Photoacousto-electrical conversion device and associated electrical energy production process

Abstract

PHOTO-ACOUSTO-ELECTRICAL CONVERSION DEVICE AND ASSOCIATED ELECTRICAL ENERGY PRODUCTION METHOD Photo-acousto-electrical conversion device (100, 200, 300) comprising at least one collector (10, 20, 30) of electromagnetic radiation (900) for receiving and maximizing electromagnetic energy Eray of said radiation, at least one photoacoustic cell (12, 12a, 12b, 12c, 22, 32) operationally coupled to the collector (10, 20, 30), said photoacoustic cell being configured to generate acoustic energy Eac by photoacoustic effect from the electromagnetic energy Eray wholly or partly contained in the electromagnetic radiation (900), said device further comprising at least one electroacoustic transducer (13, 23, 33) operationally coupled to the photoacoustic cell (12, 12a, 12b, 12c, 22, 32) to convert acoustic energy Eac into electrical energy Eelec, and an electrical energy storage system (14, 24, 34),said device converting electromagnetic energy Eray into electrical energy Eelec and storing the electrical energy Eelec in the electrical energy storage system (14, 24, 34). Figure from the abstract: Figure 1,

Description

Title of the invention: Photoacousto-electric conversion device and associated electrical energy production method technical field

[0001] The present invention belongs to the technical field of electrical power production systems.

[0002] The invention relates more particularly to a photo-acousto-electric conversion device and to a method of producing electrical energy by means of said device.

[0003] The invention finds a direct application in the energy sector, in particular for the production of electricity from solar radiation, in an isolated manner for portable equipment and for low power. State of the art

[0004] The photoacoustic effect is a well-known phenomenon, primarily used in spectroscopy for the detection and measurement of gas concentrations. This process involves the use of a laser that emits photons at a specific wavelength to subsequently generate an acoustic wave, which intensifies with increasing concentration of the analyzed gas. By measuring the acoustic pressure in a frequency band of interest, it is possible to determine the specific concentration of the target gas within a gas mixture.

[0005] Most of the light sources used are pulsed or frequency-modulated lasers, which offer high selectivity and high sensitivity, necessary for gas discrimination and for environmental or medical monitoring applications.

[0006] These lasers require a power supply for their operation. These power supplies are of the high electrical power type and are not compatible with applications in the field of energy production.

[0007] On the other hand, devices are also known whose purpose is to convert acoustic energy into electrical energy.

[0008] The document YUAN, M. et al., Recent developments of acoustic energy harvesting: A review, Micromachines, 2019, Vol. 10(1), 48 describes various techniques and devices for converting acoustic energy, some of which can harvest a few milliwatts of electrical energy from ambient noise with sound pressure levels ranging from 100 to 120 dB SPL.

[0009] This conversion of acoustic energy into electrical energy is, for example, achieved through piezoelectric materials. This technology has found applications in numerous disciplines, for example, energy harvesting from vibrations in industrial machines or transport systems, or even in the development of autonomous electronic devices.

[0010] The conversion of acoustic energy, produced from the photoacoustic effect, into electrical energy is a solution that could complement existing technologies, especially if the source is a renewable energy source.

[0011] On the other hand, there is currently no architecture of such devices that allows for obtaining a positive energy balance. Presentation of the invention

[0012] The present invention aims to overcome all or part of the disadvantages presented above.

[0013] To this end, the present invention relates firstly to a photoacousto-electrical conversion device comprising at least one electromagnetic radiation collector to receive and maximize electromagnetic energy Eray of said radiation, at least one photoacoustic cell operationally coupled to the collector, said photoacoustic cell being configured to generate acoustic energy Eac by photoacoustic effect from the electromagnetic energy Eray wholly or partly contained in the electromagnetic radiation, said device further comprising at least one electroacoustic transducer operationally coupled to the photoacoustic cell to convert the acoustic energy Eac into electrical energy Eeiec, and an electrical energy storage system.The photoacousto-electrical conversion device is remarkable in that it converts electromagnetic energy Eray into electrical energy Eeiec and stores the electrical energy Eeiec in the electrical energy storage system.

[0014] According to a particular feature, the device further comprises an optical chopper, operationally coupled between the collector and the photoacoustic cell.

[0015] According to a particular feature, the optical chopper is an electromechanical chopper or an electro-optical chopper requiring that it be powered by electrical power from an energy source.

[0016] According to another particular characteristic, the optical chopper is an opto-mechanical chopper that does not require being supplied by electrical power.

[0017] Advantageously, the collector comprises a plurality of lenses or reflective internal walls.

[0018] Advantageously, the collector is fixed.

[0019] Advantageously, the collector is mobile in order to follow the maximum of the electromagnetic radiation and thus maximize the electromagnetic energy transmitted to the device.

[0020] According to a particular characteristic, the electroacoustic transducer is a piezoelectric element.

[0021] Advantageously, the photoacoustic cell pivots around an axis of rotation, the rotation frequency of said cell being defined in such a way that it then maximizes the generation of an acoustic wave by means of the photoacoustic effect.

[0022] Advantageously, the electromagnetic energy Eray comes, one at a time or in combination, from solar radiation, from heat given off by a human body, from a light bulb or from a heating system.

[0023] The present invention also relates to a photo-acousto-electric conversion method operated by a photo-acousto-electric conversion device according to the invention, said method being remarkable in that it comprises the following steps: - of collecting electromagnetic energy Eray of electromagnetic radiation by means of a collector of said device; - the generation of an acoustic wave from electromagnetic radiation by means of at least one photoacoustic cell of said device; and - conversion of acoustic energy Eac into electrical energy Eeiec, by means of at least one electroacoustic transducer of said device.

[0024] According to a particular feature of the process, said process further comprises, between the step of collecting electromagnetic energy Eray and the step of generating an acoustic wave, a step of modulating the electromagnetic energy Eray.

[0025] The fundamental concepts of the invention having been set forth above in their most elementary form, other details and features will become clearer upon reading the following description and with reference to the accompanying drawings. Presentation of the drawings

[0026] The figures are given for illustrative purposes only to facilitate a better understanding of the invention without limiting its scope. The various elements may be represented schematically and are not necessarily to the same scale. Throughout the figures, identical or equivalent elements are identified by the same numerical reference.

[0027] It is thus illustrated in:

[0028] [Fig.1]: a diagram of a photo-acousto-electric conversion device, according to a first embodiment of the invention;

[0029] [Fig.2A]: a diagram of a photoacoustic cell of the conversion device, according to an embodiment of the invention;

[0030] [Fig.2B]: a diagram of a photoacoustic cell of the conversion device, according to another embodiment of the invention;

[0031] [Fig.2C]: a diagram of a photoacoustic cell of the conversion device, according to another embodiment of the invention;

[0032] [Fig.3]: a diagram of a photo-acousto-electric conversion device, according to a second embodiment of the invention;

[0033] [Fig.4]: a diagram of a photo-acousto-electric conversion device, according to a third embodiment of the invention; and

[0034] [Fig.5]: a diagram of a method for producing electrical energy by means of a photo-acousto-electrical conversion device, according to an embodiment of the invention. Detailed description of implementation methods

[0035] It should be noted that certain technical elements well known to those skilled in the art are described here to avoid any insufficiency or ambiguity in the understanding of the present invention.

[0036] In the embodiment described below, reference is made to a photoacousto-electrical conversion device and an associated electrical energy production method.

[0037] Figure 1 shows a diagram of a photoacousto-electric conversion device 100 according to a first embodiment of the invention. The photoacousto-electric conversion device 100 mainly comprises at least one collector 10, at least one optical chopper 11, at least one photoacoustic cell 12, at least one electroacoustic transducer 13 and an electrical energy storage system 14.

[0038] The collector 10 collects energy Eray from electromagnetic radiation 900. In a particular embodiment, the electromagnetic radiation 900 originates from sources such as solar radiation 91, heat emitted by a human body 92, a light bulb 93, or a heating system 94. Thus, the photoacousto-electrical conversion device 100 is capable of adapting to a large number of electromagnetic radiation sources 900, depending on the intended applications. By way of example, but not limited to, and for devices 100 with a size on the order of a centimeter, applications for powering embedded electronic equipment, connected objects, and / or equipment requiring power supplies on the order of 1 W are particularly targeted. For devices 100 with a larger volume, it is also envisaged to produce electrical power exceeding 10 W.

[0039] In a particular embodiment, the collector 10 comprises converging lenses and / or a plurality of reflective walls in order to concentrate the incoming electromagnetic energy Eray.

[0040] In a particular embodiment, the collector 10 is movable and orients itself in the direction in which the electromagnetic radiation 900 exhibits a maximum of electromagnetic energy Eray. The mobility of the collector 10 is ensured by means of a motor (not shown here), the orientation of the collector 10, as a function of the maximum electromagnetic energy Eray, being determined by means of a tracker measuring the emission of said energy at several angles.

[0041] In the particular embodiment shown in [Fig.1], once the electromagnetic energy Eray is collected by the collector 10, said energy is transmitted to the optical chopper 11 to modulate said energy before it is transmitted to the photoacoustic cell 12 and said cell generates an acoustic wave.

[0042] The optical chopper 11 is in a particular embodiment of the invention an electro-mechanical or electro-optical type chopper, and in this case requires to be powered by an external energy source 15 to operate, which is, in the embodiment connected to the electrical energy storage system 14.

[0043] One of the main objectives of the invention being that the device 100 has a positive energy efficiency, it is therefore necessary that the energy consumed by the optical chopper 11 be less than the electrical energy that will be produced by said device. Furthermore, it is also necessary to initiate energy production by photoacoustic effect in the photoacoustic cell 12. In this case, the external energy source 15 allows the electrical energy storage system 14 to be charged.

[0044] In a particular embodiment of the invention, and once the charge of the electrical energy storage system 14 has been initiated, said charge is withdrawn when the device 100 is in an energy self-sufficient operating regime.

[0045] In another embodiment of the invention, the external energy source 15 meets all or part of the energy requirements of the optical chopper 11.

[0046] Preferably, the external energy source 15 comes from a renewable energy source such as solar energy and by means of at least one solar panel (not shown here).

[0047] The main function of the optical chopper 11 is to modulate the incoming electromagnetic energy Eray. Advantageously, the optical chopper 11 can also be used to cool the environment surrounding the device 100 by creating an airflow. In this case, the electromechanical optical chopper 11 is a fan comprising a plurality of blades through which the electromagnetic radiation Eray passes.

[0048] In another embodiment of the invention, the optical chopper 11 is a mechanical or opto-mechanical type chopper. In this embodiment, the optical chopper 11 periodically presents an absorbing or reflective material at the output of the collector 10 in order to modulate the electromagnetic energy Eray.

[0049] Advantageously, it is not necessary to supply electricity to the optical chopper 11 in this embodiment, the periodic rotation of said chopper being able to be achieved for example by means of a driving force from wind energy.

[0050] The photoacoustic cell 12 will, from the modulated electromagnetic energy Eray and by means of the photoacoustic effect, then generate an acoustic wave having an acoustic energy Eac.

[0051] The photoacoustic effect present in the photoacoustic cell 12 can be produced by means of different methods

[0052] In one embodiment, the photoacoustic effect is obtained in a volume of gas by absorption of the electromagnetic energy Eray modulated by molecules of said gas. The gas contained in the photoacoustic cell may be a gaseous mixture such as ambient air, or any other type of gas, at atmospheric pressure or higher, and at a given temperature and humidity, and which presents conditions conducive to the implementation of the photoacoustic effect.

[0053] In another embodiment of the invention, the photoacoustic effect occurs in a liquid medium such as water, compounds diluted or not in water, such as dyes, or solvents.

[0054] In another embodiment, the photoacoustic effect also occurs on the surface of at least one internal wall of the photoacoustic cell 12, the surface of said wall being covered wholly or partly by a material such as metal or plastic, said materials being wholly or partly covered by a fiber or fabric coating, said surface being able to be painted with dyes in an alternative embodiment. Thus, and in addition to the photoacoustic effect obtained within the volume of the photoacoustic cell, the acoustic energy Eac produced by said effect is maximized.

[0055] Only a part of the electromagnetic energy Eray is converted into acoustic energy Eac in the photoacoustic cell 12. Thus, and in a particular embodiment of the invention shown in [Fig.3], the modulated electromagnetic energy Eray which is not converted in the photoacoustic cell 12 can then be partially converted in other photoacoustic cells.

[0056] In a particular embodiment, the photoacoustic cell 12 comprises a resonant volume, shown in Figures 2A-2C. In this embodiment, the photoacoustic cell 12 generates an acoustic wave whose frequency is equal to a natural frequency of the resonating volume.

[0057] Preferably, the resonating volume is cylindrical in shape, but may be parallelepiped-shaped or spherical in other embodiments, in particular to facilitate the integration of said volume and / or to maximize a quality factor of said volume (by minimizing, by the shape of the resonating volume, the energy dissipated within said volume).

[0058] Preferably, the electroacoustic transducer 13 is positioned at an acoustic pressure antinode, that is, at the point where the acoustic pressure field is at its maximum. The invention is not dependent on a particular natural frequency: depending on the intended applications, the most suitable acoustic resonance mode will be chosen.

[0059] In another embodiment, the acoustic wave generated within the photoacoustic cell 12 is non-stationary. In other words, the natural resonance phenomenon is not exploited in this case, and the aim is to generate an acoustic wave whose frequency is less than 1 Hz, or whose frequency is close to one of the natural frequencies of the photoacoustic cell 12.

[0060] The acoustic energy Eac obtained by photoacoustic effect will then be converted into electrical energy Eeiec by means of the electroacoustic transducer 13.

[0061] In a particular embodiment, the electroacoustic transducer 13 is a piezoelectric element.

[0062] In a particular embodiment, a plurality of electroacoustic transducers 13 are arranged on a single photoacoustic cell 12, as may be the case when said cell has a length sufficient to accommodate all of said transducers.

[0063] The electrical energy Eeiec produced at the output of the electroacoustic transducer 13 is then stored in the electrical energy storage system 14, and then consumed when energy is required.

[0064] As mentioned previously, the device 100 is capable of producing preferably electrical powers between ImW and 1 W, without this representing a limitation to the present invention, a scaling of said device allowing to produce higher electrical powers.

[0065] Fig. 2A, Fig. 2B and Fig. 2C respectively represent diagrams of a photoacoustic cell 12a comprising a resonant volume 120a said to be closed, of a photoacoustic cell 12b comprising a resonant volume 120b said to be semi-open and of a photoacoustic cell 12c comprising a resonant volume 120c said to be open.

[0066] The closed resonant volume 120a comprises, at a first end, corresponding to the so-called incoming wall through which the electromagnetic energy Eray enters the photoacoustic cell 12a, a first material 121a, and at a second end, corresponding to the so-called outgoing wall through which the electromagnetic energy that is not converted into acoustic energy exits said cell, a second material 122a.

[0067] The semi-open resonant volume 120b comprises, at one end, corresponding to the so-called incoming wall through which the electromagnetic energy Eray enters the photoacoustic cell 12b, a material 121b.

[0068] Materials 121a, 122a and 121b exhibit a high acoustic reflection coefficient and a high electromagnetic transmission coefficient.

[0069] In the embodiments shown in Figures 2A to 2C, the portion of the modulated electromagnetic energy Eray that is not converted into acoustic energy Eac exits the photoacoustic cell.

[0070] In a particular embodiment of the invention, the modulated electromagnetic energy Eray enters the photoacoustic cell 12b via the open end of said cell. The internal walls of the photoacoustic cell 12b comprise either a material that absorbs the energy of electromagnetic waves or a material that reflects the energy of said waves. Thus, either the photoacoustic effect is maximized on the surface of the internal walls of the photoacoustic cell 12b due to the presence on said walls of a material that promotes said effect, or the photoacoustic effect is maximized in volume due to the multiple reflections of electromagnetic waves at the walls of said cell.

[0071] Figure 3 represents a diagram of a 200 photo-acousto-electric conversion device, according to a second embodiment of the invention.

[0072] The device 200 comprises a collector 20, an optical chopper 21, a plurality of photoacoustic cells 22, each of the photoacoustic cells being operationally coupled to an electroacoustic transducer 23, the electroacoustic transducer assembly 23 being electrically connected to an electrical energy storage system 24, and an external power source 25

[0073] Device 200 operates in a similar manner and has similar characteristics to that shown in [Fig. 1]. Device 200 differs, however, from that shown in the figure by the plurality of photoacoustic cells 22 connected in series that said device 200 comprises.

[0074] Figure 4 represents a diagram of a 300 photo-acousto-electric conversion device, according to a third embodiment of the invention.

[0075] The device 300 includes a collector 30, a photoacoustic cell 32, an electroacoustic transducer 33, an electrical energy storage system 34 and an external power source 35.

[0076] In this particular embodiment, the modulation of the electromagnetic energy Eray is achieved by means of a pivoting of an assembly comprising the photoacoustic cell 32 and the electroacoustic transducer 33 around an axis of rotation 329. Thus, the photoacoustic cell 32 is periodically presented to the electromagnetic radiation 900 which has been previously collected by the collector 30.

[0077] Fig. 5 represents a diagram of the main steps of a process 500 for the production of electrical energy operated by the device 100, 200 or 300, and according to an embodiment of the invention.

[0078] The 500 method for producing electrical energy mainly comprises: - A 510 step of collecting electromagnetic energy Eray; - A 520 step of electromagnetic energy modulation Eray; - A step 530 of generating an acoustic wave from radiation electromagnetic 900; - A step 540 of converting acoustic energy Eac into electrical energy Eeiec; and - A 550 stage of electrical energy storage Eeiec.

[0079] Step 510 of collecting electromagnetic energy Eray consists of collecting the maximum of electromagnetic energy Eray from electromagnetic radiation 900, by concentrating said energy by means of the collector 10, 20 or 30.

[0080] Step 520 of modulation of the electromagnetic energy Eray consists of modulating the electromagnetic energy Eray that has been modulated previously. The modulation is carried out either by means of the optical chopper 11 or 21, or by rotation of the photoacoustic cell 32 around its axis of rotation 329.

[0081] The step 530 of generating an acoustic wave from electromagnetic radiation 900 consists, by means of the photoacoustic effect, of converting a part of the electromagnetic energy Eray into acoustic energy Eac, within the photoacoustic cell 12, 22 or 32.

[0082] Step 540 of converting acoustic energy Eac into electrical energy Eeiec is carried out by means of the electroacoustic transducer 13, 23 or 33.

[0083] Finally, the electrical energy storage step 550 Eeiec is carried out to store said energy from the previous step.

Claims

Demands

1. A photoacoustic-electric conversion device (100, 200, 300) comprising at least one electromagnetic radiation collector (10, 20, 30) for receiving and maximizing electromagnetic energy Eray from said radiation, at least one photoacoustic cell (12, 12a, 12b, 12c, 22, 32) operationally coupled to the collector (10, 20, 30), said photoacoustic cell being configured to generate acoustic energy Eac by photoacoustic effect from the electromagnetic energy Eray wholly or partly contained in the electromagnetic radiation (900), said device further comprising at least one electroacoustic transducer (13, 23, 33) operationally coupled to the photoacoustic cell (12, 12a, 12b, 12c, 22, 32) for converting the acoustic energy Eac into an electrical energy Eeiec, and an electrical energy storage system (14, 24, 34),said device being characterized in that it converts electromagnetic energy Eray into electrical energy Ee]ec and that it stores the electrical energy Eeiec in the electrical energy storage system (14, 24, 34).

2. Device (100, 200) according to claim 1, wherein said device further comprises an optical chopper (11, 21), operationally coupled between the collector (10, 20) and the photoacoustic cell (12, 12a, 12b, 12c, 22).

3. Device (100, 200) according to claim 2, wherein the optical chopper (11, 21) is an electro-mechanical chopper or an electro-optical chopper requiring to be powered by electrical power from an energy source (15, 25).

4. Device (100, 200) according to claim 2, wherein the optical chopper (11, 21) is an opto-mechanical chopper not requiring electrical power.

5. Device (100, 200, 300) according to any one of the preceding claims, wherein the collector (10, 20, 30) comprises a plurality of lenses or reflective internal walls.

6. Device (100, 200, 300) according to any one of the preceding claims, wherein the collector (10, 20, 30) is fixed.

7. Device (100, 200, 300) according to any one of claims 1 to 5, wherein the collector (10, 20, 30) is movable.

8. Device (100, 200, 300) according to any one of the preceding claims, wherein the electroacoustic transducer (13, 23, 33) is a piezoelectric element.

9. Device (300) according to claim 1, wherein the photoacoustic cell (32) pivots about an axis of rotation (329).

10. Device (100, 200, 300) according to any one of the preceding claims, wherein the electromagnetic energy Eray is derived, either individually or in combination, from solar radiation (91), from heat emitted by a human body (92), from a light bulb (93) or from a heating system (94).

11. A method (500) of photoacousto-electric conversion operated by a photoacousto-electric conversion device (100, 200, 300) according to any one of claims 1 to 10, characterized in that the method comprises the following steps: - (510) of collecting electromagnetic energy Eray from electromagnetic radiation (900) by means of a collector (10, 20, 30) of said device; - (530) of generating an acoustic wave from the electromagnetic radiation (900) by means of at least one photoacoustic cell (12, 22, 32) of said device; and - (540) of converting the acoustic energy Eac into electrical energy EeieC, by means of at least one electroacoustic transducer (13, 23, 33) of said device.

12. Method (500) according to claim 11, said method further comprising, between the step (510) of collecting electromagnetic energy Eray and the step (530) of generating an acoustic wave, a step (520) of modulating the electromagnetic energy Eray.

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