JP2010278191A - Thermoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric conversion element which has a large-area heat exchange structure that is produced by a simple method, and has high efficiency of thermoelectric conversion and durability. <P>SOLUTION: In the thermoelectric conversion element including a pair of electrode substrates 11 and 12 disposed opposing each other, a thermoelectric conversion module for which a plurality of thermoelectric semiconductors are electrically connected to the opposing inner surface side of the electrode substrates, and a fin for heat exchange on the outer surface side of at least one of the pair of electrode substrates, the fin for the heat exchange is a spiral heat exchange fin 16. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermoelectric conversion element using the Seebeck effect.

  The performance of a power generating element using a thermoelectric semiconductor is greatly affected by the thermal contact state between the high temperature side serving as a heat source and the low temperature side serving as a cooling source. For example, when the high temperature side heat source is not flat but uneven, a technique is known in which a heat exchange structure between the element and the high temperature side heat source is important (see, for example, Patent Documents 1 and 2). In Patent Document 1, in order to improve the thermal contact state, a material enclosing a cushioning material containing a metal having a low melting point is arranged between the heat source and the element to improve heat transfer efficiency, but a relatively large convex When there is a point, the nearby cushioning agent cannot contact the heat source and has a problem that the heat conduction efficiency is lowered. Further, in Patent Document 2, although the heat transfer efficiency through the fluid is improved by using the hollow fins, the heat exchange efficiency by the hollow fins greatly decreases unless the fluid continues to flow. Then there is a problem to say. Further, the efficiency of heat exchange is greatly influenced by the direction of the fluid, and there is a problem that the function as a fin can hardly be achieved depending on the direction. On the other hand, a spiral structure has been proposed as a so-called heat sink (see, for example, Patent Document 3). However, there has been no suggestion of a heat exchange structure with a large area that is durable and inexpensive and can be applied to a power generation element by thermoelectric conversion. Further, in the above technique, when the adhesion to the heat source having unevenness is increased, internal stress is likely to be generated in the element, and it cannot be said that the element is excellent in durability against a heating / cooling cycle or the like.

JP 2006-24608 A JP 2008-78587 A JP 2004-311711 A

  The present invention has been made in view of the above problems, and an object thereof is to provide a thermoelectric conversion element having a large area heat exchange structure that can be manufactured by a simple method and having high thermoelectric conversion efficiency and durability. .

  The above object of the present invention is achieved by the following means.

  1. A pair of electrode substrates disposed opposite to each other, a thermoelectric conversion module in which a plurality of thermoelectric semiconductors are electrically connected to opposite inner surfaces of the electrode substrate, and at least one of the pair of electrode substrates A thermoelectric conversion element having heat exchange fins on the outer surface side thereof, wherein the heat exchange fins are helical heat exchange fins.

  2. 2. The thermoelectric conversion element according to 1, wherein the spiral heat exchange fins are arranged so as to be parallel to each other.

  3. Said 1 or 2 thermoelectric conversion element characterized by the said helical heat exchange fin consisting of metal foil.

  4). 4. The thermoelectric conversion element according to any one of 1 to 3, wherein the spiral heat exchange fins are disposed on both of the electrode substrates.

  5. 5. The thermoelectric conversion element according to any one of 1 to 4, wherein a ratio of a length to a diameter of the helical heat exchange fin is 2 or more.

  According to the present invention, a heat exchange structure having a large area can be produced in a thermoelectric conversion element by a simple method, high thermoelectric conversion capability is obtained, and durability is excellent.

It is a schematic sectional drawing which shows an example of a structure of the thermoelectric conversion element which concerns on this invention. It is a schematic diagram which shows arrangement | positioning of the helical conductive member in the high temperature side and low temperature side of the thermoelectric conversion element of this invention.

  The thermoelectric conversion element of the present invention includes a pair of electrode substrates arranged opposite to each other, a thermoelectric conversion module in which a plurality of thermoelectric semiconductors are electrically connected to the inner surface of the electrode substrate facing each other, and an outer surface of the electrode substrate. It has a helical heat exchange fin.

[Helical heat exchange fins]
The helical heat exchange fin according to the present invention refers to a structure obtained by winding one (sheet) or a plurality of elongated materials so that the cross-sectional size and shape are substantially the same for each pitch. In addition, the spiral shape can be regarded as a pseudo-pipe. In the present invention, when the spiral shape is regarded as a pipe, the outer diameter is measured so that the diameter of the spiral heat exchange fin is the largest value. Is defined as the length of the helical heat exchange fin. Such a structure has several features.

  (I) Stretchable: Helical heat exchange fins can stretch in the height direction when the spiral is regarded as a cylinder. At this time, the stress applied to the inside of the member can be reduced as compared with a simple columnar or prismatic structure. Similarly, it has elasticity in the direction perpendicular to the cross section of the helix. Further, no stress is originally applied to a direction perpendicular to both the cross section and the length direction.

  In addition, the helical heat exchange fin is excellent in flexibility and flexibility, and can follow a curved surface such as a pipe or an uneven surface, and can have high thermal conductivity. In particular, when conventional heat exchange fins such as corrugated fins are used as heat absorption fins and adaptation to curved surfaces such as pipes is attempted, the fins interfere with each other, and the efficiency of heat exchange may be significantly reduced. Spiral heat exchange fins have a spatial space called pitch, so that they can maintain high heat exchange without interfering with spiral heat exchange fins when bent in any direction. I can do it.

  (Ii) Heat conduction is uniform: When a spiral heat exchange fin is used, a fluid serving as a heat source (cooling source) is allowed to flow through the heat exchange fin, or a solid heat source (cooling source) is used for heat exchange. It is also possible to exchange heat by bringing fins into contact.

  In particular, when the spiral heat exchange fin according to the present invention is used in contact with a solid heat source while being laid down, the spiral heat exchange fin contacts the heat source at a point or a surface. Therefore, since the distance (heat conduction path) between the support substrate and the heat source via the spiral heat exchange fins is uniform, efficient heat conduction can be performed.

  Further, when the heat source has irregularities, if there is a pitch (line interval) sufficiently larger than the size of the projections, the projections can be escaped and the uniformity of heat conduction can be maintained. In addition, even if the convex contacts the helical heat exchange fin, the helical heat exchange fin has high elasticity, so that it can flexibly cope with uneven surfaces. Further, since each pitch of the helix is not physically affected, the left and right pitches of the pitches with which the projections are in contact are not affected and deformed.

  When using helical heat exchange fins as heat dissipation fins, the surface area can be increased, and heat dissipation is excellent, so even if the cooling medium does not continue to flow (even if air is not sent by a fan, etc.) ) Efficient heat dissipation is possible. Further, since the heat dissipation performance is not affected by the flow direction of the cooling medium such as wind, it can be installed in various places without considering the place and direction of installing the thermoelectric conversion element.

  (Iii) High productivity: It is a member that can be easily produced continuously, and can be produced in large quantities at low cost.

  The helical heat exchange fin in the present invention has a length / diameter ratio of 2 or more, preferably 20 or more, and more preferably 100 or more. Thereby, the heat exchange efficiency is improved, the conversion efficiency is increased, and the durability is also improved. Conversely, in the following cases, both conversion efficiency and durability deteriorate. Here, when the winding method of the spiral heat exchange fin is not an accurate circle, the major axis may be regarded as the diameter.

  The preferred diameter of the heat exchange fin is determined according to need. However, if the outer diameter is small, it is not preferable because the heat exchange ability cannot be sufficiently obtained. On the other hand, if it is too large, the use of the element will be hindered. In addition, an appropriate value exists because it is not preferable in terms of cost. In this element, the minimum value of a preferable outer diameter is 0.1 mm or more. More preferably, it is 0.5 mm or more. Further, the maximum value of the outer diameter is preferably 10 times or less, more preferably 5 times or less, with respect to the thickness of the element body not including the heat exchange fins.

  The helical heat exchange fin in the present invention may be a so-called coil spring having a cross section of a generatrix or a square shape, or a member obtained by winding a thin wire around a core wire. It can be used. Among these, a so-called foil wire obtained by winding a metal foil having a thin wire cross section around a substantially elliptical shape or a substantially rectangular shape around a core wire is preferable. The length / diameter ratio according to the present invention is preferably 2 or more, more preferably 5 or more. In many cases, the length / diameter ratio of a coil spring is about several tens of times. The length / diameter ratio in the case of a coil spring is 2-50, preferably 5-30. On the other hand, in the present invention, a member produced to have a length of several kilometers with a diameter of about several tens to several hundreds of μm, such as a foil wire, that is, a member having a length / diameter ratio of 100,000 or more Alternatively, it is also preferable to use it after cutting it to an appropriate length. When such a member is used, when a heat exchange structure having high followability to a surface having irregularities is efficiently provided in a large area, such a linear shape is formed on a thin and long electrode along the longitudinal direction. Since a large number of the members can be arranged in parallel and at the same time, it is possible to produce a heat exchange structure that extends in the same shape as the substantially planar heat exchange space at low cost.

  By winding the thin wire or metal foil in a single layer, the helical heat exchange fin according to the present invention can be obtained. Further, a spiral heat exchange fin obtained by winding a double or more multilayer, especially a metal foil in multiple layers is also preferable. In the case of a helical heat exchange fin obtained by winding around a core wire, it can be used with the core wire remaining inside, but it can also be used with the core wire removed. A method of dissolving and removing the core wire with a solvent that can dissolve the core wire and a method of removing the core wire by firing are applicable.

  In the helical heat exchange fin according to the present invention, the member having a length / diameter ratio of 2 or more is preferably made of a material having a thermal conductivity of 2 W / (m · K) or more. Resin composites with various metals such as copper, aluminum and silver, ceramics such as alumina, aluminum nitride, silicon carbide and zirconia, and high heat transfer fillers as materials having thermal conductivity of 2W / (m · K) or more It is preferable to use carbon materials such as carbon fibers and carbon nanotubes. Of course, a material obtained by combining these materials and a material that has been subjected to surface treatment to improve heat radiation ability can also be used. The thermal conductivity of these helical heat exchange fins is preferably 10 W / (m · K) or more, more preferably 50 W / (m · K) or more.

  As a method for producing a spiral shape, the above-described general method for producing a coil spring can be applied, and a method for producing a copper foil yarn wire, for example, copper foil yarn wire production described in Japanese Published Utility Model Publication Sho 62-7113 The law etc. can be used. In the case of ceramic, a method of putting a ceramic precursor into a mold and firing, and a method described in JP-A-2005-340484 can be used if a metal is disposed in the ceramic coil.

  As a material having a thermal conductivity of 2 W / (m · K) or more, it is preferable to use a spring-like member having a high elastic deformability, but it is also preferable to use a member that easily causes plastic deformation. In particular, when it is important that the deformability capable of following local irregularities is high, it is preferable to use a material having a low elastic modulus or a metal material having a wide so-called plastic deformation region.

  The surface of the base material of the helical heat exchange fin may be smooth or may have fine irregularities. Depending on the required performance, it can be selected along with the material type.

[Selection of thermoelectric semiconductor]
As the type of thermoelectric semiconductor constituting the thermoelectric conversion element, a bismuth-tellurium-based semiconductor, a Si-Ge-based semiconductor, a Pb-Te-based semiconductor, or the like is applicable. In addition, there are filled skutterudite compounds, boron compounds, zinc antimony, clathrates, pseudogap-based Heusler compounds, various oxides, and the like. Details include, for example, “High-efficiency and high-reliability technology for thermoelectric conversion systems” (2006, Technical Information Association), “Thermoelectric Conversion Technology Handbook” (2008, NTS Corporation), etc. Can be helpful. Organic thermoelectric semiconductors can also be used. From these, an appropriate semiconductor can be selected according to the temperature range to be used and the required electric energy.

[Structure of thermoelectric conversion element]
Regarding the arrangement of the electrodes and thermoelectric semiconductors sandwiched between the substrates, the description in the book can be referred to. For example, refer to the descriptions in “Thermoelectric Conversion System High Efficiency and High Reliability Technology” (2006, Technical Information Association), “Thermoelectric Conversion Technology Handbook” (2008, NTS Corporation), etc. Can be.

  Furthermore, the structure of the thermoelectric change element of this invention is demonstrated using figures. In addition, the thermoelectric conversion element shown in the following figures shows an example of the thermoelectric change element of this invention, and this invention is not limited only to the structure illustrated here.

  FIG. 1 is a schematic cross-sectional view showing an example of the configuration of the thermoelectric conversion element of the present invention.

  In the thermoelectric conversion element 1 shown in FIG. 1A, a pair of a p-type thermoelectric semiconductor 14 and an n-type thermoelectric semiconductor 15 is sandwiched between electrode substrates 11 and 12, respectively. There is a bonding space 13 made of solder or the like. The joint space 13 may have stress relaxation ability, and preferably exists on both sides of the thermoelectric semiconductors 14 and 15 as shown in FIG.

  As the electrode substrate, it is possible to prepare a copper plate, an aluminum plate, or the like, which is a conductive metal, as the electrode substrate, and directly provide heat exchange fins on the outer surface. When using a plurality of elements connected in series, the electrode substrate may be partially cut away to ensure electrical insulation between the electrodes.

  A method of separately preparing an electrically insulating substrate and combining it with an electrode substrate can also be applied. That is, on the outside of the electrode substrate, an electrically insulating substrate such as a stainless steel plate with an insulating film can be used so as to keep the element form, protect the inside and prevent the heat exchange from the outside. By producing an electrode substrate having electrical conductivity on the inner surface later, the portion can be used as an electrode substrate.

  As a method of manufacturing the electrode substrate later, a method of directly forming a conductive material on the surface of the insulating substrate in a layered manner by plating, spraying, or the like, copper foil, aluminum foil or the like having an appropriate size Alternatively, a method of pasting a material having a thickness can be used. By performing patterning at the same time when these electrode substrates are manufactured, it is possible to eliminate the insulation treatment between the elements.

  The helical heat exchange fins 16 and 16 'in the present invention are arranged on the outside so that the helical axis is parallel to the electrode surface (the orientation with respect to the p and n pairs is schematically shown). Not limited to this). As shown in the three-dimensional view of FIG. 1B, it is also preferable that the helical heat exchange fins are arranged in parallel planes.

  FIG. 2 is a schematic view showing the arrangement of the spiral conductive members on the high temperature side and the low temperature side of the thermoelectric conversion element of the present invention.

  Spiral heat exchange fins have voids, and when the thermoelectric conversion element comes into contact with a heat source or cooling source having a wall-like outer wall surface, it exerts stress relaxation capability and at the same time enhances thermal adhesion. To do. The helical heat exchange fin has a structure in which only individual contact portions are deformed with respect to local unevenness and adjacent contact portions are not easily deformed, and therefore has high followability with respect to minute unevenness. When the unevenness is large, it can be easily followed by using a member having a helical outer diameter corresponding to the unevenness. Furthermore, in this case, direct heat transfer through the spiral heat exchange fins is often more effective than heat transfer by fluid convection. Therefore, the heat source and cooling of the base material of the spiral heat exchange fins are effective. It is preferable that the contact area with the source is increased by contact in a line (or plane) shape, for example, a shape like a foil wire.

  On the other hand, when the cooling source is air, so-called air cooling, the helical heat exchange fins are in contact with other members and do not need to be deformed. Since air cooling is cooling through contact with air or heat exchange by convection, it is preferably a heat exchange part having a structure capable of efficiently contacting a large area. For this reason, as described above, it is preferable to use a spiral heat exchange fin after processing to increase the specific surface area of the member constituting the helix. For example, a metal base material is preferably a wire provided with irregularities sandwiched between opposing gears or a spiral heat exchange fin provided with minute irregularities by etching. The cross section of the helical heat exchange fin is large enough not to impede productivity, and preferably has a shape that enters the air layer. The bonding shape with the substrate does not need to be linear as described above, and may be any shape that does not hinder heat exchange inside and outside the spiral heat exchange fin of the fluid by convection. This applies not only to air cooling but also to liquids such as water cooling. When the heat source is a high-temperature fluid and the spiral structure on the surface of the element is in direct contact, it is desirable to take a structure that has a large cross-section and greatly enters the fluid, similar to the air cooling described above.

  In the present invention, it is only necessary to have a helical heat exchange fin on either the heat source side or the cooling source side. However, in order to improve the thermoelectric conversion efficiency, it is preferably provided at least on the heat source side, and further on both sides. It is preferable to provide in. In particular, in order to produce a heat exchange structure with high conversion efficiency and high durability, not only the long axes of the spiral heat exchange fins on one side are parallel to each other. It is preferable that the major axes of the members on both sides of the heat source and the cooling source are also parallel to each other. As a result, even when the thermoelectric conversion element is pasted on a curved surface, it is easy to improve the adhesion of the element and achieve high efficiency, and also the stress relaxation ability can be increased, and the durability of the heat exchange part can be increased. .

  Spiral heat exchange fins can be directly bonded to an electrically insulating substrate, bonded to an insulating substrate via an intermediate bonding member, or directly to an electrode in an element without an insulating substrate. It is. In this case, it is necessary to join the electrodes so as not to short-circuit each other. For joining, a low melting point metal such as solder can be used, and various adhesives, welding, brazing and the like can be applied. In joining, if a larger amount of joining material is used than necessary, a large amount of materials are required for joining, which is disadvantageous in terms of cost, and at the same time, the above-mentioned adhesion and stress relaxation properties may be impaired. On the other hand, if the amount is too small, the heat conduction efficiency is lowered together with the bonding reliability, and sufficient heat exchange ability cannot be obtained, and the electromotive force is also impaired, so that an appropriate value exists. The value can be obtained experimentally. However, when it is considered that the helical heat exchange fin forms a planar space, it is 10% by volume or more and 90% by volume or less with respect to the total volume. preferable. More preferably, it is 20 volume% or more and 80 volume% or less.

[Method of arranging helical heat exchange fins]
The helical heat exchange fin according to the present invention can be manufactured by appropriately selecting the thickness distribution according to the required thickness of the support substrate and arranging the thickness distribution with an appropriate manufacturing apparatus. All conventionally known methods are applicable. When the spiral heat exchange fins are arranged in parallel, the adjacent spiral heat exchange fins may be in contact or in close contact with each other, but with respect to the space formed by the spiral heat exchange fins, It does not necessarily occupy a high density. When used as a heat exchange member for air cooling, it is possible to increase the air convection and increase the cooling capacity by having a slight gap. A slight gap also works advantageously in the adhesion to the curved surface. However, if voids are present locally when the helical heat exchange fins are arranged, heat exchange capability can be obtained locally, but it cannot be expected to improve the function of the entire device. Therefore, it is preferable that the voids are small and uniformly distributed in the heat exchange space. For example, when observed in the thickness direction from the projection surface of the planar heat exchange space, it is desirable that the gap where no conductive material exists is apparently small. Preferably it is 30% or more, more preferably 70% or more.

  From the above viewpoint, it is preferable that the long axis of the helical conductive member is arranged in parallel. As a result, the air gaps can be disposed more uniformly in the heat exchange space, and at the same time, the flexibility in at least a certain direction can be improved and the durability can be improved.

  In order to arrange the spiral conductive members in parallel, for example, the following methods and combinations thereof are conceivable.

  (1) A helical heat exchange fin is temporarily fixed in parallel and then joined to a substrate or the like.

  (2) A spiral heat exchange fin is sequentially joined to a substrate or the like.

  In the case of (1) above, when a copper foil wire is used as the helical heat exchange fin, it can be easily arranged and fixed by using a V-groove substrate for optical fibers, etc. After temporarily forming the foil wire into a ribbon shape with an adhesive or the like, the binder is removed only on the joint surface, and cream solder or silver paste is applied. After bonding to the substrate through a reflow furnace, the binder and the core wire of the foil wire are removed using a solvent, whereby the bonding of the spiral heat exchange fin and the substrate can be completed. Instead of temporary molding, it is also possible to perform soldering and joining to the electrodes coated with cream solder in a state where foil wires are arranged in parallel and attached to a tape-like holding member.

  In the case of (2) above, when a metal is used as the helical heat exchange fin, it has a function as a coil, and so-called high-frequency heating is possible. Therefore, a small amount of bonding metal such as solder is contained in the core wire, and after adhering to the electrode, when the metal for bonding in the core wire is melted by high frequency heating, it exudes from its own weight and spiral heat exchange fin, It can be expected to be joined to the electrode. Using this method, a heat exchange space in which a spiral conductive member is arranged can be produced by repeating the heating and joining one by one on the substrate. In addition to this, various heat bonding methods such as resistance heating can be applied.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Preparation and surface treatment of p and n thermoelectric semiconductors A p-type thermoelectric semiconductor ((Bi ₂ Te ₃ ) _0.25 (Sb ₂ Te ₃ ) ₀ having a thickness of about 500 μm and a thickness of several mm square produced by a twin roll quenching method in argon. _.75 ) A Ni film having a thickness of 1 μm was formed on both sides of the thin _piece by an ion plating method.

Similarly, an n-type thermoelectric semiconductor ((Bi ₂ Te ₃ ) _2.7 (Bi ₂ Se ₃ ) _0.3 ) having a thickness of about 500 μm and a rectangle of several mm square produced by a twin roll method is provided on both sides of a thin piece. Ni films each having a thickness of 1 μm were formed by ion plating.

  Both were surface-treated semiconductor pieces having minute irregularities of 0.1 mm or less on the surface and having the same variation in thickness.

Production of thermoelectric conversion element 1 [Production of helical heat exchange fin]
1) Coil spring: Cu-Be wire with a thickness of 0.1 mm and a wound length of 0.5 mm and a winding pitch of 0.12 mm are wound with a predetermined length. The coil spring 1 (copper wire spiral heat exchange fin) was obtained.

  A coil spring 2 and a coil spring 3 having a winding outer diameter of 0.75 mm and 1 mm in the same manner as the production of the coil spring 1 were respectively used (the winding pitch was 0.12 mm).

  2) Foil wire spiral heat exchange fin: a core wire made of twisted 0.08mm thick tetron wire, wound with copper foil of width 0.22mm and thickness 0.023mm, and wound outer diameter ( What was wound at a diameter of 0.19 mm and a winding pitch of 0.12 mm was cut to a predetermined length to obtain a foil wire spiral heat exchange fin 1.

  The foil wire spiral heat exchange fins 1 and foil wire spiral heat exchange fins 2 and 0.40 mm and 0.60 mm, respectively, were prepared in the same manner as the production of the foil wire spiral heat exchange fins 1. The replacement fin 3 was used (the winding pitch was 0.12 mm).

  Zirconia coil spring: The coil spring 1 produced in the above 1) was cast with plaster to produce the coil spring 1. Next, an aqueous dispersion (containing 90% by mass of zirconia) of zirconia powder (average particle size 10 μm) to which a dispersant and an antifoaming agent were added was injected into the mold of the coil spring 1 and allowed to stand and dried. Then, it was temporarily fired at 1000 degrees and fired in a vacuum furnace at 1600 degrees for 3 hours. After sufficiently cooling, the zirconia coil spring taken out from the gypsum was washed and dried to obtain a zirconia coil spring.

  Polyester coil spring: The coil spring 1 produced in the above 1) was molded with plaster to produce a mold of the coil spring 1. A polyethylene terephthalate resin melted by heat in this mold was injected under pressure, and after sufficiently cooling, the polyester coil spring taken out from the gypsum mold was washed and dried to obtain a polyester coil spring.

[Production of Thermoelectric Conversion Element 1]
(1) Production of low-temperature side (air-cooled) substrate Thermoplastic silver paste (STAY STICK 191 manufactured by Techno Alpha Co., Ltd.) on one side of a stainless steel substrate (size 7 cm × 3 cm, thickness about 50 μm) having an alumina insulating film on the surface After coating and standing, the coil spring 1 (length / diameter ratio: 3) prepared in 1) above was individually supplied to the stainless steel substrate using a coil spring spring feeder. At this time, all the coil springs 1 were placed on the substrate in a lying state, and provided so that the projected area of the coil spring 1 was 40% of the stainless steel substrate area. Thereafter, the substrate was heated using an IR heater in a vacuum chamber depressurized to 1 Torr (1 Torr is 133.322 Pa) using an IR heater, and a coil spring was joined. On the back side, a stainless steel mask is attached to the center of the stainless steel substrate, and then a film-like aluminum electrode substrate (about 50 μm) is provided by gas flame spraying using an acetylene gas combustion flame (2800 ° C). A substrate was produced.

(2) Production of High-Temperature Side Substrate A high-temperature side substrate was produced by providing a film-like aluminum electrode substrate having a thickness of about 50 μm by gas flame spraying using a combustion flame of acetylene gas on a stainless steel substrate having an alumina insulating coating.

  A lead-free spherical cream solder having an average diameter of 30 to 40 μm was applied to the surface of the manufactured high temperature side substrate provided with a film-like aluminum electrode substrate using a metal mask (aperture ratio of about 0.57).

  Thereafter, p-type and n-type semiconductor pieces were placed on the cream solder using tweezers. Lead free spherical cream solder having an average diameter of 30 to 40 μm was also applied to the surface of the low temperature side substrate provided with the aluminum electrode film using a metal mask (aperture ratio of about 0.57). The low-temperature side electrode is placed on the p-type and n-type semiconductor piece arrangement surface of the high-temperature side substrate, and the semiconductor piece is fixed with a weight so as to sandwich the semiconductor piece. Then, the thermoelectric conversion element 1 was produced by sealing.

  For the sealing, an electrically insulating silicone sealant (Cemedine 8000) was used, and sealing was performed so that the aluminum sprayed electrodes protruded at both ends at a width of 1 cm. The sealant was hardened by drying until tack-free, and then reducing the pressure by inserting an injection needle so as to ensure the escape path of the gas inside, and then heating after the inside was almost evacuated.

[Production of thermoelectric conversion elements 2 to 21]
Thermoelectric conversion elements 2 to 21 were produced by the following method.

  A thermoelectric conversion element 2 was produced in the same manner as the thermoelectric conversion element 1 except that the coil spring 1 having a length / diameter ratio of 3 was randomly arranged on the low temperature side electrode.

  A thermoelectric conversion element 3 was produced in the same manner as the thermoelectric conversion element 1 except that the coil spring 1 having a length / diameter ratio of 10 was provided on the low temperature side electrode. The thermoelectric conversion element 3 does not have all the coil springs arranged in parallel, and has a coil spring that is fixed without being partially parallel.

  A thermoelectric conversion element 4 was produced in the same manner as the thermoelectric conversion element 1 except that the coil spring 1 having a length / diameter ratio of 30 was provided outside the low temperature side electrode substrate so that the coil springs were parallel to each other.

  A thermoelectric conversion element 5 was produced in the same manner as the thermoelectric conversion element 1 except that the coil spring 2 having a length / diameter ratio of 3 was provided outside the low temperature side electrode substrate so that the coil springs were parallel to each other.

  A thermoelectric conversion element 6 was produced in the same manner as the thermoelectric conversion element 1 except that the coil spring 2 having a length / diameter ratio of 10 was provided outside the low temperature side electrode substrate so that the coil springs were parallel to each other.

  A thermoelectric conversion element 7 was produced in the same manner as the thermoelectric conversion element 1 except that the coil spring 3 having a length / diameter ratio of 3 was provided outside the low temperature side electrode substrate so that the coil springs were parallel to each other.

  A thermoelectric conversion element 8 was produced in the same manner as the thermoelectric conversion element 1 except that the coil spring 3 having a length / diameter ratio of 10 was provided outside the low temperature side electrode substrate so that the coil springs were parallel to each other.

  A thermoelectric conversion element 9 was produced in the same manner as the thermoelectric conversion element 1 except that a zirconia coil spring having a length / diameter ratio of 3 was provided outside the low temperature side electrode substrate so that the coil springs were parallel to each other.

  A thermoelectric conversion element 10 was produced in the same manner as the thermoelectric conversion element 1 except that zirconia coil springs having a length / diameter ratio of 3 were randomly arranged outside the low temperature side electrode substrate.

  A thermoelectric conversion element 11 was produced in the same manner as the thermoelectric conversion element 1 except that a polyester coil spring having a length / diameter ratio of 3 was provided outside the low temperature side electrode substrate so that the coil springs were parallel to each other.

  A thermoelectric conversion element 12 was produced in the same manner as the thermoelectric conversion element 1 except that polyester coil springs having a length / diameter ratio of 3 were randomly arranged outside the low temperature side electrode substrate.

  The thermoelectric conversion element 1 except that the foil wire spiral heat exchange fin 1 having a length / diameter ratio of 50 is provided outside the low temperature side electrode substrate so that the foil wire spiral heat exchange fins are parallel to each other. The thermoelectric conversion element 13 was produced by the same method.

  The thermoelectric conversion element 1 except that the foil wire spiral heat exchange fin 1 having a length / diameter ratio of 100 is provided outside the low temperature side electrode substrate so that the foil wire spiral heat exchange fins are parallel to each other. The thermoelectric conversion element 14 was produced by the same method.

  The thermoelectric conversion element 1 except that the foil wire spiral heat exchange fin 1 having a length / diameter ratio of 150 is provided outside the low temperature side electrode substrate so that the foil wire spiral heat exchange fins are parallel to each other. The thermoelectric conversion element 15 was produced by the same method.

  The thermoelectric conversion element 1 except that the foil wire spiral heat exchange fin 2 having a length / diameter ratio of 100 is provided outside the low temperature side electrode substrate so that the foil wire spiral heat exchange fins are parallel to each other. The thermoelectric conversion element 16 was produced by the same method.

  The thermoelectric conversion element 1 except that the foil wire spiral heat exchange fin 2 having a length / diameter ratio of 150 is provided outside the low temperature side electrode substrate so that the foil wire spiral heat exchange fins are parallel to each other. The thermoelectric conversion element 17 was produced by the same method.

  The thermoelectric conversion element 1 except that the foil wire spiral heat exchange fin 3 having a length / diameter ratio of 100 is provided outside the low temperature side electrode substrate so that the foil wire spiral heat exchange fins are parallel to each other. The thermoelectric conversion element 18 was produced by the same method.

  The thermoelectric conversion element 1 except that the foil wire spiral heat exchange fin 3 having a length / diameter ratio of 150 is provided outside the low temperature side electrode substrate so that the foil wire spiral heat exchange fins are parallel to each other. The thermoelectric conversion element 19 was produced by the same method.

(Comparative example)
Except for providing a commercially available corrugated fin-type heat sink 1 having a height of 4.6 mm and a fin pitch of 2.1 mm so as to cover 40% of the stainless steel substrate area in the projected area ratio, the same method as the thermoelectric conversion element 1, The thermoelectric conversion element 20 was produced.

  With reference to the shape described in FIG. 2 of Japanese Patent Application Laid-Open No. 2008-78578, the corrugated fin heat sink 2 processed to have a height of 0.2 mm and a fin pitch of 0.5 mm so as to cover 40% of the area of the stainless steel substrate. A thermoelectric conversion element 21 was produced in the same manner as the thermoelectric conversion element 1 except that it was provided.

<Measurement of thermoelectric conversion efficiency>
Each obtained thermoelectric conversion element was placed so that the outside of the high temperature electrode substrate was in contact with a 120 ° C flat plate hot plate, and the outside of the low temperature electrode substrate was placed in a direction parallel to the main axis of the heat exchange fin with 20 ° C air. The electromotive force value obtained from the low temperature side electrode in a state of flowing at 3 m / s was measured, and the thermoelectric conversion efficiency was measured.

  The electromotive force value obtained from the low temperature side electrode was measured under the same conditions except that the air flowing outside the low temperature electrode substrate was flowed in a direction perpendicular to the main axis of the heat exchange fin, and the thermoelectric conversion efficiency was measured. .

  The thermoelectric conversion efficiency was determined as a relative value in the thermoelectric conversion element 1, with the electromotive force value when air was passed in the direction parallel to the main axis of the helical heat exchange fin as 100. The larger the relative power value obtained, the higher the thermoelectric conversion capability. Table 1 shows an electromotive force value of each thermoelectric conversion element.

<< Durability Evaluation >>
The stress relaxation ability of the heat exchange space was evaluated as follows.

  Each thermoelectric conversion element was allowed to stand in a freezer at −40 ° C. for 30 seconds and then left on a hot plate at 120 ° C. for 30 seconds, and the above-described thermoelectric conversion efficiency evaluation was performed. The cooling air was measured by flowing parallel to the cooling surface, and the value is shown as a relative value with the value of the thermoelectric conversion element 1 being 100.

  As is apparent from Table 1, the thermoelectric conversion element having the fins for heat exchange according to the present invention is superior in conversion efficiency because the cooling air is better than the thermoelectric conversion element provided with the corrugated fin heat sink. I understand that. In particular, a thermoelectric conversion element provided with a corrugated fin heat sink is extremely inefficient when the cooling air is perpendicular to the main axis of the fin, since the fin on the windward side blocks the cooling air. Furthermore, in the heat exchange elements 1 to 12 in which the coil spring is a heat exchange fin, when the cooling air is perpendicular to the main axis of the fin, the cooling air passes through the gap of the coil, so that it is almost in the direction of the cooling air. It turns out that it is not influenced.

[Production of Thermoelectric Conversion Elements 22 to 39]
The length / diameter outside the high temperature side electrode substrate is the same as the method where the helical heat exchange fins are not provided outside the low temperature side electrode substrate and the helical heat exchange fins are provided outside the low temperature side electrode substrate. A thermoelectric conversion element 22 was produced in the same manner as the thermoelectric conversion element 1 except that the coil spring 1 having a ratio of 10 was provided.

  A thermoelectric conversion element 23 was produced in the same manner as the thermoelectric conversion element 22 except that the foil wire spiral heat exchange fin 1 having a length / diameter ratio of 50 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 24 was produced in the same manner as the thermoelectric conversion element 22 except that the foil wire spiral heat exchange fin 1 having a length / diameter ratio of 100 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 25 was produced in the same manner as the thermoelectric conversion element 22 except that the foil wire spiral heat exchange fin 1 having a length / diameter ratio of 150 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 26 was produced in the same manner as the thermoelectric conversion element 22 except that the foil wire spiral heat exchange fin 2 having a length / diameter ratio of 100 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 27 was produced in the same manner as the thermoelectric conversion element 22 except that the foil wire spiral heat exchange fin 2 having a length / diameter ratio of 150 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 28 was produced in the same manner as the thermoelectric conversion element 22 except that the foil wire spiral heat exchange fin 3 having a length / diameter ratio of 100 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 29 was produced in the same manner as the thermoelectric conversion element 22 except that the foil wire spiral heat exchange fin 3 having a length / diameter ratio of 150 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 30 was produced in the same manner as the thermoelectric conversion element 22 except that the corrugated fin heat sink 1 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 31 was produced in the same manner as the thermoelectric conversion element 22 except that the corrugated fin heat sink 2 was provided outside the high temperature side electrode substrate.

  Thermoelectric conversion except that a coil spring 1 having a length / diameter ratio of 10 is provided outside the low temperature side electrode substrate and a foil wire spiral heat exchange fin 1 having a length / diameter ratio of 100 is provided outside the high temperature side electrode substrate. A thermoelectric conversion element 32 was produced by the same method as for the element 1.

  Thermoelectric conversion except that a coil spring 2 having a length / diameter ratio of 10 is provided outside the low temperature side electrode substrate, and a foil wire spiral heat exchange fin 1 having a length / diameter ratio of 150 is provided outside the high temperature side electrode substrate. A thermoelectric conversion element 33 was produced in the same manner as the element 32.

  The foil wire helical heat exchange fin 1 having a length / diameter ratio of 50 is provided outside the low temperature side electrode substrate, and the foil wire helical heat exchange fin having a length / diameter ratio of 100 outside the high temperature side electrode substrate. A thermoelectric conversion element 34 was produced in the same manner as the thermoelectric conversion element 32 except that 1 was provided.

  The foil wire helical heat exchange fin 1 having a length / diameter ratio of 100 is provided outside the low temperature side electrode substrate, and the foil wire helical heat exchange fin having a length / diameter ratio of 150 is provided outside the high temperature side electrode substrate. A thermoelectric conversion element 35 was produced in the same manner as the thermoelectric conversion element 32 except that 1 was provided.

  A foil wire spiral heat exchange fin 1 having a length / diameter ratio of 150 is provided outside the low temperature side electrode substrate, and a foil wire spiral heat exchange fin having a length / diameter ratio of 100 is provided outside the high temperature side electrode substrate. A thermoelectric conversion element 36 was produced in the same manner as the thermoelectric conversion element 32 except that 1 was provided.

  A foil wire helical heat exchange fin 2 having a length / diameter ratio of 100 is provided outside the low temperature side electrode substrate, and a foil wire helical heat exchange fin 1 having a length / diameter ratio of 150 is provided on the high temperature side electrode. A thermoelectric conversion element 37 was produced in the same manner as the thermoelectric conversion element 32 except that it was provided.

  A thermoelectric conversion element 38 was produced in the same manner as the thermoelectric conversion element 32 except that the corrugated fin type heat sink 1 was provided outside the low temperature side electrode substrate and the corrugated fin type heat sink 1 was provided outside the high temperature side electrode substrate.

  A thermoelectric conversion element 39 was produced in the same manner as the thermoelectric conversion element 32 except that the corrugated fin type heat sink 2 was provided outside the low temperature side electrode substrate and the corrugated fin type heat sink 2 was provided outside the high temperature side electrode substrate.

  In addition, in the thermoelectric conversion elements 32 to 39, the low-temperature electrode side substrate outer spiral heat exchange fin main axis and the high-temperature electrode side substrate outer spiral heat exchange fin main axis were provided in parallel.

<Measurement of thermoelectric conversion efficiency>
Each obtained thermoelectric conversion element is attached to a 500 mm diameter steel pipe whose surface is satin-finished so that the main axis of the pipe and the main axis of the heat exchanging fin are parallel to each other. The other surface was cooled while flowing air at 20 ° C. in a direction parallel to the main axis of the pipe at 3 m / s. In this state, the electromotive force value obtained from the low temperature side electrode was measured.

  The electromotive force was measured under the same conditions except that the thermoelectric conversion element was attached so that the main axis of the pipe and the main axis of the heat exchange fin were perpendicular to each other. The value of the electromotive force is obtained by calculating the relative value of the thermoelectric conversion element 22 when the thermoelectric conversion element 22 is attached so that the main axis of the pipe and the main axis of the spiral heat exchange fin are parallel to each other. It was. The larger the relative power value obtained, the higher the thermoelectric conversion capability. Table 2 shows the electromotive force value of each thermoelectric conversion element as a relative value.

<< Durability Evaluation >>
The stress relaxation ability of the heat exchange space was evaluated as follows.

  Each thermoelectric conversion element was allowed to stand in a freezer at −40 ° C. for 30 seconds and then left on a hot plate at 120 ° C. for 30 seconds, and the above-described thermoelectric conversion efficiency evaluation was performed. The cooling air was measured while flowing parallel to the cooling surface, and the value is shown as a relative value with the value of the thermoelectric conversion element 22 being 100.

  As is apparent from Table 2, the thermoelectric conversion element of the present invention has almost no difference in conversion efficiency because the main shaft of the heat exchange fin adheres to the pipe whether it is attached in parallel or perpendicularly to the main shaft of the pipe. There is no. On the other hand, thermoelectric conversion elements with corrugated fin-type heat sinks are in close contact with the pipe because the heat exchange fin's rigidity and mutual interference become obstacles when the heat exchange fin's main axis is attached perpendicular to the pipe's main axis. And the difference in conversion efficiency occurs. It may be peeled off depending on the location. Even when the thermoelectric conversion element of the present invention is attached vertically, there is no obstacle because the coil expands and contracts.

  As described above, it can be seen that the thermoelectric conversion element of the present invention is excellent in both thermoelectric conversion efficiency and durability, and the thermoelectric conversion efficiency is not affected by the flowing direction of the heating medium or the cooling medium. Further, the thermoelectric conversion element of the present invention is not easily influenced by the shape of the heat source or the cooling source, and can efficiently perform thermoelectric conversion even when the surface is not smooth or has a complicated shape. I understand.

DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion element 10, 10 'Insulating board | substrate 11 High temperature side electrode board | substrate 12 Low temperature side electrode board | substrate 13 Junction space 14 P-type thermoelectric semiconductor 15 N-type thermoelectric semiconductor 16, 16' Spiral heat exchange fin

Claims (5)

  A pair of electrode substrates disposed opposite to each other, a thermoelectric conversion module in which a plurality of thermoelectric semiconductors are electrically connected to opposite inner surfaces of the electrode substrate, and at least one of the pair of electrode substrates A thermoelectric conversion element having heat exchange fins on the outer surface side thereof, wherein the heat exchange fins are helical heat exchange fins.   The thermoelectric conversion element according to claim 1, wherein the helical heat exchange fins are arranged so as to be parallel to each other.   The thermoelectric conversion element according to claim 1 or 2, wherein the helical heat exchange fin is made of a metal foil.   The thermoelectric conversion element according to any one of claims 1 to 3, wherein the spiral heat exchange fins are arranged on both of the electrode substrates.   The thermoelectric conversion element according to any one of claims 1 to 4, wherein a ratio of a length of the helical heat exchange fin to a diameter is 2 or more.

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