Concentrator of solar radiation, and corresponding solar power plant

Abstract

A concentrator (C) of incident solar radiation exhibiting a solar spectrum, the concentrator (C) comprising: - a parabolic trough mirror (1), arranged to receive the incident solar radiation, designed to reflect a first spectral region of the solar spectrum; - an array of reflectors (2), arranged above the parabolic trough mirror (1) to receive the incident solar radiation, designed to transmit the first spectral region to the parabolic trough mirror (1) and reflect a second spectral region, different from the first spectral region. Figure 1

Description

Title of the invention: Solar radiation concentrator, and corresponding solar power plant technical field

[0001] The invention relates to the technical field of solar concentrators.

[0002] The invention finds its application in particular in parabolic trough concentrating solar power plants. State of the art

[0003] A solar power plant known from the prior art comprises: - at least one parabolic cylindrical mirror, arranged to receive incident solar radiation, and designed to reflect a spectral range of the solar spectrum; - a receiver, arranged to receive the spectral domain reflected by the parabolic cylindro-mirror.

[0004] The receiver may be a photovoltaic cell or a photoelectrochemical cell. A photoelectrochemical cell comprises a photoanode and a photocathode sensitive to solar radiation. By way of non-limiting example, the photoanode may comprise a photocatalytic layer made of titanium dioxide (TiO2), while the photocathode may comprise a photocatalytic layer made of copper oxide (Cu2O). Such a photoelectrochemical cell-type receiver is not entirely satisfactory in terms of efficiency (or performance) since titanium dioxide (TiO2) absorbs in the ultraviolet range (wavelength less than 400 nm) and ultraviolet radiation represents only about 3% of the sun's electromagnetic energy.Infrared radiation represents the majority (approximately 45%) of the sun's electromagnetic energy, and leads to a massive transfer of heat to the photoelectrochemical cell, which is likely to degrade over time.

[0005] A person skilled in the art seeks a concentrator that allows efficient use of different types of receivers in the solar power plant, for example thermal receivers, photovoltaic cell type receivers, photoelectrochemical cell type receivers, etc. Description of the invention

[0006] The invention aims to remedy, in whole or in part, the aforementioned drawbacks. To this end, the invention relates to a concentrator of incident solar radiation exhibiting a solar spectrum, the concentrator comprising: - a parabolic cylindrical mirror, arranged to receive incident solar radiation, designed to reflect a first spectral region of the solar spectrum; - a set of reflectors, arranged above the parabolic-cylindrical mirror to receive the incident solar radiation, designed to transmit the first spectral domain to the parabolic-cylindrical mirror and reflect a second spectral domain, different from the first spectral domain.

[0007] Thus, such a concentrator according to the invention allows the efficient use of different types of receivers. A first type of receiver, adapted to operate efficiently in the first spectral range, can receive the solar radiation reflected by the parabolic trough mirror. A second type of receiver, adapted to operate efficiently in the second spectral range, can receive the solar radiation reflected by the array of reflectors.

[0008] The concentrator according to the invention may include one or more of the following characteristics.

[0009] According to one feature of the invention, the reflectors of the assembly are chosen from dichroic mirrors and Bragg mirrors.

[0010] Thus, an advantage provided by such reflectors is the possibility of easily designing them to transmit a first spectral domain and to reflect a second spectral domain, different from the first spectral domain.

[0011] According to a feature of the invention, the parabolic cylindrical mirror is made of a material chosen from silver and aluminum.

[0012] Thus, an advantage provided by such materials is to obtain a high intensity reflection coefficient over a large spectral range of the solar spectrum.

[0013] According to a feature of the invention: - the first spectral domain includes at least one spectral range in the infrared; - the second spectral domain includes at least one spectral range in the ultraviolet.

[0014] Thus, one advantage provided is the ability to efficiently use different types of receivers. A thermal receiver, adapted to operate efficiently in the first spectral range, can receive the solar radiation reflected by the parabolic trough mirror. A second type of receiver (e.g., a photovoltaic cell, a photoelectrochemical cell), adapted to operate efficiently in the second spectral range, can receive the solar radiation reflected by the array of reflectors.

[0015] According to one feature of the invention, the concentrator comprises a structure having first and second opposing support surfaces, transparent in the solar spectrum; the parabolic-cylindrical mirror extending over the first support surface, the assembly of reflectors extending over the second support surface.

[0016] Thus, one advantage provided is to facilitate the mounting of the parabolic cylindro-mirror and the set of reflectors.

[0017] According to one feature of the invention, the structure comprises an air gap, transparent in the solar spectrum, arranged between the first and second opposing support surfaces.

[0018] Thus, one advantage provided is to obtain a high intensity transmission coefficient over a large spectral range of the solar spectrum.

[0019] According to one feature of the invention, the structure comprises a plate transparent in the solar spectrum, including the first and second opposing support surfaces.

[0020] Thus, one advantage provided is to obtain good mechanical strength of the parabolic cylindrical mirror and the assembly of reflectors.

[0021] According to one feature of the invention, the plate is made of a material chosen from extra-clear glass, polycarbonate, polymethyl methacrylate, polyvinyl chloride.

[0022] Thus, one advantage provided is to obtain a high intensity transmission coefficient over a large spectral range of the solar spectrum.

[0023] According to one feature of the invention, the structure includes means of displacement, configured to move the first and second support surfaces according to a direction of the incident solar radiation, so as to orient the parabolic cylindro-mirror and the assembly of reflectors to receive a maximum intensity of the incident solar radiation.

[0024] Thus, one advantage provided is to optimize the intensity of the radiation reflected by the parabolic cylindrical mirror and by the set of reflectors.

[0025] The invention also relates to a solar power plant, comprising: - at least one concentrator conforming to the invention; - at least one first receiver, arranged to receive the first spectral domain reflected by the parabolic cylindro mirror of at least one concentrator; - at least one second receiver, arranged to receive the second spectral domain reflected by the set of reflectors of at least one concentrator.

[0026] Thus, such a solar power plant according to the invention allows for the efficient use of different types of receivers. The first receiver(s), adapted to operate efficiently in the first spectral range, are arranged to receive the solar radiation reflected by the parabolic trough mirror. The second receiver(s), adapted to operate efficiently in the second spectral range, are arranged to receive the solar radiation reflected by the reflector assembly.

[0027] Definitions

[0028] - The term "concentrator" refers to a solar concentrator.

[0029] - By "reflecting", it is meant that the parabolic cylindro-mirror has a co The reflectance efficiency must be greater than 80%, preferably greater than 85%, and more preferably greater than 90%, averaged over the first spectral range. Similarly, the reflector array must have a reflectance coefficient greater than 80%, preferably greater than 85%, and more preferably greater than 90%, averaged over the second spectral range.

[0030] - By "transmit", it is meant that the set of reflectors has a coefficient transmission intensity greater than 80%, preferably greater than 85%, more preferably greater than 90% averaged over the first spectral domain.

[0031] - By "first (respectively second) spectral domain", we mean a res reduction of the solar spectrum in terms of lengths reflected respectively by the parabolic cylindrical mirror and by the set of reflectors.

[0032] - By "transparent", it is meant that the elements (first and second surfaces of support, air gap, plate) have an intensity transmission coefficient greater than 80%, preferably greater than 85%, more preferably greater than 90% averaged over the solar spectrum.

[0033] - The term "receptor" can refer to a thermal receptor, that is to say a An adsorber through which a heat transfer fluid circulates, or a receiver of a different nature, for example a photovoltaic cell or a photoelectrochemical cell. Brief description of the drawings

[0034] Other features and advantages will become apparent in the detailed description of different embodiments of the invention, the description being accompanied by examples and references to the accompanying drawings.

[0035] [Fig-1] is a schematic perspective view of a solar power plant according to the invention.

[0036] [Fig.2] is a partial schematic front perspective view of a concentrator according to the invention.

[0037] [Fig.3] is a partial schematic rear perspective view of a concentrator according to the invention.

[0038] [Fig.4] is a partial schematic side view of a solar power plant according to the invention.

[0039] [Fig.5] is a partial schematic side view of a concentrator according to the invention, illustrating the path of incident solar radiation towards the first and second receivers.

[0040] [Fig.6] is a schematic view analogous to [Fig.5], illustrating the path of solar radiation with normal incidence towards the first and second receivers.

[0041] [Fig.7] is a schematic side view at enlarged scale of a part of a concentrator according to the invention, illustrating an angle of inclination between the parabolic cylindro-mirror and a reflector.

[0042] [Fig.8] is a partial schematic view of a solar power plant according to the invention, illustrating the presence of two concentrators.

[0043] [Fig.9] is a partial schematic side view of a concentrator according to the invention, illustrating reflectors having a triangular crenellated shape.

[0044] It should be noted that the drawings described above are schematic and are not necessarily to scale for the sake of legibility and to simplify their understanding. Detailed description of embodiments

[0045] Identical elements or elements performing the same function shall bear the same references for the different embodiments, for the sake of simplification.

[0046] An object of the invention is a concentrator C of incident solar radiation Rs exhibiting a solar spectrum, the concentrator C comprising: - a parabolic cylindrical mirror 1, arranged to receive the incident solar radiation Rs, designed to reflect a first spectral domain Rsl of the solar spectrum; - a set of reflectors 2, arranged above the parabolic-cylindrical mirror 1 to receive the incident solar radiation Rs, designed to transmit the first spectral domain Rsl to the parabolic-cylindrical mirror 1 and reflect a second spectral domain Rs2, different from the first spectral domain Rsl.

[0047] Parabolic cylindro-mirror

[0048] The parabolic-cylindrical mirror 1 is arranged to receive the incident solar radiation Rs. The parabolic-cylindrical mirror 1 is designed to reflect a first spectral region Rsl of the solar spectrum.

[0049] The parabolic cylindrical mirror 1 is advantageously made of a material chosen from silver and aluminium.

[0050] The first spectral domain Rsl advantageously comprises at least one spectral range in the infrared. The first spectral domain Rsl may comprise a spectral range in the infrared, and a spectral range in the visible (wavelengths between 400 nm and 780 nm).

[0051] The parabolic-cylindrical mirror 1 may have a radius of curvature of between 0.5 m and 20 m, preferably between 0.5 m and 15 m. The parabolic-cylindrical mirror 1 may have a focal length of between 0.5 m and 20 m.

[0052] Assembly of reflectors

[0053] The reflector assembly 2 is arranged above the parabolic trough mirror 1. The reflector assembly 2 is arranged to receive the incident solar radiation Rs. The reflector assembly 2 is designed to transmit the first spectral region Rsl to the parabolic trough mirror 1. The reflector assembly 2 is designed to reflect a second spectral range Rs2, different from the first spectral range Rsl. The number and size of the reflectors 2 are chosen according to the desired concentration level.

[0054] The reflectors 2 of the assembly are advantageously chosen from dichroic mirrors and Bragg mirrors. Dichroic mirrors are preferred because of the greater dispersion of the radiation transmitted by Bragg mirrors.

[0055] The second spectral domain Rs2 advantageously comprises at least one spectral range in the ultraviolet. The second spectral domain Rs2 may comprise a spectral range in the ultraviolet and a spectral range in the visible (wavelengths between 400 nm and 780 nm).

[0056] By way of non-limiting example, each reflector 2 of the assembly may be a DMLP425 dichroic mirror, marketed by THORLABS. The intensity reflection coefficient averaged over the spectral range [380 nm; 410 nm] is greater than 95%. The intensity transmission coefficient averaged over the spectral range [440 nm; 800 nm] is greater than 90%.

[0057] Structure

[0058] The concentrator C may comprise a structure 3 having first and second opposing support surfaces 30, 31. The first and second support surfaces 30, 31 are transparent in the solar spectrum. The parabolic-cylindrical mirror 1 extends over the first support surface 30. The reflector assembly 2 extends over the second support surface 31. The reflectors 2 may be formed on the second support surface 31 by a vacuum deposition technique known to those skilled in the art.

[0059] The structure 3 has a first curved support surface 30, having a radius of curvature adapted to the radius of curvature of the parabolic mirror 1 so that the parabolic mirror 1 can extend over the first support surface 30. The structure 3 may have a second crenellated or serrated support surface 31. By way of non-limiting example, the second crenellated support surface 31 may have triangular cross-section patterns. The first and second support surfaces 30, 31 are advantageously arranged so that each reflector 2 extends in an oblique direction (at an angle of inclination α) with respect to the underlying arched portion of the parabolic mirror 1 (more precisely, with respect to the chord of the underlying arched portion). By way of non-limiting example, the angle of inclination α may be between 0.1° and 10°.

[0060] According to a first embodiment, the structure 3 comprises an air blade, transparent in the solar spectrum, arranged between the first and second opposing support surfaces 30, 31.

[0061] According to a second embodiment, the structure 3 comprises a plate Transparent across the solar spectrum, comprising the first and second opposing support surfaces 30, 31. The plate is advantageously made of a material selected from extra-clear glass, polycarbonate, polymethyl methacrylate, or polyvinyl chloride. By way of non-limiting example, the plate may be produced by an extrusion process. The plate may be made by assembling several sub-plates to achieve a lateral dimension on the order of 10 m.

[0062] The structure 3 advantageously comprises movement means 32, configured to move the first and second support surfaces 30, 31 according to a direction of the incident solar radiation Rs, so as to orient the parabolic mirror 1 and the reflector assembly 2 to receive maximum intensity of the incident solar radiation Rs. The movement means 32 may comprise an electric motor and a set of toothed gears. Alternatively, the movement means may comprise a connecting rod (crank) and a hydraulic or electric actuator.

[0063] The structure 3 advantageously comprises uprights 33, on which the movement means 32 are mounted. The structure 3 advantageously comprises offset arms 34, designed to provide an offset (distance) function between the concentrator C and receivers RI, R2. The offset arms 34 are arranged so that the receivers RI, R2 are located in the vicinity of the focus of the parabolic cylindro-mirror 1.

[0064] Solar power plant

[0065] The invention also relates to a solar power plant, comprising: - at least one concentrator C conforming to the invention; - at least one first receiver RI, arranged to receive the first spectral domain Rsl reflected by the parabolic cylindro-mirror 1 of at least one concentrator C; - at least one second receiver R2, arranged to receive the second spectral domain Rs2 reflected by the set of reflectors 2 of at least one concentrator C.

[0066] The first receiver(s) RI and the second receiver(s) R2 are arranged near the focus of the parabolic mirror 1. The first receiver(s) RI can be made in the form of a circular tube with a diameter between 10 mm and 100 mm. The second receiver(s) R2 can be made in the form of a rectangular tube with a width between 10 mm and 2 m.

[0067] The first receiver(s) RI can be a thermal receiver, i.e., an adsorber through which a heat transfer fluid circulates. The second receiver(s) R2 can be a receiver of a different nature, for example, a photovoltaic cell or a photoelectrochemical cell.

[0068] By way of non-limiting example, the solar power plant may include: - two C concentrators; - a first thermal RI receiver; - a second receiver R2, arranged below the first thermal receiver RI.

[0069] The two concentrators C can be arranged in axial symmetry (vertical axis) with respect to the first and second receivers RI, R2.

[0070] The invention is not limited to the embodiments described. A person skilled in the art is able to consider their technically operative combinations, and to substitute equivalents for them.

Claims

Demands

1. Concentrator (C) of incident solar radiation (Rs) exhibiting a solar spectrum, the concentrator (C) comprising: - a parabolic-cylindrical mirror (1), arranged to receive the incident solar radiation (Rs), designed to reflect a first spectral domain (Rs1) of the solar spectrum; - an array of reflectors (2), arranged above the parabolic-cylindrical mirror (1) to receive the incident solar radiation (Rs), designed to transmit the first spectral domain (Rs1) to the parabolic-cylindrical mirror (1) and reflect a second spectral domain (Rs2), different from the first spectral domain (Rs1).

2. Concentrator (C) according to claim 1, wherein the reflectors (2) of the assembly are selected from dichroic mirrors and Bragg mirrors.

3. Concentrator (C) according to claim 1 or 2, wherein the parabolic cylindrical mirror (1) is made of a material selected from silver and aluminum.

4. Concentrator (C) according to any one of claims 1 to 3, wherein: - the first spectral domain (Rs1) comprises at least one spectral range in the infrared; - the second spectral domain (Rs2) comprises at least one spectral range in the ultraviolet.

5. Concentrator (C) according to any one of claims 1 to 4, comprising a structure (3) having first and second opposing support surfaces (30, 31) transparent in the solar spectrum; the parabolic cylindro mirror (1) extending over the first support surface (30), the reflector assembly (2) extending over the second support surface (31).

6. Concentrator (C) according to claim 5, wherein the structure (3) comprises an air blade, transparent in the solar spectrum, arranged between the first and second opposing support surfaces (30, 31).

7. Concentrator (C) according to claim 5, wherein the structure (3) comprises a plate transparent in the solar spectrum, comprising the first and second opposing support surfaces (30, 31).

8. Concentrator (C) according to claim 7, wherein the plate is made of a material selected from extra-clear glass, polycarbonate, polymethyl methacrylate, polyvinyl chloride.

9. Concentrator (C) according to any one of claims 5 to 8, wherein the structure (3) comprises displacement means (32), configured to move the first and second support surfaces (30, 31) according to a direction of the incident solar radiation (Rs), so as to orient the parabolic cylindro-mirror (1) and the reflector assembly (2) to receive a maximum intensity of the incident solar radiation (Rs).

10. Solar power plant, comprising: - at least one concentrator (C) according to any one of claims 1 to 9; - at least one first receiver (RI), arranged to receive the first spectral domain (Rs1) reflected by the parabolic trough mirror (1) of at least one concentrator (C); - at least one second receiver (R2), arranged to receive the second spectral domain (Rs2) reflected by the set of reflectors (2) of at least one concentrator (C).

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