JP5611739B2 - Thermoelectric power generation system - Google Patents

Description

  Embodiments of the present invention relate to a thermoelectric power generation system that directly converts heat into electricity.

  One of the recent energy saving technologies is a method of recovering heat generated in equipment and industrial plants using a thermoelectric conversion module. For example, a plurality of thermoelectric conversion modules are installed between high-temperature pipes and low-temperature pipes, and high-temperature water generated in equipment and industrial plants is allowed to flow through the high-temperature pipes. The power generation is performed by the temperature difference.

  The conventional configuration employs a structure in which a rectangular parallelepiped chamber having a flat portion on which the thermoelectric conversion module can be easily installed is attached to the pipe in order to transmit heat from the pipe serving as the heat source to the thermoelectric conversion module.

JP 2006-210568 A JP 2008-98403 A JP 2009-247050 A

  However, the chamber that conducts the heat from the pipe that is the heat source to the thermoelectric conversion module has a rectangular parallelepiped structure. Therefore, if the heat medium from the pipe flows directly, the chamber structure needs to be strengthened in order to create a pressure-resistant structure. There is. For this reason, for example, when the thickness of the structure is increased, there are problems that heat conduction is reduced, cost is increased, and weight is increased.

  In view of the above circumstances, an object of an embodiment of the present invention is to provide a thermoelectric power generation system that can use a pipe of an existing heat source without installing a chamber in a flow path of a heat medium.

The aspect for achieving the above object is a polyhedral container that is attached so as to surround an outer periphery of a pipe that is an existing heat source part through which a heat source fluid flows, and has a plane on at least a part of the outer surface,
And the thermoelectric conversion module attached to the plane of the container, is filled in the container in contact with the pipe, the heat from the heat source fluid flowing through the pipe provided with a heat transfer medium for transferring to the thermoelectric conversion module The container has a split mold structure that is divided into two or more parts, and after the pipe that is the existing heat source part is positioned on the central shaft portion and the split mold is bonded together, the inside of the container is filled with the heat transfer medium. it is characterized in that it is that structure.

  The present invention uses the piping of the heat source section as it is in the thermoelectric power generation system, and does not perform chamber installation in the flow path of the heat medium by attaching the thermoelectric power generation system. The heat conduction to the thermoelectric conversion module is performed using a heat transfer medium. That is, heat from the pipe of the heat source part is conducted to the heat transfer medium, and heat is supplied to the thermoelectric conversion module by heat conduction from the heat transfer medium.

It is a block diagram which shows the external appearance of the thermoelectric power generation system of embodiment, (A) is a front view, (B) is a side view. It is a block diagram which shows typically the internal cross section of the thermoelectric power generation system of embodiment, (A) is a front view, (B) is a side view. It is a block diagram which shows typically the internal cross section filled with the heat transfer medium in the thermoelectric power generation system of embodiment, (A) is a front view, (B) is a side view. Explanatory drawing which shows the structure of the thermoelectric conversion module used with the thermoelectric power generation system of embodiment. The characteristic view which shows the temperature dependence of the performance of the thermoelectric conversion element used for a thermoelectric conversion module. It is a block diagram which shows the other example of embodiment, (A) is a front view, (B) is a side view. It is a block diagram which shows the further another example of embodiment, (A) is a front view, (B) is a side view. The block diagram which shows the further another example of embodiment. The block diagram which shows the further another example of embodiment.

<First Embodiment>
FIG. 1 is a configuration diagram illustrating an appearance of a thermoelectric power generation system according to the embodiment, FIG. 2 is a configuration diagram schematically illustrating an internal cross section of the thermoelectric power generation system according to the embodiment, and FIG. 3 is a thermoelectric power generation system according to the embodiment. It is a block diagram which shows typically the internal cross section filled with the heat transfer medium.

  As shown in each figure, the thermoelectric power generation system 1 is attached to a rectangular parallelepiped container 5 attached so as to surround the outer periphery of a pipe 3 through which a heat source fluid flows, and an upper plane 5a and a lower plane 5b of the container 5. The thermoelectric conversion module 7 is provided. Note that the number of thermoelectric conversion modules 7 installed in the container 5 is four in the present embodiment. The number of installation is also limited by the size of the container 5, but is appropriately selected according to the desired power generation amount.

  The container 5 is filled with a heat transfer medium 9 that transmits heat from the heat source fluid flowing through the pipe 3 to the thermoelectric conversion module 7. As the heat transfer medium 9, any of water, oil, silicon, or ionic liquid is suitable.

  The container 5 has a split-type structure composed of an upper container 5c and a lower container 5d so that the existing pipe 3 can be installed without improvement, and the pipe 3 is positioned on the central axis portion. The upper container 5c and the lower container 5d are bonded to each other at the joint 11 using welding or an adhesive. The material constituting the container is preferably a metal having good thermal conductivity and strong corrosion resistance, and is selected from aluminum, copper, iron, stainless steel and the like.

  As long as the shape of the container 5 has a flat surface to which the thermoelectric conversion module 7 is attached, such as a rectangular parallelepiped, a polyhedron having a hexagonal cross section, an octagonal cross section, etc., or a structure having a flat surface in a part of a cylinder. Shape is conceivable.

  Further, the split mold is not limited to two divisions, but can be divided into a plurality of divisions such as three divisions, four divisions, etc. according to the shape and installation location of the piping.

《Thermoelectric conversion module》
The thermoelectric conversion module 7 uses the Seebeck effect to convert a temperature difference into an electromotive force. As shown in FIG. 4, the p-type and n-type thermoelectric conversion materials 7p and 7n are formed by a pair of insulating plates 7i. It has a sandwiched structure. The internal structure of the thermoelectric conversion module 7 is such that p-type thermoelectric conversion materials 7p and n-type thermoelectric conversion materials 7n are alternately arranged, and these are electrically connected by a solder material 7s. In this embodiment, a bismuth-tellurium (Bi-Te) compound is used as the thermoelectric conversion material. Below, the outline | summary of the performance of the thermoelectric conversion material used for the thermoelectric conversion module 7 is demonstrated.

  The figure of merit Z of the thermoelectric conversion material is expressed by the following formula (1).

Z = S × (σ / κ) (1)
Where S is the Seebeck coefficient indicating the thermoelectromotive force per 1 ° C., σ is the electrical conductivity, and κ is the thermal conductivity.

  As can be seen from the equation (1), the figure of merit Z of the thermoelectric conversion material improves as the Seebeck coefficient S and the electrical conductivity σ increase and as the thermal conductivity κ decreases.

  FIG. 5 shows the performance of various thermoelectric conversion materials with the horizontal axis representing temperature (° C.) and the vertical axis representing the dimensionless figure of merit ZT of the thermoelectric conversion material. The dimensionless figure of merit ZT on the vertical axis is obtained by multiplying the figure of merit Z of the thermoelectric conversion material by the absolute temperature T. In the figure, characteristic line A is silicon-germanium (Si-Ge) material, characteristic line B is lanthanum-tellurium (La-Te) material, characteristic line C is lead-tin (Pb-Sn) material and tellurium -Selenium (Te-Se) -based material and characteristic line D indicate bismuth-tellurium (Bi-Te) -based material, respectively. As is clear from FIG. 5, silicon-germanium (Si—Ge) and lanthanum-tellurium (La-Te) materials are excellent in thermoelectric conversion performance in the high temperature range of 900 ° C. or higher, and an intermediate temperature range of 400 to 600 ° C. In this case, lead-tellurium (Pb-Te) -based material is excellent in thermoelectric conversion performance, and bismuth-tellurium (Bi-Te) -based material is excellent in thermoelectric conversion performance in a low temperature range of 150 ° C. The thermoelectric conversion module 7 used in the present embodiment aims to recover the thermal energy of a heat medium such as exhaust gas discarded at a low temperature of 150 ° C. or lower, and therefore, bismuth-tellurium ( Bi-Te) materials are most suitable.

  On the other hand, as shown in FIGS. 1, 2, and 3, many radiating fins 13 are provided on the other side of the thermoelectric conversion module 7 that is different from the surface that contacts the container 5. Power generation efficiency is improved by cooling the other surface side of the thermoelectric conversion module 7 with the heat radiation fins 13.

  2 and 3 show the inside of the thermoelectric power generation system 1 shown in FIG. For the purpose of efficiently transferring the heat from the heat transfer medium 9 to the container 5 and the thermoelectric conversion module 7, many pleated fins 15 are provided on the inner surface of the container 5 in contact with the heat transfer medium 9. The surface area of the inner surface of the container 5 is expanded by the pleated fins 15, heat conduction to the container 5 is increased, and the amount of power generation in the thermoelectric conversion module 7 can be increased.

  FIG. 3 shows a state in which the heat transfer medium 9 is filled in the container 5 shown in FIG. In FIG. 3, the inlet of the heat transfer medium 9 is omitted. Further, in consideration of volume expansion due to high temperature of the heat transfer medium 9, the heat transfer medium 9 is not fully filled in the container 5 (full tank state). The filling amount of the heat transfer medium 9 is determined by the physical properties of the heat transfer medium used, the temperature of the heat medium, and the like.

  As shown in FIGS. 2 and 3, in the thermoelectric power generation system 1, at least the inner surface 19 of the container 5 in contact with the heat transfer medium 9 is subjected to corrosion resistance treatment. When the inner surface 19 where the heat transfer medium 9 is in contact with the container 5 is corroded, the heat conduction on the corroded surface is reduced, and the amount of power generated from the thermoelectric conversion module 7 is reduced. When an ionic liquid is used for the heat transfer medium 9, it is desirable that an alloy of zinc and magnesium is applied at least to the corrosion resistance treatment of the container surface in contact with the heat transfer medium 9. In addition to the container inner surface 19 in contact with the heat transfer medium 9, the corrosion resistance treatment may be performed by applying an alloy of zinc and magnesium on the pipe surface 17 in contact with the heat transfer medium 9 of the pipe 3 and the surface of the fin 15. .

  In the above configuration, the heat of the heat source medium flowing through the pipe 3 moves from the pipe 3 to the heat transfer medium 9, from the heat transfer medium 9 to the container 5, and from the container 5 to the thermoelectric conversion module 7. Cooling fins 13 are attached to the thermoelectric conversion module 7, and heat from the pipe 3 is diffused into the atmosphere through the cooling fins 13. When heat is transmitted to the thermoelectric conversion module 7, a part of the heat is converted into electricity. Thus, in this embodiment, the container 5 which comprises the thermoelectric power generation system 1 is attached to the piping 3, It is an existing heat source part, without performing chamber installation to the flow path of the heat source fluid like the past. By using the pipe 3 as it is, efficient thermoelectric power generation becomes possible.

<Second Embodiment>
6 employs a water cooling structure in which dedicated cooling pipes 21 and 22 having a rectangular parallelepiped shape are used instead of the cooling fins 13 of the thermoelectric conversion module of FIG. The low temperature side of the thermoelectric conversion module 7 is attached to the flat portions of the cooling pipes 21 and 22, and the low temperature side of the thermoelectric conversion module 7 is cooled by the cooling water flowing through the cooling pipes 21 and 22.

  According to this configuration, since the cooling water is circulated through the cooling pipes 21 and 22, the temperature difference between the pipe 3 and the cooling pipes 21 and 22 is larger than the example of cooling by the cooling fins 13, and the thermoelectric There is an effect that the conversion module 7 has a temperature difference, and the amount of power generated from the thermoelectric conversion module 7 increases.

<Third Embodiment>
FIG. 7 shows a third embodiment and shows an example in which cooling pipes 23 and 24 are installed in parallel with the pipe 3 through which the heat source fluid flows. In this case, rectangular parallelepiped containers 25 and 26 are attached so as to surround the outer periphery of the cooling pipes 23 and 24 through which the cooling water flows, and the containers 25 and 26 are filled with the heat transfer media 27 and 28. The containers 25 and 26 have a two-part split structure composed of an upper container and a lower container, as in the case of the container 5, and the pipes 23 and 24 are located in the central axis portion so that the upper container and the lower container are located. Are bonded together at the joints 29 and 30 using welding or an adhesive. The material constituting the containers 25 and 26 is preferably a metal that has good thermal conductivity and is resistant to corrosion, and is similar to the container 5 in that it is selected from aluminum, copper, iron, stainless steel, and the like. As long as the shape of the container 25 has a flat surface to which the thermoelectric conversion module 7 is attached, such as a rectangular parallelepiped, a polyhedron such as a hexagonal cross section, an octagonal cross section, etc. Shape is conceivable. Furthermore, the heat transfer media 27 and 28 are preferably water, oil, silicon, or an ionic liquid, like the heat transfer media 9.

  According to this configuration, by using the cooling pipes 23 and 24 through which the cooling water flows, the temperature difference between the pipe 3 and the cooling pipes 23 and 24 increases, and the thermoelectric conversion module 7 has a temperature difference. There is an effect that the amount of power generation from the thermoelectric conversion module 7 is increased. Further, the existing cooling pipes 23 and 24 can be used as they are without installing a dedicated cooling pipe.

<Fourth Embodiment>
In the thermoelectric power generation system 1, it is preferable to use the container 5 filled with the heat transfer media 9, 27, 28 with a heat storage material. A latent heat storage material is used as the heat storage material. Even if the temperature of the heat source fluid flowing through the pipe 3 or the temperature of the cooling water flowing through the cooling pipes 23 and 24 changes by putting the latent heat storage material in the heat transfer medium 9, 27, 28, the temperature in the heat transfer medium 9 Can be maintained above the phase change temperature of the latent heat storage material, and the amount of power generation can be stably obtained from the thermoelectric conversion module 7.

《Heat storage material》
The heat storage material is selected according to the temperature of the heat source. In the case where the heat source temperature is in the range of 80 to 170 ° C., candidate materials include mannitol, Mg (NO ₃ ) ₂ .2H ₂ O, erythritol, MgCl ₂ .6H ₂ O, Al ₂ (SO ₄ ) ₃ · 16H ₂ O. , KAl (SO ₄ ) ₂ · 12H ₂ O, Mg (NO ₃ ) ₂ · 6H ₂ O, Al (NO ₃ ) ₃ · 8H ₂ O, Al ₂ (SO ₄ ) ₃ · 12H ₂ O, AlK (SO ₄ ) ₂ · 12H ₂ O, Ba (OH) ₂ · 8H ₂ O.

If the heat source temperature is 80 to 100 ° C., water is used as the heat transfer medium 9, 27, 28, and a combination of KAl (SO ₄ ) 2 · 12H ₂ O or Mg (NO ₃ ) 2 · 6H ₂ O is suitable for the heat storage material. It is.

When the heat source temperature is 100 to 120 ° C., a combination of silicon as the heat transfer medium 9, 27, 28 and erythritol as the heat storage material is suitable. Table 1 shows the relationship between the heat storage material and the phase change temperature.

<Fifth Embodiment>
In the thermoelectric power generation system 1, it is preferable to use the container 5 filled with the heat transfer media 9, 27, and 28 with carbon. Carbon is in the form of nanocarbon. By filling carbon in the heat transfer media 9, 27, and 28, the thermal conductivity of the heat transfer media 9 containing carbon can be increased. By improving the heat conduction in the heat transfer media 9, 27, and 28, the heat from the pipes 3, 23, and 24 can be efficiently conducted to the thermoelectric conversion module 7, and power can be stably generated from the thermoelectric conversion module 7. The quantity can be obtained.

<Other embodiments>
<< Modification 1 >>
8 and 9 show the installation of the thermoelectric power generation system 1 on a bent pipe. In FIG. 8, the bent portion of the pipe 3A bent in a U shape is submerged in a container 51 in which the heat transfer medium 9 is stored. Moreover, the example of FIG. 9 shows the example which attached the container 53 to the bending part of horizontal piping 3B. In either case, the thermoelectric power generation system 1 is attached to the existing pipes 3A and 3B.

<< Modification 2 >>
Although not shown in the figure, the generated electricity is a direct current. Therefore, the thermoelectric power generation system is combined with an inverter, a controller, a power conditioner, a battery and a capacitor to perform direct current to alternating current conversion, and the obtained electricity is used. Depending on the application, the obtained direct current electricity may be used as it is.

<< Modification 3 >>
Moreover, the thermoelectric power generation system 1 according to the embodiment can be used to produce electricity from waste heat generated in a garbage incineration plant or a cleaning factory and use it as a power source for lighting or a ventilation fan. Specifically, the container 5 is attached to a high-temperature pipe through which waste heat water that has cooled the incinerator flows. Moreover, it comprises so that the container 5 may be attached to piping which uses the waste heat water after implementing steam power generation by the waste heat recovery from an incinerator as a high-temperature heat source fluid. Electric power is generated by the thermoelectric conversion module 7 using the cooling water as a cold medium. Alternatively, power generation is performed by heat radiation using fins instead of cooling pipes.

<< Modification 4 >>
Moreover, electricity can be manufactured from the waste heat generated in an oil refinery using the thermoelectric power generation system 1 according to the embodiment, and can be used as a power source for in-house lighting or a ventilation fan. Specifically, power generation is performed using the exhaust heat generated when the refined oil fractionated by refining crude oil is returned to room temperature as a high-temperature medium and cooling water as a cold medium. Alternatively, power generation is performed by heat radiation using fins instead of the cooling medium piping.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Thermoelectric power generation system 3 Piping 3A, 3B U-shaped piping 5, 25, 26, 51, 53 Container 7 Thermoelectric conversion module 9 Heat transfer medium 11 Adhesive member 13 Radiation fin 15 Fin 17 Corrosion coating part (piping surface)
19 Corrosion coating part (inner side of container)
21, 22, 23, 24 Cooling water piping 25, 26 Cooling water container 27, 28 Cooling heat transfer medium

Claims (9)

A polyhedral container that is attached to surround the outer periphery of the pipe , which is an existing heat source part through which the heat source fluid flows, and has a flat surface at least in part of the outer surface;
A thermoelectric conversion module attached to the plane of the container;
A heat transfer medium filled in the container and in contact with the pipe to transfer heat from a heat source fluid flowing through the pipe to the thermoelectric conversion module ;
The container has a split mold structure that is divided into two or more parts. After the pipe, which is the existing heat source part, is positioned on the central shaft portion and the split mold is bonded together, the heat transfer medium is filled therein. A thermoelectric power generation system characterized by a structure . The thermoelectric power generation system according to claim 1 ,
The thermoelectric power generation system according to claim 1, wherein the material constituting the container is selected from at least aluminum, copper, iron, and stainless steel according to the material of the heat transfer medium . The thermoelectric power generation system according to claim 1 or 2 ,
A thermoelectric power generation system, wherein an inner surface of the container and a surface of the pipe in contact with the heat transfer medium are coated with corrosion . The thermoelectric power generation system according to any one of claims 1 to 3 ,
The thermoelectric power generation system according to claim 1 , wherein fins are provided on an inner surface side of the container facing the mounting surface of the thermoelectric conversion module . The thermoelectric power generation system according to any one of claims 1 to 4 ,
The thermoelectric conversion module is composed of a thermoelectric conversion material mainly composed of bismuth and tellurium . The thermoelectric power generation system according to any one of claims 1 to 5 ,
The thermoelectric power generation system , wherein the heat transfer medium is selected from a group including at least water, oil, silicon, and ionic liquid . The thermoelectric power generation system according to any one of claims 1 to 6 ,
A thermoelectric power generation system in which a heat storage material is mixed in a heat transfer medium . The thermoelectric power generation system according to any one of claims 1 to 7 ,
A thermoelectric power generation system, wherein carbon particles are mixed in the heat transfer medium . The thermoelectric power generation system according to any one of claims 1 to 8 ,
When the pipe is a high-temperature pipe, the thermoelectric power generation system is characterized in that the cold side of the thermoelectric conversion module is attached to the cold pipe through which a cooling medium flows .

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