Energy storage solar thermal photovoltaic system using near-field thermal radiation technology

Abstract

The present invention discloses an energy storage type solar thermal photovoltaic system using near-field thermal radiation technology, including components such as an absorption cavity, an absorber, a heat exchanger, a heat storage chamber, a radiator, and a photovoltaic cell. The absorption cavity can reflect sunlight to the absorber, and the absorber absorbs solar radiation and heats itself; the heat exchanger can transfer the heat of the absorber to the heat storage chamber, heat the phase change material to achieve energy storage; the radiator is fixed on the heat storage chamber to absorb heat from the heat storage chamber and heat itself to a higher temperature, and emits characteristic thermal radiation to the photovoltaic cell group; the radiator and the photovoltaic cell are separated by a nano vacuum gap; there is a radiator on the back of the photovoltaic cell to control the photovoltaic cell at the optimal working temperature. This system uses near-field technology and metamaterial technology to transform solar radiation, improves the radiation amount received by the photovoltaic cell side and the usable proportion, and improves the system efficiency of the traditional energy storage type solar thermal photovoltaic system; using energy storage technology, a stable energy supply is achieved that is not affected by weather factors.

Description

Technical Field

[0001] The present invention relates to the field of solar thermal photovoltaic power supply, and in particular to a near-field energy storage solar thermal photovoltaic system. Background Art

[0002] Solar energy, as a clean energy source, is both primary and renewable, offering advantages unmatched by mineral energy sources. The development and utilization of solar energy is of vital importance for conserving conventional energy, protecting the natural environment, and mitigating climate change. Solar photovoltaic technology is considered one of the most promising technologies and is currently in widespread use worldwide. Solar radiation ranges from 0 to 2500 nanometers, while conventional photovoltaic silicon cells absorb light in the wavelength range of only 300 to 1200 nanometers. This leaves a significant number of incident photons with energies below the band gap unused, resulting in low photovoltaic efficiency. The highest conversion efficiency is only 32%, and the current, large-scale solar photovoltaic conversion efficiency is only 21.8%. Energy-storage solar thermal photovoltaic systems, as a potential high-efficiency solar energy utilization technology, have attracted considerable research attention in recent years. An ideal energy-storage solar thermal photovoltaic system, through the combined action of an absorber and a radiator, could increase solar energy conversion efficiency to 54%.

[0003] Therefore, it is necessary to provide a solar thermal photovoltaic system with a simple system, high efficiency, and stable energy supply without being disturbed by weather factors. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a near-field energy storage solar thermal photovoltaic system.

[0005] The present invention discloses an energy storage solar thermal photovoltaic system using near-field thermal radiation technology, which includes an absorption chamber, an absorber, a heat exchanger, a heat storage chamber, a radiator, and a photovoltaic cell. The absorption chamber is arranged on the top of the absorber, and the top of the absorption chamber is provided with at least one opening for sunlight to enter. A reflector is arranged on the inner wall of the absorption chamber for reflecting sunlight back to the absorber.

[0006] The absorber includes a single / multi-layer ultra-thin substrate and a periodic nanostructure arranged on the upper surface of the ultra-thin substrate; the heat exchanger is composed of a heat pipe, and the heat exchanger is used to enhance the heat exchange between the absorber and the heat storage chamber, and between the heat storage chamber and the radiator. The heat storage chamber is provided with a phase change material. The radiator includes a single / multi-layer ultra-thin substrate and a periodic nanostructure arranged on the lower surface of the ultra-thin substrate; the photovoltaic cell is located below the radiator, and the radiator emits characteristic thermal radiation to the photovoltaic cell. The radiator and the photovoltaic cell are separated by a nano vacuum gap, and a heat sink is provided on the back of the photovoltaic cell.

[0007] As a preferred embodiment of the present invention, the absorption cavity is narrow at the top and wide at the bottom, with the opening at the top; its wall surface is a continuous curved surface or its wall surface is composed of several planes and / or curved surfaces connected together; reflectors are installed around the inner wall surface of the absorption cavity to reflect the radiation reflected by the absorber back to the absorber again.

[0008] As a preferred embodiment of the present invention, the absorber surface features microtexture and nanostructures to enhance absorption and reduce reflection. Metamaterial technology is also employed to improve full-band absorption performance. The absorber is located at the bottom of the absorption cavity, which is connected to the heat storage chamber. The ultrathin substrate has a thickness of 0.01-100 microns. The period of the periodic nanostructures ranges from 0.01-10 microns, and the nanostructures themselves (maximum dimension) range from 10-1000 nanometers. The nanostructures contain cavities with a minimum dimension of 10 nanometers. The nanostructures are composed of multiple layers of alternating materials along the thickness direction.

[0009] As a preferred embodiment of the present invention, the heat exchanger includes a first heat pipe group and a second heat pipe group. The first heat pipe group is disposed within the phase change material, with its evaporation section in contact with the back of the absorber; the second heat pipe group is disposed within the phase change material, with its condensation section in contact with the back of the radiator. The first and second heat pipe groups do not contact each other within the phase change material. The first and second heat pipe groups use materials such as lithium (1374°C), calcium (1440°C), and antimony (1440°C) as working fluids, achieving efficient heat exchange between the absorber, phase change material, and radiator at ultra-high temperatures.

[0010] As a preferred solution of the present invention, the phase change temperature of the working medium in the first heat pipe group is higher than the phase change temperature of the working medium in the second heat pipe group.

[0011] As a preferred embodiment of the present invention, the phase change temperature of the phase change material in the heat storage chamber needs to be between the operating temperatures of the first heat pipe and the second heat pipe. The phase change material in the heat storage chamber can be made of high-temperature phase change materials such as Cu (1083°C), MgF2 (1263°C), Si (1414°C), Ni (1455°C), Be (1182°C), B (1282°C), and Sc (1534°C). These materials have high phase change temperatures and phase change enthalpy, enabling ultra-high temperature and high energy density phase change heat storage. The phase change material in the heat storage chamber can be doped with carbon or other nanoparticles to improve the thermal conductivity of the phase change material.

[0012] As a preferred embodiment of the present invention, the radiator is located at the bottom of the heat storage chamber. The ultrathin substrate has a thickness of 0.01-100 microns. The period of the periodic nanostructure is 0.01-10 microns, and the nanostructure itself (maximum dimension) is 10-1000 nanometers. The nanostructure has a cavity within it, with a minimum dimension of 10 nanometers. The nanostructure is composed of multiple layers of materials alternating in thickness.

[0013] As a preferred embodiment of the present invention, the thickness of the nano vacuum gap is 150-3500 nanometers, which can achieve near-field thermal radiation, thereby improving thermal radiation, power generation efficiency and output power density. The photovoltaic cell uses a low-bandgap cell and its series / parallel connection.

[0014] As a preferred solution of the present invention, the system further comprises a concentrator, which is arranged above the absorber. The concentrator concentrates solar radiation and reflects or transmits it into the absorption cavity.

[0015] As a preferred solution of the present invention, the system further comprises a filtering device, which is arranged on the surface of the photovoltaic cell and is used to selectively filter the radiation energy radiated by the radiator.

[0016] The present invention has the following beneficial effects:

[0017] Since the system of the present invention uses solar energy as a heat source, it has the advantages of high heat utilization efficiency, high radiator temperature, no environmental pollution, and no fuel cost.

[0018] The system of the present invention can utilize concentrated sunlight. The absorber absorbs highly concentrated solar radiation and heats itself. The heat is then transferred to the high-temperature phase change material and radiator in the heat storage chamber through a heat exchange device. The selective radiator, heated to a high temperature, emits thermal radiation to the photovoltaic cell, which absorbs the thermal radiation and converts it into electrical energy. Thus, the near-field-energy storage solar thermal photovoltaic power generation device combines solar absorption technology, thermophotovoltaic technology, near-field thermal radiation technology, and metamaterial technology. It has a simple and stable system structure, can better adapt to complex and changing working environments, and can stably supply energy without being affected by weather factors. It is highly efficient, fuel-free, sustainable, and pollution-free. It has the advantages of simple structure, high system efficiency, high output power density, high safety, and the ability to store heat and energy, realizing a new and efficient use of solar energy.

[0019] Since the present invention utilizes near-field radiation, the system design has a small size, compact structure, high unit energy density, and can be miniaturized or micro-miniaturized; due to the existence of the near-field effect, the radiation intensity increases sharply, and high system efficiency can be achieved; due to the application of energy storage technology, the system can be unaffected by weather factors and can provide stable energy 24 hours a day. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a near-field energy storage solar thermal photovoltaic power generation device in a specific embodiment of the present invention;

[0021] Figure 2 This is a schematic structural diagram of a metamaterial radiator / absorber in a specific embodiment of the present invention; DETAILED DESCRIPTION

[0022] The present invention will be further described and illustrated below in conjunction with specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflict.

[0023] The present invention discloses an energy storage solar thermal photovoltaic system using near-field thermal radiation technology, which includes an absorption chamber 2, an absorber 4, a heat exchanger 6, a heat storage chamber 5, a radiator 9 and a photovoltaic cell 10. The absorption chamber 2 is arranged on the top of the absorber 4, and the top of the absorption chamber 2 is provided with at least one opening for sunlight to enter. A reflector 3 is arranged on the inner wall of the absorption chamber 2 for reflecting sunlight back to the absorber 4.

[0024] The absorber 4 comprises a single / multi-layer ultrathin substrate 41 and a periodic nanostructure 42 disposed on the upper surface of the ultrathin substrate. The heat exchanger 6 comprises a heat pipe and is used to enhance heat exchange between the absorber 4 and the heat storage chamber 5, and between the heat storage chamber 5 and the radiator 9. The heat storage chamber 5 is provided with a phase change material. The radiator 9 comprises a single / multi-layer ultrathin substrate and a periodic nanostructure disposed on the lower surface of the ultrathin substrate. A photocell 10 is located below the radiator 9, which emits characteristic thermal radiation toward the photocell 10. The radiator 9 is separated from the photocell 10 by a nanometer vacuum gap, and a heat sink is disposed on the back of the photocell 10. As a preferred embodiment of the present invention, the absorption chamber 2 is narrow at the top and wide at the bottom, with an opening at the top. Its walls are continuous curved surfaces or are composed of a plurality of flat and / or curved surfaces connected together. Reflectors are mounted around the inner walls of the absorption chamber 2 to reflect radiation reflected by the absorber 4 back to the absorber 4.

[0025] The near-field energy storage solar thermal photovoltaic system of this embodiment includes an absorber cavity in the shape of an open cone with a small opening at the top to receive highly concentrated solar radiation. Reflectors are mounted on the inner surfaces of the surrounding sides to reflect radiation reflected by the absorber back into the absorber. The absorber cavity of this experimental device can be quasi-conical (e.g., the absorber cavity is arranged in a cone, regular tetrahedron, triangular pyramid, etc., with the absorber arranged on the bottom surface) or quasi-spherical (e.g., the solar concentrator is arranged in a spherical shape with a small opening, the absorber is arranged in an arc shape on the inner surface opposite the small opening, and reflectors are arranged on the remaining inner surfaces).

[0026] In a specific embodiment of the present invention, the absorber is located at the bottom of the absorption cavity, and the bottom of the absorber is connected to the heat storage chamber. The nanostructure can be a periodic non-conical multi-layer cavity type. The multi-layer structure and the cavity structure can greatly improve the absorption performance of the absorber in the solar radiation band. Figure 2As shown, the absorber of the present invention uses a periodic multilayer ring as an example. The inner radius and thickness of the ring must be on the nanometer scale (less than 1000 nanometers). The multilayer structure can be an alternating arrangement of W-Al2O3-W-Al2O3, with 12 layers (generally 3-50 layers). High-temperature resistant materials such as platinum, molybdenum, and boron can also be used. The thickness of the ultra-thin substrate is 0.05 (0.01-100) microns.

[0027] like Figure 1 As shown, in a specific embodiment of the present invention, the heat exchanger 6 includes a first heat pipe group and a second heat pipe group. The first heat pipe group is arranged in the phase change material, and its evaporation section is in contact with the back of the absorber; the second heat pipe group is arranged in the phase change material, and its condensation section is in contact with the back of the radiator; the first heat pipe group and the second heat pipe group do not contact each other inside the phase change material.

[0028] In one embodiment of the present invention, the phase change temperature of the working fluid in the first heat pipe group is higher than the phase change temperature of the working fluid in the second heat pipe group. The working fluid in the first heat pipe group is calcium (1484°C), and the working fluid in the second heat pipe group is lithium (1374°C). The phase change temperature of the phase change material in the heat storage chamber must be between the operating temperatures of the first and second heat pipes. The selected phase change material is silicon (1410°C).

[0029] In a specific embodiment of the present invention, the radiator is located at the bottom of the heat storage chamber, and the thickness of the ultra-thin substrate is 0.01-100 microns; the nanostructure can be a periodic conical multi-layer cavity type, the temperature of the ultra-high temperature radiator is usually 1000-2000°C, and its blackbody radiation spectrum is in the range of 500-4000 nanometers. The multi-layer structure and cavity structure can greatly improve the absorption rate of the absorber, and the conical structure and the expanded cavity can, to a certain extent, expand the spectrum segment with high emissivity to the band required by the radiator; taking the periodic multi-layer truncated cone metamaterial radiator as an example, the spectral range of the radiator's high emissivity can be increased by increasing the radius of the ring. The inner circle radius and thickness of each layer of the truncated cone must be in the nanoscale (less than 1000 nanometers); the multi-layer structure material can be Si3N4-W-Si3N4 arranged alternately, the number of layers can be 3-50 layers, and the material can also be selected from high-temperature resistant materials such as platinum, molybdenum, and boron.

[0030] In a specific embodiment of the present invention, the thickness of the nano vacuum gap 7 is 150-3500 nanometers. The photovoltaic cells are low-bandgap cells and their series / parallel configurations. The high-performance photovoltaic cells are GaSb, which has a low bandgap and is well compatible with the selected high-performance selective radiator.

[0031] In a specific embodiment of the present invention, the system further includes a concentrator disposed above the absorber, which concentrates solar radiation and reflects or transmits it into the absorption cavity. The system also includes a filter device disposed on the surface of the photovoltaic cell and configured to selectively filter the radiant energy emitted by the radiator, thereby ensuring that the spectrum of radiation absorbed by the photovoltaic module more closely matches the external quantum efficiency curve of each photovoltaic module.

[0032] In a specific embodiment of the present invention, the radiator uses high specific heat and low cost water as the working medium, and adopts an internal thread structure to increase the turbulence of the water during the flow process, thereby enhancing heat exchange.

[0033] The solar radiation is concentrated and enters the absorption chamber through a small opening at the top of the absorber. Some of this radiation is reflected by the absorber, while the absorber also releases thermal radiation at high temperatures. Mirrors arranged on the sides of the absorption chamber repeatedly reflect this unused thermal radiation back to the absorber, achieving full absorption of the solar radiation.

[0034] The housing and other supporting components of the system of the present invention can be made of high-performance high-temperature resistant materials, can be used repeatedly, are not affected by the surrounding environment, and can be provided with a thermal insulation layer according to the situation.

[0035] Solar radiation is received by the absorber and heats the absorber itself. A reflector placed on the inner surface of the absorber reflects unabsorbed radiation back to the absorber, repeatedly heating the absorber and achieving full absorption of the solar radiation. A heat exchanger is placed on the back of the absorber, efficiently transferring heat from the absorber to the phase-change thermal storage material, which then transfers the heat from the phase-change thermal storage material to the radiator. The phase-change thermal storage material receives heat from the absorber and stores it at a constant temperature through phase change, providing a stable heat source for the radiator. The radiator absorbs heat from the phase-change material, heats itself to a high temperature, and emits specific thermal radiation to the photovoltaic cell. Because the distance between the radiator and the photovoltaic cell can be controlled within the near-field range (less than 3500 nanometers), the radiation can be transmitted to the photovoltaic cell in the form of evanescent waves. The photovoltaic cell receives the specific radiation from the radiator and generates electricity through the photoelectric effect. The radiator is a water-cooled radiator, but other working fluid heat dissipation devices can also be used. Internal threads and other structures are incorporated into the cooling pipes to enhance heat exchange. The photovoltaic cell assembly transfers excess heat energy to the cooling device, which disperses this heat into the environment. An intelligent temperature control system can be set up to control the operating temperature of the photovoltaic cell within the optimal range by adjusting the water flow.

[0036] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An energy storage solar thermal photovoltaic system using near-field thermal radiation technology, characterized in that: The invention comprises an absorption chamber, an absorber, a heat exchanger, a heat storage chamber, a radiator and a photocell, wherein the absorption chamber is arranged on the top of the absorber, the top of the absorption chamber is provided with at least one opening for sunlight to enter, and a reflector for reflecting sunlight back to the absorber is arranged on the inner wall surface of the absorption chamber; The absorber comprises a single / multi-layer ultra-thin substrate and a periodic nanostructure arranged on the upper surface of the ultra-thin substrate; the heat exchanger is composed of a heat pipe, and the heat exchanger is used to strengthen the heat exchange between the absorber and the heat storage chamber, and between the heat storage chamber and the radiator, and the heat storage chamber is provided with a phase change material, and the radiator comprises a single / multi-layer ultra-thin substrate and a periodic nanostructure arranged on the lower surface of the ultra-thin substrate; the photocell is located below the radiator, and the radiator emits characteristic heat radiation to the photocell, and the radiator and the photocell are separated by a nano vacuum gap, and a heat sink is provided on the back of the photocell; The absorption cavity is narrow at the top and wide at the bottom, with the opening located at the top; Its wall surface is a continuous curved surface or its wall surface is composed of a number of planes and / or curved surfaces connected together; reflectors are installed around the inner wall surface of the absorption cavity to reflect the radiation reflected by the absorber back to the absorber again.

2. The energy storage solar thermal photovoltaic system using near-field thermal radiation technology as claimed in claim 1, characterized in that: The absorber is located at the bottom of the absorption cavity, and the bottom of the absorber is connected to the heat storage chamber. The thickness of the ultra-thin substrate is 0.01-100 microns; the period of the periodic nanostructure is 0.01-10 microns, and the size of the nanostructure itself is 10-1000 nanometers; there is a cavity inside the nanostructure, and the minimum size of the cavity is 10 nanometers. The nanostructure is composed of multiple layers of materials alternately stacked in the thickness direction.

3. The energy storage solar thermal photovoltaic system using near-field thermal radiation technology as claimed in claim 1, characterized in that: The heat exchanger includes a first heat pipe group and a second heat pipe group. The first heat pipe group is arranged in the phase change material, and its evaporation section is in contact with the back of the absorber; the second heat pipe group is arranged in the phase change material, and its condensation section is in contact with the back of the radiator; the first heat pipe group and the second heat pipe group are not in contact inside the phase change material.

4. The energy storage solar thermal photovoltaic system using near-field thermal radiation technology as claimed in claim 3, characterized in that: The phase change temperature of the working medium in the first heat pipe group is higher than the phase change temperature of the working medium in the second heat pipe group.

5. The energy storage solar thermal photovoltaic system using near-field thermal radiation technology as claimed in claim 3, characterized in that: The phase change temperature of the phase change material in the heat storage chamber needs to be between the operating temperatures of the first heat pipe and the second heat pipe.

6. The energy storage solar thermal photovoltaic system using near-field thermal radiation technology as claimed in claim 1, characterized in that: The radiator is located at the bottom of the heat storage chamber, the thickness of the ultra-thin substrate is 0.01-100 microns; the period of the periodic nanostructure is 0.01-10 microns, and the size of the nanostructure itself is 10-1000 nanometers; there is a cavity inside the nanostructure, the minimum size of the cavity is 10 nanometers, and the nanostructure is composed of multiple layers of materials alternately stacked in the thickness direction.

7. The energy storage solar thermal photovoltaic system using near-field thermal radiation technology as claimed in claim 1, characterized in that: The thickness of the nano vacuum gap is 150-3500 nanometers; the photocell is a low energy gap band cell and its series / parallel connection form.

8. The energy storage solar thermal photovoltaic system using near-field thermal radiation technology as claimed in claim 1, characterized in that: The system further comprises a concentrator, which is arranged above the absorber and collects solar radiation and reflects or transmits the solar radiation into the absorption cavity.

9. The energy storage solar thermal photovoltaic system using near-field thermal radiation technology as claimed in claim 1, characterized in that: The system further comprises a filter device, which is arranged on the surface of the photocell and is used for selectively filtering the radiation energy radiated by the radiator.

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