JP2013048229A - Thermoelectric generator and thermoelectric power generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric generator which can obtain a large heat collection effect when it is applied to a heat source such as a hot steel material and can obtain a large amount of power per thermoelectric element module, and a thermoelectric power generation method using the thermoelectric generator.SOLUTION: The thermoelectric generator includes a heat receiving member 1 whose front face is opposed to a heat source and one or two or more thermoelectric element modules 2 joined to the rear of the heat receiving member 1 via a heat receiving surface 20. The heat receiving member 1 has an effective projection area [A1] which, with respect to a total heat receiving area [A2] of the heat receiving surface 20 of the thermoelectric element module 2, satisfies the relationship [A1]>[A2]. A thermoelectric power generation method uses this thermoelectric generator, and generates electric power from steel materials in a steel manufacturing process as its heat sources. Since a large heat collection effect is obtained by the heat receiving member 1, it is possible to obtain a large amount of power per thermoelectric element module 1.

Description

  The present invention relates to a thermoelectric generator suitable for power generation using steel (waste heat) as a heat source in a yard that stores high-temperature steel for a long time, such as a slab yard in a steel manufacturing process or a product yard after rolling, and this The present invention relates to a thermoelectric power generation method using the apparatus.

In recent years, for the purpose of preventing global warming, further energy saving is demanded in a production process that generates a large amount of CO ₂ such as a steel production process. One of the energy saving measures is waste heat recovery. Especially in mass production processes such as steel production, since a large amount of energy is wasted as waste heat, the energy saving effect obtained by waste heat recovery is very large.
Conventionally, as one of waste heat recovery methods, waste heat utilization thermoelectric power generation using a thermoelectric element is known. This thermoelectric power generation is a method of directly recovering electric power from a temperature difference using the Seebeck effect, and in recent years, part of the thermoelectric power generation has been put into practical use by improving the characteristics of thermoelectric elements.

  However, in the steel manufacturing field, for example, the application of thermoelectric power generation to waste heat recovery has not progressed sufficiently. The reason for this is that, in addition to the high cost of thermoelectric elements, it is difficult to use the waste heat of the steel manufacturing process as a stable heat source, making it impossible to optimally design thermoelectric elements, resulting in sufficient power generation efficiency and availability. It cannot be mentioned. If the power generation efficiency and operation rate of the thermoelectric element are not sufficient, the cost per unit power generation amount will increase as a result, and the application of thermoelectric power generation becomes extremely difficult in terms of cost effectiveness.

When considering waste heat recovery of high-temperature steel materials generated in the steel manufacturing process, waste heat cannot be used as a stable heat source. The main reason is that it is a batch process manufactured in units. Another factor that makes it difficult to apply thermoelectric power generation is placement restrictions due to many places exposed to dust and steam on the production line.
In order to solve the problems associated with the instability of the heat source described above, it is necessary to consider both an increase in the amount of power generation per thermoelectric element and stabilization of the power generation efficiency of the thermoelectric element. That is, the performance of the thermoelectric element can be maximized by devising the heat transfer member on the heat receiving side to increase the power generation amount of the thermoelectric element and keeping the power generation capacity high and stable.

Fins and the like are generally used as the heat transfer member in the thermal design, but the fin is usually a cooling member and is rarely used as a heat receiving member. Also in power generation by a thermoelectric element, as shown in Patent Documents 1 and 2, it is usually used as a cooling member on the low temperature side (cooling side) of the thermoelectric element.
On the other hand, some techniques using a heat receiving member on the high temperature side (heat receiving side) of the thermoelectric element are also seen. For example, Patent Documents 3 and 4 show a high-temperature side heat receiving member when thermoelectric cooling (Peltier cooling) is performed by a thermoelectric element. However, unlike thermoelectric power generation, thermoelectric cooling is a method of absorbing heat using externally supplied electric power, and the above Patent Documents 3 and 4 are designed to assume an endothermic action during thermoelectric cooling. .
Regarding thermoelectric power generation, several methods using a heat receiving member on the heat receiving side have been proposed. For example, Patent Documents 5 to 7 show heat receiving fins for increasing the contact area with the exhaust gas in the exhaust gas duct.

JP 2006-86210 A JP-A-5-302987 Japanese Patent Laid-Open No. 2005-180796 JP-A-7-218082 JP 2002-199762 A Japanese Patent Laid-Open No. 11-122960 JP 2006-214350 A

The heat-receiving fins shown in Patent Documents 5 to 7 have a structure that promotes heat transfer in the vertical direction with respect to the heat-receiving surface of the thermoelectric element, and heat reception from the exhaust gas duct is usually mainly convective heat transfer. A sufficient heat collecting effect can be obtained only by increasing the contact area with exhaust gas. However, the heat receiving fins shown in Patent Documents 5 to 7 cannot obtain a sufficient heat collecting effect when the heat receiving is mainly radiant heat transfer.
In addition, as described above, in the steel manufacturing process, the temperature change of the heat source (waste heat) itself is large, and depending on the state of the heat source, there is a region where heat is received only by radiant heat transfer. There are also areas where heat and convective heat transfer occur. In the prior art, the performance of the thermoelectric element cannot be maximized and stably in response to such a temperature change of the heat source.

  Accordingly, an object of the present invention is to provide a thermoelectric power generation device that can obtain a large heat collection effect when applied to a heat source such as a high-temperature steel material in a steel production process and can obtain a large amount of power generation per thermoelectric element module. It is in. Another object of the present invention is to provide a thermoelectric generator capable of selecting an optimum heat receiving form according to a temperature change of a heat source and the like and capable of maximizing and stably exhibiting the performance of a thermoelectric element. It is in. Furthermore, the other object of this invention is to provide the thermoelectric power generation method which uses the steel material of the steel manufacturing process using such a thermoelectric power generation apparatus as a heat source.

As a result of repeated studies to solve the above problems, the present inventors have arranged (i) a heat receiving member having an effective projected area larger than the heat receiving surface of the thermoelectric element module on the heat receiving side of the thermoelectric element module. A large heat collection effect can be obtained and a power generation amount larger than the area ratio increment can be obtained. (Ii) Furthermore, fins are provided on the front surface of the heat receiving member, and the apparatus can be moved forward and backward with respect to the heat source. By making it possible to adjust the distance (interval), it is possible to select the optimum heat receiving form according to the temperature change of the heat source, etc., and to maximize the performance of the thermoelectric element, and (iii) Therefore, the present inventors have found the fact that by using such a thermoelectric power generation apparatus, efficient thermoelectric power generation can be performed using a high temperature steel material in a steel manufacturing process as a heat source.
The present invention has been made on the basis of such findings and has the following gist.

[1] A heat receiving member (1) whose front surface is opposed to a heat source, and one or more thermoelectric element modules (2) joined to the back surface of the heat receiving member (1) via the heat receiving surface (20) side The effective projection in which the heat receiving member (1) satisfies [A1]> [A2] with respect to the total heat receiving area [A2] of the heat receiving surface (20) of one or more thermoelectric element modules (2). A thermoelectric power generation method using a thermoelectric power generation device having an area [A1] and generating power using a steel material in a steel manufacturing process as a heat source.
[2] The thermoelectric power generation method according to [1], wherein power generation is performed using a steel material having a surface temperature of 300 ° C. or higher as a heat source.

[3] The thermoelectric power generation method according to [1] or [2], wherein the thermoelectric power generator is capable of adjusting a distance to a heat source.
[4] The thermoelectric power generation method according to [3], wherein the power generation output by the thermoelectric power generation device is monitored, and the distance of the thermoelectric power generation device to the heat source is adjusted according to the monitored power generation output. .
[5] In the thermoelectric power generation method according to any one of [1] to [4], the thermoelectric power generator includes an effective projected area [A1] of the heat receiving member (1) and a heat receiving surface (20) of the thermoelectric element module (2). The total heat receiving area [A2] satisfies [A1] ≧ [A2] × 2.3.

[6] The thermoelectric power generation method according to any one of [1] to [5], wherein the heat receiving member (1) of the thermoelectric power generator has a fin (5) on the front side thereof.
[7] The thermoelectric power generation method according to any one of [1] to [6], wherein the thermoelectric power generation device includes a heat receiving member (1) that at least partially surrounds the heat source.
[8] The thermoelectric power generation method according to [7], wherein the thermoelectric power generation device includes a tunnel-shaped or dome-shaped heat receiving member (1) covering the heat source.
[9] In the thermoelectric power generation method according to any one of [1] to [8], the thermoelectric power generation device is characterized in that the front surface of the heat receiving member (1) is blackbody-treated.

[10] A heat receiving member (1) having a front surface facing the heat source, and one or more thermoelectric element modules (2) joined to the back surface of the heat receiving member (1) via the heat receiving surface (20) side. The heat receiving member (1) has an effective projection satisfying [A1]> [A2] with respect to the total heat receiving area [A2] of the heat receiving surface (20) of one or more thermoelectric element modules (2). A thermoelectric generator having an area [A1].
[11] The thermoelectric generator according to [10], wherein the distance to the heat source is adjustable.
[12] The thermoelectric power generator according to the above [11], comprising a device for monitoring the power generation output, wherein the distance to the heat source can be adjusted according to the power generation output monitored by the device. .

[13] In the thermoelectric generator of any one of [10] to [12] above, the total heat receiving area of the effective projected area [A1] of the heat receiving member (1) and the heat receiving surface (20) of the thermoelectric element module (2) [A2] satisfies [A1] ≧ [A2] × 2.3.
[14] In the thermoelectric generator according to any one of [10] to [13], the heat receiving surface (20) of the thermoelectric element module (2) is joined to the back surface of the heat receiving member (1) directly or via a sheet. A thermoelectric generator characterized by that.

[15] The thermoelectric generator according to any one of [10] to [14], wherein the heat receiving member (1) has a fin (5) on the front side thereof.
[16] The thermoelectric generator according to any one of [10] to [15], further including a heat receiving member (1) that at least partially surrounds the heat source.
[17] The thermoelectric generator according to [16], further comprising a tunnel-shaped or dome-shaped heat receiving member (1) that covers a heat source.
[18] The thermoelectric power generator according to any one of [10] to [17], wherein the front surface of the heat receiving member (1) is black-body treated.

Since the thermoelectric power generation device of the present invention can obtain a large heat collecting effect by the heat receiving member (1), the power generation amount per thermoelectric element module can be greatly increased as compared with the conventional device having no such member. Can do. For this reason, the equipment cost per unit power generation amount can be significantly reduced as compared with the conventional case.
In addition, in the apparatus in which the fin (5) is provided on the front surface of the heat receiving member (1) and can be moved back and forth with respect to the heat source, the distance from the heat source can be adjusted, so that the temperature of the heat source can be adjusted. The optimum heat receiving form can be selected, and the performance of the thermoelectric element can be maximized and stably exhibited.
In addition, the thermoelectric power generation method of the present invention can efficiently generate power by using waste heat of high-temperature steel materials in a steel manufacturing process that has hardly been subjected to sensible heat recovery. It can be used and energy efficiency in the integrated steelworks can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a plan view and FIG. 1A is a rear view schematically showing an embodiment of a thermoelectric generator of the present invention. Drawing for explaining energy balance during thermoelectric generation by thermoelectric elements Drawing showing the breakdown of energy balance during thermoelectric generation by thermoelectric elements FIG. 4A schematically shows another embodiment of the thermoelectric generator of the present invention, FIG. 4A is a plan view, and FIG. 4A is a rear view. Graph showing the relationship between temperature and dimensionless figure of merit ZT for various thermoelectric elements Explanatory drawing for demonstrating the optimal distance with a heat source about the thermoelectric generator of this invention which can advance / retreat with respect to a heat source FIG. 7A schematically shows another embodiment of the thermoelectric generator of the present invention, FIG. 7A is a plan view, and FIG. 7A is a rear view. FIG. 8A is a plan view and FIG. 8A is a rear view schematically showing another embodiment of the thermoelectric generator of the present invention. The front view which shows typically other embodiment of the thermoelectric generator of this invention FIG. 10A is a plan view and FIG. 10A is a rear view schematically showing an experimental apparatus used in the examples. The graph which shows the generated electric power P of the experimental apparatus of an example of the present invention in an example. The graph which shows the generated electric power P of the experimental apparatus of a comparative example in an Example

FIG. 1 schematically shows an embodiment of a thermoelectric generator according to the present invention. FIG. 1 (a) is a plan view and FIG. 1 (a) is a rear view. In the figure, 6 is a heat source (for example, high-temperature steel).
This thermoelectric generator has a heat receiving member 1 whose front face 10 faces the heat source 6, and a thermoelectric element module 2 joined to the rear face 11 of the heat receiving member 1 via the heat receiving face 20 side. [A1]> [A2] with respect to the heat receiving area [A2] of the heat receiving surface 20 of the thermoelectric element module 2 (however, when there are a plurality of thermoelectric element modules 2, the total heat receiving area [A2] of the heat receiving surface 20). ] Has an effective projection area A1.
Here, the effective projected area [A1] of the heat receiving member 1 is the projected area of the flat plate when the heat receiving member 1 is flat, and is expanded into a flat shape when the heat receiving member 1 is not flat. It refers to the projected area of the virtual flat plate.
In the present embodiment, one thermoelectric element module 2 is attached to one heat receiving member 1. However, as in the embodiment described later, two or more heat receiving members 1 are provided. It is good also as a structure where the thermoelectric element module 2 is attached.

The heat receiving member 1 of this embodiment is comprised with the metal board | plate material. The heat receiving member 1 is normally configured in a plate shape as in the present embodiment, but is not limited thereto. The heat receiving member 1 is made of, for example, one or more kinds of metals such as copper, copper alloy, aluminum, and aluminum alloy.
The heat receiving surface 20 of the thermoelectric element module 2 is joined to the back surface of the heat receiving member 1 directly or via a sheet in order to reduce the contact heat resistance with the heat receiving member 1. In the present embodiment, the heat receiving surface 20 of the thermoelectric element module 2 is the heat receiving member in consideration of the influence of the thermal deformation caused by the temperature difference between the heat receiving member 1 and the thermoelectric element module 2 and the generation of contact thermal resistance due to fine irregularities on the contact surface. 1 is joined to the back surface of the sheet 1 via a sheet 3 having high thermal conductivity. In general, since a member that generates a temperature difference is concerned about thermal deformation or generation of thermal stress, it is attached as a cushioning material via a sheet having high thermal conductivity as described above. Widely used. The sheet 3 having high thermal conductivity may be the one generally used.
The joining method of the heat receiving surface 20 of the thermoelectric element module 2 and the heat receiving member 1 is arbitrary, for example, a method using a fastening means such as a bolt, or a method using a sheet 3 having an adhesive layer on both sides.

  In general, a large heat receiving member (that is, a heat receiving member whose effective projected area [A1] is larger than the heat receiving area [A2] of the heat receiving surface 20) as the apparatus of the present invention has is used on the heat receiving side of the thermoelectric element module. Absent. One reason for this is that heat collection is a heat transfer to the opposite side of the heat release, so heat transfer in the heat transfer member is unlikely to occur, and it has been considered difficult to obtain the advantage of providing a large heat receiving member. Is mentioned. However, when heat is absorbed from the outside as in heat source cooling, since a heat collecting effect can be expected, it is usually used for thermoelectric cooling as in Patent Documents 3 and 4 mentioned above.

In the case where thermoelectric power generation is performed with respect to the conventional concept and the conventional technology as described above, the results of the study by the present inventors will be described. The energy balance at the time of thermoelectric power generation by the thermoelectric element is represented by the formulas shown in FIG. 2 and (1) to (3) below. T _h is the hot side temperature of the thermoelectric element in FIG. 2, T _c is the cold side temperature, T _h and according to the temperature difference ΔT of T _c, q _h and q _c in each hot side and cold side of the thermoelectric element heat transfer occurs, part of q _h is converted to electric power P. FIG. 3 shows a breakdown of the heat balance of the equations shown in the following (1) to (3). In equation (a) of (1) below, the first term is the movement of heat generated by power generation (Peltier heat absorption), the second term is Joule heat generation during power generation, and the third term is the effect of heat conduction by the thermoelectric element itself. Represents.

As described above, large thermal resistance higher performance thermoelectric element, that is, the thermal conductance K _e decreases, the effect of the third term in the above formula (a) (i.e. in Fig. 3 (i)) becomes small, Heat transfer is unlikely to occur. However, on the other hand, the thermoelectric power α _e is designed such that the higher the performance of the thermoelectric element, the larger the α _e, so the effect of Peltier endothermic which is the first term of the above formula (a) (that is, in FIG. 3). (Ii)) is large. The effect of this Peltier absorption is proportional to the respective upper temperature T _h of the current I and the thermoelectric elements as in the above formula (a). Since the generated current I is a linear function of the high-temperature side temperature T _h of the thermoelectric elements, the effect of the Peltier absorption increases in second order of T _h. That is, the greater the generated power, the greater the heat absorption effect, and the effect of promoting the heat absorption of the thermoelectric element heat receiving surface is increased, so that the heat collecting effect by the heat receiving member is expanded. Therefore, in a case where a high-performance thermoelectric element is used, not only thermoelectric cooling (Peltier cooling) but also thermoelectric power generation can be expected to have a heat collecting effect by the heat receiving member due to this Peltier heat absorption.

  As described above, the waste heat generated in the steel manufacturing process has a large temperature change, and the influence of radiant heat transfer is particularly large in a temperature range where the surface temperature of the heat source exceeds 500 ° C. In the case of radiant heat transfer, the amount of heat received varies depending on the effective projected area. Therefore, in the present invention, as shown in FIG. 1, [A1]> [ The heat receiving member 1 having an effective projected area [A1] that satisfies A2] is provided on the heat receiving side of the thermoelectric element module 2 to increase the amount of heat received.

In the device of the present invention, the effective projected area [A1] of the heat receiving member 1 and the heat receiving area [A2] of the heat receiving surface 20 of the thermoelectric element module 2 (when there are a plurality of thermoelectric element modules 2, the total heat receiving area of the heat receiving surface 20). The relationship [A2]) only needs to satisfy [A1]> [A2], but in order to obtain a large amount of power generation per thermoelectric element module, the effective projection of the heat receiving member 1 on the heat receiving area [A2]. It is preferable that the area [A1] is sufficiently large. Further, if the effective projected area [A1] of the heat receiving member 1 with respect to the heat receiving area [A2] is not sufficiently large, the heat collecting effect by the heat receiving member 1 is due to the influence of heat removal by a bolt or the like that fixes the heat receiving member 1. There is a possibility that it cannot be obtained sufficiently. From such a viewpoint, the effective projected area [A1] of the heat receiving member 1 and the heat receiving area [A2] of the heat receiving surface 20 of the thermoelectric element module 2 (if there are a plurality of thermoelectric element modules 2, the total of the heat receiving surfaces 20) The heat receiving area [A2]) preferably satisfies [A1] ≧ [A2] × 2.3.
When the heat receiving surface 20 of the heat receiving member 1 and the thermoelectric element module 2 is square or rectangular as shown in FIG. 1, for the same reason as described above, the length [X1] of one side of the heat receiving member 1 is It is preferably 1.5 times or more the length [X2] of one side of the heat receiving surface 20 of the thermoelectric element module 2.

The heat receiving member 1 may be provided with fins on the front side (heat receiving side), and a heat collecting effect by convective heat transfer is also obtained by the action of the fins. FIG. 4 schematically shows an embodiment of such a thermoelectric power generation apparatus. FIG. 4A is a plan view and FIG. 4A is a rear view.
The heat receiving member 1 is provided with fins 5 on the front side of a plate-like main body 4 (in this embodiment, a flat plate-like main body). The fin 5 is composed of a plurality of plates 50 protruding in parallel on the front surface of the plate-like main body 4. If only radiant heat transfer is considered, a predetermined effect can be obtained even with a flat heat receiving member 1 without fins as in the embodiment of FIG. However, as described above, the heat source temperature of waste heat in the steel manufacturing process changes, and heat transfer due to convective heat transfer is mainly performed as the surface temperature is lowered. Sometimes heat cannot be recovered. With respect to such a problem, by providing the fins 5 on the front surface of the heat receiving member 1 as in this embodiment, a heat collecting effect by convective heat transfer can be obtained. Further, when there are irregularities such as fins, an effect of improving the apparent emissivity (= absorption rate) can be obtained, which is also effective when considering radiant heat transfer. The shape and structure of the fin 5 are arbitrary, and the same effect can be obtained not only in a plate shape as shown in FIG. 4 but also in a square bar shape or a pin shape.

  The thermoelectric generator may be capable of advancing and retreating with respect to the heat source (approaching and separating by movement) so that the distance to the heat source can be adjusted. In general, a thermoelectric element has an appropriate temperature for maximizing its efficiency. The graph of FIG. 5 shows the temperature dependence of a dimensionless figure of merit ZT (Z: figure of merit) indicating the performance of the thermoelectric element. There are various types of thermoelectric elements from low temperature (about 100 ° C.) to high temperature (about 700 ° C.). As shown in FIG. 5, the dimensionless figure of merit ZT is a specific temperature range. The dimensionless figure of merit ZT decreases and the power generation efficiency of the thermoelectric element decreases outside this temperature range. Each thermoelectric element also has an upper limit of application temperature determined from the viewpoint of heat resistance. Therefore, if the thermoelectric generator can be moved back and forth with respect to the heat source (approachable / movable by movement) and the distance to the heat source can be adjusted, the power generation amount P calculated from the dimensionless figure of merit ZT is maximized. The device can be placed at a position. Further, since the generated power P can be monitored during power generation, the generated power P can be maximized by adjusting the distance to the heat source of the thermoelectric generator according to the actual value of the generated power P.

  Accordingly, a monitoring device for monitoring the power generation output of the thermoelectric power generation device and a mechanism (a movement mechanism of the thermoelectric power generation device) that can adjust the distance to the heat source are provided, and the heat source according to the power generation output monitored by the monitoring device is provided. It is preferable to adjust the distance of the thermoelectric generator. For example, the maximum power generation output (for example, 2.5 W in the case of a Bi-Te thermoelectric element) is set as the upper limit value or the target value, and the monitored power generation output is set to the upper limit value. You may make it adjust the distance of the thermoelectric generator with respect to a heat source so that it may not exceed or approach a target value. Moreover, when initializing the position of the thermoelectric generator for this adjustment, it is possible to adopt a method in which the thermoelectric generator is brought closer to the heat source while monitoring the generated power.

  In addition, by making the thermoelectric power generation device provided with fins 5 on the heat receiving member 1 as shown in FIG. 4 to be able to advance and retreat with respect to the heat source (approach and separation by movement), and to be able to adjust the distance to the heat source, The advantages of the thermoelectric generator can be maximized. That is, the basic heat receiving by the heat receiving member 1 is due to radiant heat transfer, but when the thermoelectric generator is close to the heat source, heat is also received by convective heat transfer, and the fin 5 receives heat by this convective heat transfer. It becomes an effective means. Therefore, when the heat receiving environment changes, such as when the heat source changes or the heat source temperature changes, the thermoelectric generator is moved forward and backward (approached or separated) from the heat source to adjust the distance between the heat source and the thermoelectric generator, The amount of heat received by each of radiant heat transfer and convective heat transfer can be positively controlled. Specifically, it is possible to select whether the heat is received only by radiant heat transfer or by radiant heat + convection heat transfer, and power generation is performed with the efficiency of the thermoelectric element always maximized. be able to.

With respect to the thermoelectric power generator of the present invention that can advance and retreat with respect to the heat source, the concept of adjusting the distance (distance) between the heat source when the heat source is high and low will be described with reference to FIG. When the surface temperature of the heat source (heat source material) is high (for example, 800 ° C.), the effect of radiant heat transfer is large, and the heat flux on the heat receiving surface is rather excessive in a thermoelectric element having a low heat resistance such as Bi-Te. Therefore, as shown in FIG. 6A, the interval between the thermoelectric generator (heat receiving member 1) and the heat source 6 is increased (interval d ₀ ), and the amount of heat received by radiant heat transfer is adjusted to maximize the generated power P. Plan. On the other hand, when the surface temperature of the heat source (heat source material) is low (for example, 300 ° C.), in order to use heat transfer by convective heat transfer, the thermoelectric generator (heat receiving member 1) and The interval between the heat source is narrowed (interval d ₁ ), and the generated power P is maximized by radiant heat transfer and convective heat transfer. By adjusting the distance from the heat source in this way, it is possible to stably obtain a high output voltage constantly with respect to the temperature change of the heat source.

  As described above, in the thermoelectric generator of the present invention, two or more thermoelectric element modules 2 may be attached to one heat receiving member 1, for example, considering the characteristics of the heat source in the steel manufacturing process. In many cases, such a structure is more suitable. 7 and 8 schematically show an embodiment of such a thermoelectric power generation apparatus. FIG. 7 shows a heat receiving member 1 as shown in FIG. 1 based on a flat plate type. FIG. 7A is a plan view and FIG. 7A is a rear view. 8 is based on a type in which the heat receiving member 1 has fins 5 as shown in FIG. 4, FIG. 8A is a plan view, and FIG. 8A is a rear view. In any case, a plurality of thermoelectric element modules 2 are attached to a single heat receiving member 1 at equal intervals in the vertical and horizontal directions.

  Accordingly, in such an embodiment, the heat receiving member 1 has an effective projected area satisfying [A1]> [A2] with respect to the total heat receiving area [A2] of the heat receiving surfaces 20 of the plurality of thermoelectric element modules 2 [ A1]. Moreover, it is preferable that the total heat receiving area [A2] of the effective projected area [A1] of the heat receiving member 1 and the heat receiving surfaces 20 of the plurality of thermoelectric element modules 2 satisfy [A1] ≧ [A2] × 2.3. . Further, the length [X1] of one side of the heat receiving member 1 section (square section section) partitioned by imaginary lines in FIGS. 7A and 8B is the heat receiving surface of each thermoelectric element module 2. The length of one side of 20 is preferably 1.5 times or more of the length [X2].

In the thermoelectric generator of the present invention, the heat receiving member 1 does not have to be flat, and can take various forms (shapes / structures). One of them is a form in which the heat source is provided so as to at least partially surround it, for example, a tunnel-shaped or dome-shaped heat receiving member 1 covering the heat source. Usually, a plurality of thermoelectric element modules 2 are attached to such a heat receiving member 1.
FIG. 9 is a front view schematically showing an embodiment of such a thermoelectric generator. In this embodiment, the heat source is a high-temperature pipe body 6a, which covers the pipe body 6a placed horizontally or transported in the horizontal direction (enclosed except for the lower surface side in the circumferential direction of the pipe body) or A dome-shaped heat receiving member 1 is provided, and a plurality of thermoelectric element modules 2 are attached to the heat receiving member 1. Although the heat receiving member 1 may have an arc shape in cross section, the heat receiving member 1 is configured in a cross sectional shape in which a plurality of planes are combined into a polygonal shape in consideration of the attachment of the heat receiving surface 20 of the thermoelectric element module 2.

In the thermoelectric generator of the present invention, the front surface of the heat receiving member 1 can be subjected to a black body treatment in order to enhance the heat collecting effect of the heat receiving member 1. When the fins 5 are provided on the front surface of the heat receiving member 1, the fins 5 are also included in the target for black body processing. This black body treatment increases the amount of heat absorbed by radiant heat transfer. The black body treatment is usually performed by applying a black body paint.
In general, there is no perfect black body paint having an emissivity ε = 1. However, when the heat receiving member 1 has the fins 5 in particular, the apparent emissivity improving effect described above can be obtained, so that it can be regarded as a complete black body. The amount of heat received is improved to a certain extent.

Among the heat sources to which the thermoelectric power generation device of the present invention is applied, as a typical heat source in the steel manufacturing process, there is a high-temperature steel material, for example, a slab (slab) carried into the slab yard or in the middle of carrying in, A product (for example, a hot rolled coil, a tubular body, a thick plate, etc.) which is carried into the product yard after hot working or is being carried in can be used. The thermoelectric generator of the present invention can also be applied to a heat source (waste heat source) other than the steel manufacturing process.
Therefore, the thermoelectric power generation method of the present invention uses the thermoelectric power generation device of the present invention as described above to generate power using the steel material in the steel manufacturing process as a heat source. As described above, by using the thermoelectric power generation apparatus of the present invention and performing thermoelectric power generation using a steel material at a high temperature (temperature exceeding room temperature) in the steel manufacturing process as described above, sensible heat recovery has hardly been achieved in the past. Efficient power generation can be performed using the waste heat of the high-temperature steel material in the steel manufacturing process, so that energy can be used effectively and energy efficiency in the integrated steelworks can be improved.

In that case, as described above, it is preferable to be able to adjust the distance of the thermoelectric generator to the heat source, and furthermore, the power generation output by the thermoelectric power generator is monitored, and according to the monitored power output, It is preferable to adjust the distance of the thermoelectric generator.
Here, the surface temperature of the steel material serving as a heat source is preferably 300 ° C. or higher. If the surface temperature of the steel material is less than 300 ° C., it is difficult to generate power efficiently, and it is necessary to make the heat receiving member 1 and the fins 5 excessively large.

Assuming a heat source such as a high-temperature steel material, an experiment using an experimental apparatus of the present invention example as shown in FIG. 10 was conducted. FIG. 10A is a plan view of the experimental apparatus, and FIG. 10A is a rear view of the experimental apparatus. What heated the back surface of the steel plate 7 (plate thickness: 5 mm, size: 500 mm x 500 mm) with the ceramic heater 8 was made into the heat source 6, and the steel plate temperature (average temperature) was kept constant at 325 degreeC. The experimental apparatus according to the present invention includes a copper heat receiving member 1 having fins 5 on the front surface 10 and a Bi-Te thermoelectric element module 2 joined to the rear surface 11 via the heat receiving surface 20 side. The heat receiving member 1 has a plate of 100 mm × 100 mm square and an effective projection area [A1] of 100 cm ² , has fins 5 on the front surface, and uniformly applies black body paint to the front surface (heat receiving surface) including the fins 5. It is. The heat receiving surface 20 of the Bi-Te-based thermoelectric element module 2 is a 45 mm × 50 mm square, and the heat receiving area [A2] is 22.5 cm ² . The heat receiving surface 20 was joined to the back surface 11 of the heat receiving member 1 through the high heat conductive sheet 3 having a thickness of 2 mm. In this experiment, the distance (distance) d between the experimental apparatus and the heat source 6 was changed in three stages of 200 mm, 50 mm, and 10 mm, and the generated power was measured by connecting a resistance load to the apparatus.
Further, as a comparative example, an experiment apparatus having the same configuration as described above except that the heat receiving member 1 was not used was used, and an experiment similar to the experiment apparatus of the present invention example was performed to measure the generated power.

  FIG. 11 shows the measurement result of the generated power P by the experimental apparatus of the present invention, and FIG. 12 shows the measurement result of the generated power P by the experimental apparatus of the comparative example. In each graph, the electric power P generated at each interval (distance) d from the heat source 6 is shown with the horizontal axis being the current I. According to this, the generated power of the device of the present invention shown in FIG. 11 is about 10 times the generated power of the device of the comparative example shown in FIG. 12, and an extremely large heat collecting effect is obtained. It can be seen that In particular, it is considered that the increase in the generated power P at intervals shorter than d = 50 mm is greatly influenced by convective heat transfer through the fins 5 of the heat receiving member 1.

DESCRIPTION OF SYMBOLS 1 Heat receiving member 2 Thermoelectric element module 3 Sheet | seat 4 Plate-shaped main body 5 Fin 6 Heat source 6a Tubing body 10 Front surface 11 Back surface 20 Heat receiving surface 50 Plate

Claims (18)

A heat receiving member (1) having a front surface facing the heat source, and one or more thermoelectric element modules (2) joined to the back surface of the heat receiving member (1) via the heat receiving surface (20) side; Effective projected area [A1] in which member (1) satisfies [A1]> [A2] with respect to the total heat receiving area [A2] of the heat receiving surface (20) of one or more thermoelectric element modules (2) A thermoelectric generator having
A thermoelectric power generation method, wherein power generation is performed using a steel material in a steel manufacturing process as a heat source.   The thermoelectric power generation method according to claim 1, wherein power generation is performed using a steel material having a surface temperature of 300 ° C. or more as a heat source.   The thermoelectric power generation method according to claim 1, wherein the thermoelectric power generation device is capable of adjusting a distance to the heat source.   The thermoelectric power generation method according to claim 3, wherein the power generation output by the thermoelectric power generation device is monitored, and the distance of the thermoelectric power generation device to the heat source is adjusted according to the monitored power generation output.   In the thermoelectric generator, the total heat receiving area [A2] of the effective projected area [A1] of the heat receiving member (1) and the heat receiving surface (20) of the thermoelectric element module (2) is [A1] ≧ [A2] × 2. The thermoelectric power generation method according to claim 1, wherein the thermoelectric power generation method according to claim 1 is satisfied.   The thermoelectric power generation method according to any one of claims 1 to 5, wherein the heat receiving member (1) of the thermoelectric power generator has a fin (5) on the front surface side thereof.   The thermoelectric power generation method according to claim 1, wherein the thermoelectric power generation device includes a heat receiving member (1) that at least partially surrounds the heat source.   The thermoelectric power generation method according to claim 7, wherein the thermoelectric power generation device includes a tunnel-shaped or dome-shaped heat receiving member (1) covering the heat source.   The thermoelectric power generation method according to claim 1, wherein the front surface of the heat receiving member (1) is blackbody-treated. A heat receiving member (1) having a front surface facing the heat source, and one or more thermoelectric element modules (2) joined to the back surface of the heat receiving member (1) via the heat receiving surface (20) side;
The heat receiving member (1) has an effective projected area satisfying [A1]> [A2] with respect to the total heat receiving area [A2] of the heat receiving surface (20) of one or more thermoelectric element modules (2) [ A1]. A thermoelectric power generator characterized by having A1].   The thermoelectric generator according to claim 10, wherein the distance to the heat source is adjustable.   The thermoelectric power generation apparatus according to claim 11, further comprising a device for monitoring the power generation output, wherein the distance to the heat source can be adjusted according to the power generation output monitored by the device.   The total heat receiving area [A2] of the effective projected area [A1] of the heat receiving member (1) and the heat receiving surface (20) of the thermoelectric element module (2) satisfies [A1] ≧ [A2] × 2.3. The thermoelectric power generator according to any one of claims 10 to 12.   The thermoelectric power generation according to any one of claims 10 to 13, wherein the heat receiving surface (20) of the thermoelectric element module (2) is joined to the back surface of the heat receiving member (1) directly or via a sheet. apparatus.   The thermoelectric generator according to any one of claims 10 to 14, wherein the heat receiving member (1) has fins (5) on the front side thereof.   The thermoelectric generator according to any one of claims 10 to 15, further comprising a heat receiving member (1) that at least partially surrounds the heat source.   17. The thermoelectric generator according to claim 16, further comprising a tunnel-shaped or dome-shaped heat receiving member (1) covering the heat source.   The thermoelectric generator according to any one of claims 10 to 17, wherein the front surface of the heat receiving member (1) is black-body treated.

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