JP2006100346A - Thermoelectric conversion system and method of manufacturing thermoelectric panel therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric conversion system that can be procured inexpensively in a large amount and utilizes a highly economical low-temperature heat source, and to provide a method of manufacturing a thermoelectric panel for the thermoelectric conversion system. <P>SOLUTION: The thermoelectric conversion system is provided with a serial unit and a load R<SB>L</SB>which is directly connected between the anode terminal and cathode terminal of the serial unit. The serial unit is constituted in the alternative serial connection structure of a plurality of p-type conductor elements 1<SB>1</SB>-1<SB>n</SB>composed of Fe, and a plurality of n-type conductor elements 2<SB>1</SB>-2<SB>n</SB>composed of an Fe-Al alloy by alternately arranging the conductor elements 1<SB>1</SB>-1<SB>n</SB>and 2<SB>1</SB>-2<SB>n</SB>in an accordion fold structure. The elements 1<SB>1</SB>-1<SB>n</SB>and 2<SB>1</SB>-2<SB>n</SB>are connected to each other to form first p-n junctions in the plurality of crest sections of the accordion fold structure, and second p-n junctions in the plurality of valley sections of the structure. Thus, an electromotive force is obtained by the Seebeck effect by giving different temperatures to the first and second p-n junctions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an energy-related field, and more particularly, to a thermoelectric conversion system using a low-temperature heat source and a method for manufacturing a thermoelectric panel for the thermoelectric conversion system.

Currently, the amount of carbon dioxide released by fossil fuels such as oil, coal, and natural gas is reaching the limit for environmental impacts such as global warming and pollution, and there is a social demand for the introduction of a clean energy system. . For this realization, an economical and stable supply of hydrogen (H ₂ ) is expected.

  On the other hand, there are various types of low-temperature heat sources such as power plant waste heat and steel mills, waste incineration plants, and various factory waste heat, but they have been dumped without utility value. Natural energy such as hot rock underground heat and regenerative solar heat can also be used as a low-temperature heat source.

  Industrial production methods for hydrogen include methods based on high-temperature chemical reactions such as coal water-gas reactions, natural gas and coke oven gas, and reforming reactions of alcohols, and electrolysis of water at room temperature. Are known. However, in the method based on the high temperature chemical reaction, the natural fuel reforming reaction requires a high temperature heat source, and carbon monoxide and carbon dioxide are by-produced. I can't escape the disadvantage of sex.

  On the other hand, the production of hydrogen by electrolysis of water is currently performed by a system via a DC power supply device for low voltage and large current using general industrial power generated by thermal power, nuclear power, and hydroelectric power generation. Moreover, although the utilization of the solar power generation by a silicon semiconductor is also considered, the electric power is more expensive than the existing power generation system. Therefore, it is difficult to stably produce inexpensive hydrogen in the country where the unit price of electricity, which is constantly changing, is high.

A thermoelectric conversion system that uses a semiconductor thermoelectric conversion element with a high figure of merit and targets a heat source of 500 ^° C. or more has been put to practical use for extremely small-scale power generation. This thermoelectric material is a compound semiconductor made of a rare element. For example, n-type bismuth, tellurium, selenium (Bi ₂ (Te, Se) ₃ ), p-type bismuth, antimony, (tellurium (Bi, Sb) ₂ Te ₃ ). ) And other bismuth-tellurium-based compound semiconductors are known, but are not suitable for large-capacity power generation because they are difficult and expensive to secure in quantity. Furthermore, there are problems of low melting point and toxicity.

For this reason, iron (Fe) is selected as the p-type conductor element, and a low-temperature iron-based thermoelectric conversion element in which the n-type conductor element to be joined with the Fe-12 wt% Al alloy has been developed (non-non-conductive). (See Patent Documents 1 to 3.)
Katsutoshi Ono and three others "iron-based thermoelectric conversion element for low temperature", iron and steel, Japan Iron and Steel Institute, 1997, Vol. 83, No. 2, p. 73-77 Masahiro Masada and 4 others, “Seebeck effect and low-temperature heat source thermoelectric conversion characteristics of Fe—Al—Si alloy”, Iron and Steel, Japan Iron and Steel Institute, 1998, Vol. 84, No. 2, p. 70-74 Katsutoshi Ono and two others "Thermoelectric properties of the Fe-Al and Fe-Al-Si alloys for thermoelectric generation utilizing thermoelectric conversion for thermoelectric conversion using a low-temperature heat source low-temperature heat sources), steel research, September 1998, volume 69, p. 387-390

  An object of the present invention is to provide a thermoelectric conversion system using a low-temperature heat source that is inexpensive and can be procured in large quantities and is excellent in economy, and a method of manufacturing a thermoelectric panel for the thermoelectric conversion system.

In order to achieve the above object, the first feature of the present invention is that (a) a plurality of p-type conductor elements and a plurality of n-type conductors are formed by the first pn junction and the second pn junction. A series unit having an alternating series connection structure with a body element, giving different temperatures to the first pn junction and the second pn junction, and obtaining an electromotive force due to the Seebeck effect, and (b) the series unit This is a thermoelectric conversion system including a load directly connected between the anode terminal and the cathode terminal. Here, “alternate series connection structure of a plurality of p-type conductor elements and a plurality of n-type conductor elements” means that a plurality of p-type conductor elements made of iron and a plurality of n-type conductors made of iron / aluminum alloy are used. The body elements are alternately arranged in the bellows fold structure, and a plurality of peaks of the bellows fold structure constitute a first pn junction, respectively, and a plurality of valleys of the bellows fold structure each have a second p- It is connected so as to constitute an n junction.
The second feature of the present invention is:
(A) A wall-shaped terminal portion made of iron and a wall-shaped heat conduction portion made of iron and connected in an orthogonal direction so as to constitute the first L-shaped structure with the terminal portion, and the heat conduction portion The first L-shaped structure is connected to the first L-shaped structure and is bent in the opposite direction to form the second L-shaped structure, and the heat-conductive section is separated from the heat-conductive section. An iron side wall extending from the first joint forming part in parallel to the heat conducting part, a second iron joining forming part connected to the heat conducting part and the side wall part via a heat-resistant insulator, and heat A step of preparing a box-shaped container comprising a conduction plate, a first junction formation portion and a side wall portion, and a bottom plate connected to the bottom portion of the second junction formation portion via a heat-resistant insulator;
(B) painting a heat-resistant electrical insulator on the inner surface of the box-shaped container other than the first and second joint forming parts;
(C) A molten iron / aluminum alloy is cast into the container to form an n-type conductor element, and further, a first junction forming portion that becomes a p-type conductor element and an n-type conductor element by melt diffusion bonding Forming a first pn junction at an interface between the second junction forming portion and a second junction forming portion serving as a p-type conductor element, and a second pn junction at the interface between the n-type conductor element. The gist of the present invention is a method for manufacturing a thermoelectric panel for a thermoelectric conversion system.

According to the present invention, it is possible to provide a thermoelectric conversion system using a low-temperature heat source that is inexpensive and can be procured in large quantities and is excellent in economy, and a method for manufacturing the thermoelectric panel for the thermoelectric conversion system. In particular, when applied to water electrolysis, the durability of the system is semi-permanent, and there is no need for attached electronic and electrical equipment, and free low-temperature heat sources and natural water such as seawater, river water, groundwater, and rainwater are used. Thus, hydrogen (H ₂ ) can be generated while adapting to a large amount of demand economically in a sustainable and renewable form.

  As shown in FIG. 1A, a p-type conductor element 1 and an n-type conductor element (2a, 2b) are joined at two points, and different temperatures θh, θc (θh> θc) are applied to the respective joints. Is applied, an electromotive force e is generated in the circuit due to the Seebeck effect, and a current i flows through the load R. Here, the p-type conductor element 1 is a hole conductive material, and the n-type conductor elements (2a, 2b) are electron conductive materials. In this way, thermoelectric conversion based on the Seebeck effect of a substance belongs to the form of direct energy conversion that converts thermal energy into electrical energy, so it can be advantageously used as a neglected power generation method that does not require a mechanical drive unit. I can expect.

Further, as shown in FIG. 1B, n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n and a p-type conductor element made of a hole conductive material. 1 ₁ , 1 ₂ , 1 ₃ ,..., 1 _n−1 , 1 _n are joined at the corresponding n high temperature side junctions and n−1 low temperature side junctions, respectively. Apply junction temperatures θh ₁ , θh ₂ , θh ₃ ,..., Θh _n-1 , θh _n and low-temperature side junction temperatures θc ₁ , θc ₂ , θc ₃ , ..., θc _n-1 Then, an electromotive force V is generated in the circuit:
V = Δα (θh ₁ −θc ₁ ) + Δα (θh ₂ −θc ₂ ) + ・ ・ ・ ・ ・ + Δα (θh _n −θc _n )
(1)
Next, first and second embodiments of the present invention based on the above principle will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings. The first and second embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is The material, shape, structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

(First embodiment)
The thermoelectric conversion system according to the first embodiment of the present invention includes a plurality of p-type conductor elements 1 ₁ , 1 ₂ , 1 made of iron (Fe) as shown in the schematic diagram (conceptual diagram) of FIG. ₃ ,..., 1 _n−1 , 1 _n and a plurality of n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,. _n-1 and _2n are alternately arranged in a bellows fold structure, a plurality of peak portions of the bellows fold structure form a first pn junction, and a plurality of valley portions of the bellows fold structure respectively. Are connected to form a plurality of p-n junctions, whereby a plurality of p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ ,..., 1 _n−1 , 1 _n and a plurality of n _- type conductors are connected. Body elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n are connected in series, and different temperatures are applied to the first and second pn junctions, Due to the Seebeck effect A series unit for obtaining an electromotive force and a load _RL directly connected between an anode terminal and a cathode terminal of the series unit are provided. As with semiconductors, p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ ,..., 1 _n−1 , 1 _n made of iron (Fe) are hole-conducting materials, and iron / aluminum ( The n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n made of (Fe—Al) alloy are electron conductive materials. n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n and p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ ,. .., 1 _n-1 and 1 _n are peak portions of the bellows fold structure, and corresponding n high temperature side joint surfaces J _h1 , J _h2 , J _{h3 ,. 1} and J _hn constitute a first pn junction. Also, n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n and hole-conducting material p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ ,. ..., 1 _n−1 , 1 _n are valley portions of the bellows fold structure, and corresponding (n−1) low temperature side joint surfaces J _c1 , J _c2 , J _c3,. .., J _cn-1 forms a second pn junction. Then, a series connection structure of _n thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n is configured by the bellows fold structure shown in FIG.

  FIG. 3 is an example of a specific structure of a thermoelectric panel (series unit) used in the thermoelectric conversion system according to the first embodiment of the present invention. As shown in FIG. 10, in the thermoelectric conversion system according to the first embodiment, a plurality (m) of series units are connected in parallel, thereby reducing the overall impedance and adjusting the impedance with the load. Although the thermoelectric panel which performs this can be configured, it will be appropriately referred to as a “thermoelectric panel” including the case where m = 1.

In Figure 3, p Katashirube conductor elements 1 _j-1 of the belt-shaped bent in _{S-shape, 1 j, 1 j + 1} , 1 j + 2, ·····, and 1 _n-1, 1 _n The n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _{n in a} straight line (flat plate shape) are n thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n constitute a series unit (thermoelectric panel) electrically connected in series. P-type conductor elements 1 _j−1 , 1 _j , 1 _{j + 1} , 1 _{j + 2} ,..., 1 _n−1 , 1 _n , The band-shaped n-type conductive n-type conductive elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n are equal in width to each other.

The n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n are Fe—Al alloys having an Al composition of 6 to 15% by weight. Preferably, the composition of Al is 7 to 12% by weight. Fe-Al alloys, for machining the hardness and brittleness is larger and it is difficult, n Katashirube conductor element _{2 j-1, 2 j,} 2 j + 1, the stress of the bent portion of the ..... The p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ ,..., 1 _n-1 , 1 _{n, which} are configured in a straight line so as not to be applied, are less hard and brittle and can be machined. Since it is easy, each is bent into an S shape. As a result, the high-temperature side joint surfaces J _h1 , J _h2 , J _h3 ,..., J _hn−1 , J _hn and the low-temperature side joint surfaces J _c1 , J _c2 , J _c3,. Both _cn-1 are not at the top and the valley of the bent structure, but at the positions respectively moved from the top and the valley to the inside.

And between the p-type conductor element 1 ₁ and the n-type conductor element 1 ₁ facing each other, between the p-type conductor element 1 ₂ and the n-type conductor element 2 _2, and the p-type conductor element 1 _3. Between the n-type conductor element 2 ₃ ,... Between the p-type conductor element 1 _n-1 and the n-type conductor element 2 _n-1, and between the p-type conductor element 1 _n and n The low temperature side insulating films 3 _c1 , 3 _c2 , 3 _c3 ,..., 3 _cn−1 , 3 _cn are inserted between the _n type conductor elements 2 _n and the _n type conductors that oppose each other. between the elements 2 ₁ and p Katashirube conductor element 1 _2, between the n Katashirube conductor element 2 ₂ and p Katashirube collector element 1 _3, ..., a n Katashirube conductor element 2 _n-1 High temperature side insulating films 3 _h1 , 3 _h2 ,..., 3 _hn−1 are inserted between the p-type conductor elements 1 _n , respectively.

The low temperature side insulating films 3 _c1 , 3 _c2 , 3 _c3 ,..., 3 _cn−1 , 3 _cn and the high temperature side insulating films 3 _h1 , 3 _{h2 ,.} Various materials can be used as long as they have high electrical insulation and can withstand the use temperature, and are not limited to specific materials and structures. For example, you may comprise with a multilayer structure as shown in FIG. In FIG. 4, the low temperature side insulating film 3 _cj has a five-layered structure of insulating films 301 _j , 302 _j , 303 _j , 304 _j , and 305 _j , and the high temperature side insulating film 3 _hj is formed of the insulating films 301 _{j + 1} , 302 _{j + 1} , 303 _{j + 1} , 304 _{j + 1} , 305 _{j + 1} , 306 _{j + 1, which has} a six-layered structure, and the low temperature side insulating film 3 _{cj + 1} is the insulating film 301 _{j + 2} , 302 _Although an example of a multi-layer structure of six layers _{j + 2} , 303 _{j + 2} , 304 _{j + 2} , 305 _{j + 2} , and 306 _{j + 2} is shown, a single layer may be used, and two to four layers or seven layers may be used. Various structures such as those described above can be employed.

The thermoelectric conversion system according to the first embodiment shown in FIGS. 2 and 3 has n thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n. Since the series unit (thermoelectric panel) is electrically connected in series, the open circuit voltage V of the entire series unit generates a DC electromotive force that is n times the electromotive force of one thermoelectric conversion element unit. . That is, in Equation (1), the high-temperature side junction temperatures are equal to each other and θh ₁ = θh ₂ = θh ₃ =... = Θh _n-1 = θh _n and the low-temperature side junction temperatures are equal to each other θc ₁ = θc ₂ = If θc ₃ = ・ ・ ・ ・ ・ = θc _n-1 = θc _n ,
V = nΔαΔθ (2)
Here, Δα is the Seebeck coefficient of the thermoelectric conversion element unit, that is, the electromotive force of one thermoelectric conversion element unit with respect to a temperature difference of 1 K, and Δθ is the high-temperature side joint surface J _h1 , J _h2 , J _h3 ,. _.. , J _hn−1 , J _hn and the low-temperature side joint surfaces J _c1 , J _c2 , J _c3 ,..., J _cn−1 , J _cn . High-temperature side joint surfaces J _h1 , J _h2 , J _h3 ,..., J _hn−1 , J _hn are changed to θh (= θh ₁ = θh ₂ = θh ₃ = ・ ・ ・ ・ ・ = θh _n-1 = θh _n ), and the low-temperature side joint surfaces J _c1 , J _c2 , J _c3 ,..., J _cn−1 , J _cn are θc (= θc ₁ = θc ₂ = θc ₃ = ・ ・ ・ ・ ・ = θc _n-1 = θc _n )
Δθ = θh−θc (3)
It is.
In the thermoelectric conversion system according to the first embodiment, as shown in FIG. 2, a load having a resistance value R _L is connected in series to a series unit (thermoelectric panel). If the current I flows through the entire series circuit, the output W for the load is given by equation (4).

W = nΔαΔθI−R _G I ² (4)
Here, R _G is the total resistance of _n thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n constituting the series unit. The second term on the right side is Joule heat loss in the series unit. The output of equation (4) is that current I is I = nΔαΔθ / 2R _G (5)
And becomes the maximum and is expressed by equation (6).

W _max = (nΔαΔθ) ² / 4R _G (6)
The amount of hydrogen (H ₂ ) generated in the electrolysis of water is proportional to the electrolysis current. Therefore, as shown in FIG. 9 or 10, the anode terminal of the series unit (thermoelectric panel) is directly connected to the anode plate 42 arranged in the water electrolysis tank 41, and the cathode terminal of the series unit is arranged in the water electrolysis tank 41. Directly connected to the cathode plate 43 thus formed, the resistance of water between the anode plate 42 and the cathode plate 43 is used as a load, and water electrolysis is generated inside each thermoelectric conversion element unit constituting the series unit. Since a current corresponding to the amount of hydrogen flows, it is required to reduce the electric resistance of the thermoelectric conversion element unit, as is apparent from Equation (5).

Table 1 shows that Fe (Fe) having an absolute Seebeck coefficient α _p = + 12 μV / K at room temperature as a _p -type conductor element and Fe − having an absolute Seebeck coefficient α _n = −20 μV / K as an _n -type conductor element. The measurement result of the physical property which concerns on the thermoelectric performance at the time of using Al alloy (Al: 6-15 weight%) is shown.

  Iron (Fe) as a p-type conductor element and an Fe-Al alloy (Al: 6 to 15 wt%, preferably 7 to 12 wt% Fe-Al alloy shown in Table 1 as p-type conductor elements) .) Is inexpensive and excellent in mass productivity. Furthermore, as can be seen from Table 1, it has good conductivity.

The value of the Seebeck coefficient of the thermoelectric conversion element unit shown in Table 1 is on the order of 1/10 compared to a compound semiconductor thermoelectric conversion element that can be used at a low temperature of 300 ^° C. or less. Therefore, ten times the number of serial couplings n of thermoelectric conversion element units (n is a positive integer of 2 or more, but generally can take a value of several hundred to 1,000 or more), but Fe and Fe—Al alloy This combination has a significant advantage in terms of price, consumable amount, and processability to a thermoelectric conversion element unit.
Furthermore, since the thermoelectric conversion system according to the first embodiment uses a metal-based thermoelectric conversion element unit, unlike the semiconductor thermoelectric conversion element, the Seebeck coefficient varies very little due to a small amount of impurities. Therefore, ordinary steel and steel scrap can be used as the p-type conductor element. Further, the Fe—Al alloy as the n-type conductor element can be alloyed using aluminum scrap containing iron. Further, even if aluminum oxide inclusions produced during melting are present in the alloy, the influence on the thermoelectric properties is hardly recognized.

Furthermore, in the thermoelectric conversion system according to the first embodiment, as shown in the conceptual diagram of the system of FIG. 2, when a high-temperature gas is applied as a heat source, the side surface of the heat source region includes a large number of thermoelectric conversion element unit groups. A thermoelectric panel (series unit) is provided, and terminals of the thermoelectric panel are directly connected to an anode (anode plate) 42 and a cathode (cathode plate) 43 in the water electrolysis tank 41. Therefore, the thermoelectric conversion system according to the first embodiment does not include an operation auxiliary power source and a mechanical drive unit, and includes only a thermoelectric panel (series unit), a low-temperature heat source, and a water electrolysis tank 41 as materials. If the system is left in a steady state, hydrogen (H ₂ ) and oxygen (O ₂ ) are continuously generated.

Regarding the shape of each thermoelectric conversion element unit used in the thermoelectric conversion system according to the first embodiment, in particular, the respective high temperature side joint surfaces J _h1 , J _h2 , J _h3 ,..., J _{hn− 1} and J _hn and the low-temperature-side joint surfaces J _c1 , J _c2 , J _c3 ,..., J _cn−1 , J _cn are distances L between the joint surfaces. Further, p Katashirube conductor elements ₁ 1, 1 _2, 1 _3, · · · · ·, 1 _n-1, 1 _n the cross-sectional area of S _p and n Katashirube conductor element 2 _{1, 2} 2, 2 _3, · ..., 2 _n−1 , 2 _n cross-sectional areas _Sn are important factors for the performance of the thermoelectric conversion element unit. That is, the resistivity of the n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n is ρ _n , and the p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ , ..., 1 _n-1 , 1 _n specific resistance ρ _p , high temperature side joint surface J _h1 , J _h2 , J _h3 ,..., J _hn-1 , J _hn r _ch , assuming that the contact resistance at the low temperature side joint surfaces J _c1 , J _c2 , J _c3 ,..., J _cn-1 is r _cc , n thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n thermoelectric panel (series unit) terminal resistance R _G is
R _G = n (ρ _n L / S _n + ρ _p L / S _p + r _ch + r _cc ) (7)
It becomes. Further, the thermal conductivity of the n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n-1 , 2 _n is κ _n , and the p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ , ..., 1 if _n-1, 1 a thermal conductivity of _n and kappa _p, n pieces of the thermoelectric conversion element unit _{51 1, 51 2, 51 3} , ·····, 51 n- The thermal resistance R _th of the thermoelectric panel consisting of ₁ and 51 _n is
1 / R _th = n (κ _{n Sn} / L + κ _{p Sp} / L) (8)
It becomes. Therefore, the high temperature side joint surfaces J _h1 , J _h2 , J _h3 ,..., J _hn−1 , J _hn to the low temperature side joint surfaces J _c1 , J _c2 , J _{c3 ,. The} heat flow rate Q flowing to _-1 is
Q = Δθ / R _th (9)
It becomes.

In the thermoelectric conversion system according to the first embodiment, the thermoelectric panel (series unit) is directly connected to the water electrolysis device (41, 42, 43), and includes one DC power supply and two resistors R _C and R _G. Since they constitute a closed circuit, they operate in conjunction with each other. As is clear from the derivation process of Equation (6), the condition that maximizes the output of the thermoelectric panel is between the resistance R _C between the water electrolyzer terminals and the resistance R _G between the thermoelectric panel terminals.
R _G = R _C (10)
This is when the relationship is established. In order to increase the circuit current that becomes a carrier for hydrogen generation in the electrolysis of water while maintaining the relationship of the equation (10), both the resistance R _C between the water electrolyzer terminals and the resistance R _G between the thermoelectric panel terminals are used. It is preferable to reduce the resistance.
Regarding the energy balance in the electrolysis of water that has been carried out conventionally, the total required heat amount such as water decomposition reaction endotherm, electrolytic cell heat amount to maintain the optimal electrolytic bath temperature of 70 to 80 ^° C., and heating temperature of the feed water Is compensated by the bath resistance Joule heat of the electrolysis current. Therefore, in this case, since the bath resistance (resistance between water electrolysis cell terminals) _RC is proportional to the distance between the anode 42 and the cathode 43, the distance between the electrodes cannot be reduced below a certain limit. In the thermoelectric conversion system according to the embodiment, part of the low-temperature heat source used for power generation is used, and the heat exchanger is immersed in the bath to compensate for the required amount of heat, so the distance between the anode 42 and the cathode 43 is extremely small. It is possible to reduce the resistance R _C between the water electrolyzer terminals.

On the other hand, regarding the inter-terminal resistance R _G of the thermoelectric panel, a series unit composed of _n thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n is shown in FIG. As shown in Fig. 4, m can be reduced by connecting in parallel (m is a positive integer of 2 or more) to form an n × m matrix thermoelectric panel.

  The theoretical decomposition voltage for water electrolysis is 1.2V, and conventional water electrolysis is performed at an electrolysis voltage of 1.7 to 2.0V. In the water electrolysis apparatus (41, 42, 43) used in the thermoelectric conversion system according to the first embodiment, an electrolysis voltage of 1.5 V is used at the minimum due to the improved design of the water electrolysis tank 41.

Since the metal-based thermoelectric conversion element has a large thermal conductivity κ as shown in Table 1, the temperature difference of the heat source:
ΔT = T _h −T _C (11)
In contrast, each of the thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _{n represented} by the formula (3) is connected to each high-temperature side joint surface J _h1. , J _h2 , J _h3 ,..., J _hn-1 , J _hn and the temperature between the low-temperature side joints J _c1 , J _c2 , J _c3 , ..., J _cn-1 , J _cn In order to bring the difference Δθ close to ΔT, the high-temperature heat sink part is equipped with high-capacity heating fins on the high-temperature side joint surfaces J _h1 , J _h2 , J _h3 , ..., J _hn-1 , J _hn. the provided low temperature side bonding surface _{J c1, J c2, J c3} , ·····, J cn-1, J cn should enhance the cooling effect closer to the cooling fins on the p-n junction plane.
In the thermoelectric conversion system according to the first embodiment, the thermoelectric panels 53 are directly connected to the water electrolysis apparatus (41, 42, 43), as shown in the equivalent circuit of FIG. 10, and one of the DC power supply V _G Since they constitute a closed circuit composed of two electric resistances R _G and R _C , both operate in conjunction with each other. Between resistance R _G between thermoelectric panel terminals and resistance R _C between water electrolyzer terminals
R _G < _RC (12)
Therefore, it is necessary to design the thermoelectric panel 53 and the water electrolysis tank 41 so that the above relationship is established. As is clear from the derivation process of Equation (6), the output of the thermoelectric panel 53 is maximum when R _G = R _C , but if R _G > R _C, if a circuit current flows, This is because the voltage drop becomes larger than the voltage drop in the water electrolysis tank 41, which is disadvantageous. Further, since the circuit current I serves as a carrier for hydrogen generation in the electrolysis of water, it is desirable to reduce the total electric resistance in the closed circuit.
In the electric circuit of FIG. 10, when the circuit current I is flowing, if the open-circuit voltage of the thermoelectric panel 53 was V _G,
V _G = I (R _G + R _C ) (13)
Therefore, the voltage V _C applied between the terminals of the water electrolysis tank 41 is given by the equation (14).

V _C = V _G / (R _G / R _C +1) (14)
The open circuit voltage V _G which is required for the thermoelectric panel 53 to be connected to the water electrolyser 41 of V _C = 1.5V, determined as a function of the (R _G / R _C) ratio, required to generate the respective V _G Thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n in series connection number n and thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,. .., 51 _n-1 , 51 _n high-temperature side joint surfaces J _h1 , J _h2 , J _h3 ,..., J _hn-1 , J _hn and low-temperature side joint surfaces J _c1 , J _c2 , J _c3 , ..., J _cn−1 , J _cn are related to the temperature difference Δθ.

As described above, according to the thermoelectric conversion system according to the first embodiment of the present invention, a series unit (element series coupling) corresponding to a generator using a thermoelectric conversion element made of a metal-based inexpensive thermoelectric material. And a system that generates hydrogen in an amount proportional to the circuit current, directly connected to the water electrolysis device (41, 42, 43) serving as a load without interposing electronic devices such as rectifiers. Can do. In the thermoelectric conversion system according to the first embodiment, as a heat source for large-capacity conversion, “utility” is more important than “efficiency”, and the temperature is mainly discarded because it has no utility value. It is possible to directly extract DC power necessary for electrolysis of water using a free low-temperature heat source of ^o C or less.
The manufacturing method of the serial unit used for the thermoelectric conversion system which concerns on the 1st Embodiment of this invention is demonstrated using FIG. The serial unit manufacturing method described below is merely an example, and it is needless to say that the present invention can be realized by various other manufacturing methods including this modification.

(A) First, as shown in FIG. 5A, a strip of iron (cold rolled steel sheet) having a thickness t = 0.06 mm to about 0.2 mm and a width of about 5 to 20 mm is prepared. The thickness t of the cold-rolled steel sheet may be determined in consideration of the diffusion depth of aluminum (Al). That is, the thickness t at which the cold-rolled steel strip is completely Fe-Al alloy is selected by Al diffused from both the front and back surfaces of the cold-rolled steel strip. The width of the cold-rolled steel strip depends on the design of the resistance _RG between the thermoelectric panel terminals, but is arbitrary if parallel connection is considered. The width of the cold-rolled steel sheet preferably takes into account the ease of subsequent bending.

  (B) Thereafter, as shown in FIG. 5 (b), 6-15% by weight of the cold-rolled steel sheet, preferably 7-12% by weight, per unit length, in the portion to be the n-type conductor element formation scheduled part. The aluminum foils 12a, 12b, 12c,... Having a weight corresponding to are wound periodically at regular intervals. That is, the aluminum foils 12a, 12b, and 12c having a thickness corresponding to 1/2 to 6 to 15% by weight, preferably 7 to 12% by weight of the weight of the iron (Fe) band having a thickness t per unit length. Wrapped around a strip of cold-rolled steel sheet.

(C) Further, diffusion annealing is performed for 24 hours at 1000 ^° C. in an argon (Ar) gas atmosphere. By this treatment, as shown in FIG. 5 (c), Al diffuses at the positions of the aluminum foils 12a, 12b, 12c,... And is alloyed with Fe. As a result, the n-type conductor elements 2 _j-1 , 2 _j , 2 _{j + 1} ,... Made of Fe—Al alloy having an Al composition of 6 to 15 wt%, preferably 7 to 12 wt%. Are periodically formed at regular intervals, and the positions of the strips of the cold-rolled steel sheet on which the aluminum foil is not wound are located at the p-type conductor elements 1 _j-1 , 1 _j , 1 _{j + 1} , 1 _{j + 2} , Are formed periodically at regular intervals. As a result, the interface between the p-type conductor element 1 _j-1 and the n-type conductor element 2 _j-1 , the interface between the n-type conductor element 2 _j-1 and the p-type conductor element 1 _j , p-type conductivity Interface between body element 1 _j and n-type conductor element 2 _j , interface between n-type conductor element 2 _j and p-type conductor element 1 _{j + 1} , p-type conductor element 1 _{j + 1} and n-type conductor A pn junction is formed at each of the interface between the body element 2 _{j + 1} and the interface between the n-type conductor element 2 _{j + 1} and the p-type conductor element 1 _{j + 2} .

(D) Next, as shown in FIG. 5 (d), 1 to 5 mm approximately from the junction, preferably p Katashirube conductor elements 1 _j-1 position spaced about 2 to 3 mm, 1 _j, 1 _{j The position of +1} , 1 _{j + 2} ,... Is set as a folding position, and at this folding position, a mountain fold and a valley fold are repeated alternately, and then sequentially bent in a U-shape in the opposite direction. Fe-Al alloys, for machining the hardness and brittleness is larger and it is difficult, n Katashirube conductor element _{2 j-1, 2 j,} 2 j + 1, the stress of the bent portion of the ..... The position of each joint is shifted from the bending position so that it is not applied. For this reason, on both the high temperature side and the low temperature side, the pn junction surface is not the top and the valley at the folding position, but is about 2 to 10 mm, preferably about 3 to 5 mm from the top and the valley of the bellows fold structure. It is in the moved position. As a result, a series unit having a bellows fold structure as shown in FIG. 5D is completed.

The overall performance of the thermoelectric conversion system according to the first embodiment is that of the thermoelectric characteristics indicated by the individual thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n . is determined by the additive, the thermoelectric conversion element unit _{51 1, 51 2, 51 3} , ·····, 51 n-1, 51 if this series combination number n of _n may become a thousand or more of several hundred It is convenient to use a meander line (meandering line) pattern as shown in FIG. That is:
(A) Using a cold-rolled steel sheet having a thickness of about 0.2 mm and a plane size of about 0.38 m × 2.5 m, cut into a meander line shape with a line width of 10 mm that bends at right angles as shown in FIG. For the cutting, a press may be used, or a gold cutter or cutter may be used, and various means can be employed. As shown in FIG. 6, parallel slits having a width of 5 mm are provided between adjacent meander lines to form a periodically repeated pattern.

(B) The n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n are 6 to 15 wt%, preferably 6 to 15 wt%, Is closely contacted with an aluminum foil having a length of 46 mm corresponding to an alloying amount of 7 to 12% by weight, and is subjected to diffusion annealing at 1000 ^° C. for 24 hours in an argon atmosphere. As a result, n-type conductor elements 2 ₁ ,..., 2 _j , 2 _{j + 1} ,... Made of Fe—Al alloy having an Al composition of 6 to 15% by weight, preferably 7 to 12% by weight. ..., 2 _n−1 , 2 _n are periodically formed at regular intervals, and the p-type conductor elements 1 ₁ ,. .., 1 _j , 1 _{j + 1} ,..., 1 _n−1 , 1 _n are periodically formed at regular intervals. As a result, the interface between the n-type conductor element 2 ₁ and the p-type conductor element 1 ₁ ,..., The interface between the p-type conductor element 1 _j-1 and the n-type conductor element 2 _j , n Interface between p-type conductor element 2 _j and p-type conductor element 1 _j , interface between p-type conductor element 1 _j and n-type conductor element 2 _{j + 1} , n-type conductor elements 2 _{j + 1} and p interface between Katashirube conductor elements 1 _{j + 1,} the interface between the p Katashirube conductor elements 1 _{j + 1} and n Katashirube collector element _{2 j +} 2, ·····, p Katashirube conductor element 1 _n-1 A pn junction is formed at the interface between the n-type conductor element 2 _n and the interface between the n-type conductor element 2 _n and the p-type conductor element 1 _n, and a steel plate of 0.38 m × 2.5 m A series unit flat type composed of n = 625 sets of thermoelectric conversion element units connected in series is obtained. Similarly, the same treatment is performed on the nine steel plates to produce a total of 10 series unit flat molds (m = 10).

(C) Next, p Katashirube conductor elements ₁ 1 position slightly deviated each joint as shown in FIG. _{7, ·····, 1 j, 1} j + 1, ·····, 1 n _-1 and 1 _n are bent at the bending positions B _c1 , B _h1 ,..., B _cn and B _hn , and are alternately and alternately bent in the opposite direction to form a bellows fold structure. Then, thick paper is inserted into all adjacent gaps to provide electrical insulation, and a series unit is obtained. Similarly, the same processing is further performed on the nine series unit flat molds to produce a total of 10 series units (m = 10). When the electrical resistance between the terminals was measured for 10 series units, the average was 17.2Ω. In addition, when 10 series units were connected in parallel to form a thermoelectric panel, and the electrical resistance between the terminals of this thermoelectric panel was measured, it was 1.83Ω.

(D) Next, as shown in FIG. 8, these thermoelectric panels are arranged in a wind tunnel including an upper wall 35 and a lower wall 37, and two channels, a high temperature side channel 31 and a low temperature side channel 32, are formed by the inner wall 36. Partition. And hot air and cold air are sent into the high temperature side channel 31 and the low temperature side channel 32, respectively. For example, when a temperature difference of 127 ^° C. is applied to the joint portion of the element in a steady state, the open circuit voltage between the terminals of the thermoelectric panel 53 at this time is 2.05V.

Regarding the water electrolysis tank 41 connected to the terminals of the thermoelectric panel 53, an 80 ^° C., 28% KOH aqueous solution is used as the electrolyte, the anode (anode plate) 42 is a 20 mm × 20 mm nickel-plated steel plate, and the cathode (cathode plate) 43 is Normal steel plates with the same dimensions were used, and the distance between the electrodes was 100 mm. The inter-terminal resistance of this water electrolysis tank 41 was 24.7Ω. Therefore, the (R _G / R _C ) ratio is 0.074, which satisfies the relationship of Expression (12), which is a condition of an electric circuit for directly connecting the water electrolysis device (41, 42, 43) to the thermoelectric panel 53. ing. In this case, when the circuit composed of the thermoelectric panel 53 and the water electrolysis tank 41 is closed, a current of 0.077 A flows through the circuit and water is electrolyzed, and 6.15 Ncm ³ of hydrogen gas can be collected in 24 hours.

(Second Embodiment)
The thermoelectric conversion system according to the second embodiment of the present invention has a plurality of p-type conductor elements 1 _{1 made of} iron (Fe), similar to FIG. 2 of the thermoelectric conversion system according to the first embodiment. 1 ₂ , 1 ₃ ,..., 1 _n−1 , 1 _n and a plurality of n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,. .., 2 _n-1 , 2 _n are alternately arranged in a bellows fold structure, and a plurality of peak portions of the bellows fold structure constitute a first pn junction, and a plurality of valley portions of the bellows fold structure Are connected to form a second pn junction, whereby a plurality of p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ ,..., 1 _n−1 , 1 _n and a plurality N-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n are connected in series and are different from each other in the first and second pn junctions. Give temperature and z A series unit (thermoelectric panel) for obtaining an electromotive force by the Beck effect, and a load _RL directly connected between an anode terminal and a cathode terminal of the series unit. Here, n-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ ,..., 2 _n−1 , 2 _n and p-type conductor elements 1 ₁ , 1 ₂ , 1 ₃ ,. , 1 _n−1 , 1 _n are n high temperature side joint surfaces J _h1 , J _h2 , J _h3 ,..., J _hn−1 , J _{hn in} the peak portion of the bellows fold structure. in constitute a first p-n junction, respectively, in the valleys, the corresponding (n-1) pieces of the low temperature side joint surface _{J c1, J c2, J c3} , ·····, in J _cn-1 The second pn junctions are respectively configured, and thereby n thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n are configured.

As shown in FIG. 10, in the thermoelectric conversion system according to the second embodiment, a plurality (m) of serial units are connected in parallel, thereby reducing the overall impedance and adjusting the impedance with the load. Although it is possible to configure a thermoelectric panel for performing the above, including “when m = 1”, appropriately referred to as “thermoelectric panel” is the same as in the description of the thermoelectric conversion system according to the first embodiment.

  FIG. 11 is a schematic bird's-eye view showing a state in which three thermoelectric conversion element units are connected in a series unit having n series connections. FIG. 14 is a top view showing a state in which seven thermoelectric conversion element units among the series units having the number n of series couplings are connected. In the thermoelectric conversion system according to the first embodiment, the thermoelectric conversion element unit used also in the thermoelectric panel of the thermoelectric conversion system according to the second embodiment, as described using the formula (2) or Table 2. (The number n in series connection) is very large. For this reason, the structure of the thermoelectric conversion element unit has a simple structure that can be assembled by a flow operation when producing a thermoelectric panel.

In particular, the n-type conductor elements 2 _j−1 , 2 _j , 2 _{j + 1} ,... And the p-type conductor elements 1 _j−1 , 1 _j , 1 _{j + 1} ,. Among them, the n-type conductor elements 2 _j−1 , 2 _j , 2 _{j + 1} ,... Are difficult to machine because of their high hardness and brittleness. Therefore, as shown in FIG. 11, p-type conductor elements 1 _j-1 , 1 _j electrically insulated by the insulating films 4 _j-1 , 4 _j , 4 _{j + 1} ,... , 1 _{j + 1} ,... To form an n-type conductor element 2 _j−1 , 2 _j , 2 _{j + 1} ,. A high-temperature side junction surface J _hj-1 is formed at the interface between the p-type conductor element 1 _j-1 and the n-type conductor element 2 _j-1, and the n-type conductor element 2 _j-1 and the p _- type conductor A low-temperature-side bonding surface J _cj-1 is formed at the interface with the element 1 _j . Further, a high-temperature side junction surface J _hj is formed at the interface between the p-type conductor element 1 _j and the n-type conductor element 2 _j, and the n-type conductor element 2 _j and the p-type conductor element 1 _{j + 1} are A low-temperature-side joint surface J _cj is formed at the interface. Furthermore, a high-temperature side junction surface J _{hj + 1} is formed at the interface between the p-type conductor element 1 _{j + 1} and the n-type conductor element 2 _{j + 1,} and the n-type conductor element 2 _{j + 1} and the p-type conductor element A low-temperature-side bonding surface J _{cj + 1} is formed at the interface with the conductor element 1 _{j + 2} .

As shown in FIG. 12, the iron container is made of iron and has a wall-like terminal portion 1 _j, and the terminal portion 1 _j and the terminal portion 1 _j are made of iron and connected in an orthogonal direction so as to form a first L-shaped structure. The heat conducting portion 1 _j and the heat conducting portion 1 _j are connected to the heat conducting portion 1 _j so as to bend in the direction opposite to the first L-shaped structure, thereby forming a second L-shaped structure. a first bonding portion 1 _j of iron for the iron of the side wall portion 1 _j extending parallel to the heat-conducting portion from the first bonding portion 1 _j spaced from the heat conductive portion 1 _j, the heat-conducting portion 1 and _j and the side wall portion 1 _j and the second bonding portion 1 _{j + 1} of iron which are respectively connected via a heat insulator 71 _j, 72 _j, the heat-conducting portion 1 _j, the first bonding portion 1 _j and the side wall portion 1 _j are in a box shape having a bottom plate 9 _j connected to the bottom portion of the second bonding formation 1 _{j + 1} portion through a heat-resistant insulator. The heat conducting portion 1 _j and the first joint forming portion 1 _j are connected by overlay welding 81 _j . The first joint forming portion 1 _j and the side wall portion 1 _j are also connected by build-up welding 82 _j . As a result, the heat conducting portion 1 _j , the first junction forming portion 1 _j and the side wall portion 1 _j form a U-shape.

As shown in FIG. 11, each thermoelectric conversion element unit includes a high-temperature side electrode having iron heating fins 5 _j−1 , 5 _j , 5 _{j + 1} , and iron cooling fins 6 _j−1 , 6 _j , 6. low-temperature side electrode having _{j + 1} , p-type conductor elements 1 _j-1 , 1 _j , 1 _{j + 1} made of steel plate and n-type conductor elements 2 _j-1 , 2 _j , made of cast Fe—Al alloy 2 _{j + 1} (Al composition is 6 to 15% by weight, preferably 7 to 12% by weight) High-temperature side electrode having iron heating fins 5 _j-1 (first bonding formation) part) via a large n Katashirube conductor element 2 _j-1 of the cross-sectional area S _n from the reflux heat P _j-1 to the low-temperature side electrode having an iron cooling fins 6 _j-1 (second bonding section) At the same time flows through the Do p Katashirube conductor elements 1 _j-1 small cross-sectional area S _p from the hot-side electrode (first bonding portion) having a heating fin 5 _j-1 of iron, iron cooling fins The reflux heat P _j-1 flows to the low temperature side electrode (second junction forming portion) (not shown) having 6 _j-2 . Also, through the large n Katashirube conductor element 2 _j of the cross-sectional area S _n from the hot-side electrode (first bonding portion) having an iron heating fins 5 _j, the low-temperature side electrode having an iron cooling fins 6 _j At the same time (the second bonding portion) reflux heat P _j flows to the high temperature side electrode from the cross-sectional area S _p (first bonding portion) small p Katashirube conductor element 1 having an iron heating fins 5 _j Through _j , the reflux heat P _j flows to the low temperature side electrode (second junction forming portion) having the iron cooling fins 6 _j-1 . Furthermore, through the high temperature side electrode larger n Katashirube conductor element 2 _{j + 1} of the cross-sectional area S _n (first bonding portion) having a heating fin 5 _{j + 1} of the iron, iron cooling fins 6 _{j +} sectional area from the low temperature side electrode and at the same time (the second bonding portion) reflux heat P _{j + 1} flows to the high temperature side electrode having a heating fin 5 _{j + 1} of the iron (first bonding section) with ₁ The reflux heat P _j flows to the low temperature side electrode (second junction forming portion) having the iron cooling fins 6 _j through the p-type conductor element 1 _{j + 1} having a small S _p .

On the other hand, the current I _j-1 due to the Seebeck effect is, as shown in FIG. 11, from the p-type conductor element 1 _j-1 via the high temperature side electrode (first junction forming portion) to the high temperature side junction surface J _{hj−. 1} flows to the n-type conductor element 2 _j-1 , and then flows from the n-type conductor element 2 _j-1 to the p-type conductor element 1 _j via the low _- temperature side junction surface J _cj-1. . Furthermore, the current I _j = I _j-1 due to the Seebeck effect is transferred from the p-type conductor element 1 _j through the high-temperature side electrode (first junction formation portion) to the n-type conductivity via the high-temperature side junction surface J _hj. Flows to the body element 2 _j , and then flows from the n-type conductor element 2 _j to the p-type conductor element 1 _{j + 1} via the low-temperature side junction surface J _cj . Furthermore, the current I _{j + 1} = I _j due to the Seebeck effect passes from the p-type conductor element 1 _{j + 1} through the high temperature side electrode (first junction forming portion) via the high temperature side junction surface J _{hj + 1.} , Flows to the n-type conductor element 2 _{j + 1} , and then flows from the n-type conductor element 2 _{j + 1} to the p-type conductor element 1 _{j + 2} via the low-temperature side junction surface J _{cj + 1} . Therefore, between the given high-temperature side heat source temperature T _h and the low-temperature side refrigerant (atmosphere) temperature T _C , the high-temperature side joint surfaces J _hj−1 , J _hj , J _{hj + 1} ,. The design of the shape and dimensions of the thermoelectric conversion element unit for effectively giving the maximum temperature difference Δθ between the contact surface J _cj-1 , J _cj , J _{cj + 1,.} The design should be based on the heat transfer principle and experimental analysis. At that time, in particular, the respective high-temperature side joint surfaces J _hj−1 , J _hj , J _{hj + 1} ,... And the low-temperature side joint surfaces J _cj−1 , J _cj , J _{cj + 1,.} joining surface between the distance L ..., and p Katashirube conductor elements _{1 j-1, 1 j,} 1 j + 1, the cross-sectional area of · · · · · S _p and n Katashirube conductor element 2 _j-1, 2 _j, 2 j _{+ 1,} · · · · · of the cross-sectional area S _n is to become an important factor to the performance of the thermoelectric conversion element unit, described thermoelectric conversion system according to a first embodiment Street.

Regarding the energy balance in the electrolysis of water that has been carried out conventionally, the total required heat amount such as water decomposition reaction endotherm, electrolytic cell heat amount to maintain the optimal electrolytic bath temperature of 70 to 80 ^° C., and heating temperature of the feed water Is compensated by the bath resistance Joule heat of the electrolysis current. Therefore, in this case, since the bath resistance is proportional to the distance between the anode (anode plate) 42 and the cathode (cathode plate) 43, the distance between the electrodes cannot be reduced below a certain limit, but it is directly connected to the system of the present invention. In the water electrolysis apparatus (41, 42, 43), a part of the low-temperature heat source used for power generation is used, and the heat exchanger is immersed in the bath to compensate for the required amount of heat. It is possible to reduce the electrolytic cell terminal resistance _RC .

As described in the thermoelectric conversion system according to the first embodiment, regarding the inter-terminal resistance _RG of the thermoelectric panel, n thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,. .., 51 _n−1 , 51 _n can be reduced by m parallel connections (m is a positive integer of 2 or more) as shown in FIG.
Since the thermoelectric conversion element of the metal lines is larger thermal conductivity κ as shown in Table 1, each of the thermoelectric conversion element unit represented by formula _{(3) 51 1, 51 2} , 51 3, ·····, 51 n _-1, 51 each of the hot-side joint surface J, which is given to _{n h1, J h2, J h3} , ·····, J hn-1, J hn and cold side joint surface J _c1, J _c2, J _c3 In order to bring the temperature difference Δθ between J _cn-1 and J _cn closer to the temperature difference ΔT of the heat source, as shown in FIG. 11 and the like, the high-temperature side joint surfaces J _h1 , J _h2 , J _{h3, ·····, J hn-1} , J hn large heat sink portion of the heating fins _{5 j-1, 5 j,} 5 j + 1 equipped with the volume of the large-capacity provided on the low temperature side bonding surface J _c1 , J _c2 , J _c3 ,..., J _cn-1 , J _cn enhance the cooling effect by bringing the cooling fins 6 _j-1 , 6 _j , 6 _{j + 1} closer to the pn junction surface. Yes.

  Since the thermoelectric conversion system according to the second embodiment uses a metal thermoelectric conversion element, unlike the semiconductor thermoelectric conversion element, the Seebeck coefficient fluctuates very little due to a small amount of impurities. Therefore, ordinary steel and steel scrap can be used as the p-type conductor element. Further, the Fe—Al alloy as the n-type conductor element can be alloyed using aluminum scrap containing iron. Further, even if aluminum oxide inclusions produced during melting are present in the alloy, the influence on the thermoelectric properties is hardly recognized.

  In the thermoelectric conversion system according to the second embodiment, there is no auxiliary power source for operation and no mechanical drive unit, and the system configuration is composed of only a series unit (thermoelectric panel), a low-temperature heat source, and a water electrolyzer as materials. Therefore, it is possible to generate hydrogen and oxygen continuously in a steady state, and management is easy.

The thermoelectric conversion system according to the second embodiment has a large number of pn junction surfaces ( _Jh1 , _Jh2 , _Jh3 ,..., _Jhn-1 , _Jhn ; _Jc1 , J _c2 , J _c3 ,..., J _cn-1 , J _cn ), if there are voids or defects at the joint interface, the cause of energy loss due to the increase in resistance R _G between the thermoelectric panel terminals It becomes. Therefore, the bonding interface is formed by a melt diffusion bonding method.

The thermoelectric panel used for the thermoelectric conversion system according to the second embodiment can be manufactured by the following method. Note that the thermoelectric panel manufacturing method described below is merely an example, and it is needless to say that the thermoelectric panel can be realized by various other manufacturing methods including this modification example:
(A) First, an iron container forming the basic structure of the thermoelectric conversion element unit is produced by welding. That is, FIG. 12 (a), the terminal portions 1 _j walled made of iron, the terminal portion 1 _j and the first L-shaped structure walls connected iron orthogonally to configure Jo of the heat-conducting portion 1 _j, the second L-shaped structure with respect to the heat-conducting portion 1 _j from the first L-shaped structure is connected to a bending direction in the direction opposite the heat-conducting portion 1 _j a first bonding portion 1 _j of iron constituting the iron of the side wall portion 1 _j extending parallel to the heat-conducting portion from the first bonding portion 1 _j spaced from the heat conductive portion 1 _j, thermal conductivity A box-shaped container including a second joint forming portion 1 _{j + 1} made of iron connected to the portion 1 _j and the side wall portion 1 _j via the heat-resistant insulators 71 _j and 72 _j is produced by welding. . For example, the heat conducting portion 1 _j and the first joint forming portion 1 _j are connected by the build-up welding 81 _j , and the first joint forming portion 1 _j and the side wall portion 1 _j are connected by the build-up welding 82 _j . To do. The first joint forming portion 1 _j is configured with a heat radiating fin 5 _j , and the second joint forming portion 1 _{j + 1} is configured with a cooling fin 6 _j . Furthermore, as shown in FIG. 12 (b), the bottoms of the heat conducting part 1 _j , the first joint forming part 1 _j and the side wall part 1 _j are connected to the bottom plate 9 _j by welding. However, as shown in FIG. 12B, the bottom of the second bonding formation 1 _{j + 1} portion and the bottom plate 9 _j are connected via a heat-resistant insulator.

(B) Next, leaving the surfaces of the first junction forming portion 1 _j and the second junction forming portion 1 _{j + 1} , a heat resistant electrical insulator such as alumina (Al ₂ O _{3) is} formed on the inner surface of the iron container. ) Cement is applied as insulating films _4j-1 , _4j , _{4j + 1} .

  (C) Thereafter, as shown in FIG. 12A, a predetermined molten Fe—Al alloy (Fe—Al molten metal) 6 is poured (cast) into the container.

(D) When the Fe—Al molten metal 6 is solidified, as shown in FIGS. 12B and 12C, the element-shaped iron container becomes a mold, and the Fe—Al alloy 2 _j is cast as an n-type conductor element. (The composition of Al is 6 to 15% by weight, preferably 7 to 12% by weight.) At that time, the molten Fe—Al alloy is brought into contact with the joint surface where the iron is exposed, and melt diffusion bonding is performed, so that the interface between the first junction forming portion that becomes the p-type conductor element and the n-type conductor element is formed. In addition, the first pn junction is formed at the interface between the second junction forming portion that becomes the p-type conductor element and the n-type conductor element. At this time, aluminum diffuses and penetrates to the inside of several hundreds μm of the solid iron surface of the first and second joint forming portions, and in the microstructure after solidification, iron and Fe—Al alloy are ideally joined through the diffusion layer. Is done. That is, as shown in FIG. 13, this diffusion zone corresponding to the pn transition layer has a minute width of several hundreds μm, and the temperature change within that range is very slight. Has little effect on the electromotive force.

(E) The overall performance as a series unit (thermoelectric panel) of the thermoelectric conversion system according to the second embodiment is the same as that of the individual thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,. _n-1 and 51 _n are determined by the additivity of the thermoelectric characteristics indicated by _n . Therefore, when the thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n are completed, the individual thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ , ..., 51 _n−1 , 51 _n are accurately measured to confirm that they are theoretical values.

(F) Next, the thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n are welded in series or in parallel while confirming the additivity of the thermoelectric characteristics by actual measurement. To do. That is, the terminal portion (not shown) at the next stage and the second joint forming portion 1 _{j + 2} are joined using, for example, the welding surface 6 _{j + 1} in FIG. A series unit (thermoelectric panel) composed of an alternating series connection structure of a plurality of p-type conductor elements and a plurality of n-type conductor elements is completed by sequentially repeating this welding step. In FIG. 11, the next-stage terminal portion 1 _j and the second joint forming portion 1 _j are joined by the weld portion 83 _j , and the next-stage terminal portion 1 _{j + 1} and the second joint forming portion 1 _{j + 1} are joined. Are joined at the weld _{83j + 1} . As a result, as shown in FIG. 14, the thermoelectric conversion element units 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n are welded points 83 _j−2 , 83 _j−1. , 83 _j , 83 _{j + 1} , 83 _{j + 2} ,... Are joined by welding to complete the thermoelectric panel.

(Other embodiments)
As described above, the present invention has been described according to the first and second embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is a schematic diagram explaining the principle of thermoelectric conversion. It is a mimetic diagram (conceptual diagram) explaining a thermoelectric conversion system concerning a 1st embodiment of the present invention. It is sectional drawing which shows an example of the specific structure of the thermoelectric panel (series unit) used for the thermoelectric conversion system which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows an example of the structure of the low temperature side insulating film and high temperature side insulating film which are used for the thermoelectric panel (series unit) shown in FIG. It is process drawing for demonstrating the manufacturing method of the thermoelectric panel (series unit) used for the thermoelectric conversion system which concerns on the 1st Embodiment of this invention. It is a top view for demonstrating the manufacturing method of a thermoelectric panel (series unit) in case there are many serial couplings of a thermoelectric conversion element unit. It is a bird's-eye view which shows the state bent at the bending position following the process of FIG. It is typical sectional drawing explaining the state which has arrange | positioned the thermoelectric panel in a wind tunnel, and sent the hot air and the cold wind to the high temperature side channel and the low temperature side channel, respectively. It is a schematic diagram explaining the structure in the case of electrolyzing water using the thermoelectric conversion system which concerns on the 1st Embodiment of this invention. It is a circuit diagram at the time of setting it as the n * m matrix-shaped thermoelectric panel which connected the serial unit of the serial coupling number n to m pieces. It is a bird's-eye view which shows an example of the specific structure of the thermoelectric panel (series unit) used for the thermoelectric conversion system which concerns on the 2nd Embodiment of this invention, and is the three thermoelectric conversion element units in the serial unit of the serial connection number n. Shows the connected state. It is a typical bird's-eye view. FIG. 14 is a top view showing a state in which seven thermoelectric conversion element units among the series units having the number n of series couplings are connected. It is process drawing for demonstrating the manufacturing method of the thermoelectric conversion element unit used for the thermoelectric conversion system which concerns on the 2nd Embodiment of this invention. It is a figure explaining the concentration distribution of Al of the pn junction part of the thermoelectric conversion element unit which concerns on the 2nd Embodiment of this invention. It is a top view which shows an example of the specific structure of the thermoelectric panel (series unit) used for the thermoelectric conversion system which concerns on the 2nd Embodiment of this invention, and is 7 thermoelectric conversion elements in the series unit of the serial coupling number n Indicates that the unit is connected.

Explanation of symbols

J _c1 , J _c2 , J _c3 ,..., J _cn-1 ... low temperature side joint surface J _h1 , J _h2 , J _h3 , ..., J _hn-1 , J _hn ... high temperature side joint Surface L ... Distance between joints _Pj-1 , _Pj , _{Pj + 1} ... Heat of reflux W ... Output _RC ... Resistance between water electrolyzer terminals _RG ... Resistance between thermoelectric panel terminals R ... Load _RL ... Resistance value S _n ... Cross sectional area S _p ... Cross sectional area TC ... Temperature Th ... Heat source temperature V _C ... Water electrolytic cell terminal voltage V _G ... Open circuit voltage (DC power supply)
V ... Electromotive force (open voltage)
e ... electromotive force i ... current 1 ₁ , 1 ₂ , 1 ₃ , ..., 1 _n-1 , 1 _n ... p-type conductor elements 2 ₁ , 2 ₂ , 2 ₃ , ..., 2 _n-1 , 2 _n ... n-type conductor element (Fe-Al alloy)
3 _c1 , 3 _c2 , 3 _c3 ,..., 3 _cn-1 , 3 _cn ... low temperature side insulating film 3 _h1 , 3 _h2 , ..., 3 _hn-1 ... high temperature side insulating film 4 _{j -1} , 4 _j , 4 _{j + 1} ... insulating films 5 _j-1 , 5 _j , 5 _{j + 1} ... heating fins 6 _j-1 , 6 _j , 6 _{j + 1} ... cooling fins 6 ... Fe-Al molten metal 12a , 12b, 12c, ... aluminum foil 31 ... high temperature side channels 32 ... low-temperature side channel 35 ... top wall 36 ... inner wall 37 ... bottom wall 41 ... water electrolyzer 42 ... anode 43 ... cathode 53 ... thermoelectric panel 301j ... insulating film 301 _j , 302 _j , 303 _j , 304 _j , 305 _j , 301 _{j + 1} , 302 _{j + 1} , 303 _{j + 1} , 304 _{j + 1} , 305 _{j + 1} , 306 _{j + 1} ; 301 _{j + 2} , 302 _{j + 2} , 303 _{j + 2} , 304 _{j + 2} , 305 _{j + 2} , 306 _{j + 2} ... insulating films 51 ₁ , 51 ₂ , 51 ₃ ,..., 51 _n−1 , 51 _n . Transformation element Unit

Claims (10)

A plurality of p-type conductor elements made of iron and a plurality of n-type conductor elements made of iron / aluminum alloy are alternately arranged in a bellows fold structure, and a first p is formed at each of the plurality of peaks of the bellows fold structure. A plurality of p-type conductor elements and a plurality of n-type conductors are formed by forming a n-junction and connecting the plurality of valley portions of the bellows fold structure to form a second pn junction. A series unit having an alternating series connection structure with an element, giving different temperatures to the first and second pn junctions, and obtaining an electromotive force due to the Seebeck effect;
A thermoelectric conversion system comprising: a load directly connected between an anode terminal and a cathode terminal of the series unit.   The thermoelectric conversion system according to claim 1, wherein the series units are connected in parallel, thereby reducing the overall impedance and adjusting the impedance with the load. Directly connecting the anode terminal to the anode plate disposed in the water electrolyzer;
Directly connecting the cathode terminal to a cathode plate disposed in the water electrolyzer;
3. The thermoelectric conversion system according to claim 1, wherein water is electrolyzed using the resistance of water between the anode plate and the cathode plate as the load.   The thermoelectric conversion system according to any one of claims 1 to 3, wherein an insulating film is disposed between the alternately arranged p-type conductor elements and n-type conductor elements. .   The alternating series connection structure includes a plurality of p-type conductor elements having a flat strip shape, and a plurality of n-type conductor elements having the same width as the p-type conductor element and bent in an S shape. The thermoelectric conversion system according to any one of claims 1 to 4, wherein the thermoelectric conversion system is alternately connected to each other. The p-type conductor element includes a wall-shaped terminal portion, a wall-shaped heat conduction portion connected to the terminal portion in an orthogonal direction so as to form a first L-shaped structure, and a heat conduction portion On the other hand, the first L-shaped structure is connected in a direction that is bent in the opposite direction, and includes a first junction forming portion that forms a second L-shaped structure with the heat conducting portion,
The n-type conductor element has a columnar shape in which one end forms the first pn junction with the junction formation portion and extends parallel to the heat conduction portion,
The other end of the n-type conductor element is connected to a second junction forming portion made of the p-type conductor element joined to a terminal portion of the next-stage p-type conductor element and the second pn junction. ,
The thermoelectric conversion system according to any one of claims 1 to 4, wherein the alternating series connection structure is configured thereby.   The thermoelectric conversion system according to claim 6, further comprising a heat radiating fin in the first joint forming portion and a cooling fin in the second joint forming portion.   The thermoelectric conversion system according to claim 6 or 7, wherein the terminal part of the next stage and the second joint forming part are joined by welding. A wall-shaped terminal portion made of iron, a wall-shaped heat conduction portion made of iron and connected to the terminal portion in an orthogonal direction so as to form a first L-shaped structure, and the first heat conduction portion with respect to the heat conduction portion. The iron first joint forming portion that is connected in a direction that is bent in the opposite direction to the L-shaped structure and constitutes the second L-shaped structure with the heat conducting portion, and is separated from the heat conducting portion and An iron side wall extending parallel to the heat conducting part from the first joint forming part, and an iron second joint forming part connected to the heat conducting part and the side wall part via a heat resistant insulator, respectively. And a bottom plate that is in contact with the heat conduction part, the first joint formation part, and the side wall part, and is connected to the bottom part of the second joint formation part via a heat-resistant insulator. A process of preparing
Painting a heat-resistant electrical insulator on the inner surface of the box-shaped container other than the first and second joint forming parts;
The n-type conductor element is formed by casting molten iron / aluminum alloy into the container, and the p-type conductor element is formed by melting diffusion bonding and the n-type conductor element. Forming a first pn junction at the interface between the second junction forming portion and the n-type conductor element, and forming a second pn junction at the interface between the second junction forming portion and the n-type conductor element. The manufacturing method of the thermoelectric panel for thermoelectric conversion systems characterized by including this. Further comprising the step of joining the terminal portion of the next stage and the second joint forming portion by welding,
10. The thermoelectric conversion system according to claim 9, wherein an alternating series connection structure of a plurality of p-type conductor elements and a plurality of n-type conductor elements is formed by sequentially repeating the step of joining by welding. A method for manufacturing a thermoelectric panel.

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