WO2010023528A2 - Système de collecteur solaire - Google Patents

Système de collecteur solaire Download PDF

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Publication number
WO2010023528A2
WO2010023528A2 PCT/IB2009/006613 IB2009006613W WO2010023528A2 WO 2010023528 A2 WO2010023528 A2 WO 2010023528A2 IB 2009006613 W IB2009006613 W IB 2009006613W WO 2010023528 A2 WO2010023528 A2 WO 2010023528A2
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WO
WIPO (PCT)
Prior art keywords
reflector
tracking
receiver
segments
reflector segments
Prior art date
Application number
PCT/IB2009/006613
Other languages
English (en)
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WO2010023528A3 (fr
Inventor
Harry Zvi Tabor
Original Assignee
Harry Zvi Tabor
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Publication date
Application filed by Harry Zvi Tabor filed Critical Harry Zvi Tabor
Publication of WO2010023528A2 publication Critical patent/WO2010023528A2/fr
Publication of WO2010023528A3 publication Critical patent/WO2010023528A3/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S30/00—Arrangements for moving or orienting solar heat collector modules
    • F24S30/40—Arrangements for moving or orienting solar heat collector modules for rotary movement
    • F24S30/42—Arrangements for moving or orienting solar heat collector modules for rotary movement with only one rotation axis
    • F24S30/425—Horizontal axis
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
    • F24S20/20—Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/74—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with trough-shaped or cylindro-parabolic reflective surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/79—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with spaced and opposed interacting reflective surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
    • F24S2020/10—Solar modules layout; Modular arrangements
    • F24S2020/16—Preventing shading effects
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S2023/83—Other shapes
    • F24S2023/838—Other shapes involutes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S30/00—Arrangements for moving or orienting solar heat collector modules
    • F24S2030/10—Special components
    • F24S2030/13—Transmissions
    • F24S2030/131—Transmissions in the form of articulated bars
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S30/00—Arrangements for moving or orienting solar heat collector modules
    • F24S2030/10—Special components
    • F24S2030/13—Transmissions
    • F24S2030/137—Transmissions for deriving one movement from another one, e.g. for deriving elevation movement from azimuth movement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S25/00—Arrangement of stationary mountings or supports for solar heat collector modules
    • F24S25/10—Arrangement of stationary mountings or supports for solar heat collector modules extending in directions away from a supporting surface
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S25/00—Arrangement of stationary mountings or supports for solar heat collector modules
    • F24S25/70—Arrangement of stationary mountings or supports for solar heat collector modules with means for adjusting the final position or orientation of supporting elements in relation to each other or to a mounting surface; with means for compensating mounting tolerances
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/40—Solar thermal energy, e.g. solar towers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/40—Solar thermal energy, e.g. solar towers
    • Y02E10/47—Mountings or tracking

Definitions

  • the present invention relates to the field of solar energy and to the concentration of solar radiation for producing heat and/or electricity. More particularly, the present invention relates to a solar collecting system that concentrates solar radiation onto receivers using solar collectors.
  • a cylindrical reflector as used in single-axis tracking systems, is a portion, of width or aperture W, of a cylinder, defined by its length L, radius of curvature r, which may or may not be constant.
  • Width W is determined by its subtended 'half-angle' (a), as shown in Fig. IA, 'half-angle' (a ) being the angle at equinox noon between edges
  • a light beam parallel to the optical axis is defined as a 'paraxial beam'.
  • a beam coming from a different direction is defined as a 'non-paraxial' beam and the angle between this beam and the optical axis in the plane of the circle of the cylinder is defined as the 'paraxial departure' ( ⁇ ), see
  • Concentration factor (or power factor) Cp is defined as the aperture width W of the reflector divided by the width of the receiver that receives the reflected radiation from the reflector.
  • Many solar collecting systems are known in the art. They generally comprise one or more reflectors or collectors that reflect the solar radiation onto one or more receivers, facing the reflectors. Some collector systems known in the art have reflectors and receivers rigidly mounted together, so that tracking of such collector systems is performed as one complete unit.
  • the frame of this type of collecting system is very expensive and flexible piping needs to be used to convey the fluid heated in the receiver, the piping of which may develop leaks due to the constant movement of the system.
  • paraxial errors Another difficulty found in prior art collectors is related to the paraxial errors, which reduce the sharpness of the solar radiation focused onto the receiver and thereby bring about a reduction in the degree of concentration that can be obtained.
  • the paraxial errors occur when the solar beam is not paraxial with the optical axis of the concentrator. If an incoming beam of light is parallel to the optical axis of a reflector, it can be brought to a sharp focus, when the reflector has the correct parabolic profile. A non-paraxial beam may come to a sharp focus only for one particular paraxial departure angle for which the profile was designed, but will not come to a sharp focus for all other paraxial departure angles. Consequently, a serious deficiency in the performance of the concentrator is produced since the paraxial departure angle varies from hour to hour and from day to day.
  • the non paraxial ray image is wider than the paraxial ray image, thus reducing the concentration factor.
  • the de-focusing error behaves substantially in a similar manner to the aberration error.
  • the aberration error is approximately proportional to the parallax departure angle and to the aperture angle squared.
  • the aperture dimension is reduced by half, so that the gain in concentration is a factor of two. Since the aberration error and the defocusing error can partially or completely overlap, the larger of these errors determines the maximum concentration factor obtainable with this being further limited by the angular size of the solar disc.
  • US 4,159,710 discloses two or more reflectors performing single-axis tracking, reflecting solar radiation onto a horizontally stationed receiver facing downwards.
  • the apparatus can only perform simultaneous tracking for each coupled reflector, and does not enable different tracking for each of the reflectors.
  • the present invention provides a solar collector apparatus, comprising a horizontally-mounted cylindrical reflector, divided along its length into two reflector segments, each having its own axis of rotation.
  • the two reflector segments are produced by dividing the horizontally- mounted cylindrical reflector down its centerline into two equal reflector segments.
  • the two reflectors segments perform novel tracking with different rotation angles about their corresponding axes by use of a trapeze coupling or a mechanism that permits separate tracking. Since the two reflector segments are coupled, preferably only one tracking mechanism (trapezoid or other) is required since the reflector segments preferably have parallel axes.
  • the present invention also provides a stationary preferably flat plate receiver facing downwards, absorbing the solar energy reflected upwards.
  • the receiver preferably comprises a metal absorbing plate, fluid-carrying tubes, thermal insulation and preferably a black material front for maximizing the absorption.
  • a control is provided to direct radiation away from the receiver in the event of danger of overheating of the receiver or during periods of maintenance.
  • the present invention comprises a method of operating a solar collector, wherein solar radiation from the sun is tracked by preferably a single axis tracking mechanism adapted for performing daily (east to west) or seasonal (north to south) tracking, wherein the tracking mechanism enables two reflector segments, produced by dividing a horizontally- mounted cylindrical reflector along its length into two reflector segments, to rotate about their axes at different angular rates for reflecting the sunlight onto the receiver in order to ensure that the reflected radiation falls onto the receiver.
  • the concentration is significantly increased because there are two reflector segments in place of one and the paraxial end de- focusing errors are reduced because each mirror segment has a smaller half-angle.
  • the two reflector segments used are produced by dividing the horizontally-mounted cylindrical reflector down its centerline into two equal reflector segments,
  • the solar collector system of the present invention can be used for converting solar radiation into heat for thermal collectors (e.g. hot water collectors) or for producing electricity using a system that converts heat into electricity or another system utilizing e.g. photo-voltaic cells.
  • the tracking mechanism is a coupling using a trapezoidal linkage for rigidly operating each half reflector.
  • the tracking is performed by two mechanisms for separate tracking of each half reflector.
  • the one-dimensional tracking can be seasonal single-axis tracking the sun elevation, or daily single-axis tracking following the sun from east to west.
  • Fig. 1 is a schematic general view of the cylindrical reflector according to one embodiment of the apparatus;
  • Fig. IA is a schematic front view of the cylindrical reflector according to one embodiment of the apparatus showing a paraxial solar beam;
  • Fig. IB is a further schematic front view of the cylindrical reflector according to one embodiment of the apparatus showing a non- paraxial solar beam;
  • Fig. 1C is an additional schematic front view of the cylindrical reflector according to one embodiment of the apparatus also showing a non- paraxial solar beam;
  • Fig. 2 is a schematic cross- sectional view of the receiver according to one preferred embodiment of the invention used to harness the heat of the sun;
  • Fig. 2A is a schematic cross-sectional view of the receiver according to another preferred embodiment of the invention used to harness the heat of the sun;
  • Fig. 2B is a schematic elevation view of the receiver according to a further preferred embodiment of the invention used to harness the heat of the sun;
  • Fig. 2B 1 is a schematic end view of the receiver shown in Fig. 2B used to harness the heat of the sun;
  • Fig. 2C is a schematic cross-sectional view of the receiver according to an additional preferred embodiment of the invention used to harness the heat of the sun;
  • Fig. 2D is a schematic cross-sectional view of the receiver according to a further preferred embodiment of the invention used to harness the heat of the sun;
  • Fig. 2D' is a schematic cross-sectional view of the receiver according to a still further preferred embodiment of the invention used to harness the heat of the sun;
  • Fig. 3A and Fig. 3B are schematic side views of the reflectors orientation according to a preferred embodiment of the invention;
  • Fig. 3 C and Fig. 3 C" are schematic side views of the half-reflectors orientation according to other preferred embodiments of the invention;
  • Fig. 3D is a schematic side view of the half-reflectors orientation according to a preferred embodiments of the invention
  • Fig. 4 is a schematic side view of the trapezoidal linkage according to another preferred embodiment of the invention
  • Fig. 5 and Fig. 5A are schematic side views of the overlapping of the image rays from the half-reflectors according to a preferred embodiment of the invention
  • Fig. 6 is a schematic side view of the solar collecting system according to one preferred embodiment of the invention
  • Fig. 7 is a schematic side view of supporting mechanism of the solar system according to a preferred embodiment of the invention
  • Fig. 8 is a schematic diagram showing an example of a preferred embodiment of the present invention.
  • tracking refers to a process in which the reflector follow the motion of the sun.
  • the present invention can be better understood by reference to Fig. IA, Fig. IB and Fig. 1C which cover the basic physics which is advantageously exploited in the present invention.
  • Fig. IA shows mirror 2-3 of width W, which concentrates a beam of solar radiation onto a receiver (not shown) in the focal region F.
  • the beam is paraxial and if the profile is parabolic, the concentrated beam forms a thin line of energy on the receiver. However, if the beam is not paraxial, but tilted at an angle ( ⁇ ), an image of concentrated light is formed at F2 (see Fig. IB). Whatever the paraxial departure ( ⁇ ) is, the image always falls on the cc, the circumscribing circle, that passes through the mirror extremities 2 and 3 and the focus F.
  • the center of this circle is at C, C being a geometrical property of the mirror so that if the mirror moves, C moves with it.
  • the central area of the mirror reflects to a point F', not quite at F.
  • F F' is the spherical aberration already referred to.
  • the image at F2 can be brought to the region of F by rotating the mirror about a horizontal axis h which, generally, is just below the center of the mirror (see Fig. 1C).
  • Fig. 1C the position before rotation, see Fig. IB, is shown in dotted lines while the position after rotation is shown in full lines. From Fig. 1C it can be seen that F3 (previously F2) is closer to the mirror than the image F.
  • the distance F F3 is the defocusing error or distance. Note that I3 is the incoming solar beam that is focused at F.
  • the image size will be larger than the image at F due to the angular spread of the rays from the mirror - and the minimum image size occurs when the pane or receiver is approximately in the middle of the defocusing distance.
  • the mirror of width W is preferably divided into two halves of width W/2 each, with the images of both parts overlapping.
  • each half behaves as described herein with substantially reduced parallax and defocusing errors, because of the smaller angular size, resulting in a smaller final image, thereby providing higher concentration and leading to an improved solar collector system.
  • Fig. 2 is a cross-sectional view of the receiver according to a preferred embodiment of the present invention used to harness the heat of the sun.
  • Receiver (14) is a 'flat type receiver' comprising a metal absorbing plate (9) to which one or more fluid-transporting pipes (11) are connected.
  • the receiver can be a metal structure including fluid-carrying tubes, or may be a single elliptical fluid-carrying tube HB, as shown in Fig. 2B (an end view presented in Fig. 2B') or may be a PV panel or other means of converting solar heat to electricity.
  • reference numeral 13B designates connecting pipes connected to pipe 1 IB, the end plates of which are designated as 9B (see Fig. 2B').
  • Reference numeral 12 designates insulation material present at the back of tube HB while the front has the insulation of the air in gap 15B between tube HB and cover window 1OB, preferably curved.
  • fluids that can be used in fluid- transporting pipes (11) are water, thermal heat transfer fluid e.g. thermal oil, motive fluids e.g. n-pentane, iso-pentane, butane, propane, hexane, Terminol LT, Dowtherm J, dodecane, etc.
  • Therminol LT is the commercial name for the alkyl substituted aromatic fluid of the Solutia Company having a center in Belgium.
  • Dowtherm J is the commercial name for a mixture of isomers of an alkylated aromatic fluid of the Dow Chemical Company being centered in the U.S.A.
  • the pipes can be connected to metal absorbing plate (9) so that pipes (11) protrude below the level of absorbing plate (9) as shown.
  • the pipes can be located above or behind metal absorbing plate (9) by connecting pipes (11) to the rear or upper side of absorbing plate (11) so that heat is transferred to the fluid flowing in pipes (11) by heat conduction from metal absorbing plate (9) to the walls of pipes (11) - see Fig. 2B.
  • Heat is extracted from receiver (14) by supplying suitable a fluid through tubes (11).
  • the front side of the absorbing plate receives the solar radiation and is separated from the outside atmosphere by a transparent window (10), spaced, in this example, about two cms from the plate.
  • the rear side of the plate and the edges are covered with thermally -insulating material (12). All the above is encased in a water-resistant box (14) referred to herein as the 'receiver box'.
  • the front side of plate (9) is preferably coated with black material to maximize the absorption of impinging solar radiation.
  • the receiver is preferably coated with a low emittance black coating, known in the art as a 'selective surface coating', to reduce thermal radiation heat loss from the absorbing plate. Consequently, the dominant heat loss is air convection in the air volume between plate 9 and window 10.
  • the black material may comprise any heat resistant paint with a thermal emissivity of about 0.9, whereas, in such a case, most of the heat loss is by thermal radiation from the absorbing plate.
  • box (14A) is mounted substantially horizontally, facing downwards, and solar radiation coming from a concentrating reflector (not shown) enters window (10) of box (14A).
  • the convection loss in the air space is substantially reduced. Due to the combination of preferred use of a selective surface coating and box (14A) facing downwards, the thermal heat loss at any specific temperature (above the ambient temperature) is reduced considerably compared to that in conventional solar water heating systems. Consequently, in the present invention, the thermal efficiency is increased so that the system can operate at higher temperatures.
  • receiver box (14A) can be smaller in size, reducing possible shading and capital costs.
  • PV collectors are used to harness the solar energy to produce electricity
  • PV cells are bonded to the face of the receiver plate in place of the selective surface and the thermal insulation material may be omitted. If needed, a heat-removal fluid is passed through pipes to cool the PV cells.
  • a secondary non-imaging concentrator can be used to concentrate the solar radiation concentrated already by the primary reflectors or collectors of the present invention.
  • Fig. 2C shows a secondary compound elliptical concentrator (CEC) having secondary reflector surfaces 14C which can be used in the present invention to further concentrate the concentrated solar radiation onto the receiver.
  • Figs. 2D and 2D' show a secondary involute concentrator having secondary reflector surfaces 14D and 14D' respectively (Fig. 2D showing e.g. a receiver having one pipe while Fig. 2D' shows a receiver having e.g.
  • FIG. 3A and Fig. 3B illustrates a side view of reflector (22) according to a preferred embodiment of the present invention.
  • Reflector (22) is preferably divided down its centerline (4-7) into two equal parts (17) and (18), each- having its own axis of rotation (20) and (21) for tracking.
  • the receiver (not shown) is placed at focal point (7).
  • the two reflector-halves (17) and (18) behave as the original reflector (22) and the parallax deviation is zero or close to zero i.e. there is no or very little parallax error.
  • Fig 3B shows that each preferred half reflector (17) and (18) of reflector (22) tracks the sun.
  • the rotation of reflector halves (17) and (18) is about their respective axes (20) and (21), located preferably under the center of each half reflector.
  • the axes of rotation 20 and 21 need not be located under the center of mirror elements 17 and 18. Rather, they may be preferably located, as shown e.g. in Fig. SC and Fig. 3C", toward the edge of mirror elements 17 and 18 either below or above respectively the mirror elements on lines passing through the focal point F and center Cj or C£ of circumscribing circles 40 and 41, these circumscribing circles shown for additional clarity in Fig. 3D.
  • axes of rotation 20 and 21 may be placed to coincide with the centers Ci or C2 of circumscribing circles 40 and 41 as shown in Fig. 3D.
  • the mirror elements can be suspended from the axes of rotation using arms 43.
  • Tracking illustrated in Fig 3B, is particularly useful during times when parallax errors start to occur (not at the time of the equinox), and, reference to the previous description will make it apparent to the skilled person in the art that the parallax error obtained by two half reflectors (17) and (18) is much smaller than the error produced by full- aperture reflector (22).
  • the total parallax error is that of a half- aperture reflector and not twice its value. The net result is that the concentration factor that can be obtained is in excess of about 20.
  • each preferred half reflector (17,18) carries out its tracking at a different rate since the reflector halves are wide, so that better overlap of the images is obtained when using different tracking rates. If the reflector halves (17), (18) were narrow, they would track at the same rate (similar to the rate of a Fresnel-type concentrator).
  • Fig. 4 illustrates a side view of trapezoidal linkage (24) according to a preferred embodiment of the present invention.
  • Trapezoidal linkage (24) is rigidly attached to each preferred half-reflector (17) and (18) respectively, the half- reflectors being equal in length.
  • Radial bars (15) and (16), equal in length, connect to half-reflector (17) and (18) respectively at their distal end, and are connected to coupling bar (19) via hinges (13) and (14), respectively, at their rear ends.
  • Bar (19) is preferably longer than the distance between rotation axes (20) and (21) of the half-reflectors, resulting in a different amount of rotation of half-reflectors (17,18).
  • Fig. 5, and Fig 5A illustrate the overlapping of the image rays from preferred half-reflectors (17) and (18) and indicates plane XX, with the minimum image size xx.
  • (33)-(34) is the aberration of the LHS reflector (17).
  • Point (33) lies on the circumscribing circle (37-38) of the LHS half-reflector (17) in the solstice position.
  • point (35) lies on the circumscribing circle (41-42) of the RHS half-reflector (18) (the aberration is two small to see).
  • (D 1 ) is the defocusing error of the RHS half-reflector, while (D 2 ) is that of the LHS reflector.
  • (D 1 ) is the defocusing error of the RHS half-reflector
  • (D 2 ) is that of the LHS reflector.
  • At the winter solstice most of these extreme rays appear concentrated on the LHS (17) of center line (45-46), and at the summer solstice they will appear in the RHS but within the same image area xx.
  • the minimum image size xx is approximately 1/20 the width of the full (double) reflector width W (shown in Fig IA) i.e. by placing a receiver at xx, a concentration factor of 20 is achievable (according to an example of a reflector having half-aperture of 34.5°.
  • Fig. 5 illustrates an example for a system with a reflector half-aperture angle of 34.5° i.e. 17.25° half-aperture for each reflector half. It was found that in order to track a 40° swing of the sun, from equinox to early or late hours of the solstice day (winter, for example, — a similar swing occurs on the summer solstice day), the lower half-reflector should be rotated approximately by 19.5° eastwards (northern hemisphere) while the upper half-reflector should be rotated approximately by 21.5° . For other reflector half-aperture angles, the rotation ratio will be slightly different and the angles and lengths in the trapezoidal linkage will be slightly different.
  • Fig 5 also shows that, in some extreme positions, partial shadowing p-q, of one half-reflector by the other, may occur. This can be reduced by cutting off some parts of the reflectors in the central region, and if necessary, starting with a slightly larger reflector aperture angle. However, since most of the shading occurs in early morning or at night, only a small part (if any) of the half-reflectors need to be cut.
  • Fig 6 and Fig 7 illustrate a side view of the complete solar collecting system and its supporting pillar in detail, according to one preferred embodiment of the invention comprising two half-reflectors (17) and (18).
  • the full line is the equinox position, while the dotted line is the winter solstice position, see Fig. 8.
  • Fig. 8 is presented by way of example only, where each half mirror AM, MB has a total angle of 34.5°, having a width of approximately 1.5m and a length of about 4m.
  • the reflector profile is part of a circle of radius 5m or more precisely a parabolic profile of 2.5 m focal length.
  • Receiver 14 facing downwards and set at an angle in the range 0 - 30° to the horizontal (dependent on the local altitude).
  • Receiver 14 is placed in the focal area 2.5. m distant from M and is held in place by crossbar and stabilizer 51, and is held in place by cross-bar and stabilizer (51) being connected to elements (44) and (49), that slide on pillar (48) and fixed in position by clamps (50), (52).
  • Receiver plate (9) width is 15 cm (see Fig. 2), assuming a concentration factor of 20.
  • Box (14A) has a width of 25cm with transparent window (10) being 3 mm thick low-absorbing glass. The top and sides of box (14A may be curved to reduce shading.
  • the reflector surface of this example has a high-reflectivity coating on a metal base sheet of about 1 mm thickness which is held by five shaped elements 40, 1 m apart, mounted on a tubular support 41.
  • the upper (RHS) half-reflector (18) performs tracking by means of a tracking motor pinion and segment (42).
  • the 4 m long half-reflectors (17,18) are supported on axes (20) and (21) respectively, which rotate with cross bar (43).
  • Cross-bar (43) is mounted on vertical support pillar(s) (48) that are 4m apart in rows.
  • the half- reflectors (17,18) elements may be coupled in order to make-up continuous long mirror elements (complete reflector).
  • the 4 m long receivers have their inlet and outlet pipes connected in series to form a single fluid flow system.
  • Bars (15) and (16) are the coupling bars of the trapezoidal linkage (24), (19) is the link bar and (13) and (14) are pivots.
  • Pillar (48) has a basic element which is about 10 to 12 cm in diameter and can be made, e.g., of galvanized steel tube, standing on the ground. The upper portion is of a reduced diameter, in order to reduce shading on the mirrors.
  • a horizontal side arm (44) that supports the receiver (14).
  • Horizontal cross beam (43) present at an intermediate level provides support for the half-reflector elements (17,18) via the bearings for the rotation axes (20,21).
  • Cross-bar (43) is part of an element that slides on pillar (48) and is locked in position by clamps (47).
  • the construction of this embodiment is designed to allow uniform heights of reflector elements (17,18) to be set (with the aid of a theodolite) so that long rows can be established without the need for precise leveling of the ground, bringing about a cost-saving improvement.
  • the height of receiver (14) is adjustable using clamp (47c).
  • the present invention also considers that two reflector segments produced by dividing a horizontally-mounted cylindrical reflector along its length into two reflector segments even though the segments are not equal in size can also be used in the present invention.
  • the present invention specifically mentions to use of two reflector segments as described herein, the present invention also contemplates the use of more than two reflector segments, e.g. 3, 4, etc. At present, it is considered that two reflector segments provide sufficiently improved performance at a reduced cost of the horizontally-mounted cylindrical reflector solar collector.

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  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Optical Elements Other Than Lenses (AREA)
  • Photovoltaic Devices (AREA)

Abstract

La présente invention porte sur un appareil collecteur solaire comprenant un réflecteur cylindrique monté horizontalement, divisé sur sa longueur en deux segments réflecteurs ayant chacun son propre axe de rotation. De préférence, les deux segments réflecteurs sont produits en divisant le réflecteur cylindrique monté horizontalement par le milieu pour obtenir deux segments réflecteurs égaux. Chaque segment réflecteur effectue un nouveau suivi supérieur à angles de rotation différents autour de son axe spécifique par couplage trapézoïdal ou mécanisme qui permet un suivi séparé. Les deux segments réflecteurs étant couplés, de préférence un seul mécanisme de suivi (trapézoïdal ou autre) est nécessaire puisque les segments réflecteurs ont de préférence des axes parallèles. La présente invention porte également sur un récepteur à plaque statique, de préférence plat, orienté vers le bas, absorbant l'énergie solaire réfléchie vers le haut. De préférence, le récepteur comprend une plaque absorbante métallique, des tubes de transport de fluide, une isolation thermique et, de préférence, une partie avant en matériau noir pour maximiser l'absorption. Une commande est prévue pour changer la direction du rayonnement par rapport au récepteur en cas de danger de surchauffe du récepteur ou durant des périodes de maintenance.
PCT/IB2009/006613 2008-08-25 2009-08-24 Système de collecteur solaire WO2010023528A2 (fr)

Applications Claiming Priority (2)

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US12/197,722 2008-08-25
US12/197,722 US20100043777A1 (en) 2008-08-25 2008-08-25 Solar collector system

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WO2010023528A2 true WO2010023528A2 (fr) 2010-03-04
WO2010023528A3 WO2010023528A3 (fr) 2010-04-22

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US20110030672A1 (en) * 2006-07-14 2011-02-10 Olsson Mark S Solar Collection Apparatus and Methods Using Accelerometers and Magnetics Sensors
US9022298B2 (en) * 2009-08-27 2015-05-05 Reznor Llc Radiant heat reflector and heat converter
US8522772B1 (en) 2011-02-16 2013-09-03 The United States Of America As Represented By The Secretary Of The Navy Tracking system for lightweight solar collector assembly and array
US8657454B1 (en) 2011-12-28 2014-02-25 The United States Of America As Represented By The Secretary Of The Navy Vacuum formed reflector for solar energy
US9175877B1 (en) 2011-01-31 2015-11-03 The United States Of America, As Represented By The Secretary Of The Navy Two-dimensional Fresnel solar energy concentration system
US8479724B1 (en) 2011-03-16 2013-07-09 The United States Of America As Represented By The Secretary Of The Navy Passive cooling system for lightweight solar collector assembly and array
CN106352562B (zh) * 2016-08-19 2019-01-18 广东工业大学 一种线性菲涅尔太阳能聚光集热器的制造方法

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WO2010023528A3 (fr) 2010-04-22

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