Device for storage of thermal energy of solar origin based on multiple reflections

Abstract

1. A device (1) for the storage and transfer of solar-derived thermal energy, comprising: a containment casing (2) having an irradiation opening (10) configured to allow the entrance of incident solar radiation into an irradiation area (350) defined within the casing (2); a layer of flowable particles (3) received within the casing (2); and at least one reflective and / or re-emitting surface (701, 702, 703) disposed within the irradiation area (350) and configured to reflect solar radiation entering through the irradiation opening (10) directly onto a freeboard (35) of the layer of particles (3) or onto another reflective and / or re-emitting surface of the irradiation area (350).

Description

[Technical field]

[0001] explanation FIELD OF THE PRESENT ART The present invention relates to an apparatus, a plant and a method for the storage and transmission of thermal energy of solar origin.

[0002] In particular, the invention relates to the field of devices for the storage of thermal energy using beds of flowable particles.

[0003] technical level Plants for the production of electrical energy starting from thermal energy associated with concentrated solar radiation are known. Some of these plants are based on so-called fluidized bed devices that receive solar radiation. Fluidized bed devices generally include an optical system of the "beam down" type configured to concentrate the solar radiation from above on a layer of fluidized solid particles that acts as a store of thermal energy. Such energy can then be used for industrial applications in a direct form or in a deferred manner, converted into electrical energy.

[0004] The optical system mentioned above relevant to this type of plant is configured in one or more fields of heliostats placed on the ground, which transmit the solar radiation onto a secondary mirror placed at a high altitude relative to the fluidized bed receiver and reflect the concentrated radiation inside the receiver itself.

[0005] Some of the biggest problems with the above plant configurations are actually related to the optical systems associated therewith.

[0006] In particular, the above-mentioned secondary mirrors of known technology can only operate at a limited maximum temperature (usually up to about 200 °C), which imposes restrictive constraints on the solar current that can be concentrated on it, requiring extended reflecting surfaces if the currents are equal. Such reflecting surfaces, and the relative structures for lifting and supporting them at high altitudes, must be devised to withstand the intrusion of strong winds, which, for this reason too, has a considerable impact on the plant costs. Moreover, in some locations where the winds are particularly strong, the use of "beam-down" optical systems is prevented.

[0007] Another criticality of the known plant concerns the energy efficiency of the above-mentioned system for collecting solar radiation. In particular, the secondary mirror has an assessable reflection efficiency of 80% to 95%, depending on the materials used and the characteristics of the reflective surfaces employed.

[0008] Moreover, the subreflectors of the known technology "beam-down" optical systems contain additional problems of a practical nature, negatively affecting the ability to concentrate the solar energy inside the receiver: in particular, they suffer from potential assembly inaccuracies, the possibility of local deformation due to thermal distortion, non-perfect planarity of the reflecting surface, the need for complex maintenance procedures, fouling phenomena carried out at high altitudes, and deformations due to wind push-in and / or climatic variations. Summary of the Invention

[0009] The technical problem addressed and solved by the present invention is then to provide an apparatus, a plant and a method for the storage and transmission of thermal energy of solar origin that makes it possible to overcome the above-mentioned drawbacks with reference to the known art.

[0010] The above technical problem is solved by an apparatus according to claim 1 and a method according to claim 21.

[0011] Preferred features of the invention are set out in the dependent claims.

[0012] The present invention provides an apparatus, plant and method based on a bed of flowable particles that is exposed to solar radiation after reflection of the solar radiation on one or more internal walls or surfaces, belonging to or housed in a casing that contains the bed itself.

[0013] In particular, the solar radiation is concentrated by a field of heliostats arranged on the ground and enters the receiver device through an opening, which is preferably made in a side wall of the abovementioned casing. The solar radiation entering through the opening strikes one or more internal walls arranged in the free area of ​​the particle bed, i.e. located above its freeboard. Such internal walls have reflective and / or re-radiating surfaces configured to receive the incoming concentrated solar radiation and to reflect it towards the particle bed both directly and indirectly, after multiple reflections on other internal surfaces.

[0014] The portion of the energy that is not reflected to the inner wall is absorbed by the inner wall. In a preferred embodiment, the transmission of such absorbed energy to the external environment is prevented due to the use of materials or thermal insulation measures associated with, and possibly integrating parts of, the wall itself. In this way, the reflecting surface increases its own temperature and reradiates thermal energy towards the layer of particles both directly and indirectly through reradiation between other inner surfaces.

[0015] In other words, the open or irradiated area bounded by the upper surface or freeboard of the layer of particles and by the inner walls of the device located above the surface of said layer acts as a radiation cavity, the surface reflecting and re-radiating the incoming solar radiation directly or indirectly towards the layer of particles according to its specific properties.

[0016] Due to the high thermal diffusivity of the fluidized bed, the energy reflected, and possibly re-radiated, by the walls is transmitted to the entire mass that makes up the fluidized bed, where it can then be contained and stored until further use.

[0017] In a preferred embodiment, the fluidized bed is constituted by solid particles, preferably having a higher absorbance value than the reflective walls, in order to promote rapid transfer of the energy reflected and possibly re-radiated by the walls towards the fluidized bed itself.

[0018] In a variant embodiment, the fluidized bed may consist of particles made of sand or other granular material.

[0019] In a preferred configuration the layer particles reach a maximum temperature, preferably ≧620° C.

[0020] In a preferred embodiment, the reflective surface has high resistance to high temperatures, preferably above 1000° C., and / or a higher reflectivity than the particle layer, preferably higher than 60% when calculated with reference to standards ASTM G173 and ISO 7668.

[0021] The bed of particles is fluidized by a system for supplying and distributing a fluidizing gas, usually air.

[0022] The fluidization can involve a specific working area of ​​the bed or the entire bed of particles. Advantageously, the fluidization system can provide several fluidization units that can be operated independently of each other.

[0023] In a variant of the embodiment, the device can provide additional heat supply for the bed of particles with a heating component, such as an electrical resistor, a heat pump or a dedicated heat exchanger, in particular immersed in the bed itself. Such a dedicated heat exchanger can provide for the circulation of air or another working fluid in a tube bundle or equivalent element.

[0024] In an alternative embodiment, an additional heating component, for example an electrical resistor, can be provided to supply thermal energy to the bed of particles by heating the fluidizing air flowing into the bed itself.

[0025] Advantageously, said heating component and / or the additional heating component can be supplied directly or indirectly by a source of electrical energy that is preferably available in excess, i.e. remaining, with respect to the needs of the user.

[0026] In these embodiments comprising a heating component, the thermal energy stored in the layer of particles can result from two contributions: a primary energy, i.e., the contribution of solar radiation concentrated by the optical system and absorbed by the layer itself, and a secondary energy, i.e., the contribution of electrical energy converted into thermal energy by the heating component described above.

[0027] Such an embodiment is particularly advantageous when there is a need to ensure greater availability of thermal energy under any weather conditions to supply industrial processes that require continuity.

[0028] It will then be seen that the invention makes it possible to eliminate the need to use optical systems of the "beam down" type, as explained with reference to the known art, by overcoming the criticalities associated therewith. In particular, the device, plant and method of the invention are particularly effective for ensuring greater collection efficiency, plant simplification and cost reduction.

[0029] In a simultaneous or delayed manner, the thermal energy stored in the layer of particles can be converted into electrical energy, used as thermal energy or even used in such two forms in a combined flexible manner.

[0030] The devices, plants and methods of the invention can then be used for the programmable generation of electrical energy, for the regulation of electrical networks and / or for thermal energy for other users.

[0031] The device of the present invention can be configured as modular units that can be multiplied according to the specific needs for continuous (24 / 7) generation of electrical and / or thermal energy in service of community and industrial plants.

[0032] The thermal energy stored in the bed of particles can also be used directly via a heated fluidizing gas exiting the bed itself.

[0033] Heat exchange means may be provided configured to recover and / or disperse thermal energy from said reflective and / or re-radiating surfaces if the temperature reached thereby is such that it changes its state or impairs its function.

[0034] The present invention represents an environmentally friendly, durable, effective and inexpensive alternative to current systems for the production of solar-derived thermal or electrical energy.

[0035] Further advantages, features and modes of use of the present invention will become apparent from the following detailed description of some embodiments thereof, given by way of example and not of limitation. [Brief description of the drawings]

[0036] With reference to the figures in the accompanying drawings, [Figure 1] 1 shows a schematic assembly representation in side and partial longitudinal cross-sectional view of an apparatus for storing and transferring thermal energy according to a first preferred embodiment of the present invention, highlighting the interaction between the apparatus itself and its associated system for collecting solar radiation. [Diagram 2] 1 in a top view. [Diagram 3] FIG. 2 shows an enlarged view in side and partial longitudinal section of a device for the storage and transfer of thermal energy according to a second preferred embodiment of the present invention, by highlighting its “glossy” type reflection mode. [Figure 4]FIG. 13 shows an enlarged view in side and partial longitudinal section of a device for the storage and transfer of thermal energy according to a third preferred embodiment of the present invention, providing a "diffuse" type reflection mode.

[0037] The above diagrammatic representations are meant merely as an example, and components and distances are not necessarily shown to scale.

[0038] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and variants of the invention are explained below, which are illustrated with reference to the figures above.

[0039] Similar elements are designated by the same reference numbers in the several figures.

[0040] In the detailed description that follows, additional embodiments and variations relative to those embodiments and variations already addressed in the specification itself are illustrated, limited only to the differences from those already illustrated.

[0041] Furthermore, some of the embodiments and variants described below are likely to be used in combination where compatible.

[0042] With reference to FIG. 1, a device for the storage and exchange of thermal energy of solar origin, or receiver, according to a first preferred embodiment of the invention, is indicated generally at 1.

[0043] The device 1 of this embodiment is intended to be inserted into a plant for energy production, possibly including multiple devices such as those discussed in this specification.

[0044] 2, the device 1 is advantageously associated with an optical system for collecting solar radiation, generally indicated with 500 and configured to concentrate the incident solar radiation on the device 1 (or on a plurality of devices such as those considered herein). In particular, the optical system 500 may comprise a plurality of heliostats 501 or equivalent reflective optical means arranged on the ground and suitable for collecting the incident solar radiation and deflecting / concentrating it on the device 1, in particular on a common focal point F in this example.

[0045] The heliostats 501 may be organized, for example, in subfields arranged according to cardinal directions.

[0046] In the configuration shown, the device 1 is positioned above the resting surface of the heliostat 501 so as to receive concentrated solar radiation thereby according to a "beam up" configuration. The device 1 is therefore supported at high altitude by a structure, for example a metal structure, shown diagrammatically and indicated with 800.

[0047] Now, with reference to the enlarged view of Figure 3, some components of the device common to some of the embodiments illustrated herein are illustrated. The device illustrated herein, further indicated at 1, firstly comprises a containment casing 2 having or defining an internal compartment 20, suitable for containing a layer 3 of flowable particles therearound, as will be described shortly. The casing 2 may have a polygonal, for example cubic or parallelepiped, or cylindrical shape. In the present example, the casing 2 has an upper wall, i.e. top 21, a side wall, i.e. skirt 22, and a lower wall, i.e. bottom 23.

[0048] The casing 2 is mounted so as to thermally insulate the compartment 20 from the outside.

[0049] The casing 2 may have a multi-layer structure.

[0050] With regard to the shape of the device 1, and in particular its casing 2, it is possible to define a longitudinal direction L, which in this example is vertical, and a transverse direction T in a plane perpendicular to the longitudinal direction L, which in this example is horizontal.

[0051] The casing 2 has an irradiation opening 10. In this embodiment, the reflector 501 described above concentrates the incoming solar radiation so that it actually flows into or near such opening 10. Advantageously, as mentioned above, the radiation is concentrated at a single focal point F. The mutual position of the receiver device 1 and the field heliostat, which makes the focal point F correspond to the opening 10, makes it possible to reduce to a minimum the size of the opening itself and, consequently, to reduce radiation losses and losses due to natural convection through it.

[0052] Generally speaking, the configuration is such that radiation is transmitted within the compartment 20 .

[0053] In this embodiment, the opening 10 puts the internal compartment 20, and thus the layer 3 of particles contained therein, in direct communication with the external environment. In particular, during use, the opening 10 does not have any closing or shielding means, such as, for example, a transparent window. In other words, the device 1 is configured to operate without closing or shielding means. During periods of non-operation, the opening can be closed again by removable and appropriately insulated means for protecting the system and eliminating or reducing the dispersion of thermal energy to the external environment.

[0054] Near said opening 10, a component, for example a shield or barrier, can be arranged, which tends to limit the penetration in the device of air currents or wind coming from the external environment, without preventing the concentrated radiation from penetrating into the device itself. Furthermore, around the opening 10, an additional optical device can be provided, for example in the form of a CPC (Compound Parabolic Concentrator), known per se in the state of the art, making it possible to recover the whole or part of the concentrated solar radiation, which would otherwise leak outside the opening 10 itself.

[0055] There may also be provided an embodiment in which the opening 10 is shielded, even during operation, by a transparent window or other equivalent means.

[0056] In this example, the opening 10 is shown as being located in a side skirt 22 of the casing 2, near the top wall 21, but such representation is meant to be exemplary. The opening is limited by a lower edge 230.

[0057] Preferably, the freeboard 35 of layer 3 of particles is lower than lower edge 230 under both static and operating fluidized conditions.

[0058] Preferably, the opening 10 is located in a free area or free space 350 of the compartment 20, bounded below by the freeboard 35 of the particle layer, laterally by the upper part of the skirt 22 and above by the wall 21. Such an area 350 can be defined as the irradiation area.

[0059] The layer of flowable particles 3 is of the granular type formed by solid particles.

[0060] The types of granular material preferred for the layer of particles of the device 1 are those with thermal properties having high thermal capacity and diffusivity. An example of a preferred granular material is river sand, which, apart from having said thermal properties, has a natural rounded shape of the particles which minimizes the phenomenon of mutual abrasion of the particles.

[0061] The inner walls of the casing 2 standing above the layer of particles 3, even when fluidized, are directly or indirectly exposed to the solar radiation concentrated by the heliostats 501. Such walls of the irradiated area 350 have a reflective surface exposed in the compartment 20 made of materials and / or treatments that can have different types of reflective properties, as described below. ■Specular - The surface reflects light in a single direction. The outgoing radiation direction is at the plane of incidence and the angle of reflection is equal to the angle of incidence. ■ Diffuse - The surface reflects light equally in all directions, light reflection is independent of direction, light reflection is independent of direction and entry / entrance surface. ■ Glossy - The surface has a mixed behavior ranging from specular to diffuse reflection.

[0062] In the first embodiment of Fig. 1, an inclined inner wall 701 is provided, which receives the concentrated solar radiation directly, has reflective and / or re-radiating surfaces, operates in a specular mode, and is identified with 701. The arrangement is such that the incident solar radiation is almost completely reflected at the freeboard 35 of the layer 3, depending on the reflective area corresponding to the cross-section of the casing 2.

[0063] In the second embodiment of FIG. 3, the wall schematized by the angled shield 702 has a "glossy" optical behavior.

[0064] In the third embodiment of Fig. 4, the "diffusing" behaviour is provided by a reflective and / or re-radiating surface 703 belonging to the curved wall 24 joining between the side skirt 22 and the top wall 21 of the casing 2. Furthermore, in the configuration of Fig. 4, an additional sloping wall or shield 25 is also provided, having an auxiliary reflective and / or re-radiating surface facing the surface 24.

[0065] 4, a schematic diagram of a system 101 for closing the irradiation opening 10 is shown in the form of a hinged shield in an open position associated with a stage for obtaining concentrated radiation. The device 101 can be closed when there is no need to obtain energy but rather to maintain it.

[0066] Another preferred configuration can provide that the inner walls of the casing 2, in particular the parts of the side skirts 22 and / or the top wall 21 and / or even the junctions between the latter (but also or only) directly have one or more reflective surfaces.

[0067] The surface of the inner wall of the casing 2 may be flat or have a selected profile so as to allow minimization of the total amount of radiation exiting the opening 10 and maximization of the total amount penetrating the fluidized bed, due to the mutual shape factors.

[0068] The reflective and / or re-radiating surfaces are preferably constructed of materials that are resistant to the high temperatures induced by the high heat fluxes they are subjected to, such as ceramic tiles, refractory cement, and / or similar materials.

[0069] In the above configuration, the electromagnetic energy emitted by the inner surface 2 as a whole, i.e. the sum of the radiation emitted and reflected by the surfaces 701-703 due to their mutual view factors, is absorbed by the layer 3 of particles, advantageously chosen with an absorption coefficient higher than that of all surfaces exposed to concentrated solar radiation.

[0070] In particular, the solar radiation reflected by the inner surfaces of the region 350 impinges on the layer of particles 3, either directly or under multiple reflections according to the mutual view factor. Moreover, the inner surfaces absorb the non-reflected energy portion according to their own absorption and reflection coefficients, which causes a temperature increase of such surface, which then re-radiates the solar energy towards the layer of particles, both directly according to the mutual view factor, and indirectly via re-radiation between the inner surfaces.

[0071] Such a configuration determines the device behavior similar to that of a radiation cavity or black body, if the cavity in question is provided with an opening towards the outside with a reduced size with respect to the average size of the cavity itself. Under such conditions, almost the entire concentrated solar radiation incident on the opening is repeatedly reflected, absorbed and re-emitted within the cavity, so that only a very minimal part of it succeeds in exiting, and the solar energy thus captured remains accumulated in the fluidized bed of particles.

[0072] In the configuration of the above figure, the layer of particles 3 is moved by a fluidization means 4 configured to supply and distribute a fluidization gas, in particular air, in the compartment 20. In this embodiment, the means 4 comprises a number of elements 41 for supplying or inflowing the fluidization air, arranged in the lower base 23 of the casing 2, which is the base of the layer of particles 3. The path of the fluidization air in the layer of particles 3 is then, in particular vertical or substantially vertical, from bottom to top. More generally, the fluidization gas inflow takes place according to a longitudinal direction L.

[0073] In this example, a uniform or substantially uniform fluidization of the layer 3 of particles is provided.

[0074] The hydrodynamic regime of the layer 3 allows an effective heat exchange between the particles of its various parts. This is facilitated by the fact that the layer particles are subjected to continuous exchange and recirculation. In use, particles located on or near the freeboard 35 absorb thermal energy by reflected or re-emitted solar radiation and transfer it to other layer particles.

[0075] Heat exchange between particles is driven by convective motion, which is determined by the fluidization regime.

[0076] Variations of the embodiment can provide differentiated fluidization in different regions or parts of the layer 3. The fluidization of some layer regions or parts, or the fluidization regimes selectable therefor, can differentiate the speed, and possibly the flow rate, of the stream of fluidizing air entering the layer 3 of particles.

[0077] The fluidization elements can be arranged uniformly at the base of the layer 3 of particles, as in the present example, or arranged in a differentiated manner.

[0078] There may further be provided fluidization elements which are structurally similar between them and which are optionally differently controlled, for example with respect to speed and / or flow rate.

[0079] The fluidization regime may be of the boiling type and / or generally a regime that promotes convective movement of particles in layer 3 or regions or portions thereof.

[0080] In some embodiment variants, the fluidization regime selected for the entire bed or for its regions or parts can even be of the so-called "jet" type, for example jet, fountain or impulse. Spout-type fluidized beds generally have a hydrodynamic regime characterized by a central jet of fluidizing gas at the base of the same bed, which, due to the strong velocity difference between the particles directly exposed to the jet and the surrounding particles, in fact produces a fountain-like effect in the central part fed by the solids entrained in the lateral parts of the jet, producing a motion entrained by the jet itself and the bed column demanding the (cylindrical) area looking down on it.

[0081] In the layer 3, a heat exchange element 5, in particular a tube bundle, is housed. Such an exchanger can be crossed in series or under selected operating conditions with a working fluid, for example steam or CO2.

[0082] In particular, during a heat exchange phase, which is a phase of using the thermal energy stored in the bed of particles 3, the working fluid can be made to flow through the tube bundle 5 and receive heat from the bed particles. Conversely, during a purely storage phase, the tube bundle 5 can be stationary, i.e. without the circulation of working fluid.

[0083] The storage stage is activated in the presence of the sun. The heat exchange stage, i.e. the stage of transfer of thermal energy to the working fluid, can preferably be activated in the absence of the sun.

[0084] The working fluid leaving the device 1 under the conditions of design temperature and pressure can be expanded in a turbine coupled to a generator for the production of electrical energy or can be used for other industrial purposes, for example for the production of fluid carriers used in industrial processes, especially when thermal energy is required continuously even at very high temperatures. In other words, in the present example, the tube bundle 5 is connected to additional components of the plant, for example one or more turbines, condensers, heat exchangers, pumps, etc., each known in itself.

[0085] The device 1 further comprises means 6 for aspirating the fluidized air that has completed its path in the layer of particles 3 and emerges therefrom in the irradiation area 350. Such suction means 6 are then configured to aspirate the air in the casing 2 above the freeboard 35 of the layer of particles 3. In the present example, the suction means 6 comprise an element 61, for example in the form of a hood, arranged on the upper wall 21 of the casing 2, for collecting air from the free space 350.

[0086] Preferably, the suction means 6 is configured to avoid ejection or even mass ejection of fluidizing air and / or particles thereby being drawn through the opening 10 into the external environment.

[0087] Advantageously, the suction means 6, in synergy with a control means (not shown), preferably an additional control means (not shown) associated with the fluidisation means 4, provides a flow sensor which determines the air flow extracted from the device 1 to be equal to or higher than the fluidisation air flow which has penetrated the layer 3 of particles.

[0088] Advantageously, the device 1 provides for a heat exchange between the (heated) fluidizing air emerging from the bed of particles 3 at the freeboard 35 of the bed of particles and drawn in by the means 6, and the fluidizing air entering the bed of particles 3 by the fluidizing means 4. In other words, a heat regeneration obtained by the heat exchange means is provided. This is represented diagrammatically in the figure by a heat exchange component 512, a component 513 for dedusting the fluidizing air, a component 514 for drawing in the fluidizing air from the external environment and a component for drawing in air 515 into the fluidizing system belonging to the fluidizing means 4.

[0089] In one embodiment variant, the device 1 has a gentle chamber above the freeboard 35 of the layer 3 of particles. Such a gentle chamber is meant as an area of ​​low or zero velocity of the layer particles, and is defined in this example by an empty space 350.

[0090] Even a gentle chamber contributes to avoiding leakage or bulk leakage of air and / or particles through the opening 10.

[0091] An exemplary configuration of a plant such as the one discussed above, including a 350 ton bed of particles, can be implemented using one or more of the following dimensional parameters: -About 10,000m 2 of the reflective surface of a field heliostat. A minimum focal length of 60 m and a maximum focal length of 200 m, the focal length being defined as the distance between the center of the heliostat and the focus of the parallel solar beam striking it. -The inlet opening of the device will be placed at an altitude of approximately 40 m relative to the heliostat field on the ground. - the dimensional ratio between the total extension of the internal reflective surfaces of the device and the total extension of the surfaces of the inlet openings, approximately equal to 15-20;

[0092] The device of the present invention is modular, i.e., well suited for connection to one or more analog devices in series or parallel for heat exchange.

[0093] Furthermore, the types of apparatus according to the different configurations and embodiment variants described can be advantageously associated for greater production and / or operational flexibility of industrial plants.

[0094] In a further preferred configuration, a plant based on one or more of the devices of the invention can be advantageously associated with a photovoltaic system providing a daily generation of electrical energy. In such a configuration, the storage and transmission device can be managed in a regime of storing thermal energy of solar origin during sunny hours and in a regime of transmitting thermal energy from dusk onwards.

[0095] Moreover, in the same configuration, the plant can be associated with a plant for desalination or other systems for utilizing thermal energy of solar origin. In this case, the device can manage both the storage, night-time production and the modern daily transfer of electrical energy by allocating a mixed regime, for example the transfer of the associated thermal energy, to the continuous operation of the plant, for example the desalination operation.

[0096] The device of the present invention can be integrated with plants supplied by other renewable energy sources (e.g. solar power, wind, geothermal) or non-renewable energy sources to ensure continuity of energy production with the aim of reducing or eliminating the production of energy generated by non-renewable sources.

[0097] The invention further provides a method for the storage and exchange of thermal energy of solar origin, based on the features already described above for the device and plant of the invention.

[0098] The object of the present invention has been described above with reference to its preferred embodiments. There may be other embodiments belonging to the same inventive core, all of which are meant to be within the scope of protection of the claims reported below.

Claims

1. a containment casing (2) having an illumination opening (10) configured to allow the entry of incident solar radiation into an illumination area (350) defined in said containment casing (2), said illumination opening (10) being arranged in a side skirt (22) of said containment casing (2); a layer (3) of flowable particles received in said containment casing (2); a plurality of reflective surfaces (701, 702, 703) arranged in said illumination area (350) and each of said plurality of reflective surfaces configured to reflect the solar radiation penetrating through said illumination opening (10) directly onto an upper surface (35) of said layer of particles (3) or onto another reflective or re-emitting surface of said illumination area (350), The overall arrangement is such that incoming solar radiation strikes the upper surface (35) of the layer of particles (3) below the point of multiple reflections on the reflective surfaces (701, 702, 703), the particles of the layer of particles (3) have a higher absorbance than the reflective surface (701, 702, 703); A device for the storage and transmission of thermal energy of solar origin (1).

2. a heat exchange means (5) thermally connected to said layer of particles (3) and operable to receive thermal energy therefrom, the whole arrangement being such that said thermal energy is transferred from incoming solar radiation to the particles of said layer of particles (3) and simultaneously or subsequently from said particles to the heat exchange means (5), The heat exchange means comprises one or more of the following components: a thermoelectric element, a thermoelectronic element, a thermophotovoltaic element, a tube bundle (5) configured to intersect with the working fluid in use.

2. Apparatus (1) according to claim 1.

3. means for supplying the heated fluidizing gas emerging from said bed of particles (3) to a user, 3. Apparatus (1) according to claim 1 or 2.

4. said illumination opening (10) directly communicates said illumination area (350) of said containment casing (2) with the external environment, and in use, the closing or shielding means are removed; An apparatus (1) according to any one of claims 1 to 3.

5. The illumination opening (10) is arranged near the upper wall (21) of the containment casing. An apparatus (1) according to any one of claims 1 to 4.

6. the upper surface (35) of the layer of particles (3) is located below the lower edge (230) of the irradiation opening (10) even under fluidized conditions, An apparatus (1) according to any one of claims 1 to 5.

7. said reflecting surfaces (701, 702, 703) are advantageously configured to re-radiate in said illuminated area (350) the thermal energy absorbed by solar radiation according to a radiation cavity configuration, An apparatus (1) according to any one of claims 1 to 6.

8. The reflecting surfaces (701, 702, 703) and / or the re-emitting surfaces are mounted on inclined walls housed within the irradiation area (350) or are associated with walls (21, 22) defining the containment casing (2), and the sum of the radiation emitted by the re-emitting surfaces and the radiation reflected by the reflecting surfaces is absorbed by the layer of particles (3), An apparatus (1) according to any one of claims 1 to 7.

9. The reflective surfaces (701, 702, 703) have a reflectivity that belongs to one of the following: specular reflectivity, where the radiation reflection angle is equal to the incidence angle, diffuse reflectivity, where the reflection in all directions is independent of the radiation incidence surface, and glossy reflectivity, which has a hybrid behavior of specular reflectivity and diffuse reflectivity. An apparatus (1) according to any one of claims 1 to 8.

10. the containment casing (2) is made of a heat insulating material, except for the irradiation openings (10); An apparatus (1) according to any one of claims 1 to 9.

11. said containment casing (2) being made of a material resistant to high temperatures and with a system for heat recovery and / or heat loss, An apparatus (1) according to any one of claims 1 to 10.

12. a fluidizing means (4) configured to introduce a fluidizing gas into said bed (3) of flowable solid particles, An apparatus (1) according to any one of claims 1 to 11.

13. means for selectively varying the flow rate and / or velocity of the fluidizing gas; An apparatus (1) according to any one of claims 1 to 12.

14. a suction means (6) having in particular a substantially hood-like configuration (61) and configured to suction a fluidizing gas above the upper surface (35) of the bed of particles (3), An apparatus (1) according to any one of claims 1 to 13.

15. a heat exchange means (512) between the fluidizing gas leaving the bed of particles (3) and the fluidizing gas entering the bed of particles (3), 15. Apparatus (1) according to claim 12 or 14.

16. a heating means thermally connected to the layer of particles (3), the heating means being configured to transfer thermal energy to the particles; An apparatus (1) according to any one of the preceding claims.

17. a support structure (800) configured to maintain the containment casing (2) at an altitude above ground level; An apparatus (1) according to any one of the preceding claims.

18. A plant for the production of electrical and / or thermal energy, comprising: - one or more devices (1) according to any one of claims 1 to 17, located at high altitude; - collection means (500) for collecting solar radiation, located on the ground and comprising a number of heliostats (501), The arrangement comprises a means (500) whereby solar radiation is collected by said collecting means (500) and concentrated on the illumination opening (10) of one or more devices (1), said collecting means (500) or a subgroup thereof concentrating the solar radiation on a common focal point (F) arranged at or near said illumination opening (10) of the device (1), said collecting means (500) defining a radiation configuration for focusing solar radiation onto said one or more devices (1) from below; plant.

19. 19. A method for producing electrical and / or thermal energy starting from the thermal energy of solar radiation using a device or plant according to any one of claims 1 to 18, comprising the steps of: a first stage for the concentration of solar radiation at an irradiation opening (10) of a receiver device (1) comprising a layer (3) of particles for the storage of thermal energy, of the type having flowable particles, and providing multiple reflections of solar radiation on said layer of particles by a plurality of reflective surfaces (701-703) arranged below said illumination opening (10), method.

20. a second stage of transferring thermal energy by the particles of the layer of particles (3), said second stage being selectively activatable simultaneously with the first stage or after the first stage, 20. The method of claim 19.

21. using a heated fluidizing gas exiting the bed of particles (3), 21. The method of claim 19 or 20.

22. a step of fluidization of the particles of the layer of particles (3), which is activated under selected operating conditions, 22. The method according to any one of claims 19 to 21.

23. providing selective adjustment of the flow rate and / or flow rate of the fluidizing gas; 23. The method according to any one of claims 19 to 22.

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