JPH0792286B2 - refrigerator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator provided with a low temperature heat storage device filled with a heat storage material.

[0002]

2. Description of the Related Art In recent years, the development of superconducting technology has been remarkable, and with the expansion of its application fields, it has become indispensable to develop a small and high-performance refrigerator. Such a small refrigerator is required to be lightweight, small and have high thermal efficiency.

From the above, a new refrigeration system (magnetic refrigeration) and a star by a heat cycle (for example, Carno-Ericsson) using a magnetocaloric effect instead of gas refrigeration is used.
Researches for improving the performance of gas refrigeration by the ring cycle are being actively conducted.

In order to improve the performance of the gas refrigerator by the heat cycle such as the Stirling, improvement of the heat accumulator, the compression section and the expansion section has become an important issue. In particular, the heat storage material that constitutes the heat storage device greatly affects its performance. As such a heat storage material, a material having a high specific heat even at 20 K or less at which the specific heat of copper or lead is remarkably reduced is demanded, and various magnetic materials are also being studied for this material.

Further, the regenerator is often used by being incorporated in a refrigerator, and is used in, for example, a device that operates in a Stirling cycle, a device that operates in a Beilroy-Mille cycle, or a device of the Gifoed-McMahon type. Has been. In these devices, the compressed working medium flows in one direction in the regenerator to supply its thermal energy to the filling material, where the expanded working medium flows in the opposite direction, from the filled heat storage material. Receive heat energy. In this process, as the recuperation effect becomes better, the thermal efficiency of the working medium cycle becomes better, and it becomes possible to realize a lower temperature.

By the way, in a low temperature heat storage device, a lead or bronze ball or a copper or phosphor bronze wire mesh layer has been conventionally used as the heat storage material. However, since the specific heat of such heat storage material at an extremely low temperature of 20 K or less is too small, it is not possible to store sufficient heat energy in the heat storage material at each cycle under the extremely low temperature when operating in the refrigerator described above. Also, the working medium cannot receive sufficient heat energy from the heat storage material. As a result, there is a problem that a refrigerator incorporating a heat storage device having the heat storage material cannot reach an extremely low temperature.

From the above, in order to improve the recuperative characteristics of the above-mentioned heat storage device at extremely low temperatures, a 20 K heat storage material is used.
It has the maximum specific heat at the following temperatures, and its value is sufficiently large in specific heat per unit volume (volume specific heat).
h Intermetallic compound (R; Sm, Gd, Tb, Dy, Ho,
It has been proposed to use Er, Tm, Yb) (JP-A-51-52378). However, since such a heat storage material uses extremely expensive Rh (rhodium) as one component thereof, there is a problem in practical use as a heat storage material for a heat storage device used on the order of several hundred grams.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has a small-sized low-temperature heat storage device having excellent heat transfer characteristics and recuperation characteristics and high thermal efficiency. It is intended to provide a refrigerator.

[0009]

A refrigerator according to the present invention is a refrigerator provided with a low temperature heat storage device filled with a heat storage material so that a cooling gas can flow, wherein the heat storage material is
General formula (I) AM _z (I)

(Where A is Y, La, Ce, P
r, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
At least one rare earth element selected from o, Er, Tm, and Yb is shown, M is at least one metal selected from Ni, Co, and Cu, and z is 0.001 ≦ z ≦.
The average particle diameter is 1 to 2000.
It consists of one or more selected from the magnetic particles of μm.
And has a specific heat peak at a temperature of less than 77K . In addition, another refrigeration according to the present invention
The machine is filled so that the heat storage material can pass the cooling gas.
In a refrigerator having a cold heat accumulator, the heat storage material
Is the general formula (I) AM _z (I) (where A is Y, La, Ce, Pr, Nd, P
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
at least one rare earth element selected from m and Yb
And M is at least 1 selected from Ni, Co and Cu.
(Indicates a metal of a kind, z is 0.001 ≦ z ≦ 9.0)
And fibrous magnetic with an average diameter of 1 to 2000 μm
It consists of one or more selected from the body, and the temperature is
Characterized by having a specific heat peak below 77K
Is.

The reason why the value of z in the general formula (I) representing the composition of the magnetic material is set within the above range is as follows. When z is less than 0.001, the temperature at which the peak of specific heat reaches 77 K or higher due to direct exchange interaction between rare earth atoms. On the other hand, z is 9.0.
If it exceeds, the magnetic atom (rare earth atom density) is remarkably lowered and the magnetic specific heat is lowered.

By defining such a value of z, a magnetic material having excellent heat storage characteristics can be obtained. Also,
As z in the general formula (I), 0.01 ≦ z <2.0
Within the range, there is an advantage that the lattice specific heat on the high temperature side of the heat storage material composed of the magnetic material can be improved. This is 0.0 in the phase diagram of the rare earth element represented by A of the general formula (I) and the transition metal represented by M such as Ni.
It is presumed that the eutectic reaction is present within the range of 1 ≦ z <2.0, the melting point is significantly lowered, and as a result, excellent lattice specific heat is obtained.

As a specific example, ErNi and ErNi
_{The 1/3} spin arrangement is shown in FIGS. 1 and 2, respectively. As described above, the magnetic material in the range of 0.01 ≦ z <2.0 has a complicated spin arrangement, and the magnetic arrangement (plural exchange interactions) causes the peak of the specific heat near the magnetic transition. It has the advantage of essentially being a broad. From the practical point of view, it is desirable that the lower limit value of z in the general formula (I) is 0.01. Furthermore, the preferable upper limit of z is 1.
5, more preferably 1.0, and particularly z is 1/3 ≦ z
The effect can be remarkably exhibited by setting the range to ≦ 1.0.

The size of the granular or fibrous magnetic material is
The reason is as follows. When the average particle diameter or the average diameter of the magnetic material is less than 1 μm, when filled in the heat accumulator, it easily flows out of the heat accumulator together with the high-pressure working medium (for example, helium gas). On the other hand, when the average particle diameter or the average diameter of the magnetic material exceeds 2000 μm, the thermal conductivity of the magnetic material becomes the rate-determining factor of the heat transfer between (magnetic material) / (working medium), and the heat transfer property remarkably deteriorates. There is a risk that the heat recovery effect will be reduced.

The reason for defining the upper limit of the average particle diameter or fiber diameter of the magnetic material will be described more specifically. In order to utilize 100% of the heat capacity of the heat storage material composed of the magnetic material, a large volume specific heat ( ρCp; ρ is the density of the heat storage material, C
p is required to have high thermal conductivity commensurate with the specific heat. That is, the penetration depth (ld) that determines the effective volume of the heat storage material that contributes to heat storage is expressed by the following equation. ld = λ / (ρCpπf)

Here, λ is the thermal conductivity, ρ is the density of the heat storage material, Cp is the specific heat, and f is the frequency. For example, ρCp is 6
0.3 J / cm ³ above K When a magnetic material such as ErNi _1/3 with a large K is used, its thermal conductivity (80 mW
From the relationship with / Kcm), ld is about 600 μm.
Therefore, in this case, the heat storage material separated by 600 μm or more from the surface does not contribute to heat storage. Therefore, the upper limit of the average particle diameter or fiber diameter of ErNi _1/3 as a heat storage material is 1200 μm, preferably 1000 μm.

From the viewpoint of achieving uniform heat transfer and reduction of pressure loss by filling the spherical magnetic material regularly in the three-dimensional direction, the spherical magnetic material has a diameter within the range of the average particle diameter, and the fiber diameter described above. It is desirable to have a fibrous shape within the range. The spherical magnetic body can be manufactured, for example, by the following method. (1) A method of dropping a molten material into water or oil to solidify it, (2) A method of injecting a molten material into a turbulent flow layer of a liquid or a gas, (3) A flat material of a molten material Method of dropping or injecting onto the metal refrigerant on the top or cylinder, (4)
A method of injecting amorphous particles into an inert gas (for example, argon gas) through a heating unit (heating source).

Among the methods (1) to (4), the method (4) is practical. The heating unit in the method (4) includes thermal plasma, arc discharge plasma, infrared ray,
High-frequency induction is possible, but the plasma spray method is the most simple and practical. Further, the pressure of the inert gas in the above method (4) is preferably 1 atm or more. By setting the pressure of the inert gas to 1 atm or more, the cooling efficiency can be improved, and the molten flying object that has passed through the heating section can be solidified in a spherical state due to its surface tension.

The fibrous magnetic material is made of a woven fabric made of, for example, metal fibers such as W and B, glass fiber, carbon fiber, plastic fiber, etc., and is represented by the above general formula (I). It can be manufactured by a method of coating the above composition by vapor phase growth such as spraying or sputtering, or liquid phase growth.

The heat storage material has a composition represented by the following general formula (II) and general formula (III), and is a magnetic substance having an average particle diameter or a fiber diameter of 1 to 1000 μm.
It is preferable to use one or more kinds. ANi _z ... (II)

However, A in the formula is Y, La, Ce, P
r, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
At least one rare earth element selected from o, Er, Tm, and Yb is shown, and z is 0.001 ≦ z ≦ 9.0. A'1 _-x D _x M _z (III)

However, A'in the formula is Er, Ho, D
At least one rare earth element selected from y, Tb, and Gd is shown, D is at least one element selected from Pr, Nd, Sm, and Ce, and M is at least one selected from Ni, Co, and Cu. Of the metal, x is 0 ≦ x <
1 and z represent 0.01 ≦ z ≦ 9.0. The general formula (II)
And in (III), z is 0.1 ≦
It is preferable that z <2.0.

In the general formula (III), A'is E
By using heavy rare earth elements such as r, Ho, Dy, Tb, and Gd, particularly remarkable magnetic specific heat can be exhibited by the alloy with M such as Ni, and the maximum peak value of specific heat can be increased.
Further, by selecting a light rare earth element such as Pr, Nd, Sm, or Ce as D substituting the heavy rare earth element represented by A'in the general formula (III), the peak of specific heat is utilized by utilizing Schottky anomaly or the like. Maximum value and temperature range (half width)
Can be adjusted.

The heat storage material is allowed to be composed of one or more magnetic materials selected from the magnetic materials in which a part of M in the general formula (I) is substituted with B, Al, Ga, In, Si or the like. . The compositions of such magnetic materials are shown below as general formulas (IV) and (V). A (M _1-y X _y ) _z (IV)

However, A in the formula is Y, La, Ce, P
r, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
at least one rare earth element selected from o, Er, Tm, and Yb, M represents at least one metal selected from Ni, Co, and Cu, and X represents B, Al, Ga, and I.
n, Si, Ge, Sn, Pb, Ag, Au, Mg, Z
n, Ru, Pd, Pt, Re, Cs, Ir, Fe, M
at least 1 selected from n, Cr, Cd, Hg, Os
The compound constituting elements of the species are shown, y is 0 ≦ y <1.0, preferably y ≦ 0.5, and z is 0.001 ≦ z ≦ 9.0. A ' _1-x D _x (M _1-y X _y ) _z … (V)

However, A'in the formula is Er, Ho, D
It represents at least one rare earth element selected from y, Tb and Gd, D represents at least one element selected from Pr, Nd, Sm and Ce, and X represents B, Al, Ga and I.
n, Si, Ge, Sn, Pb, Ag, Au, Mg, Z
n, Ru, Pd, Pt, Re, Cs, Ir, Fe, M
at least 1 selected from n, Cr, Cd, Hg, Os
X represents 0 ≦ x <1, y represents 0 ≦ y ≦ 0.3 when X is Fe, and 0 represents X other than Fe.
≦ y <1.0, preferably y ≦ 0.5, z is 0.001
≦ z ≦ 9.0 is shown.

In the above general formulas (IV) and (V),
When the substituted metal X is Fe, y needs to be 0.3 or less. This is because the direct exchange action of Fe-Fe is strong, and if Fe is excessively replaced, the temperature at which the specific heat peak appears becomes as high as 77K or higher. The gas cycle of the refrigerator according to the present invention will be described with reference to FIGS.

In FIG. 3, the heat storage device 1 is filled with the heat storage material 2 described above. One end of the heat storage unit 1 is connected to a working medium source (not shown) through a pipe 3.
The other end of the heat storage unit 1 is connected to the expansion cylinder 4 through a pipe 5. The piston 6 is slidably mounted in the expansion cylinder 3. When the fixer 6 operates, the internal volume of the cylinder 3 is changed. The heat accumulator 1 has four steps (a) to form the following one refrigeration cycle.
It is cooled according to (c).

In step (a), as shown in FIG. 3 (A), the piston 6 is moved in the direction of the arrow 7, thereby increasing the internal volume of the expansion cylinder 4, and at the same time, the high pressure gas is fed from the working medium source by the arrow. It is introduced in the direction of 8. The high-pressure gas passes through the regenerator 1 before flowing into the expansion cylinder 4. When the high-pressure gas passes through the heat storage device 1, the high-pressure gas is cooled by the heat storage material 2.
The cooled gas is accumulated in the expansion cylinder 3.
The arrow 9 indicates the direction in which heat is transferred from the gas to the heat storage material 2 in the heat storage device 1.

In the step (b), as shown in FIG. 3B, a part of the gas is expanded by sucking in a direction of an arrow 10 by a suction means (not shown) connected to the pipe 3 so that a part of the gas is expanded. Is discharged in the direction of the arrow 10 while maintaining the internal volume of the cylinder 4. as a result,
The gas remaining in the cylinder 4 expands, thereby lowering the temperature in the expansion cylinder 4. The cylinder 4
The gas released from is supplied to the heat storage device 1 through the pipe 5. When this gas passes through the heat storage device 1, the gas takes heat from the heat storage material 2. The arrow 11 indicates that the heat is the heat storage device 1.
The direction in which the heat storage material 2 inside is transferred to the gas is shown.

In step (c), the piston 6 is actuated in the direction of arrow 12 as shown in FIG. 3 (C), whereby low temperature, low pressure gas from the expansion cylinder 4 accumulates heat in the direction of arrow 11 through the pipe 5. Discharge into vessel 1. When this gas flows through the heat storage device 1, the gas is stored in the heat storage material 2
Take away the heat. In other words, the gas cools the heat storage material 2. The arrow 13 indicates the direction in which heat is transferred from the heat storage material 2 in the heat storage device 1 to the gas. In the final step (d), the operation is returned to step (a).

[0032]

The heat storage material used in the present invention has the general formula
The rare earth element with high rare earth concentration represented by (I) and Ni,
Since it is composed of one or more selected from magnetic materials having a composition based on a transition metal represented by M such as Co, it is relatively inexpensive and has an excellent thermal conductivity of 10 mW / cmK or more. In addition, it exhibits excellent lattice specific heat and magnetocaloric effect at a liquid nitrogen temperature or lower, particularly at an extremely low temperature of 40 K or lower. In particular, by setting z in the general formula (I) within the range of 0.01 ≦ z <2.0, it is possible to obtain a heat storage material made of a magnetic material having an improved lattice specific heat on the high temperature side.

Since the low temperature heat storage device used in the present invention is filled with the heat storage material composed of the magnetic material having the above-mentioned excellent properties so that the cooling gas can flow therethrough, it has excellent heat transfer properties and recuperative properties. . Especially, the average particle diameter or fiber diameter is 1
By filling the heat storage material made of a magnetic substance of ˜2000 μm, it is possible to obtain uniform heat transfer properties and reduce the pressure loss of the working medium. In addition, the general formula
By filling the heat storage material made of a magnetic material in which z of (I) is in the range of 0.01 ≦ z <2.0, the lattice specific heat on the high temperature side of the heat storage material can be improved, and therefore, a more excellent heat Transfer characteristics and recuperative characteristics can be demonstrated.

Further, the magnetic substance represented by the general formula (I) is
By filling the heat storage material as a mixed aggregate of more than one species, the specific heat peak becomes a blow and the heat capacity decreases, but the specific heat increases in a wider temperature range, so the recuperation characteristics are further improved. It is possible to realize a low temperature heat storage device.

Further, the heat storage material is filled in the form of laminating a plurality of kinds of magnetic materials having different magnetic transition points (the temperature at which the specific heat shows a peak) according to the temperature gradient, whereby the recuperative characteristics are further improved. A low temperature heat storage device can be realized. Therefore,
According to the present invention, since the low temperature heat storage device described above is provided,
It is possible to provide an 8K or 4K class refrigerator with significantly improved cold storage efficiency.

[0036]

EXAMPLES Examples of the present invention will be described in detail below. Examples 1-3

First, using an arc melting furnace, ErNi _1/3
Alloy with composition ratio of Er, alloy with composition ratio of ErNi and ErN
Prepare alloys with the composition ratio of i ₂ respectively, and
After uniformly heat-treated at 00 ° C. for 24 hours, it was pulverized and classified by a brown mill to prepare finely pulverized powder of 100 to 200 μm. Subsequently, 200 g of these finely pulverized powders were plasma-sprayed in an argon gas atmosphere to produce three kinds of magnetic materials. The final argon gas pressure reached by the plasma spray was 1.8 atm. When the obtained magnetic bodies of Examples 1 to 3 were observed by SEM photographs, it was confirmed that they were spherical bodies having an average particle diameter of 40 to 100 μm.

Further, the volume specific heat of each of the obtained spherical magnetic bodies was measured, and the characteristic diagram shown in FIG. 4 was obtained. Note that FIG.
The volume specific heats of Pb and Cu as comparative examples are also shown therein. As is clear from FIG. 4, the spherical magnetic bodies as the heat storage materials of Examples 1 to 3 all have a volume specific heat superior to that of the conventional heat storage materials Pb and Cu at an extremely low temperature of about 15 K or less. It is also found that the lattice specific heat is excellent in the temperature range of 15 K or higher. In particular, alloys having a composition in which z in the general formula (I) is in the range of 0.01 ≦ z <2.0 (Example 1; ErNi _1/3 , Example 2; ErN).
It can be seen that i ₂ ) has an excellent lattice specific heat comparable to Pb in the temperature range of 15 K or higher.

Further, in the spherical magnetic material, ErNi
Spherical magnetic material with _1/3 composition ratio (average particle size 50-100 μm)
Filled in a phenol resin heat storage unit (filling rate: 63%)
After that, helium gas with a heat capacity of 25 J / K was added at 3 g / se
G supplied under the conditions of mass flow rate of c and gas pressure of 16 atm
The M refrigeration cycle was performed to measure the cold storage efficiency. As a result, a refrigerator equipped with a regenerator filled with a spherical magnetic material having a composition ratio of ErNi _1/3 is a refrigerator equipped with a regenerator filled with spherical lead (comparative example) having the same average particle size and filling rate. 4 compared to
It was confirmed that the efficiency was improved eight times or more in the temperature range of 0K to 4K. Examples 4-7

First, using an arc melting furnace, DyNi _1/3
Alloy with composition ratio of Er, alloy with composition ratio of Er _0.5 Dy _0.5 Ni _1/3 , alloy with composition ratio of Er _0.75 Dy _0.25 Ni _1/3 and E
After preparing alloys having the composition ratio of rNi _1/3 , four kinds of magnetic materials were produced from these alloys by the same method as in Example 1. When the obtained magnetic bodies of Examples 4 to 7 were observed by SEM photographs, it was confirmed that they were spherical bodies having an average particle diameter of 40 to 100 μm.

Further, the volume specific heat of each spherical magnetic material was measured, and the characteristic diagram shown in FIG. 5 was obtained. The volume specific heat of Pb as a comparative example is also shown in FIG. This Figure 5
As is clear from the above, the spherical magnetic bodies as the heat storage materials of Examples 4 to 7 all have a volume specific heat superior to that of the conventional heat storage material Pb at an extremely low temperature of about 15 K or less, and 15 K or more. It can be seen that it has an excellent lattice specific heat in the temperature range of. Moreover, it can be seen that in the spherical magnetic bodies of Examples 4 to 7, the temperature showing the peak value of the volume specific heat shifts to the low temperature side as the concentration of Er, which is a component of the alloy, increases. Examples 8-10

First, using an arc melting furnace (Er _0.8 P
r _0.2 ) Ni _1/3 composition ratio alloy, (Er _0.7 P
r _0.3 ) Ni _1/3 alloy and (Er _0.6 Pr)
_0.4 ) Ni _1/3 composition ratio alloys are prepared, respectively,
Three kinds of magnetic materials were produced from these alloys in the same manner as in Example 1. The obtained magnetic materials of Examples 8 to 10 were SE
Observed in the M photograph, the average particle size is 40 to 100 μm.
It was confirmed to be a spherical body.

After filling the spherical magnetic bodies of Examples 1 to 10 into the phenol resin heat accumulators respectively (filling rate: 65%), 3 g / sec of helium gas having a heat capacity of 25 J / K was obtained. A refrigeration test was performed by performing a GM refrigeration cycle in which the gas flow rate was 16 atm and the gas pressure was 16 atm. As a result, in the refrigerator provided with the heat storage device filled with the spherical magnetic bodies of Examples 1 to 10, the refrigerator provided with the heat storage device filled with spherical lead (comparative example) having the same average particle diameter and filling rate was used. By comparison, it was confirmed that the minimum temperature reached in the unloaded state was decreased by 1K or more. Examples 11 and 12

First, using an arc melting furnace, ErCo _1/3
An alloy having the composition ratio of 1 and an alloy having the composition ratio of ErCo were prepared, and subjected to uniform heat treatment at 750 ° C. for 24 hours, and then pulverized and classified by a brown mill to 100 to 2
A finely pulverized powder of 00 μm was prepared. Subsequently, 200 g of these finely pulverized powders were plasma sprayed in an argon gas atmosphere to produce two kinds of magnetic materials. The final argon gas pressure in the plasma spray was 1.8 atm. The obtained Example 11,
As a result of observing the magnetic substance of No. 12 with an SEM photograph, it was confirmed that the magnetic substance was a spherical body having an average particle diameter of 40 to 100 μm.

Further, after filling each of the spherical magnetic bodies into a phenol resin heat storage unit (filling rate: 65%),
The GM refrigeration cycle in which a helium gas having a heat capacity of 25 J / K was supplied at a mass flow rate of 3 g / sec and a gas pressure of 16 atm was performed to measure the cold storage efficiency. As a result, in the refrigerator provided with the heat storage device filled with the spherical magnetic bodies of Examples 11 and 12, the refrigerator provided with the heat storage device filled with spherical lead (comparative example) having the same average particle size and the same filling rate was used. 8 efficiency compared to
It was confirmed to be more than doubled. Examples 13 to 15

First, using an arc melting furnace (Er _0.8 N
d _0.2 ) Co _1/3 alloy composition, (Er _0.7 N
alloy with a composition ratio of d _0.3 ) Co _1/3 and (Er _0.6 Nd
After preparing the alloys with the composition ratio of _0.4 ) Co _1/3 ,
Three kinds of magnetic materials were produced from these alloys in the same manner as in Example 11. When the obtained magnetic materials of Examples 13 to 15 were observed by SEM photographs, the average particle diameter was 40 to 100.
It was confirmed to be a spherical body of μm.

After filling each spherical magnetic material into a phenol resin heat storage unit (filling rate: 65%),
The GM refrigeration cycle in which a helium gas having a heat capacity of 25 J / K was supplied at a mass flow rate of 3 g / sec and a gas pressure of 16 atm was performed to measure the cold storage efficiency. As a result, in the refrigerator provided with the heat storage device filled with the spherical magnetic bodies of Examples 13 to 15, the refrigerator provided with the heat storage device filled with spherical lead (comparative example) having the same average particle diameter and filling rate was used. 8 efficiency compared to
It was confirmed to be more than doubled. Examples 16 and 17

First, an alloy having a composition ratio of ErCu ₂ and an alloy having a composition ratio of ErCu were prepared using an arc melting furnace, and these alloys were subjected to uniform heat treatment at 850 ° C. for 24 hours, and then subjected to a brown mill. Crush and classify with 100 to 20
A 0 μm finely pulverized powder was prepared. Subsequently, 200 g of these finely pulverized powders were plasma sprayed in an argon gas atmosphere to produce two kinds of magnetic materials.
The final argon gas pressure in the plasma spray was 1.8 atm. Obtained Examples 16 and 17
When the magnetic substance of No. 4 was observed with the SEM photograph, the average particle size was 4
It was confirmed to be a spherical body of 0 to 100 μm.

After filling each spherical magnetic material into a phenol resin heat storage unit (filling rate: 65%),
The GM refrigeration cycle in which a helium gas having a heat capacity of 25 J / K was supplied at a mass flow rate of 3 g / sec and a gas pressure of 16 atm was performed to measure the cold storage efficiency. As a result, in the refrigerator provided with the heat storage device filled with the spherical magnetic material of Examples 16 and 17, the refrigerator provided with the heat storage device filled with spherical lead (comparative example) having the same average particle size and filling rate was used. 7 compared to efficiency
It was confirmed to be more than doubled. Examples 18-23

First, using an arc melting furnace, ErNi _1/3
Alloy with a composition ratio of Er, alloy with a composition ratio of ErNi, ErCo
Alloy with composition ratio of _1/3 , alloy with composition ratio of ErCo, ErC
An alloy having a composition ratio of u _1/3 and an alloy having a composition ratio of ErCu were prepared. Subsequently, each of the above alloys was sprayed onto a woven fabric of tungsten (W) fibers having a fiber diameter of 10 μm to manufacture six types of fibrous magnetic bodies. Obtained Examples 18 to 23
The average fiber diameter of the fibrous magnetic substance of
It was confirmed to be 100 μm.

Further, the fibrous magnetic materials were laminated and filled in a phenol resin heat storage unit (filling rate: 75%).
After that, helium gas with a heat capacity of 25 J / K was added at 3 g / se
G supplied under the conditions of mass flow rate of c and gas pressure of 16 atm
The M refrigeration cycle was performed to measure the cold storage efficiency. As a result, in the refrigerator provided with the heat accumulator in which the fibrous magnetic materials of Examples 18 to 23 were laminated and filled, a woven fabric (comparative example) of fibers having the same fiber diameter and filling rate and made of lead alone was filled. It was confirmed that the efficiency was improved 10 times or more as compared with the refrigerator equipped with the heat storage device.

[0052]

As described above in detail, according to the present invention, 10
A heat storage material having excellent thermal conductivity of mW / cmK or more and excellent lattice specific heat and magnetocaloric effect at liquid nitrogen temperature or lower, especially at extremely low temperature of 40K or lower, filled heat transfer characteristic, recovery It is possible to provide an 8K or 4K class refrigerator having a relatively inexpensive low temperature heat storage device having thermal characteristics and having improved cold storage efficiency. In addition, in particular, by making the magnetic material that is the heat storage material into a spherical shape having a predetermined average particle diameter or a fibrous shape having a predetermined fiber diameter, it is possible to regularly fill in the three-dimensional direction, the filling rate, the working medium such as helium gas. It is possible to provide a refrigerator having a low-temperature heat storage device which has further improved heat transfer characteristics with and has achieved reduction in pressure loss.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a spin structure of ErNi.

FIG. 2 is an explanatory diagram showing a spin structure of ErNi _1/3 .

FIG. 3 is a schematic diagram for explaining a gas-cycle of the refrigerator according to the present invention.

FIG. 4 is a characteristic diagram showing the volume specific heat at low temperatures of the spherical magnetic bodies (heat storage materials) of Examples 1 to 3 and the conventional Pb and Cu heat storage materials.

FIG. 5 is a characteristic diagram showing the volume specific heat under low temperature in the spherical magnetic bodies (heat storage materials) of Examples 4 to 7 and the conventional Pb heat storage material.

[Explanation of symbols]

1 ... Heat storage device, 2 ... Heat storage material, 4 ... Expansion cylinder, 5 ... Piston.

Claims (2)

[Claims] 1. A refrigerator provided with a low temperature heat storage device filled with a heat storage material so that a cooling gas can flow therethrough, wherein the heat storage material is represented by the general formula (I) AM _z ... (I) (wherein A is Y, La, Ce, Pr, Nd, P
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
represents at least one rare earth element selected from m and Yb, and M represents at least 1 selected from Ni, Co and Cu.
(Indicates a metal of a kind, z is 0.001 ≦ z ≦ 9.0)
Represented by an average particle size Ri Do from one or more members selected from the granular magnetic material 1～2000Myuemu, and the temperature is
A refrigerator having a specific heat peak below 77K . 2. A refrigerator provided with a low temperature heat storage device filled with a heat storage material so that a cooling gas can flow therethrough, wherein the heat storage material is represented by the general formula (I) AM _z ... (I) (wherein A is Y, La, Ce, Pr, Nd, P
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
represents at least one rare earth element selected from m and Yb, and M represents at least 1 selected from Ni, Co and Cu.
(Indicates a metal of a kind, z is 0.001 ≦ z ≦ 9.0)
Expressed by the average diameter Ri Do from one or more selected from fibrous magnetic material 1～2000Myuemu, and the temperature is
A refrigerator having a specific heat peak below 77K .