WO2010109508A2

WO2010109508A2 - Concentrating solar panel installation with azimuth orientation system

Info

Publication number: WO2010109508A2
Application number: PCT/IT2010/000110
Authority: WO
Inventors: Mario Gaia
Original assignee: Turboden S.R.L.
Priority date: 2009-03-24
Filing date: 2010-03-16
Publication date: 2010-09-30
Also published as: WO2010109508A3; ITBS20090056A1; IT1393496B1

Abstract

The invention regards a rotary concentrating solar panel system, comprising a plurality of cylindrical-parabolic panels (11 ) with a cylindrical parabolic reflecting element (12) and a receiver (13) in the form of a tube for the passage of a thermovector fluid. The said cylindrical-parabolic panels are mounted side by side and fixed firmly to a platform (14) rotating around its axis perpendicular to the ground and controlled to follow the azimuth position of the sun. Along one side of said platform, perpendicular to the longitudinal direction of the panels, at least one additional reflecting surface (18) is fixed or at variable angles to reflect the solar radiation above the panels.

Description

"CONCENTRATING SOLAR PANEL INSTALLATION WITH AZIMUTH

ORIENTATION SYSTEM"

_{* * * *}

Field of the Invention

The present invention refers in general to the solar thermal collectors field and in particular it concerns a system for thermodynamic conversion of the solar energy into electric energy, starting from a group of cylindrical-parabolic solar collectors with an azimuthal orientation system. State of the technique

For the thermodynamic conversion of the solar energy into electric energy the solar radiation needs to be transformed into thermal energy to be conferred to an adequate thermovector fluid at a higher temperature compared to that of the ambient. The thermal energy, then, can be transformed into electric energy by a thermodynamic cycle.

Therefore, to guarantee suitable efficiency of the thermodynamic cycle the thermal energy needs to be obtained at a temperature as high as possible. For this reason the so-called concentration solar collectors are used in which an opportune optical system, the so-called concentrator, send the solar radiation to an element, called a receiver, in which the radiation is transformed into heat, then transferred at a high temperature to the thermovector fluid. The relation between the tapping surfaces of the concentrator and the receiver of said concentration factor, are usually specified by the letter F. The concentration solar collectors can have very different morphologies, the collectors differing both due to the optical mode adopted (reflection or refraction optical systems, systems with continuous or discontinuous optics, systems with punctual or linear concentration, the concentration factor, etc.) and for the reciprocal disposition and the shape of the concentrator and receiver.

The most successful solution adopted up to now, indicatively represented in Fig. 1a, uses collectors the so-called parabolic-cylinders placed in line, and in each of which the concentrator is in the form of a parabolic reflecting cylinder 1 , that can be orientated around a horizontal axis parallel with the generatrixes of the cylinder and which concentrates the solar radiation on a metal receiver tube 2 run through by a thermovector fluid. The tube 2 -Fig. 1b- is usually provided with a covering 3 with a high absorption coefficient, also protected on the outside by a glass tube 4 that limits both the radiative and convective losses. This type of collector can be classified as being provided with linear concentration in that the deviation of the radiation for concentration purposes takes place only in the orthogonal plane of the generatrixes of the cylindrical trajectory and in the fact that the deviation of the radiation is reached by the reflection of a continuous reflecting surface.

The thermovector fluid that transports the heat from the receiver tube 2 towards the thermodynamic cycle for a subsequent conversion of the thermal energy into electric energy is normally diathermal oil or a mixture of molten salts. A group of solar collectors with cylindrical- parabolic concentrators form a distributed system, in that the collection of solar energy under the form of thermal energy takes place in a distribution form in the entire solar field.

Opportune piping must then carry the hot thermovector fluid to the conversion system in electric energy. One of the problems of the system just described is the necessity to space the successive lines of collectors to limit the effects of the shadows between one line and the other.

Furthermore, according to the arrangement of the lines of collectors (North-South rather than East-West), a not optimal gathering at an angle of incidence in some hours of the day and depending on the season of the year is had.

Therefore a solution was put forward, as shown in Figs. 2a and 2b that envisages the assembly, by means of supports 5, two or more collectors on a rotating platform 6 that allows the generatrixes of the orthogonal trajectory concentration 1 to be kept in the direction of the solar radiation. The concentrators are furthermore each prone to rotation around an axis 7 parallel to its generatrixes, so they are kept orthogonally to the incident radiation. However, also in this case, the successive lines must however be kept apart, to avoid the loss due to shadows and consequently their installation requires the availability of wide surfaces. Furthermore, this system foresees separate orientation mechanisms 8, 9, respectively for the platform and for the collectors, with the relative costs and, in addition, in the case of strong winds the collectors are very exposed to the action of the wind with the risk of suffering damages. Object and Summary of the Invention The object of this invention is to avoid the drawbacks complained about above by a concentration solar collectors and variable orientation system that allows: gathering as best one can the solar radiation and ensure the best performance of the system in every hour of the day and apart from the azimuthal position of the sun, eliminating, or at least drastically limiting the shade zone between the contiguous collectors so as to increase their exposure to the sun, minimizing wind action on the collectors, and innovating on the whole the orientation system, reducing the production, running and maintenance costs of the system.

According to the invention, this object is reached basically with the collocation of a plurality of solar cylinder-parabolic collectors on a turning platform, placed in parallel, tightly drawn side by side, causing a rotation of the platform around a vertical axis, so as to constantly maintain the generatrixes of the cylinder-parabolic surfaces parallel to the azimuthal direction of the sun, and associating said collectors to a structure with one or more reflecting surfaces positioned to tap in addition and reflect the solar light onto the collectors.. Advantageously, the cylinder-parabolic collectors, which form the active part from the point of view of the utilization of the solar energy, used according to the invention and in that they are fixed to the platform, appear easy to make and less expensive compared to the traditional ones, analogous mobile cylinder-parabolic collectors and less exposed to the action of the wind. Furthermore, the system requires a single orientation mechanism, the azimuthal one, not many separate mechanisms for each collector as in the known technique, so it is easier to control. Also worthy of note is that the use of the available surfaces of the ground become better compared to a field of heliostats or parabolic discs and, compared to the occupied surfaces, the performances are better. The interface compared to the ground is limited to a single foundation, whilst, on the other hand, in the traditional systems the alignments and the compensation of the differences of level can be laborious and costly to carry out. The vulnerability compared to the objects dragged by the wind and/or compared to vandalisms becomes less compared to the systems anchored to the ground.

In short, what is proposed by this invention can be considered as a system simple to make and to install. Brief description of the drawings The invention will however be illustrated in greater detail in the description that follows made in reference to the enclosed schematic and not limiting drawings, in which:

Figs. 1a, 1 b and 2a, 2b are indicative of the prior art referred to above; Figs. 3a and 3b show, respectively, a perspective view and a side view of a first embodiment of a solar collectors system according to the invention;

Figs. 4 and 5 show two further forms of solar collectors according to the invention; Figs. 6a, 6b and 6c show forms of the system using moveable means of reflection should there be wind;

Figs. 7a and 7b show a particular support for the rotation of a platform;

Figs. 8a and 8b show the diagrams of other forms of the thermodynamic conversion of the system. Detailed Description of the invention

The system proposed here comprises a plurality of concentrated solar collectors 11 preferably the cylinder-parabolic type.

Each collector therefore comprises a concentrator in the form of a cylindrical parabolic reflecting element 12 and a receiver 13 in the shape of a tube inside of which flows a thermovector fluid. The reflecting element

12 has a concave internal wall, a convex external one and a generatrix one. The receiver 13 is provided with a coating with a high absorption coefficient, protected by a tube in a transparent material, such as glass, as described in connection with Figs. 1 and 2. The receiver 13 is positioned parallel to the parabolic element, facing the concave wall of this element and carried by it by supporting arms.

According to the invention, and as shown in Figs. 3a and 3b, the collectors 11 are mounted adjacent to each other on a platform 14, with the external wall of each parabola attached to the latter.

The platform can rotate around its perpendicular axis X, by means of an actuator 15 and control devices not shown, so as to constantly have the generatrixes of the cylinder-parabolas (that is the receivers 13) basically parallel to the azimuthal direction of the sun. The platform has a rear side 16, perpendicular to the longitudinal direction of the collectors, which is positioned and maintained on the opposite side compared to the morning and evening position of the sun, and a front side 17 opposite to it. On the rear side 16 at least an additional reflecting surface 18 is provided, which is placed with a slope angle 19 that can be fixed, that is, not depending on the zenithal position of the sun, or variable based on the zenithal position of the sun. In this second case, each additional reflecting surface 18 will be mounted and prone to angular rotation with a constraint hinge 19' between the same reflecting surface and the platform. In Figs. 3a and 3b there is represented a first embodiment with a single reflecting surface 18. In Fig. 4 the reflecting surface 18 is divided up into a group of surfaces18a, almost coplanar. Fig. 5 shows a further embodiment in which the collectors 11 on the same platform can be positioned in groups and have different lengths and where more additional reflecting surfaces 18b are provided and are distinct and positioned on different planes, each staggered one from the other even if they are almost parallel.

To reduce the impact of the wind on the reflecting surfaces in the case of strong winds, means for the rotation of the reflecting surfaces are provided as shown in Figs. 6a, 6b and 6c, where for simplicity only the platforms 14 without collectors 11 are shown. In particular the reflecting surfaces in Fig. 6a, under the thrust of the wind can turn around a hinge 19' to move into a horizontal position and close itself on the collectors or turned back 180° compared to them. Otherwise, as shown in Figs. 6b and 6c, every reflecting surface 18c turns on a basically vertical rotation axis 20, that divides the surfaces into two parts 21 , 22 so that one of them is subjected to less aerodynamic thrust than the other. For this purpose, one of said two parts 21 can have, for example, openings 23 (Fig. 6c), or less space (Fig. 6b), to allow the rotation of each reflecting 18c under the thrust of the wind. Furthermore, although not shown, a mechanism could be provided that allows every reflecting surface 18c to turn should there be a wind, and return in position when the wind drops.

In each embodiment, each additional reflecting surface 18a, b and c can be provided with a variably inclined top wing 118 according to the position of the sun so as to reflect as much as possible the solar radiation on to the collectors.

The platform can be constrained to a ground foundation 24 by a support 25 and turn compared with it thanks to a bearing or a roller center plate 26, according for example to the usual technique for the jibs of a crane. The bearing or fifth wheel can be positioned in proximity of the platform or in proximity of the foundation 25, or in an intermediate position (Figs. 7a, 7b).

The thermovector fluid circulating and which heats up in the receivers 13 associated with the cylinder-parabolas 12 and channeled by at least two tubes, one delivery 27 and one return 28 and with the help of at least one pump P, in a position on the rotation axis X of the platform and here, through two rotating joints 29 is carried to a part of the system 30 fixed to the ground.

The part on the ground comprises a power conversion system 31 , a system releasing the heat to the ambient 32 and a thermal accumulation system 33, if needed, according to the diagram in Fig 8a. Fig. 8b shows an analogous diagram to the one in Fig. 8a, but in which all the equipment is found on board the platform and turns with it. The power conversion system 31 , in relation to the temperatures and to the power installed, will preferably be a ORC (Organic Rankin Cycle) type. The diagram indicated, forms a preferential solution, but does not exclude other solutions. In the figures all the accessories normally present in this type of circuits, for example valves, drainage, buffer tanks, expansion tank, etc, are not indicated. Furthermore the power production system can also be fed by a group of platforms instead of only one, so as to have greater power and consequently less specific cost.

Claims

"CONCENTRATING SOLAR PANEL INSTALLATION WITH AZIMUTHORIENTATION SYSTEM"* * * *C L A I M S

1. A rotary concentrating solar panel system, comprising a plurality of cylindrical-parabolic panels (11) with a cylindrical parabolic reflecting element (12) and a receiver (13) in the form of a tube for the passage of a thermovector fluid, characterised in that said cylindrical-parabolic panels are mounted side by side and fixed firmly to a platform (14) which rotates around an axis perpendicular to the ground and is controlled to follow the azimuth position of the sun, and in that along one side of said platform, perpendicular to the longitudinal direction of the panels, at least one additional reflecting surface (18) is fixed and extends upwards to reflect the solar radiation above the panels.

2. A solar panel system according to claim 1 , characterised in that one additional reflecting surface (18) shared by all the panels (11 ) is fixed to the platform (14)

3. A solar panel system according to claim 1 , characterised in that more additional distinct reflecting surfaces (18a), basically coplanar to each other are fixed to the platform (14).

4. A solar panel system according to claim 1 , characterised in that several additional reflecting surfaces (18b) placed at different levels, staggered one from the other according to the longitudinal direction of the panels and basically parallel to each other, are fixed to the platform.

5. A solar panel system according to claims 1-4, wherein each additional reflecting surface (18, 18a, 18b) is fixed firmly to the platform with a fixed slope angle (19).

6. A solar panel system according to claims 1-4, wherein each additional reflecting surface (18, 18a, 18b) is variably sloped to rotate on a horizontal axis hinge depending on the zenith position of the sun.

7. A solar panel system according to any of the previous claims, wherein each additional reflecting surface is equipped at the top with at least a wing which can be variably slanted according to the position of the sun.

8. A solar panel system according to any of the previous claims, wherein means for the rotation of the additional reflecting surfaces are provided when subjected to an aerodynamic thrust and to restore their positions as said thrust reduces.

9. A solar panels system according to claim 8, wherein each additional reflecting surface is susceptible to rotation around a horizontal hinge until it arrives at a horizontal position over or distant from the panels.

10. A solar panels system according to claim 8, wherein every additional reflecting surface is movable at an angle around a vertical axis, said reflecting surface being configured with two asymmetric parts with regard to said axis to offer resistance, one less than thecother, to the aerodynamic thrust.

11. A solar panels system according to claim 10, wherein the rotation axis divides the additional reflecting surface into two parts, one of which has less surface than the other.

12. A solar panel system according to any of the previous claims, wherein the thermovector fluid heated in the cylinder-parabola is conveyed to a thermodynamic conversion system.

13. A solar panels system according to claim 12, wherein the thermodynamic conversion system is fixed to the ground and is connected to the solar panel receivers on the platform by means of rotating joints.

14. A solar panels system according to claim 12, wherein the thermodynamic conversion system is on board the platform and turns with it.

15. A solar panels system according to claim 12, wherein the thermodynamic conversion system is fed by several solar panel systems conforming to the previous claims.