Thermoelectric conversion module

Abstract

To provide a thermoelectric conversion module that uses a flexible substrate with good thermal conductivity and exhibits excellent thermoelectric cooling or heating effects. [Solution] A thermoelectric conversion module comprising: an anodized aluminum substrate having an anodized layer on one side of an aluminum plate and being flexible; a plurality of lower electrodes arranged on the side of the anodized aluminum substrate having the anodized layer; a thermoelectric conversion material arranged on the side of the lower electrodes opposite to the side with the anodized layer; and an upper electrode arranged on the side of the thermoelectric conversion material opposite to the lower electrode, wherein the thermoelectric conversion material is connected in series by the upper electrode and the lower electrode, the anodized aluminum substrate is fixed in contact with a heating element or heat sink, and both ends of the upper electrode of the thermoelectric conversion material connected in series have conductors that connect to a DC power supply that supplies current to the thermoelectric conversion element.

Description

Technical Field

[0001] The present disclosure relates to a thermoelectric conversion module.

Background Art

[0002] In recent years, attention has been focused on the utilization of renewable energy and clean energy in response to the issues of stable energy supply and the transition to a decarbonized society. Thermoelectric power generation, as one aspect of clean energy, has attracted attention. Thermoelectric power generation is a mechanism that converts the energy generated when heat moves from a high-temperature part to a low-temperature part into electrical energy for power generation. Therefore, it has the characteristic that clean power generation can be achieved for various applications according to the location where there is a temperature difference, such as natural heat sources (geothermal heat, ocean heat, human body heat, solar heat, etc.) and artificial heat sources (industrial waste heat, automobile waste heat, waste incinerator waste heat, etc.). In thermoelectric power generation, power generation is possible with a temperature difference of about several tens of K when actually generating electricity, and the range of heat source temperatures capable of power generation extends from -200°C to about 2000°C. Also, when generating electricity, since there are no mechanical moving parts, it is also an advantage that problems such as component wear and deterioration rarely occur.

[0003] As a conventional thermoelectric conversion module, a structure is known in which thermoelectric conversion materials are connected in series with metal electrodes and the outside is sandwiched between ceramic plates such as alumina plates. However, in known embodiments, the module needs to be installed on a flat heat source, and its applications are limited. As a material having flexibility, for example, using an organic resin substrate can be considered, but the resin substrate has a problem that its thermal conductivity is low and high-efficiency heat utilization cannot be expected. For example, the thermal conductivity of polyimide, which is a resin substrate, is 0.2 Wm

[0003] K -1 at 20°C, and the thermal conductivity is 237 Wm -1 K -1Compared to an aluminum plate, its thermal resistance is about 1 / 1000th, resulting in high thermal resistance. This means that the temperature difference generated by the thermoelectric conversion material cannot be transferred to the object being cooled or heated, making efficient use of thermoelectric conversion impossible. A thermoelectric conversion module has been proposed that is flexible and can be used in vehicle exhaust pipes, comprising a graphite sheet with an insulating layer formed on it, a substrate having a specific coefficient of thermal expansion, two spaced-apart lower electrodes formed on the surface of the insulating layer of the substrate, an n-type thermoelectric conversion layer and a p-type thermoelectric conversion layer formed on the surfaces of the two lower electrodes, and an upper electrode connecting these thermoelectric conversion layers, preferably having a flexible upper electrode (see Patent Document 1). In the thermoelectric conversion module described in Patent Document 1, the heat from a heat-generating element or heat-sinking element is used to generate electricity through the Seebeck effect. On the other hand, attempts have also been made to cool or heat a material by creating a temperature difference across its ends using an electric current, based on the principle of the Peltier effect.

[0004] Regarding cooling, for example, the depletion of the ozone layer is a problem due to the widespread use of fluorocarbons (CFCs) as refrigerants, making CFC-free operation an urgent necessity. While various CFC substitutes have been developed, effective reductions in environmental impact have not been achieved. Therefore, thermoelectric conversion modules, which are more compact than conventional refrigerators and have no moving parts, are highly desirable because their operation has a significantly lower environmental impact compared to conventional products. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-225346 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Graphite sheets are known to have high thermal conductivity under certain conditions. However, the thermoelectric conversion module described in Patent Document 1 has problems such as limitations on installation locations due to the flexibility of the upper electrode, and difficulties in selecting and manufacturing materials for the flexible upper electrode.

[0007] One embodiment of this disclosure aims to solve the problem of providing a thermoelectric conversion module that uses a flexible substrate with good thermal conductivity and exhibits excellent thermoelectric cooling or thermoelectric heating effects. [Means for solving the problem]

[0008] The following embodiments are included as specific means for solving the above problems. <1> An anodized aluminum substrate having an anodized layer on one side of an aluminum plate and being flexible, A plurality of lower electrodes are arranged on the side of the anodized aluminum substrate that has the anodized layer. A thermoelectric conversion material is disposed on the side of the lower electrode opposite to the anodic oxide layer, and The thermoelectric conversion material is provided with an upper electrode positioned on the opposite side from the lower electrode, The thermoelectric conversion material is connected in series by an upper electrode and a lower electrode. The anodized aluminum substrate is fixed in contact with the object to be cooled or heated. A thermoelectric conversion module having wires connected to a DC power supply that supplies current to the thermoelectric conversion elements at both ends of the upper electrodes of the series-connected thermoelectric conversion elements. <2> The thermoelectric conversion material includes a p-type thermoelectric conversion material and an n-type thermoelectric conversion material. <1> The thermoelectric conversion module described above. <3> The lower electrode is one or more selected from an indium layer, an indium-containing alloy layer, and a laminate having indium layers on both sides of a copper film. <1> or <2> The thermoelectric conversion module described above.

[0009] <4> The thermoelectric conversion module according to any one of <1> to <3>, wherein the lower electrode and the thermoelectric conversion material are joined via solder. <5> The thermoelectric conversion module according to any one of <1> to <4>, wherein the total thickness of the anodic aluminum oxide substrate is 0.3 mm to 1.0 mm, and the thickness of the anodic oxide layer is 15 μm to 30 μm. <6> The thermoelectric conversion module according to any one of <1> to <5>, wherein the surface of the anodic aluminum oxide substrate opposite to the side having the anodic oxide layer is used in contact with a curved cooling object or heating object. <7> The thermoelectric conversion module according to any one of <1> to <6>, wherein the thermoelectric conversion materials are connected in series in a direction perpendicular to the bending direction of the curved heat generating body via the upper electrode.

Advantages of the Invention

[0010] According to an embodiment of the present disclosure, there is provided a thermoelectric conversion module that uses a flexible substrate with good thermal conductivity and has an excellent thermoelectric cooling effect or thermoelectric heating effect.

Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 is a partial schematic view showing an embodiment of a thermoelectric conversion material portion in the thermoelectric conversion module of the present disclosure. [Figure 2] FIG. 2 is a partial schematic view showing an embodiment of one thermoelectric conversion element which is a laminate including a lower electrode, a thermoelectric conversion material, and an upper electrode in the thermoelectric conversion module of the present disclosure. [Figure 3] FIG. 3 is a partial schematic view showing an embodiment of an anodic aluminum oxide substrate in the thermoelectric conversion module of the present disclosure. [Figure 4] FIG. 4 is a schematic perspective view showing an embodiment of the thermoelectric conversion module of the present disclosure. [Figure 5A] FIG. 5A is a schematic plan view of the thermoelectric conversion module shown in FIG. 4. [Figure 5B]FIG. 5B is a model diagram showing an embodiment of a cylindrical heating or heat radiating body to which the thermoelectric conversion module shown in FIG. 5 is attached. [Figure 6] FIG. 6 is a graph showing the relationship between the change in the temperature of the high-temperature side electrode after current application and the applied current in the thermoelectric conversion module of Example 1 and the thermoelectric conversion module of Comparative Example 1. [Figure 7] FIG. 7 is a graph showing the relationship between the maximum temperature difference between the initial temperature of the supplied warm water and the temperature on the thermoelectric conversion module side, and the average temperature on the thermoelectric conversion module side in the thermoelectric conversion module of Example 1, the thermoelectric conversion module of Example 2, and the thermoelectric conversion module of Comparative Example 1.

Mode for Carrying Out the Invention

[0012] Hereinafter, the thermoelectric conversion module of the present disclosure will be described in detail. The description of the requirements described below may be based on typical embodiments of the present disclosure, but the present disclosure is not limited to such embodiments, and modifications can be appropriately made and implemented within the scope of the object of the present disclosure.

[0013] The "thermoelectric conversion module" according to the present disclosure refers to a module that can cool or heat an object using a thermoelectric conversion function by applying an electric current to the module. In the present disclosure, the numerical range indicated by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, "room temperature" refers to the ambient temperature in an uncontrolled state, which is usually in the range of 20°C to 35°C, and "room temperature" in experimental conditions refers to 25°C unless otherwise specified. In this disclosure, unless otherwise specified, the thickness of each layer is a value measured using a micrometer. In this disclosure, "flexibility" of an anodized aluminum substrate refers to the property of having the ability to bend the anodized aluminum substrate so that the anodized layer and the aluminum plate do not separate even when the anodized aluminum substrate is bent to a radius of curvature of 5 mm by stress.

[0014] In this disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. Components indicated by the same reference numeral in each drawing are considered to be the same component. Explanations for redundant components and reference numerals in each drawing may be omitted. The dimensional ratios in drawings do not necessarily represent the ratios of actual dimensions.

[0015] [Thermoelectric Conversion Module] The thermoelectric conversion module of the present disclosure (hereinafter also referred to as "the module of the present disclosure") comprises a flexible anodized aluminum substrate having an anodized layer on one side of an aluminum plate, a plurality of lower electrodes disposed on the side of the anodized aluminum substrate having the anodized layer, a thermoelectric conversion material disposed on the side of the lower electrodes opposite to the side with the anodized layer, and an upper electrode disposed on the side of the thermoelectric conversion material opposite to the lower electrode, wherein the thermoelectric conversion material is connected in series by the upper electrode and the lower electrode, the anodized aluminum substrate is fixed in contact with an object to be cooled or heated, and the upper electrodes of the series-connected thermoelectric conversion elements have conductors at both ends connected to a DC power supply that supplies current to the thermoelectric conversion elements. In the following, the laminate comprising the lower electrode, thermoelectric element, and upper electrode may be referred to as the thermoelectric element in the above configuration.

[0016] Figure 1 shows a partial schematic diagram of one embodiment of module 10 of this disclosure. Module 10 has a flexible aluminum plate 12, and the aluminum plate 12 has an anodized layer 14 on one side that functions as an insulating layer. A lower electrode (also called a mounting electrode) 16 is placed on one side of the anodized layer 14, and a p-type thermoelectric conversion material 18 and an n-type thermoelectric conversion material 20 are provided on the surface of the lower electrode 16. Figure 1 shows an embodiment having two laminates, each having a p-type thermoelectric conversion material 18 and an n-type thermoelectric conversion material 20 on the lower electrode 16. The p-type thermoelectric conversion material 18 and the n-type thermoelectric conversion material 20 provided on the adjacent lower electrode 16 are electrically connected by an upper electrode (also called a connecting electrode) 22 to form a thermoelectric conversion element 24 as a laminate. Figure 2 is a schematic partial diagram showing one embodiment of a thermoelectric element 24, which is a laminate comprising a lower electrode 16, a p-type thermoelectric material 18, an n-type thermoelectric material 20, and an upper electrode 22. This laminate is also called a Π-shaped element. Multiple of these laminates 24 are connected in series via the upper electrode 22 to constitute a thermoelectric module 10.

[0017] When an electric current is applied to a thermoelectric element, heat is transferred due to the Peltier effect, and each thermoelectric element essentially becomes a tiny heat pump.

[0018] The amount of heat transferred by the Peltier effect is proportional to the amount of current applied. The relationship between heat and current is expressed by the following equation. Formula:Q=πI In the equation, Q represents the amount of heat, I represents the amount of electric current, and π is the Peltier coefficient. Since changing the direction of electric current also reverses the junction surfaces where heat absorption and heat generation occur, the Peltier effect can be used to heat or cool any object.

[0019] The module of this disclosure comprises multiple p-type thermoelectric materials and n-type thermoelectric materials connected in series, for example, by upper and lower electrodes. By connecting the thermoelectric elements in series with electrodes, the amount of heat transferred is added up and becomes larger, allowing the module of this disclosure to heat or cool a target surface. What distinguishes it from a general heater is that it can not only heat but also cool. According to the module of this disclosure, by connecting multiple thermoelectric conversion elements in combination, the cooling or heating performance of an object is added up and increased by the applied current.

[0020] The following describes the constituent elements of each module of this disclosure.

[0021] (Anodized aluminum substrate) As shown in Figure 1, the anodized aluminum substrate 12 in the module of this disclosure has an anodized layer 14 on one side of an aluminum plate 12A. The anodic oxide layer can be formed by performing anodic oxidation on an aluminum plate, which is a metal substrate. Anodizing can be performed on an aluminum plate by using an oxalic acid aqueous solution, a phosphoric acid aqueous solution, or the like as an electrolyte, and applying a voltage of 40V to 70V for 10 to 90 minutes while maintaining the bath temperature at 25°C to 40°C.

[0022] From the viewpoint of achieving both flexibility and insulation, the total thickness of the anodized aluminum substrate (i.e., the total thickness of the aluminum plate and the anodized layer) is preferably in the range of 0.3 mm to 1.0 mm, and the thickness of the anodized layer on the aluminum substrate is preferably 15 μm to 30 μm. More preferably, the total thickness of the anodized aluminum substrate is in the range of 0.5 mm to 0.8 mm, the thickness of the anodized layer is more preferably 16 μm to 25 μm, and even more preferably 16 μm to 22 μm.

[0023] The anodic oxide layer is a layer formed directly on the aluminum plate and is an aggregate of porous layers. Figure 3 shows a schematic diagram of the anodic oxide layer 14 formed on the aluminum plate 12A. As shown in the schematic diagram, the anodic oxide layer 14, when viewed from the surface (the side opposite to the side in contact with the aluminum plate), is an aggregate of hexagonal film cells 28, each having a micropore 26 in the center. The size of the formed film cells and the size of the micropore in the center can be appropriately controlled by the electrolysis conditions.

[0024] From the viewpoint of maintaining the insulating properties of the aluminum substrate in this disclosure, it is preferable that the diameter of the film cell 28 is in the range of 100 nm to 300 nm, the diameter of the micropore 26 is in the range of 10 nm to 20 nm, and the height of the film cell 28, i.e., the thickness of the anodic oxide layer 14, is 16 μm to 22 μm. The micropores 26 formed in the center of the film cell 28 do not penetrate the film cell 28, and there is a gap between the bottom surface of the micropores 26 and the aluminum plate 12. It is believed that the anodic oxide coating portion between the micropores 26 formed in the film cell 28 that constitutes the anodic oxide layer 14 and the aluminum plate 12A contributes to ensuring insulation.

[0025] According to the inventors' research, it has been confirmed that an anodic oxidation layer of approximately 16 μm can be formed by using a 0.3 M oxalic acid aqueous solution as the anodic oxidation conditions, with a bath temperature of 30°C and an applied voltage of 50 V, and performing anodic oxidation on aluminum for 25 minutes. From the perspective of achieving a better balance between flexibility and insulation in an anodized coating, using a 0.3M oxalic acid aqueous solution, an anodized layer that maintains insulation properties can be formed by performing anodizing for 25 to 60 minutes. When using a 0.3M phosphoric acid aqueous solution, an anodized layer that maintains insulating properties is formed by performing anodizing for approximately 12 times longer than when using a 0.3M oxalic acid aqueous solution.

[0026] When focusing on the thickness of the anodized layer, from the viewpoint of exhibiting good flexibility, when the thickness of the anodized layer derived from the oxalic acid aqueous solution is in the range of 15 μm to 20 μm, cracks due to bending stress are unlikely to occur even when placed on a curved surface with a radius of curvature of 5 mm to 16 mm. Furthermore, at a radius of curvature of 30 mm, some cracks occur, but it has been confirmed that delamination between the anodized layer and the aluminum plate does not occur, and the insulating properties are not impaired. In the case of anodized films derived from an aqueous phosphoric acid solution, using a 0.3M aqueous phosphoric acid solution, an anodized film of 1μm to 2μm thickness is formed after 60 minutes of anodizing treatment. Even when placed on a curved surface with a radius of curvature of 5mm, cracks due to bending stress are unlikely to occur. Furthermore, at radii of curvature of 10mm to 30mm, some cracks may occur, but it has been confirmed that delamination between the anodized layer and the aluminum plate does not occur, and the insulating properties are not impaired.

[0027] The flexibility of the aluminum substrate under bending stress will be evaluated under the following conditions. The evaluation equipment used includes the AUTOGRAPH AG-I (Shimadzu Corporation), the ECLIPSE L200N optical microscope (Nikon Corporation), and the JCM-6000PLUS scanning electron microscope (JEOL Ltd.), and the evaluation was performed under conditions of curvature radii of 5 mm to 20 mm. The evaluation method involves observing the surface morphology after the three-point bending test and checking for delamination between the bent anodic oxide film (anodic oxide layer) and the aluminum plate using an optical microscope, scanning electron microscope, etc. Five samples were evaluated, and the median value was used as the evaluation result.

[0028] (Lower electrode) The module of this disclosure comprises a plurality of lower electrodes (mounted electrodes) on the side of the aluminum substrate that has an anodized layer. A soft material, such as a soft metal like indium, is preferred as the lower electrode. Alternatively, a thin metal electrode having a resistance value similar to that of indium may be used. In particular, from the viewpoint of having flexibility that can follow the flexibility of the aluminum substrate, it is preferable that the lower electrode be one or more selected from an indium layer, an indium-containing alloy layer, and a laminate having indium layers on both sides of a copper layer. The indium layer is soft and conforms well to the shape of the anodized layer formed on the aluminum plate, even when the module of this disclosure is placed on a curved surface. It is also resistant to peeling and possesses the necessary conductivity. The lower electrode can be provided on the surface of the anodic oxide layer by soldering. There are no particular restrictions on the method of forming the lower electrode. For example, it can be formed using a general-purpose soldering iron by depositing a gold thin film onto an anodized aluminum support. Alternatively, the lower electrode can be formed without a gold deposition film by using an ultrasonic soldering iron. The thickness of the lower electrode is not particularly limited as long as it has sufficient conductivity, but from the viewpoint of flexibility, it can be 0.2 mm to 0.5 mm thick, and 0.3 mm to 0.4 mm is preferred. Furthermore, the size (size in plan view) of the lower electrode formed on the anodized aluminum substrate can be appropriately selected according to the installation location of the module, its intended use, and the required electromotive force. For example, in one embodiment where the module is applied to a heat dissipation pipe with a curvature of 10 mm, the lower electrode can be 3 mm to 5 mm in width and 7 mm to 9 mm in length.

[0029] In the module of this disclosure, a thermoelectric conversion material is provided on the surface of the lower electrode opposite to the side in contact with the anodic oxide layer. Thermoelectric materials are generally elements that generate an electromotive force by joining two different metals or semiconductors to create a temperature difference across their ends. From the viewpoint of obtaining a larger potential difference, it is preferable that the thermoelectric material includes both a p-type thermoelectric material and an n-type thermoelectric material. Since the thermoelectric conversion material is a pair of thermoelectric conversion elements including a p-type thermoelectric conversion material and an n-type thermoelectric conversion material, the current applied to the module of this disclosure can be efficiently converted into heat, and the object can be heated or cooled depending on the direction of the current. As the p-type thermoelectric conversion material and n-type thermoelectric conversion material, known p-type semiconductors and n-type semiconductors can be used. The materials constituting the thermoelectric conversion material are appropriately selected depending on the temperature applied to the module. For example, bismuth-tellurium systems (Bi-Te systems, e.g., Bi2Te3) may be selected from room temperature to 500K (227°C), lead-tellurium systems (Pb-Te systems) from 500K to 800K (527°C), and silicon-germanium systems (Si-Ge systems) from 800K to 1000K (727°C).

[0030] p-type and n-type thermoelectric materials are formed by coating the lower electrode material onto an anodized aluminum substrate and then arranging it while heating. More specifically, one method involves applying indium, which can also act as a soldering agent, onto an anodized aluminum substrate and then bonding it using an ultrasonic soldering device (for example, the Sunbonder ultrasonic soldering device manufactured by Komuratec Co., Ltd.). One method involves applying indium to the surface of the p-type thermoelectric conversion material and the n-type thermoelectric conversion material on the anodized aluminum substrate side, bonding them together using an ultrasonic soldering device, and then heating them to bond the indium layer formed on the anodized aluminum substrate to the indium layer formed on the p-type thermoelectric conversion material and the n-type thermoelectric conversion material. According to the above method, the bottom portions of the p-type thermoelectric conversion material and the n-type thermoelectric conversion material are arranged so as to be embedded in the lower electrode. Therefore, the preferred thickness of the lower electrode of 0.2 mm to 0.5 mm mentioned earlier is the thickness of the region without the p-type thermoelectric conversion element and the n-type thermoelectric conversion element, and the thickness of the lower electrode in the portion where the p-type thermoelectric conversion element and the n-type thermoelectric conversion element are embedded is approximately 0.02 mm to 0.05 mm. Even at this thickness, the conductivity of the lower electrode is not impaired, and it is considered that stable fixation between the p-type thermoelectric conversion material and the lower electrode of the n-type thermoelectric conversion material is achieved.

[0031] There are no particular restrictions on the size of the p-type and n-type thermoelectric materials. The size of the p-type and n-type thermoelectric conversion materials is determined appropriately by the area ratio based on the thermal conductivity and electrical resistivity of each material. If the materials have similar thermal conductivity and electrical resistivity, a rectangular prism-shaped material with dimensions of 1mm to 3mm in width, 1mm to 3mm in length, and 2mm to 5mm in height is generally preferred. If the radius of curvature of the heat source is small, it is preferable to reduce the above values, i.e., to use a smaller size.

[0032] (Top electrode) The module of this disclosure includes an upper electrode. By connecting a thermoelectric conversion element, which is mounted on the surface of the lower electrode, with the upper electrode, the amount of heat absorbed or released can be increased according to the purpose. There are no particular limitations on the configuration of the upper electrode; any conductive material can be used without restriction. Examples of upper electrodes include copper foil and aluminum foil. From the viewpoint of heat dissipation and reduction of electrical loss, copper foil with a thickness of about 0.5 mm is preferably used for the upper electrode. The size of the upper electrode is not particularly limited as long as it is large enough to connect adjacent thermoelectric conversion materials, but from the viewpoint of preventing short circuits, the width can be set to about 3 mm to 4 mm and the length to about 6.5 mm to 7.5 mm to match the thermoelectric conversion material.

[0033] The module of this disclosure has a plurality of laminates on one side of an anodized aluminum substrate, each laminate comprising a thermoelectric conversion material and an upper electrode described later on the lower electrode surface, i.e., a plurality of thermoelectric conversion elements. The thermoelectric conversion materials in the plurality of thermoelectric conversion elements are connected to adjacent thermoelectric conversion elements in the laminate by the upper electrodes described later, thereby increasing the cooling or heating effect of each individual thermoelectric conversion element additively. In the module of this disclosure, when current is applied from a conductor connected to both terminal ends of the upper electrode, one of the individual thermoelectric elements is cooled and the other is heated due to the Peltier effect. By bringing the cooled surface or heated surface of the thermoelectric element, which has a lower electrode, a thermoelectric material, and an upper electrode, into contact with the object to be cooled or heated via an anodized aluminum substrate with good thermal conductivity, the object can be cooled or heated.

[0034] Since the module of this disclosure uses a flexible anodized aluminum substrate, when the side of the anodized aluminum substrate opposite to the side having the anodized layer is used in contact with an object to be cooled or heated, it can conform to the shape of the curved object to be cooled or heated, and the object can be cooled or heated efficiently.

[0035] When the module of this disclosure comes into contact with a curved object to be cooled or heated, it is preferable that the thermoelectric conversion elements are connected in series by the upper electrode in a direction perpendicular to the curvature direction of the curved object to be cooled or heated, from the viewpoint of achieving better shape conformity to the curved surface.

[0036] By connecting the thermoelectric elements in the module of this disclosure in series with the upper electrode, the cooling or heating performance is added together and becomes larger. Therefore, by applying current to the module of this disclosure through the conductors provided at both ends of the upper electrode, the object can be efficiently cooled or heated even with a small current supply. On the other hand, the module of this disclosure may also have the thermoelectric conversion elements connected in parallel. Therefore, the circuit should be determined in such a way that a cooling or heating effect suitable for the application of the module of this disclosure can be obtained.

[0037] (conductor) The module of this disclosure comprises conductors for supplying current to both ends of the upper electrodes of connected thermoelectric materials. The conductors can be selected and used from known types as appropriate. The conductors are provided at both ends of a plurality of thermoelectric materials connected in series or parallel, and the current supplied to the module of this disclosure cools or heats the target object.

[0038] Figure 4 is a schematic perspective view showing one embodiment of the module 10 of this disclosure, which is formed by connecting a plurality of thermoelectric materials in series. As shown in Figure 4, the module 10 of this disclosure has a lower electrode 16, a p-type thermoelectric material 18, and an n-type thermoelectric material 18 on an anodized aluminum substrate made of an aluminum plate 12 on which an anodized layer 14 is formed. Adjacent p-type thermoelectric material 18 and n-type thermoelectric material 20 are connected in series by an upper electrode 22, and both ends of the upper electrode connected in series are provided with conductors 30 for supplying current to the thermoelectric materials. A DC power supply 32 is connected to the conductors 30 to supply current to the module of this disclosure. In the DC power supply connection method shown in Figure 4, the upper electrode side is cooled and the lower electrode side is heated.

[0039] Figure 5A is a schematic plan view of the thermoelectric conversion module shown in Figure 4. The thermoelectric conversion module 10 shown in Figure 4 is connected in series via the lower electrode 16 and the upper electrode 22, as shown in the schematic plan view in Figure 5A. In a preferred embodiment, the thermoelectric conversion module 10 is configured such that a thermoelectric conversion material (not shown) is connected in series via a lower electrode 16 and an upper electrode 22 in a direction perpendicular to the curvature of a curved object to be cooled or heated. Figure 5A shows a configuration in which the DC power supply 32 is connected in the opposite direction to that shown in Figure 4. In the configuration shown in Figure 5A, the direction of the DC current flow is the opposite to that shown in Figure 4, so the lower electrode side is cooled and the upper electrode side is heated. Therefore, in the thermoelectric conversion module of this disclosure, the direction of cooling or heating can be controlled by controlling the connection direction of the DC current. Figure 5B is a model diagram showing one embodiment of a cylindrical object to be cooled or heated to which the thermoelectric conversion module 10 shown in Figure 5A is to be attached. The module 10 shown in Figure 4 can be attached to the curved surface of a cylindrical object to be cooled or heated to which the module 10 is to be cooled or heated to which the module 10 is to be attached to the curved surface of the cylindrical object to be cooled or heated to which the module 10 is to be heated to, in the direction indicated by the arrow in Figure 5B. Since the lower electrode 16 is in close proximity to the object to be cooled or heated 34 and in close contact with the aluminum oxide substrate 12, even if it is connected parallel to the curvature direction, it is less affected by the curved surface compared to the upper electrode 22. Furthermore, as described above, in one embodiment, the lower electrode 16 contains a soft metal such as indium, which improves the conformability of the lower electrode to the curved surface. On the other hand, the upper electrode 22 is located at a distance from the object to be cooled or heated 34 and is susceptible to the effects of curved surfaces. Therefore, it is preferable that it be connected in series in a direction perpendicular to the curvature direction. In Figure 5B, the thermoelectric conversion material is mainly connected in series via the upper electrode 22 in a direction perpendicular to the curvature direction of the curved object to be cooled or heated 34. This arrangement reduces the influence of curved surfaces on the performance of the module 10.

[0040] The module disclosed herein can be installed on curved surfaces, offering a high degree of flexibility in installation location. Furthermore, precise temperature control is possible by controlling the amount of current supplied. The module of this disclosure does not require any moving parts, is more compact than conventional refrigerators or heaters, and has a lower environmental impact during operation compared to conventional products. Therefore, one embodiment of its use is installation near faucets in residential facilities, such as washrooms and bathrooms. Generally, there is a distance from the water heater to the faucet, and there is a time lag before the hot water coming out of the faucet reaches the desired temperature. By installing the module of this disclosure near the faucet, it is possible to supply hot water at the required temperature instantaneously from the moment the hot water is turned on, thereby shortening the time it takes for the hot water to reach the desired temperature. The module of this disclosure significantly reduces the time it takes for the supplied hot water to reach the appropriate temperature. Furthermore, the same control can be applied not only to hot water but also to chilled water supplied from a cooler using the module of this disclosure. Furthermore, in another embodiment of its use, in manufacturing sites for industrial products, food products, etc., simply by attaching the module of this disclosure to existing equipment such as pipes, it becomes easier to handle fluids that require precise temperature control. Therefore, the module of this disclosure has a low environmental impact, enables temperature control with minimal power consumption, and, in particular, can perform cooling without requiring a refrigerant, thus having a wide range of applications. [Examples]

[0041] The manufacturing method of this disclosure will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing procedures, etc., shown in the following examples can be modified as appropriate without departing from the spirit of this disclosure. Therefore, the thermoelectric conversion module relating to this disclosure should not be interpreted restrictively by the specific examples shown below. Unless otherwise specified, the percentages "%" below refer to mass.

[0042] The module related to this disclosure will be explained in more detail below.

[0043] <Example 1> [Fabrication of anodized aluminum substrates] An anodized aluminum substrate was obtained by anodic oxidation of one side of a 99.99% pure aluminum plate (thickness: 0.5 mm, size: 25 mm x 25 mm) using a 0.3 M oxalic acid aqueous solution as the electrolyte, with an electrode distance of 20 mm, a bath temperature of 30°C, and an applied voltage of 50 V, over a period of 25 minutes, forming an anodized layer of approximately 16 μm.

[0044] [Evaluation of the flexibility of anodized aluminum substrates] The obtained anodized aluminum substrates were evaluated using an AUTOGRAPH AG-I (Shimadzu Corporation) under conditions of curvature radius from 5 mm to 30 mm. As part of the evaluation, the surface morphology after the three-point bending test and the presence or absence of delamination between the bent anodized film (anodic oxide layer) and the aluminum plate were observed using an optical microscope ECLIPSE L200N (Nikon Corporation) and a scanning electron microscope JCM-6000PLUS (JEOL Ltd.). Three samples were evaluated for each method.

[0045] As a result, no cracks occurred at a radius of curvature of 30 mm, but cracks did occur at radii of curvature between 5 mm and 16 mm. However, no delamination of the anodic oxide layer was observed under any of the conditions.

[0046] The insulating properties of the anodized aluminum substrate were evaluated by placing aluminum electrodes between the anodized and unanodized surfaces of an aluminum plate and measuring the voltage V-current I characteristics using an ultra-high resistance / micro-current meter 8340A (ADC Corporation). As a result, the obtained anodized aluminum substrates exhibited insulating properties under all anodizing conditions.

[0047] [Formation of the lower electrode and thermoelectric conversion element] On the anodized layer side of the obtained anodized aluminum substrate, indium was applied as the lower electrode material in an amount that resulted in a film thickness of 0.3 mm, using an ultrasonic soldering iron, in accordance with the shape of the lower electrode (size: 5 mm x 11 mm). A p-type thermoelectric conversion material and an n-type thermoelectric conversion material were placed on the coated surface while being heated to approximately 200°C. When the thermoelectric conversion material was placed on the lower electrode material, it penetrated into the lower electrode layer at the placement location, and the thickness of the lower electrode in the region containing the thermoelectric conversion material was measured with a micrometer and found to be 0.032 mm. Two rows of lower electrodes and thermoelectric conversion elements were formed in the width direction and one row in the length direction on an anodized aluminum substrate.

[0048] [Formation of the upper electrode] The two thermoelectric materials formed as described above were joined in series using an upper electrode. The upper electrode was made of copper foil with a thickness of 0.1 mm and a size of 6 mm x 10 mm coated with indium. The thermoelectric elements were connected in series by connecting a p-type thermoelectric material and an n-type thermoelectric material formed on different lower electrodes of adjacent thermoelectric materials.

[0049] [Wire connection] By connecting wires to both ends of the upper electrodes of the thermoelectric conversion elements connected in series, and then connecting the wires to a DC power supply, the thermoelectric conversion module of Example 1 was obtained.

[0050] <Example 2> The module of Example 2 was obtained in the same manner as in Example 1, except that the lower electrode in Example 1, which was a single-layer indium layer obtained by coating an anodized aluminum substrate with indium, was replaced with a multi-layer lower electrode having indium layers on both sides of a copper foil (copper layer). The method for forming the lower electrode is shown below. [Formation of the lower electrode] An indium layer was applied to an anodized aluminum substrate, a copper foil (0.1 mm thick) was placed on the surface, and then indium was applied to the copper foil surface to form a lower electrode with a multilayer structure of indium layer / copper layer / indium layer.

[0051] <Comparative Example 1> A thermoelectric conversion module having two thermoelectric conversion elements was obtained in the same manner as in Example 1, except that a 0.5 mm thick alumina substrate (aluminum oxide substrate) was used instead of the anodized aluminum substrate of Example 1. Because alumina is hard and inflexible, when the module of Comparative Example 1 was attached to a pipe, which was a heat source with a radius of curvature of 20 mm, the contact area between the substrate and the pipe was narrow.

[0052] [Evaluation of thermoelectric conversion modules] <Rating 1> The thermoelectric conversion module of Example 1 was attached to a pipe with a radius of curvature of 20 mm, and the conductors of the thermoelectric conversion module were connected to an external DC power supply (DC stabilized power supply: GP060-20R, Takasago Manufacturing Co., Ltd.). The applied current was varied in the range of 2A to 8A. The temperature of the hot water flowing through the pipe was kept constant at 20°C, and an electric current was applied. The relationship between the difference between the upper electrode temperature and the lower electrode temperature after the current was measured. The results are shown in Figure 6. As shown in Figure 6, it can be seen that increasing the applied current increases the temperature difference between the lower and upper electrodes of the module.

[0053] <Rating 2> The thermoelectric conversion modules of Example 1, Example 2, and Comparative Example 1 were mounted on a pipe with a radius of curvature of 20 mm, and the conductors of the thermoelectric conversion modules were connected to an external DC power supply (DC stabilized power supply: GP060-20R, Takasago Manufacturing Co., Ltd.). Figure 7 shows the relationship between the temperature on the lower side and the maximum temperature difference, calculated by changing the temperature of the cooling water supplied to the pipe, measuring the relationship between current and temperature difference near the optimal current value for each module, and determining the maximum temperature difference. The measurement involved installing each thermoelectric conversion module on the curved surface of a pipe with a radius of curvature of 20 mm. The relationship between the average temperature of the heat-dissipating electrode (lower electrode) and the temperature difference between the two electrodes, i.e., the temperature difference between the upper and lower electrodes, was measured and the relationship between the two was shown. The results are shown in Figure 7.

[0054] According to Figure 7, in the modules of Example 1 and Example 2, the maximum temperature difference (ΔT) is within the range of the average temperature on the heat dissipation side from 20°C to 80°C. max While temperatures of 100°C or higher were achieved, in the module of Comparative Example 1, as mentioned above, the maximum temperature difference remained at 50°C to 60°C due to the small contact area between the module and the pipe. [Explanation of Symbols]

[0055] 10 Thermoelectric Conversion Modules 12 Anodized aluminum substrate 12A Aluminum Plate 14. Anodized layer 16 Lower electrode 18 p-type thermoelectric materials 20 n-type thermoelectric materials 22 Upper electrode 24 Thermoelectric conversion elements 26 Micropore 28 coated cells 30 conductor 32 DC power supply 34 Objects to be cooled or heated

Claims

1. An anodized aluminum substrate having an anodized layer on one side of an aluminum plate and being flexible, A plurality of lower electrodes are arranged on the side of the anodized aluminum substrate that has the anodized layer. A thermoelectric conversion material is disposed on the side of the lower electrode opposite to the anodic oxide layer, and The thermoelectric conversion material is provided with an upper electrode positioned on the opposite side from the lower electrode, The thermoelectric conversion material is connected in series by an upper electrode and a lower electrode. The anodized aluminum substrate is fixed in contact with the object to be cooled or heated. A thermoelectric conversion module having conductors connected to a DC power supply that supplies current to the thermoelectric conversion elements at both ends of the upper electrodes of the series-connected thermoelectric conversion elements.

2. The thermoelectric conversion module according to claim 1, wherein the thermoelectric conversion material includes a p-type thermoelectric conversion material and an n-type thermoelectric conversion material.

3. The thermoelectric conversion module according to claim 1, wherein the lower electrode is one or more selected from an indium layer, an indium-containing alloy layer, and a laminate having indium layers on both sides of a copper film.

4. The thermoelectric conversion module according to claim 1, wherein the lower electrode and the thermoelectric conversion material are joined via solder.

5. The thermoelectric conversion module according to claim 1, wherein the total thickness of the anodized aluminum substrate is 0.3 mm to 1.0 mm, and the thickness of the anodized layer is 15 μm to 30 μm.

6. The thermoelectric conversion module according to claim 1, wherein the side of the anodized aluminum substrate opposite to the side having the anodized layer is used in contact with a curved object to be cooled or heated.

7. The thermoelectric conversion module according to claim 1, wherein the thermoelectric conversion material is connected in series via the upper electrode in a direction perpendicular to the curvature direction of the curved object to be cooled or heated.

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