U.S. patent application number 13/182714 was filed with the patent office on 2012-10-04 for water-cooled electrical apparatus.
This patent application is currently assigned to Mitsubishi Electric Corporation. Invention is credited to Masahisa Asaoka, Kazuyuki Muto, Shinichi Ogusa, Nobuki SHIMOKAJI, Michihiro Tadokoro, Hitoshi Teramoto.
Application Number | 20120247749 13/182714 |
Document ID | / |
Family ID | 46925717 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120247749 |
Kind Code |
A1 |
SHIMOKAJI; Nobuki ; et
al. |
October 4, 2012 |
WATER-COOLED ELECTRICAL APPARATUS
Abstract
An objective is to prevent excessive temperature decrease of
cooling water and to reduce energy loss by a heater. A water-cooled
electrical apparatus includes an electrical device 2 placed
indoors, a pump 3 for circulating cooling water for cooling the
electrical device, a cooler 5, placed outdoors, for cooling the
cooling water, a heater 6 for heating the cooling water, and a main
pipe 4 forming a closed loop so that the cooling water circulates
through the electrical device, the pump, the cooler, and the
heater. The water-cooled electrical apparatus further includes a
bypass pipe 11 bypassing between bifurcations 9 and 10, provided at
inlet and outlet sides of the cooler, for flow-dividing the cooling
water, and at least one of a first flow amount control valve 7
provided along the main pipe between the bifurcations, and a second
flow amount control valve 12 provided along the bypass pipe.
Inventors: |
SHIMOKAJI; Nobuki; (Tokyo,
JP) ; Asaoka; Masahisa; (Tokyo, JP) ;
Teramoto; Hitoshi; (Tokyo, JP) ; Ogusa; Shinichi;
(Tokyo, JP) ; Muto; Kazuyuki; (Tokyo, JP) ;
Tadokoro; Michihiro; (Tokyo, JP) |
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
46925717 |
Appl. No.: |
13/182714 |
Filed: |
July 14, 2011 |
Current U.S.
Class: |
165/253 ;
165/64 |
Current CPC
Class: |
F25D 17/02 20130101;
F25D 21/04 20130101; F25D 2400/02 20130101 |
Class at
Publication: |
165/253 ;
165/64 |
International
Class: |
F25B 29/00 20060101
F25B029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2011 |
JP |
2011-079311 |
Claims
1. A water-cooled electrical apparatus comprising: an electrical
device placed indoors; a pump for circulating cooling water for
cooling the electrical device; a cooler, placed outdoors, for
cooling the cooling water; a heater for heating the cooling water;
a main pipe forming a closed loop so that the cooling water
circulates through the electrical device, the pump, the cooler, and
the heater; a bypass pipe bypassing between bifurcations, provided
at inlet and outlet sides of the cooler, for flow-dividing the
cooling water; and at least one of a first flow amount control
valve provided along the main pipe between the bifurcations, and a
second flow amount control valve provided along the bypass
pipe.
2. A water-cooled electrical apparatus as recited in claim 1,
further comprising: a water temperature meter for measuring water
temperature of the cooling water flowing out from the cooler; and a
controller that receives a signal related to the water temperature
from the water temperature meter, and controls, based on the
signal, an opening degree of the first flow amount control valve or
the second flow amount control valve.
3. A water-cooled electrical apparatus as recited in claim 2,
wherein the controller controls in such a way that the higher the
water temperature is, the larger the opening degree of the first
flow amount control valve is set, or the smaller the opening degree
of the second flow amount control valve is set.
4. A water-cooled electrical apparatus as recited in claim 1,
wherein both the first flow amount control valve and the second
flow amount control valve are provided.
Description
TECHNICAL FIELD
[0001] The present invention relates to a water-cooled electrical
apparatus cooled by cooling water.
BACKGROUND ART
[0002] A conventional water-cooled electrical apparatus has been
configured in such a way that an electrical device (such as an
inverter) to be cooled, a pump for circulating cooling water
cooling the electrical device, and a cooling device for cooling the
cooling water heated by heat generated from the electrical device
are connected through a pipe to form a closed loop (for example,
Patent Document 1).
PRIOR ART DOCUMENT
Patent Document
[0003] [Patent Document 1] Japanese Laid-Open Patent Publication
H09-199648 (pages 2-3, FIGS. 1-2)
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0004] In the above described conventional water-cooled electrical
apparatus, because, in many cases, the cooling device is placed
outdoors, and the apparatus is configured in such a way that the
entire amount of the cooling water circulates through this cooling
device, when the outdoor temperature decreases, excessive
temperature decrease of the cooling water has occasionally
occurred. In this case, the difference between the water
temperature of the circulating cooling water and the indoor room
temperature increases, and due to the temperature of indoor air
being decreased to that of the cooling water, the water vapor is
saturated to cause dew condensation on the surface of the
electrical device whereby a problem for securing insulating ability
has occasionally occurred. In order to prevent such dew
condensation, the cooling water can be heated by providing a heater
at a portion of the closed loop of the cooling water circuit;
however, when the cooling water is heated to a level where the dew
condensation does not occur, because the temperature decrease of
the cooling water is large, a problem has occurred that large
energy loss occurs in the heater.
[0005] An objective of the present invention, which is made to
solve the above described problem, is to prevent the excessive
temperature decrease of the cooling water and to reduce the energy
loss in the heater.
Means for Solving the Problem
[0006] A water-cooled electrical apparatus according to the present
invention includes an electrical device placed indoors, a pump for
circulating cooling water for cooling the electrical device, a
cooler, placed outdoors, for cooling the cooling water, a heater
for heating the cooling water, and a main pipe forming a closed
loop so that the cooling water circulates through the electrical
device, the pump, the cooler, and the heater.
[0007] The water-cooled electrical apparatus further includes a
bypass pipe bypassing between bifurcations, provided at inlet and
outlet sides of the cooler, for flow-dividing the cooling water,
and at least one of a first flow amount control valve provided
along the main pipe between the bifurcations, and a second flow
amount control valve provided along the bypass pipe.
Advantageous Effect of the Invention
[0008] According to the water-cooled electrical apparatus of the
present invention, the bypass pipe, and at least one of the first
flow amount control valve provided along the main pipe between the
bifurcations and the second flow amount control valve provided
along the bypass pipe are included; thereby, the water temperature
can be controlled by varying a mixing ratio between relatively cool
cooling water circulating from the main pipe to the electrical
device through the cooler and relatively warm cooling water
circulating through the bypass pipe to the electrical device.
Therefore, because the cooling water can be controlled at higher
temperature comparing to the conventional one in which the entire
amount of the cooling water circulates through the cooling device,
excessive temperature decrease of the cooling water can be
prevented and the energy loss by the heater can be reduced.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a view illustrating a configuration of a
water-cooled electrical apparatus according to Embodiment 1 of the
present invention;
[0010] FIG. 2 is a graph representing a relationship between
opening degrees of the first flow amount control valve and the
second flow amount control valve in the water-cooled electrical
apparatus according to Embodiment 1 of the present invention;
[0011] FIG. 3 is a graph representing a relationship between the
opening degrees of the flow amount control valves and flow amounts
of the cooling water in the water-cooled electrical apparatus
according to Embodiment 1 of the present invention;
[0012] FIG. 4 is a graph representing a relationship between the
opening degree of the flow amount control valve and flow amounts of
the cooling water in the water-cooled electrical apparatus
according to Embodiment 1 of the present invention;
[0013] FIG. 5 is a graph representing a relationship between the
opening degree of the flow amount control valve and flow amounts of
the cooling water in the water-cooled electrical apparatus
according to Embodiment 1 of the present invention;
[0014] FIG. 6 is a graph representing an operation mode of the
water-cooled electrical apparatus according to Embodiment 1 of the
present invention; and
[0015] FIG. 7 is a graph representing an operation mode of a
water-cooled electrical apparatus according to Embodiment 2 of the
present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1
[0016] FIG. 1 is a view representing a configuration of a
water-cooled electrical apparatus according to Embodiment 1 of the
present invention. In this figure, cooling water ejected from an
electrical device 2 circulates through a main pipe 4 by a pump 3.
In addition to the above, a cooler 5, a heater 6, a first flow
amount control valve 7, and a water temperature meter 8 are
connected to the main pipe 4, where the main pipe 4 forms a closed
circuit in which the cooling water circulates through these units.
Bifurcations 9 and 10 for flow-dividing the cooling water are
provided at inlet and outlet sides of the cooler 5. A path between
both the bifurcations 9 and 10 is bypassed by a bypass pipe 11,
where a second flow amount control valve 12 is provided along the
bypass pipe 11. Here, numeral 13 schematically represents a
boundary between an indoor region in which the electrical device 2
is placed and an outdoor region. In this embodiment, only the
cooler 5 and the water temperature meter 8 are placed outdoors,
while the other units are placed indoors.
[0017] The cooling water heated by the electrical device 2 is
pressurized by the pump 3, flows into the cooler 5 through the main
pipe 4 in the arrow direction in the figure, and then cooled by the
cooler 5 placed outdoors. The cooled cooling water returns to the
indoor region again, and then repeats circulation through the main
pipe 4. The heater 6 for heating to increase the temperature of the
cooling water is provided therein in addition to the electrical
device 2, and the water temperature of the cooling water flowing
out from the cooler 5 is measured by the water temperature meter 8
provided at an outlet of the cooler 5. Moreover, in the
water-cooled electrical apparatus according to this embodiment, a
controller 14 is provided to receive a signal relating to the water
temperature from the water temperature meter 8 and control the
opening degree of the first flow amount control valve 7 or the
second flow amount control valve 12 based on the signal.
[0018] The cooling-water bypass circuit 11 is provided in this
embodiment; accordingly, by controlling the opening degree of the
first flow amount control valve 7 provided along the main pipe 4
between both the bifurcations 9 and 10 and the opening degree of
the second flow amount control valve 12 provided along the bypass
pipe 11, the amounts of the cooling water flowing through the main
pipe 4 and the bypass pipe 11 can be controlled. When the first
flow amount control valve 7 is opened fully (100%), the second flow
amount control valve 12 is closed, while, when the second flow
amount control valve 12 is opened fully (100%), the first flow
amount control valve 7 is closed, that is, according to graph in
FIG. 2, the opening degree of the first flow amount control valve 7
(O.sub.M) and that of second flow amount control valve 12 (O.sub.B)
operate opposite to each other. A relationship between a flow
amount of the cooling water flowing through the main pipe 4
(F.sub.M) and that through the bypass pipe 11 (F.sub.B) in this
case is represented, for example, as in FIG. 3.
[0019] As described above, when both the first flow amount control
valve 7 and the second flow amount control valve 12 are provided in
the main pipe 4 and the bypass pipe 11, respectively, the maximum
flow amount (F.sub.MAX) of the cooling water is flowed into the
cooler 5 by setting O.sub.M=100% and O.sub.B=0%, whereby the
maximum performance of the cooling system including the pump 3 and
the cooler 5 can be utilized. In contrast, the main pipe 4 is
sealed off by setting O.sub.M=0% and O.sub.B=100% to flow the
cooling water only through the bypass pipe 11, whereby the cooler 5
can be maintained as well.
[0020] However, in order to obtain an effect according to the
present invention, the operation of each opening degree of the flow
amount control valves 7 and 12 is not limited to that represented
in FIG. 2, and not both the first flow amount control valve 7 and
the second flow amount control valve 12 are necessarily provided.
For example, even in a case of providing only the first flow amount
control valve 7, by controlling the opening degree O.sub.M as
represented in FIG. 4, the relationship between F.sub.M and F.sub.B
can be controlled. In this case, the main pipe 4 is sealed off by
setting O.sub.M=0%, whereby the cooler 5 can be maintained. Even in
a case of providing only the second flow amount control valve 12 is
provided, by controlling the opening degree O.sub.B as represented
in FIG. 5, the relationship between F.sub.M and F.sub.B can be
controlled. In this case, by setting O.sub.B=0%, the cooling water
can flow into the cooler 5 at the maximum flow amount
(F.sub.MAX).
[0021] As described above, if at least one of the first flow amount
control valve 7 placed along the main pipe 4 between both the
bifurcations 9 and 10 and the second flow amount control valve 12
placed along the bypass pipe 11 is provided, the relationship
between the flow amount of the cooling water flowing through the
main pipe 4 (F.sub.M) and that flowing through the bypass pipe 11
(F.sub.B) can be controlled. Accordingly, by varying a mixing ratio
between relatively cool cooling water circulating from the main
pipe 4 to the electrical device 2 through the cooler 5 and
relatively warm cooling water circulating from the bypass pipe 11
to the electrical device 2, the temperature of the water can be
controlled.
[0022] Here, in this embodiment, the configuration in which the
cooling water flowing through the main pipe 4 is divided by
providing the bypass pipe 11 is adopted; however, by providing only
the first flow amount control valve 7 at a position along the main
pipe 4 without providing such a flow-dividing circuit, and
narrowing the flow amount of the cooling water when the temperature
of the cooling water decreases, excessive temperature decrease of
the cooling water could also be prevented.
[0023] However, there are also many cases where the electrical
device 2 is high-voltage equipment; for example, because the front
and rear portions of the main pipe 4 where this electrical device 2
is arranged are configured of insulating material (such as
poly(tetrafluoroethylene)), the mechanical strength of the portions
are weak. If only the first flow amount control valve 7 is provided
at a position along the main pipe 4 as described above, the flow
amount can indeed be controlled; however, because
discharge-pressure control of the pump 3 is generally difficult, if
the opening degree of the first flow amount control valve 7 O.sub.M
is narrowed, water pressure increases. Accordingly, a problem
occurs whether the above described weak mechanical-strength portion
can resist the increased water pressure.
[0024] On the other hand, according to the water-cooled electrical
apparatus 1 relevant to this embodiment, because the bypass pipe 11
is provided as the flow-dividing circuit, even in a case of the
amount of cooling water flowing through the main pipe 4 being
reduced by the first flow amount control valve 7, a certain amount
of cooling water can flow through the bypass pipe 11, whereby
increase of the water pressure can be relaxed. Therefore, the
problem of the water-pressure resistance of the above weak
mechanical-strength portion can be resolved.
[0025] Next, operation procedures of the water-cooled electrical
apparatus 1 according to this embodiment represented in FIG. 1 are
explained. First, in a normal operation state in which the
cooling-water temperature T.sub.W measured by the water temperature
meter 8 is relatively high and cooling of the cooling water by the
cooler 5 is needed, the controller 14 controls the opening degrees
of the first flow amount control valve 7 and the second flow amount
control valve 12 so as to operate in an operation region R.sub.1
represented in FIG. 6. That is, in this operation region R.sub.1,
the control is performed so as to be the opening degree of the
first flow amount control valve 7 O.sub.M=100%, and that of the
second flow amount control valve 12 O.sub.B=0% whereby, by
circulating all of the cooling water to the cooler 5, the cooling
efficiency is maximized.
[0026] In a case in which outdoor temperature decreases and,
accompanying the decrease, the cooling-water temperature T.sub.W
measured by the water temperature meter 8 decreases, if the opening
degree of the first flow amount control valve 7 O.sub.M is kept at
100%, when cooling water that is overcooled flows into the indoor
area, dew condensation might occur depending on indoor humidity at
that time. In this case, the controller 14 operates to switch to an
operation region R.sub.2 represented in FIG. 6. In this operation
region R.sub.2, accompanying the decrease of the cooling-water
temperature T.sub.W, the controller 14 controls to decrease the
opening degree of the first flow amount control valve 7 O.sub.M
from 100% to 0%, and simultaneously increase the opening degree
O.sub.B from 0% to 100% according to FIG. 2. As described above, by
gradually decreasing the amount of the cooling water circulating to
the cooler 5, and simultaneously increasing the amount of the
relatively warm cooling water flowing through the bypass pipe 11,
unnecessary temperature decrease of the cooling water can be
prevented without powering on the heater 6.
[0027] In a case in which the cooling temperature T.sub.W further
decreases, the operation mode is set to a state in an operation
region R.sub.3 represented in FIG. 6, in which the controller 14
controls the opening degree of the first flow amount control valve
7 O.sub.M to keep 0%, and that of the second flow amount control
valve 12 O.sub.B to keep 100%, so that circulation to the cooler 5
placed outdoors is completely stopped. This means that, because the
indoor temperature also decreases accompanying the decrease of the
outdoor temperature, heat generation from the electrical device 2
can be balanced with only radiation heat from the main pipe 4 or
the bypass pipe 11 placed indoors. Thereby, temperature decrease of
the cooling water circulating indoors can be prevented, operating
time of the heater 6 placed can be minimized, and energy loss can
be reduced more than that of the conventional system.
[0028] Moreover, in a case in which the outdoor temperature further
decreases, and approaches to temperature T.sub.F at which the
cooling water freezes, the operation mode is set to a state in an
operation region R.sub.4 represented in FIG. 6, in which the
controller 14 controls the first flow amount control valve 7 so as
to secure the opening degree O.sub.M where the cooling water of a
minimum flow amount (F.sub.MIN) for preventing freezing can flow,
and simultaneously controls the second flow amount control valve 12
so as to slightly narrow the opening degree O.sub.B. Thereby, even
when the outdoor temperature decreases, the freezing of the cooling
water and breakage of the device caused by the freezing can be
prevented.
[0029] Boundary water temperatures T.sub.1, T.sub.2, and T.sub.3,
respectively between the above described operation regions R.sub.1
and R.sub.2, R.sub.2 and R.sub.3, and R.sub.3 and R.sub.4 may be
suitably determined, based on the heat generated by the electrical
device 2, the outdoor temperature, the indoor temperature, the
indoor humidity, and the following thermal-balance relational
equation, setting a goal that the amount of heat generated by the
heater is minimized while preventing dew condensation in the indoor
device.
Q.sub.E+Q.sub.H=Q.sub.C(T.sub.W,T.sub.O)+Q.sub.P1(T.sub.W,T.sub.O)+Q.sub-
.P2(T.sub.W,T.sub.I)
where [0030] Q.sub.E heat generated from the electrical device 2
[0031] Q.sub.H heat generated from the heater 6 [0032]
Q.sub.C(T.sub.W,T.sub.O) heat radiating from the cooler 5 [0033]
Q.sub.P1(T.sub.W,T.sub.O) heat radiating from the outdoor pipe
[0034] Q.sub.P2(T.sub.W,T.sub.I) heat radiating from the indoor
pipe, etc. [0035] T.sub.W cooling water temperature [0036] T.sub.O
outdoor temperature [0037] T.sub.I indoor temperature
[0038] Additionally, the freezing temperature of the cooling water
T.sub.F can also be lowered below 0 degree C. (for example,
approximately -30 degrees C.) by using conventional antifreeze
liquid (ethylene glycol, etc.).
[0039] As described above, according to the water-cooled electrical
apparatus 1 relevant to this embodiment, because the bypass pipe
11, and at least one of the first flow amount control valve 7
provided along the main pipe 4 between both the bifurcations 9 and
10 and the second flow amount control valve 12 provided along the
bypass pipe 11 are included, the water temperature can be
controlled by varying the mixing ratio between the relatively cold
cooling water circulating from the main pipe 4 to the electrical
device 2 through the cooler 5 and the relatively warm cooling water
circulating from the bypass pipe 11 to the electrical device 2.
Accordingly, because the temperature of the cooling water can be
controlled to be higher comparing to that of the conventional
system in which the entire amount of the cooling water circulating
through the cooling device, excessive temperature decrease of the
cooling water can be prevented, and energy loss by the heater can
be reduced.
[0040] In a case in which, as represented in FIG. 1, both the first
flow amount control valve 7 and the second flow amount control
valve 12 are provided, in addition to the above effect, the entire
amount of the cooling water can flow through the cooler 5;
therefore, an effect is also obtained in which the maximum
performance of this cooling system can be utilized, and maintenance
of the cooler 5 can be performed by sealing off the main pipe 4 at
the same time.
[0041] Moreover, the water temperature meter 8 for measuring the
water temperature of the cooling water flowing out from the cooler
5, and the controller 14 that receives a signal related to the
water temperature from the water temperature meter 8, and controls,
based on the signal, the opening degree of the first flow amount
control valve 7 or the second flow amount control valve 12 are
provided; therefore, the amount and the temperature of the cooling
water flowing through the main pipe 4 and the bypass pipe 11 can be
suitably controlled according to the measured temperature of the
cooling water, and the energy loss by the heater can be further
reduced.
Embodiment 2
[0042] In Embodiment 1, the example has been represented in which,
when the temperature of the cooling water approaches the
temperature T.sub.F at which the cooling water freezes, the amount
of the cooling water circulating through the cooler 5 is varied
stepwise up to F.sub.MIN by opening the first flow amount control
valve 7 having been closed. This embodiment is characterized in
that, instead of such stepwise variation, by gradually increasing
the opening degree O.sub.M of the first flow amount control valve 7
and decreasing the opening degree O.sub.B of the second flow amount
control valve 12, the flow amount through the main pipe 4 is slowly
varied to F.sub.MIN.
[0043] In Embodiment 1, because the first flow amount control valve
7 is opened stepwise at the time when the temperature of the
cooling water decreases to the predetermined level (T.sub.3),
increase of the water temperature by heating by the heater 6 cannot
catch up to decrease of the water temperature by the cooled water
flowing into the room at once, and thereby the electrical device 2
is transiently cooled, as a result, dew condensation might occur.
In contrast, in Embodiment 2, because the cooled water is mixed
thereinto with taking enough time from a stage before the
temperature of the cooling water has decreased to T.sub.3, which
can be compensated by increasing of the water temperature by
heating by the heater 6, an effect is also obtained that dew
condensation does not occur because the water temperature in the
room does not decrease so much.
EXPLANATION OF REFERENCES
[0044] 1: Water-cooled electrical apparatus [0045] 2: Electrical
device [0046] 3: Pump [0047] 4: Main pipe [0048] 5: Cooler [0049]
6: Heater [0050] 7: First flow amount control valve [0051] 8: Water
temperature meter [0052] 9: Bifurcation [0053] 10: Bifurcation
[0054] 11: Bypass pipe [0055] 12: Second flow amount control valve
[0056] 14: Controller
* * * * *