U.S. patent application number 13/872452 was filed with the patent office on 2013-09-12 for heat exchanger and magnetic refrigeration system.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA. Invention is credited to Shiori KAJI, Tadahiko KOBAYASHI, Akiko SAITO.
Application Number | 20130232993 13/872452 |
Document ID | / |
Family ID | 45993338 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130232993 |
Kind Code |
A1 |
SAITO; Akiko ; et
al. |
September 12, 2013 |
HEAT EXCHANGER AND MAGNETIC REFRIGERATION SYSTEM
Abstract
According to one embodiment, a heat exchanger includes a
container, and a plurality of heat exchange components. The
container is fed with a heat transport medium. The plurality of
heat exchange components is provided with a prescribed spacing
inside the container. The plurality of heat exchange components is
provided along a flowing direction of the heat transport medium so
as not to overlap at least partly as viewed in the flowing
direction of the heat transport medium.
Inventors: |
SAITO; Akiko; (Kanagawa-ken,
JP) ; KOBAYASHI; Tadahiko; (Kanagawa-ken, JP)
; KAJI; Shiori; (Kanagawa-ken, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA |
Minato-ku |
|
JP |
|
|
Assignee: |
Kabushiki Kaisha Toshiba
Minato-ku
JP
|
Family ID: |
45993338 |
Appl. No.: |
13/872452 |
Filed: |
April 29, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2010/069376 |
Oct 29, 2010 |
|
|
|
13872452 |
|
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Current U.S.
Class: |
62/3.1 ;
165/80.1 |
Current CPC
Class: |
F25B 21/00 20130101;
Y02B 30/66 20130101; F28F 13/003 20130101; F25B 2321/002 20130101;
F28F 13/06 20130101; Y02B 30/00 20130101 |
Class at
Publication: |
62/3.1 ;
165/80.1 |
International
Class: |
F25B 21/00 20060101
F25B021/00 |
Claims
1. A heat exchanger comprising: a container to be fed with a heat
transport medium; and a plurality of heat exchange components
provided with a prescribed spacing inside the container, the
plurality of heat exchange components being provided along a
flowing direction of the heat transport medium so as not to overlap
at least partly as viewed in the flowing direction of the heat
transport medium.
2. The heat exchanger according to claim 1, wherein a gap between
the heat exchange components provided on a front side in the
flowing direction of the heat transport medium is obstructed by the
heat exchange component provided on a back side in the flowing
direction of the heat transport medium.
3. The heat exchanger according to claim 1, wherein the plurality
of heat exchange components include a magnetocaloric effect
material.
4. The heat exchanger according to claim 3, wherein one of the
plurality of heat exchange components is formed from the
magnetocaloric effect material different from that of another of
the plurality of heat exchange components.
5. The heat exchanger according to claim 3, wherein the plurality
of heat exchange components are divided into multiple areas between
the upstream side and the downstream side in the heat exchanger and
each area is formed from the magnetocaloric effect material
different from each other.
6. The heat exchanger according to claim 3, wherein the
magnetocaloric effect material includes at least one selected from
the group consisting of Gd (gadolinium), a Gd compound, an
intermetallic compound made of some rare earth elements and
transition metal elements, a Ni.sub.2MnGa alloy, a GdGeSi compound,
a LaFe.sub.13-based compound, and LaFe.sub.13H.
7. The heat exchanger according to claim 1, wherein the container
has a circular cross-sectional shape or a rectangular
cross-sectional shape as viewed in the flowing direction of the
heat transport medium.
8. The heat exchanger according to claim 1, wherein the container
has a cylindrical shape or a rectangular tubular shape.
9. The heat exchanger according to claim 1, wherein the plurality
of heat exchange components are provided parallel to each
other.
10. The heat exchanger according to claim 1, wherein the plurality
of heat exchange components are provided in a staggered
lattice.
11. The heat exchanger according to claim 1, wherein the heat
exchange components have a strip shape, and ratio of shortest side
to longest side of the strip shape is 1:4 or more.
12. The heat exchanger according to claim 1, wherein the heat
exchange components have a strip shape, and ratio of shortest side
to longest side of the strip shape is 1:7 or more.
13. The heat exchanger according to claim 1, wherein
cross-sectional shape of the plurality of heat exchange components
is at least one selected from the group consisting of polygon,
circle, and ellipse.
14. The heat exchanger according to claim 1, wherein arrangement
pitch of the plurality of heat exchange components provided on both
end sides of the container is smaller than arrangement pitch of the
plurality of heat exchange components provided on a center side of
the container.
15. The heat exchanger according to claim 1, wherein the at least
some heat exchange components are connected to each other at one
end portion.
16. The heat exchanger according to claim 5, wherein the
magnetocaloric effect material is selected based on Curie
temperature.
17. A magnetic refrigeration system comprising: the heat exchanger
according to claim 1; a magnetic field changing section configured
to change a strength of applied magnetic field to the heat
exchanger; and a heat transport section configured to feed the heat
exchanger with the heat transport medium.
18. The system according to claim 17, a longest side of a heat
exchange components is provided parallel to a direction of magnetic
field.
19. The system according to claim 17, wherein the magnetic field
changing section includes a permanent magnet.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application of International
Application PCT/JP2010/069376, filed on Oct. 29, 2010; the entire
contents of which are incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate generally to a heat
exchanger and a magnetic refrigeration system.
BACKGROUND
[0003] Recently, as an environment-conscious and efficient
refrigeration technology, the magnetic refrigeration technology
using the magnetocaloric effect has been raising expectations and
activating research and development. In the magnetic refrigeration
technology, a magnetic refrigeration cycle is configured using the
magnetocaloric effect to produce a high temperature section and a
low temperature section.
[0004] As one of such magnetic refrigeration technologies, the
refrigeration technology called the AMR (active magnetic
regenerative refrigeration) technique is proposed. In the AMR
technique, the magnetic refrigeration operation using the
magnetocaloric effect is performed by a heat exchange component
including a magnetocaloric effect material. Simultaneously, the
cold heat generated by this magnetic refrigeration operation is
stored in that component.
[0005] The AMR technique can achieve a higher heat exchange
efficiency than the gas refrigeration technology using the gas
compression-expansion cycle.
[0006] However, from the viewpoint of energy saving and the like,
further improvement in heat exchange efficiency has been
desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGS. 1A and 1B are schematic sectional views for
illustrating a heat exchanger according to a first embodiment;
[0008] FIGS. 2A to 2C are schematic sectional views for
illustrating heat exchangers according to comparative examples;
[0009] FIGS. 3A to 3C are schematic sectional views for
illustrating the arrangement of heat exchange components;
[0010] FIGS. 4A to 4E are schematic sectional views for
illustrating the cross-sectional shape in the plane parallel to the
xy plane of the heat exchange component;
[0011] FIGS. 5A and 5B are schematic views for illustrating the
turbulent state occurring in the flow of the heat transport medium
20;
[0012] FIGS. 6A and 6B are schematic views for illustrating the
arrangement configuration of the heat exchange components;
[0013] FIGS. 7A and 7B are graphs for illustrating the comparison
between the amount of heat exchange of the practical example and
the amount of heat exchange of the comparative example;
[0014] FIGS. 8A to 8D are schematic views for illustrating a method
for arranging the heat exchange components;
[0015] FIGS. 9A to 9D are also schematic views for illustrating a
method for arranging the heat exchange components;
[0016] FIGS. 10A and 10B are also schematic views for illustrating
a method for arranging the heat exchange components;
[0017] FIGS. 11A and 11B are schematic sectional views for
illustrating cases of arranging heat exchange components formed
from different magnetocaloric effect materials;
[0018] FIG. 12 is a schematic configuration view for illustrating a
magnetic refrigeration system according to a second embodiment;
and
[0019] FIG. 13 is a schematic line diagram of the magnetic
refrigeration system according to the second embodiment.
DETAILED DESCRIPTION
[0020] In general, according to one embodiment, a heat exchanger
includes a container, and a plurality of heat exchange
components.
[0021] The container is fed with a heat transport medium.
[0022] The plurality of heat exchange components is provided with a
prescribed spacing inside the container.
[0023] The plurality of heat exchange components is provided along
a flowing direction of the heat transport medium so as not to
overlap at least partly as viewed in the flowing direction of the
heat transport medium.
[0024] Embodiments will now be illustrated with reference to the
drawings. In the drawings, similar components are labeled with like
reference numerals, and the detailed description thereof is omitted
appropriately.
[0025] In the drawings, arrows x, y, and z indicate three
directions (axes) orthogonal to each other. The z direction is
taken as the direction of magnetic field.
[0026] The flowing direction of the heat transport medium 20 may be
directed in the y direction or the direction opposite to the y
direction during the operation of the magnetic refrigeration
system. As an example, the case of the heat transport medium 20
flowing in the y direction will be illustrated.
First Embodiment
[0027] FIGS. 1A and 1B are schematic sectional views for
illustrating a heat exchanger according to a first embodiment.
FIGS. 2A to 2C are schematic sectional views for illustrating heat
exchangers according to comparative examples. Here, FIG. 2A is a
schematic sectional view of a heat exchanger provided with
spherical heat exchange components including a magnetocaloric
effect material. FIGS. 2B and 2C are schematic sectional views of a
heat exchanger provided with plate-like heat exchange components
including a magnetocaloric effect material.
[0028] FIGS. 3A to 3C are schematic sectional views for
illustrating the arrangement of heat exchange components.
[0029] First, heat exchangers according to comparative examples are
illustrated.
[0030] FIG. 2A is a schematic sectional view for illustrating a
heat exchanger according to a first comparative example.
[0031] As shown in FIG. 2A, the heat exchanger (ARM bed) 50
includes a container 51, heat exchange components 52, and a
partition 53.
[0032] The container 51 is configured as a tube having a
rectangular cross-sectional shape as viewed in the y direction.
[0033] The heat exchange component 52 has a spherical shape and is
configured to include a magnetocaloric effect material such as Gd
(gadolinium). The heat exchange components 52 are packed inside the
container 51 with a packing ratio of 60% or more.
[0034] The partition 53 is shaped like a mesh and provided near
both end portions of the container 51. The mesh size of the
partition 53 is made smaller than the size of the heat exchange
component 52 so as to prevent the heat exchange component 52 from
dropping out of the container 51. The heat exchanger 50 is
configured so that a heat transport medium 20 is fed into the
container 51 through one partition 53, and the fed heat transport
medium 20 is ejected out of the container 51 through the other
partition 53. The feed and ejection of the heat transport medium 20
to the container 51 from one direction, and the feed and ejection
of the heat transport medium 20 to the container 51 from the
opposite direction, constitute one magnetic refrigeration
cycle.
[0035] Here, if the particle diameter of the heat exchange
component 52 is made small, the heat exchange components 52 can be
packed inside the container 51 with a high packing ratio and a
large surface area. In this case, as the packing ratio becomes
higher, the amount of heat generated by the magnetic refrigeration
work becomes larger. As the surface area becomes larger, the
generated heat can be passed (heat-exchanged) more efficiently to
the heat transport medium 20.
[0036] However, in the case where the frequency of the magnetic
refrigeration cycle is made higher (the number of magnetic
refrigeration cycles per unit time is increased) to increase the
refrigeration power, the pressure loss of the heat transport medium
20 is increased with the increase of the frequency. This may
decrease the refrigeration performance, or hamper the operation of
the magnetic refrigeration system including the heat exchanger
50.
[0037] More specifically, in the heat exchanger 50 packed with
spherical heat exchange components 52, in the case where the
particle diameter is small, the pressure loss is increased with the
increase of the frequency. This may make difficult the operation of
the magnetic refrigeration system including the heat exchanger 50.
On the other hand, in the case where the particle diameter is
large, the pressure loss can be reduced. However, due to the
decrease of the surface area, the heat exchange efficiency
decreases and may incur the decrease of the refrigeration
performance.
[0038] FIGS. 2B and 2C are schematic sectional views for
illustrating a heat exchanger according to a second comparative
example.
[0039] As shown in FIGS. 2B and 2C, the heat exchanger (ARM bed) 60
includes a container 51 and heat exchange components 62.
[0040] The heat exchange component 62 has a plate-like shape and is
configured to include a magnetocaloric effect material such as Gd
(gadolinium). The heat exchange components 62 are provided in a
plurality inside the container 51. The space between the heat
exchange components 62 and between the heat exchange component 62
and the inner wall of the container 51 constitutes the channel of
the heat transport medium 20.
[0041] Thus, the plate-like heat exchange components 62 are
provided parallel to the flow of the heat transport medium 20. This
can reduce the pressure loss of the heat transport medium 20.
Accordingly, the frequency of the magnetic refrigeration cycle can
be increased.
[0042] However, the heat transport medium 20 fed into the container
51 flows at high speed in a portion having low flow resistance
between the heat exchange components 62 and between the heat
exchange component 62 and the inner wall of the container 51. Thus,
if the frequency of the magnetic refrigeration cycle is increased,
the heat exchange efficiency between the heat exchange component 62
and the heat transport medium 20 is decreased. This may decrease
the refrigeration performance.
[0043] Furthermore, the magnetic refrigeration system based on the
AMR technique is operated with a temperature gradient formed
between both ends (high temperature end and low temperature end) of
the heat exchanger. More specifically, a temperature gradient is
formed by the heat storage effect of the heat exchange component
including the magnetocaloric effect material. In the state in which
the temperature gradient is formed, the operation is performed.
Thus, heat generation at the high temperature end and heat
absorption at the low temperature end are utilized. Accordingly, it
is necessary to produce a large temperature difference between the
high temperature end and the low temperature end and to stably
maintain the temperature gradient formed between both ends. The
temperature gradient formed can be stably maintained by decreasing
the thermal conductivity between the portion of the heat exchange
component 62 located on the high temperature end side and the
portion of the heat exchange component 62 located on the low
temperature end side.
[0044] However, in the plate-like heat exchange component 62, the
portion located on the high temperature end side and the portion
located on the low temperature end side are integrated. This
results in high thermal conductivity. Next, returning to FIGS. 1A
and 1B and FIGS. 3A to 3C, the heat exchanger according to the
first embodiment is illustrated.
[0045] As shown in FIGS. 1A and 1B, the heat exchanger (ARM bed) 1
includes a container 11 to be fed with a heat transport medium 20,
and heat exchange components 12.
[0046] The container 11 can be configured as a tube having a
rectangular cross-sectional shape as viewed in the y direction.
However, the cross-sectional shape as viewed in the y direction is
not limited to a rectangle, but can be appropriately modified.
[0047] For instance, by using a cylindrical container having a
circular cross-sectional shape as viewed in the y direction, the
pressure in the container can be isotropically distributed.
Furthermore, a cylindrical container is preferable also from the
viewpoint of the heat exchange efficiency between the heat exchange
component 12 in contact with the container inner wall and the heat
transport medium 20. In the case of a tube having a rectangular
cross-sectional shape, the heat exchange efficiency between the
heat transport medium 20 and the heat exchange component 12 is made
lower at the corners than at the tube center portion. However, a
cylindrical container can improve this situation.
[0048] The heat exchange component 12 is configured to include a
magnetocaloric effect material. Examples of the magnetocaloric
effect material can include Gd (gadolinium), Gd compounds of Gd
(gadolinium) mixed with some elements, intermetallic compounds made
of some rare earth elements and transition metal elements,
Ni.sub.2MnGa alloys, GdGeSi compounds, LaFe.sub.13-based compounds,
and LaFe.sub.13H. However, the magnetocaloric effect material is
not limited to those illustrated. Any material developing the
magnetocaloric effect can be appropriately selected.
[0049] The heat exchange components 12 are provided in a plurality
with a prescribed spacing inside the container 11. The heat
exchange components 12 are arranged parallel to each other inside
the container 11. The longest side 12a of the heat exchange
component 12 is directed parallel to the direction of the magnetic
field (z direction). One side 12b in the plane perpendicular to the
longest side 12a is directed parallel to the y direction. As
illustrated in FIG. 1A and FIGS. 3A to 3C, the plurality of heat
exchange components 12 are provided along the flowing direction of
the heat transport medium 20 so as not to overlap at least partly
as viewed in the flowing direction (y direction) of the heat
transport medium 20.
[0050] In this description, the flowing direction of the heat
transport medium 20 refers to the streamline of the heat transport
medium 20 in the container 11, and not to the feeding direction of
the heat transport medium 20 into the container 11.
[0051] Here, the streamline is defined as follows. The y-direction
center point is denoted by (Y0, x). The y-direction end points (the
points in contact with the wall surface of the container 11) at the
same x position as (Y0, x) are denoted by (Yr, x) and (Y-r, x). The
trajectory of the point at which the distance to (Y0, x) and the
distance to (Yr, x) are equal is denoted by line L1. The trajectory
of the point at which the distance to (Y0, x) and the distance to
(Y-r, x) are equal is denoted by line L2. Then, the streamline is
defined as lines L1 and L2. For instance, in the case where the
container 11 has a rectangular cross section as shown in FIGS. 1A
and 1B, then L1 and L2 are parallel to the x-axis direction.
[0052] In this case, as illustrated in FIG. 1A and FIGS. 3A to 3C,
the heat exchange components 12 can be arranged in a staggered
lattice in the plane parallel to the xy plane. However, the
embodiment is not limited to the arrangement in a staggered
lattice. The arrangement pitch of the heat exchange components 12
may be made different for each column, or the arrangement pitch of
the heat exchange components 12 may be changed in one column.
[0053] Furthermore, as shown in FIGS. 1A and 3B, the heat exchange
components 12 can be arranged so that the dimension d between the
heat exchange components 12 in the x direction is related to the
dimension a of the heat exchange component 12 in the same direction
as d.ltoreq.a.
[0054] Furthermore, a plurality of columns having such a
dimensional relation can be arranged in the y direction with a gap
between the columns.
[0055] Furthermore, the columns adjacent in the y direction can be
configured so that the heat exchange components 12 in the
respective columns have a complementary relation to the gap 12c
between the heat exchange components 12. More specifically, as
viewed in the y direction, the gap 12c between the heat exchange
components 12 located in the forward column can be obstructed by a
heat exchange component 12 located in the backward column.
Furthermore, as viewed in the y direction, the gap 12c between the
heat exchange components 12 located in the backward column can be
obstructed by a heat exchange component 12 located in the forward
column.
[0056] That is, the gap 12c between the heat exchange components 12
provided on the front side in the flowing direction of the heat
transport medium 20 is obstructed by a heat exchange component 12
provided on the back side in the flowing direction of the heat
transport medium 20.
[0057] In this description, being parallel includes not only being
completely parallel, but also an error range in which the function
and effect described later can be substantially achieved.
Furthermore, being perpendicular includes not only being completely
perpendicular, but also an error range in which the function and
effect described later can be substantially achieved.
[0058] The arrangement configuration of the heat exchange
components 12 as described above can form many turbulent portions
when the heat transport medium 20 flows inside the container 11.
This can increase the heat transport medium 20 contributing to heat
exchange near the heat exchange components 12. As a result, the
heat exchange efficiency between the heat exchange component 12 and
the heat transport medium 20 can be improved. The details on the
turbulent state occurring in the flow of the heat transport medium
20 will be described later.
[0059] The heat exchange components 12 are arranged parallel to the
y direction. This can suppress the pressure loss of the heat
transport medium 20 during the operation of the magnetic
refrigeration system.
[0060] The longest side 12a of the heat exchange component 12 is
directed parallel to the direction of the magnetic field (z
direction). This can suppress the influence of the demagnetizing
field when a magnetic field is applied to the heat exchange
component 12. Thus, the effective magnetic field can be enhanced.
Accordingly, a magnetic refrigeration system with high
refrigeration performance can be provided.
[0061] In this case, in order to enhance the effective magnetic
field, a higher aspect ratio of the heat exchange component 12 is
more favorable. For instance, in the case where the heat exchange
component 12 is shaped like a strip, the ratio of the shortest side
to the longest side (the side in the z direction) can be set to 1:4
or more, and more preferably 1:7 or more.
[0062] Next, the cross-sectional shape in the plane parallel to the
xy plane of the heat exchange component is illustrated. FIGS. 4A to
4E are schematic sectional views for illustrating the
cross-sectional shape in the plane parallel to the xy plane of the
heat exchange component.
[0063] The cross-sectional shape in the plane parallel to the xy
plane of the heat exchange component 12 illustrated in FIG. 1A and
FIGS. 3A to 3C is a rectangle, but is not limited thereto.
[0064] For instance, as illustrated in FIG. 4A, the cross-sectional
shape in the plane parallel to the xy plane of a heat exchange
component 22 can be a square.
[0065] Furthermore, as illustrated in FIG. 4B, the cross-sectional
shape in the plane parallel to the xy plane of a heat exchange
component 23 can be a triangle. In this case, in view of possible
change in the flowing direction of the heat transport medium 20
during the operation of the magnetic refrigeration system, the
orientations of the heat exchange component 23a and the heat
exchange component 23b can be made different. For instance, as
illustrated in FIG. 4B, the heat exchange component 23a can be
arranged so that its vertex is directed to the direction opposite
to the y direction, and the heat exchange component 23b can be
arranged so that its vertex is directed to the y direction.
[0066] Furthermore, as illustrated in FIG. 4C, the cross-sectional
shape in the plane parallel to the xy plane of a heat exchange
component 24 can be a hexagon.
[0067] Furthermore, as illustrated in FIG. 4D, the cross-sectional
shape in the plane parallel to the xy plane of a heat exchange
component 25 can be a circle.
[0068] The cross-sectional shape in the plane parallel to the xy
plane of the heat exchange component is not limited to those
illustrated, but can be appropriately modified. For instance, other
polygons such as pentagon can also be used, and an ellipse and the
like can also be used. Furthermore, for instance, a shape formed
from an arbitrary curve, or a shape formed from an arbitrary curve
and an arbitrary straight line can also be used.
[0069] In this case, in the case of having a quadrangular
cross-sectional shape like the heat exchange components 12, 22, the
pressure loss of the heat transport medium 20 can be suppressed at
a low level. Furthermore, many turbulent portions can be formed
when the heat transport medium 20 flows inside the container 11.
This can increase the heat transport medium 20 contributing to heat
exchange near the heat exchange components 12, 22. As a result, the
heat exchange efficiency between the heat exchange component 12, 22
and the heat transport medium 20 can be improved.
[0070] Furthermore, the shape processing of the heat exchange
component 12, 22 is simplified. This enables manufacturing of the
heat exchange component 12, 22 with high accuracy. Furthermore, the
workability of arranging the heat exchange components 12, 22 inside
the container 11 can be improved.
[0071] Furthermore, a cross-sectional shape having a smoother
outline, such as a hexagonal cross-sectional shape like the heat
exchange component 24 and a circular cross-sectional shape like the
heat exchange component 25, can suppress the pressure loss of the
heat transport medium 20 at a lower level. For instance, a
cross-sectional shape having a smoother outline can be selected for
a heat transport medium 20 having a higher viscosity.
[0072] Furthermore, as described later, a stable turbulent state
can be formed between the heat exchange components. This can
increase the heat transport medium 20 contributing to heat exchange
near the heat exchange components. Furthermore, heat exchange
components having a smooth cross-sectional shape with an angle of
90 degrees or more or a rounded outline can smooth the flow line of
the heat transport medium 20. This can suppress the dead volume
(the volume of the heat transport medium 20 contributing less to
heat exchange) at a lower level. As a result, the heat exchange
efficiency between the heat exchange component and the heat
transport medium 20 can be improved.
[0073] Furthermore, it is also possible to arrange heat exchange
components different in cross-sectional shape, cross-sectional
area, and arrangement pitch.
[0074] For instance, as illustrated in FIG. 4E, heat exchange
components 12 and heat exchange components 22 different in
cross-sectional shape, cross-sectional area, and arrangement pitch
can be arranged.
[0075] In this case, the arrangement pitch of the heat exchange
components 22 provided on the inflow side of the heat transport
medium 20 in the container 11 can be made smaller than the
arrangement pitch of the heat exchange components 12. Then, the
pressure loss in the region provided with the heat exchange
components 22 can be made higher than the pressure loss in the
region provided with the heat exchange components 12. This can
rectify the flow of the heat transport medium 20, which is made
uneven upon flowing from the piping into the container 11. After
the inflow, the pressure loss can be reduced by the heat exchange
components 12 having a larger arrangement pitch. In this case, in
view of possible change in the flowing direction of the heat
transport medium 20 during the operation of the magnetic
refrigeration system, the heat exchange components 22 having a
small arrangement pitch can be provided on both end sides of the
container 11.
[0076] The shape, dimension, arrangement configuration (such as
arrangement pitch and position), number and the like of the heat
exchange components can be appropriately modified depending on e.g.
the viscosity of the heat transport medium 20 and the operating
temperature of the magnetic refrigeration system.
[0077] Next, the turbulent state occurring in the flow of the heat
transport medium 20 is further illustrated.
[0078] FIGS. 5A and 5B are schematic views for illustrating the
turbulent state occurring in the flow of the heat transport medium
20.
[0079] FIG. 5A shows the case where the heat exchange components 25
having a circular cross-sectional shape are arranged in a regular
lattice. FIG. 5B shows the case where the heat exchange components
25 having a circular cross-sectional shape are arranged in a
staggered lattice.
[0080] It is assumed that the heat transport medium 20 flows at the
same flow rate in a space of the same volume. The flow velocity
distribution is shown with monotone shading. In the gap 201, the
flow velocity v is faster than a threshold vc. The gap 201 is
represented by a dark shade. In the gap 202, the flow velocity v is
slower than the threshold vc. The gap 202 is represented by a light
shade. In FIG. 5A, the heat exchange components 25 are arranged in
a regular lattice. In this case, the gaps 201 having a fast flow
velocity are aligned in the direction parallel to the y direction
to form a region having a fast flow velocity continuing from the
feed to the ejection of the heat transport medium 20. That is, it
is found that the heat transport medium 20 flows selectively and
rapidly in the portion having a low channel resistance.
[0081] On the other hand, in FIG. 5B, the heat exchange components
25 are arranged in a staggered lattice. In this case, the region
having a fast flow velocity continuing from the feed to the
ejection of the heat transport medium 20 is not formed. The gaps
202 having a relatively slow flow velocity predominate.
[0082] Furthermore, as shown in FIG. 5B, turbulence is observed at
many sites 203.
[0083] More specifically, in the case where the heat exchange
components 25 are arranged in a regular lattice, the heat transport
medium 20 flows selectively and rapidly in the portion having a low
channel resistance. Furthermore, many portions 27 constitute a dead
volume (the volume of the heat transport medium 20 contributing
less to heat exchange). This decreases the heat exchange efficiency
between the heat exchange component 25 and the heat transport
medium 20.
[0084] In contrast, in the case where the heat exchange components
25 are arranged in a staggered lattice, the flow velocity can be
made generally slower than in the case where the heat exchange
components 25 are arranged in a regular lattice. Furthermore,
turbulence can be caused at many sites 203 between the heat
exchange components 25. This turbulence occurs in a large gap
between the adjacent heat exchange components 25. Thus, the
portions 27 constituting a dead volume can be reduced. This also
facilitates heat exchange between the heat exchange components 25.
As a result, the effective heat exchange efficiency can be
increased.
[0085] As shown in FIG. 5A, in the case where the heat exchange
components 25 are arranged in a regular lattice, the turbulence
only forms a small vortex slightly at the end portion of the heat
exchange components 25. It is found that this does not contribute
to heat exchange between the adjacent heat exchange components
25.
[0086] Next, the relationship between the arrangement configuration
of the heat exchange components and the amount of heat exchange is
illustrated.
[0087] FIGS. 6A and 6B are schematic views for illustrating the
arrangement configuration of the heat exchange components. Here,
FIG. 6A is a schematic view for illustrating an example (Practical
example 1) of the arrangement configuration of the heat exchange
components according to this embodiment. FIG. 6B is a schematic
view for illustrating an arrangement configuration of the heat
exchange components according to Comparative example 1.
[0088] As shown in FIG. 6A, in the arrangement configuration of the
heat exchange components according to Practical example 1, the heat
exchange components 22 were periodically arrayed in a staggered
lattice. The heat exchange components 22 were arranged parallel to
the y direction and parallel to each other. The dimension d1
between the heat exchange components 22 in the x direction, the
dimension d2 between the heat exchange components 22 in the y
direction, and the dimension a1 of the heat exchange component 22
were set so that d1=0.7.times.a1 and d2=0.5.times.a1. Then, the
adjacent columns were displaced by half phase in the x direction so
that the heat exchange components 22 were periodically arrayed in a
staggered lattice.
[0089] As shown in FIG. 6B, in the arrangement configuration of the
heat exchange components according to Comparative example 1, the
heat exchange components 22 were periodically arrayed in a regular
lattice. The heat exchange components 22 were arranged parallel to
the y direction and parallel to each other. The dimension d1
between the heat exchange components 22 in the x direction, the
dimension d2 between the heat exchange components 22 in the y
direction, and the dimension a1 of the heat exchange component 22
were set so that d1=0.7.times.a1 and d2=0.5.times.a1.
[0090] Then, it was assumed that the heat transport medium 20 was
fed to fill the space other than the heat exchange components 22
and caused to flow therein. In this assumption, the amount of heat
exchange between the heat exchange component 22 and the heat
transport medium 20 was determined by simulation.
[0091] In this case, it was assumed that the heat transport medium
20 was water, the ambient temperature was 25.degree. C., the
frequency of the magnetic refrigeration cycle was 1 Hz, and the
flow distance of the heat transport medium 20 was 10.times.a1.
Then, the amount of heat exchange between the heat exchange
component 22 and the heat transport medium 20 per unit time was
calculated.
[0092] The amount of heat exchange was calculated under the
assumption that the periodic structure illustrated in FIGS. 6A and
6B were infinitely repeated. In this case, in those illustrated in
FIGS. 6A and 6B, the volume of the heat exchange components 22 in
the same capacity is equal.
[0093] Furthermore, as Practical example 2, the dimensional
relation in Practical example 1 was changed to d1=0.8.times.a1 and
d2=0.2.times.a1.
[0094] As Comparative example 2, the dimensional relation in
Comparative example 1 was changed to d1=0.8.times.a1 and
d2=0.2.times.a1.
[0095] The other conditions in Practical example 2 and Comparative
example 2 were made the same as those in Practical example 1 and
Comparative example 1.
[0096] FIGS. 7A and 7B are graphs for illustrating the comparison
between the amount of heat exchange of the practical example and
the amount of heat exchange of the comparative example. Here, FIG.
7A is a graph for illustrating the comparison between the amount of
heat exchange of Practical example 1 and the amount of heat
exchange of Comparative example 1. FIG. 7B is a graph for
illustrating the comparison between the amount of heat exchange of
Practical example 2 and the amount of heat exchange of Comparative
example 2.
[0097] As seen from FIG. 7A, in Practical example 1, the amount of
heat exchange can be made larger than in Comparative example 1.
[0098] As seen from FIG. 7B, in Practical example 2, the amount of
heat exchange can be made larger by 20% or more than in Comparative
example 2.
[0099] Thus, even in the case of heat exchange components having an
equal volume in the same capacity and also placed with an equal
spacing between the heat exchange components, it was confirmed that
the amount of heat exchange between the heat exchange component and
water can be made larger for a periodic array in a staggered
lattice than for a periodic array in a regular lattice.
[0100] That is, a plurality of heat exchange components are
regularly arrayed in the container. Furthermore, the heat transport
medium 20 such as water is fed to fill the container. While causing
the heat transport medium 20 to flow therein, heat exchange is
performed between the heat exchange component and the heat
transport medium 20. In this case, the arrangement configuration of
the heat exchange components according to this embodiment can
increase the amount of heat exchange.
[0101] Next, methods for arranging the heat exchange components are
illustrated.
[0102] As illustrated in FIG. 1B, the heat exchange components can
be fixed at the end portion in the z direction.
[0103] In this case, a group of heat exchange components can be
formed outside the container 11 and placed inside the container 11.
This can improve the productivity.
[0104] FIGS. 8A to 8D are schematic views for illustrating a method
for arranging the heat exchange components.
[0105] As shown in FIG. 8A, a group of heat exchange components 22a
with one end portion in the z direction fixed, and a group of heat
exchange components 22b with the other end portion in the z
direction fixed, can be formed and alternately placed inside the
container 11. Here, FIGS. 8A to 8D show the case of forming the
groups of heat exchange components along the y direction.
[0106] For instance, groups of heat exchange components 22a, 22b as
illustrated in FIGS. 8B, 8C, and 8D can be formed and alternately
placed inside the container 11.
[0107] In this case, one end portions of the plurality of heat
exchange components 22a are connected to each other via a
plate-like member. One end portions of the plurality of heat
exchange components 22b are connected to each other via a
plate-like member.
[0108] FIGS. 9A to 9D are also schematic views for illustrating a
method for arranging the heat exchange components.
[0109] As shown in FIG. 9A, a group of heat exchange components 22a
with one end portion in the z direction fixed, and a group of heat
exchange components 22b with the other end portion in the z
direction fixed, can be formed and alternately placed inside the
container 11. Here, FIGS. 9A to 9D show the case of forming the
groups of heat exchange components along the x direction.
[0110] For instance, groups of heat exchange components 22a, 22b as
illustrated in FIGS. 9B, 9C, and 9D can be formed and alternately
placed inside the container 11.
[0111] FIGS. 10A and 10B are also schematic views for illustrating
a method for arranging the heat exchange components.
[0112] As shown in FIG. 10A, a group of heat exchange components
22a, 22b with one end portion in the z direction fixed can be
formed and placed inside the container 11.
[0113] For instance, a group of heat exchange components 22a, 22b
as illustrated in FIG. 10B can be formed and placed inside the
container 11.
[0114] The heat exchange components according to the above
embodiment are integrated in the z direction. However, the heat
exchange components can also be divided in the z direction.
[0115] The foregoing relates to the case of arranging heat exchange
components formed from the same magnetocaloric effect material.
However, the embodiment is not limited thereto.
[0116] The characteristics of the magnetocaloric effect material
are maximized near the Curie temperature Tc. In the temperature
region too distant from the Curie temperature Tc, the
characteristics may be significantly degraded, or the
magnetocaloric effect may fail to be developed.
[0117] As described above, the magnetic refrigeration system based
on the AMR technique is operated with a temperature gradient formed
between both ends (high temperature end and low temperature end) of
the heat exchanger. Thus, arranging heat exchange components formed
from the same magnetocaloric effect material may partly produce a
portion with degraded characteristics.
[0118] FIGS. 11A and 11B are schematic sectional views for
illustrating cases of arranging heat exchange components formed
from different magnetocaloric effect materials.
[0119] FIG. 11A shows the case of arranging groups of heat exchange
components formed from different magnetocaloric effect materials
along the y direction. More specifically, the heat exchange
components are formed from a different magnetocaloric effect
material for each region provided along the flowing direction of
the heat transport medium 20.
[0120] For instance, FIG. 11A shows the case of selecting
magnetocaloric effect materials having Curie temperatures Tc suited
to the temperature gradient, and providing groups of heat exchange
components formed from the selected magnetocaloric effect
materials.
[0121] For instance, in FIG. 11A, the inflow side of the heat
transport medium 20 is the low temperature end, and the outflow
side is the high temperature end. Then, a magnetocaloric effect
material having the Curie temperature Tca suited to the temperature
of the low temperature end is selected, and heat exchange
components 32a are formed from the selected magnetocaloric effect
material. A magnetocaloric effect material having the Curie
temperature Tcc suited to the temperature of the high temperature
end is selected, and heat exchange components 32c are formed from
the selected magnetocaloric effect material. For the region between
the low temperature end and the high temperature end, a
magnetocaloric effect material having the Curie temperature Tcb
suited to the temperature of that region is selected, and heat
exchange components 32b are formed from the selected magnetocaloric
effect material.
[0122] This can suppress partial characteristics degradation, and
thus can improve the heat exchange efficiency.
[0123] The number of regions provided with the groups of heat
exchange components is not limited to those illustrated, but can be
appropriately modified.
[0124] FIG. 11B shows the case of arranging heat exchange
components formed from magnetocaloric effect materials having
different Curie temperatures Tc in a mixed manner.
[0125] This can expand the operating temperature region of the
magnetic refrigeration system.
[0126] Here, for instance, also in the case of forming groups of
heat exchange components as illustrated in FIGS. 10A to 11B, it is
preferable to provide a magnetic field generating section so that
the application direction of the magnetic field is directed in the
z direction (parallel to the longest side of each heat exchange
component).
Second Embodiment
[0127] FIG. 12 is a schematic configuration view for illustrating a
magnetic refrigeration system according to a second embodiment.
[0128] FIG. 13 is a schematic line diagram of the magnetic
refrigeration system according to the second embodiment.
[0129] Here, FIGS. 12 and 13 illustrate, as an example, the case
where a heat transport medium 20 subjected to heat absorption in a
heat exchange section 1 is sent to a low temperature side heat
exchange section 125 and caused to perform heat exchange with a
heat exchange target, not shown, in the low temperature side heat
exchange section 125.
[0130] As shown in FIGS. 12 and 13, the magnetic refrigeration
system 100 includes heat exchangers 1, a feed piping 103, an
ejection piping 104, a magnetic field generating section 105a, a
magnetic field generating section 105b, a rotary board 106a, a
rotary board 106b, a low temperature side heat exchange section
125, and a heat dissipating section 126.
[0131] As shown in FIG. 12, a pair of rotary boards 106a, 106b are
provided so as to sandwich two heat exchange sections 1
therebetween. The rotary boards 106a, 106b are supported by a
common shaft 107. This shaft 107 is located at the center of the
two heat exchange sections 1. The magnetic field generating
sections 105a, 105b are held inside the neighborhood of the
periphery of the rotary boards 106a, 106b, respectively. The
magnetic field generating sections 105a, 105b are opposed to each
other, and coupled via a yoke (not shown) to each other. Thus, a
magnetic field space is formed in the gap between the magnetic
field generating sections 105a, 105b paired with each other.
[0132] The magnetic field generating section 105a, 105b can be e.g.
a permanent magnet. The permanent magnet can be e.g. a NdFeB
(neodymium-iron-boron) magnet, SmCo (samarium-cobalt) magnet, or
ferrite magnet. Each time the rotary boards 106a, 106b are rotated
90 degrees, the magnetic field generating section 105a, 105b repeat
approach and separation with respect to the heat exchange sections
1. In the state in which a pair of magnetic field generating
sections 105a, 105b come closest to the respective heat exchange
sections 1, the heat exchange section 1 is located in the magnetic
field space formed between the magnetic field generating sections
105a, 105b. Thus, a magnetic field is applied to the heat exchange
component provided inside the container 11. When the state of the
magnetic field being applied to the heat exchange component is
switched to the state of the magnetic field being removed, the
entropy of the electron magnetic spin system increases. This causes
migration of entropy between the lattice system and the electron
magnetic spin system. Accordingly, the temperature of the heat
exchange component decreases. This is transferred to the heat
transport medium 20 and decreases the temperature of the heat
transport medium 20. The heat transport medium 20 with the
temperature thus decreased is ejected from the heat exchange
section 1 through the ejection piping 104 and supplied as a coolant
to the low temperature side heat exchange section 125.
[0133] The heat transport medium 20 can be e.g. a gas such as air
and nitrogen gas, water, an oil-based medium such as mineral oil
and silicone, or a solvent-based medium such as alcohols (e.g.,
ethylene glycol).
[0134] In this case, water has the highest specific heat and is
inexpensive. However, water may freeze in the temperature region of
0.degree. C. or less. Thus, it is possible to use e.g. an oil-based
medium, a solvent-based medium, a mixed liquid of water and an
oil-based medium, or a mixed liquid of water and a solvent-based
medium. Depending on the operating temperature region of the
magnetic refrigeration system 100, the liquid can be appropriately
modified in kind and mixing ratio.
[0135] In the case illustrated in FIG. 12, the magnetic field
generating sections 105a, 105b, the rotary boards 106a, 106b, the
shaft 107 and the like constitute a magnetic field changing section
for changing the magnetic field to the heat exchanger 1.
[0136] In the case illustrated in FIG. 12, mechanical variation is
applied to the magnetic field generating section 105a, 105b side.
However, mechanical variation may be applied to the heat exchanger
1 side.
[0137] In the foregoing, as the magnetic field generating section
105a, 105b, a permanent magnet is illustrated. However, for
instance, an electromagnet can also be used as the magnetic field
generating section 105a, 105b. In the case of using an
electromagnet as the magnetic field generating section 105a, 105b,
means for applying mechanical variation can be connected to the
magnetic field generating section 105a, 105b. However,
alternatively, it is also possible to provide e.g. a switch for
switching between energization and deenergization of the
electromagnet.
[0138] On the upstream side of the feed piping 103, a tank 121
storing the heat transport medium 20 is provided. In the midstream
of the feed piping 103, a transport section 122 is provided. The
transport section 122 feeds the heat exchange section 1 with the
heat transport medium 20. The ejection piping 104 is divided into
two lines after exiting the heat exchange section 1 to constitute
two circulation lines. In the midstream of one circulation line
(cooling line 123), a valve 131, the low temperature side heat
exchange section 125, and a valve 133 are provided. The tail end of
the cooling line 123 is connected to the tank 121. In the midstream
of the other circulation line (precooling line 124), a valve 132,
the heat dissipating section 126, and a valve 134 are provided. The
tail end of the precooling line 124 is connected to the tank
121.
[0139] Furthermore, a control section, not shown, for controlling
e.g. the operation of the rotary boards 106a, 106b and the
opening/closing operation of the valves 131-134 is provided.
[0140] Next, the operation of the magnetic refrigeration system 100
is illustrated.
[0141] The magnetic refrigeration system 100 is operated by
alternately repeating a precooling step and a cooling step.
[0142] First, in the precooling step, with the valve 131 and the
valve 133 closed, the valves 132 and 134 are opened to circulate
the heat transport medium 20 in the precooling line 124. In this
state, the magnetic field generating sections 105a, 105b are made
close to the heat exchange sections 1. When a magnetic field is
applied to the heat exchange components provided inside the
container 11, the temperature of the heat exchange components
increases. This is transferred to the heat transport medium 20 and
increases the temperature of the heat transport medium 20. The heat
transport medium 20 thus warmed is ejected from the heat exchange
section 1 through the ejection piping 104 and fed through the valve
132 into the heat dissipating section 126, where it is cooled. The
cooled heat transport medium 20 returns into the tank 121 through
the valve 134.
[0143] When the temperature of the heat exchange components
provided inside the container 11 has decreased close to the
temperature of the heat transport medium 20 supplied through the
feed piping 103 to the heat exchange sections 1, the valves 132,
134 are closed. Thus, the precooling step is terminated and passed
to the cooling step.
[0144] In the cooling step, first, the magnetic field generating
sections 105a, 105b are distanced from the heat exchange sections
1. Next, the valve 131 and the valve 133 are opened to circulate
the heat transport medium 20 in the cooling line 123. When the
magnetic field is removed from the heat exchange components, the
temperature of the heat exchange components decreases. This is
transferred to the heat transport medium 20 and decreases the
temperature of the heat transport medium 20. The heat transport
medium 20 thus cooled is ejected from the heat exchange section 1
through the ejection piping 104 and fed through the valve 131 into
the low temperature side heat exchange section 125. In the low
temperature side heat exchange section 125, heat exchange is
performed between the heat transport medium 20 subjected to heat
absorption in the heat exchanger 1 and a heat exchange target, not
shown. The low temperature side heat exchange section 125 can be
e.g. a section for cooling air by performing heat exchange between
the heat transport medium 20 at low temperature and air.
[0145] The heat transport medium 20 is subjected to heat exchange
in the low temperature side heat exchange section 125, and its
temperature is increased. Then, the heat transport medium 20
returns into the tank 121 through the valve 133.
[0146] When the temperature of the heat exchange components
provided inside the container 11 has increased close to the
temperature of the heat transport medium 20 supplied through the
feed piping 103 to the heat exchange sections 1, the valves 131,
133 are closed. Thus, the cooling step is terminated and passed
again to the precooling step.
[0147] In this case, the control section, not shown, controls e.g.
the operation of the rotary boards 106a, 106b and the
opening/closing operation of the valves 131-134, and alternately
repeats the precooling step and the cooling step described
above.
[0148] In the foregoing, as an example, the magnetic refrigeration
system using the heat absorption effect in the heat exchange
sections 1 is illustrated. However, the embodiment is not limited
thereto. For instance, the magnetic refrigeration system can also
be configured to use the heat generation effect in the heat
exchange sections 1. Alternatively, the magnetic refrigeration
system can also be configured to use the heat absorption effect and
the heat generation effect in the heat exchange sections 1. For
instance, the heat dissipating section 126 provided in the magnetic
refrigeration system 100 can be used as a high temperature side
heat exchange section to perform heat exchange between the heat
transport medium 20 at high temperature and air. Thus, in this
example, air can be heated.
[0149] The heat transport medium 20 transports cool heat or warm
heat to the low temperature side heat exchange section or the high
temperature side heat exchange section. The heat transport from the
low temperature side heat exchange section or the high temperature
side heat exchange section to the cooled section or the heat
dissipating section is preferably performed by a gas such as air,
helium, and carbon dioxide.
[0150] The embodiments described above can realize a heat exchanger
and a magnetic refrigeration system capable of improving the heat
transport efficiency.
[0151] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions. Moreover, above-mentioned embodiments can be combined
mutually and can be carried out.
[0152] For instance, the shape, dimension, material, layout, number
and the like of various components in the heat exchanger 1, the
magnetic refrigeration system 100 and the like are not limited to
those illustrated above, but can be appropriately modified.
* * * * *