JP2013165240A - Thermoelectric conversion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a thermoelectric conversion system with large capacity that does not require a large place by integrating many thermoelectric conversion modules with a simple structure, to arrange the many thermoelectric conversion modules in one large-sized sealed space, and further to increase output density by increasing substantial arrangement density.SOLUTION: A thermoelectric conversion system includes an inner pipe 1 sectioning a flow passage 5 where one of heating fluid and cooling fluid flows, an outer pipe 2 arranged concentrically surrounding a periphery of the inner pipe 1 and forming a sealed space 4 with the inner pipe 1, and a thermoelectric conversion module 3 arranged in the sealed space 4 between the inner pipe 1 and the outer pipe 2 to be sandwiched between the inner pipe 1 and the outer pipe 2. A thermoelectric conversion module contact surface 1s and 2s of at least one of the inner pipe 1 and the outer pipe 2 which comes into contact with the thermoelectric conversion module has flexibility. The sealed space 4 is reduced in pressure or evacuated to make one of the heating fluid and the cooling fluid flow in the inner pipe 1 and the other of the cooling fluid and the heating fluid flow around the outer pipe 2.

Description

  The present invention relates to a thermoelectric conversion system that generates power by giving a temperature difference to a thermoelectric semiconductor. More specifically, the present invention provides a temperature difference using heat of a high-temperature fluid such as gas discharged from industrial equipment, waste water, steam, and automobile exhaust gas, or cold heat generated by an LNG vaporizer. It is related with the thermoelectric conversion system suitable for.

  A conventional thermoelectric conversion element having a general structure on a mass-production scale is an electric circuit configured by providing electrodes on the upper and lower surfaces of a plurality of pairs of thermoelectric semiconductors, and a plate having electrical insulation on the outside of each electrode, for example, a ceramic plate Alternatively, a thermoelectric conversion module is formed by assembling by bonding with a bonding material such as an adhesive or a brazing material so that a metal plate having an electric insulating film is disposed and sandwiched. For this reason, the thermoelectric conversion module is shape | molded in flat form.

  In addition, the thermoelectric conversion module may destroy the thermoelectric semiconductor that is weak in the generation of shearing force due to the thermal expansion of the heating plate that sandwiches the thermoelectric semiconductor, or may cause peeling at the joint surface between the members. In general, it is difficult to increase the size and the plane dimension is about 4 cm to 6 cm square.

  On the other hand, a conventional thermoelectric conversion system includes a thermoelectric conversion module formed into a flat plate shape, a flat plate heating duct for flowing a heating fluid that adheres closely to the thermoelectric conversion module, and a flat plate cooling duct for flowing a cooling fluid. Generally, a structure in which a thermoelectric conversion module is laminated so that the thermoelectric conversion module is sandwiched between both ducts and integrated to give a temperature difference to the thermoelectric conversion module is generally used. For this reason, in order to increase the installation density of the thermoelectric conversion modules, it is necessary to stack and use a unit in which the thermoelectric conversion modules are sandwiched between the heating duct and the cooling duct. For example, in a thermoelectric conversion system 101 that uses automobile exhaust gas as a heat source as a promising means for energy saving technology, as shown in FIGS. 23 and 24, a heating duct 109 for flowing exhaust gas and a cooling duct for flowing cooling water are used. A method of giving a temperature difference to the thermoelectric conversion module 108 is attempted by sandwiching the thermoelectric conversion module 108 between them and pressing the ducts 107 and 109 with a pressurizing mechanism such as a spring 106 and a clamp 105 (non-patent document). Reference 1). In the figure, reference numeral 102 denotes an exhaust pipe, 103 denotes a gate valve that blocks the flow of exhaust gas, and 110 denotes a manifold that connects the exhaust pipe and the heating duct. The exhaust gas is distributed by the manifold 110 on the inlet side and supplied to each heating duct 109, gathered by the manifold 110 on the outlet side, and introduced into the exhaust pipe 102.

  Here, when the exhaust gas of an automobile is used as a heating fluid, there is a problem that the temperature and flow rate of the heating fluid greatly vary depending on the traveling state. Although it cannot be generally stated, the exhaust gas is about 500 ° C. in normal traveling, it becomes 1000 ° C. or more and the exhaust gas flow rate increases at high speed traveling. In exhaust gas having a high temperature exceeding 1000 ° C., the thermoelectric conversion module may exceed the heat resistance limit and break. An increase in the exhaust gas flow rate leads to an increase in pressure loss, resulting in a loss of engine output. Therefore, in the currently developed thermoelectric conversion system for automobiles, as shown in FIG. 23, a bypass pipe 104 for flowing exhaust gas during high-speed traveling is arranged separately from the exhaust pipe 102 for introducing exhaust gas into the heating duct 109 of the thermoelectric conversion system 1. A method of arranging and monitoring the exhaust gas temperature to guide the exhaust gas to the bypass pipe 104 during high speed travel has been studied (Non-Patent Document 1).

  On the other hand, in order to protect the thermoelectric conversion module from the corrosiveness of high-temperature gas and reduce contact thermal resistance, the thermoelectric conversion module is housed in a box-shaped sealed container in a vacuum or reduced pressure state, and the thermoelectric conversion module and the heat A package-type thermoelectric conversion system has also been proposed in which a carbon sheet or silicon grease is interposed at a contact interface with a metal plate that transmits heat to reduce contact thermal resistance (Patent Documents 1 to 3).

JP 2006-49872 A WO2010-84718 A1 JP2011-238893A

Eder and J. Liebl, “Thermoelectric Waste Heat Recovery? A Technology Transfer from Aerospace to the Automotive Industry”, 1 Internationale Thermoelektrik Konferenz, Berlin, 23 Oktober, 2008.

  However, the conventional thermoelectric conversion system has a structure in which flat thermoelectric conversion modules, heating ducts and cooling ducts are stacked in layers and firmly sandwiched by leaf springs, etc., so that pressure loss, damage to thermoelectric elements, etc. Has a problem that it cannot be enlarged.

  In other words, in the structure in which the thermoelectric conversion module, the duct through which the heating fluid flows, and the duct through which the cooling fluid flow are alternately stacked and firmly sandwiched by leaf springs or the like, the pressurizing mechanism requires a sturdy structure. There is a problem that the occupied space becomes large.

  In addition, the duct for flowing the heating fluid and the duct for flowing the cooling fluid are also required to have a sturdy structure that can withstand a large applied pressure. However, having a sturdy structure for the heating duct and cooling duct has a two-way conflict with reducing heat resistance by closely contacting the thermoelectric conversion module, and it is difficult to give a large temperature difference to the thermoelectric conversion module. It is. In the conventional automobile thermoelectric conversion system 101, the module high temperature side temperature when the exhaust gas at 500 ° C. flows through the heating duct is lowered to about 200 ° C., and the heat of the exhaust gas cannot be used effectively. Currently. This is due to the low heat transfer coefficient of the exhaust gas and the contact thermal resistance present at the contact interface between the duct and the module.

  Furthermore, in order to arrange thermoelectric conversion modules at a high density, it is necessary to stack units composed of thermoelectric conversion modules sandwiched between heating ducts and cooling ducts, so that the exhaust pipe is branched into several flows. Therefore, the pressure loss increases because the structure must be introduced into a plurality of panel-shaped ducts. Moreover, with a configuration in which the exposed thermoelectric conversion module is simply sandwiched between the heating duct and the cooling duct, the thermoelectric conversion module is not only exposed to the atmosphere at high temperatures, but depending on the driving conditions of the car, there is a possibility of flooding, and oxidation There are also problems such as deterioration and electrical short circuit.

  Moreover, in the conventional thermoelectric conversion system using the exhaust gas of an automobile as a heat source, the thermoelectric conversion system (heating duct) and the bypass pipe are arranged side by side, so that the installation space is greatly restricted. This is a problem that cannot be ignored in recent automobiles where density is increasing.

  These problems are not specific to the thermoelectric conversion system provided in the exhaust pipes of automobiles, but are problems in general thermoelectric conversion systems that use the heat of fluid flowing in pipes for flowing steam and liquefied gas vaporizers, and improvements are desired. It is.

  On the other hand, since the inventions described in Patent Documents 1 and 2 are such that only one module of several centimeters is enclosed in an airtight case, it is necessary to install a large number of these for large heating / cooling ducts. However, since the ratio of the box-shaped sealed container per power generation conversion module is high, there is a problem that the thermoelectric conversion module installation density per unit area is low and the equipment cost is high. The invention described in Patent Document 3 can enclose a plurality of modules of several centimeters in a relatively large airtight case than those described in Patent Documents 1 and 2, Similar to the thermoelectric conversion system, there is a problem that the equipment cost becomes expensive.

  Therefore, there is a demand for a thermoelectric conversion system having a simple configuration in which a large number of thermoelectric conversion modules can be installed outside a large pipe or duct through which a high-temperature fluid flows.

  The present invention responds to such a demand, and an object of the present invention is to provide a thermoelectric conversion system capable of constructing a large-capacity thermoelectric conversion system with a simple structure and a large number of thermoelectric conversion modules integrated. . Another object of the present invention is to provide a thermoelectric conversion system in which a large number of thermoelectric conversion modules can be arranged in one large sealed space. Furthermore, an object of the present invention is to provide a large-capacity thermoelectric conversion system capable of increasing a power density by increasing a substantial arrangement density.

  In order to achieve such an object, the thermoelectric conversion system according to claim 1 is concentric so as to surround an inner tube that defines a flow path for flowing either the heating fluid or the cooling fluid, and the inner tube. An outer tube disposed in the inner tube to form a sealed space between the inner tube and the outer tube, and the inner tube and the outer tube in the sealed space between the inner tube and the outer tube. And a thermoelectric conversion module contact surface that comes into contact with at least one of the inner tube and the outer tube is flexible. The sealed space is decompressed or evacuated, and either the heating fluid or the cooling fluid is allowed to flow through the inner tube, and either the cooling fluid or the heating fluid is allowed to flow around the outer tube. It is.

  2. The thermoelectric conversion system according to claim 1, wherein the inner tube and the outer tube are both square tubes, are arranged concentrically, and surround the inner tube and the outer tube. It is preferable that the thermoelectric conversion module is arrange | positioned in each plane part which the pipe | tube of this opposes.

  2. The thermoelectric conversion system according to claim 1, wherein the inner tube is a circular tube and the outer tube is a square tube, and a flat surface and an inner tube that are in close contact with the thermoelectric conversion module around the inner tube. It is preferable that the thermoelectric conversion module is arranged with a metal block having a curved surface in close contact with the surface.

  The thermoelectric conversion system according to any one of claims 1 to 3, further comprising a cannula around an outer tube, and a cooling fluid or a heating fluid between the cannula and an outer tube inside the cannula. It is preferable that a flow path for flowing the other of these is formed.

  The thermoelectric conversion system according to any one of claims 1 to 4, further comprising a bypass pipe separated from a thermoelectric conversion module contact surface in contact with the thermoelectric conversion module, inside the flow path through which the heating fluid flows. The pipe normally prevents or suppresses the inflow of the heating fluid and allows the superheated fluid to pass through the flow path outside the bypass pipe. When the pipe is overheated, the entire amount or a part of the heating fluid is allowed to flow into the flow path outside the bypass pipe. It is preferable to have a flow path switching unit that prevents or suppresses the flow rate of the heated fluid that passes through.

  In the thermoelectric conversion system according to any one of claims 1 to 5, it is preferable to include a thermal expansion difference absorption region that absorbs a thermal expansion difference caused by a temperature difference between the heating fluid and the cooling fluid.

  Furthermore, in the thermoelectric conversion system according to any one of claims 1 to 6, the thermoelectric conversion module is in contact with at least one of the inner tube in contact with the thermoelectric conversion module or the thermoelectric conversion module contact surface of the outer tube. It is preferable to interpose a thermal resistance reducing substance.

  According to the thermoelectric conversion system of the first aspect, the contact pressure between the thermoelectric conversion module, the outer tube, and the inner tube is brought into close contact by the pressure applied due to the differential pressure generated in the sealed space, and the contact thermal resistance is reduced. Therefore, a temperature difference between the heating fluid and the cooling fluid is given to the thermoelectric conversion module without using a pressurizing mechanism. In addition, a thermoelectric conversion module is arranged in one continuous sealed space between the inner tube and the outer tube having a double-pipe structure so as to surround the inner tube, and can be brought into close contact with each other by the differential pressure acting on the sealed space. Therefore, it is possible to construct a large-capacity thermoelectric conversion system at a low cost by integrating many thermoelectric conversion modules. And since many thermoelectric conversion modules can be arrange | positioned in one large-sized sealed space, a substantial arrangement | positioning density can be raised and an output density (output per unit area) can be increased.

  In addition, a carbon sheet that has an effect of reducing the contact thermal resistance on the upper and lower surfaces of the thermoelectric conversion module while having a structure in which a large number of thermoelectric conversion modules are arranged around the inner tube to constitute an airtight case. The effect of reducing the contact thermal resistance with the thermoelectric conversion module by interposing a thermally conductive grease or the like is not impaired.

  In addition, since a sealed space in which a large number of thermoelectric conversion modules are installed around the inner tube can be configured simply by adopting a double tube structure, the structure is simple, space-saving, and low cost manufacturing.

  According to the invention described in claim 2, since the inner tube and the outer outer tube are configured by a square tube and arranged concentrically, the entire flat surface portion excluding the corner portion of the square tube is arranged in a thermoelectric manner. Since it can be brought into close contact with the conversion module, the structure is simple, it does not take up space, and can be manufactured at low cost.

  According to the third aspect of the present invention, since the inner tube can be a circular tube, it has sufficient pressure strength against the internal pressure and is not deformed. Therefore, a high-pressure heating fluid such as water vapor can be used, and even when such a heating fluid is used, the contact between the thermoelectric conversion module and the inner tube as the heating duct can be kept in close contact.

  According to the invention of claim 4, a simple structure in which a cannula is further arranged around the outer tube, and a flow path for flowing either the cooling fluid or the heating fluid is formed between the outer tube and the outer tube. Therefore, a temperature difference can be reliably given to a large number of thermoelectric conversion modules with respect to the tube inside the center.

  According to the invention of claim 5, a bypass pipe separated from the thermoelectric conversion module contact surface is provided inside the flow path for flowing the heating fluid, and when the heating fluid reaches a temperature exceeding the heat resistance temperature of the thermoelectric element, Since all or part of the fluid flows in, the heat given to the thermoelectric conversion module can be adjusted without changing the total amount of the heated fluid that passes through the flow path. In other words, a part of the heating fluid can flow outside the bypass pipe to heat the contact surface of the thermoelectric conversion module. For example, when configured as a thermoelectric conversion system for automobiles, the running performance is sacrificed even during high-speed running. It is also possible to ensure power generation by the thermoelectric conversion system. In addition, since the bypass pipes are arranged and aggregated in the heating duct, space can be saved as compared with the case where two ducts are arranged in parallel.

  Further, according to the invention described in claim 6, since the thermal expansion difference between the inner tube and the outer tube can be absorbed by the deformation in the thermal expansion difference absorption region, a large number of sealed spaces between the long inner tube and the outer tube are formed. A thermoelectric conversion module can be arranged to increase the size.

  Further, according to the seventh aspect of the present invention, the contact of the thermal resistance reducing substance prevents the shearing force from acting on the thermoelectric conversion module and reduces the thermal resistance of the thermoelectric conversion module. Can be given.

It is a cross-sectional view showing one embodiment of a thermoelectric conversion system according to the present invention. It is a center longitudinal cross-sectional view of one end part vicinity of the thermoelectric conversion system. It is a perspective view which shows an example of embodiment which incorporates the thermoelectric conversion system of this invention in the exhaust pipe of a motor vehicle, and generates electric power using waste gas. It is a bottom view of the same thermoelectric conversion system for vehicles. It is a center longitudinal cross-sectional view of the same thermoelectric conversion system. It is an enlarged view of the G section of FIG. It is an enlarged view of the F section of FIG. FIG. 4 is a cross-sectional view of the automotive thermoelectric conversion system, in which (A) is a cross-sectional view taken along the line AA in FIG. 4, (B) is a cross-sectional view taken along the line BB in FIG. It is sectional drawing which follows the CC line. It is a perspective view showing an example of an inner pipe used for the thermoelectric conversion system for cars. It is a perspective view which shows an example of the outer tube | pipe used for the thermoelectric conversion system for the vehicles. It is a perspective view which removes a cannula and shows the structure of the thermoelectric conversion module arrange | positioned in the outer space and inner tube which show an example of the thermoelectric conversion system for motor vehicles of FIG. 3, and the sealed space between them. 1 is a principle view showing an embodiment of a thermoelectric conversion system for an automobile exhaust pipe in which a bypass pipe is provided in a heating duct, and shows a cross-sectional structure. It is a principle figure showing the relationship between an inner pipe, a bypass pipe, and the flow-path switching means which opens and closes this bypass pipe from the front side, and shows the state which closed the bypass pipe. It is a principle figure showing the entrance vicinity of a bypass pipe from the side, and shows the state where the bypass pipe was closed. It is a principle figure showing the relationship between an inner pipe, a bypass pipe, and the flow-path switching means which opens and closes this bypass pipe from the front side, and shows the state which opened the bypass pipe. It is a principle figure showing the entrance vicinity of a bypass pipe from the side, and shows the state where the bypass pipe was opened. It is a transverse cross section showing an embodiment of a thermoelectric conversion system for exhaust pipes of a car provided with a bypass pipe. It is a longitudinal cross-sectional view of the thermoelectric conversion system. It is a principle figure showing an embodiment which applied a thermoelectric conversion system of the present invention to an open rack type LNG vaporizer (ORV). It is a cross-sectional view of a thermoelectric conversion system using an ORV heat transfer tube of an open rack type LNG vaporizer as an inner tube. It is a cross-sectional view showing an embodiment of a thermoelectric conversion system of the present invention using steam as a heat source. It is a graph which shows the experimental result which compared the temperature and the contact thermal resistance with the case where a carbon sheet is interposed between copper blocks, and the case where it does not interpose. It is a perspective view which shows the exhaust pipe incorporating the conventional thermoelectric conversion system for motor vehicles. It is a disassembled perspective view of the thermoelectric conversion system for the vehicles.

Hereinafter, the configuration of the present invention will be described in detail based on embodiments shown in the drawings.
1 and 2 show an embodiment of a thermoelectric conversion system according to the present invention. The thermoelectric conversion system includes an inner tube (hereinafter referred to as an inner tube) 1 that divides a flow path 5 through which a heating fluid or a cooling fluid flows, and an inner tube that is concentrically disposed so as to surround the inner tube 1. 1 is formed in a sealed space 4 between an inner tube 1 and an outer tube 2, and an outer tube (hereinafter referred to as an outer tube) 2 that forms a sealed space (hereinafter referred to as a sealed space) 4. The thermoelectric conversion module 3 is disposed so as to be sandwiched between the inner tube 1 and the outer tube 2. Then, the thermoelectric conversion module contact surfaces 1s, 2s that are in contact with the thermoelectric conversion module 3 of at least one of the inner tube 1 or the outer tube 2 are flexible, and the sealed space 4 is reduced in pressure or vacuum, A pressure difference between the outer space 2 and the sealed space 4 is applied to cause the thermoelectric conversion module contact surfaces 1 s and 2 s of the outer tube 2 and the inner tube 1 to be in close contact with the thermoelectric conversion module 3. Accordingly, either one of the heating fluid or the cooling fluid is allowed to flow through the inner tube 1 and the other of the cooling fluid or the heating fluid is allowed to flow around the outer tube 2 to give a temperature difference to the thermoelectric conversion module 3. it can.

  Here, if the outer tube 2 is arranged so as to surround the inner tube 1 and can form a sealed space 4 for housing the thermoelectric conversion module 3 between the outer tube 2 and the inner tube 1, the shape of the outer tube 2 is specific. It is not limited to things. The optimum shape of the outer tube 2 differs depending on the application and installation environment to which the thermoelectric conversion system is applied. However, the tube that can form the flat thermoelectric conversion module contact surfaces 1s and 2s, for example, the widest flat thermoelectric conversion module contact surface 2s. A square tube having a rectangular cross section such as a square or a rectangle is preferable. In this case, a sealed space continuous in the circumferential direction in which the thermoelectric conversion module 3 can be disposed without waste can be easily formed. In some cases, the outer tube 2 may be a triangular tube, a polygonal tube having a pentagonal shape or more, or a circular tube.

  Moreover, it is preferable that the inner tube 1 is a rectangular tube that can obtain a flat and wide thermoelectric conversion module contact surface 2 s in close contact with the thermoelectric conversion module 3 in the same manner as the outer tube 2. Therefore, the inner tube 1 and the outer tube 2 outside thereof are both constituted by square tubes, arranged concentrically, and between the opposed flat portions, that is, between the thermoelectric conversion module contact surfaces 1 s and 2 s, the thermoelectric conversion module 3. Is preferably arranged.

  On the other hand, the inner tube 1 is preferably a square tube, but is not necessarily limited to a square tube, and may be a circular tube depending on circumstances. For example, when the inner pipe 1 is a steam duct that uses steam as a heating fluid, it is most advantageous to use a seamless circular pipe to withstand the high pressure of steam. In this case, a flat surface that is in close contact with the thermoelectric conversion module 3 by interposing a metal block having high thermal conductivity and high thermal conductivity having a flat surface in close contact with the thermoelectric conversion module 3 and a curved surface in close contact with the surface of the inner tube 1. A smooth surface can be formed, and the thermoelectric conversion module 3 can be arranged. Of course, the combination of the outer tube 2 made of a circular tube and the inner tube 1 made of a square tube is not denied, and even in such a case, the surface closely contacting the thermoelectric conversion module 3 and the inner surface of the outer tube 2 are in close contact. The problem of poor adhesion between the thermoelectric conversion module 3 and the thermoelectric conversion module contact surface 2s is solved by interposing a metal block having a curved surface and high thermal conductivity and high thermal conductivity.

  Around the outer tube 2, a flow path 6 for flowing a cooling fluid or a heating fluid is formed. In this case, a cannula 7 may be further arranged around the outer tube 2, and the channel 6 may be formed between the cannula 7 and the outer tube 2 inside the cannula 7. It is good also as an open flow path like the flow of the seawater which flows down along the heat exchanger tube in an LNG vaporizer.

Further, at least one of the thermoelectric conversion module contact surfaces 1 s and 2 s of the inner tube 1 or the outer tube 2 in contact with the thermoelectric conversion module 3 and the thermoelectric conversion module 3, a carbon sheet, a heat conductive silicon grease, etc. It is preferable to intervene the contact thermal resistance reducing substance 9. The interposition of the contact thermal resistance reducing substance 9 at the contact interface is effective in reducing the contact thermal resistance, and is effective in reducing the pressurizing force necessary to give the thermoelectric conversion module as large a temperature difference as possible. For example, by an experiment in which a carbon sheet having a thermal conductivity of 5 W / mK in the thickness direction and a thickness of 0.15 mm is interposed between copper blocks and pressurized at 0.04 MPa (0.4 kg / cm ² ), carbon Compared to the contact thermal resistance of two copper blocks when no sheet is interposed, it has been found that the thermal resistance can be reduced to 1/10 or less even by adopting a conventional carbon sheet having a low thermal conductivity in the thickness direction. did. The results are shown in Table 1 and FIG.

上述の接触熱抵抗低減物質９のうちカーボンシートは、密閉空間４の真空化、減圧化あるいは不活性雰囲気化により、最も高温で使用できるＳｉＧｅ熱電半導体の使用温度１１００℃でも劣化しないため、いかなる熱電半導体にも適用可能である。

Among the contact thermal resistance reducing substances 9 described above, the carbon sheet is not deteriorated even at the use temperature of 1100 ° C. of the SiGe thermoelectric semiconductor that can be used at the highest temperature by evacuation, decompression, or inert atmosphere of the sealed space 4. It can also be applied to semiconductors.

  Further, any of the inner tube 1, the outer tube 2, and the sleeve 7 and preferably the tube that defines the flow path for flowing the cooling fluid has a temperature difference between the tube that contacts the heating fluid and the tube that contacts the cooling fluid. It is preferable to provide a thermal expansion difference absorption region 8 that absorbs the resulting thermal expansion difference. In the case of the present embodiment, the outer tube 2 defining the flow path 6 through which the cooling fluid flows is deformed in the tube axis direction (the direction of thermal expansion / contraction) on the outer tube 2 and the sleeve 7 as necessary. Alternatively, at least one or more thermal expansion difference absorption regions 8 that are displaced are provided. For example, in the outer tube 2, bellows-like thermal expansion difference absorption regions 8 are respectively formed before and after the thermoelectric conversion module 3 in the axial direction, and the thermoelectric conversion module 3 absorbs the thermal expansion difference before and after the thermoelectric conversion module 3. It prevents it from acting as a shearing force at the contacted part. In the case where the difference in thermal expansion due to the generated temperature difference is small, the thermal expansion difference absorption region 8 may be reduced in number or not installed.

The sealed space 4 is an internal pressure lower than the external pressure, for example, a reduced pressure atmosphere or a vacuum in which a differential pressure of at least 0.4 atm or more is obtained during operation. For example, after the thermoelectric conversion module 3 is accommodated in the gap between the inner tube 1 and the outer tube 2, the boundary between the inner tube and the outer tube is joined by electron beam welding or the like in a vacuum atmosphere, whereby the inner tube 1 and The outer tube 2 can be integrated and sealed at the same time, and the sealed space 4 can be reduced in pressure or vacuum. Due to the pressure applied to the sealed space 4 from the outside by this differential pressure, the thermoelectric conversion module 3, the outer tube 2 and the inner tube 1 are pressed and brought into close contact with each other, and the contact thermal resistance is reduced. Incidentally, according to experiments by the present inventors, for example, assuming a package thermoelectric conversion module 1 operating at 550 ° C. and atmospheric pressure, the enclosure pressure (P _RT ) at room temperature (27 ° C.) is −0.8 atm ( Gauge pressure), the internal pressure P ₅₅₀ when heated to 550 ° C is 0.55 atm in absolute pressure and -0.45 atm in gauge pressure, and it turns out that sufficient pressure can be given to give a sufficient temperature difference did. Since the thermoelectric conversion module 3 is well known, its detailed description and illustration are omitted. In general, the electrodes of a plurality of pairs of thermoelectric semiconductors are connected in series and sealed from the lead wires at the ends. An electric circuit is formed that conducts from a corner of the space 4 to a pair of through electrodes 12 that penetrates outside the outer tube 2.

  Here, at least one of the inner tube 1 and the outer tube 2 is flexible enough to allow the thermoelectric conversion module contact surfaces 1 s and 2 s to be in close contact with the thermoelectric conversion module 3 due to the differential pressure generated in the sealed section 4. It is preferable that it is made of a material having excellent heat transfer properties and rigidity sufficient to ensure airtightness without being broken due to a difference. For example, in this embodiment, the outer tube 2 is made of a thin metal material that is easily deformed by the above-described differential pressure. On the other hand, the inner tube 1 is preferably made of a rigid material that requires the rigidity to withstand the pressure generated by the above-described differential pressure and maintain its shape. Of course, since the heating fluid or the cooling fluid flows through the inner tube 1, the inner tube 1 has a certain degree of rigidity. Therefore, it is not necessary to have a rigid material structure, but both the outer tube 2 and the inner tube 1 can be used. There is no particular need to configure the material with flexibility. Therefore, in the case of the present embodiment, the outer tube 2 is formed of a thin plate made of a material having excellent heat conductivity, and the inner tube 1 is formed of a material having a thicker heat conductivity than the outer tube 2. In addition, in order to increase the heat transfer area, the inner pipe 1 may be provided with a large number of flanges 17 extending radially inward.

  According to the thermoelectric conversion system configured as described above, due to the pressure applied due to the differential pressure generated in the sealed space 4, the thermoelectric conversion module 3 and the outer tube 2 and the inner tube 1 are in close contact with each other, Since the contact thermal resistance is reduced, a temperature difference between the heating fluid and the cooling fluid is given to the thermoelectric conversion module 3 without using a pressurizing mechanism. Further, a differential pressure acting on the sealed space 4 by disposing the thermoelectric conversion module 3 so as to surround the inner tube 1 in one continuous sealed space 4 between the inner tube 1 and the outer tube 2 having a double-pipe structure. Therefore, it is possible to construct a large-capacity thermoelectric conversion system that saves space by integrating many thermoelectric conversion modules.

  FIG. 3 to FIG. 11 show an example of an embodiment in which the thermoelectric conversion system of the present invention is incorporated in an exhaust pipe of an automobile and power is generated using exhaust gas.

  The automobile exhaust pipe thermoelectric conversion system includes an inner pipe (hereinafter referred to as a heating duct) 1 for introducing exhaust gas, and a thin outer pipe (which is in contact with cooling fluid covering the outside of the heating duct 1). In the present embodiment, this is referred to as a cooling pipe), and a triple pipe structure of 2 and a sleeve 7 that covers the outside of the cooling pipe 2 and forms a flow path 6 through which cooling water flows between the cooling pipes 2. is there. The heating duct 1 and the cooling pipe 2 are both constituted by square tubes, and the thermoelectric conversion module 3 is inserted between the thermoelectric conversion module contact surfaces 1 s and 2 s which are in a mutually parallel relationship when arranged concentrically.

  This automobile exhaust pipe thermoelectric conversion system has an appearance as shown in FIG. 3, for example. The cooling pipe 2 is a flexible material having high thermal conductivity, for example, a thin-walled austenitic stainless seamless pipe having a thickness of about 0.1 mm to 0.2 mm, by hydroforming (hydraulic forming). This is formed into a square tube as shown in FIG. The manufacturing method of the cooling pipe 2 is not particularly limited to hydraulic forming, and a member obtained by dividing the cooling pipe 2 illustrated in FIG. 10 into two or four parts in the longitudinal direction is manufactured by press working (deep drawing process). It can also be easily manufactured by abutting them and assembling them by electron beam welding. Here, as shown in FIGS. 3 and 6 to 8, the cooling pipe 2 and the cannula 7 are provided with several thermal expansion difference absorption regions 8 that can be deformed / expanded in the direction in which thermal expansion occurs, with appropriate intervals. It is preferable to provide a structure that can absorb the difference in thermal expansion between the heating duct 1, the cooling pipe 2, and the cannula 7. As the thermal expansion difference absorption region 8, in this embodiment, a corrugated (bellows type) structural part that can easily absorb axial displacement is adopted, but in particular, the corrugated (bellows type) shown in the figure. The present invention is not limited to the shape, and can be implemented as long as it has a form or a structure that deforms in preference to other parts. In the case of using water as the cooling fluid, the cooling pipe 2 and the sleeve 7 are preferably made of an austenitic stainless material from the viewpoint of preventing rust, but are not limited thereto.

  Further, when the cooling pipe 2 is constituted by a thin square tube, the four corners may be reinforced in order to maintain the cross-sectional shape of the cooling pipe 2, particularly the flatness of the thermoelectric conversion module contact surface 2 s that contacts the thermoelectric conversion module 3. desirable. For example, as shown in FIG. 8C and FIG. 11, the rod 18 is installed in the space inside the four corners of the cooling pipe 2 in the longitudinal direction (axial direction) to maintain the corner shape of the cooling pipe 2. . The tension rod 18 is fixed to the flange 10 for fixing both ends of the cooling pipe 2 to the heating duct 1 by welding or the like. This strut rod 18 is not necessary when the cooling pipe 2 is relatively thick or small, but it is desirable to install it when the cooling pipe 2 is thin and large.

The cooling pipe 2 and the heating duct 1 define a sealed space 4 between them, and the sealed space 4 is evacuated. Therefore, the cooling pipe 2 pressurizes the thermoelectric conversion module 3 with an internal and external pressure difference (1 atm = 1 kg / cm ² = 0.1 MPa). At this time, in order to achieve good adhesion with the thermoelectric conversion module 3, it is desirable that the thickness is about 0.1 mm to 0.2 mm. The pressure in the sealed space 4 between the cooling pipe 2 and the heating duct 1 need not be limited to vacuum. Even when the pressure of the sealed space 4 is an inert gas of −0.4 kg / cm ² G (gauge pressure) = 0.6 kg / cm ² abs (absolute pressure), a contact thermal resistance reducing substance 9 such as a carbon sheet is interposed. If this is done, it corresponds to the case of a pressure difference of 0.4 atm (= 0.4 kg / cm ² = 0.04 MPa) in FIG. 22, and it has been found that there is an effect in reducing the contact thermal resistance. Accordingly, when a vacuum is applied as in this embodiment, the degree of vacuum is not important. Even if the internal pressure of the sealed space 4 is −0.9 kg / cm ² G = 0.1 kg / cm ² abs, it can be estimated from the data in FIG.

  FIG. 10 shows an example of the heating duct 1. The heating duct 1 is a solid metal square tube having a thickness of about several millimeters, preferably has coexistence with exhaust gas (heating fluid) flowing inside, and has a high thermal conductivity. For example, when flowing automobile exhaust gas (maximum temperature of about 1000 ° C.), ferritic steel is suitable. In the heating duct 1 of the present embodiment, a flange 17 is provided inside the duct to increase the heat transfer area, promote heat transfer in the duct, and easily take out the heat of the exhaust gas. It is desirable that the surface of the heating duct 1 has a high flatness and a good surface finish, and the contact thermal resistance is reduced by a good adhesion with the thermoelectric conversion module.

  As shown in FIG. 3, the sleeve 7 is a cylindrical case made of austenite / stainless steel having a thickness of about 0.1 mm to 1.0 mm, to which an inlet pipe 15 and an outlet pipe 16 for cooling water are connected. A corrugated (bellows type) thermal expansion difference absorption region 8 is provided at the center of the case, and consideration is given to absorb the thermal expansion difference between the heating duct 1 and the sleeve 7. Since the sleeve 7 is in contact with water, it is desirable to use an austenite / stainless steel material from the viewpoint of preventing rust, but the invention is not limited to this. In the present embodiment, the sleeve 7 is cylindrical, but is not limited thereto, and may be a square tube or a polygonal tube having a rectangular cross section such as a square or a rectangle. The cannula 7 and the cooling pipe 2 are welded to each other via a flange 10 fixed to the inner pipe 1 used as the heating duct 1 by welding or the like, as shown in an enlarged view in FIGS. A flow path 6 through which the cooling fluid flows is formed around the cooling pipe 2. Here, the flow path 6 around the cooling pipe 2 through which the cooling fluid flows is connected to the inlet side cooling pipe 15 and the outlet side cooling pipe 16 connected to both ends, and is in the same direction as the exhaust gas flowing in the heating duct 1. It is provided so that it may flow (cocurrent). And in the part to which the inlet side cooling piping 15 is connected, as shown to FIG. 8 (A) and FIG. 8 (B), the flat surface and thermoelectric conversion of four sides of the surface of the cooling pipe 2 which consists of a square tube It is partitioned by a cooling water distribution plate 13 having four distribution holes 14 for distributing the cooling fluid along the module contact surface 2s. Thereby, the cooling fluid introduced from the inlet side cooling pipe 15 is equally divided into four, and is made to flow evenly along each thermoelectric conversion module contact surface 2s.

It is important that the height of the gap between the heating duct 1 and the cooling pipe 2 before vacuum or decompression is set slightly higher than the total height of the thermoelectric conversion module 3 and various components to be housed. That is, when the thermoelectric conversion module 3 and various components to be stored on the heating duct 1 are installed and inserted into the cooling pipe 2, the thermoelectric conversion module 1 and the cooling pipe 2 are set to have a gap of about 1 mm. Has been. When the flange 10 is attached to both ends of the cooling pipe 2 and the heating duct 1 by electron beam welding performed in a vacuum chamber and sealed, the inside 4 of the container is evacuated at the same time as the welding is completed. When the cooling pipe 2 is deformed (dented), the thermoelectric conversion module 3 and the cooling pipe 2 are brought into close contact with each other. Therefore, the thermoelectric conversion module 3 accommodated in the sealed space 4 between the heating duct 1 and the cooling pipe 2 is 1 atmosphere (0.1 MPa = 0.1 MPa =) in a state of being in close contact with the heating duct 1 and the cooling pipe 2 under atmospheric pressure. 1 kg / cm ² ), the contact heat resistance existing between the contact surfaces can be reduced, and a large temperature difference can be given to the thermoelectric conversion module body. The gap is not limited to about 1 mm. If the cooling pipe 2 becomes large and the cooling pipe 2 becomes thin, the gap may be slightly larger. The cooling pipe 2 is integrated with the heating duct 1 by welding its both ends to the outer peripheral edge of the flange 10 fixed to the heating duct 1 by welding, and constitutes a sealed space 4. Further, two electrodes 12 that draw out the electric power of the thermoelectric conversion module 3 penetrate the flange 10. Reference numeral 11 in the figure denotes an end plate that connects and closes the ends of the cooling pipe 2 and the sleeve 7.

  According to the thermoelectric conversion system for an exhaust pipe of an automobile configured as described above, exhaust gas is caused to flow through the heating duct 1, and cooling water is supplied from the inlet side cooling pipe 15 to the flow path 6 between the sleeve 7 and the cooling pipe 2. By introducing and flowing, it is possible to generate power by giving the thermoelectric conversion module 3 a temperature difference between the exhaust gas and the cooling water.

  Next, FIG. 12 to FIG. 16 show the principle diagrams of a system in which a bypass pipe 20 is provided in the heating duct 1 as another embodiment of a thermoelectric conversion system for an exhaust pipe of an automobile. Incidentally, the present embodiment shows a schematic structure in principle, and a specific configuration is not shown.

  In the thermoelectric conversion system of this embodiment, a bypass pipe 20 for bypassing exhaust gas is built in the heating duct 1. The bypass pipe 20 is installed in a section of the heating duct 1 where at least the thermoelectric conversion module 3 is disposed, separated from the inner surface of the heating duct 1. The heating duct 1, the cooling pipe 2, the cannula 7 and the bypass pipe 20 are all formed of square tubes and have a quadruple tube structure arranged concentrically. The bypass pipe 20 includes a flow path switching means 21. When the switching condition, for example, when the temperature applied to the high temperature side of the thermoelectric conversion module 3 exceeds or approaches the heat resistance temperature of the thermoelectric element, the bypass pipe 20 is opened to discharge the exhaust gas. The bypass pipe 20 is closed at the normal time when it is bypassed and the switching condition is not satisfied. That is, the flow path switching means 21 prevents or suppresses inflow of the exhaust gas, which is a heated fluid, into the flow path 22 of the bypass pipe 20 at normal times, and causes the exhaust gas to flow in the flow path 5 outside the bypass pipe 20, thereby generating a thermoelectric conversion module. When the high temperature side of 3 falls into an overheated state, the bypass pipe 20 is opened to allow all or part of the exhaust gas to flow in, while preventing or suppressing the exhaust gas from flowing through the flow path 5 outside the bypass pipe. In the thermoelectric conversion system of the present embodiment, the heating duct 1, the cooling pipe 2, the cannula 7 and the bypass pipe 20 are all constituted by flat rectangular square tubes having a width wider than the height. However, it is not limited to this shape.

  The flow path switching means 21 of the present embodiment includes a valve rod 21a installed on the upper wall and the lower wall of the bypass pipe, and a rectangular plate-shaped valve body 21b having a proximal end attached to the valve rod 21a. A valve structure in which the valve element 21b rotates around the valve rod 21a in the heating duct 1 is formed. The valve plate 21a reaches the both side walls of the heating duct 1 when viewed from the front of the bypass pipe 20 as shown in FIGS. 13 and 15, and is opened when closed as shown in FIGS. It consists of a slightly curved rectangular plate, sometimes having a width reaching the upper and lower walls of the heating duct 1. Here, the valve plate 21a is slightly curved because, as shown in FIG. 16, the pressure loss is reduced when the flow path 5 around the bypass pipe 20 is closed and exhaust gas is introduced into the bypass pipe 20. Therefore, it is not always necessary to be curved. In the case of the present embodiment, the flow path switching means 21 is provided at the entrance of the bypass pipe 20, but is not particularly limited to this, and the same function can be achieved even if provided on the exit side of the bypass pipe 20. Do. When the valve stem 21a is arranged on the upstream side of the sealed space 4, there is no particular problem even if it passes through the heating duct 1, so it may be operated by an external actuator or a link mechanism, You may make it operate with a built-in actuator.

  A side shielding plate 23 is provided at the inlet of the bypass pipe 20. This side shielding plate 23 is a region (a portion indicated by hatching in FIGS. 12 and 15) sandwiched between the side wall portion of the bypass pipe 20 and the side wall portion of the heating duct 1 facing the bypass pipe 20 in the vicinity of the inlet of the bypass pipe 20. The flow of exhaust gas is shielded. That is, when the bypass pipe 20 is opened and the flow path 5 around the bypass pipe 1 is closed to bypass the flow path 22 of the bypass pipe 20, the exhaust gas flows between the upper and lower valve plates 21a. This is to prevent leakage. On the other hand, the side shielding plate 23 exists only in the vicinity of the inlet of the bypass pipe 20 and is not closed in areas above and below the bypass pipe. Therefore, in the state of FIGS. 13 and 14 in which the flow path switching means 21 closes the bypass pipe 20, the exhaust gas wraps behind the side shield plate 23 from the upper side and the lower side of the flow path 5, thereby side-shielding. Exhaust gas also flows in a region sandwiched between the side wall portion of the bypass pipe 20 behind the plate 23 and the side wall portion of the heating duct 1.

  For example, the switching valve 21 is opened by a controller (not shown) based on a measured value from a temperature sensor (not shown) that detects the temperature of the exhaust gas or the surface of the heating duct on the thermoelectric conversion module 3 side. The degree is to be controlled. As a result, when the exhaust gas reaches a temperature exceeding the heat resistance temperature of the thermoelectric element, the entire amount or a part of the exhaust gas is caused to flow through the flow path 22 of the bypass pipe 20 in the heating duct 1 and is passed through the heating duct 1. The thermoelectric conversion module 3 can be controlled so that excessive heat is not applied. In this case, the exhaust gas flowing into the heating duct 1 can be switched only between the inner passage 22 and the outer passage 5 without passing through the passage, so that the high-speed driving performance of the automobile is not affected. Moreover, if the flow of the exhaust gas is switched stepwise by the switching valve 21, a part of the exhaust gas can be flowed to the flow path 5 outside the bypass pipe 20 while flowing the exhaust gas to the bypass pipe 20. By applying moderate heat to the thermoelectric conversion module 3 via the heating duct 1, it is possible to maintain power generation while maintaining running performance. Of course, it is possible to flow the entire amount of exhaust gas only to the bypass pipe 20 as required. The heating duct 1 is formed with comb-like ridges 17 to increase the heat transfer area and increase the thermal conductivity. The bypass pipe 20 may be supported by a stay (not shown) or the like, but may be supported using a comb-like ridge 17. The switching condition of the flow path switching means 21 is preferably based mainly on the temperature applied to the thermoelectric conversion module 3, but is not particularly limited to this, for example, when the driving performance of an automobile is important. Alternatively, the flow rate of exhaust gas that causes deterioration in running performance due to pressure loss may be used as a reference.

  FIGS. 17 to 18 show an example in which a thermoelectric conversion system in which a bypass pipe is provided in the above-described heating duct is configured using a square square pipe. In this thermoelectric conversion system, a thermoelectric conversion module 3 is arranged on four sides around a rectangular inner tube (hereinafter referred to as a heating duct) 1 through which exhaust gas flows, and a rectangular outer tube (hereinafter referred to as an outer tube) surrounding the inner tube 1 is disposed. (Referred to as a cooling pipe) 2, one sealed space 4 for housing the four thermoelectric conversion modules 3 is formed. Reference numerals 24 and 25 in the figure denote an inlet port and an outlet port tube for connecting an exhaust pipe of an automobile formed of a circular tube and a heating duct 1 formed of a square tube of the present system.

  Here, as in the first embodiment, the cooling pipe 2 is shown in FIGS. 12 and 13 by hydroforming (thin hydraulic forming) a thin-walled austenitic stainless steel seamless pipe having a thickness of about 0.1 mm. The molded tube is used. The sleeve 7 is assembled into a square tube by electron beam welding with a half-width or quarter-width case formed by pressing a thin austenite / stainless steel sheet having a thickness of about 0.1 mm to 0.5 mm. Is adopted. Then, the rectangular tubular cooling tube 2 and the heating duct 1 are concentrically overlapped, and both ends are fixed to the heating duct 1 by electron beam welding. The rectangular tubular cannula 7 is arranged concentrically on the outside of the cooling pipe 2 and then fixed by welding or the like after interposing a sealing material for preventing water leakage at both ends. At this time, between the heating duct 1 and the cooling pipe 2 and between the cooling pipe 2 and the cannula 7, there are a sealed space 4 for housing the sealed thermoelectric conversion module 3 and a flow path 6 for flowing the cooling fluid. Composed. Between the sleeve 7 and the cooling pipe 2, a flow path 6 for flowing cooling water is formed. The sleeve 7 is provided with an inlet side cooling pipe 15 and an outlet side cooling pipe 16 and is connected to the flow path 6. A flow guide 19 that also serves as a spacer is preferably installed in the flow path 6. The flow guide 19 is provided, for example, by providing barriers alternately in the transverse direction so as to meander the cooling water introduced into the flow path 6. The flow guide 19 prevents the drift of the cooling water and a short path and prevents the thermoelectric conversion module 3. And can be cooled efficiently. The two electrodes that draw the electric power of the thermoelectric conversion module 3 penetrate the cooling pipe 2 and the cannula 7 and are drawn out of the cannula 7.

  Further, a bypass pipe 20 is provided in the heating duct 1 as shown in FIG. As shown in FIG. 18, the bypass pipe 20 is arranged inside the heating duct 1 so as to be separated from the thermoelectric conversion module contact surface 1 s of the heating duct 1 in contact with the thermoelectric conversion module 3. The entrance of the bypass pipe 20 is provided with a flow path switching means 21 and a side shielding plate 23 for switching the flow path through which the exhaust gas flows or controlling the passage amount. Based on this, it can be controlled by a controller or the like. That is, the thermoelectric conversion system guides the exhaust gas to the bypass pipe 20 when the exhaust gas exceeds the heat-resistant temperature of the thermoelectric element during high-speed traveling or the like, and closes the bypass pipe 20 with the switching valve 21 during normal traveling to heat externally. It leads to the flow path 5 of the duct 1. According to this system, even when a large fluctuation occurs in the temperature and flow rate of the exhaust gas, the flow of the exhaust gas can be changed inside the single heating duct 1, so that it is not necessary to provide a bypass pipe separately from the thermoelectric conversion system. .

  FIG. 19 to FIG. 20 show an embodiment in which the thermoelectric conversion system of the present invention using the cold generated in the LNG vaporizer is applied to an open rack LNG vaporizer (ORV). The thermoelectric conversion system 28 for LNG vaporizer is provided in the lower part of the ORV heat transfer tube 26 of the open rack type LNG vaporizer (ORV), so that it passes through the inside of the ORV heat transfer tube 26 (hereinafter abbreviated as LNG). ) To obtain the temperature difference from the seawater flowing down.

  The open rack LNG vaporizer is configured such that LNG rises inside a group of ORV heat transfer tubes installed vertically and seawater flows down along the outer surface of the ORV heat transfer tubes. Therefore, at the lower end of the ORV heat transfer tube 26, the maximum temperature difference is obtained between the seawater falling along the ORV heat transfer tube 26 and the LNG rising inside the ORV heat transfer tube 26. For example, when the seawater temperature at the upper end of the ORV heat transfer tube 26 is 20 ° C. and the LNG outlet temperature is 0 ° C., the seawater temperature at the lower end of the ORV heat transfer tube 26 is 0 ° C. and the LNG inlet temperature is −160 ° C. On the other hand, at the lower end portion of the ORV heat transfer tube 26, depending on the seawater temperature, the surface of the ORV heat transfer tube 26 may freeze due to the cold heat of LNG, thereby reducing the function. Therefore, it is preferable to install the LNG vaporizer thermoelectric conversion system 28 in the lower part of the ORV heat transfer tube where the temperature difference between the seawater temperature and the LNG temperature is large, for example, in the range of about 1 to 2 m from the lower end of the ORV heat transfer tube.

  Here, the thermoelectric conversion system 28 may use a part of the heat transfer tube 26 as the inner tube 1. In general, the ORV heat transfer tube 26 includes a large number of fins along the flow direction (axial direction) of the seawater in order to increase the heat transfer area and improve heat transfer with the seawater. Therefore, for example, as shown in FIG. 20, the outer fins at the lower part of the ORV heat transfer tube 26 are deleted to form the inner tube 1 having a rectangular outer cross-sectional shape, and a large number of thermoelectric conversion modules 3 and the outer thermoelectric conversion modules 3 are formed outside thereof. A thermoelectric conversion system 28 is configured by arranging an outer tube 2 that covers and partitions the sealed space 4 between the inner tube 1. In this case, the thermoelectric conversion system 28 can be configured without changing the overall length of the ORV heat transfer tube. The thermoelectric conversion module 3 is covered with a rectangular tube-shaped outer tube 2 by arranging the lower part of the ORV heat transfer tube 26 around each side of the inner tube 1 formed into a rectangular shape. The outer tube 2 has corrosion resistance to seawater, and from the viewpoint of moldability and weldability of deep drawing, it is preferable to use Inconel 625 (Inconel 625) and Hastelloy C4 (Hastelloy C4). The thickness of the outer tube 2 is preferably about 0.1 to 0.2 mm from the viewpoint of adhesion to the thermoelectric conversion module. The outer tube 2 is made of a thin and flexible material, and the thermoelectric conversion module 3 is connected to the inner tube 1 by depressurizing or vacuuming the sealed space 4 with the thermoelectric conversion module 3 disposed. It is possible to generate a pressing force that is pressed and closely adhered. Incidentally, in the present embodiment, the outer pipe 2 is a heating-side pipe that comes into contact with seawater that is relatively hot. In addition, as a thermoelectric conversion module which shows favorable performance in the temperature conditions in the lower part of the ORV heat transfer tube 26, for example, use of a BiTe thermoelectric conversion module is preferable.

  Further, a thermoelectric conversion system 28 configured separately from the ORV heat transfer tube 26 may be connected to the lower end of the heat transfer tube 26. In this case, as shown in FIGS. 1 and 2, for example, the thermoelectric conversion system 28 is disposed between the inner tube 1 that defines the flow path 5 through which LNG flows, and the inner tube 1 that surrounds the inner tube 1. It is comprised by the thin-walled flexible outer tube 2 which forms the sealed space 4, and the thermoelectric conversion module 3 arrange | positioned in the sealed space 4 so that it may be pinched | interposed between the inner tube 1 and the outer tube 2. . And the thermoelectric conversion system 28 can be comprised as a lower part of the ORV heat transfer pipe 26 by connecting the inner pipe 1 to the lower end of the ORV heat transfer pipe 26 by welding or the like. Here, since the aluminum tube is generally used as the material of the ORV heat transfer tube 26, the material of the inner tube 1 is preferably an aluminum alloy.

  In addition, the shape of the surface becomes discontinuous at the connecting portion between the ORV heat transfer tube 26 and the outer tube 2 of the thermoelectric conversion system 28. For this reason, there is a possibility that seawater flowing down the surface of the heat transfer tube from the upper end of the ORV heat transfer tube 26 peels off at the discontinuous portion and cannot be completely attached to the surface of the outer tube 2. Therefore, a transition region 27 of about several tens of centimeters in which the cross-sectional shape gradually changes from the contour shape of the ORV heat transfer tube 26 to the contour shape of the thermoelectric conversion system 28, that is, the contour shape of the outer tube 2 is provided at the connection portion between them. It is preferable that the seawater stream 6 flowing down along the surface of the heat pipe 26 is not separated from the surface of the outer pipe 2. Further, the outer pipe 2 has a thermal expansion difference absorption region 8 for absorbing a thermal expansion difference generated in the axial direction between the inner pipe and the inner pipe due to a temperature difference during operation and stop, for example, as shown in FIG. It is desirable to provide at least one pan-rose thermal expansion difference absorption region 8.

FIG. 21 shows an example in which steam (water vapor) is used as a heat source as another embodiment of the thermoelectric conversion system of the present invention.
When steam is used as a heat source, the inner pipe (heating duct) 1 is preferably a seamless (seamless) circular pipe. This is because a circular tube is most advantageous to withstand the high pressure of steam. For example, the saturated vapor pressure of steam at 200 ° C. is about 16 bar. Therefore, an austenitic stainless steel (for example, SUS304 or the like) circular tube having a diameter of 100 mm and a thickness of 1 mm has a sufficient pressure resistance against an internal pressure of 16 bar. Moreover, the point that the circular tube is never deformed unless it bursts is decisively advantageous as the heating duct 1 that contacts the thermoelectric conversion module 3. In the case of a rectangular heating duct, the duct is deformed (swelled) by the internal pressure, and the adhesion of the thermoelectric conversion module may be hindered, which is not suitable for flowing a relatively high-pressure heating fluid or cooling fluid.

  Since a circular pipe is adopted as the inner pipe 1 that is the center of the thermoelectric conversion system, a thermoelectric conversion module is provided around the inner pipe 1 by interposing a metal block 29 having excellent thermal conductivity and thermal conductivity such as copper and aluminum. Therefore, it is necessary to form a flat surface to be in close contact with 3. The block 29 is a saddle type having a flat surface in close contact with the thermoelectric conversion module 3 and a curved surface in close contact with the surface of the inner tube 1. In order for this block 29 to maintain adhesiveness with the inner tube 1 and the thermoelectric conversion module 3 and to reduce contact thermal resistance, it is desirable that the contact surface with the both has a good surface finish. Further, although not shown, it is desirable that a carbon sheet having a thickness of about 0.15 mm is interposed on the contact surface as a contact heat resistance substance. In the present embodiment, the four saddle-shaped blocks 29 are installed around the inner tube 1. However, the present invention is not limited to this, and the outer tube 2 is a flat tube such as a rectangle. There may be two or more than four depending on the cross-sectional shape of the tubular outer tube 2. In this sectional view, one (that is, one row) of thermoelectric conversion modules 3 is placed in each vertical block 29, but a plurality of (a plurality of rows) of thermoelectric conversion modules 3 may be arranged.

  Here, the thermoelectric conversion system of the present embodiment employs a circular pipe as the inner pipe 1, except that the saddle type block 29 is interposed between the inner pipe 1 and the thermoelectric conversion module 3. The basic configuration is the same as that of the embodiment shown in FIG. That is, the thermoelectric conversion system has a structure in which the thermoelectric conversion module 3 is brought into close contact with the bowl-shaped block 29 and the outer tube 2 made of a thin square tube is brought into close contact with the outside of the thermoelectric conversion module 3. Further, a tension bar 18 is provided inside the four corners of the outer tube 2 so that the shape of the outer tube 2 is maintained. The tension rod 18 is fixed by the flange portions 10 at both ends. The tension rod 18 is not essential, but it is desirable to provide it when the outer tube 2 is thin and large. On the other hand, the tension rod 18 is not necessary when the outer tube 2 is relatively thick or small. A cannula 7 made of a square tube is provided outside the outer tube 2, and a flow path 6 through which a cooling fluid flows is formed in a gap between the outer tube 2 and the cannula 7. The flow path 6 is provided with a flow path guide 19 that also serves as a spacer for guiding the cooling fluid to meander. The flow path guide 19 is preferably installed to prevent uneven flow of the cooling fluid or a short path and to uniformly apply heat to the thermoelectric conversion module 3, but it is not always necessary to provide the flow path guide 19.

  In the present embodiment, since all of the inner tube 1, the outer tube 2 and the sleeve 7 are in contact with water, it is desirable to use austenitic stainless steel such as SUS304 from the viewpoint of preventing rust. The saddle-shaped block 29 is suitably made of copper as a material having high thermal conductivity, but aluminum may be used when weight reduction is important. Further, the inner pipe 1 is optimally a seamless circular pipe, but a pipe with a seam can be used if the roundness is good.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the flexible outer tube 2 is arranged outside the rigid inner tube 1, but the present invention is not limited to this. The flexible inner tube 1 may be arranged inside the rigid outer tube 2. The inner tube 1 and the outer tube 2 can be implemented as long as both can be thin and flexible as long as the shape can be maintained by support with other components, heating fluid, or cooling fluid.

DESCRIPTION OF SYMBOLS 1 Inner pipe 1s Thermoelectric conversion module contact surface of inner pipe 2 Outer pipe 2s Thermoelectric conversion module contact surface of outer pipe 3 Thermoelectric conversion module 4 Sealed space 5 Flow path through which either heating fluid or cooling fluid flows in inner pipe 6 Flow path for flowing either cooling fluid or heating fluid outside the outer pipe 7 Cannula 8 Thermal expansion difference absorption region 9 Contact thermal resistance reducing substance 20 Bypass pipe 21 Flow path switching means for opening and closing the bypass pipe 29 Thermoelectric conversion A metal block with a flat surface in close contact with the module and a curved surface in close contact with the inner tube surface

Claims (7)

An inner tube that defines a flow path for flowing either the heating fluid or the cooling fluid;
An outer tube disposed concentrically to surround the inner tube and forming a sealed space with the inner tube;
A thermoelectric conversion module arranged to be sandwiched between the inner tube and the outer tube in the sealed space between the inner tube and the outer tube; and The thermoelectric conversion module contact surface that contacts the thermoelectric conversion module of at least one of the outer tube or the outer tube has flexibility,
The sealed space is depressurized or vacuumed,
One of the heating fluid and the cooling fluid is allowed to flow through the inner tube, and the other of the cooling fluid and the heating fluid is allowed to flow around the outer tube. The inner tube and the outer tube outside thereof are both square tubes and are arranged concentrically,
2. The thermoelectric conversion system according to claim 1, wherein the thermoelectric conversion module is arranged on each of the opposing planar portions of the inner tube and the outer tube so as to surround the inner tube. The inner tube is a circular tube and the outer tube is a square tube;
The thermoelectric conversion module is disposed around the inner tube with a metal block having a flat surface in close contact with the thermoelectric conversion module and a curved surface in close contact with the surface of the inner tube. The thermoelectric conversion system according to claim 1.   A cannula is further disposed around the outer tube, and a flow path is formed between the cannula and the outer tube on the inner side for flowing either the cooling fluid or the heating fluid. Item 4. The thermoelectric conversion system according to any one of Items 1 to 3. In the inside of the flow path through which the heating fluid flows, a bypass pipe separated from the thermoelectric conversion module contact surface in contact with the thermoelectric conversion module is provided.
The bypass pipe normally prevents or suppresses the inflow of the heating fluid and allows the superheated fluid to pass through the flow path outside the bypass pipe. When the overheat is overheated, the entire amount or a part of the heating fluid is caused to flow into the bypass pipe. The thermoelectric conversion system according to any one of claims 1 to 4, further comprising a flow path switching unit that blocks or suppresses a flow rate of the heating fluid that passes through the flow path outside the pipe.   The thermoelectric conversion system according to any one of claims 1 to 5, further comprising a thermal expansion difference absorption region that absorbs a thermal expansion difference caused by a temperature difference between the heating fluid and the cooling fluid.   2. The contact thermal resistance reducing substance is interposed in at least one of the thermoelectric conversion module and the inner pipe contacting the thermoelectric conversion module or the thermoelectric conversion module contact surface of the outer pipe. The thermoelectric conversion system as described in any one of 1-6.

Images