includes a dew condensation
detector and a heat transfer part. The dew condensation detector is
provided to a supply pipe, which supplies a cooling medium from a
cooling medium supply apparatus to a device to be cooled. The dew
condensation detector detects a dew condensation by detecting a
water droplet due to the dew condensation. The heat transfer part
transfers heat from the cooling medium flowing in a return pipe,
which returns the cooling medium from the device to be cooled to
the cooling medium supply apparatus, to the cooling medium flowing
in the supply pipe between the dew condensation detector and the
device to be cooled.
Inventors: |
SO; Tsuyoshi; (Kawasaki,
JP) ; TAKAHASHI; Norihisa; (Kawasaki, JP) ;
Uzuka; Yoshinori; (Kawasaki, JP) ; Ogo; Junichi;
(Kawasaki, JP) ; Takahashi; Susumu; (Yokohama,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJITSU LIMITED |
Kawasaki-shi |
|
JP |
|
|
Assignee: |
FUJITSU LIMITED
Kawasaki-shi
JP
|
Family ID: |
49757766 |
Appl. No.: |
14/546013 |
Filed: |
November 18, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2012/065276 |
Jun 14, 2012 |
|
|
|
14546013 |
|
|
|
|
Current U.S.
Class: |
165/11.1 ;
165/287 |
Current CPC
Class: |
F25D 21/04 20130101;
H05K 7/20736 20130101; G01N 25/66 20130101; H05K 7/20272 20130101;
F25D 21/02 20130101 |
Class at
Publication: |
165/11.1 ;
165/287 |
International
Class: |
F25D 21/02 20060101
F25D021/02; F25D 21/04 20060101 F25D021/04 |
Claims
1. A dew condensation detecting device, comprising: a dew
condensation detector provided to a supply pipe, which supplies a
cooling medium from a cooling medium supply apparatus to a device
to be cooled, the dew condensation detector detecting a dew
condensation by detecting a water droplet due to the dew
condensation; and a heat transfer part that transfers heat from the
cooling medium flowing in a return pipe, which returns the cooling
medium from said device to be cooled to said cooling medium supply
apparatus, to the cooling medium flowing in said supply pipe
between said dew condensation detector and said device to be
cooled.
2. The dew condensation detecting device as claimed in claim 1,
wherein said heat transfer part includes a heat transfer member
that contacts with said supply pipe and said return pipe.
3. The dew condensation detecting device as claimed in claim 2,
wherein said heat transfer member is a metal material that is
joined to said supply pipe and said return pipe.
4. The dew condensation detecting device as claimed in claim 1,
wherein said heat transfer part includes a coupling cover and a
heat transfer material, the coupling cover having a loop form to
surround said supply pipe and said return pipe, the heat transfer
material being filled in a space between said supply pipe and said
return pipe.
5. The dew condensation detecting device as claimed in claim 4,
wherein said heat transfer material includes a thermal sheet or a
thermal compound.
6. The dew condensation detecting device as claimed in claim 1,
wherein said heat transfer part includes a coupling pipe that
supplies a part of the cooling medium flowing in said return pipe
to said supply pipe.
7. The dew condensation detecting device as claimed in claim 6,
wherein one end of said coupling pipe is inserted into said return
pipe and the other end of said coupling pipe is inserted into said
supply pipe, the one end of said coupling pipe being provided with
a flow-in opening through which the cooling medium flows into said
coupling pipe, the other end of said coupling pipe being provided
with a flow-out opening from which the cooling medium flows out of
said coupling pipe.
8. The dew condensation detecting device as claimed in claim 6,
wherein one end of said coupling pipe is inserted into and opens in
said return pipe and the other end of said coupling pipe is
inserted into and opens in said supply pipe, and an inclination
plate is provided to each of said one end and said the other end of
said coupling pipe.
9. The dew condensation detecting device as claimed in claim 1,
further comprising a heating part provided to said supply pipe
between said dew condensation detector and said device to be
cooled.
10. The dew condensation detecting device as claimed in claim 9,
wherein said heating part includes an electric heater.
11. A cooling system, comprising: a device to be cooled that
incorporates an internal part to be cooled by a cooling medium; a
cooling medium supply apparatus that creates the cooling medium
supplied to said device to be cooled; a supply pipe that connects
said device to be cooled to said cooling medium supply apparatus in
order to supply the cooling medium from said cooling medium supply
apparatus to said device to be cooled; a return pipe that connects
said device to be cooled to said cooling medium supply apparatus in
order to return the cooling medium from said device to be cooled to
said cooling medium supply apparatus; a dew condensation detector
provided in a middle of said supply pipe; and a heat transfer part
that transfers heat from the cooling medium flowing in a return
pipe to the cooling medium flowing in said supply pipe between said
dew condensation detector and said device to be cooled.
12. The cooling system as claimed in claim 11, wherein said heat
transfer part includes a heat transfer member that contacts with
said supply pipe and said return pipe.
13. The cooling system as claimed in claim 11, wherein said heat
transfer part includes a coupling pipe that supplies a part of the
cooling medium flowing in said return pipe to said supply pipe.
14. A cooling medium flow rate controlling method for controlling a
flow rate of a cooling medium supplied to a device to be cooled,
the cooling medium flow rate controlling method comprising:
detecting a temperature of the cooling medium discharged from said
device to be cooled; and comparing the detected temperature with a
temperature threshold value and controlling the flow rate of the
cooling medium supplied to said device to be cooled based on a
result of the comparing.
15. The cooling medium flow rate controlling method as claimed in
claim 14, wherein said temperature threshold vale includes an upper
limit threshold value and a lower limit threshold vale, and the
controlling the flow rate includes: increasing the flow rate of the
cooling medium supplied to said device to be cooled when the
detected temperature is higher than the upper limit threshold
value; and decreasing the flow rate of the cooling medium supplied
to said device to be cooled when the detected temperature is lower
than the lower limit threshold value.
16. The cooling medium flow rate controlling method as claimed in
claim 15, wherein the controlling the flow rate includes: comparing
the flow rate of the cooling medium supplied to said device to be
cooled with a flow rate lower limit value when the detected
temperature is lower than the lower limit threshold vale;
decreasing the flow rated of the cooling medium supplied to said
device to be cooled when the flow rate of the cooling medium
supplied to the device to be cooled is higher than or equal to said
flow rate lower limit value; and heating the cooling medium
supplied to said device to be cooled at a position between a dew
condensation detecting position and said device to be cooled when
the flow rate of the cooling medium supplied to the device to be
cooled is lower than said flow rate lower limit value.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application filed
under 35 U.S.C. 111(a) claiming benefit under 35 U.S.C. 120 and
365(c) of PCT International Application No. PCT/JP2012/065276 filed
on Jun. 14, 2012, designating the U.S., the entire contents of the
foregoing application are incorporated herein by reference.
FIELD
[0002] The embodiments discussed herein are directed to a dew
condensation detecting device for detecting water droplets created
by a dew condensation.
BACKGROUND
[0003] If a temperature of a component part of an electronic device
reaches a temperature lower than a dew point of an atmosphere of
the electronic device, a dew condensation occurs on the component
part of the electronic device. Water droplets created by the dew
condensation may cause a corrosion of a metal part of the
electronic device or short-circuiting between electrodes of an
electric circuit provided in the electronic device. Thus, a
malfunction may occur in the electronic device due to the dew
condensation.
[0004] Generally, a temperature and humidity of an environment, in
which a liquid-cooling electronic device is located, and a
temperature of a cooling liquid used in the liquid-cooling
electronic device are controlled and managed in order to prevent an
occurrence of a dew condensation in the liquid-cooling electronic
device. However, if a failure occurs in an air-conditioner or a
temperature abnormality occurs in a cooling-liquid outputting
device, the temperature of the cooling liquid reaching the
electronic device may become lower than the dew point, which
results in the interior of the electronic device being set in a dew
condensed state. Even in such a condition, there may be a case
where a power of the electric device is turned on or the electronic
device is continuously operated. Thus, if an amount of water
droplets due to the dew condensation exceeds a certain amount in
the electronic device, short-circuiting may occur between
electrodes of an electric circuit in the electronic device. The
short-circuiting in the electric circuit may cause a failure in the
electronic device, such as a malfunction of the electric circuit, a
burnout of the electric circuit, etc.
[0005] In order to prevent such a failure due to a dew
condensation, it is suggested to provide a dew condensation sensor
in an electronic device to detect a dew condensation in order to
take measures for preventing a failure due to the dew condensation.
That is, for example, if a dew condensation is detected by the dew
condensation sensor, the electric device is prohibited from being
turned on or the interior of the electronic device is subjected to
a dehydration treatment.
[0006] There are several types of dew condensation sensors. There
if known a dew condensed water detecting sensor that detects a dew
condensation by detecting a water droplet, which is created by a
dew condensation and flows to a detecting part. Such a dew
condensed water detecting sensor generally includes a water droplet
sensor (liquid sensor) and a measuring object formed of a metal on
which a dew condensation tends to occur. The measuring object is
provided to a cold water supply passage between a cold water supply
apparatus and an electronic device so as to be cooled by cold water
supplied from the cold water supply apparatus. Accordingly, if a
temperature of the measuring object becomes lower than a dew point
of the atmosphere, a dew condensation occurs on the measuring
object. That is, the cold water supplied from the cold water supply
apparatus first cools the measuring object of the dew condensed
water detecting sensor, and, thereafter, the cold water is supplied
to the electronic device so as to cool heat-radiating parts in the
electronic device.
[0007] Because the heat capacity of the measuring object of the dew
condensed water sensor is small and the measuring object does not
generate heat, the temperature of the cold water entering the
electronic device after cooling the measuring object is nearly
equal to the temperature of the cold water supplied from the cold
water supply apparatus to the measuring object. Thus, if a dew
condensation occurs on the measuring object, a dew condensation may
simultaneously occur on a cold water passage in the electronic
device.
[0008] It is suggested, in Japanese Laid-Open Patent Application
No. 2006-32515, to prevent a dew condensation in a device by
causing a coolant temperature to rise by reducing an amount of flow
of coolant to be supplied to the device when a dew condensation
sensor provided to an external coolant equipment pipe detects a dew
condensation.
[0009] Additionally, it is suggested, in Japanese Patent No.
3447257, to control a cold water supply apparatus by providing a
dew condensation sensor on an uppermost stream side of a supply
pipe that supplies cold water to a cooler panel.
[0010] Because the dew condensation sensor detects a dew
condensation by detecting a water droplet due to the dew
condensation, it takes a certain time from the time at which a dew
condensation begins until the time at which an amount of a water
droplet due to the dew condensation reaches a measurable amount.
Accordingly, during the period from the time at which the dew
condensation begins in the dew condensation sensor and the
electronic device until the time at which the dew condensation
sensor detects the dew condensation, water droplets may be created
due to the dew condensation even in the electronic device. The
water droplets due to the dew condensation in the electronic device
may cause the above-mentioned failure.
SUMMARY
[0011] There is provided according to an aspect of the embodiments
a dew condensation detecting device, including: a dew condensation
detector provided to a supply pipe, which supplies a cooling medium
from a cooling medium supply apparatus to a device to be cooled,
the dew condensation detector detecting a dew condensation by
detecting a water droplet due to the dew condensation; and a heat
transfer part that transfers heat from the cooling medium flowing
in a return pipe, which returns the cooling medium from the device
to be cooled to the cooling medium supply apparatus, to the cooling
medium flowing in the supply pipe between the dew condensation
detector and the device to be cooled.
[0012] There is provided according to another aspect of the
embodiments a cooling system including: a device to be cooled that
incorporates an internal part to be cooled by a cooling medium; a
cooling medium supply apparatus that creates the cooling medium
supplied to the device to be cooled; a supply pipe that connects
the device to be cooled to the cooling medium supply apparatus in
order to supply the cooling medium from the cooling medium supply
apparatus to the device to be cooled; a return pipe that connects
the device to be cooled to the cooling medium supply apparatus in
order to return the cooling medium from the device to be cooled to
the cooling medium supply apparatus; a dew condensation detector
provided in a middle of the supply pipe; and a heat transfer part
that transfers heat from the cooling medium flowing in a return
pipe to the cooling medium flowing in the supply pipe between the
dew condensation detector and the device to be cooled.
[0013] There is provided according to a further aspect of the
embodiments a cooling medium flow rate controlling method for
controlling a flow rate of a cooling medium supplied to a device to
be cooled, the cooling medium flow rate controlling method
including: detecting a temperature of the cooling medium discharged
from the device to be cooled; and comparing the detected
temperature with a temperature threshold value and controlling the
flow rate of the cooling medium supplied to the device to be cooled
based on a result of the comparison.
[0014] The object and advantages of the embodiments will be
realized and attained by means of the elements and combinations
particularly pointed out in the appended claims.
[0015] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1 is an outline diagram illustrating an entire
structure of an electronic device cooling system provided with a
dew condensation detecting device according to a first
embodiment;
[0017] FIG. 2 is an enlarged cross-sectional view of a heat
transferring part;
[0018] FIG. 3 is an enlarged cross-sectional view of another heat
transferring part;
[0019] FIG. 4 is a flowchart of a dew condensation detecting
process;
[0020] FIG. 5 is an outline diagram illustrating an entire
structure of an electronic device cooling system provided with a
dew condensation detecting device according to a second
embodiment;
[0021] FIG. 6 is an enlarged cross-sectional view of a portion A
encircled by dashed line in FIG. 5;
[0022] FIG. 7 is a perspective view of a connection pipe;
[0023] FIG. 8 is a cross-sectional view of a variation of the
connection pipe;
[0024] FIG. 9 is a flowchart of a cold water flow amount
controlling process;
[0025] FIG. 10 is an outline diagram illustrating an entire
structure of an electronic device cooling system provided with a
dew condensation detecting device according to a third
embodiment;
[0026] FIG. 11 is a flowchart of a cold water flow amount
controlling process performed in the electronic device cooling
system illustrated in FIG. 10; and
[0027] FIGS. 12(a)-(e) are time charts indicating operations and
temperatures in the electronic device cooling system when the cold
water flow amount controlling process illustrated in FIG. 11 is
performed.
DESCRIPTION OF EMBODIMENT(s)
[0028] A description will now be given, with reference to the
drawings, of embodiments.
[0029] FIG. 1 is an outline diagram illustrating an entire
structure of an electronic device cooling system provided with a
dew condensation detection device according to a first
embodiment.
[0030] An electronic device 10 illustrated in FIG. 1 is an example
of a device to be cooled. Specifically, the electronic device 10 is
a liquid cooling type electronic device such as, for example, a
computer, server, etc. A cold cooling water (hereinafter, referred
to as the "cold water") is supplied from a cold water supply
apparatus 12 to the electronic device 10 to cool heat-generating
parts provided in the electronic device 10. The heat-generating
parts include, for example, a semiconductor device, power supply
circuit, etc. The cold water created by the cold water supply
apparatus 12 is supplied to a cooling water passage (not
illustrated in the figure) of the electronic device 10 through a
cold water supply pipe 14. The heat-generating parts are arranged
in the middle of the cooling water passage in the electronic device
10 so that the heat-generating parts are cooled by the cold water,
which absorbs heat from the heat-generating parts, while flowing
through the cooling water passage. The cooling water warmed by
cooling the heat-generating parts (hereinafter, referred to as the
"warm water"), is returned from the cooling water passage of the
electronic device 10 to the cold water supply apparatus 12 through
a warm water return pipe 16.
[0031] In the present embodiment, although the cold water supply
apparatus 12 is a known cooling-water cooling apparatus provided
with a refrigerating machine and a heat exchanger, a cold water
supply apparatus having any structure may be used if it can supply
cold water by cooling the warm water discharged from the electronic
device 10.
[0032] Additionally, although the cooling water is used as a
coolant in the present embodiment, the coolant is not limited to
the cooling water and a coolant such as a cooling liquid may be
used.
[0033] Normally, the cold water supply apparatus 12 creates cold
water of a predetermined temperature by cooling the warm water
flowing out of the warm water return pipe 16, and discharges the
cold water to the cold water supply pipe 14 at a constant flow
rate. Thus, the cold water supply apparatus 12 is provided with
water temperature sensors 12a and 12b to detect the temperature of
the warm water flowing into the cold water supply apparatus 12 from
the warm water return pipe 16 and the temperature of the cold water
supplied from the cold water supply apparatus 12 to the cold water
supply pipe 14, respectively. Further, the cold water supply
apparatus 12 is provided with a flow rate controller 12c to adjust
a flow rate of the cold water supplied to the cold water supply
pipe 14. The flow rate controller 12c may be a flow rate adjust
valve provided to the flow path of the cold water, or may be a
mechanism to adjust a flow rate by adjusting a revolution speed of
a pump for delivering the cold water.
[0034] The cold water supply apparatus 12 is provided with a
control part 12d for controlling the flow rate controller 12c based
on the temperatures detected by the water temperature sensors 12a
and 12b. The control part 12d is configured by a microcomputer
including a CPU, a memory, etc. Generally, a plurality of
electronic devices 10 are provided to one cold water supply
apparatus 12.
[0035] The dew condensation sensor 20, which is an example of a dew
condensation detector, is provided in the middle of the cold water
supply pipe 14 connecting the cold water supply apparatus 12 and
the electronic device 40. If the cold water supply pipe 14 is
relatively short, the dew condensation sensor 20 may be provided at
any position along the cold water supply pipe 14. If the cold water
supply pipe 14 is relatively long, the dew condensation sensor 20
is preferably arranged at a position close to (in the vicinity of)
the electronic device 10. This is because if an environment around
the dew condensation sensor 20 is substantially equal to an
environment inside the electronic device 10 or around the
electronic device 10, the dew condensation detection by the dew
condensation sensor 20 can be regarded as a dew condensation
detection in the electronic device 10.
[0036] The dew condensation sensor 20 detects a water droplet due
to a dew condensation on the measuring object and outputs a dew
condensation detection signal. The dew condensation detection
signal output by the dew condensation sensor 20 is supplied to a
service processor 10b provided in a control part 10a of the
electronic device 10. The service processor 10b is a CPU performing
a control for causing some functions even when the main power
supply of the electric device 10 is shut off and the main function
of the electronic device 10 is inactive. For example, if the dew
condensation detection signal is supplied to the electronic device
10, the service processor 10b can stop the operation of the
electronic device by tuning off the main power of the electronic
device 10.
[0037] A heat transfer part 30, which is an example of a heat
transferring means to transfer heat from the warm water to the cold
water, is provided between the dew condensation sensor 20 and the
electronic device 10. The heat transfer part 30 is provided to
increase the temperature of the cold water entering the electronic
device 10 by supplying heat to the cold water passed through the
dew condensation sensor 20. That is, the heat transfer part 30 is
provided for raising the temperature of the cold water flowing into
the electronic device 10 by a predetermined temperature (for
example, 2.degree. C.) by transferring a part of the heat of the
warm water flowing out of the electronic device 16 to the warm
water return pipe 16.
[0038] In the present embodiment, as illustrated in FIG. 2, a metal
member 40 is used as the heat transfer part 30. The metal member 40
is formed by a metal as a heat transfer material such as, for
example, copper, copper alloy, aluminum, aluminum alloy, etc. The
metal member 40 has a shape, which can fits in a space between the
cold water supply pipe 14 and the warm water return pipe 16.
Portions of the metal member 40 that contact with the cold water
supply pipe 14 and the warm water return pipe 16 are joined to the
cold water supply pipe 14 and the warm water return pipe 16,
respectively, by welding, brazing, soldering, etc., using a
thermally meltable joining material.
[0039] In the part where the metal member 40 is attached, that is,
in the heat transfer part 30, the heat of the warm water is
transferred from the warm water return pipe 16 to the metal member
40 and then transferred to the cold water supply pipe 14 and
further transferred to the cold water flowing in the cold water
pipe supply pipe 14 because the temperature of the warm water
flowing in the warm water return pipe 16 is higher than the
temperature of the cold water flowing in the cold water supply pipe
14. Thus, the cold water flowing in the cold water supply pipe 14
is warmed by the transferred heat, and the cold water flowing into
the electronic device 10 is raised.
[0040] For example, if the temperature of the cold water passing
through the dew condensation sensor 20 is 21.degree. C., a heat is
supplied to the cold water of 21.degree. C. to raise the
temperature of the cold water to 23.degree. C. so that the cold
water of 23.degree. C. is caused to flow into the electronic device
10. The cold water after cooling the electronic parts by flowing
through the electronic device 10, is changed into the warm water
of, for example, 33.degree. C., and is discharged from the
electronic device 10 to the warm water return pipe 16.
[0041] Here, it is assumed that the environment in the server room
in which the electronic device 10 is installed is maintained at a
room temperature of 25.degree. C. and a relative humidity of 50%,
and the temperature of the cold water supplied from the cold water
supply apparatus 12 is 21.degree. C. In such an environment in the
server room, a dew point in the dew condensation sensor 20 and
electronic device 10 acquired from the psychrometric chart is
13.9.degree. C. Accordingly, in such an environment, the
temperature in the dew condensation sensor 20 (21.degree. C. the
same as the cold water) and also the temperature of the cooling
water passage in the electronic device 10 (23.degree. C. the same
as the cold water warmed by the heat transfer part 30 serving as a
heater) are equal to or lower than the dew point (13.9.degree. C.).
Thus, no dew condensation occurs in the dew condensation sensor 20
and the cooling water passage of the electronic device 10.
[0042] Here, it is assumed that the environment in the server room
is changed, for example, due to a failure of an air-conditioner of
the server room, and the temperature and relative humidity in the
server room are raised to 28.degree. C. and 70%. In such a
condition, the dew point in the environment of the server room is
raised to 22.degree. C., which is higher than the temperature
21.degree. C. of the cold water. Accordingly, a dew condensation
occurs in the dew condensation sensor 20 having the same
temperature of 21.degree. C. as the cold water. On the other hand,
a dew condensation does not occur in the electronic device 10
because the cooling water passage in the electronic device 10 is at
23.degree. C., which is the same as the temperature of the cold
water heated by the heat transfer part 30.
[0043] If the environment in the server room continues to change
and the room temperature and relative humidity are continuously
raised, the dew point is further raised from 22.degree. C. Then,
the dew point exceeds the temperature 23.degree. C. of the cold
water, a dew condensation occurs also in the electronic device
10.
[0044] However, a certain period of time is passed from the time at
which the dew point reaches the temperature of 21.degree. C., which
is the temperature of the dew condensation sensor 20, until the
time at which the dew point reaches the temperature of 23.degree.
C., which is the temperature of the cooling water passage in the
electronic device 10. During the period of time, the dew
condensation progresses and water droplets grow, which results in a
sufficient amount of water droplets detectable by the dew
condensation sensor 20. That is, a dew condensation is not
initiated in the electronic device 10 and water droplets are not
created in the electronic device 10 during the period from the time
at which a dew condensation is initiated in the dew condensation
sensor 20 until the time at which the dew condensation sensor 20
outputs the dew condensation detection signal.
[0045] Accordingly, by taking measures such as interrupting a power
supply of the electronic device 10 upon reception of the dew
condensation detection signal from the dew condensation sensor 20,
a failure of the electronic device 10 due to a dew condensation can
be prevented.
[0046] The heat transfer part 30 is not limited to the metal part
40, and the heat transfer part 30 may be formed by a material
having an excellent heat transfer property, such as a ceramic
material, thermo conductive plastic, thermo conductive rubber, etc.
If the thermo conductive plastic is used, a thermo conductive
adhesive may be used as a joining material. If the thermo
conductive rubber is used, it is desirable to apply a thermo
conductive grease or liquid on a connecting part.
[0047] The size and shape of the metal member 40 are determined
according to an amount of heat to be transferred. The amount of
heat to be transferred is, for example, an amount of heat that can
raise the temperature of the cold water from 21.degree. C. to
23.degree. C. or an amount of heat that causes the temperature of
the warm water to drop from 33.degree. C. to 31.degree. C. in the
above description. The amount of heat transferrable by the metal
member 40 is determined by the thermal conductivity of the metal
member 40 and the heat transfer coefficient between the metal
member 40, cold water supply pipe 14 and warm water return pipe
16.
[0048] Additionally, as another embodiment of the heat transfer
part 30, a structure illustrated in FIG. 3 may be used. The heat
transfer part 30 illustrated in FIG. 3 includes a coupling cover 52
wound on the cold water supply pipe 14 and warm water return pip 16
to bundle the cold water supply pipe 14 and warm water return pip
16. The coupling cover 52 is preferably formed by a thermo
conductive material. For example, the coupling cover 52 is formed
by a metal plate such as a copper plate, aluminum plate, etc.
[0049] A filling material 54 (heat transfer material) having a heat
transfer property is filled in a space between the cold water
supply pipe 14 and warm water return pipe 16 that are covered by
the coupling cover 52. The filling material 54 is a material having
an excellent thermal conductivity, such as a thermal sheet, thermal
compound, etc. If a sufficient amount of heat can be transferred by
only the thermal conduction of the filling material 54, the
coupling cover 54 is not necessarily formed by a material having a
heat transfer property, and may be formed by, for example, a
plastic sheet, vinyl sheet, etc.
[0050] Moreover, the heat transfer property of the heat transfer
part 30 may be improved by attaching the metal member 40 as
illustrated in FIG. 2 and further attaching the coupling cover 54
to the circumference of the portion attached with the metal member
40.
[0051] A description is given below, with reference to FIG. 4, of a
dew condensation detecting method in the electronic device cooling
system. FIG. 4 is a flowchart of a dew condensation detecting
process.
[0052] When the dew condensation detecting process is started,
first, the service processor 10b of the control part 10a of the
electronic device 10 acquires a signal from the dew condensation
sensor 20 (step S1) when the electronic device 10 is operated to
cool the heat-generating parts in the electronic device 10.
Subsequently, the service processor 10b of the electronic device 10
determines whether the signal from the dew condensation sensor 20
is a dew condensation detection signal, which indicates that a dew
condensation is detected (step S2). If it is determined in step S2
that the signal from the dew condensation sensor 20 is not the dew
condensation detection signal, the process returns to step S1 to
retrieve the signal from the dew condensation sensor 20.
[0053] On the other hand, if it is determined in step S2 that the
signal from the dew condensation sensor 20 is the dew condensation
detection signal, the process proceeds to step S3. In step S3, the
service processor 10b performs a process for interrupting (turning
off) the power of the electronic device 10. At this time, a
management person may be notified of the dew condensation state by
the display apparatus. The notification may be made by issuing an
alarm. Alternatively, instead of turning off the power of the
electronic device 10, a process for dehydrating inside the
electronic device 10 may be performed.
[0054] While the above-mentioned dew condensation detecting process
is performed, the temperature of the cold water after passing
through the dew point sensor 20 and before entering the electronic
device 10 is raised by the heat transferred by the heat transfer
part 30, and is set to a temperature higher than the temperature of
the cold water in the dew condensation sensor 20. Accordingly,
during a period from an initiation of a dew condensation in the dew
condensation sensor 20 until a detection of the dew condensation by
the dew condensation sensor 20, no dew condensation is initiated in
the electronic device 10. Thus, before a dew condensation is
initiated in the electronic device 10, measures for preventing a
dew condensation such as turning off the power of the electronic
device 10 may be taken to prevent an occurrence of a failure of the
electronic device 10 due to a dew condensation in the electronic
device 10.
[0055] Although the dew condensation sensor 20 and the heat
transfer part 30 are arranged outside and in the vicinity of the
electronic device 10, the dew condensation sensor 20 and the heat
transfer part 30 may be provided in the electronic device 10 if a
sufficient space can be reserved within the electronic device
10.
[0056] A description is given below of a second embodiment. FIG. 5
is an outline diagram illustrating an entire structure of the
electronic device cooling system provided with a dew condensation
detecting device according to the second embodiment. In FIG. 5,
parts that are the same as the parts illustrated n FIG. 1 are given
the same reference numerals, and descriptions thereof will be
omitted.
[0057] In the electronic device cooling system illustrated in FIG.
5, a coupling pipe 60 is used as the heat transfer part 30 for
transferring heat to the cold water. That is, instead of
transferring heat by the metal member 40, a part of the warm water
flowing in the warm water return pipe 16 is returned to the cold
water supply pipe 14 through the coupling pipe 60 to mix the part
of the warm water into the cold water to raise the temperature of
the cold water. The coupling pipe 60 serves as the heat transfer
part 30 because the coupling pipe 60 transfers the heat of the warm
water flowing in the warm water return pipe 16 to the cold water
flowing in the cold water supply pipe 14.
[0058] FIG. 6 is an enlarged cross-sectional view of the part
encircled by a dashed line A in FIG. 5. The coupling pipe 60 is
provided between the cold water supply pipe 14 and the warm water
return pipe 16 in a state where an end 60a of the coupling pipe 60
is inserted into the interior of the warm water return pipe 16 in
the vicinity of the electronic device 10 and the other end 60b of
the coupling pipe 60 is inserted into the interior of the cold
water supply pipe 14 between the dew condensation sensor and the
electronic device 10. A flow-in opening 62 is provided in the end
60a of the coupling pipe 60a and a flow-out opening 64 is formed on
the outer end 60b of the coupling pipe 60.
[0059] The flow-in opening 62 is open toward an upstream of the
flow of the warm water in the warm water return pipe 16. The
flow-out opening 64 is open toward a downstream of the flow of the
cold water in the cold water supply pip 14. Accordingly, when the
warm water discharged from the electronic device 10 flows in the
warm water return pipe 16, a part of the warm water flowing in the
warm water return pipe 16 flows into the flow-in opening 62 of the
coupling pipe 60. Then, the warm water flows through the coupling
pipe 60 and flows into the cold water supply pipe 14 through the
flow-out opening 64. That is, a part of the warm water discharged
from the electronic device 10 flows though the coupling pipe 60 and
is mixed with the cold water immediately before the electronic
device 10. Thereby, the temperature of the cold water supplied to
the electronic device 10 can be raised by the heat of the warm
water mixed to the cold water.
[0060] For example, if the temperature of the cold water passing
though the dew condensation sensor 20 is 21.degree. C., the
temperature of the cold water is raised to, for example, 23.degree.
C. by mixing the warm water so that the cold water of 23.degree. C.
enters the electronic device 10. It is assumed that the cold water
which has cooled the electronic parts by passing through the
electronic device 10 is turned into the warm water of, for example,
33.degree. C., and then discharged from the electronic device 10 to
the warm water return pipe 16.
[0061] For example, it is assumed that the environment in the serve
room in which the electronic device 10 is installed is maintained
at a room temperature of 25.degree. C. and a relative humidity of
less than or equal to 50%, and the temperature of the cold water
supplied from the cold water supply apparatus 12 is 21.degree. C.
Moreover, it is assumed that a flow rate of the warm water
(33.degree. C.) flowing through the coupling pipe 60 is 450 ml/min.
The warm water is supplied to the cold water after being passed
though the dew condensation sensor 20 through the coupling pipe 60.
If the flow rate of the warm water (33.degree. C.) flowing through
the coupling pipe 60 is 150 ml/min, the cold water of 450 ml/min
mixed with the warm water (33.degree. C.) of 150 ml/min is supplied
to the electronic device 10. The temperature of the cold water
supplied to the electronic device 10 is raised due to the joining
of the warm water and turned to 23.degree. C. Thus, the cold water
(23.degree. C.) of 600 ml/min is supplied to the electronic device
10.
[0062] If an amount of heat generated by the electronic parts
provided in the electronic device 10 is 420 W, the cold water of
the temperature of 23.degree. C. and the flow rate of 600 ml/min
turns into the warm water of the temperature of 33.degree. C. by
absorbing the amount of heat of 420 W, and is discharged into the
warm water return pipe 16. A part of the warm water of 33.degree.
C. (150 ml/min as mentioned above) flows into the coupling pipe 60
immediately after being discharged from the electronic device 10,
and the rest of the warm water (33.degree. C.) of 450 ml/min
returns to the cold water supply device 12. The cold water supply
apparatus 12 cools the warm water (33.degree. C.) of 450 ml/min to
create the cold water (21.degree. C.) of 450 ml/min, and supplies
the created cold water to the cold water supply pipe 14.
[0063] It is appreciated that if the above-mentioned environment is
established in the server room, the dew point in the dew
condensation sensor 20 and the electronic device is acquired as
13.9.degree. C. from the psychrometric chart. Accordingly, in this
environment, there is no dew condensation occurs in the dew
condensation sensor 20 and also in the cooling water passage in the
electronic device 10 because both the temperature in the dew
condensation sensor 20 (21.degree. C. which is the same as the cold
water) and the temperature in the cooling water passage in the
electronic device 10 (23.degree. C. which is the same as the cold
water heated by the heat transfer part 30 serving as a heater) are
lower than the dew point (13.9.degree. C.).
[0064] Here, it is assumed that the environment in the serve room
is changed due to, for example, a failure in the air-conditioner of
the server room and the room temperature is raised to 28.degree. C.
and the relative humidity is raised to 70%. In this condition, the
dew point in the environment in the server room is raised to
22.degree. C., which is higher than the temperature 21.degree. C.
of the cold water. Accordingly, a dew condensation occurs in the
dew condensation sensor 20 having the temperature of 21.degree. C.,
which is the same as the cold water. On the other hand, the cooling
water passage in the electronic device 10 is at 23.degree. C.,
which is the same as the temperature of the cold water, which is
raised by the heat transfer part 30. In this case, a dew
condensation does not occur in the electronic device 10 because the
temperature of the cooling water passage in the electronic device
10 (23.degree. C.) is higher than the dew point 22.degree. C.
[0065] If the environment in the server room is continuously
changed and the room temperature and the relative humidity are
continuously raised, the dew point is raised further from
22.degree. C. Then, if the dew point exceeds the temperature
23.degree. C. of the cold water, a dew condensation occurs also in
the electronic device 10.
[0066] However, it takes a certain period of time from the time at
which the dew point reaches the temperature 21.degree. C. of the
dew condensation sensor 20 until the time at which the dew point
reaches the temperature 23.degree. C. of the cooling water passage
in the electronic device 10. During this period of time, the dew
condensation progresses in the dew condensation sensor 20, which
results in a growth of the water droplets and finally an amount of
water droplets detectable by the dew condensation sensor 20 is
created. That is, no dew condensation is initiated and no water
droplet is created in the electronic device 10 during the period of
time from the time at which a dew condensation is initiated in the
dew condensation sensor 20 until the time at which the dew
condensation sensor 20 output the dew condensation detection
signal.
[0067] As mentioned above, similar to the first embodiment, the
temperature of the cold water after passing through the dew
condensation sensor 20 can be raised in the present embodiment,
thereby providing the same effect as the first embodiment.
Accordingly, a failure of the electronic device 10 due to a dew
condensation can be prevented by taking measures such as
interrupting the power of the electronic device 10 upon receipt of
the dew condensation detection signal from the dew condensation
sensor 20.
[0068] Although the coupling pipe 60 having the shape illustrated
in FIG. 7 is used as the heat transfer part 30, the shape of the
coupling pipe 60 is not limited to that illustrated in FIG. 7.
There are many other shapes and configurations, which can take a
part of the warm water flowing in the warm water return pipe 16 and
supplies the warm water to the cold water supply pipe 14 other than
the shape and configuration illustrated in FIG. 7. As an example,
inclination plates 72 and 74 may be provided to both ends 70a and
70b of a cylindrical pipe 70 having open ends, respectively, as
illustrated in FIG. 8 so as to control a flow of the warm water.
Alternatively, although not illustrated in the figures, both ends
of the cylindrical pipe 70 may be cut obliquely and the cylindrical
pipe 70 may be attached to the warm water return pipe 16 and cold
water supply pipe 14 so that the obliquely cut surface is directed
toward the upstream side of the flow of the warm water on the side
of the warm water return pipe 16 and the obliquely cut surface is
directed toward the downstream side of the flow of the cold water
on the side of the cold water supply pipe 14.
[0069] Here, in the above-mentioned first and second embodiments,
if the amount of heat generated by the electronic parts, which are
heat-generating parts, in the electronic device 10 is fixed, a
difference in the temperature between the dew condensation sensor
20 and the electronic parts in the electronic device 10 is fixed.
Accordingly, a period of time from the time at which a dew
condensation is detected by the dew condensation sensor 20 until
the time when a dew condensation occurs in the electronic device 10
is fixed. The electronic device 10 such as a server or the like may
generate a different amount of heat depending on the type of the
electronic device 10. Moreover, the amount of heat generated by the
same electronic device 10 may vary due to a fluctuation in a load
applied to the electronic parts.
[0070] Thus, an appropriate temperature difference may be set by
adjusting an amount of heat transferred by the heat transfer part
30 so that an operation of the electronic device 10 is stopped
safely by interrupting a system power supply after the dew
condensation sensor 20 detects a dew condensation and before a dew
condensation occurs in the electronic device 10. If an appropriate
design is performed beforehand with respect to an electronic device
having a small load fluctuation, measures for a dew condensation
can be taken by merely providing the heat transfer part 30 as is in
the first and second embodiments.
[0071] On the other hand, in an electronic device having a large
load fluctuation such as, for example, a server or the like, if an
amount of heat transferred by the heat transfer part 30 is set in
accordance with a state where a load to electronic parts is
smallest (a state where an amount of heat generation is small),
cooling for the electronic parts is insufficient when the load is
increased. Thus, an operating temperature of the electronic parts
is raised, which may cause a reduction in the service life and an
increase in the failure rate of the electronic parts. On the
contrary, if the amount of heat transferred by the heat transfer
part 30 is set in accordance with a state where the load to the
electronic parts is largest, a temperature difference between the
temperature of the dew condensation sensor 20 and the temperature
inside the electronic device 10 is decreased. In such a condition,
a period of time from the time at which the dew condensation sensor
20 detects a dew formation until the time at which a dew
condensation occurs in the electronic device 10 is short, and there
may be a case where the electronic device 10 cannot be stopped by
reliably interrupting the system power supply.
[0072] In order to solve such a problem, a flow rate of the cold
water supplied from the cold water supply apparatus 12 is
controlled and adjusted based on the temperature of the warm water
returning to the cold water supply apparatus 12 by flowing through
the warm water return pipe 16. That is, a measurement is taken for
the temperature of the warm water returned to the cold water supply
apparatus 12 to control a flow rate of the cold water created by
the cold water supply apparatus 12 base on the measured
temperature. In this case, an amount of supply of the cold water is
set to a flow rate corresponding to a state where the load is
smallest in the initial setting. If the temperature of the warm
water exceeds a certain threshold value, the cooling capacity of
the cold water with respect to electronic parts is increased based
on an increase in the flow rate of the cold water supplied to the
electronic device 10, thereby suppressing the operating temperature
of the electronic parts. Thereby, also the temperature difference
between the temperature of the dew condensation sensor 20 and the
temperature of the electronic parts can be maintained to fall
within a fixed range.
[0073] FIG. 9 is a flowchart of a cold water flow rate controlling
process for adjusting an amount of supply of the cold water. The
cold water flow rate controlling process is performed repeatedly at
each time interval.
[0074] When the cold water flow rate controlling process is
started, first, the control part 12d of the cold water supply
apparatus 12 acquires a temperature Tw of the warm water returned
to the cold water supply apparatus 12 by flowing through the warm
water return pipe 16 (step S11). The temperature Tw of the warm
water can be detected by a water temperature sensor 12a.
[0075] Then, the control part 12d of the cold water supply
apparatus 12 compares the acquired temperature Tw with a
temperature threshold vale (step S12). The temperature threshold
includes an upper limit threshold value UTH and a lower limit
threshold value LTH. If the temperature Tw of the warm water is
lower than or equal to the upper limit threshold value UTH and
higher than or equal to the lower limit threshold vale LTH, it is
determined that the temperature of the warm water returned is an
appropriate temperature and cooling for the electronic parts in the
electronic device 10 is performed appropriately, and the process is
ended. Although the cold water flow rate controlling process is
repeatedly performed at a fixed time interval, the process may
return to step S11 so that a subsequent process is initiated
immediately after the process is ended.
[0076] If the temperature Tw of the warm water is higher than the
upper limit threshold temperature UTH, it is determined that the
cooling of the electronic parts in the electronic device 10 is not
sufficient, and the process proceeds to step S13. In step S13, the
flow rate of the cold water (21.degree. C.) supplied to the cold
water supply pipe 14 (that is, the electronic device 10) from the
cold water supply apparatus 12) is increased by a predetermined
amount, and, thereafter, the process is ended. Although the cold
water flow rate controlling process is repeatedly performed at a
fixed time interval, the process may return to step S11 after
completing the process of step S13 so that a subsequent process is
initiated immediately after the process is ended.
[0077] If the temperature Tw of the warm water is lower than the
lower limit threshold temperature LTH, it is determined that the
cooling for the electronic parts in the electronic device 10 is too
much, and the process proceeds to step S14. In step S14, the flow
rate of the cold water (21.degree. C.) supplied to the cold water
supply pipe 14 (that is, the electronic device 10) from the cold
water supply apparatus 12 is decreased by a predetermined amount,
and, thereafter, the process is ended. Although the cold water flow
rate controlling process is repeatedly performed at a fixed time
interval, the process may return to step S11 after completing the
process of step S14 so that a subsequent process is initiated
immediately after the process is ended.
[0078] A description is given below of a third embodiment. FIG. 10
is an outline diagram illustrating an entire structure of an
electronic device cooling system provided with a dew condensation
detecting device according to the third embodiment. In FIG. 10,
parts that are the same as the parts illustrated in FIG. 5 are
given the same reference numerals, and descriptions thereof will be
omitted.
[0079] In the electronic device cooling system illustrated in FIG.
10, similar to the second embodiment, the coupling pipe 60 is used
as the heat transfer part 30 for transferring heat to the cold
water. The metal member 40 may be used as the heat transfer part 30
as is in the first embodiment.
[0080] In the present embodiment, a heater 80 as an example of a
heating part is provided between the dew condensation sensor 20 and
the electronic device 10. The heater 80 is provided for raising the
temperature of the cold water entering the electronic device 10 by
heating the cold water passed though the dew condensation sensor
20. In the above-mentioned first and second embodiments, the
temperature of the cold water passed through the dew condensation
sensor 20 is raised by the heat transferred through the heat
transfer part 30 so that the cold water becomes the cold water
having a higher temperature by a predetermined temperature, and is
supplied to the electronic device 10.
[0081] However, if, for example, the electronic device 10 is set in
a standby state and a load to the electronic parts becomes
extremely small, there may be a case where the temperature of the
warm water discharged from the electronic device 10 becomes
extremely low. In such a case, the temperature difference between
the temperature of the dew condensation sensor 20 and the
temperature inside the electronic device 10 cannot be sufficient
large. Thus, a period of time from the time at which a dew
condensation is detected by the dew condensation sensor 20 until
the time at which a dew condensation occurs in the electronic
device 10 cannot be sufficiently large.
[0082] Accordingly, in the present embodiment, if the temperature
of the warm water becomes extremely low, a dew condensation in the
electronic device 10 is suppressed by raising the temperature of
the cold water supplied to the electronic device 10 by driving the
heater 80 to heat the cold water by the heat generated by the
heater 80.
[0083] Although the dew condensation sensor 20, heat transfer part
30 (coupling pipe 60) and heater 80 are arranged outside the
electronic device 10 but in the vicinity of the electronic device
10 in FIG. 10, the dew condensation sensor 20, heat transfer part
30 (coupling pipe 60) and heater 80 may be arranged in the
electronic device 10 if a sufficient space can be reserved in the
electronic device 10.
[0084] Moreover, although the heater 80 is provided between the
coupling pipe 60 and the electronic device 10 in FIG. 10, the
heater may be provided between the dew condensation sensor 20 and
the coupling pipe 60, or the heater 80 may be attached to the dew
condensation sensor 20. In this case, an insulating material is
preferably provided between the heater and the dew condensation
sensor 20 so that the heat of the heater 80 is not transferred to
the dew condensation sensor 20. As mentioned above, the heater 80
may be arranged at any position if it can raise the temperature of
the cold water after exiting the dew condensation sensor 20 and
before entering the electronic device 10. The dew condensation
sensor 20, heat transfer part 30 (coupling pipe) and heater 80
together constitute a dew condensation detecting device.
[0085] Moreover, a heater that performs heating using an electric
energy such as an electric heater (resistance heating heater) or
conductive heater may be used as the heater 80. Alternatively,
instead of the heater 80, heating may be performed using heat from
a heating-radiating member of a peripheral device of the electric
device 10.
[0086] FIG. 11 is a flowchart of a cold water flow rate controlling
process performed in the electronic device cooling system
illustrated in FIG. 10. The cold water flow rate controlling
process is performed repeatedly at a fixed time interval. In FIG.
11, steps that are the same as the steps illustrated in FIG. 9 are
given the same step numbers, and descriptions thereof will be
omitted.
[0087] In the cold water flow rate controlling process illustrated
in FIG. 11, if it is determined in step S12 that the temperature Tw
of the warm water is lower than the lower limit threshold value
LTH, it is determined that the cooling for the electronic parts in
the electronic device 10 is too much, and the process proceeds to
step S21. In step S21, the control part 12d of the cold water
supply apparatus 12 determines whether a flow rate of the cold
water (21.degree. C.) supplied from the cold water supply apparatus
12 to the cold water supply pipe 14 (that is, the electronic device
10) is higher than or equal to a flow rate lower limit value.
[0088] If the flow rate of the cold water supplied to the
electronic device 10 is higher than or equal to the flow rate lower
limit value (YES in step S21), the process proceeds to step S22. In
step S22, the flow rate of the cold water (21.degree. C.) supplied
from the cold water supply apparatus 12 to the cold water supply
pipe 14 (that is, the electronic device 10) is reduced by a
predetermined amount, and, thereafter, the process is ended.
Although the cold water flow rate controlling process is repeatedly
performed at a fixed time interval, the process may return to step
S11 after completing the process of step S22 so that a subsequent
process is initiated immediately after the process is ended.
[0089] On the other hand, if the flow rate of the cold water
supplied to the electronic device 10 is less than the flow rate
lower limit value (NO in step S21), the process proceeds to step
S23. In step S23, the flow rate of the cold water (21.degree. C.)
supplied from the cold water supply apparatus 12 to the cold water
supply pipe 14 (that is, the electronic device 10) is maintained
unchanged, and the heater 80 is activated. Thereby, the temperature
of the cold water supplied to the electronic device 10 is raised by
the heating by the heater 80, which results in a sufficient
temperature difference between the temperature of the dew
condensation sensor 20 and the temperature inside the electronic
device 10. After the heater 80 is activated in step S23, the
process is ended. Although the cold water flow rate controlling
process is repeatedly performed at a fixed time interval, the
process may return to step S11 after completing the process of step
S23 so that a subsequent process is initiated immediately after the
process is ended.
[0090] FIGS. 12(a)-(e) are time charts indicating changes in
operations and temperatures of various parts when the cold water
flow rate controlling process illustrated in FIG. 11 is
performed.
[0091] The electronic parts in the electronic device 10 are
operated and a certain amount of heat is generated by the
electronic parts, and the electronic parts are sufficiently cooled
by a certain amount of the cold water supplied from the cold water
supply apparatus 12 until time A. Accordingly, the temperature of
the warm water discharged from the electronic device 10 (that is,
the temperature of the warm water returning to the cold water
supply apparatus 12) is maintained at a fixed temperature. Thus, a
temperature difference between the temperature of the dew
condensation sensor 20 and the temperature inside the electronic
device 10 is maintained constant at a sufficient temperature
difference.
[0092] The operating state of the electronic device 10 begins to
change and the load to the electronic parts begins to decrease at
time A, and, thereby, the amount of heat generated by the
electronic parts decreases as illustrated in FIG. 12(a). In this
condition, as illustrated in FIG. 12(d), the temperature of the
warm water discharged from the electronic device 10 begins to fall
with a slight time difference (slight time delay). Upon detection
of the temperature fall of the warm water from the detection value
of the water temperature sensor 12a, the control part 12d of the
cold water supply apparatus 12 causes, as illustrated in FIG.
12(b), the amount of supply of the cold water (flow rate of the
cold water) to decrease by a predetermined flow rate. As a result,
as illustrated in FIG. 12(d), the temperature of the warm water
slightly falls and, then, rises and returns to the original fixed
temperature. At this time, as illustrated in FIG. 12(e) the
temperature difference between the dew condensation sensor 20 and
the temperature inside the electronic device 10 slightly decreases
and then returns to the original temperature difference. The
above-mentioned state changes are caused by the process of steps
S11, S12, S21 and S22 in the flowchart of FIG. 11.
[0093] Subsequently, the operating state of the electronic device
10 begins to change and the load to the electronic parts begins to
increase, and, thereby, as illustrated in FIG. 12(a), the amount of
heat generated by the electronic parts begins to increase at time
B. In this condition, as illustrated in FIG. 12(d), the temperature
of the warm water discharged from the electronic device 10 begins
to rise with a slight time difference (slight time delay). Upon
detection of the temperature rise of the warm water from the
detection value of the water temperature sensor 12a, the control
part 12d of the cold water supply apparatus 12 causes, as
illustrated in FIG. 12(b), the amount of supply of the cold water
(the flow rate of the cold water) to increase by a predetermined
flow rate. As a result, as illustrated in FIG. 12(d), the
temperature of the warm water slightly rises and, then, falls and
returns to the original fixed temperature. At this time, as
illustrated in FIG. 12(e), the temperature difference between the
dew condensation sensor 20 and the temperature inside the
electronic device 10 slightly increases and then returns to the
original temperature difference. The above-mentioned state changes
are caused by the process of steps S11, S12 and S13 in the
flowchart of FIG. 11.
[0094] Subsequently, the operating state of the electronic device
10 begins to change and the load to the electronic parts begins to
greatly decrease, and, thereby, as illustrated in FIG. 12(a), the
amount of heat generated by the electronic parts begins to greatly
decease at time C. In this condition, as illustrated in FIG. 12(d),
the temperature of the warm water discharged from the electronic
device 10 begins to fall with a slight time difference (slight time
delay). Upon detection of the temperature fall of the warm water
from the detection value of the water temperature sensor 12a, the
control part 12d of the cold water supply apparatus 12 causes the
amount of supply of the cold water (flow rate of the cold water) to
decrease by a predetermined flow rate.
[0095] However, because the decrease in the amount of heat
generated by the electronic parts is large, the temperature of the
warm water continues to rise even after the amount of supply of the
cold water is decreased, and, thereby, the amount of supply of the
cold water is further decreased. Thus, the amount of supply of the
cold water (the flow rate of the cold water) greatly decreases, and
becomes smaller than the flow rate lower limit value as illustrated
in FIG. 12(b). Then, the heater 80 is turned on so that a voltage
is applied to the heater 80, as illustrated in FIG. 12(c), in order
to maintain the temperature difference by raising the temperature
of the cold water. Thus, the heater 80 generates heat and the cold
water supplied to the electronic device 10 is heated.
[0096] When the cold water to be supplied to the electronic device
10 is heated, the temperature of the warm water discharged from the
electronic device 10 is raised again and returns to the original
temperature difference as illustrated in FIG. 12(d). Thereby, the
temperature difference also increases and returns to the original
temperature difference. Thus, a sufficient period of time from the
time at which the condensation sensor 20 detects a dew condensation
until the time at which a dew condensation occurs in the electronic
device 10 can be reserved, which allows taking measures for
preventing a dew condensation in the electronic device 10, such as
turning off the system power supply.
[0097] The state changes after time C correspond to the state
changes due to the process of steps S11, S12, S21, S22, S112, S12,
S21 and S23 in the flowchart illustrated in FIG. 11.
[0098] All examples and conditional language recited herein are
intended for pedagogical purposes to aid the reader in
understanding the principles of the invention and the concepts
contributed by the inventor to furthering the art, and are to be
construed a being without limitation to such specifically recited
examples and conditions, nor does the organization of such examples
in the specification relates to a showing of the superiority and
inferiority of the invention. Although the embodiment(s) of the
present invention (s) has(have) been described in detail, it should
be understood that the various changes, substitutions, and
alterations could be made hereto without departing from the spirit
and scope of the invention.
* * * * *