JP2011176131A - Thermoelectric generator and thermoelectric power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric generator and a thermoelectric power generation system, which enhances the transmission efficiency of heat, and also suppresses breakage. <P>SOLUTION: The thermoelectric generator 1 handles a relatively low temperature sphere of 200°C or below as a heat source, and is equipped with: piping 11 in which a medium flows; and a plurality of thermoelectric conversion modules 12 in which two types of electrode faces are coated with a first insulating sheet and a second insulating sheet, respectively. A surface of the second insulating sheet of each of the thermoelectric conversion modules 12 is attached to a surface of the piping 11 via jointing materials 13, and a surface of the piping 11 not provided with each of the thermoelectric conversion modules 12 is coated with a heat insulator 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermoelectric power generation apparatus and a thermoelectric power generation system using a thermoelectric conversion module that converts heat into electricity.

  As one technique for effectively using heat generated in an industrial plant or the like, a technique for generating power using a thermoelectric conversion module has been studied. For example, a plurality of thermoelectric conversion modules are installed between a high-temperature pipe and a low-temperature pipe, high-temperature water generated in an industrial plant or the like is allowed to flow through the high-temperature pipe, low-temperature water is caused to flow into the cold pipe, and power is generated by the temperature difference. It is possible to do it. In addition, as a technique regarding a thermoelectric conversion module, patent documents 1-3 are mentioned, for example.

JP 2008-098403 A JP 2006-165457 A JP 2006-210568 A

  In general, in order to increase the transmission rate between the thermoelectric conversion module and another member, a method of mechanically fastening the thermoelectric conversion module to the member using a bolt or the like, a method of joining with a brazing material, or the like is employed.

  However, the conventional thermoelectric conversion module mounting method is caused by a change in the coefficient of thermal expansion due to repeated thermal cycles, resulting in damage to the thermoelectric conversion module, or due to a single contact caused by variations in the height of a plurality of thermoelectric modules. Therefore, there is a problem that the performance of the thermoelectric conversion module is deteriorated or damaged.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a thermoelectric power generation apparatus and a thermoelectric power generation system capable of improving heat transfer efficiency and suppressing breakage.

  A thermoelectric power generation device according to an aspect of the present invention includes a pipe through which a medium flows, and a plurality of thermoelectric conversion modules in which two types of electrode surfaces are respectively covered with a first insulating plate and a second insulating plate, The surface of the second insulating plate of each thermoelectric conversion module is attached to the surface of the pipe via a bonding material, and the surface of the pipe where each thermoelectric conversion module is not provided is covered with a heat insulating material. It is characterized by that.

  The thermoelectric power generation system according to another aspect of the present invention includes a plurality of the thermoelectric power generation devices, a heat source, and the first insulating plate of each thermoelectric conversion module provided in the plurality of thermoelectric power generation devices. The heat source is disposed so as to receive radiant heat from the heat source.

  According to the present invention, it is possible to improve heat transfer efficiency and suppress breakage.

FIG. 1 is a diagram illustrating a longitudinal cross-sectional shape of the thermoelectric power generation device according to the first embodiment of the present invention, which is cut along a plane along the medium flow direction. FIG. 2 is a view showing a vertical cross-sectional shape when the thermoelectric generator according to the embodiment is cut along a plane perpendicular to the medium flow in the vicinity of the center. FIG. 3 is a diagram showing a detailed cross-sectional shape of the thermoelectric conversion module used in the thermoelectric power generator shown in FIGS. 1 and 2. FIG. 4 is a diagram showing the temperature dependence of the performance of the thermoelectric conversion material. FIG. 5 is a graph showing the power generation performance when the thermoelectric power generation system according to this embodiment is used repeatedly. FIG. 6 is a view showing a longitudinal cross-sectional shape of a thermoelectric power generation system according to the second embodiment of the present invention. FIG. 7 is a diagram of a first state when the thermoelectric power generation system according to the embodiment is viewed from above. FIG. 8 is a diagram of a second state when the thermoelectric power generation system according to the embodiment is viewed from above. FIG. 9 is a diagram illustrating a state in which the distance between the furnace and each thermoelectric power generation device changes in conjunction with the temperature pattern of the furnace.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram illustrating a longitudinal cross-sectional shape of the thermoelectric power generation device according to the first embodiment of the present invention, which is cut along a plane along the medium flow direction. Moreover, FIG. 2 is a figure which shows the longitudinal cross-sectional shape at the time of cut | disconnecting in the surface orthogonal to the flow of a medium in the center vicinity of the thermoelectric generator which concerns on the same embodiment.

  The thermoelectric generator 1 shown in FIGS. 1 and 2 is intended for a relatively low temperature range of 200 ° C. or less as a heat source, and a pipe 11 through which a medium flows and two types of electrode surfaces are not shown. A plurality of thermoelectric conversion modules 12 covered with one insulating plate and a second insulating plate, and the surface of the second insulating plate of each thermoelectric conversion module 12 is connected to the pipe 11 via the bonding material 13. The surface of the pipe 11 attached to the surface and not provided with each thermoelectric conversion module 12 is covered with a heat insulating material 14.

  FIG. 3 is a diagram showing a detailed cross-sectional shape of the thermoelectric conversion module 12 used in the thermoelectric power generator 1 shown in FIGS. 1 and 2.

  As shown in FIG. 3, the thermoelectric conversion module 12 includes a P-type semiconductor element (thermoelectric conversion material) 22 a and a N-type semiconductor element (thermoelectric conversion material) 22 b each having a rectangular parallelepiped or cubic shape with a side of 1 mm or more, for example. The first electrode (conductive material) 20a or the second electrode (conductive material) 20b is connected in series. The first electrode 20a is covered with a first insulating plate (alumina or the like) 21a, and the second electrode 20b is covered with a second insulating plate (alumina or the like) 21b. For example, a solder material is used for joining between the thermoelectric conversion materials (conductive material) and joining the thermoelectric conversion material and the insulating plate. Further, two electrodes at both ends of the series connection structure are provided with electrode outlets 23a and 23b for connecting wirings or lead wires (not shown).

  In the thermoelectric generator 1 having such a configuration, the surface of the first insulating plate 21 a of each thermoelectric conversion module 10 becomes high temperature due to heat from the heat source, and the surface of the second insulating plate 21 b is caused by a medium flowing through the pipe 11. When the temperature becomes low, a temperature difference occurs between both surfaces of each thermoelectric conversion module 10, and thermoelectric conversion occurs in the semiconductor element groups 21 and 22 in the process of heat exchange between both fluids, thereby generating power.

  Hereinafter, the components of the thermoelectric generator 1 will be described in more detail.

  The thermoelectric conversion material used for each thermoelectric conversion module is a material mainly composed of bismuth and tellurium. FIG. 4 shows the temperature dependence of the performance of the thermoelectric conversion material. As shown in FIG. 4, when a relatively low temperature range of 200 ° C. or less is used as a heat source, a Bi-Te material showing a high dimensionless figure of merit is used for the thermoelectric conversion module 10 in this temperature range. It turns out to be desirable. Specific examples of the material include applying (Bi2Te3) 25 (Sb2Te3) 75 to the Te-added p-type material and (Bi2Te3) 90 (Bi2Se3) 10 to the SbI3-added n-type material.

  The medium flowing through the pipe 11 is a liquid or gas made of water, insulating oil, or silicon. In that case, the temperature of the medium is preferably room temperature or less than room temperature in order to increase the temperature difference in the thermoelectric conversion module, and the medium flow rate is preferably 0.1 m / sec or more.

  On the other hand, the material of the piping 11 is steel, stainless steel, copper, an aluminum material, or a metal material whose main component is at least one of them.

  The thermoelectric conversion module 12 is attached to one surface of the pipe 11 through which the medium flows with a bonding material 13. In this case, the necessary number of the thermoelectric conversion modules 12 is appropriately examined according to the amount of power generation to be obtained.

  When joining the thermoelectric conversion module 12 and the pipe 11, it is desirable that the joining surface of the thermoelectric conversion module 12 be roughened by sandblasting or the like. The surface roughness is desirably 80 to 300 μm in terms of ten-point average roughness Rz.

  Further, when joining the thermoelectric conversion module 12 and the pipe 11, it is desirable to metallize the surface (joint surface) of the second insulating plate 21 b of the thermoelectric conversion module in advance and then join the pipe 11 with the joining material 13. Thereby, in the case of joining, joining strength can be raised. In the metallization, a thin film having a thickness of 1 to 10 μm is formed on the surface of the second insulating plate 21b of the thermoelectric conversion module 11 by CVD or PVD using aluminum or copper. Alternatively, a titanium-based paste material may be applied and baked.

  The bonding material 13 includes a low-melting metal having a lower melting point than a material such as a solder material used for each thermoelectric conversion module 11. Specifically, a low melting point metal having a melting point lower by 10 ° C. or more than the melting point of the solder material used for each thermoelectric conversion module 11 is selected. As the low melting point metal, a material mainly composed of bismuth-tin, indium-tin, indium-silver, indium-gallium, indium-bismuth, indium, zu-zinc, and tin-silver is used.

  Further, the bonding material 13 is a paste-like material that is applied and baked on the bonding portion, or a sheet-shaped material made of the bonding material having a thickness of 1 to 20 μm is placed in the bonding portion and melted. It is desirable that the bonding material 13 relieve the stress generated during the thermal cycle.

  Further, the bonding material 13 may be made of a mixed material of a low melting metal and a conductive material. In that case, the conductive material is a material in which fibrous or granular materials mainly composed of carbon are mixed. When the conductive material is mixed with the low-melting metal in this way, heat conduction in the bonding material 13 is increased, and a larger power generation amount can be obtained.

  Furthermore, for the purpose of controlling the movement of heat between the medium in the pipe 11 and the outside, a plurality of thermoelectric conversion modules are attached to one surface of the pipe 11 with a bonding material, and the other exposed portions of the pipe are then insulated. 14, the thickness of the heat insulating material 14 is made smaller than the thickness of the thermoelectric conversion module 12 including the bonding material 13.

  The thermoelectric generator 1 having such a configuration is installed such that the surface of the first insulating plate 21a (see FIG. 3) of each thermoelectric conversion module 10 faces the heat source side. Thereby, the 1st insulating board 21a of each thermoelectric conversion module 10 receives the heat from a heat source, and becomes a high temperature surface. On the other hand, the second insulating plate 21b joined to the surface of the pipe 11 through which the medium flows via the joining material 13 becomes a low temperature surface. Thereby, a temperature difference arises in both surfaces of each thermoelectric conversion module 10, thermoelectric conversion occurs by heat exchange, and electric power generation is performed.

  Although not shown in FIG. 1, by combining the thermoelectric generator 1 with a well-known inverter, controller, power conditioner, battery, capacitor, etc., the generated direct current can be converted into direct current / alternating current. Conversion may be performed to obtain alternating current. Depending on the application, the generated direct current electricity may be used as it is.

  FIG. 5 is a graph showing the power generation performance when the thermoelectric power generation system according to this embodiment is used repeatedly.

  In the graph of FIG. 5, the horizontal axis indicates the number of repetitions (the number of times power generation has been performed), and the vertical axis indicates the power generation performance (= the power generation amount at the time of repeating N times / initial power generation amount). As can be seen from this graph, in the thermoelectric power generation system according to the present embodiment, no significant decrease in power generation performance is observed even after repeating 4000 times, and no thermal load is applied to a plurality of thermoelectric conversion modules. It can be seen that a thermoelectric power generation system with large transmission can be realized. One of the reasons for improving the power generation performance is that the bonding material relaxes the stress generated during the thermal cycle.

  As described above, according to the first embodiment, a thermoelectric power generation device that has high heat transfer efficiency under a heat source atmosphere of 200 ° C. or less and can suppress breakage without mechanically fastening a plurality of thermoelectric modules. Can be realized.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS.

  In the second embodiment, parts that are the same as those in the first embodiment shown in FIG. 2 are given the same reference numerals, and redundant descriptions are omitted. Below, it demonstrates centering on a different part from 1st Embodiment.

  FIG. 6 is a view showing a longitudinal cross-sectional shape of a thermoelectric power generation system according to the second embodiment of the present invention. Moreover, FIG. 7 is a figure of the 1st state which looked at the thermoelectric power generation system which concerns on the same embodiment from upper direction. Moreover, FIG. 8 is a figure of the 2nd state which looked at the thermoelectric power generation system which concerns on the embodiment from upper direction.

  The thermoelectric power generation system shown in FIGS. 6 to 8 includes a plurality of thermoelectric power generation devices 1 described in the first embodiment, a furnace 10 as a heat source, and a drive device that moves the thermoelectric power generation device 1. 30.

  In the present embodiment, the thermoelectric generators 1 are installed in “vertical placement” so that the longitudinal direction of the thermoelectric generators 1 is, for example, the height direction. In that case, the first insulating plate 21a (see FIG. 3) of each thermoelectric conversion module provided in each thermoelectric power generation device faces the furnace 10 so as to receive the radiant heat from the furnace 10 and surrounds the furnace 10. Is done. In addition, you may make it utilize the surplus part of the electric power generated by each thermoelectric power generator 1, for example as a power supply of the drive device 30.

  The drive device 30 can move each thermoelectric generator 1, and the temperature of the thermoelectric conversion module surface of the thermoelectric generation system is based on the temperature detected by a temperature sensor (not shown) installed in each thermoelectric generator 1. The position of each thermoelectric generator 1 is moved so as to maintain an appropriate temperature of 200 ° C. or lower. By this control, the distance between the furnace 10 and each thermoelectric generator 1 is linked to the temperature pattern of the furnace 10 (temperature change with time). For example, as shown in FIG. 6, the distance d from the furnace 10 to the thermoelectric conversion module 12 of each thermoelectric generator 1 is a moderate temperature where the surface temperature of the thermoelectric conversion module 12 facing the furnace 10 is 200 ° C. or less. It adjusts suitably so that it may become temperature.

  Alternatively, the driving device 30 can be moved according to the amount of power generated by each thermoelectric power generation device 1. That is, the amount of power generated by each thermoelectric power generation device is correlated with the temperature of the thermoelectric conversion module surface, and the position of each thermoelectric power generation device 1 is moved so that the temperature of the thermoelectric conversion module surface is maintained at an appropriate temperature of 200 ° C. or less. Let By this control, the distance between the furnace 10 and each thermoelectric generator 1 is linked to the temperature pattern of the furnace 10 (temperature change with time). For example, as shown in FIG. 6, the distance d from the furnace 10 to the thermoelectric conversion module 12 of each thermoelectric generator 1 is a moderate temperature where the surface temperature of the thermoelectric conversion module 12 facing the furnace 10 is 200 ° C. or less. It adjusts suitably so that it may become temperature.

  Here, an example in which the distance between the furnace 10 and each thermoelectric generator 1 changes in conjunction with the temperature pattern of the furnace 10 will be described with reference to FIGS. 6 to 8 and FIG. 9.

  For example, when the temperature of the furnace 10 is still low during the temperature rising process of the furnace 10, each thermoelectric generator 1 is in the vicinity of the furnace 10. At this time, as shown in FIG. 7, the distance from the furnace 10 to the thermoelectric conversion module 12 of each thermoelectric generator 1 is, for example, d1. As the temperature of the furnace 10 increases, the driving device 30 moves each thermoelectric power generation apparatus 1 away from the furnace 10. As a result, as shown in FIG. 8, the distance from the furnace 10 to the thermoelectric conversion module 12 of each thermoelectric generator 1 is d2, which is larger than d1, for example. Further, in the temperature lowering process of the furnace 10, the drive device 30 moves each thermoelectric generator 1 so as to approach the furnace 10.

  6 to 8 show an example in which six thermoelectric generators 1 are used, the present invention is not limited to this, and more thermoelectric generators 1 may be provided. Moreover, although the example which installs each thermoelectric power generation apparatus 1 in "vertical installation" was shown in FIG. 6 thru | or FIG. 8, it is not limited to this but the longitudinal direction of each thermoelectric power generation apparatus 1 becomes a horizontal direction. It may be installed in “horizontal”. In that case, a plurality of “horizontal placement” thermoelectric generators 1 may be stacked.

  As described above, according to the second embodiment, in addition to the effects of the first embodiment described above, the plurality of thermoelectric generators 1 are arranged to receive the radiant heat from the furnace 10 at an appropriate temperature of 200 ° C. or less.・ Because it is controlled, the power generation efficiency can be further improved.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Thermoelectric power generation device, 10 ... Furnace, 11 ... Piping, 12 ... Thermoelectric conversion module, 13 ... Bonding material, 14 ... Heat insulating material, 20a ... 1st electrode (conductive material), 20b ... 2nd electrode (conductive material) ), 21a... 1st insulating plate, 21b... 2nd insulating plate, 22a... P-type semiconductor element (thermoelectric conversion material), 22b... N-type semiconductor element (thermoelectric conversion material), 23a and 23b.

Claims (10)

  A pipe through which a medium flows, and a plurality of thermoelectric conversion modules each having two types of electrode surfaces covered with a first insulating plate and a second insulating plate, and the second insulating plate of each thermoelectric conversion module The thermoelectric power generator is characterized in that the surface of the pipe is attached to the surface of the pipe via a bonding material, and the surface of the pipe not provided with each thermoelectric conversion module is covered with a heat insulating material.   The thermoelectric power generation apparatus according to claim 1, wherein the thermoelectric conversion material used for each thermoelectric conversion module is a material mainly composed of bismuth and tellurium.   The thermoelectric power generator according to claim 1 or 2, wherein the medium flowing through the pipe is a liquid or gas made of water, insulating oil, or silicon.   The thermoelectric power generation according to any one of claims 1 to 3, wherein the material of the pipe is steel, stainless steel, copper, aluminum material, or a metal material containing at least one of them as a main component. apparatus.   The thermoelectric power generator according to any one of claims 1 to 4, wherein a surface of the second insulating plate of each thermoelectric conversion module forms a rough surface.   The thermoelectric generator according to any one of claims 1 to 5, wherein a surface of the second insulating plate of each thermoelectric conversion module is metallized.   The thermoelectric generator according to any one of claims 1 to 6, wherein the bonding material includes a metal having a melting point lower than that of a material used for each thermoelectric conversion module.   The thermoelectric generator according to claim 7, wherein the bonding material is made of a mixed material of the low-melting metal and a conductive material.   The thermoelectric generator according to claim 8, wherein the conductive material includes a fibrous or granular material containing carbon as a main component. A plurality of the thermoelectric generators according to any one of claims 1 to 9, and a heat source,
The thermoelectric power generation system, wherein the first insulating plate of each thermoelectric conversion module provided in the plurality of thermoelectric power generation devices is disposed so as to surround the heat source so as to receive radiant heat from the heat source.

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