JPH08130331A - Thermoelectric converter - Google Patents

Abstract

(57) [Summary] [Object] To provide a thermoelectric conversion device for converting heat of a heat transfer tube into electricity while preventing damage to the thermoelectric conversion element due to thermal stress. A heat transfer tube having a fluid flowing therein and a thermoelectric conversion element arranged so as to surround the heat transfer tube, an outer peripheral surface of the heat transfer tube, and an inner surface of the thermoelectric conversion element facing the outer peripheral surface. A gap was formed between them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric conversion device for directly converting heat energy into electric energy by using a thermoelectric conversion element having a thermoelectric effect such as Seebeck effect or Peltier effect, and particularly to surround a heat transfer tube. The present invention relates to a thermoelectric conversion device in which a thermoelectric conversion element is arranged.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Laid-Open No. 2-151087, thermoelectric conversion elements are alternately arranged in a ring shape outside a heat transfer tube and electrically connected in series.

In addition, "cluster ion beam (IC
Amorphous FeS as a new type thermoelectric material by method B)
Production of i ₂ thin film ”Proceedings of the 6th International Conference on Thermoelectric Energy Conversion 1986 Matsubara, Takagi et al. (“ AMORPHOUS FeSi ₂ FIL
MS AS A NEW THERMOELECTRIC MATERIAL PREPARED BY ION
IZED-CLUSTER BEAM (ICB) TECHNIQUE ”Proc.6th Int.C
onf.Thermoelectric Energy Convers, 1986 K. Matsubar
a, T. Takagi et al. ), Thermoelectric conversion elements were formed on both sides of a ring-shaped insulating plate, and a thermoelectric conversion element module having electrodes inside and outside the ring was joined to a pipe.

[0004]

However, in the conventional thermoelectric conversion device in which a ceramic thermoelectric conversion element having a small linear expansion coefficient and a metal tube having a large linear expansion coefficient are directly joined, the thermoelectric conversion element is caused by thermal stress. Was sometimes damaged. In order to prevent the damage of the thermoelectric conversion element, if the temperature difference of the heat source is made small and the thermal expansion of the heat transfer tube is suppressed to be small by making the heat transfer tube small, the thermoelectromotive force is lowered.

Further, as shown in JP-A-62-189774, it is necessary to provide a movable protective plate around the thermoelectric conversion element in order to reduce the thermal stress, so that the transmission of a circular tube having a wide range of application is possible. Not applicable to heat tubes.

The range of use of these conventional thermoelectric converters is limited by the structure and use conditions.

An object of the present invention is to provide a thermoelectric conversion device for converting the heat of a heat transfer tube into electricity, which can reduce the probability of breakage of the thermoelectric conversion element due to thermal stress.

Another object of the present invention is to provide a thermoelectric conversion device capable of further increasing thermoelectric conversion efficiency.

Another object of the present invention is to provide a thermoelectric conversion device applicable to various heat source fluids.

[0010]

The features of claim 1 for attaining the above object of the present invention include a heat transfer tube and a thermoelectric conversion element arranged so as to surround the heat transfer tube, and the outer circumference of the heat transfer tube. A gap is formed between the surface and the inner surface of the thermoelectric conversion element.

In order to achieve the above-mentioned object of the present invention, the feature of claim 2 is that a heat transfer tube, a thermoelectric conversion element arranged so as to surround the outside of the heat transfer tube, and an insulation provided between adjacent thermoelectric conversion elements. It is provided with a body, a conductive member that connects the adjacent thermoelectric conversion elements, and thermoelectric conversion element support means that supports the thermoelectric conversion elements from the outer peripheral surface.

A third aspect of the present invention which achieves the other object of the present invention.
Is characterized by comprising a heat transfer tube and a thermoelectric conversion element arranged so as to surround the heat transfer tube, forming a gap between the outer peripheral surface of the heat transfer tube and the inner surface of the thermoelectric conversion element, The heat medium is enclosed. A fourth aspect of the present invention, which achieves the other object of the present invention, is that the heat medium is an electrically insulating material.

According to another aspect of the present invention, there is provided another object.
The feature of (1) is that it includes means for moving the heat medium into and out of the gap according to an increase or decrease in the width of the gap in the radial direction.

The feature of claim 6 for achieving the above-mentioned object of the present invention is that the first heat transfer tube, the second heat transfer tube surrounding the first heat transfer tube, the first heat transfer tube and the second heat transfer tube. A thermoelectric conversion element arranged so as to surround the first heat transfer tube between the heat transfer tube, between the outer peripheral surface of the first heat transfer tube and the inner surface of the thermoelectric conversion element, the first A gap is formed, and a second gap is formed between the outer peripheral surface of the thermoelectric conversion element and the inner surface of the second heat transfer tube.

[0015]

According to the first aspect of the invention, when the fluid as the heat source flows in the heat transfer tube and the thermoelectric conversion element arranged so as to surround the heat transfer tube converts the heat of the heat transfer tube into electricity, In the gap formed between the outer peripheral surface of and the inner surface of the thermoelectric conversion element facing the outer peripheral surface, even if the outer peripheral surface of the heat transfer tube moves due to thermal expansion, the heat transfer tube and the thermoelectric conversion element do not contact. The probability of damage to the thermoelectric conversion element due to thermal stress can be reduced.

According to the second aspect of the invention, when the fluid as the heat source flows in the heat transfer tube and the thermoelectric conversion element electrically connected in series by the conductive member converts the heat of the heat transfer tube into electricity. Since the thermoelectric conversion element supporting means fixed to the outer circumference of the heat transfer tube supports the thermoelectric conversion element from the outer peripheral surface of the heat transfer tube, the outer surface of the heat transfer tube and the inner surface of the thermoelectric conversion element facing the outer peripheral surface are. Since a gap is formed in the gap, and even if the outer peripheral surface of the heat transfer tube moves in the gap due to thermal expansion, the heat transfer tube and the thermoelectric conversion element do not come into contact with each other, so that the probability of damage to the thermoelectric conversion element due to thermal stress can be reduced.

According to the third aspect of the present invention, the same action as in the first aspect is produced, and the gap can be filled with the heat medium, so that the heat transfer between the heat transfer tube and the thermoelectric conversion element is increased. Therefore, the thermoelectric conversion efficiency can be further increased.

According to the fourth aspect of the present invention, the same effect as that of the third aspect of the present invention can be obtained, and the electrically insulating heat medium provides insulation between the heat transfer tube and the thermoelectric conversion element. Since the layer is formed and the insulating property is further enhanced, a conductive fluid can be used as a heat source, and it can be applied to various heat source fluids.

According to the invention of claim 5, the same action as that of the invention of claim 3 is obtained, and when the width of the gap becomes narrow due to thermal expansion of the heat transfer tube, the width of the gap in the radial direction is reduced. The means for moving the heat medium in and out of the gap according to the increase and decrease prevents the pressure inside the gap from rising due to the accommodation of the heat medium from the gap, so that the probability of breakage of the thermoelectric conversion element can be further reduced, and the gap due to contraction of the heat transfer tube. If the width of the heat medium becomes wider, the means for moving the heat medium into and out of the gap supplies the heat medium to the gap, so that the heat transfer between the heat transfer tube and the thermoelectric conversion element is increased and the thermoelectric conversion efficiency is increased. Will increase.

According to the sixth aspect of the present invention, a fluid as a heat source flows in the first heat transfer tube, and the second heat transfer tube that surrounds the thermoelectric conversion element is arranged so as to surround the first heat transfer tube. Fluids of different temperatures that are heat sources flow, and when the thermoelectric conversion element converts the temperature difference into electricity, it is formed between the outer peripheral surface of the first heat transfer tube and the inner surface of the thermoelectric conversion element facing the outer peripheral surface. In the first gap, even if the outer peripheral surface of the first heat transfer tube moves due to thermal expansion, and the outer peripheral surface of the thermoelectric conversion element and the inner surface of the second heat transfer tube facing the outer peripheral surface of the thermoelectric conversion element. In the second gap formed between, even if the inner surface of the second heat transfer tube moves due to thermal expansion, since the first heat transfer tube and the second heat transfer tube and the thermoelectric conversion element are not in contact with each other, The probability of breakage of the thermoelectric conversion element due to thermal stress can be reduced.

[0021]

【Example】

(Embodiment 1) Hereinafter, a thermoelectric conversion device according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a vertical cross-sectional view (cross-sectional view in the axial direction) of the thermoelectric conversion device of this embodiment.

In the thermoelectric conversion device of this embodiment, the fluid of the high temperature heat source is passed inside the heat transfer tube.

On the outer surface of the heat transfer tube 10, a thin film 11 of a substance having a high electrical insulation property (for example, Al ₂ O ₃ ) is formed.

The ring of the thermoelectric conversion element obtained by joining a part of the inside of the ring-shaped N-type element 1 and the ring-shaped P-type element 2 with the insulator ring 3 sandwiched therebetween is called the thermoelectric element module 4. Call. The connection between the N-type element 1 and the P-type element 2 is located between the insulator ring 3 and the thin film 11. The plurality of thermoelectric element modules 4 surround the heat transfer tube 10 to surround the heat transfer tube 10.
Are arranged in the axial direction of. A ring-shaped insulator ring 7 is arranged between the thermoelectric element modules 4.

The ring-shaped electrode ring 8 is the insulator ring 7.
The N-type element 1 and the P-type element 2 which are adjacent to each other are covered over the entire circumference by way of, and the central axes of the insulator ring 7 and the thermoelectric element module 4 are aligned. The N-type element 1 and the P-type element 2 of the adjacent thermoelectric element modules 4 are electrically connected by the electrode ring 8. The electrode ring 8 located at one end of the assembly of the thermoelectric element modules 4 electrically connected in this way is connected to the lead wire 9, and the electrode ring 8 located at the other end is connected to the lead wire (not shown). To be done.

Assembly of thermoelectric element module 4 and heat transfer tube 1
Ring-shaped end plates 30 are attached to both ends of 0, respectively. The small diameter side of the end plate 30 is welded to the heat transfer tube 10, and the large diameter side thereof is welded to the electrode ring 8. The difference between the outer diameter and the inner diameter of the end plate 30,
That is, the height from the heat transfer tube 10 is larger than the length from the inner surface of the thermoelectric element module 4 to the outer surface of the electrode ring 8. Therefore, in such a configuration, the end plate 30 supports the thermoelectric element module 4 from the heat transfer tube 10 and forms the gap 5.

The heat transfer tube 10 is usually made of metal such as copper, stainless steel, and aluminum alloy. The linear expansion coefficient of metal is 1.5 × 10
^-5 [1 / K] value. For example, when the temperature rises at 300 ° C, these metals have a diameter of 0.5% due to thermal expansion.
Increase. When the radius of the heat transfer tube 10 is 20 mm, the change in radius due to thermal expansion is 0.1 mm. However, since the material of the thermoelectric conversion element is ceramics such as iron silicide and the coefficient of linear expansion is very small, the thermoelectric conversion element keeps almost the same shape even if the temperature changes. Therefore, in the present embodiment, the difference between the inner diameter of the ring-shaped thermoelectric element module 4 and the outer diameter of the heat transfer tube 10 at room temperature is set so that the thermoelectric element module 4 is not damaged by the thermal expansion of the heat transfer tube 10 in the radial direction. That is, the width in the radial direction of the gap 5 formed between the heat transfer tube 10 and the thermoelectric element module 4 is made larger than the amount of change in the radius of the heat transfer tube 10 due to thermal expansion.

The gap 5 is filled with a liquid heat medium 6 (for example, insulating oil used for a transformer or lubricating oil having a high heat resistance used for machine parts). The heat medium 6 is injected from the heat medium supply pipe 31 attached to the end plate 30. After the injection of the heating medium, the valve 32 is closed.

At the end of the heat transfer tube 10, that is, between the end plate 30 and the insulator ring 7 located closest to the end plate 30,
There is a volume changing device 40 and a liquid chamber 43 for the heat medium 6.
The volume changing device 40 provided in the liquid chamber 43 is used for the heat transfer tube 1
It absorbs the movement of the heat medium due to the volume change of the gap 5 due to the thermal expansion of 0. The volume changing device 40 includes a piston 41 and a spring 42 that presses the piston 41. Piston 4
The height of 1 is larger than the width of the gap 5. The liquid chamber 43 and the volume changing device 40 are provided at four positions at the end of the heat transfer tube 10 as in the case shown in FIG. 9.

The movement of the outer surface of the heat transfer tube 10 when the fluid of the high temperature heat source is caused to flow inside the heat transfer tube 10 of this embodiment will be described with reference to FIG. FIG. 2 is an enlarged view of a part of the vertical cross section of FIG.

By flowing a high-temperature fluid inside the heat transfer tube 10, the outer surface of the heat transfer tube 10 which was at the position A at room temperature moves to the position B due to thermal expansion. However, since the amount of change in the radial direction of the heat transfer tube 10 due to thermal expansion is smaller than the original width of the gap 5 in the radial direction, the heat transfer tube 10
The outer surface of the thermoelectric element module 4 does not contact.

Then, the heat medium 6 filled in the gap 5 is pushed out to the liquid chamber 43 at the end by the amount of decrease in the volume of the gap 5 due to the movement of the outer surface of the heat transfer tube 10 to the outside. The heat medium 6 pushes the piston 41 toward the electrode ring 8 to increase the volume of the liquid chamber 43. The force of the spring 42 pressing the piston 41, which is compressed by the movement of the piston 41 toward the electrode ring 8 side, balances the pressure of the heat medium 6. Since the volume changing device 40 can prevent an abnormal increase in the pressure in the gap 5 due to the decrease in the volume of the gap 5, the thermal stress on the thermoelectric element module 4 by the heat medium 6 can be reduced.

When the temperature of the fluid flowing in the heat transfer tube 10 decreases and the outer surface of the heat transfer tube 10 moves toward the center of the heat transfer tube 10 due to contraction and the width of the gap 5 increases, the spring 42 causes the piston 41 to move. To the center of the heat transfer tube 10 to move the liquid chamber 43
The heat medium 6 inside is supplied into the gap 5.

Even if the volume of the gap 5 is increased as described above,
Since the gap 5 is filled with the heat medium 6 by the volume changing device 40, the loss of heat transferred between the heat transfer tube 10 and the thermoelectric element module 4 is less, and the thermoelectric conversion efficiency can be made higher. Since a high-temperature fluid flows inside the heat transfer tube 10 and the outside of the electrode ring 8 is in contact with a liquid whose temperature is lower than that of the fluid, a temperature gradient occurs inside the thermoelectric element module 4. Therefore, thermoelectromotive force is generated, and a potential difference is generated between the lead wire 9 at one end and the lead wire (not shown) at the other end.

According to the heat transfer tube 10 including the thermoelectric element module 4 of this embodiment, the following effects can be obtained.

(1) Heat transfer tube 10 and thermoelectric element module 4
By providing the gap 5 between and, the thermal stress to the thermoelectric element module 4 due to the thermal expansion of the heat transfer tube 10 can be reduced,
The damage probability of the thermoelectric conversion element can be significantly reduced.

(2) By filling the space 5 with the heat medium 6, heat loss between the heat transfer tube 10 and the thermoelectric element module 4 is further reduced, so that the thermoelectric conversion efficiency can be further increased.

(3) Since the volume changing device 40 can fill the gap 5 with the heat medium 6 even when the width of the gap 5 is expanded, the thermoelectric conversion efficiency can be further increased. Further, since the volume changing device 40 can prevent the pressure in the gap 5 from abnormally increasing due to the decrease in the volume of the gap 5,
The thermal stress on the thermoelectric element module 4 due to the heat medium 6 can be reduced. Thereby, the damage probability of the thermoelectric conversion element can be further reduced. Further, if the electrically insulating heat medium 6 is used, the space 5 is always filled with the heat medium 6 by the volume changing device 40, and the insulation between the thermoelectric element module 4 and the heat transfer tube 10 is further enhanced. A conductive fluid can be passed through the heat transfer tube 10 as a high temperature heat source.

(Embodiment 2) A thermoelectric conversion device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 3 is a vertical cross-sectional view of the thermoelectric conversion device of this embodiment.

In this embodiment, as in the first embodiment, the heat transfer tube 1
A high temperature heat source is supplied within 0.

In this embodiment, the thermoelectric element module 4 has a small-diameter seal ring 16 and a large-diameter insulator ring 7b on the outer side of the heat transfer tube 10 so that a gap 5 similar to that of the first embodiment is formed. A plurality of are arranged through. The seal ring 16 is an elastic body and can extend radially within elastic limits.

Similar to the first embodiment, each end plate 30 is provided. The small diameter side of the end plate 30 is welded to the heat transfer tube 10, and the large diameter side thereof is welded to the electrode ring 8.

In this embodiment, an elastic member 5 such as a spring is provided between the end plate 30 and the insulator ring 7b closest to the end plate 30.
A length adjusting device 50 consisting of 1 is provided. In the length adjusting device 50, the elastic body 51 pushes the insulator ring 7b at the end portion, so that the thermoelectric element module 4 and the insulator ring 7 are joined together.
The connection with b and the contact between the thermoelectric element module 4 and the seal ring 16 are maintained.

Another structure of this embodiment is the volume changing device 40.
Example 1 is the same as Example 1 except that is not provided.

When the fluid of the high temperature heat source is supplied into the heat transfer tube 10 placed at room temperature, the gap 5 is formed as in the first embodiment.
Since the outer surface of the heat transfer tube 10 moves inside due to thermal expansion,
The outer surface of the heat transfer tube 10 does not contact the thermoelectric element module 4.

As the outer surface of the heat transfer tube 10 moves outward, the pressure-increasing heat medium 6 pushes the seal ring 16 in the radial direction of the heat transfer tube 10 and increases the inner diameter of the seal ring 16. The seal ring 16 is an elastic body.

When the temperature of the fluid in the heat transfer tube 10 decreases and the outer surface of the heat transfer tube 10 moves inward due to contraction to expand the width of the gap 5, the pressure in the gap 5 decreases. Since the seal ring 16 expands inward, the heat medium 6 existing between the adjacent thermoelectric element modules 4 is pushed out into the widened gap 5.

Even if the width of the gap 5 in the radial direction changes, the contraction or expansion of the seal ring 16 reduces the loss of heat transferred between the heat transfer tube 10 and the thermoelectric element module 4, thus improving the thermoelectric conversion efficiency. Can be higher.

Further, when the fluid of the high temperature heat source is flown through the heat transfer tube 10, the heat transfer tube 10 is thermally expanded in the axial direction. Due to the axial thermal expansion of the heat transfer tube 10, even if the distance between the thermoelectric element module 4 and the end plate 30 increases, the length adjusting device 50 is always provided.
Since the elastic body 51 constantly pushes the insulator ring 7b at the end, the connection between the thermoelectric element module 4 and the insulator ring 7b and the contact between the thermoelectric element module 4 and the seal ring 16 are maintained. As a result, the heat medium 6 does not leak from the gap 5.

Then, as in the first embodiment, thermoelectromotive force is generated inside the thermoelectric element module 4, and the lead wire 9 at one end is formed.
And a potential difference occurs between the lead wire (not shown) at the other end.

According to this embodiment, the effect (1) of the first embodiment is obtained.
In addition to obtaining the same effect as (2) and (2), the following effect can be obtained.

(1) Since the seal ring 16 can always fill the gap 5 with the heat medium 6, the thermoelectric conversion efficiency can be further increased.

(2) The length adjusting device 50 maintains the connection between the thermoelectric element module 4 and the insulator ring 7b, and the heat medium 6
Since the leakage from the gap 5 is prevented, the gap 5 is always filled with the heat medium 6, and the thermoelectric conversion efficiency can be further increased.

(Embodiment 3) A thermoelectric conversion device according to Embodiment 3 of the present invention will be described with reference to FIGS. 4 and 5.

In this embodiment, as in the first embodiment, the heat transfer tube 1
A high temperature heat source fluid is supplied to the inside of 0.

In this embodiment, the plurality of thermoelectric element modules 4 are arranged outside the heat transfer tube 10 so as to form a gap 5 between the thermoelectric element module 4 and the heat transfer tube 10 as in the second embodiment. The small-diameter seal ring 16b and the large-diameter insulator ring 7b are arranged between the adjacent thermoelectric element modules 4.

The thermoelectric element module 4 of this embodiment has an inclined surface formed by removing a portion of one end surface thereof which comes into contact with the seal ring 16b. The seal ring 16b is an elastic body. It can extend radially within elastic limits. The seal ring 16b has six protrusions that are in contact with the heat transfer tube 10 inside. The number of protrusions may be three or more.

This example is different from Example 2 except that the thermoelectric element module 4 having an inclined surface and the seal ring 16b are omitted.
It has the same structure as.

When a fluid of a high temperature heat source is flown through the heat transfer tube 10 placed at room temperature, the outer surface of the heat transfer tube 10 moves due to thermal expansion. However, like the first embodiment, since the outer surface moves within the gap 5, the outer surface of the heat transfer tube 10 does not come into contact with the thermoelectric element module 4.

Due to the movement of the outer surface of the heat transfer tube 10, the heat medium 6 pushes the seal ring 16b in the radial direction to increase the diameter of the seal ring 16b. Similar to the seal ring 16 of the second embodiment, the seal ring 16b pushes the heat medium 6 with the elastic force to balance the heat medium 6.

The temperature of the fluid inside the heat transfer tube 10 decreases,
When the outer surface of the heat transfer tube 10 moves due to contraction and the width of the gap 5 expands, the seal ring 16b pushes out the heat medium 6 and supplies it to the expanded gap 5, and the protrusion of the seal ring 16b causes the heat transfer tube to project. Press 10 to keep the gap 5 constant circumferentially.

Even if the width of the gap 5 changes, the heat medium 6 is always filled with the seal ring 16b, so that the heat transfer tube 1
The heat of the outer surface of 0 is efficiently transferred to the inner surface of the thermoelectric element module 4.

When the heat transfer tube 10 thermally expands in the axial direction, the length adjusting device 50 pushes the thermoelectric element module 4 to maintain the shape of the assembly of the thermoelectric element modules 4 as in the second embodiment.

When a temperature gradient is generated inside the thermoelectric element module 4, a thermoelectromotive force is generated as in the first embodiment, and the lead wire 9 at one end and the lead wire (not shown) at the other end are generated. A potential difference is generated between the two.

According to this embodiment, (1) of the first embodiment,
The same effects as (2) and (2) of Example 2 can be obtained, and the following effects can be obtained.

(1) The seal ring 16b achieves the same effect as the effect (1) of the second embodiment, and since the width of the gap 5 is kept constant in the circumferential direction by the projection, the heat transfer tube 1
0 and the thermoelectric element module 4 can be kept in non-contact with each other to further reduce the probability of breakage of the thermoelectric conversion element. Furthermore, from the outer surface of the heat transfer tube 10 to the thermoelectric element module 4,
The heat conduction becomes uniform in the circumferential direction, and the thermoelectric conversion efficiency can be further increased.

(Embodiment 4) A thermoelectric conversion device according to Embodiment 4 of the present invention will be described with reference to FIGS. 6, 7 and 8.

The thermoelectric conversion device of the present embodiment is one in which the thermoelectric element module 4 is incorporated in the annular portion of the double circular tube, and the fluid of the high temperature heat source is placed inside the inner heat transfer tube and the fluid inside the outer heat transfer tube is placed inside. A low temperature heat source fluid is supplied and used.

Similar to the first embodiment, the present embodiment focuses on the heat transfer tube 10 having the insulating thin film 11 formed on the outer surface,
A plurality of thermoelectric element modules 4 are arranged in the axial direction with an insulating ring 7 interposed therebetween so as to form a gap 5 a between the thermoelectric element 10 and the heat transfer tube 10. Similar to the first embodiment, adjacent thermoelectric element modules 4 are electrically connected in series by the electrode ring 8. A lead wire 9 is connected to the electrode ring 8 at one end, and a lead wire (not shown) is connected to the electrode ring 8 at the other end.

Heat transfer tube 2 provided with an insulating thin film 21 on the inner surface
0 is provided so as to surround the assembly of thermoelectric element modules 4. A gap 5b similar to the gap 5a is formed between the thermoelectric element module 4 and the heat transfer tube 20.

Similar to the first embodiment, the thermoelectric element module 4 has a volume changing device 40 for absorbing movement of the liquid heat medium 6 due to thermal expansion in the radial direction of the heat transfer tube 10, and the other end. In the same manner as the second embodiment, a length adjusting device 50 that absorbs thermal expansion in the axial direction is provided in the. As shown in FIG. 10, the elastic body 51 of the length adjusting device 50 has a ring shape extending over one circumference. The elastic body 51 provided between the end plate 30 at one end and the insulating ring 7 is in close contact with the end plate 30 and the insulating ring 7, and maintains the gaps 5a and 5b independently.

At both ends of the assembly of the thermoelectric element modules 4 and the heat transfer tubes 10 and 20, the ring-shaped end plates 3 are provided.
0 is attached respectively. The small diameter side of the end plate 30 is joined to the heat transfer tube 10, and the large diameter side of the end plate 30 is joined to the heat transfer tube 20.

The gap 5a and the gap 5b are independently connected to the volume changing device 40 at one end and the length adjusting device 50 at the other end, respectively. The gaps 5a and 5b are filled with the heat medium 6 which is a liquid, respectively. The heat medium 6 is injected from the supply pipes 31 and 31A provided in the end plate 30. After injecting the heat medium 6, the valves 32 and 32A are closed.

A plurality of thermoelectric converters of this embodiment are used in combination of a plurality of the thermoelectric converters of this embodiment as heat transfer tubes of a shell-and-tube type heat exchanger in parallel, or a unit length. It is also possible to use them by connecting them in series. When the thermoelectric conversion devices of this embodiment are connected in series, for example, the end plate 30 may be replaced with a flange-shaped or connection joint-shaped end plate.

A high temperature fluid is flown into the heat transfer tube 10 and a low temperature fluid is flown into the heat transfer tube 20 from the nozzle 22.

Even if the outer surface of the heat transfer tube 10 moves due to thermal expansion, the outer surface of the heat transfer tube 10 moves within the gap 5a as in the first embodiment, so that the outer surface of the heat transfer tube 10 and the thermoelectric element module 4 are separated from each other. There is no contact. Similarly, even if the inner surface of the heat transfer tube 20 moves due to thermal expansion, the inner surface of the heat transfer tube 20 moves within the gap 5b, so that the inner surface of the heat transfer tube 20 does not come into contact with the thermoelectric element module 4.

Similar to the first embodiment, even if the sizes of the gaps 5a and 5b change, the heat medium 6 is always filled in the gaps by the volume changing devices 40a and 40b.

When the heat transfer tube 10 is thermally expanded in the axial direction, the elastic body 51 of the length adjusting device 50 is used as in the second embodiment.
Pushes the insulator ring 7 at the end to maintain the connection between the thermoelectric element module 4 and the insulator ring 7b and prevent the heat medium 6 from leaking from the gap 5, so that the heat medium 6 is always kept in the gap 5. It is satisfied, and the thermoelectric conversion efficiency can be made higher. The elastic body 51 of the length adjusting device 50 has a ring shape that is continuous over the entire circumference, and has the thermoelectric element module 4 at one end.
Are provided along with to keep the gap 5a and the gap 5b independent.

When a temperature gradient is generated inside the thermoelectric element module 4, a thermoelectromotive force is generated as in the first embodiment, and the lead wire 9 at one end and the lead wire (not shown) at the other end are generated. A potential difference is generated between the two.

According to the present embodiment, the effect (1) of the first embodiment,
The same effects as (2), (3) and (2) of the second embodiment can be obtained, and the following effects can be obtained.

(1) If the temperature difference between the heat source fluids passing through the two heat transfer tubes 10 and 20 is increased, the temperature gradient inside the thermoelectric element module 4 can be increased. The conversion efficiency can be increased.

Further, as shown in FIG. 11, each end plate 30 provided in the heat transfer tube of this embodiment is provided with supply pipes 31 and 31A, respectively, and the supply pipes 31 and 31A are provided outside. If it is connected to (not shown), the heat medium 6 suitable for use conditions can be exchanged.

(Embodiment 5) A thermoelectric conversion device according to Embodiment 5 of the present invention will be described with reference to FIG.

In the thermoelectric conversion device of this embodiment, the gas of the high temperature heat source flows to the outside at right angles to the thermoelectric conversion device, the low temperature fluid flows in the heat transfer tube 10, and the high temperature gas is cooled to the outside of the electrode ring 8. It flows in a direction perpendicular to the direction of fluid flow.

In this embodiment, fins 18 are provided outside the electrode ring 8 in the second embodiment. The other configuration of this embodiment is the same as that of the second embodiment.

In general, the heat transfer coefficient of the gas is smaller than that of the liquid, that is, the heat resistance is large, so that the heat conduction from the gas of the high temperature heat source to the thermoelectric element module 4 is small. Therefore, a fin 18 for heat recovery is provided on the gas side electrode ring 8 to increase the effective heat transfer area outside the thermoelectric element module 4. The heat conduction from the gas of the high temperature heat source to the thermoelectric element module 4 is increased by the action of the fins 18. Therefore, since the temperature gradient inside the thermoelectric element module 4 becomes large, the thermoelectric element module 4 generates a larger thermoelectromotive force, and the heat conversion efficiency can be made higher.

According to the present embodiment, the effect (1) of the first embodiment,
The same effects as (2) and (3) can be obtained, and the following effects can be obtained.

(1) Since the fins 18 can increase the heat conduction from the gas of the high temperature heat source having a large heat resistance, the heat conversion efficiency can be further increased.

[0089]

According to the first aspect of the invention, the probability of breakage of the thermoelectric conversion element due to thermal stress can be reduced.

According to the second aspect of the present invention, the probability of breakage of the thermoelectric conversion element due to thermal stress can be further reduced.

According to the third aspect of the present invention, it is possible to prevent the thermoelectric conversion element from being damaged by thermal stress and to further improve the thermoelectric conversion efficiency.

According to the invention of claim 4, the same effect as that of the invention of claim 3 can be obtained, and the invention can be applied to various heat source fluids.

According to the invention of claim 5, the same effect as that of the invention of claim 3 can be obtained, the probability of breakage of the thermoelectric conversion element due to thermal stress can be further reduced, and the thermoelectric conversion efficiency can be further increased. can do.

According to the sixth aspect of the invention, the probability of breakage of the thermoelectric conversion element due to thermal stress can be reduced.

[Brief description of drawings]

FIG. 1 is a radial cross-sectional view of a thermoelectric conversion device, which is a preferred embodiment of the present invention.

FIG. 2 is an explanatory diagram showing movement of a heat transfer tube 10 in FIG. 1 in a radial direction.

FIG. 3 is a radial cross-sectional view of another embodiment of the present invention.

FIG. 4 is a sectional view taken along line VV of FIG.

FIG. 5 is a radial cross-sectional view of another embodiment of the present invention.

FIG. 6 is a radial cross-sectional view of another embodiment of the present invention.

FIG. 7 is a perspective view of the thermoelectric generator of FIG.

8 is a local enlarged view of the thermoelectric generator of FIG.

9 is a sectional view taken along line IX-IX in FIG.

10 is a sectional view taken along line XX of FIG.

FIG. 11 is a radial cross-sectional view of another embodiment of the present invention.

FIG. 12 is a radial cross-sectional view of another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... N-type element, 2 ... P-type element, 3, 7, 7b ... Insulator ring, 4 ... Thermoelectric element module, 5, 5a, 5b ... Void, 6, 6a, 6b ... Liquid heat medium, 8 ... Electrode ring , 9
... Lead wire, 10, 20 ... Heat transfer tube 11, 21, ... Insulating thin film, 15 ... Fin, 16, 16b ... Seal ring, 2
2 ... Nozzle, 30 ... End plate, 31, 31A ... Heat medium supply pipe, 32 ... Valve, 40, 40a, 40b ... Volume changing device, 41 ... Piston, 42 ... Spring, 43 ... Liquid chamber, 50 ...
Length adjusting device, 51 ... Elastic body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Harumi Wakana 7-2-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Energy Research Laboratory

Claims (6)

[Claims] 1. A heat transfer tube having a heat transfer tube therein and a thermoelectric conversion element arranged so as to surround the heat transfer tube, wherein the outer peripheral surface of the heat transfer tube and the thermoelectric conversion element facing the outer peripheral surface. A thermoelectric conversion device, wherein a gap is formed between the thermoelectric conversion device and the inner surface. 2. A heat transfer tube through which a fluid flows, a thermoelectric conversion element arranged so as to surround the outside of the heat transfer tube, an insulator arranged between adjacent thermoelectric conversion elements, and the adjacent thermoelectric conversion element. A thermoelectric conversion device comprising: a conductive member that connects elements and a thermoelectric conversion element supporting means that is fixed to the outer peripheral surface of the heat transfer tube and supports the thermoelectric conversion element from the outer peripheral surface. 3. A heat transfer tube including a heat transfer tube in which a fluid flows, and a thermoelectric conversion element arranged so as to surround the heat transfer tube, wherein the outer peripheral surface of the heat transfer tube and the thermoelectric conversion element facing the outer peripheral surface. A thermoelectric conversion device characterized in that a gap is formed between the inner surface and the inner surface, and a heat medium is enclosed in the gap. 4. The thermoelectric conversion device according to claim 3, wherein the heating medium is an electrically insulating substance. 5. The thermoelectric conversion device according to claim 3, further comprising means for moving the heat medium into and out of the gap according to an increase or decrease in a width of the gap in the radial direction. 6. A first heat transfer tube in which a fluid flows, a second heat transfer tube surrounding the first heat transfer tube and having an outer peripheral surface in contact with a fluid having a temperature different from that of the fluid, and a first heat transfer tube. A thermoelectric conversion element arranged so as to surround the first heat transfer tube between the second heat transfer tube, between the outer peripheral surface of the first heat transfer tube and the inner surface of the thermoelectric conversion element. A thermoelectric conversion device, wherein a first gap is formed, and a second gap is formed between the outer peripheral surface of the thermoelectric conversion element and the inner surface of the second heat transfer tube.