JP2000077732A - Thermoelectric conversion device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the production cost of a thermoelectric conversion device and to give larger scale capability of a generating power to the device. SOLUTION: This device is provided with a tabular base material 11 which circulates each of a heat source fluid and a cooling fluid in or on either of the interior thereof and the outside thereof, and a thermoelectric conversion element 13. The element 13 is formed by depositing N-type semiconductor layers 5 and P-type semiconductor layers 6 on the outer peripheral surface of the base material 11, generates power by a temperature difference between the heat of the junction surface of the element 13 and the base material 11 and the heat of the outermost peripheral surface of the element 13, and consists of pairs of the bondings of the semiconductor layers 5 to the semiconductor layers 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a thermoelectric direct conversion technology among energy conversion material technologies.

[0002]

2. Description of the Related Art Direct conversion of heat energy to electricity by a semiconductor material using the Seebeck effect was proposed by Joffe in the 1950's, and subsequently, for example, by Bi.
-Te system, Pb-Te system, Ge-Si-based, various semiconductor materials and SiC, such as Fe-Si-based, ceramic materials, such as B ₄ C have been investigated as a thermoelectric conversion material. Among them, thermoelectric converters using Bi-Te / Pb-Te semiconductors with relatively high conversion efficiency have been developed mainly in the United States and the former Soviet Union. It has been used by combining. In recent years, refrigerators utilizing a heat absorption effect (Peltier effect) by electric energy have recently been put to practical use using Bi-Te-based semiconductors. In these thermoelectric conversion devices, a single crystal material obtained by a zone melt method or a sintered material obtained by a powder sintering method has been mainly used as a thermoelectric conversion material. Since the thermoelectric conversion material manufactured by the method is a high-purity semiconductor material, a thermoelectric conversion element using the material has to be expensive, which has been an obstacle to the spread of thermoelectric direct power generation. .

[0003]

The thermoelectric power generation technology has no moving parts, has a long service life, has a very low maintenance burden as compared with other power generation methods, and is applicable to temperature and heat quantity fluctuations of a heat source. Because of its wide area, it is expected as a technology to recover unused energy. However, in order to cope with a relatively large-scale heat source such as high-temperature combustion gas from a garbage incinerator or coke cooling heat from an ironworks, a power generator based on the thermoelectric conversion element manufacturing technology according to the conventional method as described above is required. , Capacity and economy. There is an urgent need to solve this problem in order to use thermoelectric power generation technology in the heat recovery field.

[0004] The present invention has been made to meet the demands of the present situation, and, unlike the conventional method in which a large number of single crystals or sintered materials are integrated, the manufacturing cost is reduced and compared with the conventional method. To provide a thermoelectric generator having a large-scale power generation capability and a method of manufacturing the same.

[0005]

As a result of various studies, the inventors of the present invention have formed an n-type semiconductor and a p-type semiconductor on a tubular substrate by using a spraying technique which has not been applied conventionally. It has been found that the above object can be achieved by forming a thermoelectric conversion element composed of a junction pair of the semiconductor, and the present invention has been completed.

That is, the present invention is formed by depositing and forming a thermoelectric material on the outer peripheral surface of a tubular base material through which a heat source fluid and a cooling fluid flow either inside or outside. A thermoelectric conversion element that generates electric power by a temperature difference between a bonding surface of the tubular base material and an outermost peripheral surface,
The thermoelectric conversion material is an n-type semiconductor and a p-type semiconductor, and the thermoelectric conversion element is a junction pair of the semiconductor.

[0007] Preferably, the tubular substrate is made of a conductive material, and an electrical insulating film formed by deposition on the outer peripheral surface of the tubular substrate; A plurality of electrically insulating rims formed by precipitation at intervals along the axial direction of the material; and a plurality of thermoelectric conversion elements formed by precipitation in the gap on the outer peripheral surface of the electrically insulating film. ,
The thermoelectric conversion element and a conductive film deposited and formed on the outer peripheral surface of the electrically insulating rim, wherein the thermoelectric conversion element is an n-type semiconductor and a p-type semiconductor that are in contact with each other in the axial direction of the tubular substrate.
A concave portion for electrically separating the n-type semiconductor and the p-type semiconductor at the interface between the n-type semiconductor and the p-type semiconductor at an interface between the n-type semiconductor and the p-type semiconductor except for one end near the tubular substrate. Place is established.

Alternatively, the tubular base is made of an electrically insulating material, and a plurality of electric conductors are formed on the outer peripheral surface of the tubular base by deposition along the axial direction of the tubular base with a gap therebetween. An insulating rim, a plurality of the thermoelectric conversion elements deposited and formed in the gap on the outer peripheral surface of the tubular substrate, and a conductive material deposited and formed on the outer peripheral surfaces of the thermoelectric conversion element and the electrically insulating rim. A thermoelectric conversion element, the thermoelectric conversion element comprises a junction pair of an n-type semiconductor and a p-type semiconductor that are in contact with each other in the axial direction of the tubular base material, and at an interface between the n-type semiconductor and the p-type semiconductor, A recess is provided for electrically separating the n-type semiconductor and the p-type semiconductor except for one end near the tubular substrate.

Alternatively, the tubular base is made of an electrically insulating material, a plurality of grooves provided on the outer peripheral surface of the tubular base at intervals along an axial direction, and a plurality of grooves are formed in the grooves. A plurality of the formed thermoelectric conversion elements, and a conductive film deposited and formed on the outer peripheral surfaces of the thermoelectric conversion elements and the groove walls, wherein the thermoelectric conversion elements are arranged in the axial direction of the tubular base material. At the interface between the n-type semiconductor and the p-type semiconductor, leaving one end near the tubular substrate at the interface between the n-type semiconductor and the p-type semiconductor.
A recess is provided for electrically separating the mold semiconductor.

The present invention also provides a method for manufacturing a thermoelectric converter.

That is, the present invention is characterized in that an n-type semiconductor and a p-type semiconductor are deposited and formed on the outer peripheral surface of a tubular base material by a thermal spraying method to form a thermoelectric conversion element comprising a bonding pair of the semiconductors. An object of the present invention is to provide a method for manufacturing an electric conversion device.

Preferably, the method for manufacturing a thermoelectric converter according to the present invention comprises the steps of: depositing and forming an electrically insulating film on an outer peripheral surface of a tubular base made of a conductive material; A step of depositing and forming a plurality of electrically insulative rims at intervals along the axial direction of the tubular base material by a thermal spraying method on the outer peripheral surface of the n-type semiconductor; A step of forming a thermoelectric conversion element by sequentially forming a p-type semiconductor so that the p-type semiconductors are arranged side by side in the axial direction of the tubular substrate to form a thermoelectric conversion element, and on the outer peripheral surfaces of the thermoelectric conversion element and the electrically insulating rim, by a thermal spray method, Depositing and forming a conductive film, and electrically separating the n-type semiconductor and the p-type semiconductor at an interface between the n-type semiconductor and the p-type semiconductor except for one end near the tubular substrate. Providing a recess to be formed.

Alternatively, a plurality of electrically insulative rims are formed on the outer peripheral surface of a tubular base made of an electrically insulative material by a thermal spraying method at intervals along the axial direction of the tubular base. Forming a thermoelectric conversion element by sequentially forming an n-type semiconductor and a p-type semiconductor in the gap by a thermal spraying method so that the n-type semiconductor and the p-type semiconductor are arranged side by side in the axial direction of the tubular substrate. A step of depositing and forming a conductive film on the outer peripheral surfaces of the element and the electrically insulating rim by a thermal spraying method, and leaving one end near the tubular base material at an interface between the n-type semiconductor and the p-type semiconductor. Providing a recess for electrically separating the n-type semiconductor from the p-type semiconductor.

Alternatively, a step of providing a plurality of grooves at intervals along the axial direction on the outer peripheral surface of a tubular base made of an electrically insulating material, and forming the grooves in the grooves by thermal spraying. A step of forming a thermoelectric conversion element by sequentially forming a semiconductor and a p-type semiconductor in a line in the axial direction of the tubular substrate to form a thermoelectric conversion element, and on the outer peripheral surfaces of the thermoelectric conversion element and the groove wall, by a thermal spraying method, Depositing and forming a conductive film, and electrically separating the n-type semiconductor and the p-type semiconductor at an interface between the n-type semiconductor and the p-type semiconductor except for one end near the tubular substrate. Providing a recess to be formed.

The n-type semiconductor and the p-type semiconductor are continuously deposited in the circumferential direction on the surface of the base material by continuously rotating the base material or the spraying apparatus in the thermal spray manufacturing process. Therefore, it is possible to provide a thermoelectric conversion device that includes a large-area thermoelectric conversion element that can handle large-scale power generation and that has reduced manufacturing costs.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view schematically showing an embodiment of a thermoelectric converter using a conductive tubular substrate according to the present invention, and FIG. 2 is an enlarged vertical sectional view of a portion A in FIG. . FIG. 3 shows an embodiment of a manufacturing process of the thermoelectric converter shown in FIG.

As shown in FIG. 1, a thermoelectric converter 1 using a conductive tubular substrate according to the present invention comprises an n-type semiconductor 5 and a p-type semiconductor 5.
This is a configuration in which thermoelectric conversion elements 13 in which the mold semiconductors 6 form a pair are continuously arranged in multiple stages in the axial direction of the conductive tubular substrate 11. The thermoelectric conversion element 13 is formed by forming a pair of the n-type semiconductor 5 and the p-type semiconductor 6 into a pair, and having a suitable width on the tubular base material 11 and depositing the ring in the circumferential direction. As shown in FIG. 2, the adjacent thermoelectric conversion elements 13 are electrically separated from each other by the previously formed electrically insulating film 2 and the electrically insulating rim 3. They are electrically connected by the conductive film 4 deposited thereon. 1
At the interface between the n-type semiconductor 5 and the p-type semiconductor 6 constituting one thermoelectric conversion element 13, a recess 7 is provided except for one end near the tubular base material 11, and the one end electrically connects to each other. Is bound to. Therefore, each thermoelectric conversion element 13 forms an electric circuit on the outer surface of the tubular substrate 11.

When power is generated using the present apparatus 1, a high-temperature fluid is supplied to the inside of the tubular substrate 11 and a cooling fluid is supplied to the outside, or conversely, a cooling fluid is supplied to the inside and the high-temperature fluid is supplied to the outside. Causes a temperature difference in the thermoelectric conversion element 13 between the bonding surface with the electrically insulating film 2 and the outermost surface. Due to the Seebeck effect based on the temperature difference, a potential difference is generated between the inner and outer surfaces of the thermoelectric conversion element 13, and when a circuit is formed by connecting an appropriate load resistance to the outside, a current flows and power generation is possible.

Hereinafter, a method of manufacturing the thermoelectric converter 1 using the conductive tubular substrate 11 will be described.

(1) As shown in FIG. 3 (a), the outer peripheral surface of a cylinder made of a conductive metal or a conductive tubular substrate 11 having an arbitrary cross-sectional shape is roughened in advance. This roughening is performed by a suction type or pressure type blasting device, using a casting grid, alumina powder, silicon carbide powder, silica sand, or the like as a blast material, and blasting so that the average roughness is 2.5 to 13 μm. This is done by:

(2) Next, as shown in FIG. 3B, an electrically insulating film 2 is deposited by thermal spraying. The deposition of the electrically insulating film 2 by thermal spraying is performed, for example, by using a plasma thermal spraying apparatus, using argon, hydrogen, or the like as a plasma gas, and applying a thermal spray material powder to be applied to an arc discharge plasma flame to perform thermal spray molding. Made by Conditions such as the fuel device, gas flow rate, and electricity are appropriately selected according to the thermal spraying device and thermal spray material. For example, when plasma spraying is carried out using alumina as a spray material, argon gas is used as plasma gas, and spraying is performed in the air at a plasma power of 25 kW and a spray distance of 100 mm. The insulating film 2 is intended to prevent an electrical short circuit between the thermoelectric conversion elements 13, and thus may have a minimum thickness that can guarantee electrical insulation. For example, when using alumina as an insulating material,
Normally, it is sufficient to deposit to a thickness of 200 to 500 μm. In addition, in addition to the case where the insulating film 2 is deposited over the entire length of the tubular base material 11, the end of the tubular base material 11 has an insulating property to serve as a grip portion or a welded portion for mechanically fixing the thermoelectric conversion device. The coating 2 may not be deposited.

(3) Next, as shown in FIG. 3 (c), in order to electrically insulate the thermoelectric conversion elements 13, the electrically insulating rims 3 are formed on the insulating film 2 at predetermined intervals. To form As the material of the insulating rim 3, an insulating ceramic material is preferable, and it is necessary to appropriately select the material in consideration of the thermal expansion coefficients of the thermoelectric conversion materials 5 and 6. For example, when iron silicide is used as the thermoelectric conversion materials 5 and 6, a silicate such as zirconium oxide or Mg ₂ SiO ₄ is preferable. The thickness of the insulating rim 3 along the radial direction of the tubular substrate 11 needs to be adjusted to the thickness of the finally formed thermoelectric conversion element 13. Further, the width of the insulating rim 3 along the axial direction of the tubular base material 11 may be a width sufficient to insulate, but from the viewpoint of molding accuracy by thermal spraying, it is about several mm, preferably 2 mm to 5 mm. It is said. The spacing between the insulating rims 3 depends on the design of the thermoelectric conversion element 13,
In consideration of the accuracy of thermal spray molding, the thickness is preferably about 5 mm to 50 mm, and more preferably 10 mm to 20 mm.

(4) Next, as shown in FIGS. 3D and 3E, an n-type semiconductor 5 and a p-type semiconductor 6 are sequentially formed between the insulating rims 3. N-type semiconductor 5 and p by thermal spraying
The molding of the mold semiconductor 6 is performed, for example, by using a high-speed flame spraying apparatus, forming a high-speed combustion flame using kerosene or propane gas as a fuel and oxygen as an oxidizing agent, and adding a semiconductor powder as a spray material to the flame. This is performed by performing thermal spray molding. The thickness of the semiconductors 5 and 6 is appropriately determined in consideration of heat source and cooling source temperatures and electrical optimization. However, the maximum thickness that can be formed exists depending on the thermal spraying method, the temperature at the time of thermal spraying of the thermal spray material and the substrate, and the cooling of the thermal spray substrate and the thermal sprayed surface. For example, when spraying iron silicide by plasma spraying, even if the sprayed surface is cooled with an inert gas during the spraying, when the thickness of the formed body exceeds 5 mm, the formed body tends to peel off from the base material. . This is because the thermal sprayed material, which has become high temperature during thermal spraying, accumulates tensile stress inside during cooling, and when the thickness exceeds a predetermined value, the combined stress exceeds the adhesive strength.

(5) Next, as shown in FIG. 3F, after the thermoelectric conversion materials 5 and 6 are all formed by thermal spray molding, a conductive film 4 is formed thereon. As the conductive film 4,
Copper, iron, stainless steel, nickel, nickel-based alloys and the like are preferred. The conductive coating 4 is formed by thermal spraying, for example, by using a low-pressure plasma thermal spraying apparatus, using argon as a plasma gas, and charging the conductive powder of interest into a plasma flame to perform thermal spray molding. When spraying copper, in an argon atmosphere at a pressure of 20 kPa,
Argon gas as plasma gas, plasma power 25k
W, thermal spraying is performed at a thermal spray distance of 300 mm. The thickness of the conductive film 4 is determined in consideration of an assumed temperature difference between the heat source and the cooling source, and an optimum electric resistance with respect to the voltage and current depending on the area of the thermoelectric elements 5 and 6. But usually 10
0 μm to 500 μm, preferably 100 μm to 300 μm
It is said.

(6) Finally, the concave portion 7 is formed by removing the interface between the conductive film 4 and the np elements 5 and 6 by machining, electric discharge machining, laser machining, or the like, thereby forming a thermocouple structure. To When the recess 7 is formed by mechanical processing, ordinary lathe processing, cutting using a rotating grindstone, or the like can be used. The cut thickness may be sufficient to ensure electrical insulation between the n-p poles 5 and 6;
The thickness is from 00 μm to 3 mm, preferably from 1 mm to 2 mm. The length of the contact portion between the np elements 5 and 6 is 1 to 2
It is cut to a depth of about mm. That is, when the thickness of the thermoelectric material layer is about 5 mm, the recess 7
Has a depth of about 3 to 4 mm.

According to the above-described thermoelectric converter 1 and the method of manufacturing the same, it is advantageous that the conductive film 4 only needs to be formed on one of the inside and the outside of the n-type semiconductor 5 and the p-type semiconductor 6. . That is, if the thermoelectric conversion elements are formed using only one of the n-type semiconductor and the p-type semiconductor and are arranged in multiple stages continuously in the axial direction of the tubular substrate, each thermoelectric conversion element has a potential difference in the same direction. Is generated. In this case, in order to electrically couple each thermoelectric conversion element, a conductive film is formed on both inner and outer sides of the thermoelectric conversion element, and a conductive film on one inner side of the adjacent thermoelectric conversion element and a conductive film on the other outer side are formed. It is necessary to connect electrically to the conductive film. In the thermoelectric conversion device 1 according to the present invention, since the conductive film 4 is formed only on one of the inside and outside of the thermoelectric conversion element 13, the gap between the adjacent thermoelectric conversion elements 13 can be inevitably narrowed, Substrate 1
1, the thermoelectric conversion elements 13 can be formed at a high density. Therefore, a larger amount of current can be taken out, and heat exchange between the high-temperature fluid and the low-temperature fluid through the gap can be suppressed, thereby providing a thermoelectric converter with extremely excellent conversion efficiency. Further, since the conductive film 4 only needs to be formed outside the thermoelectric conversion element 13, the manufacturing process is shortened, and the manufacturing cost is also reduced.

FIG. 4 is an enlarged vertical sectional view showing a part of a thermoelectric converter using the electrically insulating tubular substrate according to the present invention. FIG. 5 shows an embodiment of a manufacturing process of the thermoelectric converter shown in FIG.

The thermoelectric conversion device 1 using the electrically insulating tubular base material according to the present invention is similar to the thermoelectric conversion device using the conductive tubular base material shown in FIG. In this configuration, the thermoelectric conversion elements 13 in which the semiconductors 6 form a pair are continuously arranged in multiple stages in the axial direction of the electrically insulating tubular base material 12. As shown in FIG. 4, the adjacent thermoelectric conversion elements 13 are electrically separated by the tubular base material 12 and the electrically insulating rim 3. Electrically connected by the conductive film 4. At the interface between the n-type semiconductor 5 and the p-type semiconductor 6 constituting one thermoelectric conversion element 13, a recess 7 is provided except for one end near the tubular base material 11, and the one end is electrically connected to each other. Tied together. Therefore, each thermoelectric conversion element 13 is
An electric circuit is formed on the outer surface.

Hereinafter, a method for manufacturing the thermoelectric conversion device 1 using the electrically insulating tubular substrate 12 will be described.

When an insulating material such as ceramics is used as the material of the tubular base material 12, the thermal spraying of the insulating coating 2 shown in FIG. The process can be started from the step of forming the electrically insulating rim 3 (FIG. 5B). Subsequent steps are the same as in the case of using the conductive tubular substrate 11, and are steps of depositing and forming the n-type semiconductor 5 and the p-type semiconductor 6 (FIG. 5 (c),
(D)), a step of forming the conductive film 4 (FIG. 5 (e)),
The thermoelectric conversion device 1 is manufactured through the step of forming the recess 7 by removing the interface between the n-type semiconductor 5 and the p-type semiconductor 6 (FIG. 5F).

FIG. 6 is an enlarged vertical sectional view showing a part of a thermoelectric converter according to another embodiment using the electrically insulating tubular substrate according to the present invention. FIG. 7 shows an embodiment of a manufacturing process of the thermoelectric converter shown in FIG.

The thermoelectric conversion device 1 according to the present embodiment has a thermoelectric conversion device in which an n-type semiconductor 5 and a p-type semiconductor 6 are paired as in the thermoelectric conversion device using the conductive tubular substrate shown in FIG. In this configuration, the conversion elements 13 are continuously arranged in multiple stages in the axial direction of the electrically insulating tubular base material 12. As shown in FIG. 6, the adjacent thermoelectric conversion elements 13 are electrically separated by the tubular base 12 and the insulating rim 3, but the conductive film deposited on the element 13 across the insulating rim 3 4 are electrically connected. At the interface between the n-type semiconductor 5 and the p-type semiconductor 6 constituting one thermoelectric conversion element 13, a recess 7 is provided except for one end near the tubular base material 11, and the one end is electrically connected to each other. Tied together. Therefore, each thermoelectric conversion element 13 forms an electric circuit on the outer surface of the tubular substrate 12.

As shown in FIGS. 7A and 7B, the manufacturing method of the thermoelectric conversion device 1 according to the present embodiment is as follows. Start by molding 3. The grooving can be performed not only by cutting but also by blasting or the like in combination with masking. Alternatively, an electrically insulating tubular base material previously formed as shown in FIG. 7B may be used. Subsequent steps are the same as the manufacturing steps shown in FIG. 5, and include steps of depositing and forming the n-type semiconductor 5 and the p-type semiconductor 6 (FIGS. 7 (c) and (d)).
Through the step of forming the conductive film 4 (FIG. 7E) and the step of removing the interface between the n-type semiconductor 5 and the p-type semiconductor 6 to form the recess 7 (FIG. 7F), The electric conversion device 1 is manufactured.

According to the thermoelectric conversion device 1 using the electrically insulating tubular base material 12 and the method of manufacturing the same, as in the thermoelectric conversion device using the conductive tubular base material 11 described above, the conductive material This is advantageous in that the conductive film 4 only needs to be formed on one of the inside and the outside of the n-type semiconductor 5 and the p-type semiconductor 6.
That is, the thermoelectric conversion elements 13 are densely placed on the tubular base 12.
Can be formed, and more current can be extracted. Further, heat exchange between the high-temperature fluid and the low-temperature fluid through the gap between the adjacent thermoelectric conversion elements 13 can be suppressed, and a thermoelectric conversion device with extremely excellent conversion efficiency is provided. Further, since the conductive film 4 needs to be formed only on the outside of the thermoelectric conversion element 13, the manufacturing process is shortened, and the manufacturing cost is also reduced.

As described above, the conductive tubular substrate 11
Alternatively, the thermoelectric conversion device 1 in which the thermoelectric conversion elements 13 are arranged continuously in multiple stages in the axial direction of the tubular base material using the electrically insulating tubular base material 12 can be manufactured. When power is generated using the present apparatus 1, high-temperature fluid serving as a heat source such as high-temperature water, high-temperature gas, or steam flows through the tubes 11 and 12 so that the thermoelectric conversion element 13
The bottom surface is heated, and at the same time, the outside of the device 1 is cooled with air, water, or the like, so that the outer surface of the thermoelectric conversion element 13 is cooled. As a result, a temperature difference occurs in the thermoelectric conversion element 13, and a potential difference occurs due to the thermoelectric action. When a circuit is formed by connecting an appropriate load resistor to the outside, a current flows and power generation is possible.

There is no problem when the outer surface is cooled by air or gas. However, when the outer surface is cooled by a conductive fluid such as industrial water, groundwater or river water, the voltage between the thermoelectric conversion elements 13 is short-circuited. Would. In this case, an insulating film may be further formed on the outer surface after the formation of the recess 7 described above. As the insulating coating, a thin layer of ceramics or plastic is suitable.

Incidentally, the outer surface of the thermoelectric converter 1 may be heated so that a cooling fluid flows through the inside of the tubular substrates 11 and 12. Whether to heat the inside of the base material or the outer surface of the apparatus can be selected depending on a heating source and a cooling source that can be used.

In the thermal spraying method, a high-temperature and high-speed gas flow is generated by electric plasma or flame combustion, and powder or a linear material of a thermal spraying material as a raw material is continuously charged into the plasma or the combustion flame to perform thermal spraying. Melting of the material by high temperature,
This is a technique of coating the thermal spray material on the surface of a substrate by simultaneously performing projection (spraying) by a high-speed gas flow.
In recent years, it has become possible to form a coating with a thickness of several mm to several cm by appropriately controlling the temperature of the substrate during the thermal spraying process. The feature of the thermal spraying method is that the material can be deposited and coated at a high speed, and since the material is once melted and formed, the bonding between the material particles formed by cooling and solidifying the molten droplets is strong, and the sintering method is used. The point is that a material having a strength close to the above can be molded. In particular, according to the plasma spraying method under reduced pressure atmosphere conditions, the amount of residual pores in the material formed by precipitation can be made extremely small, and the material does not undergo deterioration such as oxidation during the formation. In the case where the semiconductor material used as the thermoelectric conversion material of the thermoelectric conversion device according to the present invention is deposited and formed, the composition is suppressed by plasma spraying under reduced-pressure atmosphere conditions, and the element having more excellent characteristics is suppressed. Can be formed.

Another advantage of the thermal spraying method is that it is economical. In the conventional single crystal method or powder sintering method, a prolonged high-temperature heating process is inevitable, and the production efficiency is low due to the extremely slow crystal growth rate and sintering rate. Are also very expensive. On the other hand, in the thermal spraying method, melting and precipitation are performed instantaneously and continuously, so that a large amount of raw material can be manufactured as a compact in a short time. In ordinary plasma spraying, the amount of the powder raw material charged into the plasma is about 30 g per minute. Although it depends on the conditions, usually about 80% of the charged amount can be molded, so that approximately 1.5 kg of powder can be molded by one hour of thermal spraying. This is a very high-speed manufacturing process as compared with single crystal pulling, zone melt method, or powder sintering method, which requires several days to ten to several days. In particular, in the single crystal method and the powder sintering method, it is extremely rare that a compact is obtained in a shape intended for final use, and a great deal of labor is required for post-processing such as cutting, surface grinding, and chamfering after molding. on the other hand,
In the thermal spraying method, since the molding is performed while sequentially forming the shape along the shape of the base material, the final target shape can be finished in one manufacturing process. Further, in the case of the thermoelectric conversion device according to the present invention, since the purpose is to mold a thermoelectric conversion element having an electromagnetic function, unlike the purpose of abrasion resistance, etc., the surface processing of the thermal spray coating after molding is at a minimum level. That is, it is possible to finish the surface with a polishing material (silicon carbide, diamond, or the like) having a particle size of # 200 to # 400 as the rough surface polishing.

The substrate 11 of the thermoelectric converter 1 according to the present invention
When a normal steel material is used, a high-temperature fluid up to about 600 ° C. is used for the substrate 1 in consideration of oxidation of the material in the atmosphere.
1 can flow inside or outside. Therefore, in this case, the thermoelectric conversion material is a semiconductor thermoelectric conversion material that operates below the temperature, Bi-Te-based, Bi-Sb-based, Pb-based.
-Te-based, Ge-Te-based, Ga-Se-based, Fe-Si-based or Co-Si-based can be used. In the case where a fluid having a higher temperature is used, a ceramic fluid such as Al ₂ O ₃ is used for the substrate 12, so that a high-temperature fluid of about 1,000 ° C. can be flowed into or out of the substrate 12. In this case, the thermoelectric conversion material is Ge-Si based, Si-C based or B-based.
A material such as a -C type material can be used. As the thermoelectric conversion material, any of the above-mentioned various materials can be used as long as it is a solid material having a melting point that allows thermal spraying, and can be optimally selected according to the heat source used. Further, the thickness and area of the thermoelectric conversion material deposited and formed on the base material, the thermoelectric properties and heat conduction properties of the material, and the temperature of the heat source, the flow rate and the temperature of the cooling fluid,
It is optimally designed in consideration of the flow rate and the like. Thermoelectric conversion element 13
Can be designed to meet the heat source and the intended purpose of the extracted electrical energy.

An electric insulating material 2 coated on the conductive base material 11 to achieve electric insulation between the thermoelectric conversion materials 5 and 6
Is a heat-resistant resin in a low temperature range of 200 ° C. or less,
In a temperature range of 200 ° C. or higher, a ceramic material usually used for insulating purposes can be used. The ceramic material can be a sprayable oxide ceramic such as alumina, zirconia, or mullite, or various ceramic materials used for insulators. When the temperature is not very high (1000 ° C. or lower), the electric insulating material 2 can be glass or crystallized glass material. One of these materials, or a combination of two or more materials to match the thermal expansion of the substrate, can be sprayed to a thickness of a few hundred μm to a few mm required for insulation. However, if the coating is excessively thick, the thermal conductivity is reduced, so that the desired temperature difference cannot be given to the thermoelectric conversion element 13 and the performance of the thermoelectric conversion device 1 is reduced.

The conductive film 4 for electrical connection between the multi-stage thermoelectric conversion elements 13 is made of ordinary copper, silver, aluminum,
Alternatively, these alloys can be used. The conductive film 4 has a predetermined thickness calculated in advance so as not to cause excessive electrical resistance loss according to the generated voltage.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of a result of manufacturing a thermoelectric converter using the method of manufacturing a thermoelectric converter according to the present invention and performing thermoelectric conversion by the thermoelectric converter will be described. Alumina was sprayed on the outer periphery of the center of a SUS430 stainless steel pipe (0.7 mm thick) having a diameter of 2.5 cm and a length of 50 cm over a length of 200 μm and a length of 30 cm in the pipe longitudinal direction by a plasma spraying method. Next, M
g ₂ SiO ₄ as insulating rim material, thickness 3mm, interval 20m
m were molded into 13 pieces. Next, Co is used as an n-type semiconductor.
Atomic% -containing iron silicide (FeSi ₂ ) was formed by plasma spraying to have a width of 1 cm and a thickness of 2.8 mm.
Next, in a region adjacent to the n-type semiconductor, an iron silicide containing 4 atomic% of Al as a p-type semiconductor has a width of 1 cm,
Thermal spray molding was performed with a thickness of 2.8 mm. From above, copper was sprayed by flame spraying over the entire circumference of the pipe to a thickness of about 200 μm. Finally, the n-p interface was cut with a diamond blade having a thickness of 1 mm, and the n-pole and the p-pole were separated except for the connection part on the bottom surface. The thermoelectric conversion device manufactured in this manner is placed in an electric furnace, and the surface of the thermoelectric material layer is cleaned by 60%.
By heating to 0 ° C. and flowing cooling air through the tube, a temperature difference of 500 ° C. was provided on the inner and outer surfaces of the thermoelectric conversion material. At this time, by connecting an external resistance of 1Ω,
2.4V, 2.4A of electricity was generated in the circuit.

[0044]

As described above, the thermoelectric conversion device according to the present invention has a configuration in which a thermoelectric conversion element is formed by a junction pair of an n-type semiconductor and a p-type semiconductor. When a plurality of thermoelectric conversion elements are continuously arranged in the axial direction, the gap between adjacent thermoelectric conversion elements can be narrowed, and the thermoelectric conversion elements can be formed on the tubular base material at high density. Therefore, a larger amount of current can be taken out, and heat exchange between the high-temperature fluid and the low-temperature fluid through the gap can be suppressed, thereby providing a thermoelectric converter with extremely excellent conversion efficiency.

According to the method for manufacturing a thermoelectric conversion device according to the present invention, the substrate or the spraying device is continuously rotated in the thermal spraying production process in order to deposit and form the thermoelectric conversion element using the thermal spraying method. It can be deposited continuously in the circumferential direction on the substrate surface. Therefore, unlike the conventional manufacturing method in which a large number of single crystals or sintered materials are integrated, manufacturing costs are reduced. Furthermore, since a thermoelectric conversion element is formed by a junction pair of an n-type semiconductor and a p-type semiconductor, an electric connection between adjacent thermoelectric conversion elements, which is necessary when the thermoelectric conversion elements are arranged in multiple stages continuously in the axial direction of the base material. Need only be formed on the outermost surface, the manufacturing process can be shortened, and the manufacturing cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing an embodiment of a thermoelectric converter using a conductive tubular substrate according to the present invention.

FIG. 2 is an enlarged vertical sectional view of a portion A in FIG. 1;

FIG. 3 shows an embodiment of a manufacturing process of the thermoelectric converter shown in FIG.

FIG. 4 is an enlarged vertical sectional view showing a part of a thermoelectric converter using the electrically insulating tubular base material according to the present invention.

FIG. 5 shows an embodiment of a manufacturing process of the thermoelectric converter shown in FIG.

FIG. 6 is an enlarged vertical sectional view showing a part of a thermoelectric converter according to another embodiment using the electrically insulating tubular base material according to the present invention.

7 shows an embodiment of a manufacturing process of the thermoelectric converter shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 thermoelectric conversion device 2 electric insulating film 3 electric insulating rim 4 conductive film 5 n-type semiconductor 6 p-type semiconductor 7 recess 11 conductive tubular base material 12 electrically insulating tubular base material 13 thermoelectric conversion element

Claims (8)

[Claims] 1. A tubular base material in which a heat source fluid and a cooling fluid flow either inside or outside, and a thermoelectric conversion material formed on an outer peripheral surface of the tubular base material by precipitation molding. A thermoelectric conversion element that generates electric power by a temperature difference between a bonding surface with the material and an outermost peripheral surface, wherein the thermoelectric conversion material is an n-type semiconductor and a p-type semiconductor; A thermoelectric converter characterized by being a bonded pair. 2. The tubular base material is made of a conductive material, and an electrically insulating film deposited and formed on an outer peripheral surface of the tubular base material. A plurality of electrically insulating rims formed by precipitation at intervals along the axial direction; a plurality of thermoelectric conversion elements formed by precipitation in the gap on the outer peripheral surface of the electrically insulating film; A thermoelectric conversion element and a conductive film deposited and formed on the outer peripheral surface of the electrically insulating rim, wherein the thermoelectric conversion element is formed of an n-type semiconductor and a p-type semiconductor that are in contact with the tubular substrate in an axial direction. A concave portion is provided at an interface between the n-type semiconductor and the p-type semiconductor, where the n-type semiconductor and the p-type semiconductor are electrically separated except for one end near the tubular substrate. The thermoelectric conversion device according to claim 1, wherein the thermoelectric conversion device is provided. 3. A plurality of electric substrates formed of an electrically insulating material, and formed on a peripheral surface of the tubular substrate by precipitation molding along an axial direction of the tubular substrate with a gap therebetween. An insulating rim, a plurality of the thermoelectric conversion elements formed in the gap on the outer peripheral surface of the tubular base material, and a conductive material formed on the outer peripheral surface of the thermoelectric conversion element and the electrically insulating rim. A thermoelectric conversion element, wherein the thermoelectric conversion element comprises a bonding pair of an n-type semiconductor and a p-type semiconductor that are in contact with each other in the axial direction of the tubular base material, and at an interface between the n-type semiconductor and the p-type semiconductor, 2. The thermoelectric conversion device according to claim 1, wherein a recess is provided for electrically separating the n-type semiconductor and the p-type semiconductor except for one end near the tubular substrate. 4. The tubular substrate is made of an electrically insulating material, a plurality of grooves provided at intervals along an axial direction on an outer peripheral surface of the tubular substrate, and a plurality of grooves are formed in the grooves. A plurality of the formed thermoelectric conversion elements, and a conductive film deposited and formed on the outer peripheral surfaces of the thermoelectric conversion elements and the groove walls, wherein the thermoelectric conversion elements are arranged in the axial direction of the tubular base material. A junction pair of an n-type semiconductor and a p-type semiconductor that abut on each other, and at the interface between the n-type semiconductor and the p-type semiconductor, the n-type semiconductor and the p-type semiconductor except one end near the tubular substrate. The thermoelectric conversion device according to claim 1, wherein a recess is provided to electrically separate the thermoelectric converter from the thermoelectric converter. 5. A thermoelectric conversion device characterized in that an n-type semiconductor and a p-type semiconductor are deposited and formed on the outer peripheral surface of a tubular substrate by a thermal spraying method to form a thermoelectric conversion element comprising a bonding pair of the semiconductors. Production method. 6. The step of depositing and forming an electrically insulating film on the outer peripheral surface of the tubular substrate, wherein the tubular substrate is made of a conductive material, and the outer peripheral surface of the electrically insulating film is formed by a thermal spraying method. Depositing a plurality of electrically insulative rims at intervals along the axial direction of the tubular base material, and forming the n-type semiconductor and the p-type semiconductor in the gap by thermal spraying. A step of forming a thermoelectric conversion element by sequentially forming the thermoelectric conversion element so that the thermoelectric conversion element is arranged so as to be in contact with the axial direction; and a step of forming a conductive film on the outer peripheral surfaces of the thermoelectric conversion element and the electrically insulating rim by spraying. And providing a recess at the interface between the n-type semiconductor and the p-type semiconductor to electrically separate the n-type semiconductor and the p-type semiconductor except for one end near the tubular substrate. The thermoelectric conversion device according to claim 5, wherein Manufacturing method. 7. The tubular base material is formed of an electrically insulating material, and a plurality of the base materials are formed on the outer peripheral surface of the tubular base material by a thermal spraying method with a gap therebetween along the axial direction of the tubular base material. A step of depositing and forming an electrically insulating rim; and forming a thermoelectric conversion element by successively depositing and forming an n-type semiconductor and a p-type semiconductor in the gap in such a manner that the n-type semiconductor and the p-type semiconductor are arranged side by side in the axial direction of the tubular substrate. Performing a step of depositing and forming a conductive film on the outer peripheral surface of the thermoelectric conversion element and the electrically insulating rim by a thermal spraying method; and forming the tubular substrate at an interface between the n-type semiconductor and the p-type semiconductor. 6. A method of manufacturing a thermoelectric conversion device according to claim 5, further comprising the step of providing a recess for electrically separating the n-type semiconductor and the p-type semiconductor while leaving one end near the material. . 8. The step of providing a plurality of grooves at an interval along an axial direction on an outer peripheral surface of the tubular substrate, wherein the plurality of grooves are formed of an electrically insulating material; Forming a thermoelectric conversion element by sequentially forming an n-type semiconductor and a p-type semiconductor in a line in the axial direction of the tubular substrate by thermal spraying to form a thermoelectric conversion element; and an outer periphery of the thermoelectric conversion element and the groove wall. A step of depositing and forming a conductive film on the surface by a thermal spraying method; and at the interface between the n-type semiconductor and the p-type semiconductor, the n-type semiconductor and the p-type while leaving one end near the tubular substrate. Providing a recess for electrically separating a semiconductor from the semiconductor.