JP2022043666A - Thermoelectric conversion device - Google Patents

Abstract

To provide a thermoelectric conversion device that can prevent the outflow of fluid due to the pressure difference between the inside and outside of the equipment due to the installation of the thermoelectric conversion module, easily collect heat from the fluid of the heat source, and further reduce the heat loss.SOLUTION: A thermoelectric conversion device includes: a thermoelectric conversion module 10; a heat receiving member 30 having a flat surface portion and a fin portion erected on one surface of the flat surface portion, and having the other surface of the flat surface portion closely arranged on one side of the thermoelectric conversion module; a cooling member 20 placed in close contact with the other side of the thermoelectric conversion module; a tubular outer shell member 40 arranged so as to surround the heat receiving member, the thermoelectric conversion module, and the cooling member; a first jig 50 that supports an end of the flat surface of the heat receiving member by sandwiching the end of the flat surface with the outer shell member; a second jig 60 that supports the thermoelectric conversion module by sandwiching the cooling member; and a sealing member 70 arranged between the flat surface portion of the heat receiving member and the outer shell member.SELECTED DRAWING: Figure 9

Description

The present invention relates to a thermoelectric conversion device using a thermoelectric conversion module that directly converts heat into electricity.

In recent years, in order to reduce energy consumption, it has been studied to recover waste heat from, for example, a boiler, an incinerator, or a heat source of an automobile as electricity. In particular, a thermoelectric conversion module that can efficiently recover electric energy by using a thermoelectric element that can directly convert thermal energy into electric energy by the Zeebeck effect is attracting attention. A thermoelectric module is one in which P-type and N-type thermoelectric conversion elements are alternately connected via electrodes. One surface is on the high temperature side and the other surface is on the low temperature side, causing a temperature difference on both sides. It generates electric power. It is expected to be put into practical use as a clean method that can effectively utilize the waste heat that has been discarded until now. In particular, by using a thermoelectric conversion element made of a material that can be used in a high temperature environment of about 300 ° C. or higher, there is a possibility that a large electric energy can be recovered from a large temperature difference, and therefore development is underway.

In order to give a large temperature difference to the thermoelectric conversion module using a fluid such as high temperature gas, heat from the fluid is transferred to the high temperature side without loss, and heat transfer from other than the thermoelectric conversion element to the low temperature side is reduced. It is important to increase the temperature difference between the high temperature side and the low temperature side.

For example, Patent Document 1 discloses a thermoelectric conversion power generation unit that grips a thermoelectric conversion module between a heat receiving member and a cooling member. Further, there is disclosed a configuration in which the thermoelectric conversion power generation unit has a heating unit and a cooling unit, and is provided in a tunnel type furnace in which a heated body is sequentially conveyed inside the heating unit and the cooling unit.

Further, in Patent Document 2, one surface of the thermoelectric conversion module is arranged on a heat receiving plate attached to the opening of the furnace, and the other surface of the thermoelectric conversion module is closely attached to and fixed to the water cooling plate and attached. , A thermoelectric conversion device having heat receiving fins formed on the heat receiving side in the furnace is disclosed.

Japanese Unexamined Patent Publication No. 2004-350479 Japanese Unexamined Patent Publication No. 2013-211471

In Patent Document 1, since the heat receiving member and the cooling member grip each other, there is a problem that heat is conducted from the heat receiving member to the cooling member and is easily lost. Further, there is a problem that heat loss is likely to occur in the heating part and the cooling part of the tunnel furnace, and it is difficult to obtain a large temperature difference in the thermoelectric conversion module.

In Patent Document 2, it is conceivable that the heat receiving plate is in contact with the case, and the heat collected by the heat receiving plate is transmitted inside the member of the case to reduce the temperature difference from the water cooling plate. Furthermore, if the pressure of the high temperature gas on the heat receiving side is higher than that outside the furnace, it is possible that a gap may occur between the case and the heat receiving plate.

An object of the present invention is to prevent the outflow of fluid due to the pressure difference between the inside and outside of the equipment due to the attachment of the thermoelectric conversion module, to easily collect heat from the fluid of the heat source, and to further reduce the heat loss. It is to provide a conversion device.

The thermoelectric conversion device of the present invention includes a thermoelectric conversion module and
A heat receiving member having a flat surface portion and fin portions erected on one surface of the flat surface portion, and having the other surface of the flat surface portion closely arranged on one side of the thermoelectric conversion module.
A cooling member arranged in close contact with the other side of the thermoelectric conversion module, and
A tubular outer shell member arranged so as to surround the heat receiving member, the thermoelectric conversion module, and the cooling member.
A first jig that supports the end of the flat surface portion of the heat receiving member by sandwiching it between the outer shell member and the outer shell member.
A second jig that supports the thermoelectric conversion module by sandwiching the cooling member, and
A sealing member arranged between the flat surface portion of the heat receiving member and the outer shell member, and
It is characterized by having.

Further, it is preferable that the outer shell member has a groove at a position where the sealing member is arranged.

Further, it is preferable that the first jig is not in contact with the second jig.

Further, the first jig includes a holding portion that supports the end of the flat surface portion of the heat receiving member by sandwiching the outer shell member via the sealing member, and a pillar portion that supports the holding portion. It is preferable to have.

Further, it is preferable that the fin portion and a part of the outer shell member project to the heat source fluid.

According to the present invention, in the thermoelectric conversion device, the outflow of fluid due to the pressure difference between the inside and outside of the equipment due to the attachment of the thermoelectric conversion module is prevented, and heat can be easily collected from the fluid (high temperature fluid) of the heat source, and the heat can be further increased. The loss can be reduced.

Schematic diagram of the appearance of the thermoelectric conversion module A perspective view showing a cooling member integrated with a thermoelectric conversion module. External view of heat receiving member Cross-sectional perspective view of the outer shell member Assembly sectional view of thermoelectric converter Example of mounting piping External view of the first jig External view of the second jig Sectional view of thermoelectric converter Graph showing the relationship between the gas temperature and the temperature of each part

An embodiment of the thermoelectric conversion device of the present invention will be described below. The embodiment of the thermoelectric conversion device of the present invention is
Thermoelectric conversion module and
A heat receiving member having a flat surface portion and fin portions erected on one surface of the flat surface portion, and having the other surface of the flat surface portion closely arranged on one side of the thermoelectric conversion module.
A cooling member arranged in close contact with the other side of the thermoelectric conversion module, and
A tubular outer shell member arranged so as to surround the heat receiving member, the thermoelectric conversion module, and the cooling member.
A first jig that supports the end of the flat surface portion of the heat receiving member by sandwiching it between the outer shell member and the outer shell member.
A second jig that supports the thermoelectric conversion module by sandwiching the cooling member, and
A sealing member arranged between the flat surface portion of the heat receiving member and the outer shell member, and
have. Each configuration will be described below.

(Thermoelectric conversion module)
Figure 1 schematically shows the appearance of the thermoelectric conversion module. A P-type and N-type thermoelectric conversion element connected via electrodes, with one side on the high temperature side and the other side on the low temperature side, and power conversion is performed by creating a temperature difference on both sides. Is. At this time, in the N-type device, electrons with high density on the high temperature side flow to the low temperature side, and in the P-type device, holes having a positive charge on the low temperature side flow to the high temperature side, and the opposite potential difference. Causes a current to flow. The phenomenon in which thermoelectromotive force is generated by the temperature difference is called the Zeebeck effect.

In FIG. 1, as an example thereof, a P-type element 11, an N-type element 12, a high temperature side electrode 13, a low temperature side electrode 14, an insulating substrate 15, and an electrode termination 16 are shown. Further, in order to show the arrangement state of the elements and electrodes, the insulating substrate 15 is shown in a state where the breaking line is removed as a boundary. A pair is made by connecting P-type and N-type with electrodes. The amount of power generated in a pair is extremely small, about 1 to 100 mA, depending on the temperature difference, but it is preferable to connect a plurality of them because a large amount of power can be obtained. In addition, although the voltage of a pair is low, the voltage may be increased by arranging them in series electrically, and even if a voltage value that can be used for commercial products is obtained by boosting with a DC-DC converter for boosting. good.

As the thermoelectric conversion element, it is preferable to use a material such as Mg ₂ Si-based, silicide-based, half-Whisler-based, and scutterdite-based material for high temperatures of 300 ° C. or higher. Since these materials may oxidize when exposed to the atmosphere in a high temperature region, it is preferable to suppress the oxidation by, for example, sealing in a vacuum atmosphere, that is, vacuum sealing. The vacuum sealing may be performed by surrounding only the region near the outer periphery of the thermoelectric conversion module, or may be sealed integrally with the cooling member to which the low temperature surface of the thermoelectric conversion module is in close contact.

(Cooling member)
The cooling member is used to cool the low temperature side of the thermoelectric conversion module. The cooling member has one or more planes and is cooled by a cooling medium (refrigerant). By bringing the flat surface of this cooling member into close contact with the surface on the low temperature side of the thermoelectric conversion module, the surface on the low temperature side of the thermoelectric conversion module is cooled. An example of the case where the cooling member and the thermoelectric conversion module are integrated will be described below. Figure 2 shows a schematic disassembled view of a part of the thermoelectric conversion device integrated with the thermoelectric conversion module. The thermoelectric conversion module 10, the cooling member 20, the cap 22, the refrigerant pipe 23, and the terminal 24, respectively. The cooling member 20 may be a water cooling plate or the like, and as described above, if it has a surface for cooling the low temperature side of the thermoelectric conversion module, it has a water channel structure on the opposite side of the main surface in addition to the plate shape. It may have a shape having a body.

Hereinafter, a cooling member when water is used as the refrigerant will be described as an example. In this case, the refrigerant pipe may be read as a water pipe, a water hose, or a water tube. The cooling member has a size that allows it to fit into the outer shell member described later with a margin. This makes it possible to maintain a gap inside the outer shell member and arrange the cooling member. The shape may be any shape as long as it has a flat surface wider than the thermoelectric conversion module so that all the low temperature surfaces of the thermoelectric conversion module can be in close contact with each other, and the contact surface has a wall thickness sufficiently cooled by the cooling medium.
Aluminum, copper, and stainless steel are generally used as the material of the cooling member, and copper is preferable from the viewpoint of high thermal conductivity, and nickel plating is more preferable to prevent oxidation.
The cooling member 20 in FIG. 2 is a diagram in which the cooling member has a cylindrical shape and is provided with a refrigerant pipe 23 that serves as an inlet / outlet for water. The low temperature surface of the thermoelectric conversion module 10 is brought into close contact with one side of the cylinder, covered with a cap 22, and the outer circumference of the cap 22 is welded to the cooling member 20 in a vacuum atmosphere to vacuum-seal the thermoelectric conversion module. The cap 22 is large enough to completely cover the thermoelectric conversion module and has a shape with a brim attached to the container. Stainless steel or the like is preferable as a material having heat resistance and oxidation resistance that does not cause any problem even if it comes into contact with a heat receiving member for a long time and has strength to maintain vacuum sealing. Further, in order to transfer the heat received from the heat receiving member to the high temperature surface of the thermoelectric conversion module 10 with low loss, it is desirable to make the wall thickness as thin as possible.
The terminal 24 is used when the current generated by the thermoelectric conversion module is taken out of the vacuum-sealed space. As the terminal 24, for example, one conducting wire may be provided with a welding material on the outer periphery thereof via an insulating material such as ceramics or glass. Copper, stainless steel, nickel, Fe-Ni-Co alloy, etc. are often used as the material of the conductor and the joint. When taking out the current, for example, if the current is taken out in the XY direction, a small terminal may be used. It is preferable to take out the current away from the heating source in order to prevent the current from leaking by contacting the adjacent heat receiving member and to prevent the insulating member from touching the heat receiving member and escaping the heat. For example, the terminals may be arranged in the direction toward the cooling member. In this case, specifically, the terminal is welded to the cooling member so as not to interfere with the flow path of the cooling medium, and the tip of the terminal is joined to the terminal 16 of the electrode of the thermoelectric conversion module, so that the generated power is transferred to the atmosphere. It is conceivable to take it out.
When the thermoelectric conversion module is sandwiched between the cooling member and the cap in the z direction, it is preferable to sandwich the ceramic substrate between the cap and the thermoelectric conversion module to maintain insulation, and further to sandwich the graphite sheet to improve the adhesion.

(Heat receiving member)
Figure 3 shows the appearance of the heat receiving member. In the example of FIG. 3, the fin portion 32 of the heat receiving member is erected vertically (in the z direction) on one surface of the flat plate-shaped flat surface portion 31. Here, the flat surface portion may have a flat surface for transferring heat to the high temperature portion of the thermoelectric conversion module. For example, it may have a flat plate shape as shown in FIG. 3, and may have a structure such as a slight change in thickness and a groove for forming a fin portion. The flat surface portion and the fin portion may be one piece or may be separately molded or processed and combined by press fitting or the like. The material is preferably one that easily conducts heat, and examples thereof include aluminum, copper, iron, stainless steel, molybdenum, silicon nitride, and aluminum nitride. The shape of the fin portion does not necessarily have to be plate-shaped (fin-shaped) depending on the viscosity and velocity of the fluid and the direction of flow, and examples thereof include a cylinder, a prism, a square plate, and a pin.

(Outer shell member)
FIG. 4 shows the appearance of the outer shell member 40. In order to show the shape in an easy-to-understand manner, the central cross section is hatched. The outer shell member 40 has a tubular shape and is necessary for projecting the heat receiving member into the pipe through which the heat source fluid (high temperature fluid) flows. The heat source fluid may be any heat source that has a higher temperature than the low temperature side of the thermoelectric conversion module and can have a temperature difference, and may be described below using a high temperature fluid. The outer shell member 40 includes a hooking portion 42 along one end in the axial direction (z direction) of the cylinder 41 so that a surface for attaching the heat receiving member can be formed on the high temperature fluid side of the cylinder 41. FIG. 4 shows a configuration in which an annular member is attached to a tubular member as a hooking portion 42, and the hooking portion is sandwiched from a direction perpendicular to the other surface of the flat surface portion of the heat receiving member. It refers to a convex portion provided inward in the radial direction of the cylinder due to protrusion, bending, etc. so that it can be supported, and has a structure that is inclined in the direction in which the inner diameter of the cylinder of the outer shell member becomes smaller. But it's okay. The hooking portion 42 has an outer surface 42b which is an end surface of the outer shell member 40 and an inner surface 42a opposite to the outer surface 42b, and the inner surface 42a has a groove 43 for sandwiching a sealing member described later. That is, the outer shell member has a groove at a position where the sealing member is arranged. On the other hand, as a structure on the side where the outer shell member is attached to the pipe, for example, when the mounting pipe is branched with respect to the main pipe through which the high temperature fluid flows and the tip of the mounting pipe has a flange structure, the cylinder 41 It may be provided with a flange 44 of the same size that fits on the other side of the. Since the outer shell member comes into direct contact with a high-temperature fluid, heat resistance and strength are required, and iron, stainless steel, or the like is desirable.

(Configuration at the time of assembly)
FIG. 5 shows a cross-sectional view when the thermoelectric conversion device is assembled. The outer shell member 40 is arranged so as to surround the heat receiving member 30, the thermoelectric conversion module 10, and the cooling member 20. Here, the arrangement so as to surround means that the heat receiving member, the thermoelectric conversion module, and the cooling member are arranged inside the outer shell member when viewed from above in the axial direction of the cylinder.
At this time, the space 45 inside the end surface 42b of the hooked portion is difficult for the high-temperature fluid to flow in, and even if it does flow, it becomes a turbulent flow, and the fin portion 32 is difficult to receive heat. Therefore, it is preferable that the fin portion 32 surely protrudes toward the high temperature fluid side from the end surface 42b of the hook portion.
Since the heat receiving member may be damaged or deteriorated by long-term use, it is preferable that the heat receiving member can be easily disassembled and replaced from the outer shell member. Examples of the fastening method for this purpose include bolt fastening and the like.

(Relationship with mounting piping)
As an example of attaching the outer shell member to the main pipe through which the high temperature fluid flows, the case of attaching to the flange of the mounting pipe shown above will be described in detail. The flange may be applied to any configuration as long as it is within the range specified in JIS (Japanese Industrial Standards), for example. When the apparatus of the present invention is attached to the flange, it is preferable to use a gasket because it can withstand a specified pressure and easily maintain airtightness. Examples of the gasket include a soft gasket made of expanded graphite, PTFE material, etc., a semi-metal gasket such as a metal jacket gasket, a metallic metal gasket, a woven gasket, and the like.
As an example of the pipe to be attached, the shape as shown in FIG. 6 can be mentioned. That is, another mounting pipe 101 is attached to the side surface of the main pipe 100 through which the high temperature fluid flows in a direction orthogonal to the pipe, and the flange 102 is attached to the end of the mounting pipe 101. At this time, since it is assumed that the inside of the mounting pipe 101 becomes a stagnation of the flow of the high-temperature fluid, it is preferable that the heat receiving member avoids the stagnation region and protrudes into the main pipe 100 beyond the region.
This will be described with reference to FIG. The entire hooked portion 42 of the outer shell member protrudes into the main pipe through which the high temperature fluid flows from the inner wall 100a of the main pipe, and the fin portion 32 protrudes from the end surface 42b of the hooked portion, so that the fin portion 32 is exposed to the high temperature fluid. Make sure to place it in the flow of. This configuration may be rephrased as a fin portion and a part of the outer shell member protruding from the heat source fluid.

(1st jig)
FIG. 7 shows an external view of the first jig, but the configuration of the first jig is not limited to this. The first jig 50 has an annular holding portion 51, a plurality of pillar portions 52 whose axial direction is the axial direction of the annular holding portion 51, and an annular fastening portion 53. The plurality of pillars 52 are rotationally symmetric with respect to the annular (annular in FIG. 7) holding portion 51 and fastening portion 53 on one end side and the other end side in the axial direction (z direction), respectively. It is preferably placed or connected. More preferably, they are arranged or connected at equal intervals in the circumferential direction. The number of pillars 52 is preferably 3 or more. By sandwiching the end of the flat surface portion of the heat receiving member between the holding portion 51 of the first jig and the hooking portion of the outer shell member from a direction perpendicular to the other surface of the flat surface portion of the heat receiving member. , Supports the heat receiving member. The fastening portion 53 is fastened to the flange of the outer shell member. At this time, the dimensions of the fastening portion and the position of the outer surface 53a may be designed in consideration of the positional relationship with other members.

(Second jig)
An external view of the second jig that supports the thermoelectric conversion module across the cooling member is shown in FIG. 8 by hatching the central cross section in order to show the shape in an easy-to-understand manner. The configuration of the second jig is not limited to this. The second jig 60 includes an annular pressing portion 61, a plurality of pillar portions 62 whose longitudinal direction is the axial direction of the annular pressing portion 61, and an annular fastening portion 63. The plurality of pillar portions 62 are rotationally symmetric with respect to the annular (annular in FIG. 8) pressing portion 61 and fastening portion 63 on one end side and the other end side in the axial direction (z direction), respectively. It is preferably placed or connected. More preferably, they are arranged or connected at equal intervals in the circumferential direction. The number of pillars 52 is preferably 3 or more. The pressing portion of the second jig sandwiches the cooling member and presses and supports the thermoelectric conversion module toward the heat receiving member. At this time, in order to determine the installation position of the cooling member, the pressing portion 61 may be provided with a stepped portion 64 having the same dimensions as the outer shape of the cooling member 20, and the cooling member may be fitted therein. The fastening portion 63 is fastened to the flange 44 of the outer shell member.
For example, when the cooling member has a cylindrical shape as shown in FIG. 2, the pressing is performed while avoiding the refrigerant pipes and terminals. At this time, if the cooling member and the thermoelectric conversion module have sufficient rigidity, only the center of the cooling member may be pressed, and the outer peripheral portion of the cooling member is pressed in consideration of the variation in the pressing load due to elastic deformation. May be. In order to prevent the inner surface 63a of the fastening portion and the pressing portion 65 from interfering with the bolt for fastening the first jig and the first jig to the outer shell member, a relief hole 63b, a notch 65, etc. are provided. It may be provided.

(Avoiding heat loss from the first jig to the second jig)
In order to transfer the heat received by the heat receiving member to the thermoelectric conversion module, it is desirable to suppress the heat loss at the following two points. The first is the heat that escapes from the heat receiving member to the first jig, and the second is the heat that escapes from the first jig to other members.
First, regarding the first jig, it is considered that a metal material such as iron or stainless steel is preferable as a material having heat resistance and strength sufficient to support a heat receiving member in a high temperature environment. At this time, the sandwiching portion releases the heat received from the heat receiving member to the pillar portion or by releasing it to the outside air. In order to minimize this, it is preferable to reduce the volume of the holding portion as much as possible to reduce the heat capacity that can be stored, and further to make the cross-sectional area of the pillar portion as narrow as possible to make it difficult for heat to transfer from the holding portion.
Regarding the second, the first jig and the second jig are close to each other, and since this second jig is in contact with the cooling member, the temperature is low, and the temperature is lower than that of the first jig. The difference is large. If the first jig comes into contact with the second jig in any region, a large heat transfer occurs in the contact region. That is, when viewed from the first jig, heat is taken away, so that the heat transferred to the high temperature side of the thermoelectric conversion module is lost. On the other hand, when viewed from the second jig, the water cooling member is heated by receiving heat, which reduces the ability to cool the low temperature surface of the thermoelectric conversion module. Therefore, it is preferable that the contact area between the first jig and the second jig is as small as possible, and it is desirable that the first jig and the second jig are not in contact with each other, that is, they are not in contact with each other.

This will be described in more detail. The part where the first jig and the second jig may come into contact is between the pillar part of the first jig and the pillar part of the second jig, or the fastening part of the first jig. And between the fastening part of the second jig. As a method of avoiding contact between the pillars, the number and thickness of the pillars, the diameter connecting the center lines of each pillar, the mounting angle, and the like may be changed. As a method of avoiding contact between the fastening portions, the length of the pillar portion of the second jig may be adjusted.
A method of avoiding contact between the fastening portions will be described with reference to FIG. The pillar of the second jig is lengthened so as to provide a gap 110 between the outer surface 53a of the fastening portion of the first jig and the inner surface 63a of the fastening portion of the second jig. At this time, in order to prevent the bolt 501 for fastening the first jig 50 to the outer shell member 40 from interfering with the second jig 60, a relief hole 63b is provided at the fastening portion of the second jig. May be. Further, in order to prevent the bolt 601 for fastening the second jig 60 to the outer shell member 40 from interfering with the fastening portion 53 of the first jig, the diameter of the fastening portion is set at a position where the bolt 601 does not contact. You can make it as small as possible.
Here, the gap 110 from the outer surface 53a of the fastening portion of the first jig to the inner surface 63a of the fastening portion of the second jig is calculated as follows from the viewpoint of the thermal expansion rate. The calculation formula uses ΔL = α (T2-T1) L. L represents the length of the member before thermal expansion (mm), T2-T1 represents the temperature change (° C), and ΔL (delta L) represents the amount of thermal expansion (mm). For example, if the length of the pillar of the first jig and the pillar of the second jig are 100 mm each, the temperature of the second jig does not change, but the temperature of the first jig rises by 300 ° C. think. When the material is iron or stainless steel, the coefficient of thermal expansion α is estimated to be about 17.8 × 10 ^-6 / ° C, so the calculation result is ΔL = 0.54 mm. In order to prevent interference between the fastening portion of the first jig and the fastening portion of the second jig due to thermal expansion, it is preferable to leave a larger gap. That is, in the above example, the gap 110 may be thermally expanded by about 0.54% with respect to the length of the column, and from this, it is preferable to make it 1% or more. On the other hand, the upper limit of the gap 110 prevents the fastening bolt 601 of the second jig from being long and the tip of the bolt 601 being fastened to the flange of the outer shell member from being shortened, so that the thermoelectric power generation module can be sufficiently adjacent to the member. The gap 110 is preferably 5% or less because it can be brought into close contact with the water. Similarly, the distance 111 from the outer diameter of the fastening portion of the first jig to the fastening bolt of the second jig is preferably 1% or more and 5% or less of the length before thermal expansion.
With the above configuration, the first jig may be non-contact with the second jig.

(Sealing member)
The sealing member will be described with reference to FIG. The sealing member 70 is arranged so as to be sandwiched between the flat surface portion 31 of the heat receiving member and the inner surface 42a of the catching portion of the outer shell member in order to prevent leakage of the high temperature fluid. It is desirable to use a gasket or an O-ring for the sealing member because it is required to withstand a certain pressure and maintain airtightness as in the case of attaching the outer shell member to the flange. In particular, the O-ring has a circular cross section and is in contact with an adjacent member at a point, so that heat transfer is small. Therefore, it is more preferable to use an O-ring in order to prevent the heat received by the heat receiving member from escaping to the outer shell member.
The O-ring is preferably a metal O-ring made of metal and has a hollow cross section in consideration of heat resistance. Materials include stainless steel, Inconel, and Incoloy. When using a metal O-ring in a high-pressure environment exceeding about 7.0 MPa, it is better to use a metal O-ring with a hole for balance on the inner diameter side (for internal pressure) or the outer diameter side (for external pressure). Further, in order to improve airtightness and corrosion resistance, plating may be performed with silver, nickel, copper, gold or the like.
When using a metal O-ring, it is preferable to provide a groove 43 on the inner surface of the hooked portion of the outer shell member. Unless otherwise specified, the groove dimensions generally comply with JIS (Japanese Industrial Standards). Since the metal O-ring is less likely to be deformed than the rubber one, in order to ensure airtightness, the surface that the O-ring contacts, that is, the bottom surface of the U-shaped groove 43 and the flat surface portion 31 of the heat receiving member are flattened. For example, the arithmetic average roughness Ra is preferably 1.6 μm or less. As a result, the pressing force applied to the O-ring and its repulsive force can be brought into close contact with each other.

Examples will be described below.
(Configuration of thermoelectric converter)
The material of the thermoelectric conversion element is a scutterdite system, and a thermoelectric conversion module in which 32 pairs of elements are connected as shown in Fig. 1 was used. As shown in FIG. 2, the cooling member used was a copper cylindrical cooling plate having a water channel formed therein. It was covered with a stainless steel cap so as to be integrated with the thermoelectric conversion module, and the outer circumference of the cap was welded to a cooling member and vacuum-sealed. The heat receiving member is copper, and as shown in Fig. 3, the shape is such that nine plate-shaped fins are vertically erected on a disk-shaped flat surface. The fin portion was press-fitted into a groove dug to a depth that did not penetrate the flat surface portion. The thickness of one fin part is 5 mm, the length of the plate is 90 mm, the width is the largest in the plate passing through the center of the circle, and becomes smaller as it goes away from the center of the circle, and is 26 to 69 mm. The outer shell member is made of stainless steel having the shape shown in Fig. 4, and a hooked part with a plate thickness of 6 mm is welded to a cylinder with a wall thickness of 5 mm. The bottom surface of the groove of the hooked part was set to 0.8 μm in arithmetic average roughness Ra. A gasket was used between the mounting pipe and the outer shell member. The first jig had the shape shown in Fig. 7, had four pillars, and was made of stainless steel. In the second jig, the material of the pressing portion was iron, the number of pillars was 12, and the other parts had the same configuration as in FIG. The pillars of the first jig and the second jig were arranged so as not to interfere with each other, that is, they were not in contact with each other. At this time, in order to prevent the pillar portion 52 of the first jig from interfering with the pressing portion 61 of the second jig, a notch 65 is provided in the pressing portion. Further, the gap 110 from the fastening portion of the first jig to the fastening portion of the second jig is set to a distance of 2 mm, and the distance 111 from the fastening portion of the first jig to the fastening bolt 601 is set to 5 mm. The sealing member used was a metal O-ring that was hollow, had a circular cross section with an outer diameter of φ2.4 mm, and was made of 321 steel. A groove matching the size of the metal O-ring is provided in the hooked portion of the outer shell member in accordance with JIS standards.

(Assembly procedure)
FIG. 9 is a diagram in which the members constituting the thermoelectric conversion device are disassembled and arranged in a row in order to make it easy to understand the assembly order. Assembly was done in 3 steps. The first stage is the assembly from the outer shell member to the first jig. The sealing member 70, the heat receiving member 30, and the first jig 50 are arranged in this order in the outer shell member 40, and these are fastened to the outer shell member 40 by bolting the first jig 50. I restrained it all together. In the second stage, after inserting the thermoelectric module 10 and the cooling member 20 into the cylinder of the outer shell member 40, the second jig 60 is placed and the second jig 60 is placed. A thermoelectric conversion device was assembled by bolting to the outer shell member 40. In the third stage, the outer shell member was attached to the flange of the piping flange via a gasket. At this time, the fin portion and a part of the outer shell member protruded into the high temperature fluid. After that, a water pipe was connected to the cooling member 20, and an electric wiring was connected to the thermoelectric conversion module 10 via a terminal.

(Test conditions and results)
A thermoelectric conversion device was installed in the mounting piping branched from the main piping that uses the exhaust gas of the internal combustion engine as a high-temperature fluid, and a test was conducted to generate electricity from the thermoelectric conversion module. The temperature of the hot fluid was 293.0 ° C, 340.5 ° C, 387.1 ° C and 443.0 ° C, and the wind speed and internal pressure increased in proportion to the increase in temperature. K thermocouples were installed at four locations, and the temperature of the high-temperature fluid, the temperature at the intermediate position of the fins of the heat-receiving member, the temperature of the flat surface of the heat-receiving member, and the temperature of the cooling member were measured, respectively. As for water, circulating water with a set temperature of 30 ° C was flowed from a separately installed cooling facility. Since it is not possible to directly measure the temperature of the hot and cold surfaces of the thermoelectric conversion module during the test, the temperature of the flat surface of the heat receiving member is assumed to be the temperature of the high temperature surface of the thermoelectric conversion module, and the temperature of the cooling member is thermoelectrically converted. Assuming the low temperature of the module, the difference between these temperatures was calculated as a simple ΔT (delta T).
The results are shown in FIG. The temperature of the fin part showed a value very close to the gas temperature (temperature of high temperature fluid) on the horizontal axis. Based on the gas temperature, the heat loss to the flat surface was about 8.5%, and the temperature rise rate of the cooling plate was about 4.8%. As a result, the temperature difference ΔT (delta T) was suppressed to a loss of about 9.6% compared to the ideal value (= gas temperature-cooling set temperature). It is presumed that the reason why the temperature drop on the flat surface is larger than the temperature rise on the cooling plate is that the heat of this difference is released to the outside air. Regarding gas leakage, no leakage occurred from the sealing member.
As a result, it was possible to prevent the outflow of fluid due to the pressure difference between the inside and outside of the furnace due to the installation of the thermoelectric conversion module, to easily collect heat from the fluid of the heat source, and to reduce the heat loss.

10: Thermoelectric conversion module
11: P-type element
12: N-type element
13: High temperature side electrode
14: Low temperature side electrode
15: Insulated substrate
16: End of electrode
20: Cooling member
22: Cap
23: Refrigerant piping
24: Terminal
30: Heat receiving member
31: Flat surface
32: Fin part
40: Outer shell member
41: Cylinder
41a: Inner wall of the cylinder
42: Hooking part
42a: Inner surface of the hook
42b: End face of the hook
43: Groove
44: Flange
45: Fluid stagnation space
50: First jig
51: Holding part
52: Pillar part
53: Fastening part
53a: Outer surface of fastening part
60: Second jig
61: Pressing part
62: Pillar part
63: Fastening part
63a: Inner surface of fastening part
63b: escape hole
64: Stepped part
65: Notch
70: Sealing member
100: Main piping
100a: Inner wall of main pipe
101: Mounting piping
102: Flange
110: Gap between the fastening part of the first jig and the fastening part of the second jig
111: Distance from the fastening part of the first jig to the bolt for fastening the second jig to the outer shell member.
501: Fastening bolt
601: Fastening bolt

Claims (5)

Thermoelectric conversion module and
A heat receiving member having a flat surface portion and fin portions erected on one surface of the flat surface portion, and having the other surface of the flat surface portion closely arranged on one side of the thermoelectric conversion module.
A cooling member arranged in close contact with the other side of the thermoelectric conversion module, and
A tubular outer shell member arranged so as to surround the heat receiving member, the thermoelectric conversion module, and the cooling member.
A first jig that sandwiches and supports the end of the flat surface portion of the heat receiving member between the outer shell member and the outer shell member from a direction perpendicular to the other surface of the flat surface portion of the heat receiving member.
A second jig that supports the thermoelectric conversion module by sandwiching the cooling member, and
A sealing member arranged between the flat surface portion of the heat receiving member and the outer shell member, and
A thermoelectric conversion device characterized by having. The thermoelectric conversion device according to claim 1, wherein the outer shell member has a groove at a position where the sealing member is arranged. The thermoelectric conversion device according to claim 1 or 2, wherein the first jig is not in contact with the second jig. The first jig supports the heat receiving member by sandwiching and supporting the end portion of the flat surface portion of the heat receiving member with the outer shell member via the sealing member from a direction perpendicular to the other surface of the flat surface portion of the heat receiving member. The thermoelectric conversion device according to any one of claims 1 to 3, wherein the holding portion and the pillar portion supporting the holding portion are provided. The thermoelectric conversion device according to any one of claims 1 to 4, wherein the fin portion and a part of the outer shell member project to the heat source fluid.

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