JP7589468B2 - Thermoelectric conversion device - Google Patents

Description

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

In recent years, in order to reduce energy consumption, efforts have been made to recover exhaust heat from heat sources such as boilers, incinerators, and automobiles as electricity. In particular, thermoelectric conversion modules that can efficiently recover electrical energy using thermoelectric elements that can directly convert thermal energy into electrical energy through the Seebeck effect have attracted attention. A thermoelectric module is a combination of P-type and N-type thermoelectric conversion elements connected alternately via electrodes, with one side being the high-temperature side and the other being the low-temperature side, generating electricity by creating a temperature difference between the two sides. It is expected that this will be put to practical use as a clean method for effectively utilizing exhaust heat that has previously been discarded. In particular, development is underway because it has the potential to recover large electrical energy from large temperature differences by using thermoelectric conversion elements made of materials that can be used in high-temperature environments of approximately 300°C or higher.

To create a large temperature difference in a thermoelectric conversion module using a fluid such as high-temperature gas, it is important to transfer heat from the fluid to the high-temperature side without loss, reduce heat transfer to the low-temperature side from sources other than the thermoelectric conversion element, and increase the temperature difference between the high-temperature and low-temperature sides.

For example, Patent Document 1 discloses a thermoelectric conversion power generation unit in which a thermoelectric conversion module is held by a heat receiving member and a cooling member. It also discloses a configuration in which the thermoelectric conversion power generation unit has a heating section and a cooling section and is installed in a tunnel furnace in which heated objects are transported sequentially inside the heating section and the cooling section.

Patent Document 2 also discloses a thermoelectric conversion device in which one side of a thermoelectric conversion module is placed on a heat receiving plate attached to the opening of a furnace, the other side of the thermoelectric conversion module is attached by being in close contact with and fixed to a water-cooled plate, and a heat receiving fin is formed on the heat receiving side of the heat receiving plate inside the furnace.

JP 2004-350479 A JP 2013-211471 A

In Patent Document 1, because the heat-receiving member and the cooling member are held together, there is an issue that heat is easily lost due to conduction from the heat-receiving member to the cooling member. In addition, heat loss is also likely to occur in the heating section and cooling section of the tunnel furnace, making it difficult to obtain a large temperature difference in the thermoelectric conversion module.

In Patent Document 2, the heat receiving plate is in contact with the case, and it is possible that the heat collected by the heat receiving plate travels through the internal components of the case, reducing the temperature difference with the water-cooled plate. Furthermore, if the pressure of the high-temperature gas on the heat receiving side is higher than that outside the furnace, a gap may develop between the case and the heat receiving plate.

The object of the present invention is to provide a thermoelectric conversion device that prevents the outflow of fluid due to the pressure difference between the inside and outside of the facility caused by the installation of a thermoelectric conversion module, makes it easy to collect heat from the heat source fluid, and further reduces heat loss.

The thermoelectric conversion device of the present invention includes a thermoelectric conversion module, a heat-receiving member, a cooling member, an outer shell member, a first jig, a second jig, and a sealing member.
The heat receiving member is
A flat surface portion and a fin portion erected on one surface of the flat surface portion,
the other surface of the flat surface portion is disposed in close contact with one side of the thermoelectric conversion module ,
The cooling member is
The thermoelectric conversion module is disposed in close contact with the other side of the thermoelectric conversion module .
The outer shell member is
The flange includes a cylinder and a hook portion provided at one end of the cylinder in an axial direction.
the heat receiving member is disposed so as to surround the thermoelectric conversion module, the heat receiving member, and the cooling member;
The first jig includes:
The clamping member has an annular clamping portion, a plurality of pillar portions whose longitudinal direction is the axial direction of the clamping portion, and an annular fastening portion,
the end of the flat surface portion of the heat-receiving member is sandwiched between the clamping portion of the first jig and the hook portion of the outer shell member in a direction perpendicular to the other surface of the flat surface portion of the heat-receiving member, thereby supporting the heat-receiving member;
The second jig includes:
The annular pressing portion includes a plurality of pillar portions having a longitudinal direction in the axial direction of the annular pressing portion, and an annular fastening portion.
the pressing portion supports the thermoelectric conversion module by pressing the thermoelectric conversion module against the heat receiving member with the cooling member sandwiched therebetween;
The column portion of the first jig and the column portion of the second jig are disposed at positions where they do not interfere with each other;
A gap is provided between an outer surface of the fastening portion of the first jig and an inner surface of the fastening portion of the second jig,
The sealing member is
a flat surface of the heat-receiving member and an inner surface of the hook of the outer shell member;
By fastening the first jig to the outer shell member, the first jig, the sealing member, and the outer shell member are integrally constrained.
It is characterized by:

Furthermore, it is preferable that an O-ring serving as the sealing member is disposed in a groove on the inner side of the hook portion of the outer shell member.

Furthermore, it is preferable that the fin portion and a part of the outer shell member protrude into the heat source fluid.

According to the present invention, in a thermoelectric conversion device, the installation of a thermoelectric conversion module prevents the outflow of fluid due to the pressure difference between the inside and outside of the facility, makes it easier to collect heat from the heat source fluid (high-temperature fluid), and further reduces heat loss.

Schematic diagram of the thermoelectric conversion module FIG. 1 is a perspective view showing a cooling member integrated with a thermoelectric conversion module; External view of heat receiving member 3 is a cross-sectional perspective view of the outer shell member; Cross-sectional view of the thermoelectric conversion device Example of piping to which the device is attached External view of the first jig External view of the second jig Cross-sectional view of a thermoelectric conversion device Graph showing the relationship between gas temperature and temperature at each point

An embodiment of the thermoelectric conversion device of the present invention will be described below.
A thermoelectric conversion module;
a heat-receiving member having a flat surface portion and a fin portion erected on one surface of the flat surface portion, the heat-receiving member being disposed on one side of the thermoelectric conversion module with the other surface of the flat surface portion being in close contact with the one side of the thermoelectric conversion module;
a cooling member disposed in close contact with the other side of the thermoelectric conversion module;
a cylindrical shell member arranged to surround the heat receiving member, the thermoelectric conversion module, and the cooling member;
a first jig for supporting an end of the flat surface portion of the heat-receiving member by sandwiching it between the first jig and the outer shell member;
a second jig that supports the thermoelectric conversion module by sandwiching the cooling member; and
a sealing member disposed between the flat surface portion of the heat-receiving member and the outer shell member;
The configuration of each is explained below.

(Thermoelectric conversion module)
The appearance of a thermoelectric conversion module is shown in Figure 1. P-type and N-type thermoelectric conversion elements are connected via electrodes, with one side being the high temperature side and the other being the low temperature side, and power conversion is performed by creating a temperature difference between the two sides. At this time, in the N-type element, electrons with a high density on the high temperature side flow to the low temperature side, and in the P-type element , positively charged holes flow to the low temperature side, creating a reverse potential difference and causing a current to flow. The phenomenon in which a temperature difference generates a thermoelectromotive force is called the Seebeck effect.

In FIG. 1, an example is shown as 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 end 16. In order to show the arrangement of the elements and electrodes, the insulating substrate 15 is shown with the break lines removed from the boundary. A pair is made up of a P-type and an N-type connected by an electrode. The amount of power generated by one pair is extremely small, about 1 to 100 mW depending on the temperature difference, but connecting multiple such pairs is preferable because it is possible to obtain a large amount of power generation. In addition, the voltage of one pair is low, but it is possible to increase the voltage by arranging them electrically in series, and further to increase the voltage using a DC-DC converter for boosting the voltage to obtain a voltage value that can be used in commercial products.

For high temperatures of 300°C or higher, it is preferable to use materials such as _Mg2Si , silicide, half-Heusler, and skutterudite for the thermoelectric conversion element. These materials may oxidize when exposed to air in high temperature regions, so it is preferable to suppress oxidation by, for example, sealing in a vacuum atmosphere, i.e., vacuum sealing. The vacuum sealing may be performed by enclosing only the region near the outer periphery of the thermoelectric conversion module, or may be performed by sealing the thermoelectric conversion module integrally with a 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 flat surfaces and is cooled by a cooling medium (refrigerant). The flat surface of the cooling member is brought into close contact with the low-temperature side surface of the thermoelectric conversion module, thereby cooling the low-temperature side surface of the thermoelectric conversion module. An example in which the cooling member and the thermoelectric conversion module are integrated will be described below. FIG. 2 shows a schematic exploded view of a part of a thermoelectric conversion device integrated with a thermoelectric conversion module. The components are a thermoelectric conversion module 10, a cooling member 20, a cap 22, a refrigerant pipe 23, and a terminal 24. The cooling member 20 may be a water-cooled plate, and as described above, as long as it has a surface for cooling the low-temperature side of the thermoelectric conversion module, it may be in the form of a plate or a shape having a water channel structure on the opposite side of the main surface.

Below, an example of a cooling member using water as the refrigerant will be described. In this case, the refrigerant piping may be interpreted as a water pipe, a water hose, or a water tube. The cooling member is sized to fit comfortably within the outer shell member described below. This makes it possible to arrange the cooling member while maintaining a gap inside the outer shell member. The shape of the cooling member may be any shape as long as it has a flat surface wider than the thermoelectric conversion module so that the entire low-temperature surface of the thermoelectric conversion module can be in close contact with it, and the contact surface is thick enough to be cooled sufficiently by the cooling medium.
Generally, aluminum, copper, or stainless steel is used as the material for the cooling member, and any of them will do, but copper is preferable from the viewpoint of high thermal conductivity, and nickel plating is even better to prevent oxidation.
The cooling member 20 in FIG. 2 is a diagram showing a case where the cooling member is cylindrical and is provided with a refrigerant pipe 23 that serves as an inlet and outlet for water. The low-temperature surface of the thermoelectric conversion module 10 is attached to one side of the cylindrical shape, covered with a cap 22, and the outer periphery of the cap 22 is welded to the cooling member 20 in a vacuum atmosphere, thereby vacuum-sealing the thermoelectric conversion module. The cap 22 is large enough to completely cover the thermoelectric conversion module, and has a shape of a container with a brim. Stainless steel and the like are preferable as materials that have heat resistance and oxidation resistance that are not a problem even if they are in contact with the heat-receiving member for a long time, and have the strength to maintain the vacuum seal. Furthermore, it is desirable to make the wall thickness as thin as possible 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.
When the electric current generated in the thermoelectric conversion module is taken out of the vacuum-sealed space, a terminal 24 is used. The terminal 24 may be, for example, a single conductor wire with a welding material on the outer periphery via an insulating material such as ceramics or glass. Copper, stainless steel, nickel, Fe-Ni-Co alloy, etc. are often used as the material for the conductor wire and the joint. When taking out the electric current, for example, if the electric current is taken out in the XY direction, a small terminal may be used. It is preferable to take out the electric current away from the heat source in order to avoid contact with the adjacent heat-receiving member and leakage of the electric current, and to prevent the insulating member from touching the heat-receiving member and escaping heat. For example, the terminal may be arranged in the direction of the cooling member. In this case, specifically, a terminal may be welded to the cooling member so as not to interfere with the flow path of the cooling medium, and the tip of the terminal may be joined to the end 16 of the electrode of the thermoelectric conversion module, so that the generated electric power can be taken out into the atmosphere.
When sandwiching the thermoelectric conversion module between the cooling member and the cap in the z direction, it is preferable to sandwich a ceramic substrate between the cap and the thermoelectric conversion module to maintain insulation, and to further sandwich a graphite sheet to enhance adhesion.

(Heat receiving member)
FIG. 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 vertically (in the z direction) erected on one surface of the flat surface portion 31 of a plate shape. 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 be flat as shown in FIG. 3, and may have a slight change in thickness or a structure such as a groove for forming the fin portion. The flat surface portion and the fin portion may be either one body or separately molded or processed and combined by press fitting or the like. The material is preferably one that easily transfers heat, such as aluminum, copper, iron, stainless steel, molybdenum, silicon nitride, aluminum nitride, etc. The shape of the fin portion does not necessarily have to be plate-like (fin-like), and may be a cylinder, a square column, a square plate, a pin, etc. depending on the viscosity, speed, and flow direction of the fluid.

(Outer shell member)
FIG. 4 shows the appearance of the outer shell member 40. To make the shape easier to understand, the central cross section is hatched. The outer shell member 40 is cylindrical in shape and is necessary to protrude the heat receiving member into the pipe through which the heat source fluid (high temperature fluid) flows. The heat source fluid may be a heat source that is higher in temperature than the low temperature side of the thermoelectric conversion module and can create a temperature difference, and hereinafter, the description may be given using the high temperature fluid. The outer shell member 40 has a hook portion 42 along one end of the axial direction (z direction) of the tube 41 so that a surface for attaching the heat receiving member to the high temperature fluid side of the tube 41 can be formed. FIG. 4 shows a configuration in which an annular member is attached to a cylindrical member as the hook portion 42, but this hook portion refers to a convex portion provided radially inward of the tube by protruding, bending, etc. so that the heat receiving member can be supported by being sandwiched from a direction perpendicular to the other surface of the flat surface portion of the heat receiving member, and may have a structure inclined in a direction in which the inner diameter of the tube of the outer shell member becomes smaller. The hook portion 42 has an outer surface 42b, which is the end face of the outer shell member 40, and an inner surface 42a opposed thereto, and the inner surface 42a has a groove 43 for sandwiching a sealing member, which will be described later. That is, the outer shell member has a groove at a position where the sealing member is to be disposed. On the other hand, as a structure on the side where this outer shell member is attached to the piping, for example, when an attachment pipe branches off from a main pipe through which a high-temperature fluid flows and the tip of the attachment pipe has a flange structure, a flange 44 of the same size that fits the other side of the tube 41 may be provided. The outer shell member is in direct contact with the high-temperature fluid, so it needs to be heat-resistant and strong, and is preferably made of iron, stainless steel, or the like.

(Assembled configuration)
5 shows a cross-sectional view of the thermoelectric conversion device when 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, "arranged 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 tube.
At this time, the high-temperature fluid does not easily flow into space 45 inside end face 42b of the hook portion, and even if it does flow, the flow is turbulent, making it difficult for fin portion 32 to receive heat. Therefore, it is preferable that fin portion 32 protrudes reliably toward the high-temperature fluid side beyond end face 42b of the hook portion.
Since the heat-receiving member may be damaged or deteriorated after long-term use, it is preferable that it can be easily disassembled and replaced from the outer shell member. As a fastening method for this purpose, bolt fastening or the like can be used.

(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 it to the flange of the attachment 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 by, for example, JIS (Japanese Industrial Standards). When attaching the device of the present invention to the flange, it is preferable to use a gasket, since it can withstand the specified pressure and easily maintain airtightness. Examples of gaskets include soft gaskets made of expanded graphite or PTFE material, semi-metal gaskets such as metal jacket gaskets, metallic metal gaskets, and woven fabric gaskets.
An example of the pipe to which the heat receiving member is attached is shown in Fig. 6. That is, a separate attachment pipe 101 is attached to the side of a main pipe 100 through which a high-temperature fluid flows, in a direction perpendicular to the main pipe, and a flange 102 is attached to the end of the attachment pipe 101. Since it is assumed that the flow of the high-temperature fluid will stagnate inside the attachment pipe 101, it is preferable that the heat receiving member avoids the stagnation area and protrudes into the main pipe 100 beyond it.
This will be explained with reference to Fig. 5. The entire hook portion 42 of the outer shell member protrudes beyond the inner wall 100a of the main pipe into the main pipe where the high temperature fluid flows, and the fin portion 32 protrudes from the end face 42b of the hook portion, so that the fin portion 32 is reliably positioned in the flow of the high temperature fluid. This configuration can also be said to be such that the fin portion and a part of the outer shell member protrude into the heat source fluid.

(First jig)
FIG. 7 shows an external view of the first jig, but the configuration of the first jig is not limited thereto. The first jig 50 has an annular clamping portion 51, a plurality of columnar portions 52 whose longitudinal direction is the axial direction of the annular clamping portion 51, and an annular fastening portion 53. The plurality of columnar portions 52 are preferably arranged or connected at rotationally symmetric positions with respect to the annular (circular in FIG. 7) clamping portion 51 and fastening portion 53 at one end side and the other end side in the axial direction (z direction). More preferably, they are preferably arranged or connected at equal intervals in the circumferential direction. The number of columnar portions 52 is preferably three or more. The clamping portion 51 of the first jig supports the heat receiving member by clamping the end of the flat surface portion of the heat receiving member between the hook portion of the outer shell member and the hook portion of the outer shell member from a direction perpendicular to the other surface of the flat surface portion of 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, etc., can be designed taking into consideration the positional relationship with other members.

(Second jig)
FIG. 8 shows an external view of the second jig for supporting the thermoelectric conversion module by sandwiching the cooling member, and the central cross section is hatched to clearly show the shape. The configuration of the second jig is not limited to this. The second jig 60 is composed of an annular pressing part 61, a plurality of column parts 62 whose longitudinal direction is the axial direction of the annular pressing part 61, and an annular fastening part 63. The plurality of column parts 62 are preferably arranged or connected at rotationally symmetric positions with respect to the annular (circular in FIG. 8) pressing part 61 and fastening part 63 at one end side and the other end side in the axial direction (z direction). More preferably, they are preferably arranged or connected at equal intervals in the circumferential direction. The number of column parts 52 is preferably three or more. The pressing part of the second jig presses the thermoelectric conversion module toward the heat receiving member by sandwiching the cooling member, and supports it. At this time, in order to determine the installation position of the cooling member, a stepped portion 64 having the same dimensions as the outer shape of the cooling member 20 may be provided in the pressing portion 61, 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 is cylindrical 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, or the outer periphery of the cooling member may be pressed in consideration of variations in pressing load due to elastic deformation. In order to prevent the inner surface 63a of the fastening portion and the pressing portion 65 from interfering with the first jig and the bolts for fastening the first jig to the outer shell member, a relief hole 63b, a notch 65, or the like may be provided.

(Avoiding heat loss from the first fixture to the second fixture)
To transfer the heat received by the heat-receiving member to the thermoelectric conversion module, it is desirable to reduce the heat loss at the following two points: the first is the heat escaping from the heat-receiving member to the first jig, and the second is the heat escaping from the first jig to other members.
Regarding the first point, it is considered that the first jig is best made of a metal material such as iron or stainless steel, which has heat resistance and strength sufficient to support the heat-receiving member in a high-temperature environment. In this case, the clamping part transfers the heat received from the heat-receiving member to the column part or releases it into the outside air. To minimize this, it is preferable to reduce the volume of the clamping part as much as possible to reduce the heat capacity that can be stored, and further to narrow the cross-sectional area of the column part as much as possible to make it difficult for heat to move from the clamping part.
Regarding the second point, the first and second jigs are close to each other, and the second jig is in contact with the cooling member, so its temperature is low and the temperature difference is large compared to the first jig. If the first jig comes into contact with the second jig in any area, a large heat transfer occurs in that contact area. In other words, from the perspective of the first jig, heat is taken away, and the heat to be transferred to the high-temperature side of the thermoelectric conversion module is lost. On the other hand, from the perspective of the second jig, the water-cooling member is heated by the heat received, which reduces the ability to cool the low-temperature side of the thermoelectric conversion module. For this reason, it is preferable to make the contact area between the first and second jigs as small as possible, and it is even more preferable that they are not in contact with each other, i.e., they are non-contact.

This will be explained in more detail. The parts where the first jig and the second jig may come into contact are between the column part of the first jig and the column part of the second jig, or between the fastening part of the first jig and the fastening part of the second jig. In order to avoid contact between the column parts, the number and thickness of the column parts, the diameter connecting the center lines of the column parts, the mounting angle, etc. may be changed. In order to avoid contact between the fastening parts, the length of the column part of the second jig may be adjusted.
A method for avoiding contact between the fastening parts will be described with reference to Fig. 5. The pillar of the second jig is lengthened so as to provide a gap 110 between the outer surface 53a of the fastening part of the first jig and the inner surface 63a of the fastening part of the second jig. At this time, in order to prevent the bolt 501 for fastening the first jig to the outer shell member 40 from interfering with the second jig 60, an escape hole 63b may be provided in the fastening part of the second jig. Also, in order to prevent the bolt 601 for fastening the second jig to the outer shell member 40 from interfering with the fastening part 53 of the first jig, the diameter of the fastening part may be reduced to a position where the bolt 601 does not come into contact.
Here, the gap 110 between the outer surface 53a of the fastening part of the first jig and the inner surface 63a of the fastening part of the second jig is calculated from the viewpoint of the thermal expansion coefficient as follows. The calculation formula used is ΔL=α(T2-T1)L. L represents the length of the member before thermal expansion (mm), T2-T1 represents the temperature change (℃), and ΔL (delta L) represents the amount of thermal expansion (mm). For example, consider a case where the length of the column part of the first jig and the column part of the second jig are each 100 mm, the temperature of the second jig does not change, but the temperature of the first jig rises by 300℃. When the material is iron or stainless steel, the thermal expansion coefficient α is estimated to be about 17.8×10 ^-6 /℃ at most, so the calculation result is ΔL=0.54 mm. It is preferable to leave a gap larger than this in order to prevent interference between the fastening parts of the first jig and the fastening parts of the second jig due to thermal expansion. That is, in the above example, it is considered that the gap 110 may thermally expand by about 0.54% relative to the length of the column, and for this reason, it is preferable to set it to 1% or more. On the other hand, the upper limit of the gap 110 is preferably 5% or less, in order to prevent the fastening bolt 601 of the second jig from being long and the length at which its tip is fastened to the flange portion of the outer shell member from becoming short, and to allow the thermoelectric power generation module to be sufficiently closely attached to the adjacent member. Similarly, it is preferable that the distance 111 from the outer diameter of the fastening portion of the first jig to the fastening bolt of the second jig is 1% or more and 5% or less of the length before thermal expansion.
With the above configuration, the first jig may be out of contact with the second jig.

(Sealing member)
The sealing member will be described with reference to FIG. 5. The sealing member 70 is placed between the flat surface portion 31 of the heat-receiving member and the inner surface 42a of the hook portion of the outer shell member to prevent leakage of high-temperature fluid from between them. As with the above-mentioned case of attaching the outer shell member to a flange, the sealing member is required to withstand a certain amount of pressure and maintain airtightness, so it is desirable to use a gasket or an O-ring. In particular, an O-ring has a circular cross section and contacts adjacent members at points, so there is little heat transfer. Therefore, it is more preferable to use an O-ring to prevent the heat received by the heat-receiving member from escaping to the outer shell member.
Considering heat resistance, it is preferable that the O-ring is made of metal and has a hollow cross section. Materials include stainless steel, Inconel, Incoloy, etc. Among metal O-rings, when used in a high-pressure environment exceeding approximately 7.0 MPa, it is better to use one with a balancing hole on the inner diameter side (for internal pressure) or outer diameter side (for external pressure). In addition, it may be plated with silver, nickel, copper, gold, etc. to improve airtightness and corrosion resistance.
When using a metal O-ring, it is preferable to provide a groove 43 on the inner surface of the hook of the outer shell member. The dimensions of the groove generally conform to JIS (Japanese Industrial Standards) unless otherwise specified. Metal O-rings are less likely to deform than rubber O-rings, so to ensure airtightness, it is preferable to flatten the surface that the O-ring comes into contact with, i.e., the bottom surface of the U-shaped groove 43 and the flat surface portion 31 of the heat-receiving member, and for example, to have an arithmetic mean roughness Ra of 1.6 μm or less. This allows the O-ring to be tightly attached by the pressing force and the repulsive force applied to it.

An embodiment will be described below.
(Configuration of Thermoelectric Conversion Device)
The thermoelectric conversion element was made of a skutterudite material, and a thermoelectric conversion module with 32 pairs of elements connected as shown in Figure 1 was used. The cooling member was a cylindrical copper cooling plate with water channels formed on it, as shown in Figure 2. It was covered with a stainless steel cap to be integrated with the thermoelectric conversion module, and the outer periphery of the cap was welded to the cooling member to seal it in a vacuum. The heat-receiving member was made of copper, and as shown in Figure 3, it had nine plate-shaped fins standing vertically on a circular flat surface. The fins were pressed into grooves dug deep enough not to penetrate the flat surface. The thickness of each fin was 5 mm, the length of the plate was 90 mm, and the width was 26 to 69 mm, with the largest plate passing through the center of the circle and decreasing as it moved away from the center. The outer shell member was made of stainless steel, as shown in Figure 4, and a 6 mm thick hook was welded to a 5 mm thick tube. The arithmetic mean roughness Ra of the bottom surface of the groove of the hook was 0.8 μm. A gasket was used between the mounting pipe and the outer shell member. The first jig had a shape as shown in FIG. 7, had four columns, and was made of stainless steel. The second jig had a pressing part made of iron, 12 columns, and other configurations were the same as those in FIG. 8. The columns 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, a notch 65 was provided in the pressing part to prevent the column part 52 of the first jig from interfering with the pressing part 61 of the second jig. In addition, the gap 110 from the fastening part of the first jig to the fastening part of the second jig was set to a distance of 2 mm, and the distance 111 from the fastening part of the first jig to the fastening bolt 601 was set to 5 mm. A metal O-ring was used as the sealing member, which was hollow, had a circular cross section with an outer diameter of φ2.4 mm, and was made of 321 steel. A groove was provided in the hook portion of the outer shell member to match the size of the metal O-ring in accordance with JIS standards.

(Assembly procedure)
FIG. 9 is a diagram in which the components constituting the thermoelectric converter are disassembled and arranged in a row to make the assembly order of the components easier to understand. The assembly was performed in three stages. The first stage was 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 were arranged in this order inside the outer shell member 40, and the first jig 50 was bolted to the outer shell member 40 to bind them together. In the second stage, the thermoelectric module 10 and the cooling member 20 integrated together were inserted into the cylinder of the outer shell member 40, and then the second jig 60 was arranged and bolted to the outer shell member 40 to assemble the thermoelectric converter. 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 were protruding into the high-temperature fluid. After that, a water pipe was connected to the cooling member 20, and electrical wiring was connected to the thermoelectric conversion module 10 via a terminal.

(Test conditions and results)
A thermoelectric conversion device was installed in an attachment pipe branched from the main pipe, which carries the exhaust gas from an internal combustion engine as a high-temperature fluid, and a test was conducted to generate electricity from the thermoelectric conversion module. The temperatures of the high-temperature fluid were 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-type thermocouples were installed in four locations to measure the temperature of the high-temperature fluid, the temperature at the middle 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. Water was circulated from a separate cooling facility at a set temperature of 30°C. During the test, the temperatures of the high-temperature and low-temperature surfaces of the thermoelectric conversion module could not be measured directly, so the temperature of the flat surface of the heat-receiving member was assumed to be the high-temperature surface temperature of the thermoelectric conversion module, and the temperature of the cooling member was assumed to be the low-temperature surface temperature of the thermoelectric conversion module, and the difference between these temperatures was calculated as a simplified ΔT (delta T).
The results are shown in Figure 10. The temperature of the fins was very close to the gas temperature (temperature of the high-temperature fluid) on the horizontal axis. Using the gas temperature as the standard, the heat loss to the flat surface was approximately 8.5%, and the temperature rise rate of the cooling plate was approximately 4.8%. As a result, the temperature difference ΔT (Delta T) was kept to a loss of approximately 9.6% compared to the ideal value (gas temperature - cooling set temperature). It is presumed that the reason the temperature drop of the flat surface was greater than the temperature rise of the cooling plate is because this difference in heat was released into the outside air. With regard to gas leakage, no leakage occurred from the sealing members.
This prevents the outflow of fluid due to the pressure difference between the inside and outside of the furnace caused by the installation of the thermoelectric conversion module, makes it easier to collect heat from the heat source fluid, and reduces heat loss.

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

Claims (3)

The thermoelectric conversion module includes a heat receiving member, a cooling member, an outer shell member, a first jig, a second jig, and a sealing member.
The heat receiving member is
A flat surface portion and a fin portion erected on one surface of the flat surface portion,
the other surface of the flat surface portion is placed in close contact with one side of the thermoelectric conversion module covered with a cap ;
The cooling member is
The thermoelectric conversion module is disposed in close contact with the other side of the thermoelectric conversion module .
The outer shell member is
The flange includes a cylinder and a hook portion provided at one end of the cylinder in an axial direction.
the heat receiving member is disposed so as to surround the thermoelectric conversion module, the heat receiving member, and the cooling member;
The first jig includes:
The clamping member has an annular clamping portion, a plurality of pillar portions whose longitudinal direction is the axial direction of the clamping portion, and an annular fastening portion,
the end of the flat surface portion of the heat-receiving member is sandwiched between the clamping portion of the first jig and the hook portion of the outer shell member in a direction perpendicular to the other surface of the flat surface portion of the heat-receiving member, thereby supporting the heat-receiving member;
The second jig includes:
The annular pressing portion includes a plurality of pillar portions having a longitudinal direction in the axial direction of the annular pressing portion, and an annular fastening portion.
the pressing portion supports the thermoelectric conversion module by pressing the thermoelectric conversion module against the heat receiving member with the cooling member interposed therebetween;
The column portion of the first jig and the column portion of the second jig are disposed at positions where they do not interfere with each other;
A gap is provided between an outer surface of the fastening portion of the first jig and an inner surface of the fastening portion of the second jig,
The sealing member is
a flat surface of the heat-receiving member and an inner surface of the hook of the outer shell member;
By fastening the first jig to the outer shell member, the first jig, the sealing member, and the outer shell member are integrally constrained.
A thermoelectric conversion device comprising: 2. The thermoelectric conversion device according to claim 1, wherein an O-ring serving as the sealing member is disposed in a groove on the inner side of the hook portion of the outer shell member. 3. The thermoelectric converter according to claim 1, wherein the fin portion and a part of the outer shell member protrude into the heat source fluid.

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