Apparatus for the conversion of electromagnetic radiation into electric current and heat

Abstract

Apparatus (1) for converting electromagnetic radiation into electric current and heat comprising a conversion module (2) and a concentration module (3) configured to concentrate electromagnetic radiation towards said conversion module (2). The conversion module (2) comprises a waveguide (4) configured to transmit electromagnetic radiation in a predefined wavelength range, a photoelectric layer (5) configured to absorb the electromagnetic radiation (E) transmitted by the waveguide (4), generating a first direct electric current (E1 ), a thermoelectric layer (6) configured to absorb a heat emitted by the photoelectric layer (5), generating a second direct electric current (E2), a heat exchanger (7) configured to transfer a residual heat emitted by the thermoelectric layer (6) to an external fluid (8), and an inverter (9) configured to transfer the first and the second direct electric currents (E1, E2) to an external electricity grid.

Description

[0001] APPARATUS FOR THE CONVERSION OF ELECTROMAGNETIC RADIATION INTO ELECTRIC CURRENT AND HEAT

[0002] FIELD OF APPLICATION

[0003] The present invention relates to an apparatus for converting electromagnetic radiation into electric current and heat.

[0004] In particular, the present invention relates to an apparatus for converting electromagnetic radiation into electric current and heat based on concentration systems, for the building and energy sector, for use in both domestic and industrial contexts.

[0005] In even more detail, the invention relates to an apparatus specially designed to convert electromagnetic radiation into electrical energy and heat for domestic use, industrial use and any other situation where energy supply is needed.

[0006] PRIOR ART

[0007] Concentration plants are known; however, these are limited to concentrating sunlight so as to obtain concentrated heat focused in a point and then transfer this energy to an energy carrier, i.e., water or molten salts, which in turn operate turbines connected to electric generators through thermal cycles.

[0008] However, the Applicant has noted that the resulting overall efficiency through these energy steps is poor. In addition, the system is often complex, with moving mechanical parts which require significant scheduled maintenance and management costs.

[0009] In other known systems, heat is harnessed to operate thermoelectric devices placed in the focal point with poor energy efficiency yields which hardly exceed 10%.

[0010] The Applicant has also noted that the systems of the prior art are often bulky and noisy, making them difficult to install and incorporate into building and industrial systems. In this context, the technical task underlying the present invention is to propose an apparatus for converting electromagnetic radiation into electric current and heat which overcomes one or more of the drawbacks of the prior art mentioned above.

[0011] In particular, it is the aim of the present invention to provide an apparatus for the conversion of electromagnetic radiation into electric current and heat which is structurally simple and has high energy performance.

[0012] A further aim of the present invention is to propose an apparatus for converting electromagnetic radiation into electric current and heat which is capable of exploiting solar electromagnetic radiation to produce and transfer electric current and heat efficiently.

[0013] Unlike the existing systems, the apparatus proposed by the present invention is able to offer a quantum conversion efficiency approaching 100% (up to 60% for the electrical part and up to 40% for the thermal part), offering a structurally simple system lacking moving mechanical parts for thermoelectric conversion.

[0014] SUMMARY OF THE INVENTION

[0015] The defined technical task and the specified aims are substantially achieved by an apparatus for converting electromagnetic radiation into electric current and heat, comprising the technical characteristics set forth in one or more of the appended claims.

[0016] In particular, the present invention provides an apparatus for converting electromagnetic radiation into electric current and heat comprising a conversion module and a concentration module configured to concentrate electromagnetic radiation towards said conversion module.

[0017] Advantageously, therefore, the concentration module allows electromagnetic radiation to be received, transferred and concentrated on a specific surface of the conversion module.

[0018] In particular, the conversion module comprises: a waveguide, a photoelectric layer, a thermoelectric layer and a heat exchanger. The waveguide is made so as to allow to convey / transmit only the electromagnetic radiation having a wavelength within a predefined range of values.

[0019] In particular, the waveguide is configured to transmit electromagnetic radiation having a wavelength of between 100 nm and 1 cm.

[0020] Structurally, the waveguide has an outer face defining an outer surface of the conversion module exposed in use to an external environment and adapted to receive the concentrated electromagnetic radiation from the concentration module.

[0021] The photoelectric layer is made of semiconductor material and is configured to absorb the electromagnetic radiation transmitted through the waveguide and simultaneously generate a first direct electric current.

[0022] In other words, advantageously, the photoelectric layer is able to absorb the electromagnetic radiation, producing an electric current through the effect by which the energy of the electromagnetic radiation is transferred to the electron, generating an electric current (called the photoelectric effect). The thermoelectric layer is made of semiconductor material and is configured to at least partially absorb a heat emitted by the photoelectric layer as a result of the absorption of the electromagnetic radiation and simultaneously generate a second, direct electric current.

[0023] In other words, the thermoelectric layer is advantageously able to absorb and transfer heat, producing direct electric current through the Seebeck effect.

[0024] The heat exchanger is configured to transfer a residual heat emitted by the thermoelectric layer to an external fluid, such as water or gas.

[0025] Advantageously, the apparatus further comprises an inverter connected, or adapted to be connected, to the conversion module and to an external electricity grid to transfer the first direct electric current and the second direct electric current to said external electricity grid.

[0026] Thanks to the present apparatus, therefore, first the electromagnetic radiation specifically selected within a range of values of interest is converted and then the heat is converted, proceeding by steps / stages in a unidirectional system which goes from the waveguide, to the photoelectric layer, to the thermoelectric layer and finally to the heat exchanger. In other words, only the portion of electromagnetic radiation contained within a useful range is conveyed to the photoelectric layer so as to avoid an excessive overheating thereof, which would instead be present if the latter were also reached by electromagnetic radiation in ranges not adapted to efficiently trigger the photoelectric effect.

[0027] Moreover, advantageously, the conversion efficiency of the photoelectric layer is very high, as only electromagnetic radiation in a well-defined and appropriately selected range by means of the waveguide is concentrated on small surfaces by the conversion module (effectively reducing the need to provide a bulky and expensive conversion module); in particular in the case of composite materials, whether silicon-, gallium- or germanium- based, the quantum efficiency can be well in excess of 40%.

[0028] The excess energy present which is not converted into the first direct electric current at this stage (that of the photoelectric layer) or otherwise resulting from the normal operation of the device, through the conversion module proposed by the present invention, is transferred to the heat exchanger but passing through the thermoelectric layer, which converts a further 10% thereof, producing the second direct electric current.

[0029] This cascade system of the conversion module proposed by the present invention thus maximises conversion efficiency while avoiding overheating phenomena and thus the possible deterioration of the semiconductor material of the photoelectric layer.

[0030] The remaining thermal component of the energy transferred from the thermoelectric layer, which is now of low energy value, arrives at the heat exchanger, which can be transferred to a fluid or a gas. A possible application example is heating water for domestic heating purposes.

[0031] Lastly advantageously, the presence of the inverter allows the apparatus to output grid current. Advantageously, thanks to the apparatus for converting electromagnetic radiation into electric current and heat based on concentration systems proposed by the present invention, it is therefore possible to produce electric current and heat with high efficiencies without having thermal cycles with moving mechanical parts therein, and with a very small footprint.

[0032] The dependent claims herein incorporated for reference, correspond to different embodiments of the invention.

[0033] Further characteristics and advantages of the present invention will appear more clearly from the indicative, and therefore non-limiting, description of a preferred but not exclusive embodiment of an apparatus for converting electromagnetic radiation into electric current and heat, as illustrated in the accompanying drawings.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 depicts an operating schematic of the apparatus for converting electromagnetic radiation into electric current and heat which is the subject matter of the present invention.

[0036] Figure 2 depicts a first embodiment of the apparatus of Figure 1 .

[0037] Figure 3 depicts a second embodiment of the apparatus of Figure 1 .

[0038] Figure 4 depicts a third embodiment of the apparatus of Figure 1 .

[0039] Figure 5 depicts a fourth embodiment of the apparatus of Figure 1 .

[0040] Figure 6 graphically illustrates the operating efficiency of one of the components of the apparatus.

[0041] DETAILED DESCRIPTION

[0042] With reference to the attached figures, 1 denotes overall an apparatus for converting electromagnetic radiation into electric current and heat, henceforth and simply apparatus 1 . Apparatus 1 comprises a conversion module 2 and a concentration module 3 configured to concentrate electromagnetic radiation E towards conversion module 2.

[0043] With reference to the embodiment of apparatus 1 illustrated in Figure 2, preferably the concentration module 3 comprises a reflecting element 3', such as a paraboloid, configured to reflect electromagnetic radiation E and concentrate it on an outer surface 2a of conversion module 3 (as indicated by the arrows E33').

[0044] In other words, electromagnetic radiation E is reflected from an inner surface 3'a of reflecting element 3' to be concentrated on outer surface 2a of conversion module 2.

[0045] With reference to the embodiment of apparatus 1 illustrated in Figure 3, preferably concentration module 3 comprises a deflecting element 3", such as a lens or a sequence of lenses, configured to concentrate electromagnetic radiation E on outer surface 2a of conversion module 2 (as indicated by the arrows E3").

[0046] In other words, the electromagnetic radiation E hitting an outer surface 3"a of deflecting element 3" passing through deflecting element 3" itself is concentrated towards outer surface 2a of conversion module 2.

[0047] Concentration module 3 thus allows electromagnetic radiation E hitting its surface to be focused on a specific surface (outer surface 2a) as concentrated electromagnetic radiation Es’.Es" adapted to be converted to exploit it effectively and efficiently.

[0048] Preferably concentration module 3 is made of silicon oxide, viz., glass, or methacrylate, such as plexiglass.

[0049] Advantageously, these materials are able to concentrate electromagnetic radiation in the spectrum ranging from infrared to ultraviolet with high efficiency.

[0050] Conversion module 2 comprises a waveguide 4, a photoelectric layer 5, a thermoelectric layer 6 and a heat exchanger 7. Waveguide 4 (illustrated in Figure 1 with a plate-like structure solely for the sake of simplicity) is made of material which is only transparent to electromagnetic radiation in a specific and predefined wavelength range.

[0051] In other words, the waveguide is configured to only transmit / convey the electromagnetic radiation within a specific range of wavelength values.

[0052] Viz., waveguide 4 is designed so as to propagate the received electromagnetic signal, filtering out most of the frequencies which cannot be fully converted into electrical power by the material with which photoelectric layer 5, to which the radiation is conveyed, is composed.

[0053] The filtering is thus adapted to the absorption peaks of the material of photoelectric layer 5 and thereby most of the electromagnetic energy in input is converted into electricity.

[0054] Therefore, waveguide 4 operationally defines a protection of the photoelectric layer 5 thanks to a filtering of the electromagnetic radiation which cannot be usefully converted into electric current by the latter.

[0055] Waveguide 4 thus overall defines a filtering layer of apparatus 1 .

[0056] Preferably, the filtering range of the waveguide is between 100 nm and 1 cm, viz., only electromagnetic radiation having a wavelength in the indicated range is conveyed / transmitted by waveguide 4.

[0057] Such a waveguide 4 has an outer face 4' opposite an inner face facing photoelectric layer 5.

[0058] Such external face 4' defines outer surface 2a of conversion module 2, viz., the surface exposed in use to an external environment and adapted to receive the electromagnetic radiation Es’.Es" concentrated by concentration module 3.

[0059] In the embodiments illustrated in Figures 4 and 5, the waveguide comprises an optical fibre F, preferably a total internal reflection fibre, which can for example have a length in the order of a metre or tens of metres.

[0060] Advantageously, waveguide 4, in particular its outer face 4', can comprise a protective layer made of silicon oxide or methacrylate. Advantageously, these materials are able to offer high transparency to the electromagnetic radiation, allowing an optimal transfer efficiency of the radiation of interest.

[0061] Preferably, protective layer 4 has an average thickness of between 1 pm and 10 mm, even more preferably of 1 mm.

[0062] Photoelectric layer 5 is made of semiconductor material and is configured to absorb electromagnetic radiation E4 transmitted through waveguide 4 and simultaneously generate a first direct electric current E1 .

[0063] Preferably photoelectric layer 5 made of semiconductor material is made with materials comprising graphene, silicon, germanium, or gallium.

[0064] In particular, graphene is able to offer excellent properties as a storage and preservation of electrical charge, being an excellent electrical conductor even on thicknesses of a few atomic layers.

[0065] Preferably, photoelectric layer 5 has an average thickness of between 100 pm and 1 mm, even more preferably of 200 pm.

[0066] By way of example, in accordance with a possible embodiment of apparatus 1 presented herein, photoelectric layer 5 can comprise three sub-layers: a first 2.5um thick InGaP layer, a second 2.5um thick InGaAs layer and a third 150um thick germanium layer. These 3 layers generate two quantum tunnel effect junctions, generating an excellent conversion efficiency (over 40%) of the electromagnetic radiation in the visible and infrared light range, in particular of between 400 nm and 2000 nm.

[0067] A particular example of the trend of the conversion capacity of a possible photoelectric layer is illustrated in Figure 6, where the conversion quantum efficiency (EQE) as a function of the wavelength of radiation hitting the photoelectric layer 5 is illustrated.

[0068] Such figure 6 thus specifically illustrates the quantum conversion efficiency of photoelectric layer 5 in two measurements, in which it can be seen that there is a peak present between 300 nm and 700 nm with essentially zero efficiencies for wavelengths outside this range, which can thus be appropriately filtered and thus eliminated upstream thanks to the action of waveguide 4, thus avoiding the unwanted transmission of radiation which that would only contribute to a potentially harmful heating of the apparatus 1.

[0069] In this specific context, the above-mentioned range defines the predefined operating range of waveguide 4, viz., the waveguide is configured to only transfer / convey the electromagnetic radiation in the range of 300 nm to 700 nm.

[0070] However, it should be pointed out that such conversion can in any case generate an increase in the temperature of conversion module 2, which, although limited by the implementation of waveguide 4, can be advantageously exploited to further increase the generation of electric current.

[0071] For this purpose, thermoelectric layer 6 is made of semiconductor material and is configured to at least partially absorb a heat Es emitted by photoelectric layer 5 as a result of the absorption of electromagnetic radiation and simultaneously generate a second direct electric current E2. Preferably, thermoelectric layer 6 is made of silicon.

[0072] Preferably, thermoelectric layer 6 has an average thickness of between 1 mm and 10 mm, even more preferably of 3 mm.

[0073] The heat exchanger 7 is configured to transfer a residual heat Ee emitted by thermoelectric layer 6 to an external fluid 8, e.g., water or gas.

[0074] Preferably, heat exchanger 7 is made of copper, aluminium or an ironcarbon alloy.

[0075] In particular, heat exchanger 7 can also be a simple radiator.

[0076] The remaining thermal component of the energy transferred from thermoelectric layer 5, which is now of low energy value, thus arrives at heat exchanger 7 and can be transferred to a fluid or a gas. A possible application example is heating water for domestic heating purposes. Finally, advantageously, apparatus 1 further comprises an inverter 9 connected, or adapted to be connected, to conversion module 2 and an external electricity grid, not illustrated in the attached figures, to transfer first direct electric current E1 (generated by photoelectric layer 5) and second direct electric current E2 (generated by thermoelectric layer 6) to the external electricity grid.

[0077] The operating principle of the apparatus is schematically shown in Figure 1. Apparatus 1 receives an energy E in input, viz., electromagnetic radiation. This energy E is then concentrated by concentration module 3 with an efficiency r|3 and transferred to waveguide 4, which in turn transmits it to photoelectric layer 5 with an efficiency r|4.

[0078] The resulting conversion into electrical energy E1 is thus given by:

[0079] E1 = E r|3 r|4 rjs where qs is the conversion efficiency of photoelectric layer 5.

[0080] Consequently, E2 is given the resulting unconverted energy transferred to thermoelectric layer 6 multiplied by the conversion efficiency of thermoelectric layer qe:

[0081] E2 = r|6 r|3 r|4 E (1 -qs)

[0082] The total direct electrical energy Etot is thus given by:

[0083] Etot =E1 +E2 = E qs r|4 (r|5 +r|6 (1 -qs))

[0084] The overall conversion efficiency into electrical energy by means of apparatus 1 can be estimated at at least 50% of the electromagnetic radiation received through waveguide 4.

[0085] The resulting energy yielded in the form of heat is thus given by:

[0086] Es = r|7 (1 -qe) qs r|4 E (1 -qs) where q? is the transfer efficiency of heat exchanger 7 of the unconverted energy from thermoelectric layer 6 to the external fluid. A possible example embodiment could therefore be a heat exchanger which transfers energy to a fluid or gas.

[0087] Preferably, conversion module 2 and concentration module 3 are arranged at an average distance of between 1 cm and 100 cm, even more preferably of 20 cm.

[0088] In other words, the two modules are not in direct contact with each other, but are spaced as according to the constructional / design requirements of apparatus 1 and the electromagnetic radiation concentration property of concentration module 3, viz., reflecting or deflecting capacities.

[0089] According to a possible aspect of the present invention, preferably conversion module 2 is made so that photoelectric layer 5 and / or thermoelectric layer 6 are made in sheet form or in tubular form.

[0090] Advantageously, if such layers are made in tubular form, conversion module 2 is particularly compact and can also be used to make solar collectors in which water flows or which are in any case more efficient, as the entire surface of photoelectric layer 5 is optimally facing the waveguide exit to receive the radiation conveyed by the latter.

[0091] In the case of sheet form, the dual layer has the shape of a flat panel, so that the thickness, measured perpendicularly with respect to outer surface 4', is variable depending on the design requirements, but in any case has a much lower value with respect to the other two dimensions.

[0092] However, in accordance with a possible alternative embodiment not illustrated in the attached figures, dual layer 5, 6 could be made with curved or irregular forms, depending on the specific application.

[0093] The present invention achieves the proposed aims, overcoming the drawbacks complained of in the prior art and providing the user with an apparatus for converting electromagnetic radiation into electric current and heat which is structurally simple, efficient and characterised by high conversion performance, and highly versatile in use.

Claims

CLAIMS1. Apparatus (1 ) for converting electromagnetic radiation into electric current and heat comprising a conversion module (2) and a concentration module (3) configured to concentrate electromagnetic radiation (E) towards said conversion module (2); wherein said conversion module (2) comprises:- a waveguide (4) configured to transmit electromagnetic radiation in a predefined range of wavelengths and having an outer face (4’) defining an outer surface (2a) of said conversion module (2) exposed in use to an external environment and adapted to receive said electromagnetic radiation (E) concentrated by the concentration module,- a photoelectric layer (5) made of a semiconductor material configured to absorb the electromagnetic radiation (E) in said predefined range of wavelengths transmitted through said waveguide (4) and simultaneously generate a first direct electric current (E1 ),- a thermoelectric layer (6) made of a semiconductor material configured to at least partially absorb a heat emitted by said photoelectric layer (5) as a result of the absorption of said electromagnetic radiation (E) and simultaneously generate a second direct electric current (E2),- a heat exchanger (7) configured to transfer a residual heat emitted by the thermoelectric layer (6) to an external fluid (8); said apparatus (1 ) further comprising an inverter (9) connected, or adapted to be connected, to said conversion module (2) and to an external electricity grid to transfer the first direct electric current (E1 ) and the second direct electric current (E2) to said external electricity grid.

2. Apparatus (1 ) according to claim 1 , wherein said concentration module (3) comprises a reflecting element (3'), such as a paraboloid, configured toreflect the electromagnetic radiation (E) and concentrate it on said outer surface (2a) of the conversion module (2), or comprises a deflecting element (3”), such as a lens or a sequence of lenses, configured to concentrate the electromagnetic radiation (E) on said outer surface (2a) of the conversion module (2).

3. Apparatus (1 ) according to claim 1 or 2, wherein said concentration module (3) is made of silicon oxide or methacrylate, such as plexiglass.

4. Apparatus (1 ) according to any one of the preceding claims, wherein said conversion module (2) and said concentration module (3) are arranged at an average distance of between 1 cm and 100 cm, preferably of 20 cm.

5. Apparatus (1 ) according to any one of the preceding claims, wherein said heat exchanger (7) is made of copper, aluminium or an iron-carbon alloy.

6. Apparatus (1 ) according to any one of the preceding claims, wherein said waveguide comprises, at the outer layer (4'), a protective layer made of silicon oxide or methacrylate, preferably said protective layer has an average thickness of between 1 pm and 10 mm.

7. Apparatus (1 ) according to any one of the preceding claims, wherein said photoelectric layer (5) of semiconductor material is made of graphene, silicon, germanium, or gallium.

8. Apparatus (1 ) according to any one of the preceding claims, wherein said thermoelectric layer (6) made of a semiconductor material is made of silicon.

9. Apparatus (1 ) according to any one of the preceding claims, wherein- said photoelectric layer (5) has an average thickness of between 100 pm and 1 mm, preferably 200 pm; - said thermoelectric layer (4) has an average thickness of between 1 mm and 10 mm, preferably of 3 mm.

10. Apparatus (1 ) according to any one of the preceding claims, wherein at least the photoelectric layer (5) is made in sheet form.

11. Apparatus (1 ) according to any one of the preceding claims 1 to 9, wherein at least the photoelectric layer (5) is made in tubular form.

12. Apparatus (1 ) according to any one of the preceding claims, wherein the waveguide (4) comprises an optical fibre (F), preferably a total internal reflection optical fibre (F), having a first end defining the outer face (4') and a second end facing the photoelectric layer (5) so as to only convey the electromagnetic radiation in the predefined wavelength range from the outer surface (2a) to the photoelectric layer (5).

Images