Method for manufacturing thermoelectric power generation system

Abstract

To provide a thermoelectric power generation system having excellent efficiency of thermoelectric power generation.SOLUTION: A method for manufacturing a thermoelectric power generation system comprising a thermoelectric power generation module 2 in a duplex tube composed of an inner tube 1a and an outer tube 1b, the thermoelectric power generation module including P type thermoelectric elements 13 and N type thermoelectric elements 14 alternately arranged and mounted on a flexible substrate 11, the substrate having a plurality of slits 18 formed along a direction in which the P type thermoelectric elements and N type thermoelectric elements are serially connected, includes: a step of winding the thermoelectric power generation module around the inner tube while arranging the slits along an axial direction of the inner tube; and a step of inserting the inner tube around which the thermoelectric power generation module is wound into the outer tube, expanding the inner tube in the radial direction by applying pressure to the inside of the inner tube, and making the inner tube, the thermoelectric power generation module, and the outer tube adhere to one another.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a thermoelectric power generation system equipped with a heat exchanger formed of a double pipe. [Background technology]

[0002] In modern industrial society, a huge amount of waste heat, more than 60% of the total primary energy supply, is emitted into the global environment, mainly from factories, power plants, steel mills, automobiles, buildings, lighting, ships, etc., and it is estimated that more than 75% of this waste heat is discharged as wastewater or exhaust gas at temperatures below 250°C.

[0003] This waste heat is generally transported through exhaust heat pipes. Heat exchangers that exchange the heat of high-temperature gas flowing inside the pipe with cold water flowing outside the pipe, or conversely, heat exchangers that exchange the heat collected by a heat collector tube installed in the exhaust heat gas with cold water flowing in a pipe installed inside the heat collector tube, can cool the high-temperature gas, but it is difficult to reuse the heat exchanged with the cold water, which poses a challenge to energy conservation.

[0004] Patent Document 1 discloses a tubular heat exchanger with a thermoelectric power generation function, in which a flexible thermoelectric power generation module 110 is attached between the outside of a drainage pipe 100 through which high-temperature gas or hot water 100A flows and the inside of a cooling water pipe 120 through which cooling water 120A flows, as shown in Figure 7, and generates electricity by utilizing the temperature difference generated on both sides. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-267316 Summary of the Invention [Problem to be solved by the invention]

[0006] In the heat exchanger disclosed in Patent Document 1, the thermoelectric power generation module is directly cooled with water, so it is necessary to provide a waterproofing means, such as attaching a waterproof sheet to the thermoelectric power generation module. However, waterproof sheets and the like are made of resin, and providing such a waterproofing means causes heat loss, which poses a problem of reducing the power generation efficiency of the thermoelectric power generation module 110.

[0007] Furthermore, when a heat exchanger made up of double pipes is installed in the exhaust gas from a boiler or the like, the heat exchanger needs to have excellent pressure resistance and be highly reliable and leak-free so as not to adversely affect the boiler system. However, such high reliability has not been taken into consideration in the past for heat exchangers.

[0008] The present invention has been made in view of the above points, and a main object of the present invention is to provide a method for manufacturing a highly reliable thermoelectric power generation system that generates thermoelectric power with high efficiency. [Means for solving the problem]

[0009] The manufacturing method of the thermoelectric power generation system according to the present invention is a manufacturing method of a thermoelectric power generation system having a thermoelectric power generation module between a double tube consisting of an inner tube and an outer tube, in which the thermoelectric power generation module is mounted on a flexible substrate in an alternating arrangement of P-type thermoelectric elements and N-type thermoelectric elements, and the substrate has a plurality of slits formed in it along the direction in which the P-type thermoelectric elements and N-type thermoelectric elements are connected in series, and is characterized by comprising the steps of: winding the thermoelectric power generation module around the inner tube with the slits aligned with the axial direction of the inner tube; inserting the inner tube with the thermoelectric power generation module wrapped around it into the outer tube; and applying pressure inside the inner tube to expand the inner tube radially, thereby tightly adhering the inner tube, thermoelectric power generation module, and outer tube. [Effects of the Invention]

[0010] According to the present invention, the inner tube, thermoelectric power generation module, and outer tube are mounted in close contact with each other, which reduces heat transfer loss between the thermoelectric power generation module and the inner tube and / or outer tube, thereby ensuring a large temperature difference in the thermoelectric power generation module and improving the efficiency of thermoelectric power generation.

[0011] Furthermore, by wrapping elastic sheets between the inner tube and the thermoelectric power generation module and between the outer tube and the thermoelectric power generation module and then inserting the inner tube into the outer tube, even if there is a difference in thermal expansion between the inner tube and the outer tube in the radial direction, the difference in thermal expansion can be absorbed by the elastic sheets, thereby reducing stress on the thermoelectric power generation module, thereby achieving a highly reliable thermoelectric power generation system. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically showing the configuration of a thermoelectric power generation system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of a thermoelectric power generation module. [Figure 3] FIG. 10 is a cross-sectional view showing a modified example of the thermoelectric power generation system. [Figure 4] FIG. 1 is a perspective side view of a thermoelectric power generation system. [Figure 5] FIG. 1 is a diagram showing an example in which a thermoelectric power generation system is applied to a boiler. [Figure 6] FIG. 1 is a diagram showing an example in which a thermoelectric power generation system is installed in an organic solvent distillation, condensation, and recovery plant. [Figure 7] FIG. 1 is a perspective view showing the appearance of a conventional heat exchanger with a thermoelectric power generation function. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiment. Furthermore, appropriate modifications are possible within the scope of the effects of the present invention.

[0014] FIG. 1 is a diagram showing a schematic configuration of a thermoelectric power generation system according to one embodiment of the present invention, showing a cross section perpendicular to the axial direction of a double pipe constituting a heat exchanger.

[0015] 1, a thermoelectric power generation system 20 in this embodiment includes a heat exchanger 1 configured as a double pipe consisting of an inner pipe 1a and an outer pipe 1b. A thermoelectric power generation module 2 is installed between the inner pipe 1a and the outer pipe 1b. The thermoelectric power generation module 2 generates thermoelectric power using the temperature difference between the medium inside the inner pipe 1a and the medium outside the outer pipe 1b.

[0016] An elastic sheet 3a having elasticity is attached between the thermoelectric power generation module 2 and the inner tube 1a in a state of being in close contact with the thermoelectric power generation module 2 and the inner tube 1a. In addition, an elastic sheet 3b having elasticity is attached between the thermoelectric power generation module 2 and the outer tube 1b in a state of being in close contact with the thermoelectric power generation module 2 and the outer tube 1b.

[0017] According to this embodiment, the elastic sheets 3a, 3b are attached in close contact between the thermoelectric power generation module 2 and the inner tube 1a and outer tube 1b, thereby reducing heat transfer loss between the thermoelectric power generation module 2 and the inner tube 1a and outer tube 1b. This ensures a large temperature difference in the thermoelectric power generation module 2, thereby improving the efficiency of thermoelectric power generation.

[0018] Furthermore, because the elastic sheets 3a, 3b have elasticity, even if there is a difference in thermal expansion between the inner tube 1a and the outer tube 1b in the radial direction, the difference in thermal expansion can be absorbed by the elastic sheets 3a, 3b, thereby reducing stress on the thermoelectric power generation module 2. This makes it possible to realize a highly reliable thermoelectric power generation system.

[0019] In addition, the heat exchanger 1 is constructed with a double pipe consisting of an inner pipe 1a and an outer pipe 1b that are pressure-resistant, making it possible to realize a heat exchanger 1 that has excellent pressure resistance and is leak-free. This prevents adverse effects on the boiler system, even if the heat exchanger 1 is installed in the exhaust gas of a boiler, for example. While seamless pipes are preferred for the inner pipe 1a and the outer pipe 1b, pipes made by processing steel plates into a cylindrical shape and welding the seams may also be used.

[0020] The elastic sheets 3a and 3b may be made of any elastic material, such as a silicone sheet, a carbon sheet, or rubber with dispersed carbon nanotubes. The elastic sheets 3a and 3b are preferably made of a highly thermally conductive material. The elastic sheets 3a and 3b may be attached between the thermoelectric power generation module 2 and either the inner tube 1a or the outer tube 1b.

[0021] FIG. 2 is a diagram showing a specific configuration of the thermoelectric power generation module 2. As shown in FIG.

[0022] As shown in Fig. 2, wiring lands 12 are formed on a flexible base substrate 11, and P-type thermoelectric elements 13 and N-type thermoelectric elements 14 are mounted in an alternating arrangement on the wiring lands 12. The P-type thermoelectric elements 13 and N-type thermoelectric elements 14 are connected in series by a wiring layer 16 formed on a flexible upper wiring substrate 15. The thermoelectrically generated power is extracted from extraction electrodes 17.

[0023] A plurality of slits 18 are formed in the upper wiring substrate 15 along the direction in which the P-type thermoelectric elements 13 and the N-type thermoelectric elements 14 are connected in series. This makes it easier for the thermoelectric power generation module 2 to bend in a direction perpendicular to the slits 18. To configure a thermoelectric power generation system using such a thermoelectric power generation module 2, the thermoelectric power generation module 2 is wound around the inner tube 1a. At this time, by aligning the slits 18 with the axial direction of the inner tube 1a, the thermoelectric power generation module 2 can be easily attached to the inner tube 1a.

[0024] Specifically, the thermoelectric power generation system 20 shown in FIG. 1 is configured as follows: The inner tube 1a has an outer diameter of 25.4 mm, the thermoelectric power generation module 2 has an outer shape of 5 cm square and a thickness of 1.2 mm, and the seamless outer tube 1b has an outer diameter of 36 mm. The resilient sheets 3a and 3b are silicone sheets with a thermal conductivity of 4 W / mK and a thickness of 1 mm. From the viewpoint of heat resistance life, it is desirable to attach the resilient sheets 3a and 3b to at least the inner tube 1a or the outer tube 1b, whichever is the cooling side as the medium. Furthermore, the resilient sheet 3a can be made of a carbon sheet with high thermal conductivity (30 W / mK or higher) or rubber with carbon nanotubes dispersed therein to increase its thermal conductivity.

[0025] FIG. 3 is a diagram showing a modification of the thermoelectric power generation system 20 shown in FIG. 1, and shows a cross section perpendicular to the axial direction of the double pipe that constitutes the heat exchanger 1. In FIG.

[0026] 3, a thermoelectric power generation system 20 in this modification has the same configuration as the thermoelectric power generation system 20 shown in Fig. 1, except that a heat transfer sheet 4 with high thermal conductivity is inserted between the outer tube 1b and the elastic sheet 3b on the outside of the thermoelectric power generation module 2. This reduces the heat transfer loss between the thermoelectric power generation module 2 and the outer tube 1b, ensuring a large temperature difference in the thermoelectric power generation module 2 and increasing the efficiency of thermoelectric power generation.

[0027] The heat transfer sheet 4 may be made of any material with high thermal conductivity, such as metals with high thermal conductivity such as Cu or Al. If the heat transfer sheet 4 is made of a carbon sheet, the heat transfer sheet 4 can be easily inserted between the elastic sheet 3b and the outer tube 1b because the carbon sheet has high thermal conductivity (30 W / mK or more), can be made thin (0.1 mm or less), and has a low coefficient of friction with other materials.

[0028] In FIG. 3, the heat transfer sheet 4 is inserted between the outer elastic sheet 3b of the thermoelectric power generation module 2 and the outer tube 1b, but the heat transfer sheet 4 may also be inserted between the inner elastic sheet 3a of the thermoelectric power generation module 2 and the inner tube 1a, or may be inserted in both.

[0029] When the heat transfer sheet 4 is made of metal pipes, it is preferable to provide the heat transfer sheet 4 with a plurality of slits 5 extending in a direction perpendicular to the axial direction of the inner pipe 1a and the outer pipe 1b, as shown in Fig. 4. Here, Fig. 4 is a perspective view of the thermoelectric power generation system 20 as seen from a side parallel to the axial direction of the double pipes that make up the heat exchanger.

[0030] The heat transfer sheet 4 has multiple slits 5 in the axial direction, which gives it flexibility in the axial direction. As a result, even if there is a difference in thermal expansion between the inner tube 1a and the outer tube 1b in the axial direction, the difference in thermal expansion can be absorbed by the heat transfer sheet 4, thereby reducing stress on the thermoelectric power generation module 2. This makes it possible to realize a highly reliable thermoelectric power generation system.

[0031] Furthermore, if the heat transfer sheet 4 is made of a carbon sheet, the carbon sheet is flexible, so the difference in thermal expansion in the axial direction between the inner tube 1a and the outer tube 1b can be absorbed by the heat transfer sheet 4 even without providing a slit 5 in the heat transfer sheet 4.

[0032] To create a double-pipe heat exchanger that constitutes this thermoelectric power generation system 20, simply insert the inner pipe, including the heat transfer sheet 4, into the outer pipe 1b. When a carbon sheet is used for the heat transfer sheet 4, the carbon sheet has low friction with the outer pipe 1b, allowing for easy insertion even with small dimensional tolerances. It is essential to closely contact the inner pipe 1a, thermoelectric power generation module 2, heat transfer sheet 4, and outer pipe 1b to reduce heat transfer loss, increase the temperature difference in the thermoelectric power generation module 2, and increase the electromotive force of thermoelectric power generation. One possible method for achieving this is to apply high pressure to the inner pipe 1a to expand it radially, i.e., expand it. This method is particularly suitable for uniformly expanding long pipes, e.g., pipes longer than 1 m. This effectively ensures uniform power generation characteristics even when thermoelectric power generation modules are installed along a long pipe.

[0033] FIG. 5 is a diagram showing an example in which the thermoelectric power generation system 20 according to this embodiment is applied to a boiler.

[0034] 5, the boiler 40 mixes fuel with air supplied by a blower 41, burns the mixture in a burner 42, and generates steam using the heat of the combustion gas. The heat exchanger of the thermoelectric power generation system 20 is disposed in a flue 43 through which exhaust gas from the boiler 40 passes. One end of an inner pipe (not shown) of the heat exchanger is connected to a water pipe 45a through which water from a feedwater pump 44 passes, and the other end of the inner pipe is connected to a water pipe 45b that supplies water to the boiler 40.

[0035] That is, in the thermoelectric power generation system 20 arranged in the flue 43, the medium outside the outer tube (not shown) is boiler exhaust gas, and the medium inside the inner tube is boiler supply water. As a result, the thermoelectric power generation system 20 can perform thermoelectric power generation while providing an economizer function by preheating the boiler supply water inside the inner tube with the boiler exhaust gas outside the outer tube.

[0036] Furthermore, instead of disposing the heat exchanger of the thermoelectric power generation system 20 inside the flue 43 through which the exhaust gas from the boiler 40 passes, it may be disposed inside a recovery chamber that recovers water vapor or organic solvent vapor. In this case, the medium outside the outer tube is water vapor or organic solvent vapor, and the medium inside the inner tube is cooling water, and thermoelectric power generation can be performed while recovering water vapor or organic solvent vapor.

[0037] 6, a plurality of heat exchangers of the thermoelectric power generation system 20 may be bundled and arranged in an organic solvent distillation, condensation, and recovery plant 50. In this case, organic solvent vapor is caused to flow through an inner pipe (not shown) and the outside of an outer pipe (not shown) is cooled with water, so that thermoelectric power generation can be performed while the organic solvent vapor is condensed and recovered as a liquid.

[0038] For example, if toluene vapor (organic solvent vapor) with a vapor gas temperature of 110°C is passed through the inner tube, the outside of the outer tube is cooled with cooling water at 25°C, and thermoelectric power generation is performed while condensing the organic solvent vapor and recovering it as a liquid, a temperature difference of approximately 70°C can be obtained in the thermoelectric power generation module 2. [Explanation of symbols]

[0039] 1 heat exchanger 1a Inner tube 1b outer tube 2 Thermoelectric power generation module 3a, 3b Elastic sheet 4. Heat transfer sheet 5 Slits 11 Base board 12 Wiring land 13 P-type thermoelectric element 14 N-type thermoelectric element 15 Upper wiring board 16 wiring layer 17 electrodes 18 Slit 20 Thermoelectric power generation system 40 Boiler 41 Blower 42 Burner 43 Flue 44 Water Pump 45a, 45b water pipe 50 Distillation Condensation Recovery Plant

Claims

1. A method for manufacturing a thermoelectric power generation system having a thermoelectric power generation module between a double tube consisting of an inner tube and an outer tube, comprising: The thermoelectric power generation module is mounted on a flexible substrate in such a manner that P-type thermoelectric elements and N-type thermoelectric elements are alternately arranged, a plurality of slits are formed in the substrate along a direction in which the P-type thermoelectric elements and the N-type thermoelectric elements are connected in series; winding the thermoelectric power generation module around the inner tube with the slit aligned with the axial direction of the inner tube; inserting the inner tube, with the thermoelectric power generation module wound around it, into the outer tube, and applying pressure to the inside of the inner tube to expand the inner tube in a radial direction, thereby bringing the inner tube, the thermoelectric power generation module, and the outer tube into tight contact with each other; A method for manufacturing a thermoelectric power generation system comprising:

2. 2. The method for manufacturing a thermoelectric power generation system according to claim 1, wherein in the step of inserting the inner tube into the outer tube, the inner tube is inserted into the outer tube with elastic sheets wrapped between the inner tube and the thermoelectric power generation module and between the outer tube and the thermoelectric power generation module.

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