U.S. patent application number 15/907485 was filed with the patent office on 2019-02-14 for wire, heat exchanger, and magnetic heat pump device.
This patent application is currently assigned to Fujikura Ltd.. The applicant listed for this patent is Fujikura Ltd.. Invention is credited to Kohki Ishikawa, Takeshi Kizaki, Masahiro Kondo, Ryujiro Nomura, Katsuhiko Takeuchi.
Application Number | 20190049158 15/907485 |
Document ID | / |
Family ID | 61557086 |
Filed Date | 2019-02-14 |
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United States Patent
Application |
20190049158 |
Kind Code |
A1 |
Nomura; Ryujiro ; et
al. |
February 14, 2019 |
WIRE, HEAT EXCHANGER, AND MAGNETIC HEAT PUMP DEVICE
Abstract
[Object] To provide a wire capable of obtaining a wide
temperature span. [Solving Means] An outer surface 121 of a wire
12A formed of a magnetocaloric material having a magnetocaloric
effect partially has at least one of a concave portion 122 and a
convex portion 123, the concave portion 122 is recessed in a radial
direction of the wire 12A, and the convex portion 123 protrudes in
the radial direction in a longitudinal direction of the wire
12A.
Inventors: |
Nomura; Ryujiro;
(Sakura-shi, JP) ; Kizaki; Takeshi; (Sakura-shi,
JP) ; Takeuchi; Katsuhiko; (Sakura-shi, JP) ;
Kondo; Masahiro; (Sakura-shi, JP) ; Ishikawa;
Kohki; (Sakura-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fujikura Ltd. |
Tokyo |
|
JP |
|
|
Assignee: |
Fujikura Ltd.
Tokyo
JP
|
Family ID: |
61557086 |
Appl. No.: |
15/907485 |
Filed: |
February 28, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 2321/0021 20130101;
F25B 21/00 20130101; H01F 1/012 20130101; F25B 2321/002
20130101 |
International
Class: |
F25B 21/00 20060101
F25B021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 10, 2017 |
JP |
2017-155813 |
Claims
1. A wire which is formed of a magnetocaloric material having a
magnetocaloric effect, wherein an outer surface of the wire
partially has at least one of a concave portion and a convex
portion in a longitudinal direction of the wire, the concave
portion is recessed in a radial direction of the wire, and the
convex portion protrudes in the radial direction.
2. The wire according to claim 1, wherein the wire has a
non-circular cross-sectional shape, and a cross-sectional shape at
one position in the longitudinal direction and a cross-sectional
shape at the other position in the longitudinal direction have a
rotational symmetry relationship.
3. The wire according to claim 1, wherein the wire has a
non-circular cross-sectional shape, and the wire is twisted in a
circumferential direction of the wire.
4. The wire according to claim 2, wherein the cross-sectional shape
of the wire includes an oval shape, a semi-circular shape, or an
n-polygonal shape (n is a natural number from 3 to 8).
5. The wire according to claim 1, wherein a cross-sectional shape
at one position in the longitudinal direction and a cross-sectional
shape at the other position in the longitudinal direction are
different from each other.
6. The wire according to claim 1, wherein a cross-sectional area at
one position in the longitudinal direction and a cross-sectional
area at the other position in the longitudinal direction are
different from each other.
7. The wire according to claim 5, wherein the wire has a columnar
shape having at least one of the concave portion and the convex
portion.
8. The wire according to claim 6, wherein the wire has a columnar
shape having at least one of the concave portion and the convex
portion.
9. The wire according to claim 5, wherein at least one of the
concave portion and the convex portion includes at least one of a
wall and a groove formed on an outer surface of the wire, and an
extending direction of at least one of the groove and the wall
includes at least the circumferential direction of the wire as an
element.
10. The wire according to claim 6, wherein at least one of the
concave portion and the convex portion includes at least one of a
wall and a groove formed on an outer surface of the wire, and an
extending direction of at least one of the groove and the wall
includes at least the circumferential direction of the wire as an
element.
11. A heat exchanger comprising: an assembly which is obtained by
bundling the wires according to claim 1; and a casing which
accommodates the assembly.
12. A magnetic heat pump device comprising: at least one heat
exchanger according to claim 11; a magnetic field changer
configured to apply a magnetic field to the magnetocaloric material
and change the magnitude of the magnetic field; first and second
external heat exchangers respectively connected to the heat
exchanger through a pipe; and a fluid supplier configured to supply
a fluid from the heat exchanger to the first or second external
heat exchanger in synchronization with the operation of the
magnetic field changer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a wire used in a magnetic
heat pump device using a magnetocaloric effect, and a heat
exchanger and a magnetic heat pump device including the wire.
[0002] The present application claims priority from Japanese Patent
Application No. 2017-155813 filed on Aug. 10, 2017. The contents
described and/or illustrated in the documents relevant to the
Japanese Patent Application No. 2017-155813 will be incorporated
herein by reference as a part of the description and/or drawings of
the present application.
BACKGROUND ART
[0003] In order to suppress an increase in pressure loss, a heat
exchanger is known in which a plurality of linear magnetic bodies
are inserted in a tubular casing while being overlapped in a
direction intersecting the longitudinal direction of the magnetic
body (for example, see Patent Document 1).
CITATION LIST
Patent Document
[0004] Patent Document 1: JP 2013-64588 A
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0005] When a magnetic heat pump device reaches a steady state, a
temperature gradient is generated in the heat exchanger so that a
uniform temperature span is formed between a high temperature end
and a low temperature end of the heat exchanger. It is desirable
that the temperature span become wider and thus the applicability
of the magnetic heat pump increases. However, there is a problem in
which the above-described linear magnetic body has a narrow
temperature span compared to a granular magnetic body.
[0006] An object of the invention is to provide a wire capable of
obtaining a wide temperature span and a heat exchanger and a
magnetic heat pump device including the wire.
Means for Solving Problem
[0007] A wire according to the invention is a wire which is formed
of a magnetocaloric material having a magnetocaloric effect, in
which an outer surface of the wire partially has at least one of a
concave portion and a convex portion in a longitudinal direction of
the wire, the concave potion is recessed in a radial direction of
the wire, and the convex portion protrudes in the radial
direction.
[0008] In the above-described invention, the wire may have a
non-circular cross-sectional shape, and a cross-sectional shape at
one position in the longitudinal direction and a cross-sectional
shape at the other position in the longitudinal direction may have
a rotational symmetry relationship.
[0009] In the above-described invention, the wire may have a
non-circular cross-sectional shape, and the wire may be twisted in
a circumferential direction of the wire.
[0010] In the above-described invention, the cross-sectional shape
of the wire may include an oval shape, a semi-circular shape, or an
n-polygonal shape (n is a natural number from 3 to 8).
[0011] In the above-described invention, a cross-sectional shape at
one position in the longitudinal direction and a cross-sectional
shape at the other position in the longitudinal direction may be
different from each other.
[0012] In the above-described invention, a cross-sectional area at
one position in the longitudinal direction and a cross-sectional
area at the other position in the longitudinal direction may be
different from each other.
[0013] In the above-described invention, the wire may have a
columnar shape having at least one of the concave portion and the
convex portion.
[0014] In the above-described invention, at least one of the
concave portion and the convex portion may include at least one of
a wall and a groove formed on an outer surface of the wire, and an
extending direction of at least one of the groove and the wall may
include at least the circumferential direction of the wire as an
element.
[0015] A heat exchanger according to the invention is a heat
exchanger including: an assembly which is obtained by bundling a
plurality of the above-described wires; and a casing which
accommodates the assembly.
[0016] In the above-described invention, the casing may include a
first opening located at one end portion and a second opening
located at the other end portion, and a direction from the first
opening to the second opening may substantially match the extending
direction of the assembly.
[0017] A magnetic heat pump device according to the invention is a
magnetic heat pump device comprising: at least one of the
above-described heat exchangers; a magnetic field changer
configured to apply a magnetic field to the magnetocaloric material
and change the magnitude of the magnetic field; first and second
external heat exchangers respectively connected to the heat
exchanger through a pipe; and a fluid supplier configured to supply
a fluid from the heat exchanger to the first or second external
heat exchanger in synchronization with the operation of the
magnetic field changer.
Effect of the Invention
[0018] In the invention, the outer surface of the wire partially
has at least one of the concave portion and the convex portion in
the longitudinal direction of the wire. Accordingly, since a flow
of a fluid flowing on the surface of the wire becomes turbulent and
a heat transfer rate between the wire and the fluid can be
enhanced, it is possible to obtain a wide temperature span.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a diagram illustrating an overall configuration of
a magnetic heat pump device in a first embodiment of the invention
and is a diagram illustrating a state where a piston is located at
a first position;
[0020] FIG. 2 is a diagram illustrating an overall configuration of
the magnetic heat pump device in the first embodiment of the
invention and is a diagram illustrating a state where the piston is
located at a second position;
[0021] FIG. 3 is an exploded perspective view illustrating a
configuration of an MCM heat exchanger in the first embodiment of
the invention;
[0022] FIG. 4 is a cross-sectional view taken along the extending
direction of the MCM heat exchanger in the first embodiment of the
invention and is a cross-sectional view taken alone a line IV-IV of
FIG. 3;
[0023] FIG. 5 is a cross-sectional view taken along a line V-V of
FIG. 4;
[0024] FIG. 6 is a perspective view illustrating a wire in the
first embodiment of the invention;
[0025] FIG. 7(A) is an end view when the wire is cut along a line
VIIA-VIIA of FIG. 6 and FIG. 7(B) is an end view when the wire is
cut along a line VIIB-VIIB of FIG. 6;
[0026] FIG. 8 is an end view when the wire is cut along a line
VIII-VIII of FIG. 6;
[0027] FIGS. 9(A) to 9(L) are end views illustrating a modified
example of the wire in the first embodiment of the invention;
[0028] FIG. 10 is a side view illustrating a wire in a second
embodiment of the invention;
[0029] FIG. 11(A) is a cross-sectional view when the wire is cut
along a line XIA-XIA of FIG. 10 and FIG. 11(B) is a cross-sectional
view when the wire is cut alone a line XIB-XIB of FIG. 10;
[0030] FIG. 12 is a cross-sectional view when the wire is cut along
a line XII-XII of FIG. 10; and
[0031] FIGS. 13(A) to 13(E) are side views illustrating a modified
example of the wire in the second embodiment of the invention.
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0032] Hereinafter, a first embodiment of the invention will be
described with reference to the drawings.
First Embodiment
[0033] FIGS. 1 and 2 are diagrams illustrating an overall
configuration of a magnetic heat pump device in the first
embodiment of the invention, FIGS. 3 to 5 are diagrams illustrating
an MCM heat exchanger in the first embodiment of the invention, and
FIGS. 6 to 8 are diagrams illustrating a wire in the first
embodiment of the invention. FIGS. 9(A) to 9(L) are cross-sectional
views illustrating a modified example of the wire in the first
embodiment of the invention.
[0034] A magnetic heat pump device 1 of this embodiment is a heat
pump device using a magnetocaloric effect and includes, as
illustrated in FIGS. 1 and 2, first and second MCM heat exchangers
10 and 20, a piston 30, a permanent magnet 40, a low temperature
side heat exchanger 50, a high temperature side heat exchanger 60,
a rotary pump 70, pipes 81 to 84, and a switching valve 90.
[0035] The first and second MCM heat exchangers 10 and 20 of this
embodiment correspond to an example of the heat exchanger of the
invention, the piston 30 and the permanent magnet 40 of this
embodiment correspond to an example of a magnetic changer of the
invention, the low temperature side heat exchanger 50 and the high
temperature side heat exchanger 60 correspond to an example of
first and second external heat exchangers of the invention, the
pipes 81 to 84 of this embodiment correspond to an example of a
pipe of the invention, and the pump 70 and the switching valve 90
of this embodiment correspond to an example of a fluid supplier of
the invention.
[0036] The first MCM heat exchanger 10 includes, as illustrated in
FIGS. 3 to 5, an assembly 11 which includes a plurality of wires
12A, a tubular casing (container) 13 which accommodates the
assembly 11, and terminal members 17 and 18 which are connected to
both ends of the casing 13. Since the first MCM heat exchanger 10
and the second MCM heat exchanger 20 have the same structure, only
the configuration of the first MCM heat exchanger 10 will be
described below and the description of the configuration of the
second MCM heat exchanger 20 will be omitted.
[0037] The wire 12A of this embodiment corresponds to an example of
the wire of the invention, the assembly 11 of this embodiment
corresponds to an example of the assembly of the invention, and the
casing 13 of this embodiment corresponds to an example of the
casing of the invention.
[0038] The wire 12A is composed of a magnetocaloric material (MCM)
having a magnetocaloric effect. When a magnetic field is applied to
the wire 12A formed of the MCM, magnetic entropy decreases as
electron spins are aligned and the wire 12A generates heat so that
a temperature rises. On the other hand, when the magnetic field is
removed from the wire 12A, the magnetic entropy increases as the
electron spins become cluttered and the wire 12A absorbs heat so
that a temperature falls.
[0039] The MCM forming the wire 12A is not particularly limited as
long as it is a magnetic body. However, a magnetic body having a
Curie temperature (Curie point) in a normal temperature range of
about 10.degree. C. to 30.degree. C. and exerts a high
magnetocaloric effect in a normal temperature range is desirable.
Detailed examples of such MCMs include gadolinium (Gd), gadolinium
alloy, lanthanum-iron-silicon (La--Fe--Si) based compounds, and the
like.
[0040] As illustrated in FIGS. 6 to 7(B), the wire 12A has a square
cross-sectional shape when the wire 12A is cut along a direction
substantially orthogonal to the longitudinal direction of the wire
12A. Further, the wire 12A is twisted in the circumferential
direction of the wire 12A when rotating in the opposite directions
at both ends of the wire 12A using the center of the wire 12A as a
rotation axis. The "square cross-sectional shape" in this
embodiment also includes those having slight deformation by
twisting (for example, those having side edges curved slightly
inward by twisting). Further, a method of forming the wire 12A is
not limited to the method of twisting a linear wire. For example, a
straight wire may be pressed or rolled into a twisted shape using a
metal mold or the like or a wire may be extruded into a twisted
shape.
[0041] In this way, in this embodiment, since the wire 12A is
twisted, an outer surface 121 of the wire 12A partially includes a
concave portion 122 and a convex portion 123 in the longitudinal
direction of the wire 12A as illustrated in FIG. 8. That is, in
this embodiment, the wire 12A has a cross-sectional shape in which
the outer surface 121 is partially provided with the concave
portion 122 and the convex portion 123 when the wire is cut along
the longitudinal direction of the wire 12A. The convex portion 123
is formed by the ridge of the wire 12A and protrudes in the radial
direction of the wire 12A. On the contrary, the concave portion 122
is formed by surfaces between the ridges of the wire 12A and is
recessed in the radial direction of the wire 12A. In this
embodiment, since the concave portion 122 and the convex portion
123 are formed by twisting the wire 12A, the concave portion 122
and the convex portion 123 are periodically and alternately
arranged in the longitudinal direction of the wire 12A. FIG. 8 is a
cross-sectional view when the wire 12A is cut along the
longitudinal direction of the wire 12A.
[0042] Further, in this embodiment, since the wire 12A having a
square cross-sectional shape (that is, a non-circular
cross-sectional shape) is twisted, the cross-sectional shape at one
position (for example, a line VIIA-VIIA illustrated in FIG. 6) in
the longitudinal direction and the cross-sectional shape at the
other position (for example, a line VIIB-VIIB illustrated in FIG.
6) in the longitudinal direction have a rotational symmetry
relationship as illustrated in FIGS. 7(A) and 7(B). FIGS. 7(A) and
7(B) are end views when the wire 12A is cut along a direction
substantially orthogonal to the longitudinal direction of the wire
12A.
[0043] Although there is no particular limitation, it is desirable
that the wire 12A have a diameter in which a diameter of a
circumscribed circle circumscribing a rectangular cross-sectional
shape of the wire 12A is about 0.05 mm to 3 mm. Further, although
there is no particular limitation, it is desirable that a twist
pitch P of the wire 12A be about 10 to 50 times longer than the
diameter of the circumscribed circle of the wire 12A.
[0044] The cross-sectional shape of the wire is not particularly
limited to the above-described square shape as long as the shape is
non-circular (that is, a shape other than a perfect circle).
[0045] For example, as illustrated in FIG. 9(A), a wire 12Aa may
have an oval cross-sectional shape. In this case, since the wire
12Aa can be produced only by pressing a wire having a circular
cross-sectional shape and then twisting the wire, it is possible to
facilitate the production of the wire. The "oval cross-sectional
shape" in this embodiment includes those having slight deformation
by twisting.
[0046] Alternatively, as illustrated in FIG. 9(B), the wire 12Ab
may have a semi-circular cross-sectional shape. In this case, since
the wire 12Ab can be produced only by forming a wire by a quenching
roll method and then twisting the wire, it is possible to
facilitate the production of the wire 12Ab. The "semi-circular
cross-sectional shape" in this embodiment includes those having
slight deformation by twisting.
[0047] Alternatively, as illustrated in FIGS. 9(C) to 9(F), the
wire 12Ac to 12Af may have an n-polygonal cross-sectional shape.
Here, n is a natural number of 3 to 8. The cross-sectional shape of
the wire is not limited to a regular n-polygon shape. For example,
as illustrated in FIG. 9(G), the wire 12Ag may have a rectangular
cross-sectional shape. Alternatively, as illustrated in FIG. 9(H),
the wire 12Ah may have a trapezoidal cross-sectional shape.
Although not specifically illustrated in the drawings, the wire may
have a cross-sectional shape of a parallelogram or a rhombus. In
this embodiment, the "n-polygonal cross-sectional shape" includes
those having slight deformation by twisting (for example, those
having side edges curved slightly inward by twisting).
[0048] Alternatively, as illustrated in FIG. 9(I), the wire 12Ai
may have a cross-shaped cross-sectional shape or the wires 12Aj to
12Al may have a star-shaped cross-sectional shape as illustrated in
FIGS. 9(J) to 9(L). Since the cross-sectional shapes of the wires
12Ai to 12Al illustrated in FIGS. 9(I) to 9(L) have portions
recessed inward, it is possible to further improve a turbulence of
a fluid generated on the surface of the wire. The "star-shaped
cross-sectional shape" in this embodiment includes those having
slight deformation by twisting.
[0049] The assembly 11 is formed by bundling a plurality of the
wires 12A. The plurality of wires 12A are bundled (overlapped) in a
direction intersecting the longitudinal direction of the wire 12A.
In other words, the plurality of wires 12A are adjacent to each
other so that the side surfaces of the wires 12A contact each
other. At this time, since the wire 12A has a non-circular
cross-sectional shape and is twisted as described above, a passage
111 (see FIG. 5) is formed between the side surfaces of the wires
12A. The plurality of wires 12 constituting the assembly 11 may
have substantially the same wire diameter or may have different
wire diameters. Further, in order to facilitate understanding, the
assembly 11 is formed by the wires 12A which are fewer than the
actual wires in FIGS. 3 to 5, but in fact, the assembly 11 includes
several thousand to several tens of thousands of wires 12A.
[0050] The assembly 11 illustrated in FIGS. 3 to 5 is formed by
simply bundling the plurality of wires 12A, but the configuration
of the assembly is not particularly limited thereto. Although not
specifically illustrated, for example, the assembly may be formed
by twisting a plurality of wires together. Alternatively, an
individual stranded wire may be formed by twisting several wires
and the assembly may be formed by bundling the plurality of
stranded wires. That is, the "assembly formed by bundling the
plurality of wires" in this embodiment also includes "stranded
wires."
[0051] As a method of twisting the wires, for example, collective
twisting, concentric twisting, complex twisting, and the like can
be exemplified. The collective twisting is a twisting method in
which a plurality of wires are bundled together and twisted in the
same direction about the axis of the assembly. The concentric
twisting is a twisting method in which a plurality of wires are
concentrically twisted around a core wire. The complex twisting is
a twisting method in which child stranded wires each of which is
obtained by twisting a plurality of wires by concentric twisting or
collective twisting are further twisted by concentric twisting or
collective twisting.
[0052] The casing 13 which accommodates the assembly 11 includes,
as illustrated in FIGS. 3 to 5, an accommodation portion 14 and a
lid portion 15 and has a tubular shape with a rectangular
cross-section. The casing 13 is formed such that one end portion is
provided with a first opening 131 and the other end portion is
provided with a second opening 132.
[0053] The accommodation portion 14 includes a bottom portion 141
which constitutes a bottom plate of the casing 13 and a pair of
side portions 142 and 143 which constitutes both side walls of the
casing 13. An opening 144 is formed between upper ends of the pair
of side portions 142 and 143. As a result, the accommodation
portion 14 has a square-cornered U-shaped (substantially U-shaped)
cross-sectional shape in a cross-section in a direction
substantially orthogonal to the axial direction thereof.
[0054] The lid portion 15 is a rectangular plate-shaped member. As
illustrated in FIGS. 3 to 5, the lid portion 15 is fixed to upper
ends of the pair of side portions 142 and 143. The opening 144 of
the accommodation portion 14 is blocked by the lid portion 15 so
that the casing 13 is formed.
[0055] The assembly 11 is accommodated in the casing 13 so that the
longitudinal direction (the extension direction (the longitudinal
direction) of the assembly 11) of the wire 12A constituting the
assembly 11 substantially matches the axial direction (a direction
extending from the first opening 131 to the second opening 132) of
the casing 13. Further, the centers of the first and second
openings 131 and 132 are located to be substantially coaxial to the
center of the assembly 11. Then, the passage 111 is formed between
the wires 12A constituting the assembly 11 (see FIG. 5).
[0056] As illustrated in FIGS. 3 and 4, one end portion of the
casing 13 is inserted into the first terminal member 17 and the
first terminal member 17 is fixed to the casing 13. Further, the
other end portion of the casing 13 is inserted into the second
terminal member 18 and the second terminal member 18 is fixed to
the casing 13. As the first and second terminal members (connection
members) 17 and 18, for example, a heat shrinkable tube, a resin
molded article, a metal processed article, or the like can be
used.
[0057] The first terminal member 17 includes a first connection
port 171 which is smaller than the first opening 131 of the casing
13. As illustrated in FIG. 1, the first connection port 171
communicates with the low temperature side heat exchanger 50
through the first low temperature side pipe 81. The second terminal
member 18 also includes a second connection port 181 which is
smaller than the second opening 132. The second connection port 181
communicates with the high temperature side heat exchanger 60
through the first high temperature side pipe 83. The centers of the
first and second connection ports 171 and 181 are located to be
coaxial to the center of the assembly 11.
[0058] Similarly, an assembly 21 is also accommodated in the casing
23 of the second MCM heat exchanger 20 (see FIG. 2) and the
assembly 21 is formed by bundling a plurality of wires 22A. Then,
similarly to the first MCM heat exchanger 10, one end portion of
the casing 23 is inserted into the first terminal member and the
first terminal member is fixed to the casing 23. Further, the other
end portion of the casing 23 is inserted into the second terminal
member and the second terminal member is fixed to the casing 23.
The second MCM heat exchanger 20 communicates with the low
temperature side heat exchanger 50 through the second low
temperature side pipe 82 connected to a first connection port 271
of the first terminal member. Meanwhile, the second MCM heat
exchanger 20 communicates with the high temperature side heat
exchanger 60 through the second high temperature side pipe 84
connected to a second connection port 281 of the second terminal
member.
[0059] The wire 22A of the second MCM heat exchanger 20 has the
same configuration as the wire 12A of the first MCM heat exchanger
10. Further, the casing 23 of the second MCM heat exchanger 20 also
have the same configuration as the casing 13 of the first MCM heat
exchanger 10, and the terminal members of the second MCM heat
exchanger 20 also has the same configuration as the terminal
members 17 and 18 of the first MCM heat exchanger 10.
[0060] For example, in a case where an air conditioner using the
magnetic heat pump device 1 of this embodiment is operated in a
cooling mode, an indoor place is cooled by a heat exchange between
the low temperature side heat exchanger 50 and the inside air, and
heat is emitted to an outdoor place by a heat exchange between the
high temperature side heat exchanger 60 and the outside air.
[0061] On the contrary, in a case where the air conditioner is
operated in a warming mode, the indoor place is warmed by a heat
exchange between the high temperature side heat exchanger 60 and
the inside air, and heat is absorbed from the outdoor place by a
heat exchange between the low temperature side heat exchanger 50
and the outside air.
[0062] As described above, a circulation path including four heat
exchangers 10, 20, 50, and 60 is formed by two low temperature side
pipes 81 and 82 and two high temperature side pipes 83 and 84, and
a liquid medium is pressure-fed in the circulation path by the
rotary pump 70. As a detailed example of the liquid medium, for
example, a liquid such as water, an antifreeze solution, an ethanol
solution, or a mixture thereof can be exemplified. The liquid
medium of this embodiment corresponds to an example of a fluid of
the invention.
[0063] Two MCM heat exchangers 10 and 20 are accommodated inside
the piston 30. The piston 30 can move in a reciprocating manner
between a pair of permanent magnets 40 by the actuator 35.
Specifically, the piston 30 can move in a reciprocating manner
between a "first position" illustrated in FIG. 1 and a "second
position" illustrated in FIG. 2. As an example of the actuator 35,
for example, an air cylinder or the like can be exemplified.
[0064] Here, the "first position" is a position of the piston 30
when the first MCM heat exchanger 10 is not interposed between the
permanent magnets 40 and the second MCM heat exchanger 20 is
interposed between the permanent magnets 40. On the contrary, the
"second position" is a position of the piston 30 when the first MCM
heat exchanger 10 is interposed between the permanent magnets 40
and the second MCM heat exchanger 20 is not interposed between the
permanent magnets 40.
[0065] Instead of the first and second MCM heat exchangers 10 and
20, the permanent magnet 40 may be moved in a reciprocating manner
by the actuator 35. Alternatively, an electromagnet having a coil
may be used instead of the permanent magnet 40. In this case, a
mechanism of moving the MCM heat exchangers 10 and 20 or the magnet
is not necessary. Further, when the electromagnet having the coil
is used, the magnitude of the magnetic field applied to the wires
12A and 22A may be changed instead of applying/removing of the
magnetic field with respect to the wires 12A and 22A of the MCM
heat exchangers 10 and 20.
[0066] The switching valve 90 is provided at the first high
temperature side pipe 83 and the second high temperature side pipe
84. In synchronization with the operation of the piston 30, the
switching valve 90 can switch the liquid medium supply destination
of the rotary pump 70 to the first MCM heat exchanger 10 or the
second MCM heat exchanger 20 and switch the connection destination
of the high temperature side heat exchanger 60 to the second MCM
heat exchanger 20 or the first MCM heat exchanger 10.
[0067] Next, an operation of the magnetic heat pump device 1 of
this embodiment will be described with reference to FIGS. 1 and
2.
[0068] First, when the piston 30 is moved to the "first position"
illustrated in FIG. 1, the wire 12A of the first MCM heat exchanger
10 is demagnetized so that a temperature falls and the wire 22 of
the second MCM heat exchanger 20 is magnetized so that a
temperature rises.
[0069] At the same time, a first path (the rotary pump 70 the first
high temperature side pipe 83 the first MCM heat exchanger 10 the
first low temperature side pipe 81 the low temperature side heat
exchanger 50 the second low temperature side pipe 82 the second MCM
heat exchanger 20 the second high temperature side pipe 84 the high
temperature side heat exchanger the rotary pump 70) is formed by
the switching valve 90.
[0070] For this reason, the liquid medium is cooled by the wire 12A
of the first MCM heat exchanger 10 of which a temperature decreases
due to a demagnetization and the liquid medium is supplied to the
low temperature side heat exchanger 50 so that the low temperature
side heat exchanger 50 is cooled. At this time, since the liquid
medium passes through the passage 111 formed between the wires 12A
inside the first MCM heat exchanger 10 so as to contact the wires
12A, the liquid medium is cooled by the wires 12A.
[0071] Meanwhile, the liquid medium is heated by the wire 22A of
the second MCM heat exchanger 20 of which a temperature increases
due to a magnetization and the liquid medium is supplied to the
high temperature side heat exchanger 60 so that the high
temperature side heat exchanger 60 is heated. At this time, since
the liquid medium passes through the passage formed between the
wires 22A inside the second MCM heat exchanger 20 so as to contact
the wires 22A, the liquid medium is heated by the wires 22A.
[0072] Next, when the piston 30 is moved to the "second position"
illustrated in FIG. 2, the wire 12A of the first MCM heat exchanger
10 is magnetized so that a temperature rises and the wire 22A of
the second MCM heat exchanger 20 is demagnetized so that a
temperature falls.
[0073] At the same time, a second path (the rotary pump 70 the
second high temperature side pipe 84 the second MCM heat exchanger
20 the second low temperature side pipe 82 the low temperature side
heat exchanger the first low temperature side pipe 81 the first MCM
heat exchanger 10 the first high temperature side pipe 83 the high
temperature side heat exchanger the rotary pump 70) is formed by
the switching valve 90.
[0074] For this reason, the liquid medium is cooled by the wire 22A
of the second MCM heat exchanger 20 of which a temperature
decreases due to a demagnetization and the liquid medium is
supplied to the low temperature side heat exchanger 50 so that the
low temperature side heat exchanger 50 is cooled. At this time,
since the liquid medium passes through the passage formed between
the wires 22A inside the second MCM heat exchanger 20 so as to
contact the wires 22A, the liquid medium is cooled by the wire
22A.
[0075] Meanwhile, the liquid medium is heated by the wire 12A of
the first MCM heat exchanger 10 of which a temperature increases
due to a magnetization and the liquid medium is supplied to the
high temperature side heat exchanger 60 so that the high
temperature side heat exchanger 60 is heated. At this time, since
the liquid medium passes through the first passage 111 formed
between the wires 12A inside the first MCM heat exchanger 10 so as
to contact the wires 12A, the liquid medium is heated by the wires
12A.
[0076] When the above-described cycle is repeated, the cold and hot
temperature generated by the magnetocaloric effect is accumulated
in the assemblies 11 and 21, the side connected to the high
temperature side pipe has a high temperature, and the side
connected to the low temperature side pipe has a low temperature.
Then, when a temperature gradient is formed inside the first and
second MCM heat exchangers 10 and 20 and the first and second MCM
heat exchangers 10 and 20 reaches a steady state, a uniform
temperature span .DELTA.T is generated between the high temperature
end and the low temperature end. The temperature span .DELTA.T is
expressed by the following equation (1). In the following equation
(1), T.sub.h indicates the temperature at the high temperature end
in the steady state and T.sub.1 indicates the temperature at the
low temperature end in the steady state.
[0077] [Math. 1]
.DELTA.T=T.sub.h-T.sub.1 (1)
[0078] Here, .DELTA.q which indicates the heat quantity per unit
time from the unit surface area of the magnetocaloric material to
the liquid medium is expressed by the following equation (2). In
the following equation (2), h indicates the heat exchange rate,
T.sub.s indicates the surface temperature of the magnetocaloric
material, and T.sub.f indicates the temperature of the liquid
medium.
[0079] [Math. 2]
.DELTA.q=h(T.sub.s-T.sub.f) (2)
[0080] Then, a state where the temperature span .DELTA.T becomes
uniform due to the repeated cycle (a state where the temperature
span .DELTA.T is saturated) is a state where the heat quantity
.DELTA.q of the above-described equation (2) is sufficiently small
and a change .DELTA.T.sub.f of the refrigerant temperature T.sub.f
for each cycle disappears. Thus, according to the above-described
equation (1), the magnitude of the temperature span .DELTA.T
depends on the magnitude of the heat transfer rate h.
[0081] In general, the heat exchange rate h in the above-described
equation (2) is determined by the shape of the magnetocaloric
material and the filling method. Regarding some shapes such as a
granular or linear shape, the heat exchange rate h is formulated by
the Nusselt number Nu. That is, when the Nusselt number Nu is
large, it can be considered that the heat transfer rate h is also
large. Then, when the liquid medium flows at the same speed, the
Nusselt number Nu.sub.1 of the granular material can be expressed
by the following equation (3) and the Nusselt number Nu.sub.2 of
the wire can be expressed by the following equation (4). In the
following equations (3) and (4), Re is Reynolds number and Pr is
Prandtl number.
[0082] [Math. 3]
Nu.sub.1=2+0.6Re.sup.0.5Pr.sup.0.33 (3)
[0083] [Math. 4]
Nu.sub.2=0.023Re.sup.0.8Pr.sup.0.33 (4)
[0084] According to the above-described equations (3) and (4),
since the Nusselt number Nu.sub.2 of the wire is smaller than the
Nusselt number Nu.sub.1 of the granular material, it is understood
that the heat transfer rate of the granular is lower than that of
the wire. That is, the temperature span AT of the wire not twisted
is narrower than that of the granular material. The Nusselt number
Nu.sub.2 illustrated in the above-described equation (4) is
calculated on a condition that the flow of the liquid refrigerant
flowing on the surface of the wire is a laminar flow and the heat
exchange between the wire surface and the liquid refrigerant is
performed by natural convection.
[0085] On the contrary, in this embodiment, the concave portion 122
and the convex portion 123 are partially provided in the outer
surface 121 of the wire 12A in the longitudinal direction of the
wire 12A. Accordingly, the liquid medium flowing on the surface of
the wire 12A collides with the concave portion 122 or the convex
portion 123 so that forced convection occurs and the flow of the
liquid medium becomes turbulent. For this reason, since the heat
transfer rate between the wire 12A and the liquid medium can be
improved, a wide temperature span can be obtained.
Second Embodiment
[0086] FIGS. 10 to 12 are views illustrating a wire in a second
embodiment of the invention and FIGS. 13(a) to 13(e) are side views
illustrating a modified example of the wire in the second
embodiment of the invention. In this embodiment, the configuration
of the wire is different from that of the first embodiment, but the
other configurations are the same as those of the first embodiment.
Hereinafter, only a difference between the second embodiment and
the first embodiment will be described. Further, the same reference
numerals will be given to the same components as those of the first
embodiment and a description thereof will be omitted.
[0087] A wire 12B of this embodiment has, as illustrated in FIGS.
10 to 11(B), a circular cross-sectional shape when the wire 12B is
cut along a direction substantially orthogonal to the longitudinal
direction of the wire 12B. Further, the wire 12B is provided with a
groove 124 which extends in the circumferential direction and the
groove 124 is formed on the entire circumference of the wire 12B.
That is, the wire 12B of this embodiment has a columnar shape
provided with a plurality of the annular grooves 124. As
illustrated in the same drawing, in this embodiment, the plurality
of grooves 124 are arranged at the substantially equal intervals in
the longitudinal direction of the wire 12B, but the invention is
not particularly limited thereto. The wire 12B of this embodiment
is formed by cutting, pressing, or rolling a wire.
[0088] In this way, in this embodiment, since the wire 12B is
provided with the groove 124, the outer surface 121 of the wire 12B
partially includes the concave portion 122 in the longitudinal
direction of the wire 12B as illustrated in FIG. 12. That is, in
this embodiment, the wire 12B has a cross-sectional shape in which
the outer surface 121 partially includes the concave portion 122
when the wire 12B is cut along the longitudinal direction of the
wire 12B. FIG. 12 is a cross-sectional view when the wire 12B is
cut along the longitudinal direction of the wire 12B.
[0089] Further, in this embodiment, since the wire 12B is provided
with the groove 124, the cross-sectional area at one position (for
example, a line XIA-XIA of FIG. 10) in the longitudinal direction
and the cross-sectional area at the other position (for example, a
line XIB-XIB of FIG. 10) in the longitudinal direction are
different from each other as illustrated in FIGS. 11(A) and 11(B).
Further, in this embodiment, since the wire 12B is provided with
the groove 124, the cross-sectional shape at one position (for
example, a line XIA-XIA of FIG. 10) in the longitudinal direction
and the cross-sectional shape at the other position (for example, a
line XIB-XIB of FIG. 10) in the longitudinal direction are
different from each other as illustrated in FIGS. 11(A) and 11(B).
FIGS. 11(A) and 11(B) are cross-sectional views when the wire 12B
is cut along a direction substantially orthogonal to the
longitudinal direction of the wire 12B.
[0090] In this way, in this embodiment, the concave portion 122 is
partially provided in the outer surface 121 of the wire 12B in the
longitudinal direction of the wire 12B similarly to the first
embodiment. Accordingly, the liquid medium flowing on the surface
of the wire 12B collides with the concave portion 122 so that
forced convection occurs and the flow of the liquid medium becomes
turbulent. For this reason, since the heat transfer rate between
the wire 12B and the liquid medium can be increased, a wide
temperature span can be obtained.
[0091] The shape of the wire is not particularly limited. For
example, as illustrated in FIG. 13(A), a wire 12Ba may have a
columnar shape provided with a spiral groove 124. The extending
direction of the spiral groove 124 includes the circumferential
direction of the wire 12Ba as one element. Alternatively, as
illustrated in FIG. 13(B), the wire 12Bb may have a columnar shape
provided with a plurality of grooves 124 partially formed in the
circumferential direction.
[0092] Alternatively, as illustrated in FIG. 13(C), a wire 12Bc may
have a columnar shape provided with a plurality of annular walls
125. Alternatively, as illustrated in FIG. 13(D), a wire 12Bd may
have a columnar shape provided with a spiral wall 125. The
extending direction of the spiral wall 125 includes the
circumferential direction of the wire 12Bd as one element.
Alternatively, as illustrated in FIG. 13(E), a wire 12Be may have a
columnar shape provided with a plurality of walls 125 partially
formed in the circumferential direction.
[0093] Embodiments heretofore explained are described to facilitate
understanding of the present invention and are not described to
limit the present invention. It is therefore intended that the
elements disclosed in the above embodiments include all design
changes and equivalents to fall within the technical scope of the
present invention.
[0094] The configuration of the above-described magnetic heat pump
device is an example, and the heat exchanger according to the
invention may be applied to another magnetic heat pump device of an
AMR (Active Magnetic Refrigeration) type.
[0095] For example, the magnetic heat pump device may include one
MCM heat exchanger, a magnetic field changer configured to supply a
magnetic field to the MCM and change the magnitude of the magnetic
field, first and second external heat exchangers respectively
connected to the MCM heat exchanger through a pipe, and a fluid
supplier configured to supply a fluid to the first or second
external heat exchanger from the MCM heat exchanger in
synchronization with the operation of the magnetic field changer.
Further, in the above-described embodiment, the liquid medium flow
direction is changed by using the rotary pump 70 and the switching
valve 90, but a reciprocating pump may be used instead of the
rotary pump 70 and the switching valve 90.
[0096] Further, in the above-described embodiment, an example in
which the magnetic heat pump device is applied to the air
conditioner for home or an automobile has been described, but the
invention is not particularly limited thereto. For example, when an
MCM having an appropriate Curie temperature according to the
application is selected, the magnetic heat pump device according to
the invention may be used for an application in an extremely low
temperature range such as a refrigerator or in a high temperature
range to some extent.
[0097] Further, in this embodiment, the first and second MCM heat
exchangers 10 and 20 have the same configurations, but the
invention is not particularly limited thereto. Here, the heat
exchangers may have different configurations. For example, the
first and second MCM heat exchangers 10 and 20 may use wires having
different wire diameters. Further, the twisting pitches of the
wires may be different from each other.
[0098] Further, in this embodiment, the MCM heat exchanger includes
a single assembly, but the invention is not particularly limited
thereto. For example, a plurality of assemblies may be arranged in
series along the extending direction of the MCM heat exchanger. In
this case, the plurality of assemblies may have the same
configurations or different configurations.
EXPLANATIONS OF LETTERS OR NUMERALS
[0099] 1: magnetic heat pump device
[0100] 10: first MCM heat exchanger
[0101] 11: assembly
[0102] 111: passage
[0103] 12A, 12Aa to 12Al, 12B, 12Ba to 12Be: wire
[0104] 122: concave portion
[0105] 123: convex portion
[0106] 124: groove
[0107] 125: wall
[0108] 13: casing
[0109] 131: first opening
[0110] 132: second opening
[0111] 14: accommodation portion
[0112] 141: bottom portion
[0113] 142, 143: side portion
[0114] 144: opening
[0115] 15: lid portion
[0116] 17: first terminal member
[0117] 171: first connection port
[0118] 18: second terminal member
[0119] 181: second connection port
[0120] 20: second MCM heat exchanger
[0121] 21: assembly
[0122] 22A: wire
[0123] 23: casing
[0124] 271: first connection port
[0125] 281: second connection port
[0126] 30: piston
[0127] 35: actuator
[0128] 40: permanent magnet
[0129] 50: low temperature side heat exchanger
[0130] 60: high temperature side heat exchanger
[0131] 70: rotary pump
[0132] 81 to 82: first and second low temperature side pipes
[0133] 83 to 84: third and fourth high temperature side pipes
[0134] 90: switching valve
* * * * *