Heat recovery system

Abstract

The invention relates to a heat recovery system comprising: a main pipe (1) designed such that a flow of hot fluid from an industrial installation circulates inside same, wherein the main pipe (1) comprises a plurality of holes (2); a plurality of light tubes (3) that pass through the corresponding holes (2), such that a first end (4) and a second end (5) of each light tube (3) are located in line with, respectively, the inside and the outside of the main pipe (1), wherein the light tubes (3) are designed to transport photons from the inside of the main pipe (1) to the outside of the main pipe (1); and a plurality of photovoltaic cells (6), wherein each photovoltaic cell (6) is coupled to the second end (5) of at least one light tube (3).

Description

[0001] DESCRIPTION

[0002] Heat recovery system

[0003] Object of the invention

[0004] The present invention relates to a heat recovery system that allows the recovery of thermal energy from a fluid in an industrial process, and transforms said thermal energy into electrical energy from photovoltaic cells.

[0005] Through the heat recovery system, the subject of this invention, heat is captured in industrial environments where there is a circulating gas at high temperature, achieving a highly efficient and robust system that improves the profitability of industrial facilities operating with high-temperature fluids.

[0006] The heat recovery system, the subject of the present invention, is of particular application in any industry that uses or operates with high-temperature fluids.

[0007] Background of the invention and technical problem to be solved

[0008] Heat recovery in industrial processes is a well-established practice for improving energy efficiency and reducing operating costs. Traditionally, conventional heat exchangers—such as shell and tube exchangers or heat pipes—have been used to transfer thermal energy to a working medium (water, air, etc.) for subsequent use in other processes or for power generation.

[0009] In the field of thermophotovoltaic conversion, devices have been developed that harness thermal radiation to generate electricity. WO 2023215182A1 describes a thermophotovoltaic device incorporating a flat (or nearly flat) intermediate layer between a thermal emitter and a photovoltaic cell. This intermediate layer, made of a thermally insulating and transparent material (e.g., glass) with a refractive index greater than 1.4, is designed to maximize photon transmission by minimizing losses due to reflection and heat dissipation.

[0010] However, the device described in the document cited above comprises a design and configuration that are not suitable for integration into an industrial environment operating with pipes that carry a high-temperature gas.

[0011] Description of the invention

[0012] In order to solve the aforementioned problems, the present invention relates to a heat recovery system.

[0013] The heat recovery system, which is the subject of the present invention, comprises:

[0014] - a main pipe configured to connect to at least one pipe of an industrial installation, wherein the main pipe is configured to allow the circulation of a hot fluid flow from the industrial installation through the interior of the main pipe, wherein the main pipe comprises a plurality of holes;

[0015] - a plurality of light tubes (or optical guides), wherein each light tube is arranged passing through a corresponding hole in the main pipe, such that a first end of each light tube is located in correspondence with the inside of the main pipe, and a second end of each light tube is located in correspondence with the outside of the main pipe, wherein the light tubes are configured to transport photons (of infrared radiation) from the inside of the main pipe to the outside of the main pipe; and a plurality of photovoltaic cells, wherein each photovoltaic cell is coupled to the second end of at least one light tube.

[0016] According to a first embodiment of the heat recovery system, the main pipe does not comprise any internal lining.

[0017] According to a second embodiment of the heat recovery system, the main pipe comprises an internal lining composed of a thermal storage material configured to accumulate heat and emit infrared radiation to the light tubes.

[0018] In this second embodiment, the first end of each light tube can be configured to be immersed in the inner lining of the main pipe.

[0019] According to a third embodiment of the heat recovery system, the photovoltaic cells are bifacial, where each light tube has its second end curved, so that each photovoltaic cell is coupled, on each of its two faces, to a corresponding second curved end of a corresponding light tube.

[0020] The coupling between each light tube and the corresponding photovoltaic cell can be done using a transparent adhesive (optical adhesive), preferably with a high refractive index.

[0021] The heat recovery system may include a cooling subsystem, configured to cool the photovoltaic cells.

[0022] The main pipe may be made of and / or may comprise insulation made of a refractory material.

[0023] The invention described overcomes the limitations of existing systems through the synergistic integration of several innovative elements:

[0024] - Use of light tubes (with the possibility of being curved) in an industrial environment: the invention introduces the incorporation of light tubes made of materials with high thermal resistance (such as quartz) that are inserted through holes in the wall or walls of a pipe through which gas circulates at temperatures above 600 °C. The possible curvature of these tubes - designed to approximate 90° (in the shape of a horseshoe or magnet) - allows both inner ends to be located inside the pipe, maximizing heat capture, while their outer ends are strategically positioned for optimal radiation transfer.

[0025] Integration of bifacial photovoltaic cells: In a preferred embodiment, the outer ends of two light tubes are coupled to the two faces of a bifacial photovoltaic cell. This enables the cell to absorb radiation from both sides, significantly increasing the conversion of energy into electricity. This dual-capture strategy contrasts with other possible devices that have a unidirectional interface and, therefore, exhibit lower conversion efficiency. Furthermore, the use of bifacial cells in this case allows for increased efficiency, since the thermal radiation not absorbed by the cell will continue its path through the light tube and be returned to the heat source, thus increasing the system's efficiency.

[0026] - Thermal insulation and advanced heat management: The industrial environment is thermally insulated using materials such as refractory bricks or ceramic wool, and the light tubes are inserted through them, substantially reducing heat loss to the surroundings. This insulation not only optimizes energy transfer to the light tubes but also protects sensitive components, such as photovoltaic cells, from extreme conditions and corrosive environments.

[0027] Incorporation of thermal storage materials: In another embodiment of the invention, the inner wall or walls of the pipe can incorporate thermal storage materials. These materials allow heat to be accumulated and released gradually, so that radiation is emitted even in the absence of a continuous flow of hot gas. This feature extends the period of electricity generation without needing to increase the active area of ​​the photovoltaic cells, thus offering more stable and prolonged energy conversion. - Optimization of optical transmission through specialized interfaces:

[0028] The coupling between the end of the light tube and the photovoltaic cell can be achieved using optical adhesives or nanostructures that ensure a continuous refractive index at the interface, minimizing reflection losses. This optimization maximizes the amount of transmitted radiation and, consequently, the efficiency of converting thermal energy into electrical energy.

[0029] In summary, the present invention offers a unique solution for heat recovery in industrial environments. The combination of light tubes (which can be curved), photovoltaic cells (which can be bifacial), optimized thermal insulation, the incorporation of thermal storage materials, and an improved optical interface overcome the limitations of conventional thermophotovoltaic devices, providing a highly efficient and robust thermal-to-electrical energy conversion system.

[0030] Brief description of the figures

[0031] A series of figures, non-limiting examples, are briefly described here to help to better understand the invention:

[0032] Figure 1 shows a schematic view of a first embodiment of the heat recovery system, the subject of the present invention.

[0033] Figure 2 shows a schematic view of a second embodiment of the heat recovery system, the subject of the present invention.

[0034] Figure 3 shows a schematic view of a possible third embodiment of the heat recovery system, which is the subject of the present invention. Detailed description

[0035] A description of possible ways of implementing the heat recovery system, the subject of the present invention, is then made.

[0036] The heat recovery device or system, the subject of the present invention, comprises a main pipe (1) (or main duct) configured to connect to an industrial installation in which pipes are used through which a high-temperature fluid circulates.

[0037] Thus, the main pipe (1) comprises one or two ends configured to be coupled to said pipes of an industrial installation.

[0038] The main pipe (1) is therefore configured to allow the circulation of a high-temperature fluid through it (typically, a hot gas at a temperature above 600 e C).

[0039] The main pipe may be made of and / or include insulation composed of a refractory material (9) such as refractory bricks or ceramic wool. This improves the thermal efficiency of the system by minimizing heat loss.

[0040] The main pipe (1) comprises a plurality of holes (2) through which corresponding light tubes (3) (or optical guides) run, configured to carry photons from inside the main pipe (1) to the outside of the main pipe (1).

[0041] These light tubes (3) are made of transparent material that is resistant to high temperatures.

[0042] A first end (4) (or inner end) of each light tube (3) is located in correspondence with the inside of the main pipe (1), while a second end (5) (or outer end) of each light tube (3) is located in correspondence with the outside of the main pipe (1).

[0043] The second end (5) of each light tube (3) is coupled to a photovoltaic cell (6).

[0044] Figure 1 shows a first embodiment of the heat recovery system, the subject of the present invention, according to which the first end (4) of each light tube (3) is configured to be in direct contact with the fluid that is to circulate through the main pipe (1).

[0045] Figure 2 shows a second embodiment of the heat recovery system, the subject of the present invention, wherein the main pipe (1) comprises an internal lining (10) composed of a thermal storage material, capable of accumulating heat and emitting infrared radiation to the light tubes (3) even when there is no flow of hot fluid circulating through the main pipe (1), allowing for prolonged electricity generation.

[0046] In this second embodiment of the heat recovery system, the first end (4) of each light tube (3) is preferably configured to be immersed in the inner lining (10) of the main pipe (1).

[0047] According to a third embodiment of the heat recovery system, the subject of the present invention, each light tube (3) has its second end (5) curved (preferably with a curvature of approximately 90°). e ), so that the second ends (5) of two light tubes (3) can be arranged (in a horseshoe or magnet shape), respectively, in correspondence with each of the two faces of a bifacial photovoltaic cell (6). This configuration maximizes radiation capture and doubles the electrical power density generated by the photovoltaic cell (6). Figure 3 shows the feature mentioned in the previous paragraph (intrinsic to the third embodiment of the invention) combined with the feature of the internal lining (10) of the main pipe (1) (intrinsic to the second embodiment).

[0048] However, these intrinsic characteristics of the second and third embodiments can occur independently in the heat recovery system.

[0049] The coupling between each light tube (3) and the corresponding photovoltaic cell (6) can be achieved using an optical adhesive (a transparent adhesive (7), preferably with a high refractive index) or a nanostructure that ensures a continuous refractive index at the interface, minimizing reflection losses. This feature maximizes the amount of transmitted radiation and, consequently, the efficiency of converting thermal energy into electrical energy.

[0050] The heat recovery system may also comprise a cooling subsystem (8), configured to cool the photovoltaic cells (6).

Claims

CLAIMS 1. Heat recovery system characterized in that it comprises: - a main pipe (1) configured to connect to at least one pipe of an industrial installation, wherein the main pipe (1) is configured to allow the circulation of a hot fluid flow from the industrial installation through the interior of the main pipe (1), wherein the main pipe (1) comprises a plurality of holes (2); - a plurality of light tubes (3), wherein each light tube (3) is arranged passing through a corresponding hole (2) of the main pipe (1), such that a first end (4) of each light tube (3) is located in correspondence with the inside of the main pipe (1), and a second end (5) of each light tube (3) is located in correspondence with the outside of the main pipe (1), wherein the light tubes (3) are configured to transport photons from the inside of the main pipe (1) to the outside of the main pipe (1); and - a plurality of photovoltaic cells (6), wherein each photovoltaic cell (6) is coupled to the second end (5) of at least one light tube (3).

2. Heat recovery system according to claim 1, characterized in that the main pipe (1) comprises an internal lining (10) composed of a thermal storage material configured to accumulate heat and emit infrared radiation to the light tubes (3).

3. Heat recovery system according to claim 2, characterized in that the first end (4) of each light tube (3) is configured to be immersed in the inner lining (10) of the main pipe (1).

4. Heat recovery system according to any of the preceding claims, characterized in that the photovoltaic cells (6) are bifacial, wherein each light tube (3) has its second end (5) curved, so that each photovoltaic cell (6) is coupled, on each of its two faces, to a corresponding second curved end (5) of a corresponding light tube (3).

5. Heat recovery system according to any of the preceding claims, characterized in that the coupling between each light tube (3) and the corresponding photovoltaic cell (6) is made by means of a transparent adhesive (7).

6. Heat recovery system according to any of the preceding claims, characterized in that it comprises a cooling subsystem (8), configured to cool the photovoltaic cells (6).

7. Heat recovery system according to any of the preceding claims, characterized in that the main pipe is made of and / or comprises insulation composed of a refractory material (9).

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