U.S. patent application number 12/393849 was filed with the patent office on 2009-09-03 for magnetic material for magnetic refrigeration apparatus, amr bed, and magnetic refrigeration apparatus.
Invention is credited to Shiori Kaji, Tadahiko Kobayashi, Akiko Saito.
Application Number | 20090217674 12/393849 |
Document ID | / |
Family ID | 41012133 |
Filed Date | 2009-09-03 |
United States Patent
Application |
20090217674 |
Kind Code |
A1 |
Kaji; Shiori ; et
al. |
September 3, 2009 |
MAGNETIC MATERIAL FOR MAGNETIC REFRIGERATION APPARATUS, AMR BED,
AND MAGNETIC REFRIGERATION APPARATUS
Abstract
There are provided a magnetic material for a magnetic
refrigeration apparatus, which improves magnetic refrigeration
efficiency by the wide operation temperature range of it, AMR bed
using the magnetic material, and a magnetic refrigeration
apparatus. The magnetic material is used for the magnetic
refrigeration apparatus using a liquid refrigerant, formed by
approximately uniformly blending at least two kinds of magnetic
particles having different magnetic transition temperatures, and
the magnetic particles exhibit an approximately spherical shape
with maximum diameter of 0.3 mm or more to 2 mm or less. The AMR
bed is filled with the magnetic particles.
Inventors: |
Kaji; Shiori; (Kanagawa,
JP) ; Saito; Akiko; (Kanagawa, JP) ;
Kobayashi; Tadahiko; (Kanagawa, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
41012133 |
Appl. No.: |
12/393849 |
Filed: |
February 26, 2009 |
Current U.S.
Class: |
62/3.1 |
Current CPC
Class: |
F25B 21/00 20130101;
Y02B 30/00 20130101; F25B 2321/0021 20130101; Y02B 30/66 20130101;
H01F 1/015 20130101 |
Class at
Publication: |
62/3.1 |
International
Class: |
F25B 21/00 20060101
F25B021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2008 |
JP |
2008-047663 |
Claims
1. A magnetic material for a magnetic refrigeration apparatus
comprising: first magnetic particles contained in a heaviest
weight; and second magnetic particles contained in a next heaviest
weight having a different magnetic transition temperature from that
of the first magnetic particles, wherein, both of the magnetic
particles are blended approximately uniformly and exhibit an
approximately spherical shape with a maximum diameter of 0.3 mm or
more to 2 mm or less.
2. The material according to claim 1, wherein; the difference
between the magnetic transition temperature of first and second
magnetic particles is 1 K or more to less than 10 K; and the first
magnetic particles are blended with the second magnetic particles
at a weight ratio from 5:5 to 3:2.
3. The material according to claim 1, wherein the difference
between the magnetic transition temperature of first and second
magnetic particles is 10 K or more to 15 K or less; and the first
magnetic particles are blended with the second magnetic particles
at a weight ratio from 5:5 to 3:1.
4. The material according to claim 1, wherein the magnetic
particles are Gd (gadolinium) or GdR alloys (R: rear earth
elements).
5. AMR bed filled with a magnetic material for a magnetic
refrigeration apparatus, wherein the magnetic material comprises
first magnetic particles contained in a heaviest weight and second
magnetic particles contained in a next heaviest weight having a
different magnetic transition temperature from that of the first
magnetic particles, and both of the magnetic particles are blended
approximately uniformly and exhibit an approximately spherical
shape with a maximum diameter of 0.3 mm or more to 2 mm or
less.
6. The AMR bed according to claim 5, wherein a void ratio of the
AMR bed is 30% or more to 50% or less.
7. The AMR bed according to claim 5, wherein: the difference
between the magnetic transition temperature of first and second
magnetic particles is 1 K or more to less than 10 K; and the first
magnetic particles are blended with the second magnetic particles
at a weight ratio from 5:5 to 3:2.
8. The AMR bed according to claim 5, wherein: the difference
between the magnetic transition temperature of first and second
magnetic particles is 10 K or more to 15 K or less; and the first
magnetic particles are blended with the second magnetic particles
at a weight ratio from 5:5 to 3:1.
9. The AMR bed according to claim 5, wherein the magnetic particles
are Gd (gadolinium) or GdR alloys (R: rear earth elements).
10. A magnetic refrigeration apparatus using a liquid refrigerant
comprising: AMR bed filled with a magnetic material; magnetic field
generation device for applying and removing a magnetic field to and
from the magnetic material; a cooling block; a radiating block; and
a refrigerant flow path formed by connecting the AMR bed, the
cooling block and the radiating block configured to circulate the
liquid refrigerant, wherein the magnetic material comprises first
magnetic particles contained in a heaviest weight and second
magnetic particles contained in a next heaviest weight having a
different magnetic transition temperature from that of the first
magnetic particles, and both of the magnetic particles are blended
approximately uniformly and exhibit an approximately spherical
shape with a maximum diameter of 0.3 mm or more to 2 mm or
less.
11. The apparatus according to claim 10, wherein: the difference
between the magnetic transition temperature of first and second
magnetic particles is 1 K or more to less than 10 K; and the first
magnetic particles are blended with the second magnetic particles
at a weight ratio from 5:5 to 3:2.
12. The apparatus according to claim 10, wherein: the difference
between the magnetic transition temperature of first and second
magnetic particles is 10 K or more to 15 K or less; and the first
magnetic particles are blended with the second magnetic particles
at a weight ratio from 5:5 to 3:1.
13. The apparatus according to claim 10, wherein the magnetic
particles are Gd (gadolinium ) or GdR alloys (R: rear earth
elements).
14. The apparatus according to claim 10, wherein a void ratio of
the AMR bed is 30% or more to 50% or less.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Applications No. 2008-047663, filed
on Feb. 28, 2008, the entire contents of which are incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a magnetic material having
a magnetocaloric effect and used for a magnetic refrigeration
apparatus, AMR bed using the magnetic material, and the magnetic
refrigeration apparatus.
BACKGROUND OF THE INVENTION
[0003] At present, a refrigeration technology in a room temperature
region which closely relates to a human daily life, for example, a
refrigerator, a freezer, a room air conditioner, and the like,
almost employs a gas compression/expansion cycle. However, as to
the gas compression/expansion cycle, a serious problem of
environmental destruction is caused by specific freon gases
discharged into the environment, and CFC's substitutes also have a
problem of an adverse affect to the environment. From the above
background, researches on the use of natural refrigerants
(CO.sub.2, ammonia, and the like) and isobutane which have little
environmental risk and the like are carried out. Thus, it is
required to put the refrigeration technologies, which have no
environmental problems and work safety and efficiency, to practice
use.
[0004] A magnetic refrigeration is one of the promising technology,
in terms of environment-friendliness and high efficiency. And a
magnetic refrigeration technology in a room temperature region is
actively researched and developed. The magnetic refrigeration
technology uses a magnetocaloric effect that Warburg discovered on
iron (Fe) in 1881. The magnetocaloric effect is a phenomenon that
the temperature of magnetic material changes according to changing
of external magnetic field in an adiabatic state. In early 1900's,
the refrigeration system using paramagnetic salts and compounds
represented by Gd.sub.2(SO.sub.4).sub.3.8H.sub.2O or
Gd.sub.3Ga.sub.5O.sub.12, which show the magnetocaloric effect, was
developed. However that system was mainly used in an ultracold
temperature region around 20 K or less, and needed a high magnetic
field around 10 T which is created by a superconducting magnet.
[0005] In 1970's and thereafter, researches making use of magnetic
transition between a paramagnetic state and a ferromagnetic state
in a ferromagnetic material have been actively carried out up to
now to realize magnetic refrigeration in a high temperature region.
As a result of these researches, some magnetic materials are
proposed. For example, a simple substance of rare earth (Pr, Nd,
Dy, Er, Tm, Gd and the like), rare earth alloys which include at
least two kinds of rare earth element, such as Gd--Y, Gd--Dy, and
intermetallic compounds such as RAl.sub.2 and RNi.sub.2 (R
represents rare earth elements), GdPd, and the like.
[0006] In 1982, Barclay proposed an AMR ("Active Magnetic
Regenerative Refrigeration") system as a magnetic refrigeration
system for a room temperature region in the United States. The key
feature of this system is to use the two effect, a magnetocaloric
effect and a heat accumulation, of magnetic materials (refer to
U.S. Pat. No. 4,332,135). That is, this system actively uses the
lattice entropy which was conventionally considered as a
disincentive.
[0007] Magnetic refrigeration is carried out by the AMR system
using the following steps:
[0008] (1) A magnetic field is applied to a magnetic refrigeration
working material;
[0009] (2) The magnetic refrigeration working material heat up at
step (1) and this heat energy is transported to one side by a heat
transfer fluid;
[0010] (3) The magnetic field removed; and
[0011] (4) The magnetic refrigeration working materials cool down
at step (3) and this cold energy is transported to the other side
by a heat transfer fluid.
[0012] Repeating the cycle from (1) to (4), the heat energy
generated by magnetic refrigeration material is transported to one
direction and then the temperature gradient is created in AMR bed.
As a result, a refrigeration work is carried out by generating a
large temperature difference.
[0013] In United States in 1998, Zimm, Gschneidner, Pecharsky et al
succeeded in a continuous operation of a magnetic refrigeration
cycle by using AMR systems with Gd (gadolinium) under the high
magnetic field (5 T) generated by a superconducting magnet.
[0014] Incidentally, since the magnetocaloric effect of the
magnetic refrigeration material can obtain a large effect only in
the vicinity of a magnetic transition temperature, a problem arises
in that the working efficiency is lowered when temperature is
shifted from the magnetic transition temperature of the material.
To cope with the above problem, it is proposed to increase a
working temperature by filling AMR bed with magnetic materials
having different magnetic transition temperatures in a layer state
in accordance with a temperature difference generated in the AMR
bed (JP-A 4-186802 (KOKAI)).
SUMMARY OF THE INVENTION
[0015] A magnetic material for a magnetic refrigeration apparatus
using a liquid refrigerant of an embodiment of the present
invention includes at least two kinds of magnetic particles having
different magnetic transition temperatures and blended
approximately uniformly, wherein, the magnetic particles exhibit an
approximately spherical shape with a maximum diameter of 0.3 mm or
more to 2 mm or less.
[0016] In AMR bed filled with a magnetic material for a magnetic
refrigeration apparatus using a liquid refrigerant of an embodiment
of the present invention, the magnetic material includes at least
two kinds of magnetic particles having different magnetic
transition temperatures and blended approximately uniformly, and
the magnetic particles exhibit an approximately spherical shape
with a maximum diameter of 0.3 mm or more to 2 mm or less.
[0017] A magnetic refrigeration apparatus using a liquid
refrigerant of an embodiment of the present invention has AMR bed
filled with a magnetic material, a magnetic field generation device
for applying and removing a magnetic field to and from the magnetic
material, a cooling block, a radiating block, and a refrigerant
flow path connected to the AMR bed, the cooling block and the
radiating block configured to circulate the liquid refrigerant,
wherein the magnetic material includes at least two kinds of
magnetic particles having different magnetic transition
temperatures and blended approximately uniformly, and the magnetic
particles exhibit an approximately spherical shape with a maximum
diameter of 0.3 mm or more to 2 mm or less.
[0018] According to the present invention, there can be provided a
magnetic material for a magnetic refrigeration apparatus which
improves magnetic refrigeration efficiency by the wide operation
temperature range of it and the magnetic refrigeration apparatus
using the magnetic material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is an explanatory view showing an operation of a
magnetic material for a magnetic refrigeration apparatus of a first
embodiment;
[0020] FIG. 2 is a schematic view of a system of a magnetic
refrigeration apparatus of a second embodiment;
[0021] FIG. 3 is a sectional view showing an arrangement of a
magnetic material in AMR bed of the second embodiment;
[0022] FIG. 4 is a sectional view showing another arrangement of
the magnetic material in AMR bed of a third embodiment;
[0023] FIG. 5 is a graph showing a result of measurement of a
refrigerating operation temperature range of examples and
comparative examples; and
[0024] FIG. 6 is a graph showing a result of measurement of the
refrigerating operation temperature range of the examples and the
comparative examples.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] The inventors have found that when at least two kinds of
magnetic particles having different magnetic transition
temperatures (Tc) are approximately uniformly blended and AMR bed
is filled with them, a magnetic refrigeration operation temperature
range can be extended without outstandingly lowering a
refrigeration capability. A magnetic material for a magnetic
refrigeration apparatus, AMR bed, and the magnetic refrigeration
apparatus of embodiments of the present invention will be explained
below referring to the drawings based on the above knowledge found
by the inventors. Note that, in the specification, two kinds of
magnetic particles have different magnetic transition temperatures
means that the average values of the magnetic transition
temperatures of respective magnetic particles are separated from
each other 0.5 K or more.
First Embodiment
[0026] A magnetic material for a magnetic refrigeration apparatus
of a first embodiment is a magnetic material for a magnetic
refrigeration apparatus using a liquid refrigerant. At least two
kinds of magnetic particles having different magnetic transition
temperatures (Tc) are approximately uniformly blended. The magnetic
particles exhibit an approximately spherical shape with a maximum
diameter of 0.3 mm or more to 2 mm or less.
[0027] In the magnetic material of the first embodiment, two kinds
of magnetic particles, for example, Gd particles having a magnetic
transition temperature 293 (K) and Gd.sub.95Y.sub.5 particles
having a magnetic transition temperature 283 (K), which is lower
than that of the Gd particles, are approximately uniformly blended
at a ratio of 1:1. Hereinafter, the difference between the magnetic
transition temperatures of the two kinds of the magnetic particles
is called a magnetic transition temperature difference
(.DELTA.Tc).
[0028] The two kinds of the magnetic particles exhibit the
approximately spherical shape with the maximum diameter of 0.3 mm
or more to 2 mm or less. The maximum diameter of the magnetic
particles can be visually measured with a calipers and the like, by
direct observation under a microscope, or by a microscope
photograph.
[0029] Note that it is possible to use compounds, in which Gd is
combined with Y having different composition ratios, or GdR (R
shows rear earth elements other than Gd, Y, i.e., Sc, La, Ce, Pr,
Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu) as the magnetic
particles in addition to Gd.sub.95Y.sub.5 and Gd described above.
Further, for example, compounds composed of various kinds of rear
earth elements and transition metal elements, NiMnGa alloys, GdGeSi
alloys, LaFe.sub.13 compounds, LaFe.sub.13H, MnAsSb, and the like
can be used.
[0030] FIG. 1 is an explanatory view showing an operation of the
magnetic material for the magnetic refrigeration apparatus of the
first embodiment. An upper view of FIG. 1 is a graph showing the
relation between the temperature of the magnetic material and a
refrigeration temperature difference (.DELTA.T) of the magnetic
material. Further, a lower view of FIG. 1 is a conceptual view
showing how AMR bed is filled with magnetic materials and the
magnetic refrigeration operation temperature ranges to the
respective magnetic material by arrows in correspondence to a
temperature axis of the upper view of FIG. 1. Note that the
refrigeration temperature difference (.DELTA.T) means a temperature
difference caused to the magnetic material when a magnetic field is
repeatedly applied and removed to and from the magnetic material
and used as an index of the refrigeration capability of the
magnetic material.
[0031] In the upper view of FIG. 1, when magnetic particles A and
magnetic particles B, which have two kinds of different magnetic
transition temperatures and the refrigeration temperature
characteristics of which are shown by two broken lines, are
blended, a magnetic refrigerating operation temperature is
increased without outstandingly lowering the refrigeration
capability as shown by a solid line (actually measured) of the
upper view of FIG. 1. In general, when the magnetic particles A and
B having the two kinds of the different magnetic transition
temperatures are blended, it is predicted that the refrigeration
capability is lowered although the magnetic refrigerating operation
temperature is increased as shown by a single-dashed line
(predicted) of the upper view of FIG. 1.
[0032] A reason why the refrigeration capability is not
outstandingly lowered against prediction in the first embodiment is
considered as described below. That is, at a certain temperature, a
temperature change caused by application and removal of the
magnetic field is determined depending on materials. Accordingly,
it is considered that when all the materials are the same
materials, the same temperature change ideally occurs all at once.
However, when different materials exist, since dispersion occurs in
the temperature change caused by application of the magnetic field,
heat is transmitted between the magnetic materials. Since heat is
secondarily generated and absorbed by the transmission of heat, a
temperature change, which is not caused when the same kind of a
material is used, occurs. As a result, it is considered that an
effect of an increase of temperature, which cannot be predicted
from measurement of the simple material appears. The operation
temperature can be increased without outstandingly lowering the
refrigeration capability by the addition of the above effect
resulting from the blend.
[0033] The magnetic particles exemplified above have different
magnetic transition temperatures depending on the compositions
thereof. In the magnetic material of the first embodiment, a wide
range of the refrigeration operation temperature can be guaranteed
by appropriately combining two kinds of magnetic particles having
appropriate magnetic transition temperatures. Although the example,
in which the two kinds of the magnetic particles having the
different magnetic transition temperatures are blended, is
explained here, three kinds or more of magnetic particles may be
blended.
[0034] As described above, the magnetic particles of the first
embodiment exhibit the approximately spherical shape with the
maximum diameter of 0.3 mm or more to 2 mm or less. It is important
for the magnetic refrigeration apparatus to realize a high
refrigeration capability in that a magnetic material with which the
AMR bed is filled sufficiently exchanges its heat with a liquid
refrigerant and realizes high heat exchange efficiency. For this
purpose, it is preferable to increase the specific surface area of
magnetic particles by increasing the particle diameter thereof. In
contrast, when the particle diameter is too small, a refrigerant
pressure loss is increased. Accordingly, the refrigeration
capability of a magnetic refrigeration apparatus is improved by
using the magnetic particles of the first embodiment whose maximum
diameter is set to 0.3 mm or more to 2 mm or less.
[0035] As described above, the magnetic material of the first
embodiment can extend the magnetic refrigeration operation
temperature range without outstandingly lowering the refrigeration
capability as compared with a magnetic material composed of simple
magnetic particles. Further, when the magnetic material is combined
with the liquid refrigerant, high heat exchange efficiency can be
realized. Accordingly, the refrigeration capability of the
refrigeration apparatus can be improved by filling the AMR bed with
the magnetic material of the first embodiment and applying the AMR
bed to the refrigeration apparatus.
[0036] Further, in the first embodiment, it is preferable to blend
magnetic particles, which make use of secondary magnetic transition
without hysteresis, with each other. This is because it is
considered that heat is effectively transmitted between magnetic
materials and an effect of suppressing a lowering of the
refrigeration capability can be increased.
[0037] Note that, in the first embodiment, even if particles other
than the magnetic particles for exhibiting the advantage of the
first embodiment are contained as impurities in an amount of
several percentages to the total weight of the magnetic material,
they do not inhibit the advantage of the first embodiment.
Second Embodiment
[0038] A magnetic refrigeration apparatus of a second embodiment is
a magnetic refrigeration apparatus using a liquid refrigerant. The
magnetic refrigeration apparatus has AMR bed filled with a magnetic
material, a magnetic field generation means (device) for applying
and removing a magnetic field to and from the magnetic material, a
cooling block, and a radiating block. Further, the magnetic
refrigeration apparatus has a refrigerant flow path formed by
connecting the AMR bed, the cooling block and the radiating block
configured to circulate the liquid refrigerant. The magnetic
material with which the AMR bed is filled is formed by
approximately uniformly bending at least two kinds of magnetic
particles having different magnetic transition temperatures, and
the magnetic particles has a feature in that they exhibit an
approximately spherical shape with a maximum diameter of 0.3 mm or
more to 2 mm or less. Note that since the magnetic material with
which the AMR bed is filled is the same as that described in the
first embodiment, description of duplicate contents is omitted.
[0039] FIG. 2 is a schematic view of a system of the magnetic
refrigeration apparatus of the second embodiment. The magnetic
refrigeration apparatus uses, for example, water as the liquid
refrigerant. The cooling block 20 is disposed to a low temperature
end side of the AMR bed 10, and the radiating block 30 is disposed
to a high temperature end side thereof. A switching means 40 is
interposed between the cooling block 20 and the radiating block 30
to switch a direction in which the liquid refrigerant flow.
Further, a refrigerant pump 50 as a refrigerant transport means is
connected to the switching means 40. The AMR bed 10, the cooling
block 20, the switching means 40, and the radiating block 30 are
connected by a pipe and form the refrigerant flow path for
circulating the liquid refrigerant.
[0040] The AMR bed 10 is filled with the magnetic material 12
having a magnetocaloric effect. A horizontally movable permanent
magnet 14 is disposed to outside of the AMR bed 10 as a magnetic
field generation means. The cooling block 20 is composed of a
low-temperature bath 22, in which a low temperature side heat
exchanger device 24 is disposed, and a cooling unit 26. The low
temperature side heat exchanger device 24 is thermally connected to
the cooling unit 26. In contrast, the radiating block 30 is
composed of a hot bath 32, in which a high temperature side heat
exchanger device 34 is disposed, and a radiating unit 36. The high
temperature side heat exchanger device 34 is thermally connected to
the radiating unit 36.
[0041] Although the magnetic refrigeration apparatus of the second
embodiment is not particularly limited, it is, for example, a home
freezer/refrigerator, a home air conditioner, an industrial
freezer/refrigerator, a large frozen/refrigerated warehouse, a
frozen chamber for reserving and transporting a liquefied gas, and
the like.
[0042] When, for example, the magnetic refrigeration apparatus is
the home freezer/refrigerator, the cooling unit is a
freezing/refrigerating chamber, and the radiating unit 36 is, for
example, a radiation plate.
[0043] FIG. 3 is a sectional view showing an arrangement of a
magnetic material in the AMR bed. As shown in the figure, the AMR
bed 10 is filled with a magnetic material having the magnetocaloric
effect. The magnetic material is a magnetic material formed by
approximately uniformly blending two kinds of magnetic particles,
for example, Gd particles 16 and Gd.sub.95Y.sub.5 particles 15
having a magnetic transition temperature lower than that of the Gd
particles 16. Openings are formed to both the ends of the AMR bed
10 so that a refrigerant is caused to flow in both right and left
directions in the AMR bed 10.
[0044] Next, an operation of the magnetic refrigeration apparatus
of the second embodiment will be schematically explained using FIG.
2. When the permanent magnet 14 is disposed at a position
confronting with the AMR bed 10 (position shown in FIG. 2), a
magnetic field is applied to the magnetic material 12 in the AMR
bed 10. Accordingly, the magnetic material 12 having the
magnetocaloric effect generates heat. At the time, the liquid
refrigerant is caused to circulate in the direction from the AMR
bed 10 to the radiating block 30 by the operations of the
refrigerant pump 50 and the switching means 40. Hot heat is
transported to the radiating block 30 by the liquid refrigerant
whose temperature is increased by the heat generated by the
magnetic material 12. Then, the liquid refrigerant flows into the
hot bath 32 in the radiating block 30, and the hot heat transported
by the refrigerant is absorbed by the high temperature side heat
exchanger device 34. The absorbed hot heat is radiated to, for
example, the outside air by the radiating unit 36.
[0045] Thereafter, the permanent magnet 14 is moved from the
position confronting with the AMR bed 10, and the magnetic field
applied to the magnetic material 12 is removed. When the magnetic
field is removed, the magnetic material 12 absorbs heat. At the
time, the liquid refrigerant is caused to circulate in the
direction from the AMR bed 10 to the cooling block 20 by the
operations of the refrigerant pump 50 and the switching means 40.
Cold heat is transported to the cooling block 20 by the liquid
refrigerant that is cooled by the heat absorbed by magnetic
material 12. The liquid refrigerant flows into the low-temperature
bath 22 in the cooling block 20, and the cold heat transported by
the refrigerant is absorbed by the low temperature side heat
exchanger device 24. The cooling unit 26 is cooled by the cold
heat.
[0046] The cooling unit 26 can be continuously cooled by repeating
application and removal of the magnetic field to and from the
magnetic material 12 in the AMR bed 10 by repeatedly moving the
permanent magnet 14.
[0047] The magnetic refrigeration apparatus of the second
embodiment can realize high heat exchange efficiency by using the
magnetic material whose magnetic refrigerating operation
temperature is increased without outstandingly lowering a
refrigeration capability.
[0048] Note that the arrangement of the magnetic material in the
AMR bed is not necessarily limited to the arrangement shown in FIG.
3. FIG. 4 is a sectional view showing another arrangement of the
magnetic material in the AMR bed. As shown in FIG. 4, the AMR bed
10 is filled with a magnetic material, in which magnetic particles
A and B having two kinds of different magnetic transition
temperatures are blended, on the low temperature end side thereof.
Then, the AMR bed 10 is filled with a magnetic material, in which
magnetic particles C and D having two kinds of different magnetic
transition temperatures are blended, on the high temperature end
side thereof. The magnetic material on the low temperature end side
are separated from that on the high temperature end side by, for
example, a lattice-shaped partition wall 18 in which a refrigerant
can flow so that they are not blended with each other.
[0049] The magnetic particles A, the magnetic particles B, the
magnetic particles C, the magnetic particles D, and the blend ratio
thereof are determined so that the magnetic material on the low
temperature side have a refrigeration operation temperature range
lower than that of the magnetic material on the high temperature
side.
[0050] The magnetic refrigerating operation temperature can be more
increased and a magnetic refrigeration apparatus that realizes
higher heat exchange efficiency can be provided by employing the
arrangement of the magnetic materials in the AMR bed shown in FIG.
4.
[0051] Note that although the case, in which the magnetic materials
in the AMR bed have a laminated structure having two layers, is
shown in FIG. 4, the magnetic refrigerating operation temperature
can be more increased by providing a layered structure having three
or more layers.
[0052] Further, the void ratio of the AMR bed filled with the
magnetic materials is preferably 30% or more to 50% or less. In AMR
bed filled with magnetic particles for a magnetic refrigeration
apparatus using a liquid refrigerant, it is preferable to form a
sufficient amount of void space through which a fluid flows so that
the flow of the liquid refrigerant is not inhibited in the AMR bed.
When the void ratio is less than 30%, since a pressure loss is
excessively increased, there is a possibility that refrigeration
efficiency is lowered. Further, when the void ratio exceeds 50%,
since the magnetic particles that contribute to a refrigerating
operation are reduced, there is possibility that a sufficient
refrigeration capability cannot be obtained. Note that the void
ratio is a value defined by the mass ratio of the mass of a
magnetic material equivalent to the volume of AMR bed and the mass
of a magnetic material with which the AMR bed is filled.
[0053] The embodiments of the present invention have been explained
above referring to the specific examples. However, the above
embodiments are exemplified as only examples and do not restrict
the present invention. Further, in the explanation of the
embodiments, although the explanation of the components in the
magnetic material for the magnetic refrigeration apparatus, the AMR
bed, the magnetic refrigeration apparatus, and the like, which are
not directly necessary to the explanation of the present invention,
is omitted, necessary components, which relate to the magnetic
material for the magnetic refrigeration apparatus, the magnetic
refrigeration apparatus, and the like, can be appropriately
selected and used.
[0054] In addition to the above-mentioned, all the magnetic
material for the magnetic refrigeration apparatus, the AMR bed, and
the magnetic refrigeration apparatus, which have the components of
the present invention and the design of which can be appropriately
modified by persons skilled in the art, are included in the scope
of the present invention. The scope of the present invention is
defined by the scope of the appended claims and the scope of the
equivalents thereof.
EXAMPLES
[0055] Examples of the present invention will be explained below in
detail.
Example 1
[0056] AMR bed (hereinafter, called also a specimen vessel) was
filled with a specimen, in which Gd.sub.95Y.sub.5 particles and Gd
particles formed in a spherical shape and having a diameter of 0.3
mm or more to 2 mm or less were blended at a weight ratio of 3:1
(Gd ratio=25%), at a void ratio of 30% to 50%, and a refrigeration
temperature difference (.DELTA.T) was evaluated. Note that the
magnetic transition temperature of the Gd.sub.95Y.sub.5 particles
was 283 K, the magnetic transition temperature of the Gd particles
was 293 K, and a magnetic transition temperature difference
(.DELTA.Tc) was 10 K. The refrigeration temperature difference
(.DELTA.T) was evaluated by the following method.
[0057] The AMR bed was filled with the specimen so that the
specimen did not easily move. Next, a thermocouple was inserted
into the specimen vessel through a 0.8 mm .phi. hole formed to an
upper lid of the vessel so that it was positioned in a central
portion of the specimen vessel. Further, the specimen vessel was
entirely covered with a heat insulating material and fixed to a
specimen holder in a constant temperature bath. The specimen holder
was located at a position at which it was possible to apply and
remove a magnetic field by the operation of yoke magnet,and it was
possible to adjust the internal temperature of the constant
temperature bath from the outside. After the inside of the constant
temperature bath was shut off from the outside, the temperature of
the inside thereof was adjust, and it was waited that the inside
temperature thereof was made uniform. Thereafter, the magnetic
field was repeatedly applied and removed to and from the specimen
by operating the yoke magnet, and .DELTA.T was measured by a
temperature difference at the time. Subsequently, after the
temperature in the constant temperature bath was adjusted, .DELTA.T
at the respective temperatures of the specimen was evaluated by
repeating a process of measuring the temperature dependence of
.DELTA.T by applying and removing the magnetic field to and from
the specimen.
[0058] As a result of the measurement, the temperature range which
satisfies .DELTA.T.gtoreq.1.6 K was set as the magnetic
refrigeration operation temperature range of the specimen. The
condition of .DELTA.T.gtoreq.1.6 K is a condition by which the
superiority of the magnetic material is verified by the
refrigeration test performance in the AMR system obtained up to
that time. Table 1 shows an obtained result.
Example 2
[0059] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.95Y.sub.5 particles and Gd
particles were blended at a weight ratio of 1:1 (Gd ratio=50%), was
prepared.
Example 3
[0060] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.95Y.sub.5 particles and Gd
particles were blended at a weight ratio of 1:3 (Gd ratio=75%), was
prepared.
Comparative Example 1
[0061] The same evaluation as that of the example 1 was executed
except that a specimen of simple Gd.sub.95Y.sub.5 particles was
prepared.
Example 4
[0062] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.97Y.sub.3 particles and Gd
particles were blended at a weight ratio of 3:1 (Gd ratio=25%), was
prepared. Note that the magnetic transition temperature of the
Gd.sub.97Y.sub.3 particles was 287 K, the magnetic transition
temperature of the Gd particles was 293 K, and a magnetic
transition temperature difference (.DELTA.Tc) was 6 K.
Example 5
[0063] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.97Y.sub.3 particles and Gd
particles were blended at a weight ratio of 3:2 (Gd ratio=40%), was
prepared.
Example 6
[0064] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.97Y.sub.3 particles and Gd
particles were blended at a weight ratio of 1:1 (Gd ratio=50%), was
prepared.
Example 7
[0065] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.97Y.sub.3 particles and Gd
particles were blended at a weight ratio of 2:3 (Gd ratio=60%), was
prepared.
Example 8
[0066] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.97Y.sub.3 particles and Gd
particles were blended at a weight ratio of 1:3 (Gd ratio=75%), was
prepared.
Comparative Example 2
[0067] The same evaluation as that of the example 1 was executed
except that a specimen of simple Gd.sub.97Y.sub.3 particles was
prepared.
Example 9
[0068] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.98Y.sub.2 particles and Gd
particles were blended at a weight ratio of 3:2 (Gd ratio=40%), was
prepared. Note that the magnetic transition temperature of the
Gd.sub.98Y.sub.2 particles was 289 K, the magnetic transition
temperature of the Gd particles was 293 K, and the magnetic
transition temperature difference (.DELTA.Tc) was 4 K.
Example 10
[0069] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.98Y.sub.2 particles and Gd
particles were blended at a weight ratio of 1:1 (Gd ratio=50%), was
prepared.
Example 11
[0070] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.98Y.sub.2 particles and Gd
particles were blended at a weight ratio of 2:3 (Gd ratio=60%), was
prepared.
Example 12
[0071] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.98Y.sub.2 particles and Gd
particles were blended at a weight ratio of 1:3 (Gd ratio=75%), was
prepared.
Comparative Example 3
[0072] The same evaluation as that of the example 1 was executed
except that a specimen of simple Gd.sub.98Y.sub.2 particles was
prepared.
Example 13
[0073] The same evaluation as that of the example 1 was executed
except that a specimen, in which Gd.sub.98.5Y.sub.1.5 particles and
Gd particles were blended at a weight ratio of 1:1 (Gd ratio=50%),
was prepared. Note that the magnetic transition temperature of the
Gd.sub.98.5Y.sub.1.5 particles was 290 K, the magnetic transition
temperature of the Gd particles was 293 K, and the magnetic
transition temperature difference (.DELTA.Tc) was 3 K.
Comparative Example 4
[0074] The same evaluation as that of the example 1 was executed
except that a specimen of simple Gd.sub.98.5Y.sub.1.5 particles was
prepared.
TABLE-US-00001 TABLE 1 Refrigerating operation Gd temperature
Magnetic blending range (K) Sample Material ratio (%) when T
.gtoreq. 1.6K Tc (K) Example 1 Gd.sub.95Y.sub.5 + Gd 25 18.3 10
Example 2 Gd.sub.95Y.sub.5 + Gd 50 18.6 10 Example 3
Gd.sub.95Y.sub.5 + Gd 75 18.3 10 Comparative Gd.sub.95Y.sub.5 0
10.7 -- Example 1 Example 4 Gd.sub.97Y.sub.3 + Gd 25 15.6 6 Example
5 Gd.sub.97Y.sub.3 + Gd 40 19.0 6 Example 6 Gd.sub.97Y.sub.3 + Gd
50 19.6 6 Example 7 Gd.sub.97Y.sub.3 + Gd 60 17.8 6 Example 8
Gd.sub.97Y.sub.3 + Gd 75 15.7 6 Comparative Gd.sub.97Y.sub.3 0 13.1
-- Example 2 Example 9 Gd.sub.98Y.sub.2 + Gd 40 17.0 4 Example 10
Gd.sub.98Y.sub.2 + Gd 50 17.2 4 Example 11 Gd.sub.98Y.sub.2 + Gd 60
18.0 4 Example 12 Gd.sub.98Y.sub.2 + Gd 75 16.5 4 Comparative
Gd.sub.98Y.sub.2 0 15.9 -- Example 3 Example 13
Gd.sub.98.5Y.sub.1.5 + Gd 50 20.0 3 Comparative
Gd.sub.98.5Y.sub.1.5 0 17.2 -- Example 4
[0075] It is apparent from the results of the examples 1 to 3 and
the comparative example 1 that the refrigeration operation
temperature range of .DELTA.T.gtoreq.1.6 K, which was only 10.7 K
in the simple Gd.sub.95Y.sub.5 particles, was increased by about 8
K by adding the Gd particles. FIG. 5 is a graph in which the
results of the examples 1 to 3 and the comparative example 1 are
plotted. In the examples 1 to 3 in which the magnetic transition
temperature difference (.DELTA.Tc) was 10 K, when the Gd ratio was
25% to 75%, that is, when the weight ratio of first magnetic
particles, which have a heaviest weight in contained magnetic
materials, and second magnetic particles, which have a next
heaviest weight in contained materials, was 5:5 to 3:1, a
particularly wide refrigeration operation temperature range could
be obtained.
[0076] It is apparent from the results of the examples 4 to 8 and
the comparative example 2 that the refrigeration operation
temperature range of .DELTA.T.gtoreq.1.6 K, which was only 13.1 K
in the simple Gd.sub.97Y.sub.3 particles, was increased by about
6.5 K by adding the Gd particles. FIG. 6 is a graph in which the
results of the examples 4 to 8 and the comparative example 2 are
plotted. In the examples 4 to 8 in which the magnetic transition
temperature difference (.DELTA.Tc) was 6 K, when the Gd ratio was
40 to 60%, that is, when the weight ratio of first magnetic
particles, which have a heaviest weight in contained magnetic
materials, and second magnetic particles, which have a next
heaviest weight in contained materials, was 5:5 to 3:2, a
particularly wide refrigeration operation temperature range could
be obtained.
[0077] It is apparent from the results of the examples 9 to 12 and
the comparative example 3 that the refrigeration operation
temperature range of .DELTA.T.gtoreq.1.6 K, which was only 15.9 K
in the simple Gd.sub.98Y.sub.2 particles, was increased by about
2.1 K at most by adding the Gd particles. Further, in the examples
9 to 12 in which the magnetic transition temperature difference
(.DELTA.Tc) was 4 K, when the Gd ratio was 40 to 60%, that is, when
the weight ratio of first magnetic particles, which have a heaviest
weight in contained magnetic materials, and second magnetic
particles, which have a next heaviest weight in contained
materials, was 5:5 to 3:2, a particularly wide refrigeration
operation temperature range could be obtained.
[0078] It is apparent from the results of the example 13 and the
comparative example 4 that the refrigeration operation temperature
range of .DELTA.T.gtoreq.1.6 K, which was only 17.2 K in the simple
Gd.sub.98Y.sub.2 particles, was increased by about 2.8 K by adding
the Gd particles. Further, in the example 13 in which the magnetic
transition temperature difference (.DELTA.Tc) was 3 K, when the Gd
ratio was 50%, that is, when the weight ratio of first magnetic
particles, which have a heaviest weight in contained magnetic
materials, and second magnetic particles, which have a next
heaviest weight in contained materials, was 5:5, the refrigeration
operation temperature range could be increased.
[0079] As described above, the advantage of the present invention
is confirmed by the examples.
* * * * *