Classifications

• • 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
  • F24S23/82—Arrangements for concentrating solar-rays for solar heat collectors with reflectors characterised by the material or the construction of the reflector
• • 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
  • F24S2023/87—Reflectors layout
  • F24S2023/874—Reflectors formed by assemblies of adjacent similar reflective facets
• • 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
  • F24S25/60—Fixation means, e.g. fasteners, specially adapted for supporting solar heat collector modules
  • F24S2025/601—Fixation means, e.g. fasteners, specially adapted for supporting solar heat collector modules by bonding, e.g. by using adhesives
• • 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

Definitions

• the . present invention relates to the sector of concentrating solar-power plants for the conversion of solar power into thermal, chemical, or electric power.
• the reflecting part of the linear concentrating system is constituted by a series of panels that provide a cylindrical-parabolic reflecting surface, i.e., a surface the right section of which is a parabola, which has the function of concentrating the solar rays on a receiver tube, traversed by a thermovector fluid.
• the receiver tube is thus responsible for conversion - ' of the solar power into thermal power, which is used in turn for producing electric power or for sustaining chemical processes.
• the invention regards in greater detail a thin- mirror reflecting panel with linear parabolic geometry, of the type constituted by a stiff support, applied on which is, for example via an adhesive, a thin ' glass. that constitutes the reflecting surface..
• Panels of this type have been used in the production of concentrating solar-power plants and can be deemed a technical component that is important in exploitation of solar energy in the immediate future.
• cylindrical- parabolic solar concentrators made up of mirrors made- of thermally tempered curved glass having a thickness of 4-5 mm and a parabolic shape, which rest on a lattice structure constituted by hollow tubes arranged according to a lattice, which provides the stiffness necessary .for countering the deforming force due to the action of the wind.
• the panel is then formed by a self-supporting glass and is rested directly upon the underlying structure.
• Solar mirrors of this type present the characteristic of being difficult to handle and brittle so as to requires in some cases reinforcement with glass fibres for improving their mechanical characteristics .
• parabolic reflecting panels referred to as "thin-mirror panels", i.e., constituted by a mirror of .small thickness (approximately 0.85 mm) applied to a stiff support constituted by a sandwich with fibre-glass skins and honeycomb aluminium core.
• this technical solution has proven able to offer a greater manageability and ease of installation, as well as a- greater safety in regard to possible yielding, of the glass, which remains in any case glued to the structural support.
• vacuum-bag technique a process for the production of sandwich mirrors, referred to as "vacuum-bag technique", is currently used.
• the fabric impregnated with resin and deposited on the corresponding mould is enclosed in a bag of polymeric material in which the vacuum is formed and maintained.
• the pressure exerted by the bag and the heat supplied - from outside enable polymerization of the material, which assumes the shape of the mould imposed.
• thin-mirror panels of a known type presents limits in relation to the stiffness offered to deformations induced thermally or by the mechanical action of the wind and of the interaction with the . supporting structures.
• a further limit of known panels is then constituted by the possibility of automating the entire production process.
• a first purpose of the present invention is to provide a thin-mirror panel that will be light and at the same time stiff in regard to thermal and mechanical stresses, reducing the possible points of initiation of cracks in the glass.
• a further purpose is to provide a support for thin-mirror panels that will be compatible with the glass applied and workable using automated techniques.
• Yet a further purpose of the invention is to propose a support for the glass that will ensure high dimensional stability.
• a reflecting panel comprising a mirror made of thin glass applied to a stiff supporting layer formed starting from a sheet-moulding-compound (SMC) material.
• SMC sheet-moulding-compound
• the advantages obtained basically consist in enabling a higher strength-to-weight ratio as compared to the supports already known thanks to the good specific characteristics (i.e., referred to the -density) of SMC materials.
• a further advantage consists in the simplicity of assembly and installation, and hence in the need for smaller workforce.
• SMC materials are made up to a large extent of inert fillers and glass fibres, the availability of which does not substantially depend upon raw materials (for example, ones of petroliferous origin) , which would involve unstable costs and market conditions.
• composition of SMC materials can be readily modified in order to obtain specific desirable characteristics on the basis of the requirements.
• Figure 1 shows in perspective view a reflecting panel ' according to the invention
• Figure 2 shows a cross section of the panel of Figure 1;
• Figure 3 shows a detail of the points of rest of the panel of Figure 1;
• Figure 4 shows the arrangement of two panels according to the invention to form a semi-parabola of the reflecting surface of a solar concentrator with a linear parabolic configuration
• Figure 5 is a schematic illustration of a solar concentrator with a linear parabolic configuration provided with the panels according to the invention.
• a reflecting panel 1 which comprises a supporting layer 2 with parabolic geometry, and a thin glass 3 applied to the concave surface 4 of the support, for example via a layer 18 of adhesive.
• the edges of the glass 3 can be ground in order to limit to the minimum the edge defects and the likelihood of. breaking of the glass. Furthermore, the strength of the thin glass 2, and hence its curving capacity for its application to the support, can be increased through . appropriate methods of thermal or chemical tempering, which are in themselves known.
• the supporting layer 2 is constituted by a stiff layer formed starting from a sheet-moulding-compound (SMC) composite material and comprising 'randomly arranged glass fibres, pre- impregnated with thermoplastic resins.
• SMC sheet-moulding-compound
• the SMC material comprises unsaturated polyester resins, mineral fillers, and glass fibres, in addition to other components, such as catalysts, thickening agents, thermoplastic additives, detaching agents, other minor components, and possible pigments.
• composition of the support 2 may in any case vary according to the applications .
• an SMC with physical and mechanical properties compatible with typical applications . in concentrating solar-power plants can have a weight percentage of glass fibres of- between 30 wt% and 50 wt%, of mineral fillers of between 5 wt% and 30 wt%, and of unsaturated polyester resin of between 20 wt% and 25 wt%.
• the composition of the SMC material with particular reference to the amount of glass fibre, fillers, and resin, significant variations can be obtained in. the chemico-physical characteristics of the finished product according to the various applications.
• a content of glass fibres comprised approximately between 40 wt% and 50 wt%, the dimensional stability of the panel is greater when subjected to the day/night thermal variations that the panel is bound to undergo during use.
• the greater stability of the support 2 in turn improves the compatibility with the mirror made of thin glass since it brings the values of coefficient of thermal expansion of the two parts closer once they have been coupled together, thus limiting possible fractures or cracks of the glass, or deformations of the geometry of the panel.
• the support 2 made of SMC with 50 wt% of fibre has shown a ' coefficient close to 12 x 10 6 /°C, ranging between 10 x 10 6 /°C and 15 x 10 6 /°C.
• stiffening ribs 9 devised in order to increase the stiffness of the support 2 when this is attached in a number of attachment points 8 to a supporting structure 17 of a solar-power plant, for example a concentrator of the type illustrated in Figure 5.
• each panel 1 is provided with four attachment points 8, which are arranged on the convex surface 5 and from which the ribs 9 irradiate.
• the support 3 is obtained by pressing by means of hot forming starting from one or more pre-impregnated sheets of composite . SMC material.
• steel moulds can be used ' of dimensions similar to those of the panels 1 to be obtained, with a considerable reduction in encumbrance and costs as compared to the equipment necessary for the production of supports already known, at the same time maintaining a high productivity.
• the concentrator 14 comprises a distribution along a longitudinal axis X of pairs of panels 11, 12 arranged, respectively, in an internal position, i.e., adjacent to one another, and an external position in the two directions transverse with respect to the longitudinal axis X of ⁇ the concentrator.
• each panel 11, 12 corresponds approximately to one quarter of the arc of a parabola that constitutes the right section of the reflecting surface of the concentrator, and each pair of panels 11, 12 defines a stretch in length of a semi-parabola of the reflecting surface itself.
• the reflecting surface of the concentrator 14 has a transverse aperture L, measuring 5900 mm in length, and a focus F set at 1810 mm from the vertex V of the parabolic surface.
• the reflecting surface does not originate in the axis X of the parabola, but is shifted transversely by 50 mm in so far as the band 15 under the line of the foci F is in the shade, of the receiver tube 16 (constituted, for example, by a tube traversed by a thermovector fluid for conversion of the solar energy into thermal energy) and is thus unproductive.
• the development in the plane of the reflecting surface per unit length comes to correspond exactly to twice the surface of two panels.
• the width of the panels has been chosen as 1600 mm, and the thickness of the panels, including the points 8 for anchorage to the supporting structure 17, may be comprised between 5- and 25 mm, but it is understood that different dimensions may be chosen according to the application.

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

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• 2009
  • 2009-09-18 IT ITRM2009A000476A patent/IT1398366B1/it active
• 2010
  • 2010-09-10 WO PCT/IT2010/000389 patent/WO2011033546A2/en not_active Ceased
  • 2010-09-10 EP EP10773717A patent/EP2478308A2/en not_active Withdrawn

Non-Patent Citations (1)

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