JP2011023581A - Thermoelectric conversion and generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric conversion and generation device, capable of generating high electric power by reducing temperature gradient of a metal heat source and increasing the contact area between the metal heat source and a ceramic substrate to increase a heat-input efficiency from the metal heat source to a thermoelectric conversion module. <P>SOLUTION: The thermoelectric conversion and generation device (1) for generating electric power by arranging the thermoelectric conversion module (4) between the metal heat source (2) and a cooling mechanism (3) and utilizing temperature difference between them, is provided with a heat receiving plate (8) between the metal heat source and the substrate (5) of the thermoelectric conversion module. In addition, the generator (1) may be provided with a layer (10) coated with a heat resistant and electrically conductive coating material on at least one of the surface of the heat receiving plate facing the metal heat source and the surface of the thermoelectric conversion module facing the substrate. Further, a metal layer (11) composed of a heat resistant and electrically conductive metal foil or plate may be provided on the coated layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermoelectric conversion power generation apparatus that generates power from a temperature difference between a high temperature side and a low temperature side using a thermoelectric conversion module, and in particular, reduces distortion of a metal heat source and reduces the contact area between the metal heat source and the thermoelectric conversion module. The present invention relates to a thermoelectric conversion power generation device that can obtain a high power generation output by preventing a decrease.

  Conventionally, a thermoelectric conversion module using the Seebeck effect or the Peltier effect is known, but this thermoelectric conversion module is usually a series of alternating thermoelectric conversion elements made of P-type and N-type semiconductors on a ceramic substrate such as alumina. The p-type and n-type thermoelectric conversion elements are connected by electrodes (see, for example, Patent Documents 1 to 3).

  By the way, when power is generated by a thermoelectric conversion module using a temperature difference between a high temperature side and a low temperature side, an industrial furnace, an incinerator, piping from these, or the like is used as a heat source on the high temperature side. For such a heat source, for example, a heat-resistant metal such as SUS or Inconel is often used. Then, the ceramic substrate of the thermoelectric conversion module is brought into contact with these heat sources to perform heat input. The ceramic substrate of the thermoelectric conversion module is used for the purpose of supporting the thermoelectric conversion element and for electrical insulation from the metal heat source, and is a flat surface.

  FIG. 3 shows a structure of a conventional thermoelectric conversion power generation apparatus using heat from a metal heat source. Conventionally, when power generation is performed using the temperature difference between the high temperature side and the low temperature side, the thermoelectric conversion module 3 1 is brought into contact with the metal heat source 32 as shown in FIG. Heat is input to the thermoelectric conversion module 31 to generate power from a temperature difference generated between the cooling mechanism 33 and the thermoelectric conversion module 31.

  The thermoelectric conversion module 31 includes a ceramic substrate 34, a thermoelectric conversion element 35 in which p-type and n-type semiconductors are alternately arranged in series on the ceramic substrate 34, and p-type and n-type thermoelectric conversion elements, respectively. It consists of an electrode 36 for connection.

  At the beginning of heat input, as shown in FIG. 3A, the metal heat source 32 and the ceramic substrate 34 of the thermoelectric conversion module 31 are in contact with each other without a gap. However, as heat input proceeds, the thermoelectric conversion module 31 is forcibly cooled by the cooling mechanism 33, so that the temperature of the contact surface between the ceramic substrate 34 and the metal heat source 32 also decreases. On the other hand, since heat is continuously supplied from the metal heat source 32, a temperature gradient is generated in the thickness direction of the metal heat source 32.

  As described above, when a temperature gradient is generated inside the metal heat source 32, a thermal stress is generated, and when it exceeds a certain level, plastic deformation is caused. FIG. 3B is a diagram schematically showing a state in which the metal heat source 32 is warped and is recessed with respect to the ceramic substrate 34 as a result of plastic deformation.

  When the metal heat source 32 is recessed with respect to the ceramic substrate 34, a gap g is generated between the metal heat source 32 and the ceramic substrate 34. On the other hand, when the metal heat source 32 is convex with respect to the ceramic substrate 34, the metal heat source 32 presses the ceramic substrate 34 (not shown).

JP-A-5-29667 JP 2005-302783 A JP 2000-164941 A

  As described above, in the conventional thermoelectric conversion power generation device, a temperature gradient is generated in the metal heat source, the metal heat source is warped due to the difference in thermal expansion coefficient between the metal heat source and the ceramic substrate, and the metal heat source is between the metal heat source and the ceramic substrate. In some cases, a gap occurs or a metal heat source presses the ceramic substrate.

  If there is a gap between the metal heat source and the ceramic substrate, the contact area between the metal heat source and the ceramic substrate is significantly reduced, and the heat input from the metal heat source to the thermoelectric conversion module is reduced, resulting in a significant increase in power output. There was a problem of decreasing.

  In addition, when the metal heat source presses the ceramic substrate, the contact area between the metal heat source and the ceramic substrate is also reduced, and pressure is applied to the ceramic substrate. There was also a problem of damage.

  The present invention has been made to solve the above-described problems, reduces the temperature gradient of the metal heat source, reduces the strain applied to the metal heat source, increases the contact area between the metal heat source and the ceramic substrate, It is an object of the present invention to provide a thermoelectric conversion power generator capable of increasing the heat input efficiency from a metal heat source to a thermoelectric conversion module and obtaining a high power generation output.

  In order to achieve this object, the first aspect of the thermoelectric conversion power generator of the present invention uses a temperature difference between the metal heat source and the cooling mechanism by disposing a thermoelectric conversion module between the metal heat source and the cooling mechanism. In the thermoelectric conversion power generation apparatus that obtains the power generation output, a heat receiving plate is disposed between the metal heat source and the substrate of the thermoelectric conversion module.

According to a second aspect of the thermoelectric conversion power generator of the present invention, in the first aspect, the heat receiving plate is selected from silicon carbide (SiC) particles, aluminum nitride (AlN) particles, and silicon nitride (Si ₃ N ₄ ) particles. Further, the present invention is characterized in that it is a cement board containing one kind or several kinds.

  Furthermore, the 3rd aspect of the thermoelectric conversion electric power generating apparatus of this invention is a 2nd aspect. WHEREIN: As for the cement board, the mixture ratio of particle | grains is 85 wt. % Or more.

  According to a fourth aspect of the thermoelectric conversion power generator of the present invention, in the second or third aspect, the particle diameter of the particles is 1 to 3 mm.

  Furthermore, the fifth aspect of the thermoelectric conversion power generator of the present invention is the first to fourth aspects, wherein at least one surface of the heat receiving plate on the metal heat source side or on the substrate side of the thermoelectric conversion module has heat resistance and is conductive. The coating layer which has the coating material which has the property is provided, It is characterized by the above-mentioned.

  Moreover, the 6th aspect of the thermoelectric conversion electric power generating apparatus of this invention is a 5th aspect. WHEREIN: Furthermore, the metal layer which consists of a metal foil or metal plate which has heat resistance further on an application layer is provided. It is characterized by being.

  Furthermore, a seventh aspect of the thermoelectric conversion power generator of the present invention is characterized in that, in the fifth aspect, the coating layer to which the paint having heat resistance and conductivity is applied is made of a silver (Ag) paste. To do.

  The eighth aspect of the thermoelectric conversion power generator of the present invention is characterized in that, in the seventh aspect, the thickness of the coating layer is 0.05 to 1.0 mm.

  Furthermore, the ninth aspect of the thermoelectric conversion power generator of the present invention is characterized in that, in the sixth aspect, the metal layer made of metal foil or metal plate having heat resistance and conductivity is made of silver (Ag). And

  The tenth aspect of the thermoelectric conversion power generator of the present invention is the ninth aspect, wherein the thickness of the metal foil or metal plate having heat resistance and conductivity is 0.02 to 1.0 mm. It is characterized by.

  Furthermore, according to an eleventh aspect of the thermoelectric conversion power generator of the present invention, in the first to tenth aspects, the thermoelectric conversion module is constituted by a thermoelectric conversion element including a p-type oxide semiconductor and an n-type oxide semiconductor. It is characterized by.

  Further, a twelfth aspect of the thermoelectric conversion power generator of the present invention is the eleventh aspect, wherein the oxide-based thermoelectric conversion element comprises a p-type oxide semiconductor, sodium cobalt oxide, calcium cobalt oxide or calcium bismuth. It is one selected from cobalt oxide, and the n-type oxide semiconductor is one selected from zinc oxide, lanthanum nickel oxide, calcium manganese oxide, or strontium titanium oxide.

  According to the thermoelectric conversion power generation device of the present invention, the heat receiving plate having the same thermal expansion coefficient as that of the thermoelectric conversion module substrate is disposed between the metal heat source and the substrate of the thermoelectric conversion module. The thermal stress at the boundary surface of the plate can be reduced, and the heat receiving plate functions as a buffer (thermal resistance layer) for reducing the temperature gradient of the metal heat source, so that the strain applied to the metal heat source can be reduced. For this reason, it becomes difficult to generate | occur | produce a curvature in a metal heat source, and since a contact area required for the heat input from a metal heat source to a thermoelectric conversion module can be ensured, a big electric power output can be obtained.

  Further, a heat-resistant and conductive coating layer is provided on at least one surface of the heat receiving plate, and a heat-resistant and conductive metal foil or a conductive layer is further provided on the coating layer. Since the metal layer made of the metal plate is provided, the contact area between the heat receiving plate necessary for heat input from the metal heat source to the thermoelectric conversion module and the substrate of the thermoelectric conversion module and / or the heat receiving plate and the metal heat source can be further increased. .

It is a side view showing one embodiment of the structure of the thermoelectric conversion power generator of the present invention. It is explanatory drawing of the example which aims at the increase in the contact area in the thermoelectric conversion electric power generating apparatus of this invention. It is a side view which shows the example of the structure of the conventional thermoelectric conversion electric power generating apparatus.

  Hereinafter, preferred embodiments of the thermoelectric conversion power generator of the present invention will be described with reference to the drawings. In addition, in description of each figure after that, the same code | symbol shall be attached | subjected about the same location.

  FIG. 1 is a side view showing an embodiment of the structure of the thermoelectric conversion power generator of the present invention. In FIG. 1, the thermoelectric conversion power generator 1 of the present invention has a thermoelectric conversion module 4 disposed between a metal heat source 2 made of a heat-resistant metal such as SUS or Inconel and a cooling mechanism 3 such as a water-cooled plate. Examples of the metal heat source 2 include piping through which high-temperature gas flows, and power is generated using this heat.

  The thermoelectric conversion module 4 has a ceramic substrate 5 made of alumina or the like, and a thermoelectric conversion element 6 is provided on the ceramic substrate 5. In the thermoelectric conversion element 6, p-type and n-type semiconductor elements are alternately arranged, and the p-type and n-type elements are paired and connected by an electrode 7.

Here, in the present invention, the heat receiving plate 8 is disposed between the metal heat source 2 and the ceramic substrate 5 of the thermoelectric conversion module 4, and the thermoelectric conversion unit 9 is formed together with the thermoelectric conversion module. The heat receiving plate 8 is preferably made of a material having a coefficient of thermal expansion close to that of the ceramic substrate 5, for example, one type of silicon carbide (SiC) particles, aluminum nitride (AlN) particles, or silicon nitride (Si ₃ N ₄ ) particles or A cement board containing several types is suitable. The blending ratio of these particles is preferably high, and 85 wt. % Or more is preferable. 85 wt. If it is less than%, the thermal conductivity is lowered, and the power generation capacity of the thermoelectric conversion power generator is reduced, so that the intended effect of the present invention cannot be obtained.

  The heat receiving plate 8 preferably has a high thermal conductivity in order to increase the heat input efficiency to the thermoelectric conversion module 4. Therefore, the larger the particle diameter, the fewer the grain boundaries, and the smaller the contact resistance between the particles, the higher the thermal conductivity. However, if the particle diameter is too large, the particle density decreases and the strength decreases, so the particle diameter is preferably in the range of 1 to 3 mm.

  Thus, by arranging the heat receiving plate 8, the temperature gradient of the metal heat source 2 is less than that in which the metal heat source 2 and the ceramic substrate 5 of the thermoelectric conversion module 4 are in direct contact, and the occurrence of distortion of the metal heat source 2 is suppressed. . That is, a temperature gradient is generated on the heat receiving plate 8, and the temperature gradient of the metal heat source 2 is greatly reduced. Therefore, distortion is not applied to the metal heat source 2, the contact area for heat input from the metal heat source 2 to the thermoelectric conversion module 4 can be increased, and a high power generation output can be obtained.

  Even if the heat receiving plate 8 has a temperature gradient, the heat receiving plate 8 has a small coefficient of thermal expansion, so that it does not cause distortion that occurs in the metal heat source, so that a contact area necessary for heat input is ensured. be able to. In the thermoelectric conversion unit 9, even when the thermoelectric conversion module 4 is housed in, for example, a metal casing, the metal heat source 2 comes into contact with the metal heat source 2 through the heat receiving plate 8. In addition, there is no distortion that creates a gap.

  Table 1 shows the thermal expansion of SUS310S used as a metal heat source when the temperature is raised from 0 ° C. to 1000 ° C., a cement plate (trade name Carborundum) containing SiC particles used as a heat receiving plate, and an alumina substrate used as a ceramic substrate. It represents the change in rate (%).

  It can be seen that the change in the coefficient of thermal expansion between the heat receiving plate and the ceramic substrate is about 25 to 40% with respect to the change in the coefficient of thermal expansion of the metal heat source, and is hardly affected by the temperature.

  In addition, since the heat receiving plate 8 is a thermal conductor from the high temperature heat source to the substrate of the thermoelectric conversion module and is also a thermal resistor, the effect of increasing the temperature of the surface of the metal heat source that the heat receiving plate contacts by sandwiching the heat receiving plate 8 is effective. Yes, and the heat resistance can be adjusted by changing the thickness of the heat receiving plate, so select an appropriate thickness of the heat receiving plate in consideration of conditions such as the metal heat source thickness, material and heat source temperature. You can also.

  By the way, since the heat receiving plate 8 is made of a material that is not easily affected by temperature as described above, the heat from the metal heat source 2 can be efficiently input to the thermoelectric conversion module 4 with a large contact area. Strictly speaking, many fine irregularities exist on the surface of the heat receiving plate 8. Therefore, even if the heat receiving plate 8 and the ceramic substrate 5 of the thermoelectric conversion module 4 are brought into contact with each other, there are many fine gaps between them. This gap reduces the heat flow and makes the heat flow unstable, and causes a variation in power generation characteristics when commercialized. Therefore, if this gap is filled, the heat receiving plate 8 and the ceramic substrate 5 are further separated. The contact area can be increased, more heat input from the metal heat source 2 can be taken in, and variations in the power generation characteristics of the products can be reduced.

  FIG. 2 is a view showing an example in which the contact area between the heat receiving plate 8 and the ceramic substrate 5 is further increased by smoothing the unevenness of the surface of the heat receiving plate 8 and filling the gap between the heat receiving plate 8 and the ceramic substrate 5. FIG. 2A is an example in which a coating layer 10 to which a heat-resistant and conductive paint is applied is provided in order to fill the unevenness of the surface of the heat receiving plate 8. When the ceramic substrate 5 is brought into contact with the coating layer 10, the space between the heat receiving plate 8 and the ceramic substrate 5 becomes smooth and the contact area increases, so that the heat input efficiency from the metal heat source is improved.

  Silver (Ag) paste is preferable as the paint having heat resistance and conductivity. The Ag paste used here is mixed with an amorphous glass paste that hardens the Ag paste and promotes adhesion to the ceramic substrate in addition to the main component Ag.

  The thickness of the Ag paste as the coating layer 10 should be as thin as possible, and is preferably in the range of 0.05 to 1.0 mm. This is because if the thickness is less than 0.05 mm, it is insufficient to fill the irregularities on the surface of the heat receiving plate 8, and if it exceeds 1.0 mm, the surface of the Ag paste may be cracked.

  FIG. 2B is an example in which a metal layer 11 made of a metal foil or a metal plate having heat resistance and conductivity is further provided on the Ag paste shown in FIG. When the metal layer 11 is further provided on the coating layer 10 in this manner, the space between the heat receiving plate and the ceramic substrate becomes smoother, the contact area is further increased, and the heat input efficiency from the metal heat source 2 is further increased.

  The metal layer 11 is made of a metal foil or a metal plate, and silver (Ag) is preferably selected as the material. The thickness of such an Ag foil or Ag plate is preferably in the range of 0.02 to 1.0 mm. If the thickness is less than 0.02 mm, the Ag paste may not be able to withstand the shrinkage at the time of curing, and the surface may be uneven. If the thickness is greater than 1.0 mm, the contribution to smoothing will be reduced, and thermal resistance will be caused. This is because there is a fear.

  In the embodiment described with reference to FIG. 2, an example in which the coating layer 10 and the metal layer 11 are provided between the heat receiving plate 8 and the ceramic substrate 5 of the thermoelectric conversion module 4 is shown. 10 and the metal layer 11 may be provided between the heat receiving plate 8 and the metal heat source 2. The coating layer 10 or the coating layer 10 and the metal layer 11 may be provided on both surfaces of the heat receiving plate 8.

  2, the coating layer 10 in FIG. 2A, the coating layer 10 in FIG. 2B, and the metal layer 11 are both thermoelectric conversion units together with the ceramic substrate 5 and the thermoelectric conversion element 6. 9 is formed.

Next, the voltage (open voltage) and temperature difference between both ceramic substrates of the thermoelectric conversion module were measured using the thermoelectric conversion power generator of the present invention. Various conditions for the measurement are as follows.
Metal heat source Size of SUS310S hatch door metal heat source (hatch door) attached to a high temperature heat source 120mm x 240mm x 9mm (thickness)
Thermoelectric conversion module 24 vs. alumina substrate module Alumina substrate size 110mm x 220mm x 1mm (thickness)
Thermoelectric conversion element p-type Ca ₃ Co ₄ O _9, n-type LaNiO ₃
Thermoelectric conversion element height 5mm
Cooling mechanism Size of copper water cooling plate cooling mechanism (copper water cooling plate) 120mm x 220mm x 15mm (thickness)
Heat receiving plate Carborundum plate (cement plate containing SiC particles)
Heat receiving plate size 120mm × 220mm × 11mm (thickness)
Under the above conditions, as examples, (1) heat receiving plate only, (2) heat receiving plate + coating layer (Ag paste), (3) heat receiving plate + coating layer (Ag paste) + metal layer (Ag foil, thickness 20 μm) ), (4) Thermoelectric conversion power generation device having a structure of heat receiving plate + coating layer (Ag paste) + metal layer (Ag plate, thickness 300 μm) and a comparative example (1) a conventional structure without a heat receiving plate, (2 ) Open circuit voltage and temperature difference were measured for each thermoelectric conversion power generator having a structure (2 mm) with a thin heat receiving plate. The results are shown in Table 2.

  From the values in Table 2, the open-circuit voltage is small in the thermoelectric conversion power generation device having the conventional structure of Comparative Example 1 in which the heat receiving plate is not provided and the thermoelectric conversion power generation device having the structure of Comparative Example 2 in which the thickness of the heat receiving plate is reduced (2 mm). Moreover, since the temperature difference is small, it can be seen that the power generation output is not sufficient. When the thermoelectric conversion power generation device used in these comparative examples was removed from the metal heat source and observed, distortions that resulted in plastic deformation occurred in the metal heat source, resulting in a gap between the thermoelectric conversion module.

  On the other hand, the thermoelectric conversion power generator of the present invention shows a higher open-circuit voltage and temperature difference than those of Comparative Example 1 and Comparative Example 2 even in the case of only the heat receiving plate having a thickness of 11 mm in Example 1, and the metal heat source It is clear that no distortion occurs and heat input to the thermoelectric conversion module is performed efficiently.

  In addition, Example 2 in which the Ag paste was applied to Example 1 has a larger open-circuit voltage and temperature difference, and it can be seen that a higher effect is obtained by performing smoothing.

  In contrast to Example 2, Example 3 and Example 4 in which an Ag foil or an Ag plate is provided on an Ag paste have a larger open circuit voltage and temperature difference, and smoothing is further promoted. It is clear that the contact area has been increased, and it was shown that a larger power generation output can be obtained by providing the metal layer.

  In addition, a big difference is not seen by Example 3 and Example 4, and a metal layer can show | play the same effect, even if it is a metal foil or a metal plate, and either is suitably selected according to the target thermoelectric conversion electric power generating apparatus. Just choose.

  As described above, since the heat receiving plate is provided between the metal heat source and the thermoelectric conversion module, the thermoelectric conversion power generation device of the present invention has a larger contact area between the metal heat source and the thermoelectric conversion module than the conventional thermoelectric conversion power generation device. Therefore, heat input from the metal heat source to the thermoelectric conversion module is efficiently performed.

  Furthermore, by providing a coating layer coated with a heat-resistant and conductive paint, or by providing a metal layer that also has heat-resistant and conductive properties, smoothing between the metal heat source and the thermoelectric conversion module is achieved. The contact area between the metal heat source and the thermoelectric conversion module can be further increased, higher heat input efficiency can be obtained, and as a result, the power generation output can be significantly improved.

DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion power generator 2 Metal heat source 3 Cooling mechanism 4 Thermoelectric conversion module 5 Ceramic substrate 6 Thermoelectric conversion element 7 Electrode 8 Heat receiving plate 9 Thermoelectric conversion unit 10 Coating layer 11 Metal layer

Claims (12)

  In a thermoelectric conversion power generation device that arranges a thermoelectric conversion module between a metal heat source and a cooling mechanism and obtains a power generation output using a temperature difference between the metal heat source and the cooling mechanism, the metal heat source and the thermoelectric conversion module A thermoelectric conversion power generation device, wherein a heat receiving plate is disposed between the substrate and the substrate. The heat-receiving plate is a cement plate containing one or several kinds selected from silicon carbide (SiC) particles, aluminum nitride (AlN) particles, and silicon nitride (Si ₃ N ₄ ) particles. The thermoelectric conversion power generator as described.   The cement board has a mixing ratio of the particles of 85 wt. The thermoelectric conversion power generator according to claim 2, wherein the thermoelectric conversion power generator is at least%.   The thermoelectric conversion power generator according to claim 2 or 3, wherein a particle diameter of the particles is 1 to 3 mm.   An application layer coated with a paint having heat resistance and conductivity is provided on at least one surface of the heat receiving plate on the metal heat source side or the substrate side of the thermoelectric conversion module. The thermoelectric conversion power generator according to any one of claims 1 to 4.   6. The thermoelectric conversion power generator according to claim 5, further comprising a metal layer made of a metal foil or a metal plate having heat resistance and conductivity on the coating layer.   6. The thermoelectric conversion power generator according to claim 5, wherein the coating layer to which the heat-resistant and conductive coating is applied is made of a silver (Ag) paste.   The thermoelectric conversion power generator according to claim 7, wherein the coating layer has a thickness of 0.05 to 1.0 mm.   The thermoelectric conversion power generator according to claim 6, wherein the metal layer made of metal foil or metal plate having heat resistance and conductivity is made of silver (Ag).   The thermoelectric conversion power generator according to claim 9, wherein the thickness of the metal foil or metal plate is 0.02 to 1.0 mm.   The said thermoelectric conversion module is comprised by the thermoelectric conversion element which consists of a p-type oxide semiconductor and an n-type oxide semiconductor, The claim in any one of Claim 1-10 characterized by the above-mentioned. Thermoelectric conversion power generator. In the oxide thermoelectric conversion element, the p-type oxide semiconductor is one selected from sodium cobalt oxide, calcium cobalt oxide, or calcium bismuth cobalt oxide, and the n-type oxide semiconductor The thermoelectric conversion power generator according to claim 11, wherein is one selected from zinc oxide, lanthanum nickel oxide, calcium manganese oxide, or strontium titanium oxide.

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