JP2003060244A - Cooling element and thermoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling element capable of improving conversion effi ciency from electricity to heat of an thermoelectric conversion element by using multiplier effect of peltier effect and Ettingshausen effect. SOLUTION: A set of rectangular solid is formed with p-type and n-type strip thin-sheet thermoelectric conversion elements 1, having the ratio 5 or more of (length of long side (z-direction)/length of short side (x-direction)) contacted against each other and alternately laminated in (n) sheets, and a rectangular element is composed by alternately laminating the rectangular solids and rectangular solid permanent magnets 2. Electrodes 3 and 4 are formed on one high temperature side and the other cold temperature side of a pair of opposed sides formed by y-axis and z-axis on each material. Each of the permanent magnets 2 is magnetized in the laminated direction (y) of the thin conversion elements 1 to generate magnetic field B in the same direction. Each of the terminals 3, 4 is connected to feed current in the widthwise direction (x) of the elements 1 orthogonal to the direction of the magnetic field B. Then, current I is applied to the terminals 3, 4 to generate temperature gradient in the longitudinal direction (z) of the elements 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling element in which a thermoelectric conversion element having a specific shape is used and a magnetic field is applied to the thermoelectric conversion element to improve the efficiency of conversion of electric energy into heat energy.

[0002]

2. Description of the Related Art Peltier devices are used in order to prevent heat storage that occurs when electronic devices are made smaller and more compact.
Devices that are expected to improve the efficiency of conversion from electricity to cold heat, such as temperature control of semiconductor laser oscillators for optical communication, temperature control of reaction tanks in the manufacturing process of semiconductor parts, cold storage, etc. It is used for parts and devices that require precise temperature control.

Thermoelectric conversion materials for Peltier devices include:
In addition to chalcogen compounds having high performance such as IrSb ₃ , Bi ₂ Te ₃ and PbTe, silicides such as FeSi ₂ and SiGe which have low thermoelectric properties but are rich in resources are known.

The Peltier element generates heat (cold heat) by passing an electric current through the thermoelectric conversion material. The conversion efficiency of the Peltier element is the material performance index (ZT = S ² / ρκ, where S is the Seebeck coefficient). , Ρ is proportional to electrical resistivity, and κ is proportional to thermal conductivity. The above thermoelectric conversion material has a high figure of merit of around 1, which is not sufficient.

The energy conversion efficiency of the Peltier device for converting electric energy into heat energy is at most several percent even for Bi ₂ Te ₃ having the highest efficiency, which is much lower than that of solar cells (about 20%). For example, in a semiconductor laser oscillator for optical communication, 80% of the energy consumed by the oscillator is used for cooling, and this low efficiency is the main reason for narrowing the application of the Peltier device.

[0006]

It is known as an Etchingshausen effect that the cooling efficiency is improved by applying a magnetic field to the thermoelectric conversion material in which an electric current is passed (LL Campbell,
"Galvanomagnetic and ther
momographic Effects ”, (Lon
don: Longmans, Green), cha
p. 9 (1923)).

In addition, an etching Shausen element that applies a magnetic field to convert electricity into heat or vice versa,
For example, it is disclosed in JP-A-63-257282. In FIG. 7, the etching-Shausen element 11 is sandwiched between magnets 12 having N and S poles facing each other, and this is installed on an insulating base 13.

As shown in FIG. 7, the etching Schauzen effect means that when a current I is passed through an etching Schauzen element in the x-axis direction and a magnetic field B is applied in the y-axis direction perpendicular to the direction, the z-axis is applied. A temperature gradient ∇T is generated in the direction.

What is further improved from the structure disclosed in Japanese Patent Laid-Open No. 63-257282 is Japanese Patent Laid-Open No. 4-2068.
No. 84 publication. As shown in FIG. 8, the etching Schausen element thin film 21 is formed on the electrically insulating substrate 23.
And magnetized magnetic thin films 22 are alternately formed in a strip shape, and they are connected in series by an Al thin film 24, and each is formed in a direction (x-axis direction) perpendicular to the magnetic field direction (y-axis direction) generated by the magnetic thin film 22. The thermoelectric devices are arranged and connected so that currents flow in the same direction.

The structure described in the above-mentioned Japanese Patent Laid-Open No. 4-206884 can obtain effects such that the device can be downsized, cooling can be performed in a plane, and mass production is possible. However, the energy conversion efficiency is still low, and it has not reached the high efficiency in recent years.

On the other hand, O'Brinen and Wallac
e is Peltier material exponential cyli
It was clarified that the cooling efficiency was improved when it had a special shape called nder, and it was shown that the cooling efficiency depends on the shape of the thermoelectric material (BJ O'Brien a.
nd C.I. S. Wallace, J.M. App
l. Phys. 29 (1958) 1010). Further, Ertl et al. Increase the conversion efficiency from electricity to heat when a current is passed in the x-axis direction of a rectangular parallelepiped thermoelectric conversion material, a magnetic field is applied in the y-axis direction, and the z-axis is the direction of the generated temperature gradient. In order to achieve this, it is pointed out that the optimum aspect ratio (ratio of x-axis length and z-axis length) for the thermoelectric conversion material is required (ME Ertl, GR Pfi).
star H. J. Goldsmid, B
r. J. Appl. Phys. 14 (196
3) 161).

However, these experiments are all results at low temperature, and the cooling efficiency of the device utilizing the etching-Shausen effect at room temperature was extremely low.

An object of the present invention is to provide a cooling element capable of improving the efficiency of conversion of electricity of a thermoelectric conversion material into heat by utilizing the synergistic effect of the Peltier effect and the etching Shausen effect.

[0014]

Means for Solving the Problems In view of the fact that the improvement of the cooling efficiency is limited only by improving the characteristics of the thermoelectric conversion material, the inventor has conducted earnest research on the optimum shape of the thermoelectric conversion material, and as a result, X is the direction of current flow in the material
A shape in which (axis length, length of z-axis / length of x-axis) is 5 or more and y-axis length is 1 mm or less, where y is the axis, the direction of the magnetic field and z is the direction of the temperature gradient. It was found that the cooling efficiency is remarkably improved by the above.

Further, the inventor has made a plurality of thermoelectric conversion materials of the above-mentioned shape one set and arranged them alternately with the permanent magnets, and optimized the position of the electrode for passing the current I and the wiring method. It was found that the cooling efficiency is further improved by this, and the present invention has been completed.

That is, the present invention provides the following (1) to (1
This is achieved by either configuration of 2).

(1) When the x-axis is the direction in which the current I flows, the y-axis is the direction of the magnetic field B, and the z-axis is the direction of the temperature gradient ▽ T,
A cooling element using a thermoelectric conversion material having a (length of z-axis / length of x-axis) of 5 or more and a length of y-axis of 1 mm or less, which is in the y-axis direction of the thermoelectric conversion material. It has a permanent magnet for applying a magnetic field B, and y of the thermoelectric conversion material.
A cooling element having electrodes on each of a pair of opposing surfaces formed by an axis and a z-axis, and causing a current I to flow through the electrodes to generate a temperature gradient ▽ T in the z-axis direction.

(2) The cooling element according to (1), wherein the magnitude of the magnetic field B is 0.1 T or more.

(3) A plurality of thermoelectric conversion materials and permanent magnets are alternately arranged in the y-axis direction of the thermoelectric conversion material, (1).
The cooling element according to 1.

(4) The cooling element according to (3) above, wherein a plurality of thermoelectric conversion materials form one set.

(5) One set of cooling elements in which a plurality of thermoelectric conversion materials and permanent magnets are alternately arranged in the y-axis direction of the thermoelectric conversion material is set, and both ends of each of the plurality of sets of cooling elements are made of a magnetic material. The cooling element according to (3) above, which is connected to form a closed magnetic circuit circuit.

(6) The thermoelectric conversion material is of p-type and n-type, and one of a pair of opposing surfaces formed by the y-axis and the z-axis of each material has a high temperature side on one side and a low temperature side on the other side. The cooling element according to the above (1), in which an electrode is provided for each of the electrodes, the adjacent electrode of each material on the same temperature side is connected, and each material is connected in series.

(7) The thermoelectric conversion material is p-type or n-type, and one of the pair of facing surfaces formed by the y-axis and the z-axis of each material has a high temperature side on one side and a low temperature side on the other side. The cooling element according to (1) above, in which the electrode is disposed, the electrode and the adjacent electrode on the different temperature side of each material are connected, and each material is connected in series.

(8) The thermoelectric conversion material is p-type or n-type, and one of the pair of facing surfaces formed by the y-axis and the z-axis of each material has a high temperature side on one side and a low temperature side on the other side. The cooling element according to (1) above, in which the electrode is disposed, the electrode is connected to an electrode on the same temperature side of each material adjacent to each other, and each material is connected in parallel.

(9) The cooling element according to the above (1), wherein the thermoelectric conversion material and / or the permanent magnet has an insulating coating on the surface thereof.

(10) The cooling element according to (9) above, wherein the insulating coating is a polyimide coating or an alumina coating.

(11) When the direction of the current I flows is the x-axis, the direction of the magnetic field B is the y-axis, and the direction of the temperature gradient ▽ T is the z-axis, (the length of the z-axis / the length of the x-axis) is A cooling element using a thermoelectric conversion material having a length of 5 or more and a y-axis length of 1 mm or less, a means for applying a magnetic field B in the y-axis direction of the thermoelectric conversion material, and a y-axis of the thermoelectric conversion material. And a means for passing a current I between a pair of opposing surfaces formed by the z axis, and a cooling element for generating a temperature gradient ∇T in the z axis direction.

(12) When the x-axis is the direction in which the current I flows, the y-axis is the direction of the magnetic field B, and the z-axis is the direction of the temperature gradient ∇T, (z-axis length / x-axis length) is A thermoelectric conversion material for a cooling element having a length of 5 or more and a y-axis length of 1 mm or less.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The principle and structure of a cooling element for converting electricity into heat according to the present invention will be described below.
A current I is applied in the direction from the lower front side to the upper side (x-axis direction) in the drawing (the x-axis direction) to the rectangular parallelepiped thermoelectric conversion material 1 having the height a, width b, and thickness d / n shown in FIG. If a magnetic field B is applied in the direction, the temperature difference ΔT (T ₁ −
T ₂ ) occurs.

The ΔT of the Peltier effect and the ΔT of the etching Shausen effect are individually theoretically described in B. J.
O'Brien and C.I. S. Walla
Although it is given by ce, there has been no result of analyzing collectively. The following expressions (1) and (2) collectively represent ΔT due to the Peltier effect and the etching Shausen effect in one expression.

[0031]

[Equation 1]

I-Ix + Iz (2)

Here, the first term is the temperature difference due to the etching-Shausen effect, and the second term is the temperature difference due to the Peltier effect. Pe is the etching Shausen coefficient, P
Is Peltier coefficient, κ is thermal conductivity, ρ is electrical resistivity, Ix
And Iz represent the magnitude of the current in the x-axis and z-axis directions, respectively. If equation (3) is used for simplification, the components Ix and Iz of the current I can be approximately represented by equation (4).

B / a = X (3)

[0035] Ix = I · x / (1 + x), Iz = I / (1 + x) (4)

Substituting equations (3) and (4) into equation (1), equation (1) becomes equation (5).

[0037]

[Equation 2]

Next, X and n that maximize the temperature difference of the equation (5) are calculated by the equation (6). Then, the formula (7) is obtained from the formula (6), and the formula (9) is obtained from the formula (8).

[0039]

[Equation 3]

[0040]

[Equation 4]

[0041]

[Equation 5]

[0042]

[Equation 6]

By substituting the equation (9) into the equation (7), the equation (7) is strictly obtained and becomes the equation (10).

[0044]

[Equation 7]

In order to maximize the temperature difference ΔT,
It indicates that the aspect ratio (= b / a) of the thermoelectric conversion material must be changed depending on the magnitude of the magnetic field B.

Next, substituting equation (10) into equation (9) yields equation (11), and equations (10) and (11) are transformed into equation (5).
Substituting into, equation (5) becomes equation (12).

[0047] n = dPX (1 + X) / ρI Equation (11)

[0048]

[Equation 8]

Here, assuming that the magnetic field B and the current I are values obtained from the equations (10) and (11) using the physical property value of the thermoelectric conversion material and the aspect ratio (= X), the magnetic field is B =
0, that is, when X = 0, the temperature difference is only Peltier effect and ΔT = P ² / 2ρκ, and when X >> 1, Δ
Since T is dramatically improved by the etching-Shausen effect, if the Peltier effect is ignored, ΔT = κ (PeB)
It becomes ² / 2ρ. This result is consistent with the result of individually obtaining the temperature difference caused by the Peltier effect and the etching Shausen effect.

Next, n will be examined. ΔT in equation (12)
Is the optimum thickness t when the thickness d of the thermoelectric conversion material is divided into n equal parts.
It is a temperature difference with respect to (d / n), that is, the thickness t of each thermoelectric conversion material is expressed by Expression (11) to Expression (13).

[0051] t = d / n = ρI / PX (1 + X) (13)

Here, since ρ and P are physical property values of the thermoelectric conversion material and X is a geometrical value of the material, the thickness t of the material is closely related to the current value. I understand. It can be seen that in order to reduce the current value as much as possible and increase the temperature difference of the thermoelectric conversion materials as much as possible, the thickness of each thermoelectric conversion material should be thin.

That is, if a thermoelectric conversion material having a thickness of d is used instead of a thermoelectric conversion material having a thickness of d, the same effect can be obtained at a current of I / n. Until now, in order to increase the cooling efficiency of the element using the Peltier effect and the etching Shausen effect,
The importance of the aspect ratio of the thermoelectric conversion material was pointed out, but its thickness was not mentioned at all.

In order to apply the above analytical formula to, for example, a thermoelectric conversion material made of polycrystalline Bi, ρ = 1.2 × 10 ⁻⁶ (Ωm), Pe as a physical property value of the thermoelectric conversion material at room temperature.
= 2.3 × 10 ⁻³ (m ³ K / Ws), κ = 7.9 (W /
mK), P = 3 × 10 ⁻² (V), and B = 1.2 (Vs / m ² ) and I = 3 (A) as the magnetic field and current, the equation (10) is obtained. X becomes X = 0.85,
Further, t in the equation (13) is t = 0.076 (mm).
Substituting these values into equation (12), ΔT = 72.6
(K) is obtained.

This is the thickness t = 0.076 (m
This is a temperature difference between both ends obtained when the polycrystalline Bi material of m) is used, and is an ideal state in which there is no heat dissipation or heat absorption by the atmosphere. However, in reality, it is difficult to form such a thin plate of Bi (in terms of strength), and it is difficult to achieve such a temperature difference due to the influence of the heat input and output between the thermoelectric conversion material and the surrounding environment.

From the above analysis results, if n thermoelectric conversion materials having a thickness t are stacked and the total thickness is d, the temperature difference ΔT of the thermoelectric conversion material at the current value of I / n is the thickness d of the thermoelectric material. It is the same as when the current I is passed. Therefore, the thermoelectric conversion material should be made as thin as possible and placed in multiple layers in an electrically insulated state, and the electrodes provided on the high temperature side and low temperature side of each thermoelectric conversion material should be connected by lead wires to generate heat from the electrical energy. The conversion efficiency to energy can be improved.

The characteristics of the present invention are based on the above analysis results.
Further, the cooling element is configured by using a thermoelectric conversion material whose shape and dimension are optimized for application to an actual thermoelectric conversion material. That is, when the direction of the current I flows is the x-axis, the direction of the magnetic field B is the y-axis, and the direction of the temperature gradient ▽ T is the z-axis, (the length of the z-axis / the length of the x-axis) is 5 or more. And using a thermoelectric conversion material having a y-axis length of 1 mm or less,
Means for applying a magnetic field B in the y-axis direction of the thermoelectric conversion material;
The thermoelectric conversion material has a means for causing a current I to flow between a pair of opposing surfaces formed by the y axis and the z axis, and has a temperature gradient ▽ in the z axis direction.
It is a cooling element that generates T.

As a more specific structure, a permanent magnet for applying a magnetic field B is arranged in the y-axis direction of the thermoelectric conversion material, and a pair of opposed electrodes formed by the y-axis and the z-axis of the thermoelectric conversion material are arranged. It is a cooling element which has electrodes on each of the surfaces and generates a temperature gradient ∇T in the z-axis direction by passing a current I through the electrodes.

When the (z-axis length / x-axis length) of the thermoelectric conversion material is less than 5, or when the y-axis length exceeds 1 mm, a predetermined magnetic field and current are applied to the thermoelectric conversion material. The synergistic effect of the Peltier effect and the etching Shausen effect obtained when applied is reduced, and the cooling efficiency is significantly reduced. Therefore, the length (z-axis length / x-axis length) of the thermoelectric conversion material is 5 or more, and the y-axis length is 1 mm or less.

As means for applying the magnetic field B, it is possible to use a known magnetic field generator such as an electromagnetic coil or a superconducting magnet in addition to using a permanent magnet, but to downsize the device,
It is particularly preferable to use a permanent magnet in terms of weight saving and maintenance.

For example, when a Sm-Co type or Nd-Fe-B type rare earth permanent magnet is used as the permanent magnet, it is very convenient for practical use as a cooling element. 55
When cooling is performed at a high temperature of 0 K or higher, a Sm-Co-based permanent magnet (Tc = 1170 K) having a high Curie point is preferable, and when it is less than 550 K, an Nd-Fe-B-based permanent magnet is preferable.

The magnitude of the magnetic field B is preferably 0.1 T or more, and the synergistic effect described above effectively functions. A more preferable magnetic field is 0.3 T or more. That is, when the magnetic field B is reduced, a large temperature difference cannot be obtained because the generated temperature difference is almost the Peltier effect. Further, when the current value is lowered, the Peltier effect and the etching Shausen effect are reduced, and a large temperature difference cannot be obtained. Therefore, by applying a predetermined magnetic field and current to the thermoelectric material, the temperature difference between the thermoelectric conversion materials is dramatically increased by the synergistic effect of the Peltier effect and the etching Schauzen effect, and the cooling efficiency is significantly improved.

In the present invention, as the thermoelectric conversion material, known materials such as chalcogen compounds such as IrSb ₃ , Bi ₂ Te ₃ and PbTe and silicides such as FeSi ₂ and SiGe can be used. A Bi-based material having a high degree is particularly preferable. By using the Bi-based material, the synergistic effect of the Peltier effect and the etching Schauzen effect can be more exerted, and the conversion efficiency can be increased.

When a Bi-based single crystal material is used as the thermoelectric conversion material, an electric current is passed in the C-axis direction to generate a bisect.
It is preferable that the magnetic field is applied in the direction of the rix axis and the temperature difference is generated in the direction of the binary axis. If the thickness in the biaxial axis direction is reduced with such a configuration, a module with low current and high cooling efficiency can be obtained.

When the Bi-based material is used, the electric resistivity of the material is as low as 10 ⁻⁶ (Ωm) order.
Even if the thickness of the thermoelectric conversion material in the y-axis direction is made thin, there is an advantage that a large current can be obtained at a low voltage, and since the material has a semimetal, it has the same number of electrons and holes and has a carrier mobility. Since it is large, a relatively large etching Shausen effect can be obtained even in a low magnetic field, so that a module with a low magnetic field, low current and high cooling efficiency can be obtained.

In the present invention, the thermoelectric conversion material is preferably arranged alternately with the permanent magnets along the y-axis direction of the thermoelectric conversion material. In particular, as shown in FIG. 2, by alternately arranging a plurality of thermoelectric conversion materials 1 and permanent magnets 2 as a set, the conversion efficiency from electric energy to heat energy can be further improved.

The electrodes for passing a current I through the thermoelectric conversion material are respectively a high temperature side of one surface and a low temperature side of the other surface in a pair of opposing surfaces formed by the y axis and the z axis of the thermoelectric conversion material. It is preferable to be arranged at. By adopting this arrangement, the conversion efficiency can be further improved.

The material used for the electrodes and the lead wire for connecting the electrodes are basically made of any material,
Although it can be used even if it has a form, in the case of a thermoelectric conversion material having a low melting point (less than 600 K), it is preferable to use a low melting point material (for example, In solder) as an electrode material. In the case of a thermoelectric conversion material having a high melting point, it is not necessary to limit the electrode material.

The thermoelectric conversion material shown in FIG. 2 is a strip thin plate (y-direction thickness t, 1 mm or less) having a ratio of the long side (z direction) to the short side (x direction) of 5 or more. , P
Molds and n-types are alternately brought into contact with each other at their principal surfaces and n sheets are laminated to form a set of rectangular parallelepiped (lamination thickness d = n · t) thermoelectric conversion material. This set of thermoelectric conversion materials is used as a permanent magnet 2
And a plurality of them are arranged alternately. Each of the permanent magnets 2 is magnetized in the lamination (y) direction of the thin plate-shaped thermoelectric conversion material 1 to generate a magnetic field B in the same (y) direction.

In each thermoelectric conversion material 1, electrodes 3 and 4 are formed in advance on the high temperature side of one surface and the low temperature side of the other surface of a pair of opposing surfaces formed by the y axis and the z axis. .
An element is completed by connecting each electrode so that a current flows in the direction of the short side width (x) of each strip-shaped material 1 which is orthogonal to the direction of the magnetic field B of each permanent magnet 2 and completes the element. By applying the current I, a temperature gradient ∇T can be generated in the longitudinal (z) direction of each of the strip thin plate-shaped materials.
The method of connecting each thermoelectric conversion material will be described below.

Taking the four thermoelectric conversion materials located on the left side of FIG. 2 as an example, the leftmost electrode 3 and the left side of the p-type material on the leftmost side of the four thermoelectric conversion materials and the electrode 3 on the left side To the electrode 3 on the lower side (high temperature side) of the second n-type material from the bottom, and on the front side (low temperature side) of the second n-type material from the left
Connect the electrode 4 of No. 3 and the electrode 4 on the upper front side (low temperature side) of the third p-type material from the left, and connect the electrodes on the same temperature side of adjacent materials to each other. Connect in series.

On the other hand, when the thermoelectric conversion material 1 is of p-type only or n-type only, as shown in FIG. Side) electrode 3 and the electrode 4 on the front side (low temperature side) of the second material from the left, and the electrode 3 on the lower side (high temperature side) of the second n-type material from the left and the left side. By connecting to the electrode 4 on the front side (low temperature side) of the third material from, the electrodes on the different temperature sides of adjacent materials are connected,
Connect each material in series. However, this connection method has a problem that the lead wire 5 must be long.

Therefore, as shown in FIG. 4, all the four electrodes 4 on the front side (low temperature side) of the front surface of the thermoelectric conversion material are connected, and all the electrodes 3 on the lower side (high temperature side) of the back surface are connected. As is the case, it is possible to connect them in parallel. In this connection method, although the input voltage must be higher than that in the above configuration, the lead wire 5 can be connected without traversing the permanent magnet or the thermoelectric conversion material, so that the structure is simple and more practical. is there.

When the thermoelectric conversion material and the permanent magnet are alternately arranged, or when a plurality of sets of the thermoelectric conversion material and the permanent magnet are alternately arranged, the thermoelectric conversion material and the permanent magnet (especially rare earth magnet) are Since both exhibit metallic electric conductivity, it is preferable to electrically insulate the thermoelectric conversion materials from each other and the thermoelectric conversion material from the permanent magnet.

The insulating coating is preferably a polyimide coating or an alumina coating having high electric insulation.
A coating thickness of several μm or less is sufficient. By reducing the thickness of the coating, the gap between the magnets can be made close to the total thickness d of the thermoelectric conversion material even if a plurality of thermoelectric conversion materials are inserted into the permanent magnet, and the magnetic flux is reduced as much as possible. Can be suppressed.

The polyimide coating and the alumina coating are appropriately selected depending on the operating temperature. Any coating may be used as long as the operating temperature is 700K or lower, and an alumina coating is suitable when the operating temperature exceeds 700K. It should be noted that when coating the thermoelectric conversion material, it is advisable to perform a masking process in advance on the portion to be the electrode so that the insulating coating does not adhere.

FIG. 5 shows the configuration of a closed magnetic circuit that uses the cooling elements having the various configurations described above. One set of cooling elements in which a plurality of thermoelectric conversion materials 1 and permanent magnets 2 are alternately arranged in the y-axis direction of the thermoelectric conversion material 1 is prepared, and another set of the same configuration is prepared, and they are arranged in parallel. Permanent magnets 2 at both ends of each set
A closed magnetic circuit circuit can be formed by connecting the magnetic material plates 6 such as iron to each other.

FIG. 6 shows an example of a cooling element having a closed magnetic circuit as described above. As shown in the figure, the thermoelectric conversion material 1 is longer than the permanent magnet 2 in the direction of the temperature gradient and is directly attached to the cooling plate 7 or the heat radiating plate 8. It is desirable to design such that there is no heat conduction through the permanent magnet 2 so that they are in contact with each other.

By adopting these configurations, it is possible to automatically give a temperature difference between the upper end and the lower end of the thermoelectric conversion material by passing an electric current through each thermoelectric conversion material.

[0080]

Example In order to confirm the synergistic effect of the Peltier effect and the etching Shausen effect, p-type and n-type Bi-based thermoelectric conversion materials were produced as thermoelectric conversion materials. First, high purity Bi (4N) was mixed with the elements shown in Table 1 in a predetermined ratio, and then vacuum filled in a quartz tube to perform high frequency melting. The obtained cylindrical ingot is 10 × 10 × 1 mm
The hole coefficient was measured to confirm the polarity and carrier concentration. The results are shown in Table 1.

Further, the ingot was cut into the processing dimensions and shapes shown in Table 2, the magnetic field and the current applied to the thermoelectric conversion material were changed, and the temperature difference between the high temperature portion and the low temperature portion was measured 10 seconds after the application. Table 2 shows the magnetic field, current value, and temperature difference. The processing dimensions are based on the definition shown in FIG. In Table 2, the numbers 6, 7, 8, 10, and 12 are the present examples, and the others are comparative examples.

[0082]

[Table 1]

[0083]

[Table 2]

[0084]

According to the present invention, it is possible to utilize the synergistic effect of the Peltier effect and the etching Shausen effect, and it is possible to provide a cooling element with dramatically improved cooling efficiency.

In the present invention, if a permanent magnet is used as the means for applying the magnetic field B, the cooling element can be easily manufactured with a relatively simple structure, and the cooling element can be made smaller and lighter. It has the advantage of being maintenance-free even when used. Furthermore, when a Bi-based material is used as the thermoelectric conversion material, it is possible to provide a cooling element having high cooling efficiency even in a low magnetic field and low current.

[Brief description of drawings]

FIG. 1 is a perspective explanatory view for explaining the principle of a thermoelectric conversion material according to the present invention.

FIG. 2 is a perspective explanatory view showing a configuration example of a thermoelectric conversion element according to the present invention.

FIG. 3 is a perspective explanatory view showing another configuration example of the thermoelectric conversion element according to the present invention.

FIG. 4 is a perspective explanatory view showing another configuration example of the thermoelectric conversion element according to the present invention.

FIG. 5 is an explanatory plan view showing another configuration example of the thermoelectric conversion element according to the present invention.

FIG. 6 is an explanatory plan view showing another configuration example of the thermoelectric conversion element according to the present invention.

FIG. 7 is a perspective explanatory view showing a conventional example.

FIG. 8 is a perspective explanatory view showing a conventional example.

[Explanation of symbols]

1 Thermoelectric conversion material 2 permanent magnet 3, 4 electrodes 5 lead wires 6 Magnetic material plate 7 Cooling plate 8 heat sink 11 Etching Shausen element 12 magnets 13 Insulation stand 21 Etching Shausen element thin film 22 Magnetic thin film 23 Electrically insulating substrate 24 Al thin film

Claims (12)

[Claims] 1. When the direction of current I is x-axis, the direction of magnetic field B is y-axis, and the direction of temperature gradient ▽ T is z-axis, (length of z-axis / length of x-axis) is 5. The above is a cooling element using a thermoelectric conversion material having a y-axis length of 1 mm or less, having a permanent magnet for applying a magnetic field B in the y-axis direction of the thermoelectric conversion material, and performing thermoelectric conversion. Material y-axis and z
A cooling element having an electrode on each of a pair of facing surfaces formed by an axis and generating a temperature gradient ▽ T in the z-axis direction by passing a current I through the electrodes. 2. The cooling element according to claim 1, wherein the magnitude of the magnetic field B is 0.1 T or more. 3. The cooling element according to claim 1, wherein a plurality of thermoelectric conversion materials and permanent magnets are alternately arranged in the y-axis direction of the thermoelectric conversion material. 4. The cooling element according to claim 3, wherein a plurality of thermoelectric conversion materials form a set. 5. A set of cooling elements in which a plurality of thermoelectric conversion materials and permanent magnets are alternately arranged in the y-axis direction of the thermoelectric conversion material is set, and both ends of each of the plurality of sets of cooling elements are made of a magnetic material. The cooling element according to claim 3, wherein the cooling element is connected to form a closed magnetic circuit. 6. The thermoelectric conversion material comprises p-type and n-type,
Electrodes are arranged on the high temperature side of one surface and the low temperature side of the other surface of a pair of opposing surfaces formed by the y axis and the z axis of each material, and the same temperature side of each material adjacent to the electrode. The cooling element according to claim 1, wherein the cooling element and the electrode are connected and the respective materials are connected in series. 7. The thermoelectric conversion material is of p-type or n-type and is provided on each of a high temperature side of one surface and a low temperature side of the other surface of a pair of opposing surfaces formed by the y axis and z axis of each material. The cooling element according to claim 1, wherein an electrode is provided, the electrode and an electrode on a different temperature side of each material adjacent to each other are connected, and each material is connected in series. 8. The thermoelectric conversion material is of p-type or n-type and is provided on each of the high temperature side of one surface and the low temperature side of the other surface of a pair of opposing surfaces formed by the y axis and z axis of each material. The cooling element according to claim 1, wherein an electrode is provided, the electrode is connected to an electrode on the same temperature side of each material adjacent to each other, and each material is connected in parallel. 9. The cooling element according to claim 1, wherein the thermoelectric conversion material and / or the permanent magnet has an insulating coating on the surface thereof. 10. The cooling element according to claim 9, wherein the insulating coating is a polyimide coating or an alumina coating. 11. When the direction in which the current I flows is the x-axis, the direction of the magnetic field B is the y-axis, and the direction of the temperature gradient ▽ T is the z-axis, (z
A cooling element using a thermoelectric conversion material having an axial length / x-axis length of 5 or more and a y-axis length of 1 mm or less, wherein a magnetic field B in the y-axis direction of the thermoelectric conversion material is used. A cooling element that has a means for applying a current and a means for causing a current I to flow between a pair of opposing surfaces of the thermoelectric conversion material formed by the y-axis and the z-axis, and generates a temperature gradient ▽ T in the z-axis direction. 12. When the direction in which the current I flows is the x-axis, the direction of the magnetic field B is the y-axis, and the direction of the temperature gradient ∇T is the z-axis, (z
A thermoelectric conversion material for a cooling element, wherein the length of the axis / the length of the x axis is 5 or more and the length of the y axis is 1 mm or less.