JP2006294738A - Tube-like thermoelectric module and thermoelectric convertor using the same, and method of manufacturing thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tube-like thermoelectric module which can be manufactured at a low cost because of its easy-to-assemble, simple and convenient shape, and to provide a thermoelectric convertor using the same and a method of manufacturing of the same. <P>SOLUTION: The tube-like thermoelectric module is provided with a circular p-type thermoelectric conversion element that is provided with an outer peripheral electrode formed on its outer periphery and an inner peripheral electrode formed on its inner periphery, and a circular n-type thermoelectric conversion element that is provided with an outer peripheral electrode formed on its outer periphery and an inner peripheral electrode formed on its inner periphery. The p-type and n-type thermoelectric conversion elements are alternately arranged in the direction of a tube axis, and a conductive tube-like electrode members are arranged among the facing outer peripheral electrodes or the facing inner peripheral electrodes of the adjoining the p-type thermoelectric conversion element and the n-type thermoelectric conversion element. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a thermoelectric power generation module that directly converts heat into electricity, and a tubular thermoelectric module that is particularly useful for a thermoelectric power generation system that uses waste heat generated in a power plant, factory, automobile, etc. as a heat source, and the same. The present invention relates to a method for manufacturing a thermoelectric conversion device and a tubular thermoelectric module.

Thermoelectric materials are materials that can directly convert heat into electricity by the Seebeck effect, and conversely, can convert electricity directly into heat (heating / cooling) by the Peltier effect. As the thermoelectric material, a semiconductor having high conductivity such as metal is used, and usually a combination of p-type and n-type semiconductors is used. This pair is usually called a thermoelectric element, and is generally used as a module in which many elements are combined. This thermoelectric module has advantages such as precise temperature control, local cooling, quietness, no CFC regulation, long life, high reliability, and maintenance-free. It has been used for temperature control of laser diodes for communication.
On the other hand, in recent years, as a global warming problem, there has been a demand for drastic suppression of CO ₂ emissions. Effective use of unused thermal energy in the industrial, consumer, and transportation fields greatly contributes to energy saving and CO ₂ reduction. In order to contribute, development of a thermoelectric module and a thermoelectric conversion device capable of directly converting thermal energy into electric energy has been actively performed.

  As a thermoelectric material used in the low temperature range from room temperature to 200 ° C, BiTe material found by Goldsmid of GE Corporation in the United States in 1954 is generally known, and this material is mostly used for temperature control applications. Is used. Since thermoelectric materials generally have a narrow application temperature range, in power generation applications using waste heat, a thermoelectric material having excellent characteristics in a low temperature range to a medium to high temperature range is required depending on the temperature range. In the low temperature range, the BiTe material used in the previous temperature control application is excellent in characteristics and can be used in power generation applications. Furthermore, BiSb material shows excellent characteristics at lower temperatures. In the middle and high temperature range, ZnSb-based materials, skutterudite materials, oxide materials and the like exhibit excellent characteristics.

Thermoelectric converters generate power using waste heat of low energy density, so it is necessary to install thermoelectric modules in a wide area in order to obtain a certain output, and the manufacturing cost is low. Without it, it is difficult to put it into practical use.
However, in the conventional thermoelectric module, as shown in FIG. 5, it is necessary to arrange a large number of p-type and n-type elements alternately on a plane and to join electrodes so that the elements are electrically in series. Since the manufacturing process is very laborious, the reduction of manufacturing cost has been a big problem. Further, as shown in FIG. 4, a tubular module in which doughnut-shaped P-type and n-type elements are alternately arranged with an insulating material interposed therebetween is also known at the research level. (For example, refer nonpatent literature 1). However, this thermoelectric module is formed of a thermoelectric material by precipitation molding, and it is difficult to say that the thermoelectric module is an effective structure for reducing the manufacturing cost. The complexity of the structure, the manufacturing cost, and the problem that the amount of electricity that can be converted is small have been a major obstacle to the widespread use of thermoelectric conversion devices.

  Although thermoelectric conversion technology is expected to be put into practical use for many years as a technology for recovering unused energy, there is no sign of widespread use. The main reason for this is that the manufacturing cost per output is too high. As a thermoelectric module for power generation, for example, there is a product manufactured by US Hi-Z, but as with the temperature control module, a large number of p-type and n-type elements are alternately joined with electrodes. It has a structure and is very time-consuming to manufacture. In order to use thermoelectric generation technology in the field of heat recovery, solving this problem is the biggest issue.

Therefore, it can be said that a tubular thermoelectric module structure is desirable in view of securing the flow path of the heat source fluid and manufacturing advantages. As a tubular thermoelectric module, for example, Patent Document 1 describes a thermoelectric conversion device formed by depositing a thermoelectric conversion material on the outer peripheral surface of a tubular base material. As shown in FIG. 4, it is disclosed that p-type and n-type thermoelectric conversion materials are alternately arranged along the axial direction and have a joined structure in which both are directly joined at a position from the tubular base material. However, the bonding between the thermoelectric material and the electrode uses a method in which the thermoelectric conversion material and the electrode are formed by thermal spraying, but the thermal spraying is expensive and it is difficult to reduce the manufacturing method. There is a soldering method for joining low cost electrodes and thermoelectric elements, but the melting point of the solder is generally low at 300 degrees or less, and the solder melts when exposed to high temperature above that. There is a problem that it comes off. There is also a method of joining using a high melting point brazing material, but the brazing material generally has a melting point of 700 ° C. or higher, and the melting point of the BiTe material or ZnSb material is about 580 ° C. to 620 ° C. There is a problem that the material melts and cannot be used. The lack of an appropriate brazing material that can be joined between 300 ° C. and 700 ° C. is one of the major issues for using thermoelectric power generation technology in the heat recovery field.
Patent Document 2 describes a thermoelectric generator module having a double cylindrical tube whose inside is a fluid flow path of a high-temperature fluid. This thermoelectric module is provided with a plurality of thermoelectric conversion elements electrically connected in parallel to a gap between the inner tube and the outer tube. However, this is also a question of whether a large number of thermoelectric conversion elements are joined side by side in the circumferential direction of the gap of the double cylindrical tube, so that the connection structure becomes complicated and cost requirements can be satisfied. It is expected to be technically difficult to join such a current.

Japanese Patent No. 3174851 ((0021) to (0025), FIG. 2) Japanese Patent No. 2775410 ((0024), FIG. 5) 18th International Conference on Thermoelectrics P312-315 (1999)

As described above, in the conventional tubular thermoelectric module, although it is tubular, the structure is still complicated, and it has not been possible to solve the cost problem due to complicated manufacturing. In addition, as a low-cost manufacturing method, there is a method of joining a thermoelectric element and an electrode using solder or brazing material. However, when solder is used, a thermoelectric module cannot be used at a temperature higher than the melting point of the solder, and the temperature exceeds 700 ° C. When a high melting point brazing material is used, a low melting point material such as BiTe material cannot be used. Looking at thermoelectric thermoelectric conversion devices, as a heat medium, heat sources such as automobile exhaust gas, heating furnace exhaust gas, and thermal power generation heaters are conventionally used as heat sources. For this reason, the heat resistance and durability of members constituting the apparatus may become a problem.
Therefore, the first object of the present invention is to provide a tubular thermoelectric module that can be manufactured at a low cost by making it easy to assemble, a thermoelectric conversion device using the same, and a method for manufacturing the tubular thermoelectric module. Yes. Furthermore, a second object of the present invention is to provide a tubular thermoelectric module that can be used with high reliability even in a relatively high temperature range, a thermoelectric conversion device using the same, and a method for manufacturing the tubular thermoelectric module.

  One aspect of the present invention is an annular p-type thermoelectric conversion element having an outer peripheral electrode formed on the outer peripheral surface and an inner peripheral electrode formed on the inner peripheral surface, and an outer peripheral electrode and an inner peripheral surface formed on the outer peripheral surface. Annular n-type thermoelectric conversion elements having inner peripheral electrodes formed on the outer peripheral electrodes of the adjacent p-type thermoelectric conversion elements and n-type thermoelectric conversion elements or the inner circumference It is a tubular thermoelectric module in which a tubular electrode member having conductivity is disposed between the surfaces where the electrodes face each other. An annular p-type thermoelectric conversion element having an outer peripheral electrode formed on the outer peripheral surface and an inner peripheral electrode formed on the inner peripheral surface, an outer peripheral electrode formed on the outer peripheral surface, and an inner peripheral electrode formed on the inner peripheral surface By separately providing an annular n-type thermoelectric conversion element having the above and a tubular electrode member having conductivity, a long tubular module can be easily assembled by simply stacking them alternately. By configuring the tubular thermoelectric module as described above, a tubular thermoelectric module having a relatively long length in the tube axis direction can be easily manufactured in a lump, and the tubular thermoelectric modules manufactured individually can be combined and long. Cost can be reduced compared with the case of constituting a tubular thermoelectric module. The electrode member includes a first electrode member positioned between the inner peripheral electrodes and a second electrode member positioned between the outer peripheral electrodes, and the first electrode member and the first electrode member It is preferable if the two electrode members are alternately arranged in the tube axis direction. By setting it as such a structure, the voltage in the case of electric power generation becomes high, and an output can be obtained efficiently.

  It is preferable that a titanium or titanium hydride layer exists at the boundary between the outer peripheral electrode or inner peripheral electrode and the p-type thermoelectric conversion element or n-type thermoelectric conversion element. A heat source of 300 ° C. or higher, which is the melting point of the solder, can be used, and a high-temperature heat source can be used, and a high temperature difference is added to the p-type thermoelectric conversion element and the n-type thermoelectric conversion element to efficiently extract electric power. be able to.

  Furthermore, it is preferable that an annular insulating member is disposed between the opposing surfaces of the p-type thermoelectric conversion element and the n-type thermoelectric conversion element. Furthermore, it is preferable that conductive plating is applied to a joint surface of the outer peripheral electrode or the inner peripheral electrode with the p-type thermoelectric conversion element or the n-type thermoelectric conversion element. This is because this configuration can reduce the electrical loss and further improve the amount of power generation.

  According to one aspect of the present invention, an outer peripheral electrode is bonded to each outer peripheral surface of each of the annular p-type thermoelectric conversion element and the n-type thermoelectric conversion element, and an inner peripheral electrode is bonded to each inner peripheral surface. Between the surfaces where the outer peripheral electrodes or the inner peripheral electrodes of the adjacent p-type thermoelectric conversion elements and n-type thermoelectric conversion elements face each other while alternately arranging the conversion elements and the n-type thermoelectric conversion elements in the tube axis direction An annular electrode member having electrical conductivity is disposed on the tubular thermoelectric module. According to this manufacturing method, the said tubular thermoelectric module can be manufactured suitably. In addition, after applying the solution containing at least titanium hydride to the junction planned surface of the outer peripheral electrode or inner peripheral electrode or the p-type thermoelectric conversion element or n-type thermoelectric conversion element, the outer peripheral electrode or inner peripheral electrode and the p It is preferable to join a type thermoelectric conversion element or an n type thermoelectric conversion element.

Further, in order to increase the reliability of the tubular thermoelectric module, the tubular thermoelectric module has an inner tube disposed inside the inner circumferential electrode and an outer tube disposed outside the outer circumferential electrode, and the outer circumferential surface of the inner tube and It is preferable if a coating layer having electrical insulation is formed on the inner peripheral surface of the outer tube. Further, at least an outer peripheral surface of the inner tube and at least an inner peripheral surface of the outer tube are surfaces for electrically insulating the inner tube and the outer tube from the p-type thermoelectric conversion element and the n-type thermoelectric conversion element. It is preferable to form an insulating coating layer of SiO ₂ or the like.

  One aspect of the present invention is a thermoelectric conversion device using a tubular thermoelectric module provided with the inner tube and the outer tube, wherein the inner tube side is a flow path of a low-temperature fluid, and the outer tube side is a high-temperature side. It is a thermoelectric conversion device characterized by interposing a medium. This thermoelectric conversion device has a flow path through which a high-temperature fluid such as industrial exhaust heat or automobile exhaust gas passes directly or indirectly into the inner tube of the tubular thermoelectric module, and water that has a lower temperature around the outer tube. The medium is interposed to perform thermoelectric conversion. Note that it is effective to increase the surface area of the tubular thermoelectric module by providing fins or the like on the outer surface of the outer tube of the tubular thermoelectric module or the inner surface of the inner tube.

  According to the present invention, the structure is simple, the reliability is high, and the manufacturing cost can be greatly reduced, a heat source higher than 300 ° C. that is the melting point of the solder can be used, and a higher temperature difference can be provided. A tubular thermoelectric module, a thermoelectric conversion device, and a manufacturing method thereof can be provided.

EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.
Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view illustrating a typical configuration of a thermoelectric conversion device 2 in which a tubular thermoelectric module 1 according to an aspect of the present invention is incorporated. The tubular module 1 of this aspect includes an annular p-type thermoelectric conversion element 13 having an outer peripheral electrode 151 formed on the outer peripheral surface and an inner peripheral electrode 152 formed on the inner peripheral surface, and an outer peripheral electrode formed on the outer peripheral surface. 151 and annular n-type thermoelectric conversion elements 14 having inner peripheral electrodes 152 formed on the inner peripheral surface are alternately arranged in the tube axis direction, and the adjacent p-type thermoelectric conversion elements 13 and n-type thermoelectric conversion elements are arranged. 14, the electrode electrodes 191 and 192 having conductivity are disposed between the surfaces of the outer peripheral electrodes 14 and the inner peripheral electrodes facing each other. Here, a layer 18 of titanium or titanium hydride exists at the boundary between the annular electrode and the thermoelectric conversion element. Thus, the thermoelectric module of the present invention is formed by electrically connecting the p-type and n-type thermoelectric conversion elements 13 and 14 in series with the annular electrode members 191 and 192 in the axial direction (length direction) of the tube, In this annular electrode member, a small-diameter annular electrode member 192 positioned on the inner peripheral electrode 152 side and a large-diameter annular electrode member 191 positioned on the outer peripheral electrode 151 side are alternately arranged, and p-type and n-type thermoelectric members are arranged. They are connected so that current flows continuously through the conversion element without loss. As a material of the annular electrode members 191 and 192, copper, SUS304, an aluminum ring, or the like can be used. In the thermoelectric conversion device 2 of this aspect, a metal outer tube 22 is disposed outside the outer peripheral electrode 151 of the tubular thermoelectric module, and a metal inner tube 21 is disposed inside the inner peripheral electrode 152. . That is, the thermoelectric conversion device 2 according to this aspect has a structure in which the thermoelectric conversion module 1 is disposed between a metal inner tube and an outer tube serving as a flow path for a high-temperature fluid. The metal inner tube 21 and the outer tube 22 are coated with an insulating material 23 such as SiO _{2 in} order to electrically insulate the p-type and n-type thermoelectric conversion elements. The p-type and n-type thermoelectric elements 13 and 14 and the electrode members 151 and 152 formed on the inner and outer peripheral portions thereof are provided with a gap between the annular thermoelectric conversion element and the inner and outer electrodes, and mixed with a solvent in the inner and outer gaps. Titanium hydride powder is applied and bonded by hot pressing or discharge sintering at a temperature of 470 ° C. or higher while pressurizing in the tube axis direction with a punch such as SUS304. An annular p-type thermoelectric conversion element 13 having an outer peripheral electrode 151 formed on the outer peripheral surface and an inner peripheral electrode 152 formed on the inner peripheral surface, an outer peripheral electrode 151 formed on the outer peripheral surface, and an inner peripheral surface The annular n-type thermoelectric conversion element 14 having the formed inner peripheral electrode 152 and the annular electrode members 191 and 192 are joined with solder, titanium hydride, or a brazing material interposed therebetween.

(Example 1)
A first embodiment of the present invention will be described.
The raw material powder of Bi-Te thermoelectric material (n-type material) weighs the raw material so that it has a composition of Bi ₂ Te _2.85 Se _0.15 containing 0.1 wt% of SbI ₃ , while the Sb-Te thermoelectric material (p-type material) The raw material powder was synthesized by weighing the raw material so as to have a composition of Bi _0.4 Sb _1.6 Te ₃ and performing mechanical alloying with a vibration mill. The obtained powder (Bi-Te powder or Sb-Te powder) is pressed into a ring shape having an outer diameter of 41.6 mm, an inner diameter of 36.5 mm, and a thickness of 45 mm, and then reduced to 350 ° C. in hydrogen to reduce the oxygen content. After that, the n-type material and the p-type material were both hot-pressed in argon gas at 50 Mpa, 500 ° C. for 1 hour and sintered at an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a thickness of 40 mm. A sintered body was obtained.
Thereafter, a SUS304 pipe having an outer diameter of 44 mm, a thickness of 1 mm, and a length of 45 mm is used for the outer peripheral electrode 152, and a SUS304 pipe having an outer diameter of 36 mm, a thickness of 1 mm, and a length of 45 mm is used for the inner peripheral electrode 151. % Of polyvinyl alcohol was mixed with titanium hydride powder and applied to the inner side of the outer peripheral electrode 152 and the outer side of the inner peripheral electrode 151, and the sintered body was set in the gap between the electrodes. 2 is set on carbon jigs 71 and 73 as shown in FIG. 2 so as to apply pressure only to the sintered body with a punch 72 made of SUS304 having an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a length of 100 mm. Then, the electrode and the thermoelectric element were joined in an argon gas at 570 ° C. for 45 minutes under a pressure of 5 Mpa. The thermoelectric element to which the obtained electrode was bonded was cut to a length of 3 mm. Note that BN spray was sufficiently applied to the punch made of SUS304 to prevent reaction between the punch and the thermoelectric element.

The n-type sintered body (Bi-Te sintered body) 14 in which the outer peripheral electrode 151 and the inner peripheral electrode 152 are formed on the inner and outer peripheries obtained previously, an outer diameter 44 mm × thickness 1 mm × thickness 0. A combination of the first annular electrode member 192 on the large-diameter side of 5 mm and the insulating member 16 made of zirconia, which is an insulating member having an outer diameter of 42 mm, a thickness of 3 mm, and a thickness of 0.5 mm. The p-type sintered body (Sb-Te sintered body) 13 in which the outer peripheral electrode 151 and the inner peripheral electrode 152 are formed on the inner and outer periphery, and the small diameter side of the outer diameter 36 mm × thickness 1 mm × thickness 0.5 mm made of SUS304 A combination of a second annular electrode member 191 and an insulating member 16 made of zirconia having an outer diameter of 44 mm, a thickness of 3 mm, and a thickness of 0.5 mm is set as another set, and these sets are alternately set in ten sets. stacking SUS304 steel inner tube 21 insulated coated on SiO ₂ and outer tube 2 was inserted into the gap portion. In addition, what mixed the titanium hydride 8 in 5 wt% polyvinyl alcohol was apply | coated to both surfaces of the outer peripheral electrode 151 and the inner peripheral electrode 152 of the pipe-axis direction. Thereafter, as shown in FIG. 3, a SUS304 punch 72 was used, and hot uniaxial pressing was performed in argon gas at a temperature of 550 ° C., a pressurizing force of 5 Mpa, and a holding time of 30 minutes to produce a tubular thermoelectric module.

  Next, a 400 ° C. gas was allowed to flow through the inner tube of the thermoelectric conversion device using the tubular thermoelectric module obtained above, and a 20 ° C. cooling water was allowed to flow outside to provide a temperature difference to conduct a power generation test. The maximum output of thermoelectric conversion at this time was obtained by changing the load resistance using an electronic load device. As a result, the obtained output was 15W. Also, no decrease in output was observed in the continuous test for one week.

(Example 2)
A second embodiment of the present invention will be described. The difference from the first embodiment is that the surfaces of the outer peripheral electrode 151 and the inner peripheral electrode 152 are subjected to electroless Ni—P plating in order to increase the reactivity.
The raw material powder of Bi-Te thermoelectric material (n-type material) weighs the raw material so that it has a composition of Bi ₂ Te _2.85 Se _0.15 containing 0.1 wt% of SbI ₃ , while the Sb-Te thermoelectric material (p-type material) The raw material powder was synthesized by weighing the raw material so as to have a composition of Bi _0.4 Sb _1.6 Te ₃ and performing mechanical alloying with a vibration mill. The obtained powder (Bi-Te powder or Sb-Te powder) is pressed into a ring shape having an outer diameter of 41.6 mm, an inner diameter of 36.5 mm, and a thickness of 45 mm, and then reduced to 350 ° C. in hydrogen to reduce the oxygen content. After that, the n-type material and the p-type material were both hot-pressed in argon gas at 50 Mpa, 500 ° C. for 1 hour and sintered at an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a thickness of 40 mm. A sintered body was obtained.

  Thereafter, the outer peripheral electrode 152 is an SUS304 pipe having an outer diameter of 44 mm, a wall thickness of 1 mm, and a length of 45 mm, and the inner electrode 151 is an outer diameter of 36 mm and a wall thickness of 1 mm. Using 45mm long SUS304 tube with electroless Ni-P plating, mix 5wt% polyvinyl alcohol with titanium hydride powder and apply it to the inside of the outer peripheral electrode 152 and the outer side of the inner peripheral electrode 151. And the said sintered compact was set to the space | gap part between the electrodes. 2 is set on carbon jigs 71 and 73 as shown in FIG. 2 so as to apply pressure only to the sintered body with a punch 72 made of SUS304 having an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a length of 100 mm. Then, the electrode and the thermoelectric element were joined in an argon gas at 570 ° C. for 45 minutes under a pressure of 5 Mpa. The thermoelectric element to which the obtained electrode was bonded was cut to a length of 3 mm. Note that BN spray was sufficiently applied to the punch made of SUS304 to prevent reaction between the punch and the thermoelectric element.

The n-type sintered body (Bi-Te sintered body) 14 in which the outer peripheral electrode 151 and the inner peripheral electrode 152 are formed on the inner and outer peripheries obtained previously, an outer diameter 44 mm × thickness 1 mm × thickness 0. A combination of the first annular electrode member 192 on the large-diameter side of 5 mm and the insulating member 16 made of zirconia, which is an insulating member having an outer diameter of 42 mm, a thickness of 3 mm, and a thickness of 0.5 mm. The p-type sintered body (Sb-Te sintered body) 13 in which the outer peripheral electrode 151 and the inner peripheral electrode 152 are formed on the inner and outer periphery, and the small diameter side of the outer diameter 36 mm × thickness 1 mm × thickness 0.5 mm made of SUS304 A combination of a second annular electrode member 191 and an insulating member 16 made of zirconia having an outer diameter of 44 mm, a thickness of 3 mm, and a thickness of 0.5 mm is set as another set, and these sets are alternately set in ten sets. stacking SUS304 steel inner tube 21 insulated coated on SiO ₂ and outer tube 2 was inserted into the gap portion. In addition, what mixed the titanium hydride 8 in 5 wt% polyvinyl alcohol was apply | coated to both surfaces of the pipe-axis direction of the outer periphery electrode 151 and the inner periphery electrode 152. FIG. Thereafter, as shown in FIG. 3, a SUS304 punch 72 was used, and hot uniaxial pressing was performed in argon gas at a temperature of 550 ° C., a pressurizing force of 5 Mpa, and a holding time of 30 minutes to produce a tubular thermoelectric module.
Next, a 400 ° C. gas was allowed to flow through the inner tube of the thermoelectric conversion device using the tubular thermoelectric module obtained above, and a 20 ° C. cooling water was allowed to flow outside to provide a temperature difference to conduct a power generation test. The maximum output of thermoelectric conversion at this time was obtained by changing the load resistance using an electronic load device. As a result, the obtained output was 16W. Also, no decrease in output was observed in the continuous test for one week.

Example 3
A third embodiment of the present invention will be described. The difference from the first embodiment is that the insulating member 16 is not used.
The raw material powder of Bi-Te thermoelectric material (n-type material) is weighed so as to have a composition of Bi ₂ Te _2.85 Se _0.15 containing 0.1 wt% of SbI ₃ , while the Sb-Te thermoelectric material (p-type material) The raw material powder was synthesized by weighing the raw material so as to have a composition of Bi _0.4 Sb _1.6 Te ₃ and performing mechanical alloying with a vibration mill. The obtained powder (Bi-Te powder or Sb-Te powder) is pressed into a ring shape having an outer diameter of 41.6 mm, an inner diameter of 36.5 mm, and a thickness of 45 mm, and then reduced to 350 ° C. in hydrogen to reduce the oxygen content. After that, the n-type material and the p-type material were both hot-pressed in argon gas at 50 Mpa, 500 ° C., sintered for 1 hour with an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a thickness of 40 mm. A sintered body was obtained.

  Thereafter, a SUS304 pipe having an outer diameter of 44 mm, a thickness of 1 mm, and a length of 45 mm is used for the outer peripheral electrode 152, and a SUS304 pipe having an outer diameter of 36 mm, a thickness of 1 mm, and a length of 45 mm is used for the inner peripheral electrode 151. % Of polyvinyl alcohol was mixed with titanium hydride powder and applied to the inner side of the outer peripheral electrode 152 and the outer side of the inner peripheral electrode 151, and the sintered body was set in the gap between the electrodes. 2 is set on carbon jigs 71 and 73 as shown in FIG. 2 so as to apply pressure only to the sintered body with a punch 72 made of SUS304 having an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a length of 100 mm. Then, the electrode and the thermoelectric element were joined in an argon gas at 570 ° C. for 45 minutes under a pressure of 5 Mpa. The thermoelectric element to which the obtained electrode was bonded was cut to a length of 3 mm. Note that BN spray was sufficiently applied to the punch made of SUS304 to prevent reaction between the punch and the thermoelectric element.

The n-type sintered body (Bi-Te sintered body) 14 in which the outer peripheral electrode 151 and the inner peripheral electrode 152 are formed on the inner and outer peripheries obtained previously, an outer diameter 44 mm × thickness 1 mm × thickness 0. A combination of the first annular electrode member 192 on the large-diameter side of 5 mm and the insulating member 16 made of zirconia, which is an insulating member having an outer diameter of 42 mm, a thickness of 3 mm, and a thickness of 0.5 mm. The p-type sintered body (Sb-Te sintered body) 13 in which the outer peripheral electrode 151 and the inner peripheral electrode 152 are formed on the inner and outer periphery, and the small diameter side of the outer diameter 36 mm × thickness 1 mm × thickness 0.5 mm made of SUS304 A combination of a certain second annular electrode member 191 is used as another set, and 10 sets of these sets are alternately stacked in order, and the gap between the inner tube 21 and the outer tube 22 made of SUS304 is insulation-coated with SiO _2. Inserted into the section. In addition, what mixed the titanium hydride 8 in 5 wt% polyvinyl alcohol was apply | coated to both surfaces of the pipe-axis direction of the outer periphery electrode 151 and the inner periphery electrode 152. FIG. Thereafter, as shown in FIG. 3, a SUS304 punch 72 was used, and hot uniaxial pressing was performed in argon gas at a temperature of 550 ° C., a pressurizing force of 5 Mpa, and a holding time of 30 minutes to produce a tubular thermoelectric module.

  Next, a 400 ° C. gas was allowed to flow through the inner tube of the thermoelectric conversion device using the tubular thermoelectric module obtained above, and a 20 ° C. cooling water was allowed to flow outside to provide a temperature difference to conduct a power generation test. The maximum output of thermoelectric conversion at this time was obtained by changing the load resistance using an electronic load device. As a result, the obtained output was 14 W. Also, no decrease in output was observed in the continuous test for one week.

Example 4
A fourth embodiment of the present invention will be described. The difference from the first embodiment is that the inner tube 21 and the outer tube 22 are not used.
The raw material powder of Bi-Te thermoelectric material (n-type material) weighs the raw material so that it has a composition of Bi ₂ Te _2.85 Se _0.15 containing 0.1 wt% of SbI ₃ , while the Sb-Te thermoelectric material (p-type material) The raw material powder was synthesized by weighing the raw material so as to have a composition of Bi _0.4 Sb _1.6 Te ₃ and performing mechanical alloying with a vibration mill. The obtained powder (Bi-Te powder or Sb-Te powder) is pressed into a ring shape having an outer diameter of 41.6 mm, an inner diameter of 36.5 mm, and a thickness of 45 mm, and then reduced to 350 ° C. in hydrogen to reduce the oxygen content. After that, the n-type material and the p-type material were both hot-pressed in argon gas at 50 Mpa, 500 ° C. for 1 hour and sintered at an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a thickness of 40 mm. A sintered body was obtained.

  Thereafter, a SUS304 pipe having an outer diameter of 44 mm, a thickness of 1 mm, and a length of 45 mm is used for the outer peripheral electrode 152, and a SUS304 pipe having an outer diameter of 36 mm, a thickness of 1 mm, and a length of 45 mm is used for the inner peripheral electrode 151. % Of polyvinyl alcohol was mixed with titanium hydride powder and applied to the inner side of the outer peripheral electrode 152 and the outer side of the inner peripheral electrode 151, and the sintered body was set in the gap between the electrodes. 2 is set on carbon jigs 71 and 73 as shown in FIG. 2 so as to apply pressure only to the sintered body with a punch 72 made of SUS304 having an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a length of 100 mm. Then, the electrode and the thermoelectric element were joined in an argon gas at 570 ° C. for 45 minutes under a pressure of 5 Mpa. The thermoelectric element to which the obtained electrode was bonded was cut to a length of 3 mm. Note that BN spray was sufficiently applied to the punch made of SUS304 to prevent reaction between the punch and the thermoelectric element.

  The n-type sintered body (Bi-Te sintered body) 14 in which the outer peripheral electrode 151 and the inner peripheral electrode 152 are formed on the inner and outer peripheries obtained previously, an outer diameter 44 mm × thickness 1 mm × thickness 0. A combination of the first annular electrode member 192 on the large-diameter side of 5 mm and the insulating member 16 made of zirconia, which is an insulating member having an outer diameter of 42 mm, a thickness of 3 mm, and a thickness of 0.5 mm. The p-type sintered body (Sb-Te sintered body) 13 in which the outer peripheral electrode 151 and the inner peripheral electrode 152 are formed on the inner and outer periphery, and the small diameter side of the outer diameter 36 mm × thickness 1 mm × thickness 0.5 mm made of SUS304 A combination of a second annular electrode member 191 and an insulating member 16 made of zirconia having an outer diameter of 44 mm, a thickness of 3 mm, and a thickness of 0.5 mm is set as another set, and these sets are alternately set in ten sets. Stacked up. In addition, what mixed the titanium hydride 8 in 5 wt% polyvinyl alcohol was apply | coated to both surfaces of the outer peripheral electrode 151 and the inner peripheral electrode 152 of the pipe-axis direction. Thereafter, as shown in FIG. 3, a SUS304 punch 72 was used, and hot uniaxial pressing was performed in argon gas at a temperature of 550 ° C., a pressurizing force of 5 Mpa, and a holding time of 30 minutes to produce a tubular thermoelectric module. .

  Next, a 400 ° C. gas was allowed to flow inside the tubular thermoelectric module obtained above, and a 20 ° C. cooling water was allowed to flow outside to provide a temperature difference to conduct a power generation test. The maximum output of thermoelectric conversion at this time was obtained by changing the load resistance using an electronic load device. As a result, the obtained output was 18 W. Also, no decrease in output was observed in the continuous test for one week.

(Example 5)
A fifth embodiment of the present invention will be described. The difference from the first embodiment is that LNG is used instead of the gas at 400 ° C. during output evaluation.
A tubular module was prepared in the same manner as in Example 1, LNG (−160 ° C.) was allowed to flow through the inner tube of the thermoelectric conversion device using the tubular thermoelectric module obtained above, and water at 20 ° C. was poured outside the outer tube. A power generation test was performed with a temperature difference provided by flowing the sample. The difference from Example 1 is that LNG was used as a heat source. The maximum output of thermoelectric conversion at this time was obtained by changing the load resistance using an electronic load device. As a result, the obtained output was 10 W. Also, no decrease in output was observed in the continuous test for one week.

Example 6
A fifth embodiment of the present invention will be described. The difference from the first embodiment is that a skutterudite thermoelectric material is used for the thermoelectric element instead of the BiTe material.
The raw material powder of the skutterudite-based thermoelectric material (n-type material) is weighed so as to have a Yb _0.25 Co ₄ Sb ₁₂ composition, while the raw material powder of the skutterudite-based thermoelectric material (p-type material) is CeFe ₃ CoSb ₁₂ The raw materials were weighed so as to achieve the following composition, and vacuum melting was performed at 1100 ° C. for 24 hours. The obtained alloy was pulverized in an Ar atmosphere to synthesize skutterudite powder. The obtained powder was pressed into a ring shape having an outer diameter of 41.6 mm, an inner diameter of 36.5 mm, and a thickness of 45 mm, and then heat-treated at 350 ° C. for 10 hours in hydrogen to reduce the oxygen content. A sintered body having an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a thickness of 40 mm was obtained by performing discharge plasma sintering in a vacuum at 50 Mpa, 700 ° C. for 30 minutes for both the mold material and the p-type material.

  Thereafter, a SUS304 pipe having an outer diameter of 44 mm, a thickness of 1 mm, and a length of 45 mm is used for the outer peripheral electrode 152, and a SUS304 pipe having an outer diameter of 36 mm, a thickness of 1 mm, and a length of 45 mm is used for the inner peripheral electrode 151. % Of polyvinyl alcohol was mixed with titanium hydride powder and applied to the inner side of the outer peripheral electrode 152 and the outer side of the inner peripheral electrode 151, and the sintered body was set in the gap between the electrodes. 2 is set on carbon jigs 71 and 73 as shown in FIG. 2 so as to apply pressure only to the sintered body with a punch 72 made of SUS304 having an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a length of 100 mm. Then, the electrode and the thermoelectric element were joined in an argon gas at 570 ° C. for 45 minutes under a pressure of 5 Mpa. The thermoelectric element to which the obtained electrode was bonded was cut to a length of 3 mm. Note that BN spray was sufficiently applied to the punch made of SUS304 to prevent reaction between the punch and the thermoelectric element.

An n-type sintered body (skutterudite sintered body) 14 formed with the outer peripheral electrode 151 and the inner peripheral electrode 152 obtained previously, and a large size of SUS304, outer diameter 44 mm × thickness 1 mm × thickness 0.5 mm. A combination of the first annular electrode member 192 on the radial side and the insulating member 16 made of zirconia, which is an insulating member made of zirconia having an outer diameter of 42 mm, a thickness of 3 mm, and a thickness of 0.5 mm, is used as one set. 151 and a p-type sintered body (skutterudite sintered body) 13 on which an inner peripheral electrode 152 is formed, and a second annular ring on the small diameter side of an outer diameter 36 mm × thickness 1 mm × thickness 0.5 mm made of SUS304. A combination of the electrode member 191 and the zirconia outer diameter 44 mm × thickness 3 mm × thickness 0.5 mm of the insulating member 16 is used as another set, and these sets are alternately stacked in order and insulated with SiO ₂ . Coated inner tube made of SUS304 21 and the outer tube 22 were inserted into the gap. In addition, what mixed the titanium hydride 8 in 5 wt% polyvinyl alcohol was apply | coated to both surfaces of the pipe-axis direction of the outer periphery electrode 151 and the inner periphery electrode 152. FIG. Thereafter, as shown in FIG. 3, a SUS304 punch 72 was used, and hot uniaxial pressing was performed in argon gas at a temperature of 550 ° C., a pressurizing force of 5 Mpa, and a holding time of 30 minutes to produce a tubular thermoelectric module.

  Next, a 400 ° C. gas was allowed to flow through the inner tube of the thermoelectric conversion device using the tubular thermoelectric module obtained above, and a 20 ° C. cooling water was allowed to flow outside to provide a temperature difference to conduct a power generation test. The maximum output of thermoelectric conversion at this time was obtained by changing the load resistance using an electronic load device. As a result, the obtained output was 18 W. Also, no decrease in output was observed in the continuous test for one week.

(Comparative Example 1)
Comparative Example 1 will be described. The difference from Example 1 is that solder was used instead of titanium hydride for joining the electrode and the thermoelectric element.
The raw material powder of Bi-Te thermoelectric material (n-type material) weighs the raw material so that it has a composition of Bi ₂ Te _2.85 Se _0.15 containing 0.1 wt% of SbI ₃ , while the Sb-Te thermoelectric material (p-type material) The raw material powder was synthesized by weighing the raw material so as to have a composition of Bi _0.4 Sb _1.6 Te ₃ and performing mechanical alloying with a vibration mill. The obtained powder (Bi-Te powder or Sb-Te powder) was pressed into a ring shape with an outer diameter of 41.6 mm, an inner diameter of 36.5 mm, and a thickness of 45 mm, and then reduced to 350 ° C in hydrogen to reduce the oxygen content. After that, the n-type material and the p-type material were both hot-pressed in argon gas at 50 Mpa, 500 ° C., sintered for 1 hour with an outer diameter of 41.8 mm, an inner diameter of 36.2 mm, and a thickness of 40 mm. After obtaining a sintered body, the surface of the element was subjected to electroless Ni-P plating.

  Thereafter, the outer peripheral electrode 152 is an SUS304 pipe having an outer diameter of 44 mm, a wall thickness of 1 mm, and a length of 45 mm, and the inner electrode 151 is an outer diameter of 36 mm and a wall thickness of 1 mm. Using a 45 mm long SUS304 tube with electroless Ni-P plating, solder paste is applied to the inner side of the outer peripheral electrode 152 and the outer side of the inner peripheral electrode 151, and the above-mentioned firing is applied to the gap between the electrodes. A ligature was set. Then, the electrode and the thermoelectric element were joined in an Ar atmosphere at 300 ° C. for 10 minutes. The thermoelectric element to which the obtained electrode was bonded was cut to a length of 3 mm.

An n-type sintered body (skutterudite sintered body) 14 formed with the outer peripheral electrode 151 and the inner peripheral electrode 152 obtained previously, and a large size of SUS304, outer diameter 44 mm × thickness 1 mm × thickness 0.5 mm. A combination of the first annular electrode member 192 on the radial side and the insulating member 16 made of zirconia, which is an insulating member made of zirconia having an outer diameter of 42 mm, a thickness of 3 mm, and a thickness of 0.5 mm, is used as one set. 151 and a p-type sintered body (skutterudite sintered body) 13 on which an inner peripheral electrode 152 is formed, and a second annular ring on the small diameter side of an outer diameter 36 mm × thickness 1 mm × thickness 0.5 mm made of SUS304. A combination of the electrode member 191 and the zirconia outer diameter 44 mm × thickness 3 mm × thickness 0.5 mm of the insulating member 16 is used as another set, and these sets are alternately stacked in order and insulated with SiO ₂ . Coated inner tube made of SUS304 21 and the outer tube 22 were inserted into the gap. In addition, what mixed the titanium hydride 8 in 5 wt% polyvinyl alcohol was apply | coated to both surfaces of the pipe-axis direction of the outer periphery electrode 151 and the inner periphery electrode 152. FIG. Thereafter, as shown in FIG. 3, a SUS304 punch 72 was used, and hot uniaxial pressing was performed in an argon gas at a temperature of 250 ° C., a pressing force of 5 Mpa, and a holding time of 20 minutes to produce a tubular thermoelectric module.

  Next, a 400 ° C. gas was allowed to flow inside the tubular thermoelectric module obtained above, and a 20 ° C. cooling water was allowed to flow outside to provide a temperature difference to conduct a power generation test. As a result, the solder used for joining melted and the module was damaged.

  As described above, from Examples 1 to 5 and Comparative Example 1, it was found that the tubular thermoelectric module of the present invention can use high-temperature waste heat of 300 ° C. or higher. In addition, components can be manufactured in batches by collecting components into sets, inserting them into these gaps, and then pressing them with hot uniaxial pressing, enabling easy assembly and lower costs. Structure. Moreover, according to Example 2, the effect of Ni plating was confirmed. According to Example 3, it was confirmed that an equivalent output could be obtained without an insulating spacer. In Example 4, it was confirmed that an output could be obtained without using an inner tube and an outer tube. In Example 5, it was confirmed that the output could be obtained even if low temperature LNG was used instead of high temperature. In Example 6, it was confirmed that the output could be obtained not by the BiTe material but also by another skutterudite material.

  INDUSTRIAL APPLICABILITY The present invention can be used for a power generation system using a heat source such as a high-temperature heat source such as waste heat from a factory or an automobile, or LNG vaporization generated in an LNG vaporizer such as an LNG base station or a satellite base.

It is sectional drawing of the pipe-axis direction which shows the structure of the tubular thermoelectric module of this invention. It is sectional drawing explaining the joining method process of the thermoelectric element and electrode of the tubular thermoelectric module of this invention. It is sectional drawing explaining the manufacturing method process of the tubular thermoelectric module of this invention. It is a schematic diagram which shows the structure of the conventional annular thermoelectric module. It is a schematic diagram which shows the structure of the conventional thermoelectric module.

Explanation of symbols

1: tubular thermoelectric module 11: carbon jig 13: p-type thermoelectric conversion element 151: outer peripheral electrode member 152: inner peripheral electrode member 191: first electrode member 192: second electrode member 14: n-type thermoelectric conversion element 16: Insulating member 18: Titanium or titanium hydride layer 2: Thermoelectric converter 21: Inner tube 22: Outer tube 23: Insulating layer 7: Tubular thermoelectric module manufacturing device 71: Carbon die 72: SUS304 punch 73: Carbon split mold 8 : Titanium hydride 9: Tubular module 93 having conventional structure: Outer tube 94: Inner tube 95: Outer electrode 96: Inner electrode 97: Insulating member

Claims (11)

An annular p-type thermoelectric conversion element having an outer peripheral electrode formed on the outer peripheral surface and an inner peripheral electrode formed on the inner peripheral surface, an outer peripheral electrode formed on the outer peripheral surface, and an inner peripheral electrode formed on the inner peripheral surface Of the n-type thermoelectric conversion elements having a plurality of the outer peripheral electrodes of the adjacent p-type thermoelectric conversion elements and the n-type thermoelectric conversion elements or the surfaces of the inner peripheral electrodes facing each other. A tubular thermoelectric module characterized in that an annular electrode member having conductivity is disposed therebetween. The electrode member includes a first electrode member positioned between the inner peripheral electrodes and a second electrode member positioned between the outer peripheral electrodes, and the first electrode member and the second electrode member 2. The tubular thermoelectric module according to claim 1, wherein the electrode members are alternately arranged in the tube axis direction. 3. The tubular according to claim 1, wherein a layer of titanium or titanium hydride exists at a boundary between the outer peripheral electrode or the inner peripheral electrode and the p-type thermoelectric conversion element or the n-type thermoelectric conversion element. Thermoelectric module. The tubular thermoelectric module according to any one of claims 1 to 3, wherein an annular insulating member is disposed between opposing surfaces of the p-type thermoelectric conversion element and the n-type thermoelectric conversion element. . The electroplating is given to the joint surface with the said p-type thermoelectric conversion element or n-type thermoelectric conversion element of the said outer peripheral electrode or an inner peripheral electrode, The Claim 1 thru | or 4 characterized by the above-mentioned. Tubular thermoelectric module. An inner tube disposed on the inner side of the inner peripheral electrode and an outer tube disposed on the outer side of the outer peripheral electrode, wherein the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube are electrically insulated. The tubular thermoelectric module according to claim 1, wherein a covering layer having a property is formed. A thermoelectric conversion device using the tubular thermoelectric module according to claim 6, wherein the inner tube side is a low-temperature fluid flow path and the outer tube side is a medium having a high temperature side. Thermoelectric conversion device. The thermoelectric conversion device according to claim 7, wherein the low-temperature fluid is LNG (liquefied natural gas). The thermoelectric conversion device according to claim 7, wherein the medium is a high-temperature heat source of 300 ° C. or higher. An outer peripheral electrode is joined to the outer peripheral surface of each of the annular p-type thermoelectric conversion element and the n-type thermoelectric conversion element, and an inner peripheral electrode is joined to each inner peripheral surface, and the p-type thermoelectric conversion element and the n-type thermoelectric conversion are joined. The elements are alternately arranged in the tube axis direction, and an annular electrode having conductivity between the outer peripheral electrodes or the inner peripheral electrodes of the adjacent p-type thermoelectric conversion elements and n-type thermoelectric conversion elements facing each other. A method for manufacturing a tubular thermoelectric module, characterized by disposing an electrode member. After applying a solution containing at least titanium hydride to the junction surface of the outer peripheral electrode or inner peripheral electrode or the p-type thermoelectric conversion element or n-type thermoelectric conversion element, the outer peripheral electrode or inner peripheral electrode and the p-type thermoelectric The method for manufacturing a tubular thermoelectric module according to claim 10, wherein the conversion element or the n-type thermoelectric conversion element is joined.