U.S. patent application number 13/601080 was filed with the patent office on 2013-03-28 for apparatus.
This patent application is currently assigned to ABB Research Ltd. The applicant listed for this patent is Bruno Agostini, Markku Elo, Mathieu Habert, Matti Kauranen. Invention is credited to Bruno Agostini, Markku Elo, Mathieu Habert, Matti Kauranen.
Application Number | 20130075076 13/601080 |
Document ID | / |
Family ID | 44582558 |
Filed Date | 2013-03-28 |
United States Patent
Application |
20130075076 |
Kind Code |
A1 |
Agostini; Bruno ; et
al. |
March 28, 2013 |
APPARATUS
Abstract
The disclosure relates to an apparatus including a first heat
transfer element having a base plate, with a first surface for
receiving an electric component and channels for transferring a
heat load received via the first surface into a fluid in the
channels, at least some of the channels protrude from a second
surface of the base plate, and a second heat transfer element for
receiving fluid from the first heat transfer element and passing a
heat load from said fluid to surroundings. In order to obtain an
efficient cooling, a phase change material is arranged at a second
surface of the base plate between at least two of the channels, the
phase change material absorbing heat by changing phase at a phase
change temperature during operation of the electric component.
Inventors: |
Agostini; Bruno; (Zurich,
CH) ; Habert; Mathieu; (Rheinfelden, CH) ;
Kauranen; Matti; (Espoo, FI) ; Elo; Markku;
(Espoo, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Agostini; Bruno
Habert; Mathieu
Kauranen; Matti
Elo; Markku |
Zurich
Rheinfelden
Espoo
Espoo |
|
CH
CH
FI
FI |
|
|
Assignee: |
ABB Research Ltd
Zurich
CH
|
Family ID: |
44582558 |
Appl. No.: |
13/601080 |
Filed: |
August 31, 2012 |
Current U.S.
Class: |
165/287 ;
165/67 |
Current CPC
Class: |
H05K 7/20945 20130101;
F28D 2020/0013 20130101; F28D 15/0275 20130101; H05K 7/20936
20130101; F28F 27/00 20130101; F28D 15/0266 20130101; F28D 20/02
20130101; Y02E 60/145 20130101; F28F 9/00 20130101; Y02E 60/14
20130101 |
Class at
Publication: |
165/287 ;
165/67 |
International
Class: |
F28F 9/00 20060101
F28F009/00; F28F 27/00 20060101 F28F027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 6, 2011 |
EP |
11180187.4 |
Claims
1. An apparatus comprising: a first heat transfer element including
a base plate, with a first surface for receiving an electric
component and channels for transferring a heat load received via
the first surface into a fluid in the channels, at least some of
the channels protruding from a second surface of the base plate; a
second heat transfer element for receiving fluid from the first
heat transfer element and for passing a heat load from the fluid to
the surroundings; and a phase change material arranged at the
second surface of the base plate between at least two of the
channels, the phase change material absorbing heat by changing
phase at a phase change temperature during the operation of said
electric component.
2. The apparatus according to claim 1, wherein the second heat
transfer element comprises: channels for receiving the fluid from
the first heat transfer element; and fins extending between the
channels for transferring the heat load to air passing between the
channels.
3. The apparatus according to claim 1, wherein the second heat
transfer element comprises: channels for receiving the fluid from
the first heat transfer element; and a cooling liquid passing
between the channels for transferring the heat load from the
channels to the passing cooling liquid.
4. The apparatus according to claim 1, comprising: a first manifold
arranged in the proximity of the first heat transfer element; a
second manifold, arranged in the proximity of the second heat
transfer element; the first and second manifolds connecting the
channels to each other at respective opposite ends of the channels;
wherein the channels extend between the first manifold and the
second manifold.
5. The apparatus according to claim 1, wherein the first heat
transfer element comprises fins extending between the channels.
6. The apparatus according to claim 1, wherein the channels are
arranged in pipes, the pipes are spaced apart and have internal
walls separating a plurality of channels from each other.
7. The apparatus according to claim 1, wherein the phase change
material is a material in which the heat absorption occurs during a
phase change from a solid state to a solid state.
8. The apparatus according to claim 1, wherein the phase change
material is arranged in a container.
9. The apparatus according to claim 1, wherein the phase change
material is arranged in a container comprising fins.
10. The apparatus according to claim 1, comprising: a temperature
sensor for measuring a temperature; an adjustable cooling
arrangement; and a controller, responsive to the temperature
sensor, for comparing the temperature measured with the temperature
sensor to a reference temperature, and for controlling the
adjustable cooling arrangement to reduce or increase cooling in
order for the measured temperature to reach the reference
temperature.
11. The apparatus according to claim 1, comprising: a temperature
sensor for measuring a temperature; and a controller, responsive to
the temperature sensor, for comparing the temperature measured with
the temperature sensor to a reference temperature, and for
controlling one or more electric components of the apparatus to
operate in a mode where they produce less heat when the measured
temperature is higher than the reference temperature.
12. The apparatus according to claim 10, wherein the temperature
sensor for measuring the temperature measures the temperature of an
electric component attached to the base plate, the temperature of
the base plate, the temperature of the phase change material or the
temperature of the second heat transfer element.
13. The apparatus according to claim 11, wherein the temperature
sensor for measuring the temperature measures the temperature of an
electric component attached to the base plate, the temperature of
the base plate, the temperature of the phase change material or the
temperature of the second heat transfer element.
14. The apparatus according to claim 1, in combination with a
frequency converter or inverter.
Description
RELATED APPLICATION(S)
[0001] This application claims priority under 35 U.S.C. .sctn.119
to European Patent Application No. 11180187.4 filed in Europe on
Sep. 6, 2011, the entire content of which is hereby incorporated by
reference in its entirety.
FIELD
[0002] This disclosure relates to an apparatus to be cooled, and to
a cooling solution for an apparatus including electric
components.
BACKGROUND INFORMATION
[0003] A known apparatus with a heat exchanger having a first heat
transfer element includes a base plate for an electric component,
and channels for transferring a heat load from the base plate into
fluid in the channels. The fluid can be passed on via the channels
to a second heat exchanger where the fluid can be cooled. At least
some of the channels protrude from a surface of the base plate.
[0004] The heat exchanger can have insufficient heat storage
capacity especially for handling temporary peaks in the amount of
heat generated by electric components.
SUMMARY
[0005] An apparatus is disclosed comprising a first heat transfer
element including a base plate, with a first surface for receiving
an electric component and channels for transferring a heat load
received via the first surface into a fluid in the channels, at
least some of the channels protruding from a second surface of the
base plate, a second heat transfer element for receiving fluid from
the first heat transfer element and for passing a heat load from
the fluid to the surroundings, and a phase change material arranged
at the second surface of the base plate between at least two of the
channels, the phase change material absorbing heat by changing
phase at a phase change temperature during the operation of said
electric component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] In the following, the present disclosure will be described
in closer detail by way of example and with reference to the
attached drawings, in which
[0007] FIGS. 1 to 2 illustrate a first exemplary embodiment of an
apparatus according to the disclosure;
[0008] FIG. 3 illustrates an exemplary embodiment of the apparatus
of FIGS. 1 and 2 with a phase change material;
[0009] FIG. 4 illustrates a temperature difference obtained with
the apparatus of FIGS. 1 and 2;
[0010] FIG. 5 illustrates a second exemplary embodiment of an
apparatus according to the disclosure; and
[0011] FIGS. 6 to 8 illustrate an effect of phase change material
at different ambient temperatures.
DETAILED DESCRIPTION
[0012] The use of a phase change material which during a phase
change absorbs heat can make it possible to obtain an apparatus
with more efficient cooling. Such a phase change material can be
arranged in a well-protected space between at least two channels in
order to temporarily provide a higher cooling capacity due to a
phase change of the material. Once there is no longer a need for a
higher cooling capacity and the temperature reaches a level below
the phase change temperature, the phase change material can return
to the original physical state in order for it to be ready to
absorb excess heat during a subsequent peak in the heat
generation.
[0013] In an exemplary embodiment, a cooling apparatus can be
adjusted in order to keep a temperature such that the phase change
material will work optimally.
[0014] FIGS. 1 to 2 illustrate a first exemplary embodiment of an
apparatus 1 according to the disclosure. The apparatus includes a
first heat transfer element 2 having a base plate 3 with a first
surface 4 for receiving one or more electric components that
require cooling during their use in order to avoid an excessive
temperature rise. The first heat transfer element 2 also includes a
plurality of channels 5 for transferring a received heat load into
a fluid circulating in the channels. From FIG. 2 it can be seen
that in this embodiment the channels 5 can be arranged in pipes 6,
which are spaced apart and have internal walls separating a
plurality of channels 5 from each other. The pipes can be MPE
(MultiPort Extruded) pipes which have been manufactured by
extruding aluminum, for example. In FIG. 1 the apparatus 1 is seen
from a direction where the base plate 3 is on top of the pipes 6
and FIG. 2 illustrates only some of the parts of the apparatus 1
seen from a direction where the pipes 6 are on top of the base
plate 3.
[0015] The apparatus includes a second heat transfer element 7,
which receives fluid from the first heat transfer element 2. In
this exemplary embodiment the pipes 6 extend all the way from a
first manifold 8 arranged in the proximity of the first heat
transfer element 2 to a second manifold 9 arranged in the proximity
of the second heat transfer element 7. The second heat transfer
element 7 includes the pipes 6 and fins 10 which extend between the
channels 5, in this case the walls of the pipes 6 containing the
channels. An airstream passing through the second heat transfer
element 7 can therefore transfer heat away from the fluid in the
pipes 6.
[0016] In the illustrated embodiment, the apparatus 1 can work as a
thermosyphon. The pipes 6 partly penetrate into the base plate 3
(working as an evaporator) such that some of the channels 5 located
in the pipes can be evaporator channels containing fluid that is
heated when the first heat transfer element 2 receives heat from an
electric component. The heated fluid (or possibly vapor at this
stage) flows towards the second heat transfer element 7 (working as
a condenser), where air passing between the channels 5 (located
inside the pipes 6) cools the fluid. The second manifold 9 can be
implemented as a tank, for example, a closed space with a fluid
connection to all channels 5 of the pipes 6. The fluid can
therefore exit the evaporator channels into the manifold and return
downwards towards the first manifold 8 via those channels 5 of the
pipes 6 that are located outside the base plate 3 and function as
condenser channels. The first manifold 8 can be implemented
similarly to the second manifold 9, for example, as a tank with a
fluid connection to each channel 5 of the pipes. Therefore, the
fluid entering the first manifold 8 via the condenser channels can
proceed via the evaporator channels to a new flow cycle. Such a
thermosyphon is advantageous as it can be utilized for cooling an
electric apparatus without a need for a pump to obtain the desired
fluid circulation.
[0017] An alternative to the illustrated embodiment can be to
separate the first and second heat transfer element 2 and 7 from
each other. In that case, the parallel channels 5 do not extend all
the way between the first and second heat transfer element 2 and 7.
Instead, an additional manifold can be arranged in the upper part
of the first heat transfer element 2 to receive fluid from all of
the channels 5 in the first heat transfer element 2. Similarly, a
second additional manifold can be arranged in the lower part of the
second heat transfer element 7 to pass fluid to all channels 5 of
the second heat transfer element 7. These additional manifolds can
be connected to each other with one or more pipes for passing fluid
from the first heat transfer element 2 (evaporator) to the second
heat transfer element 7 (condenser), and the second manifold 9 can
be connected to the first manifold 8 via one or more additional
pipes for returning the fluid from the second heat transfer element
7 (condenser) to the first heat transfer element 2
(evaporator).
[0018] Irrespective of which of the implementations is used for the
thermosyphon, the first heat transfer element 2 can be provided
with a phase change material 11 which during operation of the
apparatus enters a phase change to absorb heat in order to cool the
base plate 2 and one or more electric components attached to the
base plate. Such a phase change material 11 can be arranged against
a second surface 12 of the base plate 3, for example, substantially
over the entire surface area of the base plate 3. The second
surface 12 of the base plate 3 in the illustrated embodiment is
provided with channels 5 contained in pipes 6 and with fins 10
extending between these channels. However, there can be a lot of
empty spaces delimited by the second surface 12, the channels 5 and
the fins 10, and for example, as many of these empty spaces as
possible can be filled with the phase change material. In such an
arrangement, the phase change material can be efficiently
protected. Heat can be conducted directly from the base plate 3 to
the pipes 6 containing channels 5 and fluid, and in addition, from
the base plate 3 via the fins 10 to the pipes 6. In order to work
as efficiently as possible, the phase change material should be
located thermally closer to heat source than the "main" cooling
system is. In this way the phase change material reacts faster than
the main cooling system to temperature changes.
[0019] A Phase Change Material (PCM) can be a substance, which by
changing phase at a certain constant temperature, called phase
change temperature, is capable of storing and releasing large
amounts of energy at constant temperature. Phase change can occur
as melting and solidifying or as changes in the crystal structure
of materials where the phase change takes place from solid to
solid. Heat can be absorbed or released when the material changes
from one phase to another. Initially the temperature of a phase
change material 11 rises as the phase change material absorbs heat.
However, when a phase change material reaches a phase change
temperature at which it changes phase, it can absorb large amounts
of heat at a constant temperature until all material is transformed
to the new phase. When the ambient temperature around the material
subsequently falls, the phase change material can return to its
previous physical state, and release its stored latent heat.
[0020] A large number of phase change materials are available on
the market in any required temperature range, for example, from
114.degree. C. up to 1010.degree. C. A common type of phase change
materials is the solid-liquid. There are, however, other types of
phase change materials and some materials exhibit solid-solid phase
changes, in which the crystalline structure is altered at a certain
temperature. To be a useful PCM, a material should ideally meet
several criteria, release and absorb large amounts of energy when
freezing and melting, have a fixed and clearly determined phase
change temperature, remain stable and unchanged over many
freeze/melt cycles, be non-Hazardous, be economical, and should not
cause corrosion problems to other materials.
[0021] In the illustrated embodiment the apparatus 1 can be used in
an upright position, due to which a phase change material 11 with a
solid-solid phase change is desirable. Such a phase change material
11 can be inserted directly between the channels 5 and the fins 10
as illustrated in FIG. 2. Examples of suitable materials are salt
hydrates, fatty acids, esters, and various paraffins (such as
octadecane).
[0022] FIG. 3 illustrates an alternative for providing the
apparatus of FIGS. 1 and 2 with a phase change material.
[0023] In FIG. 3 a container 13 is used for encapsulating the phase
change material 11 before it is arranged in its place on the second
surface 12 of the base plate. This gives a greater freedom in
selecting a suitable phase change material. Solid-liquid phase
change materials, for example, can be used as the phase change
material and can be hermetically sealed. A suitable material to be
used in the embodiment of FIG. 3 can be, for example, salt hydrate,
such as PlusICE X80, available from Phase Change Material Products
Limited, for instance.
[0024] If solid-liquid material is used, the "container" can be
implemented to include the baseplate 3, the pipes 6 and a lid which
create a container or tank for the phase change material.
[0025] In the exemplary embodiment of FIG. 3, no fins 10 are
arranged at the location of the second surface 12 reserved for the
container 13. However, if it is advantageous to use fins 10 also in
connection with one or more containers 13 with phase change
material 11, then the fins 10 can be arranged inside the container
13 together with the phase change material 11. A container 13'
containing both phase change material 11 and fins 10 is also
illustrated in FIG. 3.
[0026] The fins 10 should be (thermally) attached to the base plate
4 via the second surface 12, so that the heat from the heat source
can come via baseplate 4 to fins 10 and further to the phase change
material. The fins 10 provide a good and even contact to the phase
change material, so that the heat distribution to the phase change
material is as even as possible.
[0027] Some of the available solid-solid phase change materials
have a very poor thermal conductivity, which means that the
effective thickness (=heat path) can be only a few millimeters. It
is desirable that the heat path from heat source to the phase
change material is as short as possible and the contact area to the
phase change material is as big as possible. The structure
described above utilizing fins to conduct heat from the base plate
into the phase change material is good from this point of view.
[0028] FIG. 4 illustrates the temperature difference obtained with
the apparatus of FIGS. 1 and 2.
[0029] FIG. 4 illustrates the temperature T (the temperature probe
is located on the surface 4 just below the heat source) at
different moments of time t (seconds) when the apparatus of FIG. 1
is used for removing heat from electronic components of a frequency
converter (can be used other electric devices too), for example, a
drive used for controlling the speed of an electric motor, for
instance. The ambient temperature has been selected to be optimal
for the phase change material in question, in this case 40.degree.
C. Curve B illustrates the temperature behavior when no phase
change material is in use, and the curve A illustrates the
temperature behavior when the spaces between the channels 5, the
fins 10 and the second surface 12 of the base plate are filled with
a phase change material. In this case, the temperature peak is
reduced (.DELTA.T) by about 6.4.degree. C.
[0030] For semiconductor components, for example, a reduction of
the temperature change can have a significant impact on the
expected lifetime of the component in question. Practical tests
have shown that when temperature peaks occur cyclically, a
reduction of the temperature change during the peak from 30.degree.
C. to 25.degree. C. increases the number of cycles without
malfunctions by about 4 to 5 times.
[0031] Also the peak temperature will be lower (in this example
from 77-71.degree. C.), which also makes the lifetime longer.
[0032] FIG. 5 illustrates a second exemplary embodiment of an
apparatus 1'. The apparatus 1' is very similar to the one explained
in connection with FIGS. 1 and 2. Therefore the embodiment of FIG.
5 will mainly be explained by pointing out the differences between
these embodiments.
[0033] In FIG. 5, a similar apparatus, for example, thermosyphon
with a base plate 3, a second heat transfer element 7, channels 5
and manifolds 8 and 9 is used as in FIG. 1. The second surface of
the base plate (not shown in FIG. 5) can also be provided with a
phase change material.
[0034] Phase change materials can be efficiently utilized at an
ambient temperature which is dependent on the selected material in
question. Each phase change material has a different phase change
temperature and can be selected depending on the application.
Properties and the amount of phase change material is always
dependent on the design (system), heat load, allowed temperatures
and cooling conditions (ambient temperature or cooling
temperature). To achieve the best results, the phase change
temperature of the phase change material should be selected
accordingly.
[0035] The best results in using a phase change material can be
obtained by ensuring that the ambient temperature is optimal for
the selected phase change material. FIG. 5 illustrates two
alternatives that can be used simultaneously or independently of
each other for ensuring that the ambient temperature is optimal. In
both alternatives a temperature sensor 14 can be utilized for
measuring the ambient temperature and information about the ambient
temperature is provided to a controller 15, which may be
implemented with circuitry or as a combination of circuitry and a
computer program. In many cases the controller is integrated to
circuitry of electric device, so that it does not require any extra
components and/or printed circuit boards. In these cases the
functionality is done with software.
[0036] The controller can also be implemented by at least one
processor (e.g., general purpose or application specific) or a
computer processing device which is configured to execute a
computer program tangibly recorded on a non-transitory
computer-readable recording medium, such as a hard disk drive,
flash memory, optical memory or any other type of non-volatile
memory. Upon executing the program, the at least one processor is
configured to perform the operative functions of the
above-described exemplary embodiments.
[0037] The temperature sensor 14 can be attached to an electric
component 16, the base plate 3, the phase change material or the
second heat transfer element 7. In general, the temperature sensor
should desirably be placed as close to the actual heat source as
possible in order to detect changes as fast as possible. The
controller receives information about the measured temperature,
which is used by the controller 15 to determine if the measured
temperature is above or below a reference temperature (the optimal
ambient temperature for the selected phase change material in
question).
[0038] The first alternative is that the controller 15 adjusts the
cooling efficiency in order to try to maintain the ambient
temperature at the optimal level. In that case, an adjustable fan
17 may be utilized, for instance, in order to increase or decrease
the amount of air flowing through the second heat transfer element
7. If the measured temperature is too high, the speed of the fan 17
is increased, and if the measured temperature is too low, the speed
of the fan 17 is reduced. Depending on the practical
implementation, other types of adjustable cooling may be employed,
in which case the adjustment can affect the speed of a pump or the
position of a valve regulating a flow, for instance. If a pump is
utilized the cooling media flowing between the channels of the
second heat transfer element may be a suitable liquid such as
water, for instance.
[0039] The second alternative is that the controller 15 adjusts the
amount of heat produced by the electric component 16. In that case,
the controller 15 controls the electric component or components to
operate in a mode (at a lower efficiency level, for example) where
they produce less heat during periods when the measured temperature
is too high. In the case of a frequency converter, for example,
this might lead to a situation where the entire potential of the
frequency converter cannot be utilized during such periods but
permanent damage to the components of the frequency converter can
in any case be avoided. The use of the phase change material can
make it possible to allow a bigger heat peak than in solutions
without the phase change material.
[0040] FIGS. 6 to 8 illustrate the effect of phase change material
at different temperatures. FIGS. 6 to 8 are similar to FIG. 4. Thus
they illustrate the temperature T at different moments of time t
(seconds) when the apparatus of FIG. 1 is used for removing heat
from electronic components. Curve B illustrates the temperature
behavior when no phase change material is in use, and the curve A
illustrates the temperature behavior when the spaces between
channels 5, the fins 10 and the second surface 12 of the base plate
are filled with a phase change material. The used phase change
material is the same in FIGS. 4 and 6 to 8.
[0041] In the case of FIG. 4, the exemplary ambient temperature was
selected to be optimal for the phase change material, for example
40.degree. C. In that case, the temperature peak was reduced
(.DELTA.T) by about 6.4.degree. C. when phase change material was
in use.
[0042] In the case of FIG. 6, the exemplary ambient temperature is
no longer optimal, but instead 30.degree. C. In that case, the
temperature peak was reduced (.DELTA.T) by about 1.2.degree. C.
when phase change material was in use.
[0043] In the case of FIG. 7, the exemplary ambient temperature is
35.degree. C. In that case, the temperature peak was reduced
(.DELTA.T) by about 3.9.degree. C. when phase change material was
in use.
[0044] In the case of FIG. 8, the exemplary ambient temperature is
45.degree. C. As can be seen from FIG. 8, the phase change material
changes phase early at this temperature, and after about 75 seconds
the phase change has already taken place.
[0045] Based on a comparison of FIGS. 4 and 6 to 8 it is clear that
in order to work efficiently, the phase change material desirably
should be used at an ambient temperature optimal for the material
in question, otherwise there is not much sense in utilizing phase
change material at all. Based on this discovery, it is clear that a
solution where the "main" cooling system is adjusted in order to
keep the temperature at a suitable level for the phase change
material, as explained in connection with FIG. 5, can be
advantageous, because then once a peak occurs in the heat
generation, the phase change material can work efficiently and
quickly to reduce the negative impact such a peak can have on the
apparatus in question. If the pump (and liquid) is used instead of
the fan (and air), there is analogue from ambient temperature to
coolant (e.g. water) temperature.
[0046] It is to be understood that the above description and the
accompanying figures are only intended to illustrate the present
disclosure. It will be obvious to a person skilled in the art that
the disclosure can be varied and modified without departing from
the scope of the disclosure.
[0047] Thus, it will be appreciated by those skilled in the art
that the present invention can be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The presently disclosed embodiments are therefore
considered in all respects to be illustrative and not restricted.
The scope of the invention is indicated by the appended claims
rather than the foregoing description and all changes that come
within the meaning and range and equivalence thereof are intended
to be embraced therein.
* * * * *