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
  • F24S23/71—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with 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
  • F24S2023/83—Other shapes
  • F24S2023/832—Other shapes curved
• • 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 a solar concentrator.
• the present invention relates to a concentrator of light rays obtained from the full or partial rotation of a profile with respect to an axis, and consequent concentration of the radiation on the surface thus generated.
• Solar power units for energy production usually comprise a certain number of heliostats, installed on the ground able to direct and possibly concentrate solar radiation towards a determined target.
• CPC Compound Parabolic Concentrator
• Figure 1 schematically shows the 2D profile (in two dimensions) of a CPC-type concentrator; in this figure it is evident how the arc A, i.e. one of the two arcs of the profile P, consists of a part of parabola B having the axis C parallel to the direction D, and focus in E.
• Figure 2 is, instead, a schematic - and sectional - representation of the operation of a CPC-type concentrator.
• This type of revolution surface K is normally used in the so-called beam down- type systems.
• the surface K can be approximated by a series of segments (or bands) that approximate the profile and, joined together, give thus rise, in the input section L and in the output section G, to a polygonal profile.
• a CPC-type concentrator proves to be highly efficient, in the same conditions compared to concentrators of other shapes and volumes, when, e.g., it is necessary to collect and concentrate - as mentioned - solar radiation for the production of energy and heat coming from one or more reflection devices (e.g., the heliostats).
• the technical aim of the present invention is to improve the state of the art in the field of solar concentrators.
• Another object of the present invention is to provide a solar concentrator which can be installed on the ground or in any case at a reduced height above the ground and in a non-vertical position as generally required in beam down systems, and therefore substantially at the level of the plane in which the heliostats are located.
• Another object of the present invention is to accomplish the above objects with a simple and economical solution from the constructive point of view.
• Still another object of the present invention is to accomplish the above objects with a simple and economical solution from the installation and maintenance point of view.
• the non-imaging-type concentrator comprises at least one input section of the light rays, at least one reflecting surface of the light rays passing through said input section, and at least one output section suitable for collecting the light rays which pass through the input section;
• the reflecting surface comprises at least a full or partial revolution surface of at least a two-dimensional profile about a first axis.
• the aforementioned profile does not intersect the first axis, and comprises a first stretch and a second stretch arranged in a mirror-like, or substantially mirror-like, manner with respect to a second axis; the second axis and the first axis are perpendicular or incident to each other.
• the reflecting surface comprises a first portion and a second portion separated from each other, which identify an internal reflection space between them, and between which a discontinuity, which defines the aforementioned output section, is provided.
• the first portion and the second portion of the reflecting surface are a revolution surface respectively of the first stretch and of the second stretch of the profile around the first axis, for an angle equal to 360° or less than 360°.
• Figure 1 is a schematic representation of the two-dimensional profile of a CPC concentrator of the known type
• Figure 2 is a two-dimensional schematic representation of the operation of a CPC concentrator of the known type
• Figure 3 is a three-dimensional schematic view of a CPC concentrator of the known type
• Figure 4 is a schematic front view of a beam down-type solar power unit comprising a known CPC-type concentrator Q;
• FIG. 5 is a schematic front view of a solar power unit comprising the concentrator according to the present invention.
• Figure 6 is a schematic front view of the profile of the concentrator according to the present invention.
• Figure 7 is a schematic front view of the concentrator according to the present invention, generated by the revolution of the profile of Figure 6;
• Figure 7 A is an axonometric view of the concentrator of Figure 7;
• Figure 8 is a schematic front view of the profile of the concentrator according to another embodiment of the invention.
• Figure 9 is a schematic front view of the concentrator, generated by the revolution of the profile of Figure 8.
• Figure 10 is a schematic front view of the profile of the concentrator according to another embodiment of the invention.
• Figure 11 is a schematic front view of the concentrator, generated by the revolution of the profile of Figure 10;
• Figure 12 is a schematic front view of another type of solar power unit comprising the concentrator according to the present invention.
• Figure 13 is a three-dimensional view of the concentrator according to the invention, in another embodiment
• Figure 14 is a front view of the concentrator of Figure 13;
• Figure 15 is a plan view of the concentrator of Figure 13;
• Figure 16 is a three-dimensional view of the concentrator according to the invention, in another embodiment.
• Figure 17 is a plan view of the concentrator of Figure 16.
• Figure 18 is a front view of the concentrator of Figure 16.
• Figure 19 is a front view of another embodiment of the concentrator according to the present invention.
• FIG. 20 is a detailed front view of still another embodiment of the concentrator according to the invention.
• Figure 21 is a detailed front view of a further embodiment of the concentrator according to the invention.
• a solar concentrator according to the present invention is indicated as a whole with the reference number 1.
• the solar power unit 2 comprises a plurality of heliostats 3, installed on the ground; the heliostats 3 are conveniently arranged around a system 4 which in turn comprises the aforementioned concentrator 1, so that the light rays 5 collected by the heliostats 3 themselves are reflected towards the aforementioned concentrator 1.
• the system 4 comprises, in addition to a concentrator 1, also a receiver R, which cooperate and interact in the manner better explained hereinafter.
• the system 4 which incorporates the solar concentrator 1, also comprises a tower 6 which has the function of positioning the concentrator 1 itself at a certain height with respect to the plane of the heliostats 3.
• the solar concentrator 1 according to the present invention can also be advantageously used in the context of solar power units 2 wherein it is installed substantially at the same height with respect to the plane of the heliostats 3.
• the concentrator 1 according to the present invention is of the non imaging type, that is to say, functioning according to the principles of non-imaging optics, which has the advantage of optimizing the energy transmission from a source to a receiver, to the detriment of the formation of the image typical of optical systems, which has no relevance in the field of energy transfer.
• the solar concentrator 1 comprises at least one input section 7 of the light rays 5. Through the input section 7, the light rays 5 penetrate inside the solar concentrator 1.
• the solar concentrator 1 comprises at least one reflecting surface 8 of the light rays 5 which pass through the input section 7.
• the solar concentrator 1 also comprises at least one output section 9.
• the output section 9 is opposed to the input section.
• the output section 9 is suitable to convey the light rays 5 which pass through the input section 7 of the concentrator 1 and which are directed, concentrated, towards it.
• the light rays 5 passing through the output section 9 are collected in the receiver R, which then transfers them to suitable means which will transform them into the desired form (for example, thermal, electrical, mechanical).
• the output section 9 constitutes an interface through which the energy of the light rays 5 is conveyed in parts of the power unit 2 in which it can be exploited in the desired manner.
• the receiver R could be constituted by (or could include) a heat exchange membrane wall, a fluid bed wall, the hot zone of a Stirling engine, a spiral tube, or, more generally, any other element or device suitable to collect the energy provided by the light rays 5 and then transfer it where desired, or to transform it into the desired form, without any limitation.
• the receiver R could comprise (or could communicate with) a fluid bed containing sand, diathermic oil or other suitable materials.
• the receiver R may be of any shape and size, without limitations for the purposes of the present invention.
• the reflecting surface 8 of the solar concentrator 1 comprises at least a full or partial revolution surface of at least a two-dimensional profile 10 about a first axis 11.
• the aforementioned profile 10 does not intersect the first axis 11 (see, for a better understanding, Figure 6, wherein the profile 10 and the first axis 11 are schematically shown).
• such profile 10 comprises a first stretch 12 and a second stretch 13.
• the first stretch 12 and the second stretch 13 are arranged in a mirror-like, or substantially mirror-like, manner with respect to a second axis 14.
• At least one of the first stretch 12 and the second stretch 13 consists of an arc of a parabola.
• At least one of the first stretch 12 and the second stretch 13 consists of an arc of a parabola obtained in the manner illustrated in Figure 1, i.e., in the manner in which the arc of parabola profiles are obtained to make the CPC solar concentrators of the known type.
• first stretch 12 and/or the second stretch 13 may have any suitable conformation, even different from the arc of a parabola (e.g. in a straight segment).
• the profile 10 further comprises an intermediate stretch 15, indicated with a discontinuous line in Figure 6.
• the intermediate stretch 15 does not contribute to the realization of the reflecting surface 8 of the concentrator 1 by revolution around the first axis 11.
• the intermediate stretch 15 consists of a fictitious construction line which - by revolution - generates the aforementioned output section 9 which, as mentioned, is in fact open and does not correspond to any physical entity.
• the intermediate stretch 15 connects - albeit in a virtual, fictitious way - the first stretch 12 to the second stretch 13, so as to obtain the aforementioned profile 10.
• the first stretch 12 of the profile 10 consists of an arc of a parabola.
• first stretch 12 and second stretch 13 are conventional, in order to facilitate the understanding of the characteristics of the invention.
• the first stretch 12 of the profile 10 is the one which, in use, is positioned at the height above the plane of the heliostats 3 of the power unit 2.
• the second stretch 13 could have any form suitable for the application; preferably, but not exclusively, also the second stretch 13 of the profile 10 consists of an arc of a parabola.
• the second stretch 13 of the profile 10 may be identical and specular to the first stretch 12, or it may have different shapes and/or different sizes.
• both the first stretch 12 and the second stretch 13 of the profile 10 consist of respective arcs of a parabola, which are identical and arranged specular with respect to the second axis 14.
• the fictitious connection point 16 of the second stretch 13 to the intermediate stretch 15 coincides with the focus of the first stretch 12 made of an arc of a parabola (see, in this regard, again Figure 1 illustrating the construction of a traditional CPC profile). More generally, in case both stretches 12, 13 consist of arcs of a parabola, the focus of each stretch 12, 13 belongs to the other of the stretches 12,13.
• the second axis 14 and the first axis 11 can be perpendicular or, more generally, incident to each other (i.e. forming, between them, an angle different from 180°).
• first axis 11 and the second axis 14 are perpendicular to each other.
• the reflecting surface 8 comprises (or consists of) a (full or partial) revolution surface of the first stretch 12 and of the second stretch 13 of the profile 10 about the first axis 11, and therefore it consists, in fact, of two separate and opposed portions with respect to the second axis 14.
• the reflecting surface 8 comprises (or consists of) a first portion 12a and a second portion 13a separated from each other; moreover, the first portion 12a and the second portion 13a are opposite to the second axis 14.
• first portion 12a is a revolution surface of the first stretch 12 around the first axis 11
• second portion 13a is a revolution surface of the second stretch 13 around the same first axis 11.
• the first portion 12a and the second portion 13a identify, between them, an inner reflection space S.
• the reflecting surface 8 is discontinuous, i.e., between the first portion 12a and the second portion 13a there is an interruption, or discontinuity.
• the output section 9 is therefore defined.
• the revolution of the profile 10 around the first axis 11 can be performed for an angle which can be equal to 360°, or less than 360°.
• the output section 9 of the concentrator 1 (fictitiously) consists of the (full or partial) revolution surface of the intermediate stretch 15 of the profile 10 around the first axis 11 : such revolution, therefore, is performed for an angle which can be equal to 360°, or less than 360°.
• the output section 9 of the solar concentrator 1 (fictitiously) consists of the side surface of a cylinder (in case of complete revolution).
• the output section 9 of the solar concentrator 1 (fictitiously) consists only of a portion of the side surface of a cylinder.
• the output section 9 - due to the revolution of the profile 10 around the first axis 11 - generates a certain volume (i.e., the volume of a fictious rotation solid).
• the receiver R of the solar power unit is therefore installed inside the volume delimited by the output section 9, or at the output section 9.
• the receiver R of the solar power unit is installed inside the volume of the fictitious cylinder delimited by the output section 9, or fictitious cylinder portion, in order to enjoy the concentration effect of the light rays 5.
• the concentrator 1 is therefore characterized by cylindrical symmetry with respect to the first axis 11 (in case of complete revolution); moreover, the concentrator is also symmetrical with respect to the plane 17 generated by the rotation of the second axis 14 around the first axis 11.
• the configuration of the concentrator 1 according to the embodiment of Figure 7 is particularly advantageous and suitable for the installation substantially at the same height of the plane of the heliostats 3 of the power unit 2.
• - and appropriately orientating the heliostats 3 - the reflected light rays 5 travel substantially parallel to the plane of the heliostats 3 themselves, and then they easily pass through the input section 7 of the concentrator 1, reaching the output section 9 with low dispersions.
• the power unit solution that provides the solar concentrator 1 installed at the same level of the plane of the heliostats 3 is particularly advantageous and efficient from the energetic point of view.
• the reflecting surface 8 could also comprise (or be made starting from) a support made of non-reflecting (or not sufficiently reflecting) material, coated with at least one film of reflecting material.
• the reflecting surface 8 could be made starting from a support made of polymeric material (and therefore easily achievable, for example, by moulding) coated with at least one film of reflecting material.
• FIG. 8 Another embodiment of the solar concentrator 1 according to the invention is shown in Figures 8, 9.
• This embodiment differs from the previous one ( Figures 6, 7) in that the first axis 11 and the second axis 14 are not perpendicular, and form, between them, a predetermined angle a other than 90° and 180°, or referable to such values.
• Figure 8 - around the first axis 11 is schematically shown in Figure 9.
• the solar concentrator 1 is still - evidently - characterized by cylindrical symmetry with respect to the first axis 11, while it is no longer symmetrical with respect to a plane parallel to the plane of the heliostats 3.
• the second axis 14 in its revolution around the first axis 11 no longer generates a plane, but rather a conical surface.
• the outlet section 9 (fictitiously) consists of the lateral surface of a truncated cone (or a portion of the lateral surface of a truncated cone, in the case of a not full revolution around the first axis 11).
• this solution is particularly efficient in the case in which it is intended to position the solar concentrator 1 at a different level with respect to the plane of the heliostats 3, obtaining a power unit solution 2 such as the one schematically shown in Figure 5, or as shown in the power unit solution 2 of Figure 12.
• the concentrator 1 is positioned at a height higher than the plane of the heliostats 3, while in the case of Figure 12 the concentrator 1 (which is located, e.g., at a depression) is positioned at a lower level with respect to the plane of the heliostats 3.
• FIG. 10 Another embodiment of the solar concentrator 1 according to the invention is shown in Figures 10,11.
• the intermediate stretch 15 is inclined with respect to the previous version (which is also represented in a discontinuous stretch in Figure 10, for a better understanding).
• first stretch 12 and the second stretch 13 of the profile 10 are no longer symmetrical with respect to the second axis 14, but have different lengths.
• the result of the revolution of the profile 10 of Figure 10 around the first axis 11 is schematically shown in Figure 11.
• the output surface 9 still, fictitiously, consists of the side surface of a cylinder (as in the version of Figures 6, 7); the first portion 12a of the reflecting surface 8, however, is still oriented downwards, as in the version of Figures 8, 9; alternatively, the first portion 12a could also be oriented upwards (as in the solution of Figure 12).
• a cylindrical output section 9 may be more suitable in the case where a circulating fluid is present inside the receiver R (in turn enclosed by the output section 9), or in any case other applications that prefer this kind of geometry.
• a solar power unit 2 comprising at least one solar concentrator 1 having the characteristics previously described, and at least one receiver R installed inside the volume delimited by the output section 9, or provided at such output section 9.
• the solar power unit 2 comprises a plurality of heliostats 3.
• the solar concentrator 1 can be installed substantially at the same height with respect to the plane of the heliostats 3, using a solar concentrator 1 of the type illustrated in Figures 6, 7.
• the concentrator 1 is very simple to build and maintain; moreover, there are no problems related to the pumping, at a certain height, of the fluid that must transport the collected energy.
• the concentrator 1 can also be installed at a different height with respect to the plane of the heliostats 3 - as schematically shown in Figures 5 and 12 - in particular by using a solar concentrator 1 of the type illustrated in Figures 8-11.
• the heliostats 3 of the power unit 2 may be of any shape suitable for the application.
• the heliostats 3 may be parabolic.
• the solution of the parabolic heliostats 3 is usually the preferred one.
• the heliostats 3 could also be flat - which are simpler to construct - such that the projection surface (through the output section 9) of the light rays 5 reflected by the heliostats 3 does not exceed the diameter of the output section 9 itself.
• the concentrator 1 - even within the same geometry of the embodiment of Figures 6-7A - comprises a plurality of elements 18 mutually connected around the first axis 11, and having a slice-shaped conformation.
• the aforementioned slice-shaped elements 18 could be contiguous, so as to obtain a solar concentrator 1 with full revolution around the first axis 11, or they could also be non-contiguous (i.e. with discontinuities between them), so as to obtain a solar concentrator 1 consisting of sectors arranged in the most appropriate manner in relation to the specific application of solar power unit.
• Each one of the aforementioned elements 18 is delimited by the first portion 12a and the second portion 13a opposite to each other of the reflecting surface 8 (having the characteristics already described with reference to each one of the previous embodiments) and also by two side partitions 19.
• Such partitions 19 can be flat or even curved.
• the partitions 19 are not joining elements of the portions 12a, 13a of reflecting surfaces 8; the partitions 19, in fact, do not necessarily occupy the whole section delimited by the aforementioned portions 12a, 13a of reflecting surfaces 8; for example, such partitions 19 could be connected only to one of the two portions of reflecting surfaces, for example the upper or lower one in use.
• the partitions 19 can, in turn, comprise reflecting surfaces, to facilitate the concentration of the light rays inside the output section 9; alternatively, the partitions 19 could comprise - or consist of - portions of the receiver R, which in this case could protrude/extend outwards beyond the output section 9.
• FIG. 16-18 Another embodiment of the concentrator 1 according to the invention is schematically shown in Figures 16-18.
• the solar concentrator 1 is obtained starting from the rotation of the profile 10 around the first axis 11 by an angle which is much less than 360°; in the embodiment shown, such angle is 90°, but it could also be lower, for example 60°, or 30°.
• the concentrator 1 is delimited by the first portion 12a and the second portion 13a of reflecting surface 8, and by two side partitions 19.
• the partitions 19 can be flat or even curved; they could comprise respective reflecting surfaces, to facilitate the concentration of the light rays inside the output section 9.
• the partitions 19 could also be made of an absorbing material of solar energy, integrating and/or replacing the receiver R.
• a solution of this type can be used, e.g., in the case where the heliostats 3 of the solar power unit 2 are located on a steep surface, e.g., a hill or the like.
• the heliostats 3 (which do not obscure each other) can be concentrated only on a certain side with respect to the system 4 of the light rays 5, or, in any case, within a circumscribed area, since it is not possible to arrange them all around it.
• the concentrator 1 comprises an adjustable-type support 20. More in detail, the support 20 can be adjustable in different ways, to position and/or direct the concentrator 1 in space in the most appropriate manner relating to operating conditions of the solar power unit in which it is installed.
• the support 20 can include an upright 21; the concentrator 1 is associated with the top of the upright 21.
• the upright 21 can, in turn, comprise means for translating and/or rotating the concentrator with respect to the support 20.
• the upright 21 may comprise a stem 22, which is slidably and/or rotatably associated with the same upright 21 by interposition of a translation and/or rotation actuator.
• the concentrator 1 can be raised/lowered and/or rotated with respect to the upright 21, so as to reach the optimum position with respect to the operating conditions of the power unit (e.g., with respect to the position of the sun, the heliostats, etc.).
• the concentrator 1 can be connected to the stem 22 at a hinge 23; the hinge 23 can be associated with a respective rotary actuator in such a way as to rotate the concentrator 1 around an axis orthogonal to the upright 21.
• the concentrator 1 can be oriented at will in space, e.g., in such a way as to favour certain heliostats rather than others within the same solar power unit.
• FIG. 20 differs from that of Figure 19 in that the solar power unit 2 comprises a receiver R consisting of at least one coil, in which a heat exchange fluid is circulated, having the coils arranged at the output section 9 and oriented along the axis 11.
• the embodiment of Figure 21 differs from that of Figure 19 in that the solar power unit 2 comprises a receiver R consisting of at least one coil, in which a heat exchange fluid is circulated, having the coils arranged at the output section 9 and oriented orthogonally with respect to the axis 11.
• the invention thus conceived allows to obtain important technical advantages.
• One of the fundamental advantages consists in that it is possible to eliminate the presence of an auxiliary reflector (such as that shown in Figure 4) in order to make the light rays flow inside the input section 7 of the solar concentrator 1.
• the concentrator 1 according to the present invention allows to directly collect the rays reflected by the heliostats 3 without the need for further reflections. Due to its particular configuration, the use of the solar concentrator 1 according to the present invention is particularly advantageous in the case of low power solar power units 2 (and therefore with a relatively small number of heliostats 3): in fact the concentrator 1, thanks to the its particular conformation, can be installed substantially at the same height above the ground to which the plane of the heliostats 3 is located, or even at a different height, but in any case in order to minimize - or eliminate - the energy expenditure that, in traditional power units, is necessary to consider for the pumping of an energy transport fluid, or, in any case, more generally to transport the energy from the point where it is actually collected.
• the solar concentrator 1 can be efficiently exploited in situations in which the heliostats 3 are positioned on a steep surface (e.g. a hill), and then concentrated on a single side with respect to the positioning of the concentrator 1 itself.
• a steep surface e.g. a hill
• the proposed solution is particularly simple and economical from the construction, installation and maintenance point of view.
• the proposed solution of the concentrator 1 if compared to those currently available, is remarkably versatile, in the sense that it can be simply adapted to application situations that are also quite different from each other, still achieving satisfactory results from the energy efficiency point of view.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• 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)
• Photovoltaic Devices (AREA)
• Optical Elements Other Than Lenses (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=61224326

Family Applications (1)

Country Status (2)

Citations (5)

• 2017
  • 2017-10-13 IT IT102017000115968A patent/IT201700115968A1/it unknown
• 2018
  • 2018-10-15 WO PCT/IB2018/057977 patent/WO2019073461A1/en active Application Filing

Patent Citations (5)

Also Published As

Similar Documents

Legal Events