JP2017098327A - Laminated thermoelectric conversion module and thermoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated thermoelectric conversion module and a thermoelectric conversion device that are suitable in the case of being installed in various environments having different heat source temperatures.SOLUTION: A laminated thermoelectric conversion module is composed of a plurality of flat thermoelectric conversion modules laminated along a heat transfer direction. Each of the plurality of thermoelectric conversion modules includes a thermoelectric element group configured by collecting and connecting in series a number of structures, each of which is configured by connecting a columnar first thermoelectric element made of a p-type semiconductor with a columnar second thermoelectric element made of an n-type semiconductor in a π shape through a metal electrode. At least one of the plurality of thermoelectric conversion modules is a composite module obtained by combining a plurality of unit modules, the number of which is variable.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a stacked thermoelectric conversion module and a thermoelectric conversion device in which two or more types of thermoelectric conversion modules having different application temperature ranges are stacked.

  Conventionally, a thermoelectric conversion module that directly converts thermal energy into electrical energy or electrical energy into thermal energy using the Seebeck effect or Peltier effect of a thermoelectric conversion element is known. In general thermoelectric conversion modules, a thermoelectric element made of a p-type semiconductor and a thermoelectric element made of an n-type semiconductor are connected in a “π” type via a metal electrode, and a large number of these are assembled and electrically connected in series. A thermoelectric element group, and an insulating substrate (for example, a ceramic substrate) that supports the thermoelectric element group.

  The thermoelectric conversion module has no moving parts (mechanical drive parts) and has a simple structure, so there is no worry about wear deterioration, etc., it is excellent in reliability and durability, easy maintenance, miniaturization and weight reduction. However, there is an advantage that there are few restrictions on the application place. Because of these advantages, it is relatively easy for industrial furnaces (furnace used in melting, refining, and heating processes in various industrial fields such as electric furnaces and combustion furnaces) from which a large amount of heat is discharged. Can be installed. In addition, thermoelectric power generation devices using thermoelectric conversion modules have attracted considerable attention from the viewpoint of environmental conservation and energy saving as a technology that can recover waste heat and reuse it as an energy source without discharging carbon dioxide. Has been.

  In the thermoelectric conversion module, the electric power obtained increases by giving a large temperature difference to the thermoelectric element. However, thermoelectric power generation efficiency of thermoelectric elements depends on temperature, and there is no element material that exhibits excellent power generation characteristics over a wide temperature range.

  Therefore, as a thermoelectric conversion module suitable for performing thermoelectric power generation using a high-temperature heat source of several hundred degrees or more as in an industrial furnace, a laminated thermoelectric module in which two types of thermoelectric conversion modules having different application temperature ranges are laminated. A conversion module has been proposed (for example, Patent Document 1). The applied temperature range is a temperature range in which the expected thermoelectric power generation efficiency can be obtained without deterioration of the thermoelectric element. In the laminated thermoelectric conversion module, it is preferable that each thermoelectric conversion module is given a temperature difference as large as possible within the applicable temperature range.

FIG. 1 is a diagram showing a heat transfer mode in the laminated thermoelectric conversion module M. The thermal resistance R1 of the high-temperature-side thermoelectric conversion module M1 shown in FIG. 1 is proportional to the height d1, and inversely proportional to the cross-sectional area (sum of the cross-sectional areas of the thermoelectric elements) A1. Therefore, the larger the cross-sectional area A1 of the thermoelectric conversion module M1, the smaller the temperature difference ΔT1 (T _H −T _B ) and the larger ΔT2 (T _B −T _C ). Conversely, the smaller the cross-sectional area A1, the greater the temperature difference ΔT1 and the smaller ΔT2. Further, as the height d1 of the thermoelectric conversion module M1 is smaller, the temperature difference ΔT1 is smaller and ΔT2 is larger. Conversely, the greater the height d1, the greater the temperature difference ΔT1 and the smaller ΔT2. The same applies to the cross-sectional area A2 and the height d2 of the thermoelectric conversion module M2 on the low temperature side.

  Thus, by adjusting the cross-sectional areas A1 and A2 or the heights d1 and d2 of the thermoelectric conversion modules M1 and M2, the temperature gradient in the thermoelectric conversion modules M1 and M2 can be adjusted, and the respective thermoelectric conversion modules M1. , M2 can be provided with optimum temperature differences ΔT1 and ΔT2 (see FIG. 9 of Patent Document 1). Thereby, the module performance of the thermoelectric conversion modules M1 and M2 can be maximized.

JP 2013-26334 A

  However, when adjusting the height or cross-sectional area of the thermoelectric conversion module, the thermoelectric conversion module having an appropriate dimension is designed according to the heat source temperature, and the specifications of the thermoelectric module may be diversified, resulting in an increase in manufacturing cost. There is. In particular, when changing the height of the thermoelectric conversion module, it is also necessary to change the housing dimensions of the thermoelectric conversion device.

  An object of the present invention is to provide a laminated thermoelectric conversion module and a thermoelectric conversion device suitable for installation in various environments having different heat source temperatures.

The laminated thermoelectric conversion module according to the present invention is a laminated thermoelectric conversion module in which a plurality of flat thermoelectric conversion modules are laminated along a heat transfer direction,
Each of the plurality of thermoelectric conversion modules connects a columnar first thermoelectric element made of a p-type semiconductor and a columnar second thermoelectric element made of an n-type semiconductor to a π-type via a metal electrode. It has a group of thermoelectric elements that are assembled and electrically connected in series,
At least one of the plurality of thermoelectric conversion modules is a composite module in which a plurality of unit modules are combined, and the number of the unit modules can be changed.

A thermoelectric conversion device according to the present invention includes the above-described laminated thermoelectric conversion module,
A heat receiving plate disposed on a high-temperature side end face of the laminated thermoelectric conversion module and heating the laminated thermoelectric conversion module;
A cooling plate that is disposed on a low-temperature side end face of the laminated thermoelectric conversion module and cools the laminated thermoelectric conversion module;
And a housing for housing the laminated thermoelectric conversion module, the heat receiving plate, and the cooling plate.

  According to the present invention, the temperature gradient formed in the thermoelectric conversion module can be adjusted by adjusting the number of unit modules, and an optimum temperature difference can be given to each thermoelectric conversion module, so the heat source temperature is different. When installing in various environments, it can be easily handled.

It is a figure which shows the heat transfer aspect in a laminated | stacked thermoelectric conversion module. It is a figure which shows the thermoelectric conversion apparatus which concerns on one embodiment of this invention. It is a figure which shows the laminated | stacked thermoelectric conversion module which concerns on embodiment. It is a figure which shows the structure of a unit module. It is a figure which shows the temperature gradient in a laminated | stacked thermoelectric conversion module.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 2 is a diagram showing a thermoelectric conversion device 1 according to an embodiment of the present invention. As shown in FIG. 2, the thermoelectric conversion device 1 includes a stacked thermoelectric conversion module 10, a heat receiving plate 20, a cooling plate 30, and a housing 40. The laminated thermoelectric conversion module 10, the heat receiving plate 20, and the cooling plate 30 are, for example, the back surface of the cooling plate 30 (the surface opposite to the surface that contacts the laminated thermoelectric conversion module 10) while being accommodated in the housing 40. It is fixed by tightening the pressing bolt 50 through the reinforcing beam 60.

  The heat receiving plate 20 is disposed in contact with the high temperature side end surface of the laminated thermoelectric conversion module 10. The heat receiving plate 20 absorbs heat in a furnace in which the thermoelectric conversion device 1 is installed, for example, and heats the laminated thermoelectric conversion module 10. The heating temperature (heat source temperature) varies depending on the environment in which the thermoelectric conversion device 1 is installed.

  The cooling plate 30 is disposed in contact with the low temperature side end face of the laminated thermoelectric conversion module 10. The cooling plate 30 has, for example, a configuration in which a pipe for circulating water is embedded in a metal plate material. By allowing water to flow through the cooling plate 30 at a predetermined flow rate, the low temperature side of the laminated thermoelectric module 10 can be cooled to a predetermined temperature. The cooling temperature is 30 ° C., for example.

  The laminated thermoelectric conversion module 10 is a flat module that can obtain a power generation output using a temperature difference. In the thermoelectric conversion device 1, heat flows into the thermoelectric conversion module 10 from the heat receiving plate 20 and is transmitted toward the cooling plate 30.

  FIG. 3 is a diagram showing the stacked thermoelectric conversion module 10. FIG. 3A is a plan view of the laminated thermoelectric conversion module 10, and FIG. 3B is a cross-sectional view of the thermoelectric conversion module 10. As shown in FIG. 3, the stacked thermoelectric conversion module 10 includes a first thermoelectric conversion module 11 for a high temperature region and a second thermoelectric conversion module 12 for a low temperature region. A metal or carbon soaking plate (not shown) is interposed between the first thermoelectric conversion module 11 and the second thermoelectric conversion module 12.

  The first thermoelectric conversion module 11 is a composite module in which a plurality of unit modules 11S are combined. In the present embodiment, the number of unit modules 11S is 1 to 9, and can be easily changed. The unit module 11S has a square shape in plan view. In FIG. 3, in the first thermoelectric conversion module 11, the unit modules 11 </ b> S are arranged in 2 rows and 2 columns with no gaps, and have a square shape as a whole.

  The second thermoelectric conversion module 12 is a composite module in which a plurality of unit modules 12S are combined. In the present embodiment, the number of unit modules 12S is 1 to 9, and can be easily changed. The unit module 12S has a square shape in plan view. In FIG. 3, in the second thermoelectric conversion module 12, the unit modules 12S are arranged in 3 rows and 3 columns with no gaps, and have a square shape as a whole.

  The area of the unit module 11S constituting the first thermoelectric conversion module 11 and the unit module 12S constituting the second thermoelectric conversion module 12 may be the same or different. The area of the unit modules 11S and 12S is the area of the insulating substrates 104 and 105 (see FIG. 4) constituting the unit modules 11S and 12S. Further, the shape of the unit modules 11S and 12S in plan view is not limited to a square shape, and may be any shape that can be easily combined.

  As shown in FIG. 3, when the module area of the first thermoelectric conversion module 11 is smaller than the module area of the second thermoelectric conversion module 12, the first thermoelectric conversion module 11 has the second thermoelectric module in plan view. It is preferable to be arranged at the approximate center of the conversion module 12. Moreover, when the module area of the 1st thermoelectric conversion module 11 is larger than the module area of the 2nd thermoelectric conversion module 12, the 2nd thermoelectric conversion module 12 is the abbreviation of the 1st thermoelectric conversion module 11 in planar view. It is preferable to arrange in the center. The module area of the first thermoelectric conversion module 11 is the sum of the areas of the unit modules 11S, and the module area of the second thermoelectric conversion module 12 is the sum of the areas of the unit modules 12S.

  FIG. 4 is a diagram showing the unit modules 11S and 12S. As shown in FIG. 4, each of the unit modules 11S and 12S includes a thermoelectric element group 110 and two insulating substrates 104 and 105 that sandwich the thermoelectric element group 110. The thermoelectric element group 110 connects a first thermoelectric element 101 made of a p-type semiconductor and a second thermoelectric element 102 made of an n-type semiconductor to a “π” type through a metal electrode 103, and a large number of these are assembled. And electrically connected in series. Hereinafter, when the first thermoelectric element 101 and the second thermoelectric element 102 are not distinguished, they are expressed as “thermoelectric elements 101 and 102”.

  The thermoelectric elements 101 and 102 are prismatic or columnar members. When the thermoelectric elements 101 and 102 are formed of cylindrical members, resistance to thermal stress is improved.

In the first thermoelectric conversion module 11, the thermoelectric elements 101 and 102 are formed of an oxide compound semiconductor. The first thermoelectric element 101 is formed of a p-type semiconductor substantially made of, for example, Ca ₃ Co ₄ O ₉ . The second thermoelectric element 102 is formed of, for example, an n-type semiconductor substantially made of CaMnO ₃ . In this case, the application temperature range of the first thermoelectric conversion module 11 is 900 ° C. or less.

“Substantially consists of Ca ₃ Co ₄ O ₉ ” means that an optional component other than the essential components Ca, Co and O may be included, and the general formula Ca _a M _b Co ₄ O _c (M : At least one element selected from the group comprising Na, K, Li, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Sr, Ba, Al, Bi, Y and a lanthanoid; 2 ≦ a ≦ 3.6, 0 ≦ b ≦ 0.8, 8 ≦ c ≦ 10).

The phrase “consisting essentially of CaMnO ₃ ” means that an optional component other than the essential components Ca, Mn and O may be included, and the general formula Ca _1-x M ¹ _x Mn _1-y M ² _y O _z (M ¹ : selected from the group comprising Ce, Pr, Nd, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb, Lu, Sr, Ba, Al, Bi, Y and La At least one element, M ² : at least one element selected from the group comprising Ta, Nb, W and Mo, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.2, 2.7 ≦ z ≦ 3 .3).

  In the second thermoelectric conversion module 12, the thermoelectric elements 101 and 102 are formed of a bismuth / tellurium-based semiconductor. In this case, the application temperature range of the second thermoelectric conversion module 11 is 200 ° C. or less. The first thermoelectric element 101 is formed of, for example, p-type BiSbTe in which a part of Bi is replaced with Sb. The second thermoelectric element 102 is made of, for example, n-type BiTeSe in which a part of Te is replaced with Se.

  The metal electrode 103 is made of, for example, Ag. The thermoelectric elements 101 and 102 and the metal electrode 103 are joined by soldering, for example.

  The insulating substrates 104 and 105 are, for example, ceramic substrates. The insulating substrates 104 and 105 may have engagement grooves or engagement pieces for engaging with the adjacent unit modules 11S and 12S. Thereby, the unit modules 11S and 12S can be easily arranged without a gap.

  When the thermoelectric conversion device 1 is installed in the furnace and a temperature difference is applied to each of the first thermoelectric conversion module 11 and the second thermoelectric conversion module 12, an electromotive force is generated. This electric power is taken out through the current leads 106 and 107 of the respective unit modules 11S and 12S. In the first thermoelectric conversion module 11, the current leads 106 and 107 of the adjacent unit modules 11S may be connected. The same applies to the second thermoelectric conversion module 12.

  The number of unit modules 11S constituting the first thermoelectric conversion module 11 and the number of unit modules 12S constituting the second thermoelectric conversion module 12 are set according to the heat source temperature of the environment where the thermoelectric conversion device 1 is installed. The Even if the number of unit modules 11S and 12S is changed, the height of the stacked thermoelectric conversion module 10 is the same, and therefore the dimensions of the housing 40 need not be changed.

  In the present embodiment, the boundary temperature (temperature of the soaking plate) of the joint portion between the first thermoelectric conversion module 11 and the second thermoelectric conversion module 12 is the service temperature of the second thermoelectric conversion module 12 (applicable temperature range). The number of unit modules 11S and 12S is adjusted so as to be 200 ° C., which is the upper limit of the above. For example, when the heat source temperature is 800 ° C., a temperature difference of 600 ° C. is given to the first thermoelectric conversion module 11.

  At this time, of the first thermoelectric conversion module 11 and the second thermoelectric conversion module 12, the number with the higher output performance is set to the maximum (9 in this embodiment), and the number with the lower output performance is set. Is preferably adjusted. In the case of this embodiment, since the output performance of the second thermoelectric conversion module 12 is high, the number of unit modules 11S constituting the first thermoelectric conversion module 11 is adjusted. Thereby, the module performance of the laminated thermoelectric conversion module 10 can be utilized to the maximum extent.

  Thus, the laminated thermoelectric conversion module 10 is a laminated type in which the first thermoelectric conversion module 11 and the second thermoelectric conversion module 12 (a plurality of thermoelectric conversion modules) are laminated along the heat transfer direction. It is a thermoelectric conversion module. The first thermoelectric conversion module 11 and the second thermoelectric conversion module 12 are respectively composed of a columnar first thermoelectric element 101 made of a p-type semiconductor and a columnar second thermoelectric element 102 made of an n-type semiconductor. The thermoelectric element group 110 is connected in a π-type via 103, and a large number of them are assembled and electrically connected in series. The first thermoelectric conversion module 11 and the second thermoelectric conversion module 12 (at least one of the plurality of thermoelectric conversion modules) are composite modules in which a plurality of unit modules 11S and 12S are combined, respectively. The number of 12S can be changed.

  According to the laminated thermoelectric conversion module 10, the temperature gradient formed in the first thermoelectric conversion module 11 and the second thermoelectric conversion module 12 is adjusted by adjusting the number of unit modules 11S and 12S, and the optimum temperature Since a difference can be given, when installing in various environments where heat source temperatures differ, it can respond easily. Further, since the unit modules 11S and 12S having the same design are used, it is not necessary to design a thermoelectric conversion module having a size suitable for each heat source, and it is not necessary to change the size of the housing 40.

[Example]
In the example, a laminated thermoelectric conversion module having the following configuration was manufactured.
First thermoelectric conversion module: Composite module composed of a maximum of nine unit modules First thermoelectric element:
Element material: p-type semiconductor substantially composed of Ca ₃ Co ₄ O ₉ Element size:
Cross-sectional area: 10 to 20 mm ² , height: 4 to 10 mm (rectangular column)
Second thermoelectric element:
Element material: n-type semiconductor made of, for example, CaMnO ₃ Element size:
Cross-sectional area: 10 to 15 mm ² , height: the same as the first thermoelectric element (rectangular column)
Insulating substrate:
Substrate material: Ceramic substrate Substrate size: 60mm x 60mm (square plate)
Element occupation ratio (cross-sectional area of thermoelectric element with respect to area of insulating substrate): 50 to 80%
Applicable temperature range: 900 ° C. or less Second thermoelectric conversion module: Composite module composed of a maximum of nine unit modules First thermoelectric element:
Element material: Bismuth-tellurium p-type semiconductor Element size:
Cross-sectional area: 2-5 mm ² , height: 1-3 mm (cylinder)
Second thermoelectric element:
Device material: Bismuth-tellurium n-type semiconductor Device size:
Cross-sectional area: ^{2 to} 5 mm ² , height: the same as the first thermoelectric element (cylinder)
Insulating substrate:
Substrate material: Ceramic substrate Substrate size: 60mm x 60mm (square plate)
Element occupancy: 30-60%
Applicable temperature range: 200 ° C or less

  FIG. 5A is a diagram illustrating a temperature gradient in the stacked thermoelectric conversion module when there are three unit modules of the first thermoelectric conversion module and nine unit modules of the second thermoelectric conversion module. In this case, the area ratio A1 / A2 between the first thermoelectric conversion module and the second thermoelectric conversion module is 33.3%. As shown in FIG. 5A, when the number of unit modules of the first thermoelectric conversion module is three, the boundary temperature is 180 to 220 (near 200 ° C.) when the heat source temperature is 800 ° C. That is, when the stacked thermoelectric conversion module is installed in an environment where the heat source temperature is 800 ° C., the output performance of the second thermoelectric conversion module can be maximized.

  FIG. 5B is a diagram illustrating a temperature gradient in the stacked thermoelectric conversion module when the number of unit modules of the first thermoelectric conversion module is nine and the number of unit modules of the second thermoelectric conversion module is nine. In this case, the area ratio A1 / A2 of the first thermoelectric conversion module and the second thermoelectric conversion module is 100%. As shown in FIG. 5B, when the number of unit modules of the first thermoelectric conversion module is nine, the boundary temperature is 180 to 220 (near 200 ° C.) when the heat source temperature is 400 ° C. That is, when the stacked thermoelectric conversion module is installed in an environment where the heat source temperature is 400 ° C., the output performance of the second thermoelectric conversion module can be maximized.

  As described above, the laminated thermoelectric conversion module can easily cope with installation in various environments having different heat source temperatures.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and can be changed without departing from the gist thereof.

  For example, in the embodiment, the first thermoelectric conversion module 11 and the second thermoelectric conversion module 12 may be a half skeleton type thermoelectric conversion module in which one of the insulating substrates 104 and 105 is not provided.

  For example, the thermoelectric conversion module which comprises a laminated | stacked thermoelectric conversion module may be three or more layers, and in this case, at least one thermoelectric conversion module should just be a composite module.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion apparatus 10 Stack type thermoelectric conversion module 11 1st thermoelectric conversion module (for high temperature regions)
12 Second thermoelectric conversion module (for low temperature range)
11S, 12S Unit module 101 First thermoelectric element 102 Second thermoelectric element 103 Metal electrode 104, 105 Insulating substrate 106, 107 Current lead 110 Thermoelectric element group 20 Heat receiving plate 30 Cooling plate 40 Housing

Claims (7)

A laminated thermoelectric conversion module in which a plurality of plate-like thermoelectric conversion modules are laminated along a heat transfer direction,
Each of the plurality of thermoelectric conversion modules connects a columnar first thermoelectric element made of a p-type semiconductor and a columnar second thermoelectric element made of an n-type semiconductor to a π-type via a metal electrode. It has a group of thermoelectric elements that are assembled and electrically connected in series,
At least one of the plurality of thermoelectric conversion modules is a composite module obtained by combining a plurality of unit modules, and the number of the unit modules can be changed.   The stacked thermoelectric conversion module according to claim 1, wherein the plurality of thermoelectric conversion modules includes a first thermoelectric conversion module for a high temperature region and a second thermoelectric conversion module for a low temperature region. In the first thermoelectric conversion module, the first thermoelectric element is formed of a p-type semiconductor substantially made of Ca ₃ Co ₄ O ₉ , and the second thermoelectric element is made of CaMnO ₃ substantially Formed of semiconductor,
3. The stacked thermoelectric conversion module according to claim 2, wherein the first thermoelectric element and the second thermoelectric element are formed of a bismuth-tellurium-based semiconductor. In the first thermoelectric conversion module, the occupation ratio of the first thermoelectric element and the second thermoelectric element (the cross-sectional area of the thermoelectric element with respect to the area of the substrate) is 50 to 80%, and the height is 4 to 10 mm. ,
In the second thermoelectric conversion module, the occupation ratio of the first thermoelectric element and the second thermoelectric element is 30 to 60%, and the height is 1 to 3 mm.
A ratio A1 / A2 of the area A1 (total substrate area) of the first thermoelectric conversion module and the area A2 of the second thermoelectric conversion module is 25% to 45%, The laminated thermoelectric conversion module according to claim 3. In the first thermoelectric conversion module, a cross-sectional area of the first thermoelectric element is 10 to 20 mm ² , and a cross-sectional area of the ^second thermoelectric element is 10 to 15 mm ² .
5. The stacked thermoelectric conversion module according to claim 4, wherein the second thermoelectric conversion module has a cross-sectional area of ² to 5 mm ² between the first thermoelectric element and the second thermoelectric element.   The stacked thermoelectric conversion module according to any one of claims 3 to 5, wherein the first thermoelectric conversion module is the composite module. The laminated thermoelectric conversion module according to any one of claims 1 to 6,
A heat receiving plate disposed on a high-temperature side end face of the laminated thermoelectric conversion module and heating the laminated thermoelectric conversion module;
A cooling plate that is disposed on a low-temperature side end face of the laminated thermoelectric conversion module and cools the laminated thermoelectric conversion module;
A thermoelectric conversion device comprising: the stacked thermoelectric conversion module, the heat receiving plate, and a housing that houses the cooling plate.

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