An overturning lunar photothermal electric conversion device and conversion method

Abstract

The application discloses a flip type lunar photothermal electric conversion device and a conversion method, and relates to a photothermal electric conversion device and a conversion method. The application is used for solving the problem that a lunar base is difficult to be continuously powered during a lunar night. The application utilizes a heat accumulator integrated with a photovoltaic cell to cope with the energy shortage problem during the lunar night, realizes continuous power generation of the lunar base during a lunar day and the lunar night, and has the following advantages: firstly, the application utilizes the heat transfer characteristics of a heat pipe, and combines the flip unit integrated with the heat pipe to realize the automatic switching of the heat transfer direction, so that the heat is automatically guided and transported in the lunar day / lunar night mode, and the whole process is simple and efficient without complex valve control; and finally, the application utilizes a spectrum selective coating to realize the day / night function multiplexing of the photovoltaic cell, reduces the weight and volume of the system, and improves the integration of the whole conversion device. The application belongs to the technical field of energy supply of a lunar base.

Description

Technical Field

[0001] This invention relates to a photothermal-electric conversion device and method, specifically a flip-type lunar photothermal-electric conversion device and method, belonging to the field of lunar base energy supply technology. Background Technology

[0002] The construction and operation of a lunar base depend on a stable and reliable energy supply. Since the moon's rotation period is approximately 28 Earth days, with lunar day and lunar night each lasting about 14.75 days, this half-month-long alternation of day and night presents a fundamental challenge to the energy system: during the lunar day, solar energy is abundant, but energy reserves are needed for the lunar night; during the lunar night, there is no solar radiation, and the base equipment needs continuous power supply, while traditional solar power generation systems are completely inoperable during this period.

[0003] Currently, lunar exploration projects mainly employ a solar array combined with batteries, generating and storing electricity during the lunar day, and relying on batteries for power at night. However, batteries have limited energy density and short cycle life, making it difficult to meet long-term high-power demands. While radioisotope batteries can provide continuous power, they suffer from issues such as large weight, high cost, and safety concerns. In recent years, technologies combining thermal storage and thermoelectric power generation have attracted attention, but existing designs generally suffer from the following shortcomings:

[0004] First, the overall flipping or tracking mechanism of large concentrators is complex, consumes a lot of power, and is difficult to guarantee in terms of reliability.

[0005] Second, the switching of heat transport direction between day and night modes relies on complex valve or pipeline systems, which increases the system weight and control difficulty.

[0006] Third, the photovoltaic panels are idle during the moonlit night, and their potential as heat dissipation surfaces is not fully utilized.

[0007] Therefore, there is an urgent need for a compact and highly reliable lunar day / night photothermal-electric conversion device and conversion method to solve the problem of continuous power supply during the lunar night. Summary of the Invention

[0008] To address the shortcomings of the prior art, this invention provides a flip-type lunar photothermal-electric conversion device and conversion method.

[0009] The technical solution of the present invention is: a flip-type lunar photothermal-electric conversion device, comprising a concentrator, an integrated flip unit, and a support frame.

[0010] Both the concentrator and the support frame are installed in an unobstructed area of ​​the lunar surface, and a stepper motor is mounted on the support frame.

[0011] The integrated flip unit includes photovoltaic cells, thermoelectric generators, thermal storage devices, flipping frames, and several heat pipes.

[0012] The flipping frame is fixedly connected to the rotor of the stepper motor, and the photovoltaic cells are mounted on the flipping frame and arranged at the focal point of the concentrator.

[0013] The thermoelectric generator, heat pipe, and thermal storage are arranged sequentially on the back surface of the photovoltaic cell. The thermoelectric generator is fixed to the back surface of the photovoltaic cell, one end of the heat pipe is fixed to the thermoelectric generator, and the other end of the heat pipe is inserted into the thermal storage.

[0014] Furthermore, the surface of the photovoltaic cell is coated with a spectrally selective coating.

[0015] This invention also provides a flip-type lunar photothermal-electric conversion method, which is implemented in the following manner:

[0016] During the lunar day, the stepper motor drives the integrated flipping unit to rotate, so that the light-receiving surface of the photovoltaic cell faces the focal point of the concentrator. The photovoltaic cell converts part of the light energy into electrical energy and the rest of the light energy into heat energy. The heat energy is then transferred to the heat storage device for storage through the thermoelectric generator and heat pipe.

[0017] On a moonlit night, the stepper motor rotates the integrated flipping unit 180°, so that the back of the photovoltaic cell faces the focal point of the concentrator; the heat released by the thermal storage device heats the heat pipe, and the heat pipe transfers part of the heat to the thermoelectric generator to generate electricity, while the rest of the heat is transferred to the photovoltaic cell and dissipated into deep space through the spectrally selective coating on the surface of the photovoltaic cell.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention utilizes a thermal storage device integrated with photovoltaic cells to address the energy shortage problem during the lunar night, enabling the lunar base to generate electricity continuously during both lunar day and lunar night, fundamentally solving the energy supply problem during the lunar night.

[0020] 2. This invention utilizes the heat transfer characteristics of heat pipes and combines them with an integrated flipping unit that can flip during lunar night / lunar day to switch the positions of the two ends of the heat pipe. By utilizing the heat transfer characteristics of the heat pipe, the heat transport direction is automatically switched, so that heat is automatically guided and transported in lunar day / lunar night mode. The whole process does not require complex valve control and is simple and efficient.

[0021] 3. This invention utilizes a spectrally selective coating to enable day and night reuse of photovoltaic cells, reducing system weight and volume and improving the integration of the entire conversion device. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the invention operating during lunar daylight;

[0023] Figure 2 This is a schematic diagram of the invention operating during moonlight;

[0024] Figure 3 This is a schematic diagram of the heat storage material inside the heat storage tank 5.

[0025] In the diagram: 1. Concentrator; 2. Photovoltaic cell; 3. Thermoelectric generator; 4. Heat pipe; 5. Thermal storage device; 6. Integrated flipping unit; 8. Sintered lunar soil; 9. Original lunar soil; 11. Flipping frame; 12. Support frame; 13. Stepper motor. Detailed Implementation

[0026] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments.

[0027] Specific implementation method one: Combining Figures 1 to 3 This embodiment describes a flip-type lunar photothermal-electric conversion device, which includes a concentrator 1, an integrated flip unit 6, and a support frame 12.

[0028] Both the concentrator 1 and the support frame 12 are installed in an unobstructed area on the lunar surface. The focal point of the concentrator 1 is always facing upwards to concentrate sunlight into the focal area during lunar day. A stepper motor 13 is installed on the support frame 12. The control system of the stepper motor 13 is connected to the central control unit of the lunar base. According to the alternation of lunar day and lunar night, the control signal is automatically sent and the flipping action is executed.

[0029] The integrated flipping unit 6 is covered with multiple layers of heat insulation material to reduce heat loss to the environment. The integrated flipping unit 6 includes a photovoltaic cell 2, a thermoelectric generator 3, a heat storage device 5, a flipping frame 11, and several heat pipes 4. Preferably, the heat pipes 4 are two-phase closed thermosiphons (also known as gravity heat pipes) to ensure that the working fluid always maintains a liquid-gas phase cyclic working state throughout the entire cycle, and the heat transfer will not be interrupted due to solidification. It ensures that heat can only be transferred from the evaporation section to the condensation section. Its operation depends on the evaporation section always being below the condensation section in the direction of gravity.

[0030] The rotating frame 11 is fixedly connected to the rotor of the stepper motor 13. The photovoltaic cell 2 is mounted on the rotating frame 11 and is arranged at the focal point of the concentrator 1.

[0031] The thermoelectric generator 3, heat pipe 4, and heat storage device 5 are arranged sequentially on the back surface of the photovoltaic cell 2. The thermoelectric generator 3 is fixedly connected to the back surface of the photovoltaic cell 2, one end of the heat pipe 4 is fixedly connected to the thermoelectric generator 3, and the other end of the heat pipe 4 is inserted into the heat storage device 5.

[0032] Preferably, the heat storage device 5 has a cylindrical structure with a high-strength aluminum alloy shell. The heat storage material inside includes a sintered lunar soil molten layer 8 and a raw lunar soil layer 9 arranged sequentially from the inside to the outside. There is a vacuum interlayer cavity between the sintered lunar soil molten layer 8 and the raw lunar soil layer 9. The end of the heat pipe 4 is inserted into the sintered lunar soil molten layer 8 to ensure efficient heat transfer.

[0033] The sintered lunar regolith melt layer 8 serves as the main heat storage medium. It is prepared using in-situ lunar resources through a sintering process, resulting in a thermal conductivity of 1 W / (m•K), a latent heat of phase change of ≥300 kJ / kg, and a phase change temperature designed to be 150-200℃. The original lunar regolith layer 9 provides structural support and initial insulation, while the vacuum interlayer cavity in the middle further reduces heat loss.

[0034] Specific Implementation Method Two: Combining Figures 1 to 3 This embodiment describes a photovoltaic cell 2 as a triple-junction gallium arsenide solar cell with a photoelectric conversion efficiency of ≥30%.

[0035] Furthermore, the surface of the photovoltaic cell 2 is coated with a spectrally selective coating.

[0036] Furthermore, the transmittance of the spectrally selective coating in the 0.3-1.1μm band is ≥0.92. This setting ensures that the spectrally selective coating has high transmittance in the photovoltaic response band, so as to guarantee the power generation efficiency during the lunar day.

[0037] Furthermore, the emissivity of the spectrally selective coating in the 8-14μm band is ≥0.93. This setting ensures that the spectrally selective coating has a high emissivity in the mid-infrared band to match the infrared transparency window of the atmosphere, ensuring that heat can be directly radiated to outer space and enhancing radiative heat dissipation during the lunar night.

[0038] The other components and connections are the same as in Specific Implementation Method 1.

[0039] Specific implementation method three: Combining Figures 1 to 3 This embodiment describes a parabolic concentrator 1.

[0040] Furthermore, the concentrator 1 is a concentrator made of carbon fiber composite material.

[0041] Furthermore, the focal length of the condenser 1 is 1.5m, the aperture is 3m, and the light concentration ratio is more than 100 times.

[0042] Furthermore, the surface of the concentrator 1 is coated with a high-reflectivity metal reflective film; preferably, an aluminum-coated reflective film with a reflectivity ≥0.95 is selected.

[0043] The other components and connections are the same as in specific implementation method one or two.

[0044] Specific implementation method four: Combination Figures 1 to 3 This embodiment describes a thermoelectric generator 3 made of bismuth telluride-based thermoelectric material. The contact surfaces between the thermoelectric generator 3 and the photovoltaic cell 2, as well as between the thermoelectric generator 3 and the heat pipe 4, are filled with thermally conductive silicone grease to reduce contact thermal resistance. The thermoelectric generator 3 converts the temperature difference between its two sides into electrical energy, supplementing the photovoltaic cell 2. Other components and connections are the same as in specific embodiments one, two, or three.

[0045] Specific Implementation Method Five: Combining Figures 1 to 3 This embodiment describes a flip-type lunar photothermal-electric conversion method, which is implemented in the following manner:

[0046] During the lunar day, the stepper motor 13 drives the integrated flipping unit 6 to rotate, so that the light-receiving surface of the photovoltaic cell 2 faces the focal point of the concentrator 1 (the stepper motor 13 has a self-locking capability, and its rotor can be kept stationary at any position by controlling the pulse signal). The photovoltaic cell 2 converts part of the light energy into electrical energy and the rest of the light energy into heat energy. The heat energy is transferred to the heat storage tank 5 for storage through the thermoelectric generator 3 and the heat pipe 4 in sequence. In this mode, the end of the heat pipe 4 that is fixed to the thermoelectric generator 3 is the evaporation section, and the end of the heat pipe 4 that is inserted into the heat storage tank 5 is the condensation section. The heat is transferred from bottom to top.

[0047] On a moonlit night, stepper motor 13 rotates integrated flip unit 6 180°, so that the back surface of photovoltaic cell 2 faces the focal point of concentrator 1; the heat released by thermal storage 5 heats heat pipe 4, and heat pipe 4 transfers part of the heat to thermoelectric generator 3 to generate electricity, and the rest of the heat is transferred to photovoltaic cell 2, which is then radiated into deep space through the spectrally selective coating on the surface of photovoltaic cell 2; in this mode, the end of heat pipe 4 that is fixed to thermoelectric generator 3 is the condensation section, and the end of heat pipe 4 that is inserted into thermal storage 5 is the evaporation section, and the heat is transferred from top to bottom.

[0048] The other components and connections are the same as those in specific implementation methods one, two, three, or four.

[0049] Example

[0050] (1) Example of running in lunar daytime mode:

[0051] Once solar radiation reaches the operating threshold, the system enters lunar day mode.

[0052] The integrated flip unit 6 is positioned with the light-receiving surface of the photovoltaic cell 2 facing the focal point of the concentrator 1. At this time, the end of the heat pipe 4 that is fixed to the thermoelectric generator 3 is the evaporation section, and the end of the heat pipe 4 that is inserted into the heat storage unit 5 is the condensation section.

[0053] Concentrator 1 focuses sunlight onto photovoltaic cell 2, which generates approximately 500W of power. The waste heat (temperature approximately 80°C) generated by photovoltaic cell 2 is conducted from bottom to top to thermoelectric generator 3, creating a temperature difference of approximately 50°C on both sides of thermoelectric generator 3, with an output power of approximately 20W.

[0054] The heat continues to be transferred upwards to the evaporation section of heat pipe 4. The heat pipe starts up, and the working fluid absorbs heat and evaporates in the evaporation section. The steam rises to the condensation section, releases heat and condenses. The liquid film flows back to the evaporation section along the pipe wall, completing the heat transport. After the heat enters the heat storage tank 5, the temperature of the heat storage material gradually rises. When it reaches the phase change temperature, it begins to melt and store heat until the temperature of the heat storage module rises to 200°C, completing the heat storage process.

[0055] (2) Example of running in moonlight mode:

[0056] After the moonlit night falls, the stepper motor 13 drives the integrated flipping unit 6 to flip 180°, so that the back of the photovoltaic cell 2 faces the focal point of the concentrator 1. At this time, the end of the heat pipe 4 that is fixed to the thermoelectric generator 3 is the condensation section, and the end of the heat pipe 4 that is inserted into the heat storage tank 5 is the evaporation section.

[0057] The thermal storage device 5 begins to slowly release heat, as the storage material condenses and releases heat, with the temperature gradually decreasing from 200°C. This heat activates the evaporation section of the heat pipe 4, where the working fluid absorbs heat and evaporates. The vapor is transferred upwards to the condensation section, releasing heat and condensing. The liquid film flows back along the pipe wall to the evaporation section, completing the heat transport. Heat enters the hot end of the thermoelectric generator 3, while the cold end faces deep space, creating a temperature difference of approximately 200°C. The thermoelectric generator outputs approximately 50W. Waste heat continues to transfer to the back surface of the photovoltaic cell 2, raising its surface temperature to -30°C. This heat is then dissipated into deep space through the high-emissivity, spectrally selective coating on its surface. As the temperature of the thermal storage device 5 gradually decreases, the temperature difference between the two sides of the thermoelectric generator 3 gradually decreases, and the power generation correspondingly decreases until the stored heat is completely released. The photothermal-electric conversion device then enters a standby state, awaiting the arrival of the next lunar day.

[0058] Throughout the lunar night, the evaporation section of heat pipe 4 remains coupled to the heat storage unit 5, with the temperature at the coupling point gradually decreasing from 200°C. Although the condensation section faces a low-temperature environment, its temperature remains above the freezing point of the working fluid due to continuous heat transport, preventing solidification.

[0059] The present invention has been disclosed above with reference to preferred embodiments, but it is not intended to limit the present invention. Any simple modifications, equivalent changes and alterations made by those skilled in the art to the above embodiments without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A flip-type lunar photothermal-electric conversion device, characterized in that: It includes a condenser (1), an integrated flipping unit (6), and a support frame (12). The concentrator (1) and the support frame (12) are both installed in an unobstructed area on the lunar surface, and a stepper motor (13) is installed on the support frame (12). The integrated flipping unit (6) includes a photovoltaic cell (2), a thermoelectric generator (3), a heat storage device (5), a flipping frame (11), and several heat pipes (4). The rotating frame (11) is fixedly connected to the rotor of the stepper motor (13), the photovoltaic cell (2) is mounted on the rotating frame (11), and the photovoltaic cell (2) is arranged at the focal position of the concentrator (1); The thermoelectric generator (3), heat pipe (4) and heat storage device (5) are arranged sequentially on the back surface of the photovoltaic cell (2), and the thermoelectric generator (3) is fixed to the back surface of the photovoltaic cell (2). One end of the heat pipe (4) is fixed to the thermoelectric generator (3), and the other end of the heat pipe (4) is inserted into the heat storage device (5).

2. The flip-type lunar photothermal-electric conversion device according to claim 1, characterized in that: The surface of the photovoltaic cell (2) is coated with a spectrally selective coating.

3. The flip-type lunar photothermal-electric conversion device according to claim 2, characterized in that: The photovoltaic cell (2) is a triple-junction gallium arsenide solar cell.

4. The flip-type lunar photothermal-electric conversion device according to claim 3, characterized in that: The spectrally selective coating has a transmittance of ≥0.9 in the 0.3-1.1 μm wavelength range.

5. A flip-type lunar photothermal-electric conversion device according to claim 4, characterized in that: The spectrally selective coating has an emissivity ≥0.9 in the 8-14 μm band.

6. The flip-type lunar photothermal-electric conversion device according to claim 5, characterized in that: The concentrator (1) is a parabolic concentrator.

7. A flip-type lunar photothermal-electric conversion device according to claim 6, characterized in that: The concentrator (1) is a concentrator made of carbon fiber composite material.

8. A flip-type lunar photothermal-electric conversion device according to claim 7, characterized in that: The surface of the concentrator (1) is coated with a metal reflective film.

9. A flip-type lunar photothermal-electric conversion device according to claim 8, characterized in that: The thermoelectric generator (3) is a thermoelectric generator made of bismuth telluride-based thermoelectric material.

10. A conversion method using the apparatus of claim 9, characterized in that: During the daytime, the stepper motor (13) drives the integrated flipping unit (6) to rotate, so that the light-receiving surface of the photovoltaic cell (2) faces the focal point of the concentrator (1). The photovoltaic cell (2) converts part of the light energy into electrical energy and the rest of the light energy into heat energy. The heat energy is transferred to the heat storage device (5) for storage through the thermoelectric generator (3) and the heat pipe (4). On a moonlit night, the stepper motor (13) rotates the integrated flip unit (6) 180° so that the back of the photovoltaic cell (2) faces the focal point of the concentrator (1); the heat released by the heat storage device (5) heats the heat pipe (4), and the heat pipe (4) transfers part of the heat to the thermoelectric generator (3) to generate electricity, and the rest of the heat is transferred to the photovoltaic cell (2), which is then radiated into deep space through the spectrally selective coating on the surface of the photovoltaic cell (2).

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