Thermoelectric converter

Abstract

To provide a technique to achieve increase in efficiency of thermoelectric conversion performed by a thermoelectric conversion device and simplification of the device.SOLUTION: A thermoelectric conversion device 1 comprises a first pipe 10, a second pipe 20, and a third pipe 40. The first pipe 10 has a high temperature gas HG circulated therein, and has an area where a contour of a cross section exhibits a polygonal shape, and has thermoelectric elements 30 that are provided in contact with respective polygonal surfaces 12 formed according to the polygonal shape, and elastically deforming separators 23 that are applied with a pressure and adhered to an outer periphery of the thermoelectric elements 30 to surround the thermoelectric elements. An annular closed space 24 defined by the separators 23 and the second pipe 20 is filled with pressed incompressible fluid (high thermal conductive grease TG). An annular space 41 defined by the second pipe 20 and the third pipe 40 is circulated with a cooling medium (water W).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a thermoelectric conversion device.

Background Art

[0002] In recent years, for example, as shown in FIGS. 3 to 4, some thermoelectric conversion devices 1000 circulate a high-temperature medium inside, and have a pipe 100 with an outer diameter of a cross section being polygonal, and a plurality of thermoelectric conversion elements 200 are abutted against a plurality of surfaces 122 constituting the polygon. The outer surface of the thermoelectric conversion element 200 is covered with a heat sink 300, a support ring 400 is arranged outside the heat sink 300, and the heat sink 300 and the thermoelectric conversion element 200 are urged in the axial direction of the pipe 100 by a coil spring 410 attached to the support ring 400 (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor of the present invention has studied a novel structure of a thermoelectric conversion device including a thermoelectric conversion element attached to the outside of a pipe, and has studied to achieve high efficiency of thermoelectric conversion and simplification of the device.

[0005] An object of the present invention is to achieve high efficiency of thermoelectric conversion and simplification of a thermoelectric conversion device.

Means for Solving the Problems

[0006] According to the present invention, the following invention is provided. [1] A thermoelectric conversion device including a first pipe, a second pipe, and a third pipe provided coaxially, The first pipe has a region through which a high-temperature medium flows and whose cross-sectional shape is polygonal. A thermoelectric conversion element is provided in contact with each of the polygonal surfaces formed by the aforementioned polygonal shape, An elastically deformable separator that closely surrounds the outer circumference of the thermoelectric conversion element under pressure, It has, The annular space defined by the separator and the second pipe is filled with pressurized incompressible fluid. A thermoelectric conversion device in which a cooling medium is circulated within an annular space defined by the second pipe and the third pipe. [2] In the space defined by the first pipe and the separator, where the thermoelectric conversion element is not present in the longitudinal direction along the axial line, there is an annular collar whose outer diameter is in contact with the separator and whose inner diameter is not in contact with the outer diameter of the first pipe. The thermoelectric conversion apparatus according to [1], wherein the space defined by the separator and the first pipe is a vacuum. [3] The thermoelectric converter according to [1] or [2], further comprising pressure adjustment means for adjusting the pressure of the incompressible fluid. [4] The thermoelectric conversion device according to any one of [1] to [3], wherein the incompressible fluid is a high thermal conductivity grease. [Effects of the Invention]

[0007] According to the present invention, it is possible to achieve high efficiency in thermoelectric conversion and simplify the apparatus. [Brief explanation of the drawing]

[0008] [Figure 1] This is a longitudinal cross-sectional view of a thermoelectric conversion device according to an embodiment. [Figure 2] This is a cross-sectional view of a thermoelectric conversion device according to an embodiment. [Figure 3] This is a longitudinal cross-sectional view of a conventional thermoelectric conversion device. [Figure 4] This is a cross-sectional view AA in Figure 3. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and their descriptions are omitted as appropriate. Figure 1 is a longitudinal cross-sectional view of the thermoelectric converter 1 according to an embodiment. Figure 2 is a cross-sectional view of the thermoelectric converter 1, and in particular shows the location where the thermoelectric converter element 30 of Figure 1 is installed.

[0010] The thermoelectric converter 1 includes a first pipe 10, a second pipe 20, and a third pipe 40, all of which are mounted coaxially. The first pipe 10 circulates high-temperature gas HG as a high-temperature fluid in its internal space 11. The cross-sectional shape of the first pipe 10 is a regular polygon (in this case, a regular hexagon). That is, 16 planes (hereinafter referred to as "polygonal surfaces 12") are formed on the outer surface (also called the outer surface) of the first pipe 10, arranged in the circumferential direction. These polygonal surfaces 12 are formed in the region where the thermoelectric conversion element 30 is mounted, at least in the longitudinal direction of the axis (left-right direction in the plane of the paper in Figure 1). The outer shape of other parts may be circular (i.e., cylindrical) or polygonal surfaces 12.

[0011] A front plate 21 and a rear plate 22 are attached to two locations along the longitudinal direction of the second pipe 20. Within the space formed by the front plate 21 and the rear plate 22, a thermoelectric conversion element 30 is in contact with the polygonal surface 12. A separator 23 is placed in close contact with the outer circumference of the thermoelectric conversion element 30, surrounding the thermoelectric conversion element 30. The separator 23 has the property of elastically deforming when pressurized. In this embodiment, the thermoelectric conversion elements 30 are shown as being arranged in tandem in the longitudinal direction, but this is not the only configuration, and various arrangements can be adopted.

[0012] An annular collar 33 is disposed at a location in the space formed by the first pipe 10 and the separator 23 where no thermoelectric conversion element 30 exists in the longitudinal direction. The collar 33 is configured such that its outer diameter contacts the separator 23 and its inner diameter does not contact the outer diameter of the first pipe 10. The collar 33 is composed of an end collar 33a that contacts the front plate 21 and the rear plate 22, and a central collar 33b that is disposed between the two thermoelectric conversion elements 30.

[0013] An annular closed space 24 is defined by the second pipe 20 and the separator 23. The annular closed space 24 is filled with a high thermal conductivity grease TG, which is a non-compressible fluid. As the high thermal conductivity grease TG, for example, a material (such as silicone oil) having physical property values such as a thermal conductivity of 2 to 10 W / mK and a viscosity of 50 to 100 Pa·s (25°C) can be used. Also, a pressure adjusting means 25 for adjusting the pressure inside the annular closed space 24 is provided in the annular closed space 24. The pressure adjusting means 25 is composed of a pressurizing portion 25a, a measuring portion 25b, a control portion 25c, and a pipe 25d. The pressurizing portion 25a pressurizes or depressurizes the inside of the annular closed space 24. The measuring portion 25b measures the pressure inside the annular closed space 24. Here, the pressure in the pipe 25d connected to the annular closed space 24 is measured. The control portion 25c controls the pressurizing portion 25a based on the measurement result of the measuring portion 25b to adjust the pressure inside the annular closed space 24. In the present embodiment, the control portion 25c adjusts the pressure inside the annular closed space 24 to be constant. The pipe 25d connects the pressurizing portion 25a and the annular closed space 24.

[0014] A wiring 31 is connected to the thermoelectric conversion element 30. The portion where the wiring 31 passes through the rear plate 22 is kept sealed and insulated by a feed-through 32. The closed space 34 defined by the separator 23 and the first pipe 10 is evacuated to a vacuum (for example, 100 Pa or less).

[0015] A second pipe 20 and a third pipe 40 define an annular space 41, through which water W flows as a cooling medium. The cooling medium may be something other than water W. In this embodiment, a carbon sheet (not shown) is interposed between the contact surface of the polygonal surface 12 and the thermoelectric conversion element 30, and between the contact surface of the thermoelectric conversion element 30 and the separator 23.

[0016] In this embodiment, the first pipe 10, the second pipe 20, the third pipe 40, and the separator 23 are all made of a metal material with high thermal conductivity (for example, copper, iron, or aluminum (including their alloys)). These may be made of the same material or different materials. Stainless steel is preferred for the first pipe 10 from the perspective of preventing oxidation. Copper or aluminum (including their alloys) is preferred for the second pipe 20 from the viewpoint of achieving high thermal conductivity. Furthermore, in this embodiment, a metal foil pipe with a wall thickness of 0.03 to 0.2 mm may be used as the separator 23. For example, a pipe made of stainless steel foil can be used as the metal foil pipe. On the other hand, the front plate 21, rear plate 22, and collar 33 are made of metal or resin materials with low thermal conductivity. These may be made of the same material or different materials.

[0017] Next, we will explain how electricity is generated using the thermoelectric converter 1 of this embodiment. High-temperature gas HG is circulated through the internal space 11 of the first pipe 10, and water W is circulated through the annular space 41 defined by the second pipe 20 and the third pipe 40. The high thermal conductivity grease TG filled in the annular closed space 24 defined by the second pipe 20 and the separator 23 is pressurized to a constant pressure using the pressure adjustment means 25.

[0018] The thermoelectric conversion element 30 becomes hot on its inner surface (i.e., the side facing the first pipe 10) and cold on its outer surface (the side facing the annular space 41). This creates a temperature difference between the inner and outer surfaces of the thermoelectric conversion element 30. As a result, the thermoelectric conversion element 30 generates electricity through thermoelectric conversion. At this time, the thermoelectric conversion element 30 is uniformly pressed toward the axial center by the high thermal conductivity grease TG via the separator 23, and the degree of contact between the thermoelectric conversion element 30 and the polygonal surface 12 of the first pipe 10 is maintained to a high degree, thereby improving the efficiency of thermoelectric conversion.

[0019] An annular collar 33 is placed in the space formed by the first pipe 10 and the separator 23, where there is no thermoelectric conversion element 30 in the longitudinal direction. The collar 33 has an outer diameter that contacts the separator 23, but an inner diameter that does not contact the outer diameter of the first pipe 10. Therefore, even if the separator 23 is pressed toward the axial center by the high thermal conductivity grease TG, the collar 33 will receive the pressure, and the separator 23 will not break. Although an annular collar 33 has been given as an example, it is not limited to this, and various shapes can be used as long as they provide a function to prevent the separator 23 from breaking.

[0020] In the thermoelectric conversion device 1, it is preferable that the parts other than the thermoelectric conversion element 30 are insulated. Here, the collar 33 is made of a metal material with low thermal conductivity, and the closed space 34 defined by the separator 23 and the first pipe 10 becomes a vacuum, achieving high thermal insulation. As a result, the efficiency of thermoelectric conversion in the thermoelectric conversion element 30 is improved.

[0021] Next, we will compare the thermoelectric converter 1 of this embodiment with a conventional thermoelectric converter 1000. 1) Regarding the close contact between the thermoelectric conversion element and the high-temperature heat source. In conventional thermoelectric converters 1000, a support ring 400 is placed on the outside of the heat sink 300, and a coil spring 410 attached to the support ring 400 biases the heat sink 300 and the thermoelectric conversion element 200 toward the axial direction of the piping 100. In other words, in thermoelectric converters 1000, the heat sink 300 acts as a pressing member and presses against the thermoelectric conversion element 200.

[0022] As shown in Figure 4, the heat sink 300 is a long component that extends not only to the thermoelectric conversion elements 200 arranged in tandem along its axial longitudinal direction, but also to the water flow inlet / outlet piping located before and after them.

[0023] Although this heat sink 300 is biased by a coil spring 410, if localized thermal deformation occurs in the components during thermoelectric power generation, it is extremely difficult to flexibly follow this deformation and maintain the degree of contact between the components.

[0024] In contrast, in the thermoelectric conversion device 1 of this embodiment, the thermoelectric conversion element 30 is uniformly pressed (biased) toward the axial center by a highly thermally conductive grease TG, which is an incompressible fluid, via a separator 23, and a high degree of contact is maintained between the parts, namely the thermoelectric conversion element 30 and the polygonal surface 12 of the first pipe 10.

[0025] 2) Regarding the device configuration First, focusing on the pressing structure of the thermoelectric conversion element against the high-temperature heat source, the conventional thermoelectric conversion device 1000 employs a mechanical biasing means and has a very elaborate device configuration, whereas the thermoelectric conversion device 1 of this embodiment employs a biasing means using an incompressible fluid, and the components are arranged in an extremely simple manner. This difference is clear when comparing the drawings of both devices, focusing on the number of components (in particular, the difference is obvious when comparing the drawings of both devices at the same scale).

[0026] Next, focusing on the areas where vacuuming is performed, the thermoelectric converter 1000 is a large-scale device because it configures a pressure vessel to cover the outside of the support ring 400 and vacuums the internal space of this vessel, whereas the thermoelectric converter 1 is extremely simple because it vacuums a very small closed space 34.

[0027] Thus, the thermoelectric conversion device 1 of this embodiment has improved thermoelectric conversion efficiency compared to conventional devices, and the device configuration can be simplified. The embodiments of the present invention have been described above with reference to the drawings, but these are merely examples of the present invention, and various other configurations can also be adopted. [Explanation of Symbols]

[0028] 1. Thermoelectric converter 10. First piping 11 Interior space 12 Polygonal faces 20 Second piping 21 Front panel 22 Rear plate 23 Separator 24 Circular closed space 25 Pressure regulating means 25a Pressurized section 25b Measuring section 25c Control Unit 25d Piping 30 Thermoelectric conversion elements 31 Wiring 32 Feedthrough 33 Colors 33a End color 33b Central Color 34 Closed space 40 Third pipe 41 Circular space HG High Heat Transfer Medium (High Temperature Gas) TG Incompressible Fluid (High Thermal Conductivity Grease) W Cooling medium (water)

Claims

1. A thermoelectric converter comprising a first pipe, a second pipe, and a third pipe provided coaxially, The first pipe has a region through which a high-temperature medium flows and whose cross-sectional shape is polygonal. A thermoelectric conversion element is provided in contact with each of the polygonal surfaces formed by the aforementioned polygonal shape, An elastically deformable separator that closely surrounds the outer circumference of the thermoelectric conversion element under pressure, It has, The annular space defined by the separator and the second pipe is filled with pressurized incompressible fluid. A cooling medium is circulated within the annular space defined by the second pipe and the third pipe. In the space defined by the first pipe and the separator, where the thermoelectric conversion element is not present in the longitudinal direction along the axial line, there is an annular collar whose outer diameter is in contact with the separator and whose inner diameter is not in contact with the outer diameter of the first pipe. A thermoelectric conversion device in which the space defined by the separator and the first pipe is a vacuum.

2. The thermoelectric conversion apparatus according to claim 1, further comprising pressure adjustment means for adjusting the pressure of the incompressible fluid.

3. The thermoelectric conversion apparatus according to claim 1 or 2, wherein the incompressible fluid is a high thermal conductivity grease.

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