JP2004311819A - Thermoelectric conversion module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric conversion module capable of preventing the generation of distortion in a thermoelectric conversion material even when a temperature gradient is formed and having high durability. <P>SOLUTION: The thermoelectric module 1 for converting a temperature gradient generated between a pair of heat transfer plates 11, 12 opposed to each other into electric energy is provided with a plurality of thermoelectric conversion materials 13 arranged between these heat transfer plates 11, 12, so that respective thermoelectric conversion materials 13 are extended from one heat transfer plate 11 to the other heat transfer plate 12. Both the end faces 131, 132 of two adjacent thermoelectric conversion materials 13 which are respectively turned to the different heat transfer plates 11, 12 are mutually connected through an electrode 17 consisting of a metal or alloy which is different from the thermoelectric conversion materials 13. Since the thermoelectric conversion module 1 can be constituted of one sort of thermoelectric conversion materials 13, the thermoelectric conversion module capable of reducing the generation of distortion or the like due to a thermal expansion difference which may be generated by the mixture of different sorts of materials and having high durability can be obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermoelectric conversion module that converts a temperature gradient generated between a pair of heat transfer plates disposed opposite to each other into electric energy.
[0002]
[Background Art]
BACKGROUND ART Conventionally, as a thermoelectric conversion element utilizing the Seebeck effect, a combination of a p-type thermoelectric conversion material and an n-type thermoelectric conversion material is known (for example, see Patent Document 1).
In this thermoelectric conversion element, as shown in FIG. 2, a columnar or prismatic p-type thermoelectric conversion material 101 and an n-type thermoelectric conversion material 102 are arranged, and one end face of the thermoelectric conversion materials 101 and 102 is disposed between them. It is configured as a so-called π-shaped thermoelectric conversion element in which the metal segments 103 are connected to each other and the metal segments 104 and 105 are connected to the other end faces, respectively.
[0003]
When a temperature gradient is provided between the metal segment 103 and the metal segments 104 and 105, the Seebeck effect based on the joining of the p-type thermoelectric conversion material 101 and the n-type thermoelectric conversion material 102 causes the metal segment 104 and the metal segment 105 to have a temperature gradient. When a current is generated and the motor 106 is connected between them, the motor 106 is driven by the thermoelectromotive force generated by the generated current. When a larger thermoelectromotive force is generated by using such a thermoelectric conversion element, the plurality of thermoelectric conversion elements are electrically connected between the metal segments 104 and 105 so that the p-type thermoelectric conversion materials 101 and n A thermoelectric conversion module in which the thermoelectric conversion materials 102 are connected alternately may be manufactured.
[0004]
[Patent Document 1]
JP-A-11-220184 (see paragraph [0022], FIG. 1)
[0005]
[Problems to be solved by the invention]
However, the thermoelectric conversion element having the conventional structure disclosed in Patent Document 1 has a configuration in which different types of thermoelectric conversion materials are alternately arranged. Therefore, if a temperature gradient is provided between the metal segment 103 and the metal segments 104 and 105, There is a problem that the thermoelectric conversion element may be distorted due to a difference in thermal expansion of each thermoelectric conversion material, and in some cases, the thermoelectric conversion element may be broken.
It is also conceivable to adjust the materials so that the thermal characteristics of the p-type thermoelectric conversion material and the n-type thermoelectric conversion material are matched. However, it is practically difficult, and in particular, oxide-based thermoelectric conversion materials which have been actively developed in recent years are particularly difficult. Then, it is very difficult to control and form p-type and n-type from the same material.
[0006]
An object of the present invention is to provide a thermoelectric conversion module that does not cause distortion in a thermoelectric conversion material even when a temperature gradient is provided and has good durability.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a thermoelectric conversion module of the present invention is a thermoelectric conversion module that converts a temperature gradient generated between a pair of opposed heat transfer plates into electric energy, wherein the thermoelectric conversion module is provided between the pair of heat transfer plates. And two or more thermoelectric conversion materials each extending from one heat transfer plate toward the other heat transfer plate, and facing two different heat transfer plates of two thermoelectric conversion materials adjacent to each other. The end faces are connected by an electrode made of a metal or an alloy different from the thermoelectric conversion material.
Here, the above-mentioned thermoelectric conversion material is preferably an oxide-based thermoelectric conversion material.
[0008]
As the thermoelectric conversion material, either a p-type thermoelectric conversion material or an n-type thermoelectric conversion material can be adopted. As the p-type oxide-based thermoelectric conversion material, for example, NaCo ₂ O ₄ , Bi ₂ Sr ₂ Co ₂ O _x , Ca ₃ BiO _x , or La _1-x Sr _x CoO _y -based material is preferable. As an n-type oxide-based thermoelectric conversion material, a Zn _1-x M _x O (x = 0 to 0.3: M is an element other than Zn) -based oxide, an In—Zn—O-based oxide (In ₂ O ₃ (ZnO) _x (x = 1 to 9) and a mixed sintered body of In ₂ O _{3 and} the like.
[0009]
On the other hand, as the electrode material, metals such as Cu, Al, and Ni, and alloys such as stainless steel can be used. For an n-type thermoelectric conversion material, a stainless alloy having a positive thermoelectromotive force is preferable. For the thermoelectric conversion material, Ni or Cu or the like, whose thermoelectromotive force is negative, is preferable, and the electrode material is preferably linear or thin film. That is, it is preferable to select a material that generates a thermoelectromotive force in the opposite direction to the thermoelectric conversion material as the electrode material.
[0010]
According to the present invention, it is not necessary to configure the thermoelectric conversion module by alternately arranging the p-type thermoelectric conversion materials and the n-type thermoelectric conversion materials, and the thermoelectric conversion module can be configured by one type of thermoelectric conversion material. Even if a temperature gradient is provided between the heat transfer plates disposed opposite to each other, distortion or the like due to a difference in thermal expansion due to the mixture of different materials is less likely to occur, and a thermoelectric conversion module having good durability can be obtained. it can.
[0011]
In the present invention, when a pair of heat transfer plates penetrate each heat transfer plate, and a clamping member that clamps the electrode and the thermoelectric conversion material by tightening these heat transfer plates is provided, the clamping member is It is preferable that one of the heat transfer plates is in contact with the other via a heat insulating material.
As the heat insulating material, it is preferable to use a material having good heat resistance and capable of blocking the flow of heat between the heat transfer plate and the sandwiching member. For example, a material such as ceramic can be used.
According to the present invention, when one of the heat transfer plates is set to a high temperature and the other heat transfer plate is set to a low temperature to provide a temperature gradient between the pair of heat transfer plates, the holding member and the heat transfer member are insulated by the heat insulating material. Since the heat flow between the plates can be shut off, the thermoelectric conversion can be performed more efficiently while maintaining the temperature difference between the heat transfer plates.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a thermoelectric conversion module 1 according to an embodiment of the present invention. The thermoelectric conversion module 1 is configured by interposing two or more thermoelectric conversion materials 13 between a pair of heat transfer plates 11 and 12 opposed to each other.
The heat transfer plates 11 and 12 are each formed of a rectangular alumina plate, and holes 111 and 121 are formed near four corners of the rectangle. Bolts 14 are inserted into the holes 111 and 121 facing each other so as to penetrate the heat transfer plates 11 and 12, and nuts 15 are screwed at ends of the bolts 14. Then, by tightening the bolts 14 and the nuts 15, the plurality of thermoelectric conversion materials 13 are sandwiched between the pair of heat transfer plates 11 and 12, and the bolts 14 and the nuts 15 constitute a sandwiching member.
Further, a ring-shaped member 16 made of ceramic is interposed inside the nut 15, and the bolt 14 that contacts one of the heat transfer plates 11 is transmitted through the ring-shaped member 16 at the portion of the nut 15 to be screwed. The hot plate 12 is tightened. That is, the ring-shaped member 16 functions as a heat insulating material for preventing the heat generated by the heating of the heat transfer plate 11 from being transmitted to the heat transfer plate 12 via the bolts and nuts 14 and 15.
[0013]
The thermoelectric conversion material 13 interposed between such a pair of heat transfer plates 11 and 12 is configured as an n-type thermoelectric conversion material, and extends from one heat transfer plate 11 to the other heat transfer plate 12. It has a cylindrical or prismatic shape. The thermoelectric conversion materials 13 are arranged in a matrix in the rectangular heat transfer plates 11 and 12.
The n-type thermoelectric conversion material 13 can be manufactured, for example, as follows.
[0014]
That is, first, 110.64 g of zinc oxide powder (purity 99.9%, average particle diameter 2 μm) and 9.36 g of cerium oxide (purity 99.9%, average particle diameter 0.4 μm) were weighed and placed in a planetary ball mill. Mix and grind for 20 hours.
Next, this mixture is placed in a beaker, and 120 g of a 1% by weight aqueous PVA solution is added and mixed well.
Then, this is dried in a drier at 90 ° C. for 24 hours, placed in a mortar, and sieved with a 100-mesh sieve while further pulverizing to make the particle size uniform.
[0015]
The obtained powder is placed in a mold and pressed into a columnar body having a length of about 20 mm with an end face of about 5 mm × 5 mm.
The resulting press-formed product was heated from room temperature to 1450 ° C. in 8 hours, held for 10 hours, cooled in 8 hours, and further cooled in the longitudinal direction of the obtained sintered body. The n-type thermoelectric conversion material 13 can be obtained by shaving the surfaces of the end surfaces 131 and 132 by about 2 mm to expose a conductive surface.
[0016]
The thermoelectric conversion material 13 manufactured in this manner is arranged between the pair of heat transfer plates 11 and 12 with the longitudinal direction of the columnar body being the vertical direction. The two adjacent thermoelectric conversion materials 13 are electrically connected by the electrode 17. Connected.
The electrode 17 is formed by bending a sheet made of SUS430 and having a thickness of about 100 μm into a key shape, and has an end face 131 facing one heat transfer plate 11 of the thermoelectric conversion material 13 and the other end face of the thermoelectric conversion material 13 adjacent thereto. The end face 132 facing the heat transfer plate 12 is connected in a crossing manner. When connecting the thermoelectric conversion material 13 and the electrode 17, a metal paste is applied to the conductive surface of the thermoelectric conversion material 13, and the conductive surface of the oxide and the electrode material are bonded by, for example, welding or brazing. Then, the electrode 17 is bonded and fixed. Also, the electrical contact is improved by applying a metal paste, thermal spraying, brazing, or the like to the conductive surface of the oxide, and the thermoelectric conversion material 13 and the electrode 17 are fixed with good electrical contact even when the electrode 17 is mechanically pressed. can do.
Then, these are sequentially connected in the left-right direction and the depth direction in FIG. 1, and a lead wire 18 is connected at an end of the heat transfer plates 11 and 12, and an electric equipment M such as a motor is connected to the lead wire 18. To form a closed circuit.
[0017]
When such a thermoelectric conversion module 1 heats one of the heat transfer plate 11 and the heat transfer plate 12 and cools the other, the end face 131 of the thermoelectric conversion material 13 and the electrode 17 connected to the end face 131, A temperature difference occurs between the end face 132 and the electrode 17 connected to the end face 132, and a current flows through a closed circuit including the thermoelectric conversion material 13, the electrode 17, and the lead wire 18 due to the Seebeck effect, The electric equipment M such as a motor is driven.
[0018]
According to the above-described embodiment, the following effects can be obtained.
(1) The thermoelectric conversion module 1 is configured by arranging a plurality of only one type of thermoelectric conversion material 13 and connecting the adjacent thermoelectric conversion materials 13 in a cross-like manner with the electrodes 17 to form the thermoelectric conversion module 1. The thermoelectric conversion module 1 having less durability and less durability due to the alternate arrangement of the mold and n-type thermoelectric conversion materials can be provided.
[0019]
(2) Since the bolt 14 and the nut 15 as the sandwiching members are connected to the heat transfer plate 12 via the ring-shaped member 16, the heat transfer plate 11 is heated and the heat transfer plate 12 is cooled. Even if the heat of the heat transfer plate 11 flows toward the heat transfer plate 12 via the bolts 14 and the nuts 15, the heat is blocked by the ring upper member 16 and the heat transfer plate 12 is not heated. . Therefore, the thermoelectric conversion module 1 can sufficiently secure the temperature gradient between the heat transfer plates 11 and 12 and can further improve the thermoelectric conversion efficiency.
[0020]
Note that the present invention is not limited to the above-described embodiment, but includes the following modifications.
In the above-described embodiment, the thermoelectric conversion materials 13 are all made of n-type, but the present invention is not limited to this. That is, even if a thermoelectric conversion module is made of a p-type thermoelectric conversion material such as NaCo ₂ O ₄ , Bi ₂ Sr ₂ Co ₂ O _x , Ca ₃ BiO _x , La _1-x Sr _x CoO _y, etc. Good. In this case, it is preferable to use Ni, Cu, or the like as the electrode material. In short, the electrode material employs a material that generates a thermoelectromotive force in a direction opposite to that of the thermoelectric conversion material when a temperature gradient occurs. Is preferred.
[0021]
Further, in the above-described embodiment, zinc oxide powder and cerium oxide are mixed and pulverized, and after stirring and mixing with a PVA aqueous solution, the particle size is adjusted, pressure molding, and sintering are performed. The present invention is not limited to this, and various methods for producing an n-type thermoelectric conversion material can be employed.
In addition, various structures and the like can be adopted as specific structures, material selections, and manufacturing procedures for implementing the present invention as long as the object of the present invention can be achieved.
[0022]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but it should be understood that the present invention is not limited thereto.
(Example)
(1) Preparation of thermoelectric conversion material 110.64 g of zinc oxide powder (purity 99.9%, average particle size of about 2 μm) and 9.36 g of cerium oxide (purity 99.9%, average particle size of about 0.4 μm) were weighed. Then, the mixture was pulverized for 20 hours by a planetary ball mill.
Next, this mixture was placed in a beaker, and 120 g of a 1% by weight aqueous solution of PVA was added and mixed well. This was dried in a drier at 90 ° C. for 24 hours, placed in a mortar, and sieved with a 100-mesh sieve while pulverizing to uniform the particle size.
The resulting powder was placed in a mold and pressed into a rod having a width of about 5 mm, a thickness of about 5 mm, and a length of about 20 mm to obtain five pressed bodies.
The five pressure-molded bodies thus obtained were heated from room temperature to 1450 ° C. in 8 hours, held for 10 hours, and then cooled to room temperature in 8 hours to obtain 5 sintered bodies. Obtained.
[0023]
(2) Manufacture of thermoelectric conversion module The end face in the long axis direction of each sintered body obtained by the above-mentioned method was shaved off by about 2 mm, and a conductive surface was obtained, thereby obtaining n-type thermoelectric conversion material 13 in FIG. After electroless plating of Ni on the conductive surface, a SUS430 sheet having a thickness of 100 μm was cut into a strip having a width of about 7 mm and a length of 45 mm.
This sheet is bent at 15 mm from both ends to form a crank-shaped sheet, and the 15 mm end portion is brazed to the conductive surface of the n-type thermoelectric conversion material 13 with silver brazing. 13 were connected and mounted on an alumina substrate as the heat transfer plate 11 to produce the thermoelectric conversion module 1.
[0024]
(Comparative example)
(1) Preparation of thermoelectric conversion material A mixed sintered body of zinc oxide and cerium oxide was prepared in the same manner as in the example, and was used as an n-type thermoelectric conversion material 102 and a p-type oxide thermoelectric conversion material 101 of NaCo ₂ O ₄ oxide. A sintered body was used.
(2) Manufacture of thermoelectric conversion module A thermoelectric conversion module in which the π-type thermoelectric conversion element shown in FIG. 2 is continuous was manufactured using the above two types of n-type thermoelectric conversion materials 102 and p-type oxide thermoelectric conversion materials 101. . Specifically, three n-type thermoelectric conversion materials 102 and two p-type oxide thermoelectric conversion materials 101 are prepared, and after these are alternately arranged, the n-type thermoelectric conversion material 102 and the p-type thermoelectric conversion material 101 are prepared. Are connected by a metal segment 103 serving as an electrode, and mounted on an alumina substrate to form a thermoelectric conversion module. In addition, as for the bonding with the electrode, a zinc oxide-based material is electrolessly plated with Ni to form a conductive surface, and a NaCo ₂ O ₄ oxide is used as it is, using a SUS430 100 μm sheet in the same manner as in the embodiment. The sheet was electrically connected to the conductive surface by brazing it with a silver braze, and was placed on an alumina substrate to produce a thermoelectric conversion module.
[0025]
(Evaluation method)
The thermoelectric conversion modules obtained in Examples and Comparative Examples were placed on a hot plate, the temperature of the hot plate was raised to 450 ° C. over 5 minutes, and then held for 20 minutes, and then returned to room temperature for one cycle. A heat cycle test was performed 10 times, and after the heat cycle test, the appearance change, thermoelectromotive force, and resistance value of each thermoelectric conversion module were measured.
(result)
In the thermoelectric conversion module according to the example, no change in appearance was observed, and no change was observed in the thermoelectromotive force and the resistance value.
On the other hand, the thermoelectric conversion module according to the comparative example had a crack near the brazing of the n-type thermoelectric conversion material, and when the resistance of the thermoelectric conversion module was measured, the resistance was infinite.
From the above, it was confirmed that the thermoelectric conversion module according to the example was a thermoelectric conversion module having good durability without any distortion of the thermoelectric conversion material.
[0026]
【The invention's effect】
According to the present invention as described above, since a thermoelectric conversion module can be constituted by one type of thermoelectric conversion material, distortion occurs in the thermoelectric conversion material even when a temperature gradient is provided between the heat transfer plates disposed to face each other. Thus, a thermoelectric conversion module having good durability can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view illustrating a structure of a thermoelectric conversion module according to an embodiment of the present invention.
FIG. 2 is a schematic sectional view showing the structure of a conventional π-type thermoelectric conversion module.
[Explanation of symbols]
11, 12 Heat transfer plate 1 Thermoelectric conversion module 13 Thermoelectric conversion material 17 Electrode 14, 15 Bolt / nut (clamping member)
16 Ring-shaped member (heat insulating material)

Claims (4)

A thermoelectric conversion module that converts a temperature gradient generated between a pair of heat transfer plates disposed to face each other into electric energy,
It comprises a plurality of thermoelectric conversion materials interposed between the pair of heat transfer plates, each extending from one heat transfer plate toward the other heat transfer plate,
A thermoelectric conversion module, wherein end faces of two adjacent thermoelectric conversion materials facing different heat transfer plates are connected by electrodes made of a metal or an alloy different from the thermoelectric conversion material. The thermoelectric conversion module according to claim 1,
The thermoelectric conversion module, wherein the thermoelectric conversion material is an oxide-based thermoelectric conversion material. 3. The thermoelectric conversion module according to claim 1, wherein the electrode generates a thermoelectromotive force in a direction opposite to the thermoelectric conversion material when a temperature gradient occurs between the pair of heat transfer plates. 4. A thermoelectric conversion module comprising a material. The thermoelectric conversion module according to any one of claims 1 to 3,
The pair of heat transfer plates, penetrating each heat transfer plate, is provided with a holding member for holding the electrode and the thermoelectric conversion material by tightening these heat transfer plates,
The holding member is in contact with one of the heat transfer plates via a heat insulating material.

Images