MXPA01004756A - Solar energy concentrator and converter - Google Patents

Abstract

A solar energy concentrator (1) is formed in the shape of a spiral horn, so that solar energy incident over a wide range of incident angles on the mouth (2) of the horn is concentrated by multiple reflections from inner walls (5) of the horn to emerge from an exit aperture (3) at the centre of the horn. Solar energy emerging from the collector may be distributed by light pipes (40) to illuminate a building or may be transmitted to a solar energy conversion chamber (50) having a small entry aperture (51). The entry aperture (51) acts as black body absorbing all solar energy incident upon it and the solar energy may be converted within the chamber (50) either by photovoltaic cells and/or by heat absorbing media.

Description

CONCENTRATOR AND SOLAR ENERGY CONVERTER FIELD OF THE INVENTION This invention relates to a solar energy concentrator, a solar energy concentrator in combination with a solar energy distributor and a solar energy concentrator in combination with a solar energy conversion chamber . BACKGROUND OF THE INVENTION Solar energy concentrators, for use prior to the conversion of solar energy into other useful forms of energy, are well known. Concentrated solar energy can be used in a solar furnace or converted to other forms of energy, for example, by a thermally absorbent medium, which usually contains a fluid, or by a photovoltaic cell. Known solar concentrators include parabolic dish receivers which, to focus direct sunlight, follow the sun's path through the sky. These devices are usually built on towers which must be able to withstand the substantial shear stress of the wind, while a minimum of shade is produced on the surface of the collector. The shape of the collector must remain constant during the time, and REF: 129198 Tracking the trajectory must be exact to maintain an angle of incidence with a degree throughout the day. In addition, when used in conjunction with a Stirling engine there are also potential problems of wind gusts that create fluctuations in the heat exchange and therefore, in the energy output. The use of land (8-17 acres per megawatt, 3.2-6.9 hectares / mega att), site preparation, installation, capital costs and maintenance of heliostats in the towers, are also expensive. Solar concentrators, which use either a lens or a composite reflective surface, are also commercially available but also require tracking mechanisms to track the movement of the sun across the sky. The cost of purchase, installation, maintenance and the associated land requirements are again substantial. Several solar concentrators are also known, which do not require tracking or tracing mechanisms, however, they suffer from several limitations, for example, the acceptance angle of some of the concentrators is limited so that the sun's rays can be received only during a small portion of the day. In others, a concentration factor can be satisfactory only for a limited time of the day. However, known concentrators are designed for operation with direct sunlight, and do not work satisfactorily in diffused or scattered light. For example, the solar collector of US-A-4287880 (Geppert) comprises a reflector formed of three separate curves, which focus solar energy on the collector pipe, so that the rays of sunlight having different angles of incidence are reflected by different parts of the reflector on the manifold pipe to heat a fluid flowing through the pipe. However, the device can not effectively concentrate the diffuse light and is therefore limited in its geographical application. The efficiency of the pipe absorber will also vary as a function of the ambient air temperature, because the absorption of heat, transfer and collection is external to the device. An involute beam concentrator described in US-A-4610518 (Clegg) uses an involute chamber to convert a rectangular rectangular beam of emergent sunlight from a prismatic beam concentrator into a concentrated solar beam parallel to a concentrator axis. This concentrator is designed to accept solar input power from the prismatic beam collector only over a very small range of incident angles. The use of photovoltaic cells in the form of silicon solar cells also suffers from the disadvantage that the spectral distribution of sunlight has a maximum spectral glow at a wavelength of 540 nanometers while the maximum sensitivity of solar cells occurs at 813 nanometers. As a result, much energy that falls in the solar cell is not converted into electricity. On the other hand, these solar cells have to be cooled to maintain operational peak efficiency. US-A-4947292 (Vlah) describes a lighting system designed to produce a diffused light from a concentrated light source, in which a concentrated light source is located at the focus of a spiral-shaped horn and the diffuse light is emitted from the mouth of the horn. A preferred form of the spiral is a 'Gold Section Spiral', also known as a scroll, formed of a series of rectangles of * Golden Section "one inside another, that is, rectangles in which the proportion of the lengths of the largest and smallest sides are (1 +) l, which can be used to locate the centers of the "Golden Section" for the arcs that make a spiral of * Golden Sections. "BRIEF DESCRIPTION OF THE INVENTION It is an object of this invention to provide a solar energy concentrator, a solar energy concentrator in combination with an energy distributor and a solar energy concentrator in combination with a solar energy conversion chamber which at least partially mitigates some of the difficulties of the prior art According to a first aspect of the invention, there is provided a solar energy concentrator comprising a spiral horn having a perpendicular axis to a plane of the spiral, the concentrator includes: an inlet opening forming a horn mouth, an internal light reflecting surface of the horn, and an outlet opening at one end of the horn away from the mouth of the horn, the opening outlet is smaller than the entrance opening and the horn is continuously tapering both in the direction of the axis and in the plane of the spiral, between the inlet and outlet openings, where the horn is adapted to concentrate, by multiple reflections from the internal light reflecting surface of the horn, the incident solar energy within a predetermined range of incident angles at the entrance opening, so that concentrated solar energy is emitted from the exit opening. Preferably at least one guideline is provided at the mouth of the horn to reflect the incidence of light from outside the predetermined range of incidence angles in the predetermined range of incidence angles. Conveniently, at least one guideline is a deflector positioned substantially parallel to the axis of the spiral horn. Advantageously, at least one guideline is a partial spiral horn positioned substantially perpendicular to the axis of the spiral horn in at least a portion of the spiral horn closest to the mouth of the horn. Conveniently, the spiral horn has a substantially quadrilateral cross section, parallel to the axis of the horn. Advantageously, the conical waveguide in the plane of the spiral is a Gold Spiral, Conveniently the horn is made of metal.

Advantageously, the metal is aluminum. Preferably the horn has portions formed of different materials placed along the spiral of the horn, the materials being adapted to withstand the temperatures reached in the respective portions of the collector in use. Advantageously, a portion of the horn near the outlet opening is made of a ceramic material. Conveniently, the light reflecting surface is protected by ultraviolet radiation absorption means. According to a second aspect of the invention there is provided a solar energy concentrator according to the first aspect in combination with the distribution means in communication with the outlet opening and adapted to distribute the concentrated solar energy emitted from the outlet opening. . Preferably the distribution means includes at least one conductor for light. Advantageously, the distribution means include a diffuser for diffusion to at least some of the concentrated solar energy to provide illumination.

Conveniently, the diffuser is in the shape of a spiral horn. According to a third aspect of the invention, a solar energy concentrator is provided according to the first aspect, in combination with a solar energy conversion chamber having an opening in the chamber in communication with the outlet opening of the concentrator , the chamber contains energy conversion means to convert the concentrated solar energy emitted from the outlet opening. Advantageously, the energy conversion means include a photovoltaic cell. Conveniently, the energy conversion means include heat absorbing means. Advantageously, the energy conversion means include means that generate steam. Conveniently, the energy conversion means include a solar oven. Advantageously, at least some of the solar energy is reflected inside the chamber before it affects the energy conversion means.

Advantageously, at least some of the solar energy experiences wavelength changes within the chamber. Conveniently, solar energy suffers wavelength increases by the absorption and / or dissipation of energy. Conveniently, means of distributing solar energy are provided to transmit solar energy from the outlet opening to the opening of the chamber. Advantageously, the distribution means include at least one light conductor. The first aspect of the present invention has the advantage that the collector can collect solar energy over a wide range of incident angles without the need for tracking mechanisms. Therefore, the collector efficiently collects and concentrates diffuse light. An advantage of the third aspect of the invention is that the chamber opening of the solar energy conversion chamber approaches a black body so that most of the energy entering the chamber is absorbed within the chamber. The wavelength of solar energy can also be changed in the chamber to allow most of the energy to be absorbed by a photovoltaic cell and converted into electricity. In addition, any heat produced can also be used. BRIEF DESCRIPTION OF THE FIGURES The invention will now be described by way of example with reference to the appended drawings, in which Figure 1 shows a solar energy collector according to the invention, Figure 2 shows a side wall of the collector of the Figure 1 before it is wound in a spiral, Figure 3 shows a cross section of a collector of the invention, Figure 4 shows a cross section of a collector of the invention having baffles in the mouth of the horn, Figure 5 shows a light conductor used in the invention, and Figure 6 shows a conversion chamber of the invention. Similar parts are denoted in the numerical references of similar figures. DETAILED DESCRIPTION OF THE INVENTION The solar collector 1 shown in Figure 1 is a spiral horn, having an entrance opening 2 and an exit opening 3 in a first plane. The lower edge 4 of an inner wall 5 and the lower edge 6 of an outer wall 7 define a second plane 8 perpendicular to the first plane and the inner section of the lower edge 6 of the outer wall 7 with the second plane 8 and the inner section of the lower edge 4 of the inner wall 5 with the second plane 8 lies in the same spiral of 'Golden Section', as indicated by the projection of the inter-section of the lower edge 6 of the outer wall 7 and the inter- section of the lower edge 4 of the inner wall 5 shown by the dotted lines 9 in Figure 1. The inner wall 5 and the outer wall 7 before they are formed in a spiral have the shape shown in Figure 2. The cross section of the spiral is a quadrilateral, the inner wall 5 is shorter than the outer wall 7 so that the upper surface 10 of the horn as shown in Figure 1 is angled towards the center 11 of the spiral. in Figure 2, the height of both the inner wall 5 and the outer wall 7 decrease from the inlet opening 2 to the outlet opening 3. Figure 3 shows a cross-sectional view of the spiral horn of Figure 1. The shape of the spiral can be plotted using the rkfixed function available, for example, in the "Mathemitca" computer package available from olfram Research Inc., PO Box 6059, Shampaign, Illinois 61821-9902, USA, or in the 'Mathcad' package available from Mathsoft Inc , 101 Main Street, Cambridge, Massachusetts, 02142 USA. An incident ray 20 as shown by a dashed line in Figure 3 undergoes multiple reflections on the inner surface of the outer and inner walls 7, 5 of the spiral horn 1 to be directed towards the center or focus 11 of the spiral horn 1. However, a ray of light 27 incident at the same point 23 as the ray 20 in the spiral at a smaller angle of incidence undergoes multiple reflections and is reflected outside the entrance opening 2 of the horn 1. With the insertion of baffles 30 in the mouth 2 of the horn 1, as shown in Figure 4, a light beam 31, as shown by the dashed line, incident at the same point 23 of the spiral horn as shown in Figure 3 , is reflected by the deflector 30 towards the wall 7 of the spiral horn 1 and is finally reflected towards the center 11 of the spiral. In addition, a light beam 32, which in the absence of the baffle, could be incident from the same point 23 on the spiral horn 1 at a smaller angle of incidence, as shown by the solid line in Figure 4, is incident in place of the deflector 30 and is therefore reflected on the surface of the spiral horn 1 from where it is reflected towards the center 11 of the spiral. Thus, the insertion of the deflectors 30 into the mouth of the horn increases the range of angles of incidence of solar energy rays which are reflected towards the center 11 of the spiral. The deflectors 30, as shown in Figure 4, also according to the curve of a spiral, thereby forming a number of spiral horns inside the mouth 2 of the collector horn. Alternatively, instead of the vertical baffles 30 located between a lower surface 12 and the upper surface 10 of the mouth 2 of the spiral collector, a plurality of partial coiled horns can be inserted into the mouth 2 of the spiral horn to form a alveolar construction of small coiled horns within a portion of the collector closest to the entrance opening. The spiral horn 1 can be formed of polished metal, for example, aluminum. However, because the high temperatures reached towards the portion of the spiral closest to the outlet opening 3, a portion of the spiral horn closest to the outlet opening 3 can be formed of a ceramic material. Additionally, a portion of the horn closest to the inlet opening 2, which is subjected to low temperatures that the rest of the horn, may be formed of a plastic material coated with metal to form a reflecting surface. The inlet opening 2 can be covered by a window for absorbing ultraviolet light, for protecting the reflective surfaces of the spiral horn 1 from damage of ultraviolet light, or preferably the horn can be formed of a glass-metal-glass interposition in which the glass layers absorb ultraviolet light. The light emerging from the outlet opening 3 can be directed by known light conductors 40, as shown in Figure 5. As indicated in Figure 5, the light 41, 42 of more than one manifold can be directed. combine by a splice? and? 43 of light conductors 40 for subsequent distribution. The light emerging from the collector 1 can be used in any known method of solar energy conversion, or it can be distributed by light conductors 40, to provide illumination, for example, in a building. The light can be extracted from the light conductor 40 for illumination, by means of a diffuser. The diffuser may be in the shape of a spiral horn, wherein the light of the light conductor 40 is incident on a small entry aperture in the center of a spiral horn and the diffused light diffuses from an aperture of exit at the mouth of the horn. That is, the diffuser can be a spiral horn used in a direction opposite to that of the spiral horn collector. It will be understood that such a diffuser could be connected directly to the solar collector 1 without the use of a light conductor 40. Alternatively, a solar energy converter 50 can be provided as shown in Figure 6. The solar energy converter comprises a chamber cylindrical having an entrance opening 51 in the center of a circular end surface 52. The inner walls of the solar collector can be provided with photovoltaic cells or with thermal energy absorbing means, such as conduits containing a fluid for absorption and single incident energy conversion through the inlet opening 51. Solar energy entering the solar converter via the inlet opening 51 may undergo multiple reflections within the chamber 50 before it is absorbed. In addition, the interior of the chamber 50 can be provided with wavelength converting means, for example, to convert the wavelength of solar energy to a wavelength more suitable for absorption by photovoltaic cells. To maintain the efficiency of the solar cells they can be cooled in a known manner, for example, by a cooling fluid and the energy gained by the cooling fluid can also be used in a known manner. It will be appreciated by the person skilled in the art that the shape of the chamber 50 is not critical and any convenient shape which promotes multiple reflections within the chamber 50 will be suitable. Similarly, the placement of the aperture 51 is not critical . The inlet opening 51 of the solar collector can be connected directly to the outlet opening 3 of the solar collector 1 or the solar collector 1 can be connected to the solar converter 50 by means of light conductors 40. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it refers.

Claims (25)

CLAIMS Having described the invention as above, the contents of the following claims are claimed as property:

1. A solar energy concentrator characterized in that it comprises a spiral horn having an axis perpendicular to a plane of the spiral, the concentrator includes: an inlet opening forming a mouth of the horn, a reflecting surface of internal light of the horn, and a outlet opening at one end of the horn remote from the mouth of the horn, the exit opening is smaller than the entrance opening and the horn is continuously tapered both in the direction of the axis and in the plane of the spiral, between the openings inlet and outlet, wherein the horn is adapted to concentrate, by multiple reflections from the internal light reflection surface of the horn, the incident solar energy within a predetermined range of incidence angles at the entrance opening, so that Concentrated solar energy is emitted from the exit opening.

A solar energy concentrator according to claim 1, characterized in that at least one guideline is provided at the mouth of the horn to reflect the incident light from outside the predetermined range of incidence angles in the predetermined range of incidence angles.

3. A solar energy concentrator according to claim 2, characterized in that at least one directrix is a deflector positioned substantially parallel to the axis of the spiral horn.

4. A solar energy concentrator according to claim 2, characterized in that at least one directrix is a partial spiral horn placed substantially perpendicular to the axis of the spiral horn in at least a portion of the spiral horn closest to the mouth of the horn.

5. A solar energy concentrator according to any of the preceding claims, characterized in that the spiral horn has a substantially quadrilateral cross section parallel to the axis of the horn.

6. A solar energy concentrator according to any of the preceding claims, characterized in that the spiral is a Gold Section Spiral.

7. A solar energy concentrator according to any of the preceding claims, characterized in that the horn is made of metal.

8. A solar energy concentrator according to claim 7, characterized in that the metal is aluminum.

9. A solar energy concentrator according to any of the preceding claims, characterized in that the horn has portions formed of different materials placed along the spiral of the horn, the materials are adapted to withstand the temperatures reached in the respective portions of the horn. collector in use.

A solar energy concentrator according to claim 9, characterized in that a portion of the horn near the outlet opening is made of a ceramic material.

11. A solar energy concentrator according to any of the preceding claims, characterized in that the light reflecting surface is protected by means that absorb ultraviolet radiation.

12. A combination of the solar energy concentrator according to any of the preceding claims, and distribution means in communication with the outlet opening, characterized in that they are adapted to distribute the concentrated solar energy emitted from the outlet opening.

13. A combination according to claim 12, characterized in that the distribution means include at least one light conduit.

A combination according to claim 12 or 13, characterized in that the distribution means include a diffuser for diffusing or propagating at least some of the concentrated solar energy to provide illumination.

15. A combination according to claim 14, characterized in that the diffuser is in the shape of a spiral horn.

16. A solar energy concentrator according to any of claims 1-11, in combination with a solar energy conversion chamber characterized in that it has a chamber opening in communication with the outlet opening of the concentrator, the chamber contains means of energy conversion to convert the concentrated solar energy emitted from the exit opening.

17. A combination according to claim 16, characterized in that the energy conversion means include a photovoltaic cell.

18. A combination according to claim 16, characterized in that the energy conversion means include means of absorbing heat.

19. A combination according to claim 16, characterized in that the energy conversion means include steam generating means.

20. A combination according to claim 16, characterized in that the energy conversion means include a solar oven.

21. A combination according to any of claims 16 to 20, characterized in that at least some of the solar energy is reflected inside the chamber before being incident on the energy conversion means.

22. A combination according to any of claims 16 to 21, characterized in that at least some of the solar energy undergoes wavelength changes within the chamber.

23. A combination according to claim 22, characterized in that the solar energy increases the wavelength by the absorption and / or dissipation of energy.

24. A combination according to any of claims 16 to 23, characterized in that means of distributing solar energy are provided to transmit the solar energy from the outlet opening to the chamber opening.

25. A combination according to claim 24, characterized in that the distribution means include at least one light conduit.