Thermoelectric generator unit and method of testing the thermoelectric generator unit

A thermoelectric generator unit according to this disclosure includes a plurality of tubular thermoelectric generators, each of which generates electromotive force based on a difference in temperature between the inner and outer peripheral surfaces. The unit further includes a plurality of electrically conductive members providing electrical connection for the generators and a container housing the generators inside. The container includes a shell surrounding the generators and a pair of plates, at least one of which has a plurality of openings and channels. Each channel houses an electrically conductive member. The generators are electrically connected together in series via the electrically conductive member. At least one of the channels has an interconnection which connects at least two of the openings together and a testing hole portion. The testing hole portion runs from the interconnection through an outer edge of the at least one plate.

BACKGROUND

1. Technical Field

The present disclosure relates to a thermoelectric generator unit including a thermoelectric conversion element which converts heat into electric power, and also relates to a method of testing the thermoelectric generator unit.

2. Description of the Related Art

A thermoelectric conversion element is an element which can convert either heat into electric power or electric power into heat. A thermoelectric conversion element made of a thermoelectric material that exhibits the Seebeck effect can obtain thermal energy from a heat source at a relatively low temperature (of 200 degrees Celsius or less, for example) and can convert the thermal energy into electric power. With a thermoelectric generation technique based on such a thermoelectric conversion element, it is possible to collect and effectively utilize thermal energy which would conventionally have been dumped unused into the ambient in the form of steam, hot water, exhaust gas, or the like.

A thermoelectric conversion element made of a thermoelectric material will be hereinafter referred to as a “thermoelectric generator”. A thermoelectric generator generally has a so-called “π structure” where p- and n-type semiconductors, of which the carriers have mutually different electrical polarities, are combined together (see Japanese Laid-Open Patent Publication No. 2013-016685, for example). In a thermoelectric generator with the π structure, a p-type semiconductor and an n-type semiconductor are connected together electrically in series together and thermally parallel with each other. In the π structure, the direction of a temperature gradient and the direction of electric current flow are either mutually parallel or mutually antiparallel to each other. This makes it necessary to provide an output terminal on the high-temperature heat source side or the low-temperature heat source side. Consequently, to connect a plurality of such thermoelectric generators, each having the π structure, electrically in series together, a complicated wiring structure is required.

PCT International Application Publication No. 2008/056466 (which will be hereinafter referred to as “Patent Document 1”) discloses a thermoelectric generator including a stacked body of a bismuth layer and a layer of a different metal from bismuth between first and second electrodes that face each other. In the thermoelectric generator disclosed in Patent Document 1, the planes of stacking are inclined with respect to a line that connects the first and second electrodes together. PCT International Application Publication No. 2012/014366 (which will be hereinafter referred to as “Patent Document 2”), kanno et al., preprints from the 72ndSymposium of the Japan Society of Applied Physics, 30a-F-14 “A Tubular Electric Power Generator Using Off-Diagonal Thermoelectric Effects” (2011), and A. Sakai et al., International conference on thermoelectrics 2012 “Enhancement in performance of the tubular thermoelectric generator (TTEG)” (2012) disclose tubular thermoelectric generators.

SUMMARY

Development of a practical thermoelectric generator unit that uses such thermoelectric generation technologies and a method of testing such a unit is awaited.

A thermoelectric generator unit according to the present disclosure includes a plurality of tubular thermoelectric generators. Each of the plurality of tubular thermoelectric generators has an outer peripheral surface, an inner peripheral surface and a flow path defined by the inner peripheral surface, and generates electromotive force in an axial direction of each said tubular thermoelectric generator based on a difference in temperature between the inner and outer peripheral surfaces. The thermoelectric generator unit further includes: a plurality of electrically conductive members providing electrical connection for the plurality of tubular thermoelectric generators, and a container housing the plurality of tubular thermoelectric generators inside. The container includes: fluid inlet and outlet ports through which a fluid flows inside the container, a plurality of openings into which the respective tubular thermoelectric generators are inserted, a shell surrounding the plurality of tubular thermoelectric generators, and a pair of plates. Each of the pair of plates is fixed to the shell and at least one of which has the plurality of openings and channels. Each channel houses an electrically conductive member. Respective ends of the tubular thermoelectric generators are inserted into the plurality of openings of the plates. At least one of the channels has an interconnection which connects at least two of the plurality of openings together and a testing hole portion which runs from the interconnection through an outer edge of the at least one plate. The plurality of tubular thermoelectric generators are electrically connected together in series via the electrically conductive member that is housed in the interconnection of the at least one channel.

A thermoelectric generator unit and method of testing the thermoelectric generator unit according to the present disclosure contributes to increasing the practicality of thermoelectric power generation.

These general and specific aspects may be implemented using a system and a method, and any combination of systems and methods.

DETAILED DESCRIPTION

A thermoelectric generator unit according to a non-limiting exemplary implementation of the present disclosure includes a plurality of tubular thermoelectric generators. Each of the tubular thermoelectric generators has an outer peripheral surface, an inner peripheral surface and a flow path defined by the inner peripheral surface. Each tubular thermoelectric generator is configured to generate electromotive force in its axial direction based on a difference in temperature between the inner and outer peripheral surfaces.

This thermoelectric generator unit further includes a container housing the plurality of tubular thermoelectric generators inside and a plurality of electrically conductive members providing electrical connection for the plurality of tubular thermoelectric generators. The container has fluid inlet and outlet ports through which a fluid flows inside the container, and a plurality of openings into which the respective tubular thermoelectric generators are inserted. The container also includes a shell surrounding the tubular thermoelectric generators and a pair of plates, each of the pair of plates is fixed to the shell. Each of the pair of plates has a plurality of openings and channels. Each channel houses an electrically conductive member.

Respective ends of the tubular thermoelectric generators are inserted into the plurality of openings of the plates. At least one of the channels has an interconnection which connects at least two of the plurality of openings together and a testing hole portion which runs from the interconnection through an outer edge of the at least one plate. And the plurality of tubular thermoelectric generators are electrically connected together in series via the electrically conductive member that is housed in the interconnection of the at least one channel.

As will be described in detail later, a thermoelectric generator unit according to an embodiment includes a plurality of tubular thermoelectric generators. Each of the tubular thermoelectric generators generates electromotive force based on a temperature difference created between the inner and outer peripheral surfaces of each of those generators, thereby taking electric power out of the thermoelectric generator unit. By connecting those tubular thermoelectric generators electrically in series together, the electromotive forces generated in those tubular thermoelectric generators can be superposed one upon the other, and even greater electric power can be extracted.

In this case, while the thermoelectric generator unit is operating, some failure could occur under harsh conditions in any of those tubular thermoelectric generators. For example, if the difference in temperature between the inner and outer peripheral surfaces of any tubular thermoelectric generator changes steeply or if the thermoelectric generator unit is operated for a long time continuously, the tubular thermoelectric generator would be subjected to mechanical or thermal stress and could get damaged. In such a situation, it would be beneficial if the failure could be located without breaking up the thermoelectric generator unit. According to an embodiment of the present disclosure, the failure can be located by a simple method without breaking up the thermoelectric generator unit, thus contributing to increasing practicality of thermoelectric power generation.

<Basic Configuration and Principle of Operation of Thermoelectric Generator>

Before embodiments of a thermoelectric generator unit according to the present disclosure are described, the basic configuration and principle of operation of a thermoelectric generator for use in the thermoelectric generator unit will be described. As will be described later, in a thermoelectric generator unit according to the present disclosure, a tubular thermoelectric generator is used. However, the principle of operation of such a tubular thermoelectric generator can also be understood more easily through description of the principle of operation of a thermoelectric generator in a simpler shape.

First of all, look atFIGS. 1A and 1B.FIG. 1Ais a schematic cross-sectional view of a thermoelectric generator10with a generally rectangular parallelepiped shape, andFIG. 1Bis a top view of the thermoelectric generator10. For reference sake, X-, Y- and Z-axis that intersect with each other at right angles are shown inFIGS. 1A and 1B. The thermoelectric generator10shown inFIGS. 1A and 1Bincludes a stacked body with a structure in which multiple metal layers and thermoelectric material layers22are alternately stacked one upon the other so that their planes of stacking are inclined. Although the stacked body is supposed to have a rectangular parallelepiped shape in this example, the principle of operation will be the same even if the stacked body has any other shape.

In the thermoelectric generator10shown inFIGS. 1A and 1B, first and second electrodes E1and E2are arranged so as to sandwich the stacked body horizontally between them. In the cross section shown inFIG. 1A, the planes of stacking define an angle of inclination θ (where 0<θ<π radians) with respect to the Z-axis direction. The angle of inclination θ will be hereinafter simply referred to as an “inclination angle”.

In the thermoelectric generator10with such a configuration, when a temperature difference is created between its upper surface10aand its lower surface10b, the heat will be transferred preferentially through the metal layers20with higher thermal conductivity than the thermoelectric material layers22. Thus, a Z-axis direction component is produced in the temperature gradient of each of those thermoelectric material layers22. As a result, electromotive force occurs in the Z-axis direction in each thermoelectric material layer22due to the Seebeck effect, and eventually the electromotive forces are superposed one upon the other in series inside this stacked body. Consequently, a significant potential difference is created as a whole between the first and second electrodes E1and E2. A thermoelectric generator including the stacked body shown inFIGS. 1A and 1Bis disclosed in PCT International Application Publication No. 2008/056466 (Patent Document 1), the entire disclosure of which is hereby incorporated by reference.

FIG. 2schematically illustrates a situation where a high-temperature heat source120is brought into contact with the upper surface10aof the thermoelectric generator10and a low-temperature heat source140is brought into contact with its lower surface10b. In such a situation, heat Q flows from the high-temperature heat source120toward the low-temperature heat source140through the thermoelectric generator10, and electric power P can be extracted from the thermoelectric generator10through the first and second electrodes E1and E2. From a macroscopic point of view, in this thermoelectric generator10, the direction of temperature gradient (Y-axis direction) and the direction of the electric current (Z-axis direction) intersect with each other at right angles. That is why there is no need to create a temperature difference between the two electrodes E1and E2, through which the electric power is extracted.FIG. 2schematically illustrates an example in which the electric power P flows from the left toward the right on the paper. However, this is only an example. For example, if the kind of the thermoelectric material used is changed, the electric power P may flow in the opposite direction from the one shown in FIG.2.

Although the stacked body of the thermoelectric generator10is supposed to have a rectangular parallelepiped shape in the example described above for the sake of simplicity, a thermoelectric generator, of which the stacked body has a tubular shape, will be used in the embodiments to be described below. A thermoelectric generator in such a tubular shape will be hereinafter referred to as a “tubular thermoelectric generator” or “thermoelectric generation tube”. It should be noted that in the present specification, the term “tube” is interchangeably used with the term “pipe”, and is to be interpreted to encompass both a “tube” and a “pipe”.

Next, a thermoelectric generator unit according to the present disclosure will be outlined.

First of all, look atFIGS. 3A and 3B.FIG. 3Ais a perspective view illustrating an exemplary tubular thermoelectric generator T. The tubular thermoelectric generator T includes a tube body Tb in which multiple metal layers20and thermoelectric material layers22with a through hole at their center are alternately stacked one upon the other so as to be inclined and a pair of electrodes E1and E2. A method of making such a tubular thermoelectric generator T is disclosed in Patent Document 2, for example. According to the method disclosed in Patent Document 2, multiple metallic cups, each having a hole at the bottom, and multiple thermoelectric material cups, each also having a hole at the bottom, are alternately stacked one upon the other and subjected to a plasma sintering process in such a state, thereby binding them together. The entire disclosure of PCT International Application Publication No. 2012/014366 is hereby incorporated by reference.

The tubular thermoelectric generator T shown inFIG. 3Amay be connected to a conduit so that a hot heat transfer medium (such as hot water) flows through a flow path defined by its inner peripheral surface (which will sometimes be referred to as an “internal flow path” hereinbelow). In that case, the outer peripheral surface of the tubular thermoelectric generator T may be brought into contact with a cold heat transfer medium (such as cold water). In this manner, a temperature difference is created between the inner and outer peripheral surfaces of the tubular thermoelectric generator T, thereby generating a potential difference between the pair of electrodes E1and E2. As a result, the electric power generated can be extracted. Hereinbelow, the hot heat transfer medium and the cold heat transfer medium will sometimes be simply referred to as “the hot medium” and “the cold medium”, respectively.

It should be noted that although these heat transfer media will be referred to herein as “hot” and “cold” heat transfer media, these terms “hot” and “cold” actually do not refer to specific absolute temperature levels of those media but just mean that there is a relative temperature difference between those media. Also, the “medium” is typically a gas, a liquid or a fluid that is a mixture of a gas and a liquid. However, the “medium” may contain solid, e.g., powder, which is dispersed within a fluid.

The shape of the tubular thermoelectric generator T may be anything tubular, without being limited to cylindrical. In other words, when the tubular thermoelectric generator T is cut along a plane which is perpendicular to the axis of the tubular thermoelectric generator T, the resultant shapes created by sections of the “outer peripheral surface” and the “inner peripheral surface” do not need to be circles, but may be any closed curves, e.g., ellipses or polygons. Although the axis of the tubular thermoelectric generator T is typically linear, it is not limited to being linear. These can be seen easily from the principle of thermoelectric generation that has already been described with reference toFIGS. 1A, 1B and 2.

FIG. 3Bis a perspective view illustrating a general configuration for an exemplary thermoelectric generator unit100according to the present disclosure. The thermoelectric generator unit100shown inFIG. 3Bincludes a plurality of tubular thermoelectric generators T, a container30which houses these tubular thermoelectric generators T inside, and a plurality of electrically conductive members J to electrically connect these tubular thermoelectric generators T together. In the example illustrated inFIG. 3B, ten tubular thermoelectric generators T1to T10are housed inside the container30. Those ten tubular thermoelectric generators T1to T10are typically arranged substantially parallel to each other but may also be arranged in any other pattern.

Each of these tubular thermoelectric generators T1to T10has an outer peripheral surface, an inner peripheral surface and an internal flow path defined by the inner peripheral surface as described above. Each of these tubular thermoelectric generators T1to T10is configured to generate electromotive force along its axis based on a difference in temperature created between the inner and outer peripheral surfaces. That is to say, by creating a temperature difference between the outer and inner peripheral surfaces in each of those tubular thermoelectric generators T1to T10, electric power generated can be extracted from the tubular thermoelectric generators T1to T10. For example, by bringing a hot medium and a cold medium into contact with the internal flow path and the outer peripheral surface, respectively, in each of the tubular thermoelectric generators T1to T10, electric power generated can be extracted from the tubular thermoelectric generators T1to T10. Conversely, a cold medium and a hot medium may be brought into contact with the inner and outer peripheral surfaces, respectively, in each of the tubular thermoelectric generators T1to T10.

In the example illustrated inFIG. 3B, the medium to be brought into contact with the outer peripheral surfaces of the tubular thermoelectric generators T1to T10inside the container30and the medium to be brought into contact with the inner peripheral surface of each tubular thermoelectric generator T1to T10in the internal flow path of the respective tubular thermoelectric generator are supplied through different conduits (not shown), thus being isolated so as not to intermix.

FIG. 4is a block diagram illustrating an exemplary configuration for introducing a temperature difference between the outer and inner peripheral surfaces of the tubular thermoelectric generator T. InFIG. 4, the dotted arrow H schematically indicates the flow of a hot medium and the solid arrow L schematically indicates the flow of a cold medium. In the example illustrated inFIG. 4, the hot and cold media are circulated by pumps P1and P2, respectively. For example, the hot medium may be supplied to the internal flow path in each of the tubular thermoelectric generators T1to T10and the cold medium may be supplied into the container30. Although not shown inFIG. 4, heat is supplied from a high-temperature heat source (such as a heat exchanger, not shown) to the hot medium and heat is supplied from the cold medium to a low-temperature heat source (not shown, either). As the high-temperature heat source, steam, hot water and exhaust gas at relatively low temperatures (of 200 degrees Celsius or less, for example) which have been dumped unused into the ambient can be used. Naturally, heat sources at even higher temperatures may also be used.

In the example illustrated inFIG. 4, the hot and cold media are supposed to be circulated by the pumps P1and P2, respectively. However, this is only an example of a thermoelectric generator unit according to the present disclosure. Alternatively, one or both of the hot and cold media may be dumped from their heat source into the ambient without forming a circulating system. For example, high-temperature hot spring water that has sprung from the ground may be supplied as the hot medium to the thermoelectric generator unit100, and when its temperature lowers, the hot spring water may be used for any purpose other than power generation or just discharged. The same can be said about the cold medium. That is to say, phreatic water, river water or seawater may be pumped up and supplied to the thermoelectric generator unit100. After any of these kinds of water has been used as the cold medium, its temperature may be lowered to an appropriate level as needed and then the water may be either poured back to its original source or just discharged to the ambient.

Now look atFIG. 3Bagain. In the thermoelectric generator unit100according to the present disclosure, a plurality of tubular thermoelectric generators T are electrically connected together via the electrically conductive members J. In the example illustrated inFIG. 3B, each pair of tubular thermoelectric generators T arranged adjacent to each other are connected together via their associated electrically conductive member J. As a result, these tubular thermoelectric generators T are electrically connected together in series as a whole. For example, the respective right ends of two tubular thermoelectric generators T3and T4which are illustrated as front ones inFIG. 3Bare connected together with an electrically conductive member J3. On the other hand, the respective left ends of these two tubular thermoelectric generators T3and T4are connected to two other tubular thermoelectric generators T2and T5via electrically conductive members J2and J4, respectively.

FIG. 5schematically illustrates how those tubular thermoelectric generators T1to T10may be electrically connected together. As shown inFIG. 5, each of the electrically conductive members J1to J9electrically connects its associated two tubular thermoelectric generators together. That is to say, the electrically conductive members J1to J9are arranged to electrically connect these tubular thermoelectric generators T1to T10in series together as a whole. In this example, the circuit comprised of the tubular thermoelectric generators T1to T10and the electrically conductive members J1to J9is a traversable one. However, this circuit may also include some tubular thermoelectric generators which are connected in parallel, and it is not essential that the circuit be traversable.

In the example illustrated inFIG. 5, an electric current may flow from the tubular thermoelectric generator T1to the tubular thermoelectric generator T10, for example. However, the electric current may also flow from the tubular thermoelectric generator T10to the tubular thermoelectric generator T1. The direction of this electric current is determined by the kind of a thermoelectric material used to make the tubular thermoelectric generator T, the direction of flow of heat generated between the inner and outer peripheral surfaces of the tubular thermoelectric generator T, and the direction of inclination of the planes of stacking in the tubular thermoelectric generator T, for example. The connection of the tubular thermoelectric generators T1to T10is determined so that electromotive forces occurring in the respective tubular thermoelectric generators T1to T10do not cancel one another, but are superposed.

It should be noted that the direction in which the electric current flows through the tubular thermoelectric generators T1to T10has nothing to do with the direction in which the medium (i.e., either the hot medium or the cold medium) flows through the internal flow path of the tubular thermoelectric generators T1to T10. For instance, in the example illustrated inFIG. 5, the medium going through the internal flow path may flow from the left toward the right on the paper in each and every one of the tubular thermoelectric generators T1to T10.

<Detailed Configuration of Tubular Thermoelectric Generator T>

Next, a detailed configuration for the tubular thermoelectric generator T will be described with reference toFIGS. 6A and 6B.FIG. 6Ais a perspective view illustrating one of the tubular thermoelectric generators T (e.g., the tubular thermoelectric generator T1in this example) that the thermoelectric generator unit100has. The tubular thermoelectric generator T1includes a tube body Tb1and first and second electrodes E1and E2which are arranged at both ends of the tube body Tb1. The tube body Tb1has a configuration in which multiple metal layers20and multiple thermoelectric material layers22are alternately stacked one upon the other. In the present specification, the direction in which a line that connects the first and second electrodes E1and E2together runs will sometimes be referred to as a “stacking direction” hereinbelow. The stacking direction agrees with the axial direction of the tubular thermoelectric generator.

FIG. 6Bschematically illustrates a cross section of the tubular thermoelectric generator T1as viewed on a plane including the axis (center axis) of the tubular thermoelectric generator T1. As shown inFIG. 6B, the tubular thermoelectric generator T1has an outer peripheral surface24and an inner peripheral surface26. A region which is defined by the inner peripheral surface26forms a flow path F1. In the illustrated example, cross sections of the outer peripheral surface24and the inner peripheral surface26taken perpendicular to the axial direction each present the shape of a circle. However, these shapes are not limited to circles, but may be ellipses or polygons, as described above. The cross-sectional area of the flow path on such a cross section that intersects with the axial direction at right angles is not particularly limited. The cross-sectional area of the flow path or the number of tubular thermoelectric generators to provide may be determined appropriately by the flow rate of the medium to be supplied into the internal flow path of the tubular thermoelectric generator T.

Although the first and second electrodes E1and E2each have a circular cylindrical shape in the example illustrated inFIGS. 6A and 6B, this is only an example and the first and second electrodes E1and E2do not have to have such a shape. At or near the respective end of the tube body Tb1, the first electrode E1and the second electrode E2may each have any arbitrary shape which is electrically connectable to at least one of the metal layers20or the thermoelectric material layers22and which does not obstruct the flow path F1. In the example shown inFIGS. 6A and 6B, the first electrode E1and the second electrode E2have outer peripheral surfaces conforming to the outer peripheral surface24of the tube body Tb1; however, it is not necessary for the outer peripheral surfaces of the first electrode E1and the second electrode E2to conform to the outer peripheral surface24of the tube body Tb1. For example, the diameter of the outer peripheral surface (i.e., the outer diameter) of the first and second electrodes E1and E2may be larger or smaller than that of the tube body Tb1. Also, when viewed on a plane that intersects with the axial direction at right angles, the cross-sectional shape of the first and second electrodes E1and E2may be different from that of the outer peripheral surface24of the tube body Tb1.

The first and second electrodes E1and E2may be made of a material with electrical conductivity and are typically made of a metal. The first and second electrodes E1and E2may be comprised of a single or multiple metal layers20which are located at or near the ends of the tube body Tb1. In that case, portions of the tube body Tb1function as the first and second electrodes E1and E2. Alternatively, the first and second electrodes E1and E2may also be formed out of a metal layer or annular metallic member which is arranged so as to partially cover the outer peripheral surface of the tube body Tb1. Still alternatively, the first and second electrodes E1and E2may also be a pair of circular cylindrical metallic members which are fitted into the flow path F1through the ends of the tube body Tb1so as to be in contact with the inner peripheral surface of the tube body Tb1.

As shown inFIG. 6B, the metal layers20and thermoelectric material layers22are alternately stacked one upon the other so as to be inclined. A tubular thermoelectric generator with such a configuration operates on basically the same principle as what has already been described with reference toFIGS. 1A, 1B and 2. That is why if a temperature difference is created between the outer peripheral surface24and inner peripheral surface26of the tubular thermoelectric generator T1, a potential difference is generated between the first and second electrodes E1and E2. The general direction of the temperature gradient is the radial direction of the tubular thermoelectric generator T1(i.e., the direction that intersects with the stacking direction at right angles).

The inclination angle θ of the planes of stacking in the tube body Tb1may be set within the range of not less than 5 degrees and not more than 60 degrees, for example. The inclination angle θ may be not less than 20 degrees and not more than 45 degrees. An appropriate range of the inclination angle θ varies according to the combination of the material to make the metal layers20and the thermoelectric material to make the thermoelectric material layers22.

The ratio of the thickness of each metal layer20to that of each thermoelectric material layer22in the tube body Tb1(which will be hereinafter simply referred to as a “stacking ratio”) may be set within the range of 20:1 to 1:9, for example. In this case, the thickness of the metal layer20refers herein to its thickness as measured perpendicularly to the plane of stacking (i.e., the thickness indicated by the arrow Th inFIG. 6B). In the same way, the thickness of the thermoelectric material layer22refers herein to its thickness as measured perpendicularly to the plane of stacking. It should be noted that the total number of the metal layers20and thermoelectric material layers22that are stacked one upon the other may be set appropriately.

The metal layers20may be made of any arbitrary metallic material. For example, the metal layers20may be made of nickel or cobalt. Nickel and cobalt are examples of metallic materials which exhibit excellent thermoelectric generation properties. Optionally, the metal layers20may include silver or gold. Furthermore, the metal layers20may include any of these metallic materials either by itself or as their alloy. If the metal layers20are made of an alloy, the alloy may include copper, chromium or aluminum. Examples of such alloys include constantan, CHROMEL™, and ALUMEL™.

The thermoelectric material layers22may be made of any arbitrary thermoelectric material depending on their operating temperature. Examples of thermoelectric materials which may be used to make the thermoelectric material layers include: thermoelectric materials of a single element, such as bismuth or antimony; alloy-type thermoelectric materials, such as BiTe-type, PbTe-type and SiGe-type; and oxide-type thermoelectric materials, such as CaxCoO2, NaxCoO2and SrTiO3. In the present specification, the “thermoelectric material” refers herein to a material, of which the Seebeck coefficient has an absolute value of 30 μV/K or more and the electrical resistivity is 10 mΩcm or less. Such a thermoelectric material may be a crystalline one or an amorphous one. If the hot medium has a temperature of approximately 200 degrees Celsius or less, the thermoelectric material layers22may be made of a dense body of bismuth-antimony-tellurium, for example. Bismuth-antimony-tellurium may be, but does not have to be, represented by a chemical composition Bi0.5Sb1.5Te3. Optionally, bismuth-antimony-tellurium may include a dopant such as selenium. The mole fractions of bismuth and antimony may be adjusted appropriately.

Other examples of the thermoelectric materials to make the thermoelectric material layers22include bismuth telluride and lead telluride. When the thermoelectric material layers22are made of bismuth telluride, it may be of the chemical composition Bi2TeX, where 2<X<4. A representative chemical composition of bismuth telluride is Bi2Te3, which may include antimony or selenium. The chemical composition of bismuth telluride including antimony may be represented by (Bi1-YSbY)2TeX, where 0<Y<1, and more preferably 0.6<Y<0.9.

The first and second electrodes E1and E2may be made of any material as long as the material has good electrical conductivity. For example, the first and second electrodes E1and E2may be made of a metal selected from the group consisting of nickel, copper, silver, molybdenum, tungsten, aluminum, titanium, chromium, gold, platinum and indium. Alternatively, the first and second electrodes E1and E2may also be made of a nitrides or oxides, such as titanium nitride (TiN), indium tin oxide (ITO), and tin dioxide (SnO2). Still alternatively, the first or second electrode E1, E2may also be made of solder, silver solder or electrically conductive paste, for example. It should be noted that if both ends of the tube body Tb1are metal layers20, then the first and second electrodes E1and E2may be replaced with those metal layers20as described above.

In the foregoing description, an element with a configuration in which metal layers and thermoelectric material layers are alternately stacked one upon the other has been described as a typical example of a tubular thermoelectric generator. However, this is just an example, and the tubular thermoelectric generator which may be used according to the present disclosure does not have to have such a configuration. Rather electrical power can also be generated thermoelectrically as described above as long as a first layer made of a first material with a relatively low Seebeck coefficient and relatively high thermal conductivity and a second layer made of a second material with a relatively high Seebeck coefficient and relatively low thermal conductivity are stacked alternately one upon the other. That is to say, the metal layer20and thermoelectric material layer22are only examples of such first and second layers, respectively.

Next, look atFIGS. 7A and 7B.FIG. 7Ais a front view illustrating an exemplary thermoelectric generator unit according to an embodiment of the present disclosure.FIG. 7Billustrates one of the side faces of the thermoelectric generator unit100(a right side view in this case). As shown inFIG. 7A, the thermoelectric generator unit100according to this implementation includes a number of tubular thermoelectric generators T and a container30which houses those tubular thermoelectric generators T inside. At a glance, such a structure looks like the “shell and tube structure” of a heat exchanger. In a heat exchanger, however, a number of tubes just function as pipelines to make fluid flow through and do not have to be electrically connected together. In a thermoelectric generator unit according to the present disclosure, on the other hand, those tubular thermoelectric generators need to be electrically connected together in practice with good stability, unlike the heat exchanger.

As already described with reference toFIG. 4, a hot medium and a cold medium are supplied to the thermoelectric generator unit100. The hot medium may be supplied into the respective internal flow paths of the tubular thermoelectric generators T1to T10through multiple openings A, for example. Meanwhile, the cold medium is supplied into the container30through a fluid inlet port to be described later. As a result, a temperature difference is created between the outer and inner peripheral surfaces of each tubular thermoelectric generator T. In this case, in the thermoelectric generator unit100, not only heat is exchanged between the hot and cold media but also electromotive force occurs in the axial direction in each of the tubular thermoelectric generators T1to T10.

In this embodiment, the container30includes a cylindrical shell32which surrounds the tubular thermoelectric generators T and a pair of plates34and36which are arranged to close the open ends of the shell32. More specifically, in the example shown inFIG. 7A, the plates34and36are respectively fixed onto the left and right ends of the shell32. Each of these plates34and36has multiple openings A into which respective tubular thermoelectric generators T are inserted. Both ends of an associated tubular thermoelectric generator T are inserted into each corresponding pair of openings A of the plates34and36.

Just like the tube sheets of a shell and tube heat exchanger, these plates34and36have the function of supporting a plurality of tubes (i.e., the tubular thermoelectric generators T) so that these tubes are spatially separated from each other. As will be described in detail later, the plates34and36have an electrical connection capability that the tube sheets of a heat exchanger do not have.

Also, in the exemplary configuration shown inFIGS. 7A and 7B, a plurality of openings Cp are cut through the side peripheral surface of the pair of plates34and36, each of which has a disc shape in this example. Each of those openings Cp exposes the testing hole portion Ch of the channel C (to be described later) to the outside space. Each of the openings Cp may function as a port into which a voltage probe is inserted, for example.

Each of those openings Cp may be always open. Alternatively, to prevent water, oil, or dust from entering the testing hole portion Ch of the channel C, an openable/closable cap Cv (not shown inFIG. 7B, seeFIG. 7A) may be arranged in the vicinity of each opening Cp. Or the cap Cv may be replaced with an openable/closable shutter which is arranged inside of the plate. Into each opening Cp, a removable plug made of rubber, metal, or plastic may be inserted. If the opening Cp has a thread portion, the plug may be a screw having a thread portion that engages with the thread portion of the opening Cp. It should be noted that the number and arrangement of the openings Cp shown inFIGS. 7A and 7Bare just an example. The number of the openings Cp to provide may be changed according to the number of the tubular thermoelectric generators T housed in the container30, for example. On the drawings other thanFIG. 7A, illustration of the cap Cv is omitted.

In the example illustrated inFIG. 7A, the plate34includes a first plate portion34afixed to the shell32and a second plate portion34bwhich is attached to the first plate portion34aso as to be readily removable from the first plate portion34a. Likewise, the plate36also includes a first plate portion36afixed to the shell32and a second plate portion36bwhich is attached to the first plate portion36aso as to be readily removable from the first plate portion36a. The openings A in the plates34and36penetrate through, respectively, the first plate portions34aand36aand the second plate portions34band36b, thus leaving the flow paths of the thermoelectric generation tubes T open to the exterior of the container30.

Examples of materials to make the container30include metals such as stainless steel, HASTELLOY™ or INCONEL™. Examples of other materials to make the container30include polyvinyl chloride and acrylic resin. The shell32and the plates34,36may be made of the same material or may be made of two different materials. If the shell32and the first plate portions34aand36aare made of metal(s), then the first plate portions34aand36amay be welded onto the shell32. Or if flanges are provided at both ends of the shell32, the first plate portions34aand36amay be fixed onto those flange portions.

Since some fluid (that is either the cold medium or hot medium) is introduced into the container30while the thermoelectric generator unit100is operating, the inside of the container30should be kept either airtight or watertight. As will be described later, each opening A of the plates34,36is sealed to keep the inside of the container30either airtight or watertight once the ends of the tubular thermoelectric generator T have been inserted through the opening A. A structure in which no gap is left between the shell32and the plates34,36and which is kept either airtight or watertight throughout the operation is realized.

As shown inFIG. 7B, in this example, ten openings A have been cut through the plate36. Likewise, ten openings A have also been cut through the other plate34. In the example illustrated inFIG. 7A, each opening A of the plate34and its associated opening A of the plate36are arranged mirror-symmetrically to each other, and ten lines which connect together the respective center points of ten pairs of associated openings A are parallel to each other. According to such a configuration, the respective tubular thermoelectric generators T may be supported parallel to each other through the pairs of associated openings A. Nevertheless, those tubular thermoelectric generators T do not have to be arranged parallel to each other but may also be arranged either non-parallel or skew to each other.

As shown inFIG. 7B, the plate36has channels C, each of which has been formed to connect together at least two of the openings A cut through the plate36. In the example illustrated inFIG. 7B, the channel C61connects together openings A61and A62. Each of the other channels C62to C65also connects together two associated ones of the openings A in the plate36. In the present specification, the portion of the plate that connects together at least two of the openings A will sometimes be referred to as an “interconnection” hereinbelow. As will be described later, an electrically conductive member is housed in each of these channels C61to C65.

The channels C61to C65shown inFIG. 7Brespectively have testing hole portions Ch61to Ch65which run from the interconnections through the outer edge of the plate36. For example, a testing hole portion Ch63is provided for the channel C63so as to run straight from the interconnection Cc63through the outer edge of the plate36. Each of these testing hole portions Ch may be bent inside the plate. For example, the testing hole portion Ch may be folded or curved inside of the plate. When viewed on a plane which intersects with the direction in which the testing hole portion Ch runs at right angles, the testing hole portion Ch may have any cross-sectional shape. The cross-sectional shape of the testing hole portion Ch does not have to be uniform inside the plate and its cross-sectional area does not have to be constant inside the plate, either. For example, the cross-sectional area of the testing hole portion Ch may decrease gradually from the outer edge of the plate36toward the interconnection.

FIG. 8illustrates a portion of a cross section of the thermoelectric generator unit100as viewed on the plane M-M shown inFIG. 7B. It should be noted that inFIG. 8, a cross section of the lower half of the container30is not shown but its front portion is shown instead. As shown inFIG. 8, the container30has a fluid inlet port38aand a fluid outlet port38bthrough which a fluid flows inside the container30. In this thermoelectric generator unit100, the fluid inlet and outlet ports38aand38bare arranged in the upper part of the container30. However, the fluid inlet port38adoes not have to be arranged in the upper part of the container30but may also be arranged in the lower part of the container30as well. The same can be said about the fluid outlet port38b. The fluid inlet and outlet ports38aand38bdo not always have to be used as inlet and outlet for a fluid but may be inverted at regular or irregular intervals. That is to say, the fluid flowing direction does not have to be fixed. Also, although only one fluid inlet port38aand only one fluid outlet port38bare shown inFIG. 8, this is only an example, and more than one fluid inlet port38aand/or more than one fluid outlet port38bmay be provided as well.

FIG. 9schematically shows exemplary flow directions of the hot and cold media introduced into the thermoelectric generator unit100. In the example shown inFIG. 9, a hot medium HM is supplied into the internal flow path of each of the tubular thermoelectric generators T1to T10, while a cold medium LM is supplied into the container30. In this example, the hot medium HM is introduced into the internal flow path of each tubular thermoelectric generator through the openings A cut through the plate34. The hot medium HM introduced into the internal flow path of each tubular thermoelectric generator contacts with the inner peripheral surface of the tubular thermoelectric generator. On the other hand, the cold medium LM is introduced into the container30through the fluid inlet port38a. The cold medium LM introduced into the container30contacts with the outer peripheral surface of each tubular thermoelectric generator.

In the example shown inFIG. 9, while flowing through the internal flow path of each tubular thermoelectric generator, the hot medium HM exchanges heat with the cold medium LM. The hot medium HM, of which the temperature has decreased through heat exchange with the cold medium LM, is discharged out of the thermoelectric generator unit100through the openings A of the plate36. On the other hand, while flowing inside the container30, the cold medium LM exchanges heat with the hot medium HM. The cold medium LM, of which the temperature has increased through heat exchange with the hot medium HM, is discharged out of the thermoelectric generator unit100through the fluid outlet port38b. The flow directions of the hot and cold media HM and LM shown inFIG. 9are only an example. One or both of the hot and cold media HM and LM may flow from the right to the left on the paper.

In one implementation, the hot medium HM (e.g., hot water) may be introduced into the flow path of each tubular thermoelectric generator T, and the cold medium LM (e.g., cooling water) may be introduced through the fluid inlet port38ato fill the inside of the container30with the cold medium LM. Conversely, the cold medium LM (e.g., cooling water) may be introduced into the flow path of each tubular thermoelectric generator T, and the hot medium HM (e.g., hot water) may be introduced through the fluid inlet port38ato fill the inside of the container30with the hot medium HM. In this manner, a temperature difference which is large enough to generate electric power can be created between the outer and inner peripheral surfaces24and26of each tubular thermoelectric generator T.

<Implementations of Electrical Connection Between Tubular Thermoelectric Generators>

Portion (a) ofFIG. 10schematically illustrates a partial cross-sectional view of the plate36. Specifically, portion (a) ofFIG. 10schematically illustrates a cross section of the plate36as viewed on a plane including the respective center axes of both of two tubular thermoelectric generators T1and T2. More specifically, portion (a) ofFIG. 10illustrates the structure of openings A61and A62of multiple openings A that the plate36has and a region surrounding them. Portion (b) ofFIG. 10schematically illustrates the appearance of an electrically conductive member J1as viewed in the direction indicated by the arrow V1in portion (a) ofFIG. 10. This electrically conductive member J1has two through holes Jh1and Jh2. In detail, this electrically conductive member J1includes a first ring portion Jr1with the through hole Jh1, a second ring portion Jr2with the through hole Jh2, and a connecting portion Jc to connect these two ring portions Jr1and Jr2together.

As shown in portion (a) ofFIG. 10, one end of the tubular thermoelectric generator T1(on the second electrode side) is inserted into the opening A61of the plate36and one end of the tubular thermoelectric generator T2(on the first electrode side) is inserted into the opening A62. In this state, those ends of the tubular thermoelectric generators T1and T2are respectively inserted into the through holes Jh1and Jh2of the electrically conductive member J1. That end of the tubular thermoelectric generator T1(on the second electrode side) and that of the tubular thermoelectric generator T2(on the first electrode side) are electrically connected together via this electrically conductive member J1. In the present specification, an electrically conductive member to connect two tubular thermoelectric generators electrically together will be hereinafter referred to as a “connection plate”.

It should be noted that the first and second ring portions Jr1and Jr2do not have to have an annular shape. As long as electrical connection is established between the tubular thermoelectric generators, the through hole Jh1or Jh2may also have a circular, elliptical or polygonal shape as well. For example, the shape of the through hole Jh1or Jh2may be different from the cross-sectional shape of the first or second electrode E1or E2as viewed on a plane that intersects with the axial direction at right angles. In the present specification, the “ring” shape includes not only an annular shape but other shapes as well.

In the example illustrated in portion (a) ofFIG. 10, the first plate portion36ahas a recess R36which has been cut for the openings A61and A62. This recess R36includes a groove portion R36cto connect the openings A61and A62together. The connecting portion Jc of the electrically conductive member J1is located in this groove portion R36c. On the other hand, recesses R61and R62have been cut in the second plate portion36bfor the openings A61and A62, respectively. In this example, various members to establish sealing and electrical connection are arranged inside the space formed by these recesses R36, R61and R62. That space forms the interconnection of a channel C61to house the electrically conductive member J1and the openings A61and A62are connected together via the interconnection of the channel C61. It should be noted that a testing hole portion Ch61(not shown) is extended in the direction coming out of the paper from the space in which the second ring portion Jr2of the electrically conductive member J2is arranged.

FIG. 11Aillustrates a first plate portion36aas viewed in the direction indicated by the arrow V1in portion (a) ofFIG. 10. As shown inFIG. 11A, the electrically conductive members J can be arranged in the recesses that have been cut in the first plate portion36a. That is why by fastening the first and second plate portions36aand36btogether, the electrically conductive members J will be housed in the associated interconnections of the channels C.

As shown inFIG. 11A, the sealing surface of the first plate portion36a(i.e., the surface that faces the second plate portion36b) may have groove portions Ct which connect with the recesses. In the exemplary configuration shown inFIG. 11A, the sealing surface of the first plate portion36ahas groove portions Ct61to Ct65, which respectively run from the recesses where the electrically conductive members J1, J3, J5, J7and J9are arranged through the outer edge of the first plate portion36a. By fastening the first and second plate portions36aand36btogether, the testing hole portions Ch shown inFIG. 7Bmay be formed by the groove portions Ct of the first plate portion36aand the sealing surface of the second plate portion36b(i.e., the surface that faces the first plate portion36a). In that case, the surface of the groove portions Ct of the first plate portion36aforms part of the inner peripheral surface of the testing hole portions Ch. Those groove portions Ct running through the outer edge of the plate36may be cut on at least one of the first and second plate portions36aand36b. Optionally, the testing hole portions Ch may also be formed by cutting the groove portions Ct on both of the first and second plate portions36aand36b.

As described above, the testing hole portion Ch of each channel reaches the outer edge of the plate36. Thus, a probe for testing the tubular thermoelectric generators T can be inserted through an opening Cp that has been cut through the outer edge of the plate36. That is to say, the testing hole portion Ch can function as a slot into which the probe is inserted. As a result, the tip end of the probe can be brought into contact with the electrically conductive member J arranged in the plate36through the testing hole portion Ch.

In this case, the ends of the tubular thermoelectric generators T are inserted into the through holes of each electrically conductive member J. The electrically conductive member J and the tubular thermoelectric generators T are electrically connected together, e.g., via the electrically conductive ring members56to be described later. The electrically conductive ring members56are typically made of a metal and can thermally couple the electrically conductive member J and the tubular thermoelectric generators T together. That is why by bringing a tip end of the probe into contact with the electrically conductive member J arranged in the plate36, electrical or thermal information about the electrically conductive member J housed in the channel C can be retrieved out of this thermoelectric generator unit100.

Examples of the electrical information about the electrically conductive member J include a potential difference, electric current or electric power which has been created or generated between two arbitrary electrically conductive members J or between a certain reference point and an arbitrary electrically conductive member J. On the other hand, typical example of the thermal information about the electrically conductive member J is temperature. The potential difference, electric current and electric power can be measured with a tester, a voltmeter, an ammeter, a digital multi-meter, a source-measurement unit, a data acquisition (DAQ) unit, an electronic load or any other general instrument. The temperature may be measured with a general instrument by bringing a probe such as a thermocouple or a resistance thermometer into contact with a point of measurement.

While the thermoelectric generator unit100is operating, some failure (such as creation of cracks or bores in the tube body Tb) may occur accidentally under harsh operation conditions in any of the tubular thermoelectric generators T. In such a situation, the expected voltage cannot be obtained from the tubular thermoelectric generator T in which the failure has occurred. That is why by getting electrical information from the electrically conductive members J, decision can be made what tubular thermoelectric generator T has caused the failure. Any failure that has occurred in a tubular thermoelectric generator T can be detected as an increase in the resistance of that tubular thermoelectric generator T, for example. Also, if the hot and cold media that have been introduced into the thermoelectric generator unit100have been mixed together inside of the container30due to creation of cracks or bores in the tube body Tb, occurrence of such a failure can be detected by measuring the temperatures of the electrically conductive members J.

This thermoelectric generator unit100can seal the channels C from the fluids (hot and cold media) as will be described later. That is why decision can be made, without stopping operating the thermoelectric generator unit100, what tubular thermoelectric generator T has caused the failure.

FIG. 11Billustrates another exemplary configuration for retrieving electrical or thermal information about the electrically conductive members out of the thermoelectric generator unit100. In the example illustrated inFIG. 11B, each of the electrically conductive members Jb1, Jb3, Jb5, Jb7, and Jb9has a branch extended toward the outer edge of the plate36. Each of these branches has such a shape as matching its associated groove portion Ct on the first plate portion36aand has been fitted into the associated groove portion Ct. In the example shown inFIG. 11B, the electrically conductive member Jb1has a branch b1running from the second ring portion Jr2toward the outer edge of the plate36, for example. In one implementation, the end of this branch b1sticks out of the plate36. That is to say, the end of this branch b1sticks out of the plate36through the testing hole portion Ch61. In this example, electrical or thermal information about the electrically conductive member Jb1can be retrieved out of the thermoelectric generator unit100through the end of the branch b1. In the example shown inFIG. 11B, a portion of the electrically conductive member Jb (i.e., its branch) protrudes out of the interconnection. In the present specification, even if an electrically conductive member is “housed” in an interconnection, the profile of the electrically conductive member may not match the shape of the interconnection in this manner.

The end of the branch does not have to stick out of the plate but may be located inside of the plate. If the end of the branch is located inside of the plate, the tip end of a probe can reach the electrically conductive member (i.e., the tip end of its branch) easily even in a situation where there is a long distance from the outer edge of the plate to the interconnection (i.e., even when the slot is deep). Consequently, a relatively short probe may be used in that case.

FIGS. 12A and 12Billustrate still other exemplary configurations for retrieving electrical or thermal information about the electrically conductive members J out of the thermoelectric generator unit100. In the exemplary configuration shown inFIG. 12A, a wire W is connected to each electrically conductive member J. Each of these wires W1, W3, W5, W7, and W9has its one end electrically connected to its associated connection plate J and has the other end thereof extended out of the plate36through its associated testing hole portion Ch. If each electrically conductive member has a branch and if the end of the branch is located inside of the plate, one end of the wire W may be connected to the end of the branch with solder, for example. The portion of the wire W extended out of the plate36may be arranged along the outer edge of the plate36. The wire W typically has flexibility. In the present specification, examples of the “wire” include cords, cables and a bare metal line with no insulation jacket.

The thermoelectric generator unit100A shown inFIG. 12Aincludes a terminal box Tbx, in which the wires W extended out of the plate36are aggregated together. The terminal box Tbx has a plurality of terminals, to each of which an associated one of the wires W extended out of the plate36is connected. Thus, each of the plurality of terminals is electrically connected to an associated one of the electrically conductive members J through the testing hole portion Ch. The terminal box Tbx may be arranged at the outer edge of the plate36, for example. However, the terminal box Tbx may also be arranged at any arbitrary position and may be arranged on the side surface (side peripheral surface) of the shell32, for example. The terminal box Tbx may even be arranged distant from the location where the thermoelectric generator unit100A is arranged. By aggregating such wires each of which is connected to an associated one of the electrically conductive members J, in the terminal box Tbx, electrical information about the electrically conductive members J can be collected even more easily.

The testing hole portion Ch may have a ramified portion inside of the plate36. In the thermoelectric generator unit100B shown inFIG. 12B, two groove portions Ct63and Ct64of the first plate portion36aare joined together at a ramified portion Br inside the plate36. Also, a wire W5, one end of which is connected to the electrically conductive member J5, and a wire W7, one end of which is connected to the electrically conductive member J7, are extended out of the plate36through the same opening. As can be seen, if a testing hole portion Ch has such a ramified portion Br inside of the plate36, the layout of the wires between the electrically conductive members J and the terminal box Tbx can be simplified.

In the exemplary configurations shown inFIGS. 11A, 11B, 12A and 12B, each testing hole portion Ch (or groove portion Ct) runs straight from the interconnection through the outer edge of the plate36. However, the testing hole portion Ch may also wind inside of the plate36. For example, if groove portions Ct are formed so as to draw curves inside of the plate36, the openings Cp to expose the testing hole portions Ch to the outside space can be aggregated together at a single position. Alternatively, more than one ramified portion Br may be provided inside of the plate36and all of the wires W may be extended out of the plate36through the same opening Cp.

It should be noted that if each electrically conductive member has a branch, the branch may have such a shape as matching the shape of its associated groove portion Ct. That is to say, the branch does not have to run straight. Also, if the end of the branch sticks out of the plate36, the portion sticking out of the plate36may run along the outer edge of the plate36. For example, part of the branch of the electrically conductive member sticking out of the plate36may be arranged along the outer edge of the plate36and may be electrically connected to an associated one of the terminals in the terminal box just like the wire W shown inFIG. 12A or 12B.

<Implementation of Sealing from Fluid>

Now look atFIG. 10again. In the example illustrated in portion (a) ofFIG. 10, not only the electrically conductive member J1but also a first O-ring52a, washers54, an electrically conductive ring member56and a second O-ring52bare housed in the channel C61. The respective ends of the tubular thermoelectric generators T1and T2go through the holes of these members. The first O-ring52aarranged closest to the shell32of the container30is in contact with the seating surface Bsa that has been formed in the first plate portion36aand establishes sealing so as to prevent a fluid that has been supplied into the shell32from entering the channel C61. On the other hand, the second O-ring52barranged most distant from the shell32of the container30is in contact with a seating surface Bsb that has been formed in the second plate portion36band establishes sealing so as to prevent a fluid located outside of the second plate portion36bfrom entering the channel C61.

The O-rings52aand52bare annular seal members with an O (i.e., circular) cross section. The O-rings52aand52bmay be made of rubber, metal or plastic, for example, and have the function of preventing a fluid from leaking out, or flowing into, through a gap between the members. In portion (a) ofFIG. 10, there is a space which communicates with the flow paths of the respective tubular thermoelectric generators T on the right-hand side of the second plate portion36band there is a fluid (the hot or cold medium in this example) in that space. According to this embodiment, by using the members shown inFIG. 10, electrical connection between the tubular thermoelectric generators T and sealing from the fluids (the hot and cold media) are established. The structure and function of the electrically conductive ring member56will be described in detail later.

The same members as the ones described for the plate36are provided for the plate34, too. Although the respective openings A of the plates34and36are arranged mirror symmetrically, the groove portions connecting any two openings A together on the plate34are not arranged mirror symmetrically with the groove portions connecting any two openings A together on the plate36. If the arrangement patterns of the electrically conductive members to electrically connect the tubular thermoelectric generators T together on the plates34and36, were mirror symmetric to each other, then those tubular thermoelectric generators T could not be connected together in series. It should be noted that the testing hole portions Ch of the channels C of the plate34do not have to be arranged mirror symmetrically with the testing hole portions Ch of the channels C of the plate36, either.

If a plate (such as the plate36) fixed onto the shell32includes first and second plate portions (36aand36b) as in this embodiment, each of the multiple openings A cut through the first plate portion (36a) has a first seating surface (Bsa) associated therewith to receive the first O-ring52a, and each of the multiple openings A cut through the second plate portion (36b) has a second seating surface (Bsb) to receive the second O-ring52b. However, the plates34and36do not need to have the configuration shown inFIG. 10and the plate36does not have to be divided into the first and second plate portions36aand36b, either. If the electrically conductive member J1is pressed by another member instead of the second plate portion36b, the respective first O-rings52apress against the first seating surface (Bsa) to establish sealing, too.

In the example shown in portion (a) ofFIG. 10, the electrically conductive ring member56is interposed between the tubular thermoelectric generator T1and the electrically conductive member J1. Likewise, another electrically conductive ring member56is interposed between the tubular thermoelectric generator T2and the electrically conductive member J1, too.

The electrically conductive member J1is typically made of a metal. Examples of materials to make the electrically conductive member J1include copper (oxygen-free copper), brass and aluminum. The material may be plated with nickel or tin for anticorrosion purposes. As long as electrical connection is established between the electrically conductive member J (e.g., J1in this example) and the tubular thermoelectric generators T (e.g., T1and T2in this example) inserted into the two through holes of the electrically conductive member J (e.g., Jh1and Jh2in this example), the electrically conductive member J may be partially coated with an insulator. That is to say, the electrically conductive member J may include a body made of a metallic material and an insulating coating which covers the surface of the body at least partially. The insulating coating may be made of a resin such as TEFLON™, for example. If the body of the electrically conductive member J is made of aluminum, the surface may be partially coated with an oxide skin as an insulating coating. If the electrically conductive member J has an insulating coating on its surface, the insulating coating just needs to be removed from a portion to contact with the probe, for example.

FIG. 13Ais an exploded perspective view schematically illustrating the channel C61to house the electrically conductive member J1and its vicinity. As shown inFIG. 13A, the first O-rings52a, electrically conductive ring members56, electrically conductive member J1and second O-rings52bare inserted into the openings A61and A62from outside of the container30. In this example, washers54are arranged between the first O-rings52aand the electrically conductive ring members56. Washers54may also be arranged between the electrically conductive member J1and the second O-rings52b. The washers54are inserted between the flat portions56fof the electrically conductive ring members56to be described later and the O-rings52a(or52b).

In the example illustrated inFIG. 13A, the groove portion Ct61runs from a portion of the recess R36associated with the second ring portion Jr2of the electrically conductive member J1. However, the groove portion Ct61may run from a portion of the recess R36associated with the first ring portion Jr1of the electrically conductive member J1or from a portion of the recess R36associated with the connection portion Jc of the electrically conductive member J1. The direction in which the groove portion Ct61runs may be determined arbitrarily.

As shown inFIG. 13A, the electrically conductive member (connection plate) J may have a threaded hole Sh which has been cut parallel to the direction in which the testing hole portion Ch runs. By cutting the threaded hole Sh in the electrically conductive member J, a wire W and the electrically conductive member J can be fixed to each other with a screw via a solderless terminal attached to the tip end of the wire W. Alternatively, a metallic bar with a thread portion at its tip end may be inserted and screwed into the threaded hole Sh of the electrically conductive member J and used as the branch of the electrically conductive member J. Optionally, the metallic bar may be fixed by solder to the electrically conductive member J.

FIG. 13Bschematically illustrates a portion of the sealing surface of the second plate portion36b(i.e., the surface that faces the first plate portion36a) associated with the openings A61and A62. As described above, the openings A61and A62of the second plate portion36beach have a seating surface Bsb to receive the second O-ring52b. That is why if the respective sealing surfaces of the first and second plate portions36aand36bare arranged to face each other and fastened together by flange connection, for example, the first O-rings52ain the first plate portion36acan be pressed against the seating surfaces Bsa. More specifically, the second seating surfaces Bsb press the first O-rings52aagainst the seating surfaces Bsa through the second O-rings52b, electrically conductive member J1and electrically conductive ring members56. In this manner, the electrically conductive member J1can be sealed from the hot and cold media.

If the first and second plate portions36aand36bare made of an electrically conductive material such as a metal, then the sealing surfaces of the first and second plate portions36aand36bmay be coated with an insulator material. Parts of the first and second plate portions36aand36bto contact with the electrically conductive member J during operation may be coated with an insulator so as to be electrically insulated from the electrically conductive member J. Likewise, parts of the first and second plate portions36aand36bto contact with the wire W during operation may be coated with an insulator so as to be electrically insulated from the wire W. If the first or second plate portion36aor36bhas a groove portion Ct, the surface of the groove portion Ct may also be coated with an insulator. In this manner, an insulating coating which covers the inner peripheral surface of the testing hole portion Ch can be formed. In one implementation, the sealing surfaces of the first and second plate portions36aand36bmay be sprayed and coated with a fluoroethylene resin.

<Detailed Configuration for Electrically Conductive Ring Members>

A detailed configuration for the electrically conductive ring members56will be described with reference toFIGS. 14A and 14B.

FIG. 14Ais a perspective view illustrating an exemplary shape of an electrically conductive ring member56. The electrically conductive ring member56shown inFIG. 14Aincludes a ringlike flat portion56fand a plurality of elastic portions56r. The flat portion56fhas a through hole56a. Those elastic portions56rproject from around the periphery of the through hole56aof the flat portion56fand are biased toward the center of the through hole56awith elastic force. Such an electrically conductive ring member56can be made easily by patterning a single metallic plate (with a thickness of 0.1 mm to a few mm, for example). Likewise, the electrically conductive members J can also be made easily by patterning a single metallic plate (with a thickness of 0.1 mm to a few mm, for example).

An end (on the first or second electrode side) of an associated tubular thermoelectric generator T is inserted into the through hole56aof each electrically conductive ring member56. That is why the shape and size of the through hole56aof the ringlike flat portion56fare designed so as to match the shape and size of the outer peripheral surface of that end (on the first or second electrode side) of the tubular thermoelectric generator T.

Next, the shape of the electrically conductive ring member56will be described in further detail with reference toFIGS. 15A, 15B and 15C.FIG. 15Ais a cross-sectional view schematically illustrating portions of the electrically conductive ring member56and tubular thermoelectric generator T1.FIG. 15Bis a cross-sectional view schematically illustrating a state where an end of the tubular thermoelectric generator T1has been inserted into the electrically conductive ring member56. AndFIG. 15Cis a cross-sectional view schematically illustrating a state where an end of the tubular thermoelectric generator T1has been inserted into the respective through holes of the electrically conductive ring member56and electrically conductive member J1. The cross sections illustrated inFIGS. 15A, 15B and 15Care viewed on a plane including the axis (i.e., the center axis) of the tubular thermoelectric generator T1.

Suppose the outer peripheral surface of the tubular thermoelectric generator T1at that end (on the first or second electrode side) is a circular cylinder with a diameter D as shown inFIG. 15A. In that case, the through hole56aof the electrically conductive ring member56is formed in a circular shape with a diameter D+δ1 (where δ1>1) so as to pass the end of the tubular thermoelectric generator T1. On the other hand, the respective elastic portions56rhave been formed so that biasing force is applied toward the center of the through hole56a. The respective elastic portions56rmay be formed so as to be tilted toward the center of the through hole56aas shown inFIG. 15A. That is to say, the elastic portions56rhave been shaped so as to be circumscribed with the outer peripheral surface of a circular cylinder, of which a cross section has a diameter that is smaller than D (and that is represented by D−δ2 (where δ2>0)) unless any external force is applied.

D+δ1>D>D−δ2 is satisfied. That is why when the end of the tubular thermoelectric generator T1is inserted into the through hole56a, the respective elastic portions56rare brought into physical contact with the outer peripheral surface at the end of the tubular thermoelectric generator T1as shown inFIG. 15B. In this case, since elastic force is applied to the respective elastic portions56rtoward the center of the through hole56a, the respective elastic portions56rpress the outer peripheral surface at the end of the tubular thermoelectric generator T1with the elastic force. In this manner, the outer peripheral surface of the tubular thermoelectric generator T1inserted into the through hole56aestablishes stabilized physical and electrical contact with those elastic portions56r.

Next, look atFIG. 15C. Inside the opening A cut through the plate34,36, the electrically conductive member J1contacts with the flat portion56fof the electrically conductive ring member56. More specifically, when the end of the tubular thermoelectric generator T1is inserted into the electrically conductive ring member56and electrically conductive member J1, the surface of the flat portion56fof the electrically conductive ring member56contacts with the surface of the ring portion Jr1of the electrically conductive member J1as shown inFIG. 15C. As can be seen, in this embodiment, the electrically conductive ring member56and the electrically conductive member J1may be electrically connected together by bringing their planes into contact with each other. Since the electrically conductive ring member56and the electrically conductive member J1contact with each other on their planes, a contact area which is large enough to make the electric current generated in the tubular thermoelectric generator T1flow can be secured. The width w of the flat portion56fis set appropriately to secure a contact area which is large enough to make the electric current generated in the tubular thermoelectric generator T1flow. As long as a contact area can be secured between the electrically conductive ring member56and the electrically conductive member J1, either the surface of the flat portion56for the surface of the ring portion Jr1of the electrically conductive member J1may have some unevenness. For example, an even larger area of contact can be secured by making the surface of the ring portion Jr1of the electrically conductive member J1have an embossed pattern matching the one on the surface of the flat portion56f.

Next, look atFIGS. 16A and 16B.FIG. 16Ais a cross-sectional view schematically illustrating the electrically conductive ring member56and a portion of the electrically conductive member J1.FIG. 16Bis a cross-sectional view schematically illustrating a state where the elastic portions56rof the electrically conductive ring member56have been inserted into the through hole Jh1of the electrically conductive member J1. The cross sections shown inFIGS. 16A and 16Bare obtained by viewing the electrically conductive ring member56and the electrically conductive member J1on a plane including the axis (center axis) of the tubular thermoelectric generator T1.

If the diameter of the through hole (e.g., Jh1in this case) of the electrically conductive member J is supposed to be 2Rr, the through hole of the electrically conductive member J is formed to satisfy D<2Rr (i.e., so as to pass the end of the tubular thermoelectric generator T1through itself). Also, if the diameter of the flat portion56fof the electrically conductive ring member56is supposed to be 2Rf, the through hole of the electrically conductive member J is formed to satisfy 2Rr<2Rf so that the respective surfaces of the flat portion56fand ring portion Jr1contact with each other just as intended.

Optionally, the end of the tubular thermoelectric generator T may have a chamfered portion Cm as shown inFIG. 17. The reason is that when the end of the tubular thermoelectric generator T (e.g., tubular thermoelectric generator T1) is inserted into the through hole56aof the electrically conductive ring member56, the elastic portions56rof the electrically conductive ring member56and the end of the tubular thermoelectric generator T contact with each other, thus possibly getting the end of the tubular thermoelectric generator T damaged. However, by providing such a chamfered portion Cm at the end of the tubular thermoelectric generator T, such damage that could be done on the end of the tubular thermoelectric generator T due to the contact between the elastic portions56rand the end of the tubular thermoelectric generator T can be avoided. And by avoiding the occurrence of the damage on the end of the tubular thermoelectric generator T, the electrically conductive member J1can be sealed more securely from the hot and cold media. In addition, electrical contact failure between the outer peripheral surface of the tubular thermoelectric generator T1and the elastic portions56rcan also be reduced. The chamfered portion Cm may have the curved surface as shown inFIG. 17or may also have a planar surface.

And the electrically conductive member J1contacts with the flat portion56fof the electrically conductive ring member56inside of the openings A of the plate. More specifically, the surface of the first ring portion Jr1(or the second ring portion Jr2) of the electrically conductive member J1and the surface of the flat portion56fof the electrically conductive ring member56contact with each other. In this manner, the electrically conductive member J1is electrically connected to the outer peripheral surface at the end of the tubular thermoelectric generator T via the electrically conductive ring member56. According to this embodiment, by fastening the first and second plate portions36aand36btogether, the flat portion56fof the electrically conductive ring member56and the electrically conductive member J can make electrical contact with each other with good stability and sealing described above can be established.

Next, it will be described how the electrically conductive ring member56may be fitted into the tubular thermoelectric generator T.

First of all, as shown inFIG. 13A, the respective ends of the tubular thermoelectric generators T1and T2are inserted into the openings A61and A62of the first plate portion36a. After that, the first O-rings52a(and the washers54if necessary) are fitted into the tubular thermoelectric generators through their tip ends and pushed deeper into the openings A61and A62. Next, the electrically conductive ring members56are fitted into the tubular thermoelectric generators through their tip ends and pushed deeper into the openings A61and A62. Subsequently, the electrically conductive member J1(and the washers54and second O-rings52bif necessary) is/are fitted into the tubular thermoelectric generators through their tip ends and pushed deeper into the openings A61and A62. In this case, the electrically conductive member J1is arranged between the first and second O-rings52aand52binside the channel. Finally, the sealing surface of the second plate portion36bis arranged to face the first plate portion36aand the first and second plate portions36aand36bare fastened together by flange connection, for example, so that the respective tip ends of the tubular thermoelectric generators are inserted into the openings of the second plate portion36b. In this case, the first and second plate portions36aand36bmay be fastened together with bolts and nuts through the holes36bhcut through the second plate portion36b(shown inFIG. 7B) and the holes cut through the first plate portion36a.

The electrically conductive ring member56is not connected permanently to, and is readily removable from, the tubular thermoelectric generator T. For example, when the tubular thermoelectric generator T is replaced with a new tubular thermoelectric generator T, to remove the electrically conductive ring member56from the tubular thermoelectric generator T, the operation of fitting the electrically conductive ring members56into the tubular thermoelectric generators T may be performed in reverse order. The electrically conductive ring member56may be used a number of times (i.e., is recyclable) or replaced with a new one.

The electrically conductive ring member56does not always have to have the exemplary shape shown inFIG. 14A. The ratio of the width of the flat portion56f(as measured radially) to the radius of the through hole56amay also be defined arbitrarily. The respective elastic portions56rmay have any of various shapes and the number of the elastic portions56rto provide may be set arbitrarily, too.

FIG. 14Bis a perspective view illustrating another exemplary shape of the electrically conductive ring member56. The electrically conductive ring member56shown inFIG. 14Balso has a ringlike flat portion56fand a plurality of elastic portions56r. The flat portion56fhas a through hole56a. Each of the elastic portions56rprojects from around the through hole56aof the flat portion56fand is biased toward the center of the through hole56awith elastic force. In this example, the number of the elastic portions56rto provide is four. The number of the elastic portions56rmay be two but is suitably three or more. For example, six or more elastic portions56rmay be provided.

It should be noted that according to such an arrangement in which the flat-plate electrically conductive member J is brought into contact with the flat portion56fof the electrically conductive ring member56, some gap (or clearance) may be left between the through hole inside the ring portion of the electrically conductive member J and the tubular thermoelectric generator to be inserted into the hole. Thus, even if the tubular thermoelectric generator is made of a brittle material, the tubular thermoelectric generator can also be connected with good stability without allowing the ring portion Jr1of the electrically conductive member J to do damage on the tubular thermoelectric generator.

<Electrical Connection Via Connection Plate>

As described above, the electrically conductive member (connection plate) is housed inside the channel C (i.e., inside the interconnection of the channel C) which has been cut to interconnect at least two of the openings A that have been cut through the plate36. Note that the respective ends of the two tubular thermoelectric generators may be electrically connected together without the electrically conductive ring members56. In other words, the electrically conductive ring members56may be omitted from the channel C. In that case, the respective ends of the two tubular thermoelectric generators may be electrically connected together via an electric cord, a conductor bar, or electrically conductive paste, for example. If the ends of the two tubular thermoelectric generators are electrically connected together via an electric cord, those ends of the tubular thermoelectric generators and the cord may be electrically connected together by soldering, crimping or crocodile-clipping, for example. In such a case, by inserting the probe into the testing hole portion Ch and bringing the tip end of the probe into contact with the first electrode E1or second electrode E2of the tubular thermoelectric generator T, electrical or thermal information about the tubular thermoelectric generator T can be retrieved out of the thermoelectric generator unit.

However, as shown inFIGS. 10 and 13A, by electrically connecting the respective ends of the two tubular thermoelectric generators via the electrically conductive member that is housed in the channel C, the those ends of the tubular thermoelectric generators T can be electrically connected together more stably. If the electrically conductive member J has a flat plate shape (e.g., if the connecting portion Jc has a broad width), the electrical resistance between the two tubular thermoelectric generators can be reduced compared to a situation where an electric cord is used. In addition, since no terminals are fixed onto the ends of the tubular thermoelectric generators T, the tubular thermoelectric generators T can be replaced easily. With the electrically conductive ring members56, the respective ends of the two tubular thermoelectric generators can be not only fixed to each other but also electrically connected together.

In the thermoelectric generator unit100of the present disclosure, the plate34or36has the channel C which has been cut to connect together at least two of the openings A, and therefore, electrical connecting function which has never been provided by any tube sheet for a heat exchanger is realized. In addition, since the thermoelectric generator unit100can be configured so that the first and second O-rings52aand52bpress the seating surfaces Bsa and Bsb, respectively, sealing can be established so that either airtight or watertight condition is maintained with the ends of the tubular thermoelectric generators T inserted. By providing the channel C for the plate34or36, even in an implementation in which the electrically conductive ring members56are omitted, the ends of the two tubular thermoelectric generators can also be electrically connected together and sealing from the fluids (e.g., the hot and cold media) can also be established.

<Relation Between Direction of Flow of Heat and Tilt Direction of Planes of Stacking>

Now, the relation between the direction of flow of heat in each thermoelectric generation tube T and the tilt direction of the planes of stacking in the thermoelectric generation tube T will be described with reference toFIGS. 18A and 18B.

FIG. 18Aschematically illustrates how electric current flows in tubular thermoelectric generators T which are electrically connected together in series.FIG. 18Aschematically illustrates cross sections of three (T1to T3) of the tubular thermoelectric generators T1to T10.

InFIG. 18A, an electrically conductive member (terminal plate) K1is connected to one end of the tubular thermoelectric generator T1(e.g., at the first electrode end), while an electrically conductive member (connection plate) J1is connected to the other end (e.g., at the second electrode end) of the tubular thermoelectric generator T1. The electrically conductive member J1is also connected to one end (i.e., at the first electrode end) of the tubular thermoelectric generator T2. As a result, the tubular thermoelectric generators T1and T2are electrically connected together. Furthermore, the other end (i.e., at the second electrode end) of the tubular thermoelectric generator T2and one end (i.e., at the first electrode end) of the tubular thermoelectric generator T3are electrically connected together via the electrically conductive member J2.

In this case, as shown inFIG. 18A, the tilt direction of the planes of stacking in the tubular thermoelectric generator T2is opposite from the tilt direction of the planes of stacking in the tubular thermoelectric generator T1. Likewise, the tilt direction of the planes of stacking in the tubular thermoelectric generator T3is opposite from the tilt direction of the planes of stacking in the tubular thermoelectric generator T2. That is to say, in this thermoelectric generator unit100, each of the tubular thermoelectric generator T1to T10has planes of stacking that is tilted in the opposite direction from those of an adjacent one of the tubular thermoelectric generators that is connected to itself via a connection plate.

Suppose the hot medium HM has been brought into contact with the inner peripheral surface of each of the tubular thermoelectric generators T1to T3, and the cold medium LM has been brought into contact with their outer peripheral surface, as shown inFIG. 18A. In that case, in the tubular thermoelectric generator T1, electric current flows from the right to the left on the paper, for example. On the other hand, in the tubular thermoelectric generator T2, of which the planes of stacking are tilted in the opposite direction from those of the tubular thermoelectric generator T1, electric current flows from the left to the right on the paper.

FIG. 19schematically shows the directions in which electric current flows through the two openings A61and A62and their surrounding region.FIG. 19is a drawing corresponding to portion (a) ofFIG. 10. InFIG. 19, the flow directions of the electric current are schematically indicated by the dotted arrows. As shown inFIG. 19, the electric current generated in the tubular thermoelectric generator T1flows toward the tubular thermoelectric generator T2through the electrically conductive ring member56of the opening A61, the electrically conductive member J1and the electrically conductive ring member56of the opening A62in this order. The electric current that has flowed into the tubular thermoelectric generator T2is combined with electric current generated in the tubular thermoelectric generator T2, and the electric current thus combined flows toward the tubular thermoelectric generator T3. As shown inFIG. 18A, the planes of stacking of the tubular thermoelectric generator T3are tilted in the opposite direction from those of the tubular thermoelectric generator T2. That is why in the tubular thermoelectric generator T3, the electric current flows from the right to the left inFIG. 18A. Consequently, the electromotive forces generated in the respective tubular thermoelectric generators T1to T3get superposed one upon the other without canceling each other. By sequentially connecting a plurality of tubular thermoelectric generators T together in this manner so that the tilt direction of their planes of stacking inverts alternately one generator after another, an even greater voltage can be extracted from the thermoelectric generator unit.

Next, look atFIG. 18B, which also schematically shows, just likeFIG. 18A, electric current flowing through tubular thermoelectric generators T which are electrically connected in series. As in the example shown inFIG. 18A, the tubular thermoelectric generators T1to T3are also sequentially connected inFIG. 18Bso that the tilt direction of their planes of stacking inverts alternately one generator after another. In this case, since the planes of stacking in one of any two adjacent tubular thermoelectric generators connected together are tilted in the opposite direction from the planes of stacking in the other tubular thermoelectric generator, the electromotive forces generated in the respective tubular thermoelectric generators T1to T3get superposed one upon the other without canceling each other.

If the cold medium LM is brought into contact with the inner peripheral surface of each of the tubular thermoelectric generators T1to T3and the hot medium HM is brought into contact with their outer peripheral surface as shown inFIG. 18B, the polarity of voltage generated in each of the tubular thermoelectric generators T1to T3becomes opposite from the one shown inFIG. 18A. In other words, if the direction of the temperature gradient in each tubular thermoelectric generator is inverted, then the polarity of the electromotive force in that tubular thermoelectric generator (which may also be called the direction of electric current flowing through that tubular thermoelectric generator) inverts. Therefore, to make electric current flow from the electrically conductive member K1toward the electrically conductive member J3as inFIG. 18A, the configurations on the first and second electrode sides in each of the tubular thermoelectric generators T1to T3may be opposite from the configurations shown inFIG. 18A. It should be noted that electric current flow directions shown inFIGS. 18A and 18Bare just examples. Depending on the material to make the metal layers20and the thermoelectric material to make the thermoelectric material layers22, the electric current flow directions may be opposite from the ones shown inFIGS. 18A and 18B.

As already described with reference toFIGS. 18A and 18B, the polarity of the voltage generated in the tubular thermoelectric generator T depends on the tilt direction of the planes of stacking of that tubular thermoelectric generator T. That is why when the tubular thermoelectric generator T is going to be replaced, for example, the tubular thermoelectric generator T needs to be arranged appropriately with the temperature gradient between the inner and outer peripheral surfaces of the tubular thermoelectric generator T in the thermoelectric generator unit100taken into account.

FIGS. 20A and 20Bare perspective views each illustrating an exemplary tubular thermoelectric generator, of which the electrodes have indicators of their polarity. In the tubular thermoelectric generator T shown inFIG. 20A, molded portions (embossed marks) Mp indicating the polarity of the voltage generated in the tubular thermoelectric generator have been formed on the first and second electrodes E1aand E2a. On the other hand, in the tubular thermoelectric generator T shown inFIG. 20B, marks Mk indicating whether the planes of stacking in the tubular thermoelectric generator T are tilted toward the first electrode E1bor the second electrode E2bare left on the first and second electrodes E1band E2b. These molded portions (e.g., convex or concave portions) and marks may be combined together. Optionally, these molded portions and marks may be added to the tube body Tb or to only one of the first and second electrodes.

In this manner, molded portions or marks indicating the polarity of the voltage generated in the tubular thermoelectric generator T may be added to the first and second electrodes, for example. In that case, it can be seen quickly just from the appearance of the tubular thermoelectric generator T whether the planes of stacking of the tubular thermoelectric generator T are tilted toward the first electrode or the second electrode. Optionally, instead of adding such molded portions or marks, the first and second electrodes may have mutually different shapes. For example, the lengths, thicknesses or cross-sectional shapes as viewed on a plane that intersects with the axial direction at right angles may be different from each other between the first and second electrodes.

<Electrical Connection Structure for Taking Electric Power Out of Thermoelectric Generator Unit100>

Now look atFIG. 5again. In the example illustrated inFIG. 5, ten tubular thermoelectric generators T1to T10are electrically connected in series via electrically conductive members J1to J9. Each of these electrically conductive members J1to J9connects its associated two tubular thermoelectric generators T together just as described above. An exemplary electrical connection structure for taking electric power out of the thermoelectric generator unit100from the two tubular generators T1and T10located at both ends of the series circuit will now be described.

First, look atFIG. 21, which illustrates the other side face of the thermoelectric generator unit100shown inFIG. 7A(left side view). WhileFIG. 7Bshows a configuration for the plate36,FIG. 21shows a configuration for the plate34. Any member or operation that has already been described with respect to the plate36will not be described all over again to avoid redundancies.

As shown inFIG. 21, each of the channels C42to C45interconnects at least two of the openings A cut through the plate34. The electrically conductive members housed in the interconnections may have the same configuration as the electrically conductive member J1. On the other hand, the channel C41is provided for the plate34so as to run from the opening A41to the outer edge of the plate34. In the present specification, such a channel provided to run from an opening of a plate to its outer edge will sometimes be referred to as a “terminal connection” hereinbelow. The channels C41and C46shown inFIG. 21are terminal connections. In each terminal connection, the electrically conductive member functioning as a terminal for connecting to an external circuit is housed.

The channels C42to C45shown inFIG. 21respectively have testing hole portions Ch42to Ch45which run from the interconnections through the outer edge of the plate34. For example, the testing hole portion Ch42of the channel C42is arranged so as to run straight from the interconnection Cc42through the outer edge of the plate34. Thus, a test probe for the tubular thermoelectric generator T can be inserted into the opening Cp cut through the outer edge of the plate34.

Portion (a) ofFIG. 22is a schematic partial cross-sectional view of the plate34. Specifically, portion (a) ofFIG. 22schematically illustrates a cross section of the plate as viewed on a plane including the center axis of the tubular thermoelectric generator T1and corresponding to the plane R-R′ shown inFIG. 21. More specifically, portion (a) ofFIG. 22illustrates the structure of one A41of multiple openings A that the plate34has and a region surrounding it. Portion (b) ofFIG. 22illustrates the appearance of an electrically conductive member K1as viewed in the direction indicated by the arrow V2in portion (a) ofFIG. 22. This electrically conductive member K1has a through hole Kh at one end. More specifically, this electrically conductive member K1includes a ring portion Kr with the through hole Kh and a terminal portion Kt extending outward from the ring portion Kr. Just like the electrically conductive member J1, this electrically conductive member K1is also typically made of a metal. In the present specification, an electrically conductive member, one end of which receives a tubular thermoelectric generator inserted and the other end of which sticks out, will sometimes be referred to as a “terminal plate” hereinbelow.

As shown in portion (a) ofFIG. 22, one end of the tubular thermoelectric generator T1(on the first electrode side) is inserted into the opening A41of the plate34. In this state, the end of the tubular thermoelectric generator T1is inserted into the through hole Kh of the electrically conductive member K1. As can be seen, an electrically conductive member J or K1according to this embodiment can be said to be an electrically conductive plate with at least one hole to pass the tubular thermoelectric generator T through. The structure of the opening A410and the region surrounding it is the same as that of the opening A41and the region surrounding it except that the end of the tubular thermoelectric generator T10is inserted into the opening A410of the plate34.

In the example illustrated in portion (a) ofFIG. 22, the first plate portion34ahas a recess R34which has been cut for the opening A41. This recess R34includes a groove portion R34twhich extends from the opening A41through the outer edge of the first plate portion34a. In this groove portion R34t, located is the terminal portion Kt of the electrically conductive member K1. In this example, the space defined by the recess R34and a recess R41which has been cut in the second plate portion34bforms a channel to house the electrically conductive member K1. As in the example illustrated in portion (a) ofFIG. 10, not only the electrically conductive member K1but also a first O-ring52a, washers54, an electrically conductive ring member56and a second O-ring52bare housed in the channel C41in the example illustrated in portion (a) ofFIG. 22, too. And the end of the tubular thermoelectric generator T1goes through the holes of these members. The first O-ring52aestablishes sealing so as to prevent a fluid that has been supplied into the shell32from entering the channel C41. On the other hand, the second O-ring52bestablishes sealing so as to prevent a fluid located outside of the second plate portion34bfrom entering the channel C41.

FIG. 23illustrates the first plate portion34aas viewed in the direction indicated by the arrow V2in portion (a) ofFIG. 22. As shown inFIG. 23, the electrically conductive members J or K can be arranged in the recesses that have been cut on the first plate portion34a. That is why by fastening the first and second plate portions34aand34btogether, the electrically conductive members (connection plates) J2, J4, J6, and J8are housed in the interconnections of the channels C, and the electrically conductive members (terminal plates) K1and K10are housed in the terminal connections of the channels C.

As shown inFIG. 23, the sealing surface of the first plate portion34a(i.e., its surface that faces the second plate portion34b) may have groove portions Ct that connect with the recesses. In the exemplary configuration shown inFIG. 23, the groove portions Ct42to Ct45run from the recesses in which the electrically conductive members J2, J4, J6, and J8are arranged through the outer edge of the first plate portion34a. It should be noted that the space (i.e., hole portion) defined by the groove portion R34tin which the terminal portion Kt of the electrically conductive member K1is arranged and the sealing surface of the second plate portion34b(i.e., its surface that faces the first plate portion34a) does not run from any interconnection, which is different from the testing hole portion Ch.

Optionally, a terminal box Tbx such as the ones shown inFIGS. 12A and 12Bmay be arranged at the outer edge of the plate34. The terminal box Tbx may be arranged either at the respective outer edges of both of the plates34and36or only at the outer edge of one of the plates34and36. For example, the wires W extended out of the plate34may be connected to the terminals in the terminal box Tbx arranged at the outer edge of the plate36. If the wires W extended out of the plate34and the wires W extended out of the plate36are aggregated together at the same location, there is no need to insert probes into the respective testing hole portions Ch of the plates34and36at the same time. Consequently, decision can be made more easily what tubular thermoelectric generator T has caused a failure.

FIG. 24is an exploded perspective view schematically illustrating the channel C41to house the electrically conductive member K1and its vicinity. For example, a first O-ring52a, a washer54, an electrically conductive ring member56, the electrically conductive member K1, another washer54and a second O-ring52bmay be inserted into the opening A41from outside of the container30. The sealing surface of the second plate portion34b(i.e., the surface that faces the first plate portion34a) has substantially the same configuration as the sealing surface of the second plate portion36bshown inFIG. 13B. Thus, by fastening the first and second plate portions34aand34btogether, the second seating surface Bsb of the second plate portion34bpresses the first O-ring52aagainst the seating surface Bsa of the first plate portion34athrough the second O-ring52b, electrically conductive member K1and electrically conductive ring member56. In this manner, the electrically conductive member K1can be sealed from the hot and cold media.

The ring portion Kr of the electrically conductive member K1contacts with the flat portion56fof the electrically conductive ring member56inside the opening A cut through the plate34. In this manner, the electrically conductive member K1is electrically connected to the outer peripheral surface at the end of the tubular thermoelectric generator T via the electrically conductive ring member56. In this case, one end of the electrically conductive member K1(i.e., the terminal portion Kt) sticks out of the plate34as shown in portion (a) ofFIG. 22. Thus, that part of the terminal portion Kt that sticks out of the plate34may function as a terminal to connect the thermoelectric generator unit to an external circuit. In addition, through that part of the terminal portion Kt that sticks out of the plate34, electrical or thermal information about the electrically conductive member K (e.g., K1in this example) can be retrieved out of the thermoelectric generator unit100. As shown inFIG. 24, that part of the terminal portion Kt to stick out of the plate34may have a ring shape.

As described above, in a thermoelectric generator unit according to the present disclosure (e.g., the thermoelectric generator unit100in this example), the tubular thermoelectric generators T1and T10are respectively connected to the two terminal plates housed in the terminal connections. In addition, between those two terminal plates, those tubular thermoelectric generators T1through T10are electrically connected together in series via the connection plate housed in the interconnection of the channel. Consequently, through the two terminal plates, one end of which sticks out of the plate (34,36), the electric power generated by those tubular thermoelectric generators T1to T10can be taken out of this thermoelectric generator unit100.

The arrangements of the electrically conductive ring member56and electrically conductive member J, K1may be changed appropriately inside the channel C. In that case, the electrically conductive ring member56and the electrically conductive member (J, K1) just need to be arranged so that the elastic portions56rof the electrically conductive ring member56are inserted into the through hole Jh1, Jh2or Kh of the electrically conductive member. Also, as mentioned above, in an implementation in which the electrically conductive ring member56is omitted, the end of the tubular thermoelectric generator T may be electrically connected to the electrically conductive member K1. Optionally, part of the flat portion56fof the electrically conductive ring member56may be extended and used in place of the terminal portion Kt of the electrically conductive member K1. In that case, the electrically conductive member K1may be omitted.

According to the embodiment described above, electrical or thermal information about the electrically conductive members J housed in the interconnections can be gotten through the testing hole portions Ch cut through the plate. In this case, a metallic probe may be inserted into any of the testing hole portions Ch and the tip end of the probe may be brought into contact with one of the electrically conductive members J. Alternatively, a portion of the electrically conductive member J may stick out of the plate as shown inFIG. 11Band that portion sticking out of the plate may be probed.

For example, by measuring the potentials at the electrically conductive members J1and J2, the potential difference between the first and second electrodes E1and E2of the tubular thermoelectric generator T2can be obtained (seeFIGS. 18A and 18B). Likewise, by measuring the potentials at the electrically conductive members K1and J1, the potential difference between the first and second electrodes E1and E2of the tubular thermoelectric generator T1can be obtained. In this manner, the potential difference between the first and second electrodes E1and E2of each tubular thermoelectric generator T can be obtained. That is why even if some failure has occurred accidentally in any of the tubular thermoelectric generators T while the thermoelectric generator unit100is operating, it is easy to determine what tubular thermoelectric generator T has caused the failure.

In the embodiments described above, a channel C is formed by respective recesses cut in the first and second plate portions. However, the channel C may also be formed by a recess which has been cut in one of the first and second plate portions. If the container30is made of a metallic material, the inside of the channel C may be coated with an insulator to prevent the electrically conductive members (i.e., the connection plates and the terminal plates) from becoming electrically conductive with the container30. For example, the plate34(consisting of the plate portions34aand34b) may be comprised of a body made of a metallic material and an insulating coating which covers the surface of the body at least partially. Likewise, the plate36(consisting of the plate portions36aand36b) may also be comprised of a body made of a metallic material and an insulating coating which covers the surface of the body at least partially. If the respective surfaces of the recesses cut in the first and second plate portions are coated with an insulator, the insulating coating can be omitted from the surface of the electrically conductive member.

<Another Exemplary Structure to Establish Sealing and Electrical Connection>

FIGS. 25A and 25Bare cross-sectional views illustrating another exemplary structure for separating the hot and cold media from each other and establishing electrical connection between the tubular thermoelectric generators and the electrically conductive members.

In the example illustrated inFIG. 25A, a bushing60is inserted from outside of the container30, thereby separating the hot and cold media from each other and electrically connecting the tubular thermoelectric generator and the electrically conductive member together. In the example illustrated inFIG. 25A, the opening A42(seeFIG. 21) cut through the plate34uhas an internal thread portion Th34. More specifically, the wall surface of the recess R34that has been cut with respect to the opening A42of the plate34uhas the thread. The busing60with an external thread portion Th60is inserted into the recess R34. The bushing60has a through hole60athat runs in the axial direction. In this case, the end of the tubular thermoelectric generator T2has been inserted into the opening A42of the plate34u. That is why when the busing60is inserted into the recess R34, the through hole60acommunicates with the internal flow path of the tubular thermoelectric generator T2.

Inside the space left between the recess R34and the busing60, arranged are various members to establish sealing and electrical connection. In the example shown inFIG. 25A, a first O-ring52a, a washer54, the electrically conductive ring member56, the electrically conductive member J2, another washer54and a second O-ring52bare arranged in this order from the seating surface Bsa of the plate34utoward the outside of the container30. The end of the tubular thermoelectric generator T2is inserted into the respective holes of these members. The first O-ring52acontacts with the seating surface Bsa of the plate34uand the outer peripheral surface at the end of the tubular thermoelectric generator T2. In this case, when the external thread portion Th60is inserted into the internal thread portion Th34, the external thread portion Th60presses the first O-ring52aagainst the seating surface Bsa via the flat portion56fof the electrically conductive ring member56and the electrically conductive member J2. As a result, sealing can be established so as to prevent the fluid supplied into the shell32and the fluid supplied into the internal flow path of the tubular thermoelectric generator T2from mixing with each other. In addition, the second O-ring52bcontacts with the external thread portion Th60of the bushing60and the outer peripheral surface at the end of the tubular thermoelectric generator T2. In this case, the external thread portion Th60of the bushing60presses the second O-ring52bagainst the seating surface Bsa. As a result, sealing can be established so as to prevent the fluid outside of the plate34ufrom entering the inside of the channel C. Furthermore, since the outer peripheral surface of the tubular thermoelectric generator T2contacts with the elastic portions56rof the electrically conductive ring member56and since the flat portion56fof the electrically conductive ring member56contacts with the ring portion of the electrically conductive member J2, the tubular thermoelectric generator and the electrically conductive member can be electrically connected together.

On the other hand, in the example shown inFIG. 25B, a first O-ring52a, the electrically conductive member J2, the electrically conductive ring member56and a second O-ring52bare arranged in this order from the seating surface Bsa of the plate34utoward the outside of the container30. In addition, inFIG. 25B, another busing64with a through hole64ahas been inserted into the through hole60aof the busing60. The through hole64aalso communicates with the internal flow path of the tubular thermoelectric generator T2. In the example illustrated inFIG. 25B, the external thread portion Th64of the busing64presses the second O-ring52bagainst the seating surface Bsa.

Sealing from both of the fluids (the hot and cold media) can be established by arranging the first and second O-rings52aand52bin this manner. By establishing sealing from both of the fluids (the hot and cold media), corrosion of the electrically conductive ring member56can be minimized. Also, by using the busing, for example, as shown inFIGS. 25A and 25B, the hot and cold media can be separated from each other and the tubular thermoelectric generator and the electrically conductive member can be electrically connected together with an even simpler configuration. A washer54may be arranged between the O-ring and the electrically conductive member, for example.

<Thermoelectric Generator System Including the Thermoelectric Generator Unit>

Next, a thermoelectric generator system including the thermoelectric generator unit according to the present disclosure will be described.

The thermoelectric generator unit according to the present disclosure may be used by itself or a plurality of thermoelectric generator units may be used in combination. For example, if a thermoelectric generator system includes two thermoelectric generator units100, that thermoelectric generator system has a first a plurality of openings communicating with the respective flow paths of the multiple tubular thermoelectric generators T in the one thermoelectric generator unit100and a second plurality of openings communicating with the respective flow paths of the multiple tubular thermoelectric generators T in the other thermoelectric generator unit100. Naturally, two or more of the thermoelectric generator units100,100A and100B may be used in combination. Those thermoelectric generator units may be connected either in series to each other or parallel with each other.

Next, an exemplary configuration for a thermoelectric generator system including a plurality of thermoelectric generator units will be described with reference toFIGS. 26A, 26B and 26C. InFIGS. 26A, 26B and 26C, the bold solid arrows generally indicate the flow direction of the medium in contact with the outer peripheral surface of a tubular thermoelectric generator (i.e., the medium flowing inside of the container30(and outside of the tubular thermoelectric generator)). On the other hand, the bold dashed arrows generally indicate the flow direction of the medium in contact with the inner peripheral surface of a tubular thermoelectric generator (i.e., the medium flowing through the through hole (i.e., the inner flow path)). In the present specification, a path communicating with the fluid inlet and outlet ports of each container30will sometimes be referred to as a “first medium path” and a path encompassing the respective flow paths of the plurality of tubular thermoelectric generators will sometimes be referred to as a “second medium path” hereinbelow.

First of all, look atFIG. 26A. The thermoelectric generator system shown inFIG. 26Aincludes first and second thermoelectric generator units100-1and100-2, each of which may have the same configuration as the thermoelectric generator unit100described above. In the example illustrated inFIG. 26A, the space communicating with the fluid inlet and outlet ports of the container30of the first thermoelectric generator unit100-1and with the fluid inlet and outlet ports of the container30of the second thermoelectric generator unit100-2forms the first medium path. Also, in the example illustrated inFIG. 26A, an intervening plate35is provided to make the respective flow paths of the multiple tubular thermoelectric generators that the first thermoelectric generator unit100-1has communicate with their associated flow paths of the multiple tubular thermoelectric generators that the second thermoelectric generator unit100-2has. As a result, a second medium path, communicating with the respective flow paths of the tubular thermoelectric generators T of the first and second thermoelectric generator units100-1and100-2, is formed.

Next, look atFIG. 26B. As in the example shown inFIG. 26A, the thermoelectric generator system shown inFIG. 26Balso includes first and second thermoelectric generator units100-1and100-2. In the example shown inFIG. 26B, however, the respective flow paths of the multiple tubular thermoelectric generators that the first thermoelectric generator unit100-1has and their associated flow paths of the multiple tubular thermoelectric generators that the second thermoelectric generator unit100-2has communicate with each other via conduits42. The medium that has been supplied into the container30of the first thermoelectric generator unit100-1is supplied to the inside of the container30of the second thermoelectric generator unit100-2through another conduit40. It should be noted that these conduits40,42do not have to be straight ones but may be bent ones, too.

Next, look atFIG. 26C. The thermoelectric generator system shown inFIG. 26Cincludes first and second thermoelectric generator units100-1and100-2which are arranged parallel with each other. In the example illustrated inFIG. 26C, the medium flowing through the tubular thermoelectric generators of the first thermoelectric generator unit100-1and the medium flowing through the tubular thermoelectric generators of the second thermoelectric generator unit100-2run parallel to each other. However, the medium that has been supplied into the container30of the first thermoelectric generator unit100-1is also supplied into the container30of the second thermoelectric generator unit100-2.

As can be seen, in a thermoelectric generator system including a plurality of thermoelectric generator units, the flow paths of the hot and cold media may be designed in various manners.FIGS. 26A, 26B and 26Cillustrate just some examples of those various designs. And the first medium path communicating with the fluid inlet and outlet ports of respective containers and the second medium path encompassing the respective flow paths of the tubular thermoelectric generators may be designed arbitrarily. In the exemplary embodiments shown inFIGS. 26A, 26B and 26C, the second medium path is configured to make the fluid flow in the same direction through the respective flow paths of the multiple tubular thermoelectric generators T. However, the fluid does not have to flow in the same direction through the respective flow paths of the multiple tubular thermoelectric generators T. Rather the direction in which the fluid flows through the respective flow paths of those tubular thermoelectric generators T may be set in various manners according to the design of the flow paths of the hot and cold media.

In each of the thermoelectric generator units, wires W, each of which has its one end connected to an associated electrically conductive member, may be extended out of the plate through the testing hole portions Ch and aggregated together in a single terminal box. By getting a terminal box Tbx such as the ones shown inFIGS. 12A and 12Bshared by multiple thermoelectric generator units, electrical information about the respective electrically conductive members can be gotten more easily.

Next, an exemplary configuration for an electric circuit that the thermoelectric generator system may include will be described with reference toFIG. 27.

In the example shown inFIG. 27, the thermoelectric generator system200includes an electric circuit250which receives electric power from the thermoelectric generator unit (e.g., the thermoelectric generator unit100in this example). The electric circuit250includes a boost converter252which boosts the voltage of the electric power supplied from the thermoelectric generator unit100, and an inverter (DC-AC inverter)254which converts the DC power supplied from the boost converter252into AC power (of which the frequency may be 50/60 Hz, for example, but may also be any other frequency). The AC power may be supplied from the inverter254to a load400. The load400may be any of various electrical or electronic devices that operate using AC power. The load400may have a charging function in itself, and does not have to be fixed to the electric circuit250. Any AC power that has not been dissipated by the load400may be connected to a commercial grid410so that the electricity can be sold.

The electric circuit250in the example shown inFIG. 27includes a charge-discharge control section262and an accumulator264for storing the DC power obtained from the thermoelectric generator unit100. The accumulator264may be a chemical battery such as a lithium ion secondary battery, or a capacitor such as an electric double-layer capacitor, for example. The electric power stored in the accumulator264may be fed as needed to the boost converter252by the charge-discharge control section262, and may be used or sold as AC power via the inverter254.

The magnitude of the electric power supplied from the thermoelectric generator unit100may vary with time either periodically or irregularly. For example, if the heat source of the hot medium is the waste heat discharged from a factory, the temperature of the hot medium may vary according to the operating schedule of that factory. In that case, the power generation state of the thermoelectric generator unit100will vary so significantly that the voltage of the electric power supplied from the thermoelectric generator unit100and/or the amount of electric current will vary, too. However, even if the power generation state varies in this manner, the thermoelectric generator system200shown inFIG. 27can also minimize the influence caused by such a variation in power output level by making the charge-discharge control section262accumulate electric power in the accumulator264.

If the electric power generated is dissipated in real time, then the voltage step-up ratio of the boost converter252may be adjusted according to the variation in power generation state. Alternatively, a control operation may also be carried out so that the power generation state is maintained in steady state by regulating the flow rate, temperature and other parameters of the hot or cold medium to be supplied to the thermoelectric generator unit100with such a variation in power generation state sensed or predicted.

Now take a look atFIG. 4again. In the system illustrated inFIG. 4, the flow rate of the hot medium may be adjusted by the pump P1. In the same way, the flow rate of the cold medium may be adjusted by the pump P2. By adjusting the flow rate(s) of one or both of the hot and cold media, the power output level of the tubular thermoelectric generator can be controlled.

Optionally, the temperature of the hot medium may be controlled by adjusting the quantity of heat supplied from a high-temperature heat source (not shown) to the hot medium. In the same way, the temperature of the cold medium may also be controlled by adjusting the quantity of heat dissipated from the cold medium into a low-temperature heat source (not shown, either).

Although not shown inFIG. 4, the flow rates of the respective media supplied to the thermoelectric generator system may be adjusted by providing a valve and a branch path for at least one of the flow paths of the hot and cold media.

<Another Example of Thermoelectric Generator System>

Another example of a thermoelectric generator system including the thermoelectric generator unit will now be described with reference toFIG. 28.

A thermoelectric generator unit according to the present disclosure is applicable to a general waste disposal facility (that is a so-called “garbage disposal facility” or a “clean center”). In recent years, at a waste disposal facility, high-temperature, high-pressure steam (at a temperature of 400 to 500 degrees Celsius and at a pressure of several MPa) is sometimes generated from the thermal energy produced when garbage (waste) is incinerated. Such steam energy is converted into electricity by turbine generator and the electricity thus generated is used to operate the equipment in the facility.

The exemplary thermoelectric generator system300shown inFIG. 28includes at least one of the thermoelectric generator units described above. In the example illustrated inFIG. 28, the hot medium supplied to the thermoelectric generator unit (e.g., the thermoelectric generator unit100in this example) has been produced based on the heat of combustion generated at the waste disposal facility. More specifically, this system includes an incinerator310, a boiler320to produce high-temperature, high-pressure steam based on the heat of combustion generated by the incinerator310, and a turbine330which is driven by the high-temperature, high-pressure steam produced by the boiler320. The energy generated by the turbine330driven is given to a synchronous generator (not shown), which converts the energy into AC power (such as three-phase AC power).

The steam that has been used to drive the turbine330is turned back by a condenser360into liquid water, which is then supplied by a pump370to the boiler320. This water is a working medium that circulates through a “heat cycle” formed by the boiler320, turbine330and condenser360. Part of the heat given by the boiler320to the water does work to drive the turbine330and then is given by the condenser360to cooling water. In general, cooling water circulates between the condenser360and a cooling tower350.

As can be seen, only a part of the heat generated by the incinerator310is converted by the turbine330into electricity, and the thermal energy that the low-temperature, low-pressure steam has after the turbine330has been driven has not been converted into, and used as, electrical energy but often just dumped into the ambient according to conventional technologies. However, this thermoelectric generator unit100can use effectively the low-temperature steam or hot water that has done work to drive the turbine330as a heat source for the hot medium. In the example shown inFIG. 28, heat is obtained by the heat exchanger340from the steam at such a low temperature (of 140 degrees Celsius, for example) and hot water at 99 degrees Celsius is obtained, for example. And this hot water is supplied as hot medium to the thermoelectric generator unit100.

On the other hand, a part of the cooling water used at a waste disposal facility, for example, may be used as the cold medium. If the waste disposal facility has the cooling tower350, water at about 10 degrees Celsius can be obtained from the cooling tower350and used as the cold medium. Alternatively, the cold medium does not have to be obtained from a special cooling tower but may also be well water or river water inside the facility or in the neighborhood.

The thermoelectric generator unit100shown inFIG. 28may be connected to the electric circuit250shown inFIG. 27, for example. The electricity generated by the thermoelectric generator unit100may be either used in the facility or accumulated in the accumulator264. The extra electric power may be converted into AC power and then sold through the commercial grid410.

The thermoelectric generator system300shown inFIG. 28has a configuration in which thermoelectric generator units according to the present disclosure are incorporated into the waste heat utilization system of a waste disposal facility including the boiler320and the turbine330. However, to operate the thermoelectric generator units of the present disclosure, the boiler320, turbine330, condenser360and heat exchanger340are not indispensable members. If there is any gas or hot water at a relatively low temperature which has been just disposed of according to conventional technologies, that gas or water may be effectively used as hot medium directly. Or another gas or liquid may be heated by a heat exchanger and used as a hot medium. The system shown inFIG. 28is just one of many practical examples.

As is clear from the foregoing description of embodiments, a thermoelectric generator unit according to an embodiment of the present disclosure can electrically connect a plurality of tubular thermoelectric generators together with good stability using electrically conductive members housed in a channel on a plate. Such tubular thermoelectric generators are used in an environment in which the generators are in contact with a hot medium and a cold medium. That is why the electrical connection portions might cause electrical leakage or corrosion if these portions come into contact with these media. According to an embodiment of the present disclosure, however, the electrically conductive members can be arranged in a space in which sealing from the hot and cold media can be established relatively easily, and therefore, those tubular thermoelectric generators can be not only electrically connected together but also sealed easily.

In addition, according to an embodiment of the present disclosure, electrical or thermal information about the electrically conductive members can be retrieved out of the thermoelectric generator unit through the channel's testing hole portions. In this case, since the electrically conductive members housed in the channel are separated from the hot and cold media, the failures can be located without stopping the operation of the thermoelectric generator unit. As a result, practicality of thermoelectric generation increases.

As is clear from the foregoing description, an exemplary method of testing a thermoelectric generator unit according to the present disclosure includes the steps of: inserting a probe into a testing hole portion in the channel of the plate of the thermoelectric generator unit; bringing a tip end of the probe into contact with the electrically conductive member housed in the interconnection of the channel; and getting electrical or thermal information about the electrically conductive member with which the tip of the probe is in contact.

A thermoelectric generator unit as one implementation of the present disclosure comprises: a plurality of tubular thermoelectric generators, each of which has an outer peripheral surface, an inner peripheral surface and a flow path defined by the inner peripheral surface, and each of which generates electromotive force in an axial direction of each said tubular thermoelectric generator based on a difference in temperature between the inner and outer peripheral surfaces; a plurality of electrically conductive members providing electrical connection for the plurality of tubular thermoelectric generators; and a container housing the plurality of tubular thermoelectric generators inside, the container having fluid inlet and outlet ports through which a fluid flows inside the container, a plurality of openings into which the respective tubular thermoelectric generators are inserted, a shell surrounding the plurality of tubular thermoelectric generators, and a pair of plates, each of which is fixed to the shell and at least one of which has the plurality of openings and channels, each channel housing an electrically conductive member. In one embodiment, the respective ends of the tubular thermoelectric generators are inserted into the plurality of openings of the plates, at least one of the channels has an interconnection which connects at least two of the plurality of openings together and a testing hole portion which runs from the interconnection through an outer edge of the at least one plate, and the plurality of tubular thermoelectric generators are electrically connected together in series via the electrically conductive member that is housed in the interconnection of the at least one channel.

In one embodiment, two of the channels are terminal connections, each of which runs from one of the plurality of openings of the plate through an outer edge thereof.

In one embodiment, the plurality of electrically conductive members include: at least one connection plate with two through holes, into which two of the tubular thermoelectric generators are respectively inserted; and two terminal plates, each having a single through hole into which one of the tubular thermoelectric generators is inserted and having one end that sticks out, the at least one connection plate is housed in the interconnection of the at least one channel, the two terminal plates are respectively housed in the two terminal connections, a portion of each said terminal plate sticking out of the plate, and the at least one connection plate and the two terminal plates are electrically connected to the tubular thermoelectric generators inserted into the through holes.

In one embodiment, the at least one connection plate has a branch portion, and an end of the branch portion sticks out of the plate through the testing hole portion.

The thermoelectric generator unit may further comprises a wire, one end of which is electrically connected to the at least one connection plate and the other end of which is extended out of the plate through the testing hole portion.

The thermoelectric generator unit may further comprises a terminal box including a plurality of terminals. Each of the plurality of terminals may be electrically connected to an associated one of the electrically conductive members through the testing hole portion.

The thermoelectric generator unit may further comprises a terminal box which is arranged at the outer edge of one of the pair of plates and which includes a terminal. A portion of the wire extended out of the plate may be arranged along the outer edge of the plate, and the other end of the wire may be electrically connected to the terminal.

In one embodiment, the at least one connection plate has a threaded hole which has been cut parallel to the direction in which the testing hole portion runs.

In one embodiment, each of the plurality of openings has a first seating surface to receive a first O-ring inserted into the opening from outside of the shell, at least one of the pair of plates include: a first plate portion which is fixed to the shell and in which the first seating surface has been formed; and a second plate portion which is attached removably to the first plate portion, the plurality of openings running through the first and second plate portions, each of the plurality of openings of the second plate portion has a second seating surface to receive a second O-ring inserted into the opening, and in each channel, the electrically conductive member is arranged between the first and second O-rings.

In one embodiment, at least one of respective sealing surfaces of the first and second plate portions has a groove portion, the surface of which forms part of an inner peripheral surface of the testing hole portion.

In one embodiment, the at least one plate has an insulating coating which covers the inner peripheral surface of the testing hole portion of the at least one channel.

In one embodiment, the testing hole portion of the at least one channel runs straight from the interconnection through the outer edge of the plate.

In one embodiment, the testing hole portion of the at least one channel has a ramified portion inside of the plate.

In one embodiment, the at least one plate has a cap capable of closing the testing hole portion of the at least one channel.

Another implementation of the present disclosure is a method of testing the thermoelectric generator unit set forth above. The method comprises: inserting a probe into the testing hole portion of the at least one channel; bringing a tip end of the probe into contact with the electrically conductive member housed in the interconnection; and getting electrical or thermal information about the electrically conductive member with which the tip end is in contact.

A thermoelectric generator unit according to the present disclosure may be used as a power generator which utilizes the heat of an exhaust gas exhausted from a car or a factory, for example, or as a small-sized portable power generator.