Power generation system using solar heat

Abstract

To construct a solar thermal power generation system by using a thermoelectric conversion element requiring no temperature difference.SOLUTION: There is provided a power generation system including a thermal collector tube, in which the thermal collector tube includes a thermoelectric conversion element, the thermoelectric conversion element has a flat plate shape, and the thermoelectric conversion element is housed inside the thermal collector tube.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power generation system using solar heat. [Background technology]

[0002] Solar energy has been used to generate electricity by using hot water obtained by heating water with solar heat, or by using steam generated by heating water with solar heat to turn a turbine (see, for example, Patent Document 1).

[0003] Furthermore, solar panel power generation is the mainstream of power generation using sunlight. When generating power using solar heat, the most common methods are a boiler system that uses solar heat to boil water and turn a turbine, and a thermoelectric conversion element (Peltier element) that directly converts the water into electricity. For example, see Patent Document 3.

[0004] On the other hand, thermoelectric conversion elements that do not require a temperature difference have been invented, as shown in Patent Documents 2 and 4, and they may be applicable to a variety of power generation applications. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2012 / 042639 [Patent Document 2] Patent No. 7011361 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-166721 [Patent Document 4] International Publication No. 2023 / 038103 Summary of the Invention [Problem to be solved by the invention]

[0006] According to one aspect of the present invention, an object is to construct a solar thermal power generation system using a thermoelectric conversion element that utilizes heat from the sun or the like and does not require a temperature difference. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a power generation system equipped with a heat collection tube, wherein the heat collection tube includes a thermoelectric conversion element that does not require a temperature difference, the thermoelectric conversion element has a bendable flat plate shape, and the thermoelectric conversion element is stored inside the heat collection tube by being rolled or folded. [Effects of the Invention]

[0008] According to one aspect of the present invention, even on cloudy days when solar heat is difficult to reach or at night when solar heat does not reach, power generation can be continued by using the heat preheat stored in the heat collection tube during the day.

[0009] Other objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 shows an example of a thermoelectric power generation system according to an embodiment of the present invention. [Figure 2] FIG. 2 shows an example of a heat collection tube used in a thermoelectric power generation system according to an embodiment of the present invention, where (a) is a cross-sectional view of the heat collection tube, and (b) shows a thermoelectric conversion element connected to a lead wire. [Figure 3] FIG. 3 shows another example of a heat collection tube used in a thermoelectric power generation system according to an embodiment of the present invention, where (a) is a cross-sectional view of the heat collection tube, and (b) shows a thermoelectric conversion element connected to a lead wire. [Figure 4] FIG. 4 shows an example of a configuration in which multiple thermoelectric power generation systems are arranged and connected in series (a) or in parallel (b). [Figure 5] FIG. 5 shows an example of a thermoelectric conversion element used in an embodiment of the present invention. [Figure 6] FIG. 6 shows an example of an auxiliary sheet for a thermoelectric conversion element used in an embodiment of the present invention, where (a) shows an example of an unfolded auxiliary sheet, and (b) shows an example of an auxiliary sheet in use.

[0011] 1 shows an example of a thermoelectric power generation system according to an embodiment of the present invention. In this embodiment, a system that generates power based on solar heat will be described.

[0012] The thermoelectric power generation system 1000 of this embodiment includes a heat collection tube 100. The thermoelectric power generation system 1000 of this embodiment may additionally include a heat collector 200.

[0013] The heat collection tube 100 has a function of collecting and storing solar heat inside the heat collection tube 100 .

[0014] The solar collector 200 is, for example, a reflector plate, and is composed of an upper plate 210, a lower plate 220, and a side plate 230. At least the side plate 230 is configured in a shape that allows it to collect solar heat to the heat collection tube 100 installed in the thermal power generation system 1000. Specifically, the side plate 230 is made of a material that reflects solar heat, such as a mirror or a metal plate, and is arranged in a direction that reflects the solar heat and makes it incident on the heat collection tube 100. Note that although the side plate 230 in this embodiment is composed of multiple flat plates, it may also be composed of a single curved plate.

[0015] The thermoelectric power generation system 1000 of this embodiment may further include a lid 310, an upper fixture 330, and a lower fixture 320 for positioning the heat collection tube 100 in a position where it can efficiently receive solar heat. The lid 310 functions as a plug for the upper opening of the heat collection tube 100. The upper fixture 330 is attached to a portion of the upper plate 210, and the lower fixture 320 is attached to a portion of the lower plate 220, and they fix the heat collection tube 100. In addition, a through-hole may be provided in the lid 310 of the heat collection tube 100, or the lid 310 may simply be removed, allowing the solution 140 inside the thermoelectric power generation system 1000 to evaporate and escape to the outside.

[0016] The thermoelectric power generation system 1000 of this embodiment may be configured to obtain a desired high voltage by arranging multiple thermoelectric power generation systems 1000 and connecting them in series, as shown in Fig. 4(a).Also, as shown in Fig. 4(b), multiple thermoelectric power generation systems 1000 may be connected in parallel, as shown in Fig. 4(b).

[0017] FIG. 2 shows an example of a heat collection tube used in a thermoelectric power generation system according to an embodiment of the present invention.

[0018] As shown in FIG. 2( a ), the heat collection tube 100 of this embodiment includes an outer tube 111 , an inner tube 112 , a thermoelectric conversion element 120 , and a solution 140 .

[0019] The outer tube 111 is made of glass or the like, and has a structure that transmits solar heat to the inner tube 112 . The inner tube 112 is made of glass or the like, and is silver-plated, and has a structure that reflects heat radiation from inside the inner tube 112 and keeps the heat inside. Combining the outer tube 111 and the inner tube 112 creates a structure that can store solar heat inside the heat collection tube 100. Specifically, it has a double-tube structure with cylindrical outer tube 111 and inner tube 112, and a vacuum is created between the outer tube 111 and the inner tube 112. The vacuum insulation effect makes it difficult for solar heat taken into the heat collection tube 100 to escape to the outside.

[0020] The thermoelectric conversion element 120 is, for example, a thermoelectric conversion element that does not require a temperature difference. By using a thermoelectric conversion element that does not require a temperature difference, electricity can be collected directly from solar heat. The thermoelectric conversion element 120 has a bendable flat plate shape, and can be stored inside the heat collection tube 100 by rolling or folding it.

[0021] The solution 140 is an optional component that is filled into the inner tube 112 of the heat collection tube 100. Filling the inner tube 112 with the solution 140 further enhances the heat storage effect compared to a state in which a gas such as air is filled, and the boiling point of the solution suppresses unintended temperature increases inside the heat collection tube 100, thereby preventing damage to the thermoelectric conversion element. Furthermore, since the solar heat obtained during the day can be stored inside the heat collection tube 100, the temperature inside the inner tube 112 can be maintained at a high temperature even if the amount of solar heat received by the heat collection tube 100 decreases. For example, even if the amount of solar heat decreases from evening to night, filling the inner tube 112 with the solution 140 gradually reduces the temperature inside the inner tube 112, allowing power generation to continue for a long period of time beyond the hours of sunshine. The solution 140 is one that is not easily volatilized, has a large heat storage effect, and is low in reactivity and biological and environmental hazards, and examples of such solutions include water, ethylene glycol, polyethylene glycol, alcohol-based solvents such as ethanol, methanol, propyl alcohol, isopropyl alcohol, butanol, hexanol, octanol, nonanol, decanol, tridecanol, and isopropyl alcohol, aliphatic hydrocarbons such as paraffin, olefin, naphthene, lubricating oil, edible oil, glycerin, and silicone oil. Fluorine-based solutions may also be used as long as their biological and environmental safety can be guaranteed.

[0022] In this embodiment, a flat thermoelectric conversion element 120 is housed inside the heat collection tube 100. Unlike systems such as solar panels, where the area that receives light determines the output, the thermoelectric conversion element 120 can be rolled or folded and housed inside the heat collection tube 100, which makes it possible to increase the amount of power generation per unit area and make the power generation system more compact.

[0023] 2(b) shows a thermoelectric conversion element 120 to which conductors 121 and 122 are connected. A conductor 122 and a conductor 121 are attached to an arbitrary location on an electrode 11 and an arbitrary location on an electrode 12 of the thermoelectric conversion element 120, respectively. In addition, a through-hole is provided in the lid 310, and the conductors 121 and 122 can be drawn out through the through-hole to extract the generated electricity.

[0024] 3 shows another example of a heat collection tube used in a thermoelectric power generation system according to an embodiment of the present invention. Here, the differences from the heat collection tube in FIG. 2 will be explained. In the cross-sectional view of the heat collection tube in Fig. 3(a), the conductors 121 and 122 are drawn out from the center of the thermoelectric conversion element 120. In this case, Fig. 3(b) shows the shape of the thermoelectric conversion element to which the conductors are connected, and is configured so that the size (area) of electrode 12 is slightly larger than the size of electrode 11. In this way, by configuring the shape of electrode 11 to be different from the shape of electrode 12, it becomes possible to draw out the conductors 121 and 122 from one surface.

[0025] FIG. 5 shows an example of a thermoelectric conversion element 120 that does not require a temperature difference and is used in an embodiment of the present invention.

[0026] The thermoelectric conversion element 120 includes a first electrode 11, a second electrode 12, and an intermediate portion 14. The thermoelectric conversion element 120 may include, for example, a first substrate 15. The first substrate 15 is made of a flexible and insulating material. The first electrode 11 and the second electrode 12 are disposed opposite each other. The first electrode 11 and the second electrode 12 have different work functions. The electrodes 11 and 12 may be made of a material consisting of a single element, such as platinum, gold, palladium, copper, iron, chromium, cobalt, titanium, nickel, aluminum, zirconium, tungsten, or carbon. Alternatively, alloys consisting of two or more elements, and oxides, nitrides, borides, carbides, and the like, may be used. For details of the thermoelectric conversion element 120 used in one embodiment of the present invention, see Patent Document 2 (Japanese Patent Publication No. 7011361).

[0027] Furthermore, the power generation system of this embodiment is applicable not only to the thermoelectric conversion element 120 that does not require a temperature difference as shown in Patent Document 2 (Patent Publication No. 7011361) and Patent Document 4 (International Publication No. 2023 / 038103), but also to other thermoelectric conversion elements that do not require a temperature difference.

[0028] FIG. 6 shows an example of an auxiliary sheet 600 for the thermoelectric conversion element 120 used in one embodiment of the present invention. The auxiliary sheet 600 of this embodiment is composed of a thermoelectric conversion element 610 (see the thermoelectric conversion element 120 in Figure 5. The thermoelectric conversion element 610 has a first substrate with an insulating function corresponding to the thermoelectric conversion element 120 in Figure 5), a spacer 640, a pair of electrodes 650, and a tube 660. The spacers 640 are arranged along the width direction of the thermoelectric conversion element 610 (the horizontal direction in FIG. 6(a)) and on both the upper and lower end sides of the thermoelectric conversion element 610 (in FIG. 6(a)). The distance between the spacers 640 may be any length, and the number and shape of the spacers 640 may also be any, as long as they are configured to maintain the rolled cylindrical shape in FIG. 6(b) described below and to prevent contact between the outside of the inner thermoelectric conversion element 610 and the inside of the outer thermoelectric conversion element 610 when rolled. Furthermore, the spacers 640 may be heat-resistant and waterproof. Although the spacer 640 of this embodiment has a through-hole inside the spacer 640, in another embodiment, the spacer 640 may have no through-hole. The pair of electrodes 650 are connected to the conductors 121 and 122 of the thermoelectric conversion element 610 (see FIGS. 2 and 3. The thermoelectric conversion element 610 corresponds to the thermoelectric conversion element 120 in FIGS. 2 and 3). The tube 660 has a through hole through which the conductive wires 121, 122 and the pair of electrodes 650 pass. The tube 660 may be configured to serve as a core (center) when the auxiliary sheet 600 is rolled up.

[0029] As shown in FIG. 6(b), the auxiliary sheet 600 of this embodiment can be wound around the thermoelectric conversion elements 610 while ensuring water permeability and preventing contact between the thermoelectric conversion elements, and can be housed in the heat collection tube.

[0030] By using the auxiliary sheet 600 of this embodiment, for example, it is possible to prevent contact between the thermoelectric conversion elements 610, and by bringing the solution into contact with both sides of the thermoelectric conversion elements 610, it is possible to suppress unintended temperature increases and avoid damage to the thermoelectric conversion elements 610.

Claims

1. A power generation system including a heat collection tube, A power generation system characterized in that the heat collection tube includes a thermoelectric conversion element, the thermoelectric conversion element is flat, and the thermoelectric conversion element is housed inside the heat collection tube.

2. 2. The power generation system according to claim 1, wherein the thermoelectric conversion element is a thermoelectric conversion element that does not require a temperature difference.

3. The power generation system according to claim 1, characterized in that a material with high heat storage capacity is used inside the heat collection tube, and heat generated by sunlight during the day is stored inside the heat collection tube, thereby enabling power generation at night as well.

4. 2. The power generation system according to claim 1, further comprising a heat collector arranged to reflect sunlight and make it incident on said heat collection tube.

5. 2. The power generation system according to claim 1, wherein the thermoelectric conversion element comprises a first electrode, a second electrode, and an intermediate portion between the first electrode and the second electrode, and is configured so that one conductor is drawn from any point on the first electrode and the other conductor is drawn from any point on the second electrode.

6. 4. The power generation system according to claim 3, wherein the material with high heat storage capacity in the heat collection tube is a solution.

7. The power generation system according to claim 6, characterized in that a plug is provided in a part of the heat collection tube, and by providing a through-hole in the plug or by removing the plug, the solution can be vaporized and evaporated to the outside through the through-hole.

8. 2. The power generation system according to claim 1, wherein an auxiliary sheet in which spacers are arranged on a thermoelectric conversion element having a first substrate with an insulating function is housed inside the heat collection tube.

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