Solar passive refrigeration device utilizing solid-liquid phase change

Abstract

The invention discloses a solar passive refrigeration device utilizing solid-liquid phase change. The device is mainly composed of a PCM cold storage station, a power generation-refrigeration comprehensive plate, a liquid phase heat exchange pipeline and an integrated circuit control system. The PCM cold storage station is filled with phase change materials to wrap the two heat transfer spiral copper pipes. A solar power generation panel is fixed on one side of the power generation-refrigeration integrated board, a radiation cooling film is pasted on the other side, and a single-inlet single-outlet multi-branch copper pipeline is arranged in the power generation-refrigeration integrated board. The liquid-phase heat exchange pipeline is connected with the multi-branch copper pipeline in the comprehensive plate and the spiral copper pipe in the cold storage station, and a heat preservation material is laid on an external flexible pipe section. The integrated circuit control system comprises light, a temperature and humidity sensor, an inverter, a storage battery, a stepping motor and a water pump. Sensor data is used for switching modes and adjusting water pump power, a stepping motor drives a comprehensive board and a water pump to drive working medium circulation through a gear, a solar power generation panel supplies power to the device through an inverter and a storage battery, and passive refrigeration working circulation is achieved.

Description

[0001] The embodiments of the present application belong to the technical field of passive refrigeration, and in particular relate to a device using solid-liquid phase change technology. Background Art

[0002] Currently, the global refrigeration demand has been soaring sharply with climate change and urbanization. According to the prediction of the International Energy Agency, the energy consumption of air-conditioning refrigeration in 2050 will reach three times that of the current level. The traditional compression refrigeration technology faces two core problems: one is the pressure of ozone layer protection at the environmental level, and the other is the risk of aggravating the greenhouse effect at the climate level. The energy conversion efficiency of such equipment is low, and a large amount of greenhouse gases will be emitted during operation, directly exacerbating global warming. Moreover, in remote areas, off-grid scenarios and emergency refrigeration, traditional active refrigeration equipment is limited by the difficulties in grid connection and high operation and maintenance costs, and it is difficult to meet the distributed refrigeration demand.

[0003] In this patent, in the wavelength band of 8-13μm where the absorption of long-wave radiation by the natural atmosphere is weak, the radiation energy of an object can pass through the atmosphere more smoothly and radiate heat into outer space. The principle that the temperature of the deep space in the universe is close to absolute zero is utilized to achieve radiative refrigeration. At the same time, high latent heat phase change materials are used to store and release the cold energy obtained above. The two are combined to form a refrigeration-cooling storage working cycle, solving the problems that the refrigeration device in the prior art requires power support and pollutes the environment during operation. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a solar passive refrigeration device that utilizes solid-liquid phase change, which includes four major modules: a PCM cold storage station, a power generation and refrigeration integrated board, a liquid phase heat exchange pipeline, and an integrated circuit control system. A radiation cooling film is affixed to the back of the power generation and refrigeration integrated board. This technology is based on the basic principle of the second law of thermodynamics and uses the characteristic of outer space being close to absolute zero as a natural cold source to achieve spontaneous heat transfer. There is a specific "atmospheric window" in the atmosphere, namely the 8-13μm band. Within this band, electromagnetic waves can penetrate the atmosphere with low loss and efficiently radiate heat into outer space. Moreover, the infrared radiation peak of a black body on the ground at normal temperature corresponds exactly to this "atmospheric window" band, providing ideal conditions for passive heat dissipation. The film utilizes an innovative two-layer structure: the upper layer utilizes femtosecond laser processing to create nanoscale grooves on the PET material surface, enhancing the film's thermal radiation capabilities in the 8-13μm wavelength range. The lower layer is coated with an Ag-coated silicon substrate, which exhibits high reflectivity in the 0.2-3μm region where solar radiation is concentrated, effectively blocking solar heat absorption. This synergistic design ensures the film combines high solar reflectivity with strong infrared radiation. During operation, the device transmits internal heat to space as infrared radiation through an "atmospheric window," achieving passive cooling without requiring additional energy input. This film utilizes the high latent heat of phase-change materials. As the film cools, its temperature continuously decreases. Once the freezing point of the phase-change material is reached, it begins to transition from liquid to solid. During this solidification process, the material releases a significant amount of latent heat. While releasing this latent heat, the material continuously absorbs external cold, storing it internally as latent heat. When the outside temperature rises, the solid-state phase-change material, which has stored cold, begins to absorb heat. Once it reaches its melting point, it transforms from solid to liquid. During this process, the phase-change material absorbs heat from the surrounding environment, lowering the ambient temperature and releasing the previously stored cold, thereby releasing cold and regulating the ambient temperature. The combination of the radiant cooling membrane, which passively cools without energy consumption, the PCM phase-change material, which stores cold, and the liquid-phase heat exchange piping, which improves heat exchange efficiency, effectively solves the problems encountered in the prior art.

[0005] In order to solve the above technical problems, the technical solution of a solar passive refrigeration device using solid-liquid phase change provided in the embodiment of the present application is as follows:

[0006] The embodiment of the present application discloses a solar passive refrigeration device utilizing solid-liquid phase change, which includes four major modules: a PCM cold storage station, a power generation-refrigeration integrated board, a liquid phase heat exchange pipeline, and an integrated circuit control system.

[0007] In a preferred embodiment of any of the above solutions, the PCM cold storage station includes a PCM chamber and a heat transfer spiral copper tube. Paraffin wax is filled in the PCM chamber as the phase change material. The paraffin wax used is a low melting point wax with a melting point of 25 °C, and its phase change enthalpy is 1.6×10 5 J / Kg. In the PCM chamber, the phase change material paraffin wax surrounds the two heat transfer spiral copper tubes. For the convenience of pipeline installation, the PCM cold storage station adopts a flip cover structure and designs two positioning through holes at the lower part of its two side faces to fix the heat transfer spiral copper tubes.

[0008] In a preferred embodiment of any of the above solutions, the power generation - refrigeration integrated board includes a solar power generation board and a radiative cooling film. A solar power generation board that completely matches its size is fixed on the outer side of the power generation - refrigeration integrated board, and a radiative cooling film is pasted on the other side. Inside the power generation - refrigeration integrated board, a structure of multi - branch copper pipelines is adopted, with single - port inlet and single - port outlet. The power generation - refrigeration integrated board adopts a detachable structure. Bolts are used to fix the side face to the upper and lower faces, and there is a positioning through hole in the center of the side face. By disassembling the side face, it is convenient to install the multi - branch copper pipelines. Both ends of the pipelines extend out through the positioning through holes on both side faces of the power generation - refrigeration integrated board and are connected to flexible tubes.

[0009] In a preferred embodiment of any of the above solutions, the liquid - phase heat exchange pipeline includes the multi - branch copper pipelines of the power generation - refrigeration integrated board, the heat transfer spiral copper tubes in the PCM cold storage station, and a circulation loop composed of a water pump and flexible tubes. The multi - branch copper pipelines in the power generation - refrigeration integrated board body are fixed inside it through the through holes on the side face of the power generation - refrigeration integrated board. The heat transfer spiral copper tubes in the PCM cold storage station are also fixed through the through holes on the side face of the PCM cold storage station. The multi - branch copper pipelines and the heat transfer spiral copper tubes are connected by using flexible tubes, and thermal insulation materials are pasted on the flexible tubes outside the power generation - refrigeration integrated board and the PCM cold storage station to reduce temperature loss.

[0010] In a preferred embodiment of any of the above solutions, the integrated circuit control system includes an environmental information acquisition system, an information log recording system, and a control terminal. The environmental information acquisition system and the information log recording system are installed on the storage rack of the box storing the phase change material. There are a light sensor and multiple temperature sensors to collect environmental light information and temperature and humidity information respectively, and collect the external environmental state of the system. The power generation mode and the refrigeration mode are switched according to the light conditions, and the power of the circulation pump is adjusted according to the temperatures of the power generation - refrigeration integrated board and the PCM cold storage station.

[0011] In a preferred embodiment of any of the above solutions, the control terminal includes an inverter, a storage battery, a servo motor, and a circulation pump. The motor shaft of the servo motor and one end of the multi-branch copper pipeline are matched through a pair of spur cylindrical gears, so that the power generation-refrigeration integrated board can rotate following the stepping motor, and the stepping motor is placed on the storage rack of the storage phase change material box. The stepping motor is controlled by a control board, and the flipping of the power generation-refrigeration integrated board is controlled according to the feedback of the collected light information and temperature and humidity information. The water pump is connected to the flexible pipe connecting the multi-branch copper pipeline and the heat transfer spiral copper pipe through a joint and is placed on the storage rack. One end of the inverter is connected to the solar panel through a wire, and the other end is connected to the stepping motor through a wire and is placed on the storage rack. One pole of the storage battery is connected to the solar panel through a wire to charge the storage battery with the solar panel, and the other pole is connected to the inverter through a wire and is placed on the storage rack.

[0012] Compared with the prior art, a solar passive refrigeration device using solid-liquid phase change in an embodiment of the present application is composed of four major modules: a PCM cold storage station, a power generation-refrigeration integrated board, a liquid-phase heat exchange pipeline, and an integrated circuit control system, and all structures are convenient for disassembly and assembly. When the device is running, only need to connect the inverter to the storage battery and turn on the inverter switch, and the device can run. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings described herein are used to provide a further understanding of the present application, and constitute a component part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation of the present application. Some specific embodiments of the present application will be described in detail hereinafter with reference to the drawings in an exemplary rather than restrictive manner. The same reference numerals in the drawings denote the same or similar components or component parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0014] Figure 1 is the overall structural schematic diagram of the present invention;

[0015] Figure 2 is the schematic diagram of the liquid-phase heat exchange pipeline in the present invention;

[0016] Figure 3 is the schematic diagram of the power generation-refrigeration integrated board in the present invention;

[0017] Reference numerals in the drawings:

[0018] 1, square iron frame; 2, PCM cold storage station; 3, heat transfer spiral copper pipe; 4, water pump; 5, power generation-refrigeration integrated board; 6, multi-branch copper pipeline; 7, phase change material; 8, solar panel; 9, radiation cooling film; 10, driven gear; 11, driving gear; 12, stepping motor; 13, bolt group; 14, flexible pipe; 15, hinge; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0020] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0021] In the description of this application, it should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0022] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality" means two or more unless otherwise specifically defined.

[0023] The solution of this application will be described in detail below by taking an in-situ surface radiation measurement device in the following embodiments of this application as an example, but this embodiment does not limit the scope of protection of this application.

[0024] Embodiment

[0025] Such as Figures 1 to 3As shown in the figure, an embodiment of the present application provides a solar passive refrigeration device using solid-liquid phase change, which includes a square iron frame (1). A PCM cold storage station (2) is installed at the lower part of the square iron frame (1). The hinge (15) on the side of the cold storage station (2) enables it to be turned up, facilitating the installation of the heat transfer spiral copper tube (3) into the interior and fixing it through the side through hole. A water pump (4) is installed on the lower left side of the square iron frame (1). A power generation-refrigeration integrated board (5) is installed above the cold storage station (2), and the power generation-refrigeration integrated board (5) has multi-branch copper pipelines (6) inside. The flexible tube (14) connects the multi-branch copper pipelines (6), the water pump (4), and the heat transfer spiral copper tube (3) in sequence.

[0026] As Figure 2 shown, the phase change material (7) wraps the heat transfer spiral copper tube (3). The left side of the heat transfer spiral copper tube (3) is connected to the left side of the upper multi-branch copper pipeline (6) through a three-way joint using a flexible tube (14). The right side of the multi-branch copper pipeline (6) is connected to the water pump (4) through a flexible tube (14) and a three-way joint. The outlet of the water pump (4) is connected to the right outlet of the multi-branch copper pipeline (6).

[0027] As Figure 3 shown, a solar panel (8) is installed on the front of the power generation-refrigeration integrated board (5). A radiative cooling film (9) is attached to the back of the power generation-refrigeration integrated board (6). A driven wheel (11) is sleeved on the left side of the multi-branch copper pipeline (6). The driving wheel (10) and the driven wheel (11) are meshed, and the driving wheel (10) is sleeved on the shaft of the stepping motor (12). After the multi-branch copper pipeline (6) is installed in the power generation-refrigeration integrated board (5), the power generation-refrigeration integrated board (5) is joined by screws and bolts (13), and the screws and bolts (13) are symmetrically arranged on both sides of the power generation-refrigeration integrated board (5).

[0028] Working principle:

[0029] During the day when there is sufficient sunlight, the solar panel (8) efficiently converts the absorbed solar energy into electrical energy by means of the photovoltaic effect, providing the power source for the operation of the entire device. The generated electrical energy preferentially powers the stepper motor (12). As the core transmission component, the precise stepping control characteristics of the stepper motor (12) ensure the stability of the rotation angle and speed. When the stepper motor (12) is driven by the received electrical energy, it drives the driving wheel (10) to rotate at a set frequency and direction. The driving wheel (10) meshes tightly with the driven wheel (11), and through the gear transmission method, the power is stably transmitted, thereby driving the power generation - refrigeration integrated plate (5) to rotate around the left and right round holes. By dynamically adjusting the angle of the power generation - refrigeration integrated plate (5), the radiation cooling film (9) on its back can always be in the optimal heat dissipation angle, making full use of the radiation characteristics in the 8 - 13μm band of the atmospheric window to conduct efficient thermal radiation exchange with the external environment, quickly dissipating the excess heat generated inside the device during operation and maintaining the thermal balance of the device.

[0030] At the same time, the water pump (4) also starts to work under the drive of electrical energy. The flow rate and head of the water pump (4) are precisely designed to ensure that the liquid flow stably flows in the circulation pipeline composed of the heat transfer spiral copper tube (3), the flexible tube (14), and the multi - branch copper pipeline (6) at an appropriate speed and pressure. The liquid flow flows along the circulation pipeline. When passing through the heat transfer spiral copper tube (3) inside the PCM cold storage station (2), the phase change material inside the PCM cold storage station (2) will undergo solid - liquid phase change. During the phase change process, the phase change material (7) will absorb a large amount of cold energy and store it. The cooled liquid flows into the multi - branch copper pipeline (6) through the flexible tube (14) and the three - way joint. The multi - branch copper pipeline (6) adopts a special flow - splitting design, which can evenly distribute the low - temperature liquid flow and flow through each area inside the power generation - refrigeration integrated plate (5). When the low - temperature liquid flow flows in the multi - branch copper pipeline (6), it further removes the heat generated by the power generation of the solar panel (8) and the heat exchange of the radiation cooling film (9) and other processes of the power generation - refrigeration integrated plate (5) through heat conduction and convection, thereby achieving the refrigeration effect on the surrounding environment of the device. The liquid that has been heated through heat exchange returns to the heat transfer spiral copper tube (3) of the PCM cold storage station (2) again under the suction of the water pump (4), overcoming the resistance of the circulation pipeline, and undergoes the next round of cooling cycle, so as to continuously achieve the refrigeration function.

[0031] At night, the solar panel (8) stops generating electricity. Since the phase change material (7) absorbs heat and undergoes a phase change during the day, a large amount of latent heat is stored. As the ambient temperature gradually decreases at night, the phase change material (7) begins to transform from a liquid state to a solid state. During this solidification process, the latent heat stored during the day is gradually released. The released latent heat can continue to provide cold energy for the circulating liquid, enabling the circulating liquid to remain at a relatively low temperature and continuously remove the heat from the power generation - refrigeration integrated plate (5) and the surrounding environment. Although there is no solar power supply at night, in the design, the device can use a battery to provide limited but sufficient electrical energy for the water pump (4) to ensure the flow of the circulating liquid, thereby ensuring that the refrigeration device can continue to operate at night and achieve passive refrigeration effect for 24 hours a day without interruption.

[0032] In addition, the square iron frame (1) in the device not only plays a role in supporting and fixing each component, but also its structural design fully considers mechanical balance and stability to ensure that the entire device can still operate stably under the conditions of the rotation of the power generation - refrigeration integrated plate (5) and the vibration generated by the operation of the water pump (4). The hinge (15) on the side of the cold storage station (2) enables the cold storage station (2) to be turned up. This design facilitates the inspection, maintenance, and replacement of the internal phase change material (7) and the heat transfer spiral copper tube (3) by the staff, improving the maintainability and service life of the device. Screws and bolts (13) are symmetrically arranged on both sides of the power generation - refrigeration integrated plate (5). This symmetric fastening method can ensure that the integrated plate is evenly stressed during rotation, avoiding deformation and damage caused by uneven stress, and further ensuring the reliable operation of the device.

[0033] Usage method:

[0034] First step, it is necessary to select an open area where sunlight can shine directly for a long time without being blocked by tall buildings, trees, etc. The solar panel (8) relies on sufficient sunlight to generate electricity efficiently, providing the electrical energy required for the operation of the entire refrigeration device. At the same time, the site should have good ventilation to ensure that the air around the radiative cooling film (9) can flow quickly, enhancing its heat exchange efficiency with the external environment and enabling heat to be dissipated more smoothly into the atmosphere. In addition, the ground should be solid and flat to ensure that the square iron frame (1) will not tilt or shake after being placed, laying a foundation for the stable installation of subsequent components.

[0035] Second step, check each component of the device. For the square iron frame (1), check whether its frame structure is firm and whether there are any situations affecting stability such as deformation or cracking; for the PCM cold storage station (2), check whether its outer shell is intact and whether the hinge (15) can rotate flexibly to ensure that the side of the PCM cold storage station (2) can be turned up smoothly for subsequent operation of internal components; for the heat transfer spiral copper tube (3), check whether there are any damages or depressions on the tube wall to ensure that there is no liquid leakage during the flow of the circulating liquid; for the water pump (4), check whether there is any damage on the appearance and whether the motor part can rotate normally; for the power generation - refrigeration integrated board (5), check whether there are any stains or cracks on the surface of the solar panel (8), whether there are any signs of peeling or damage to the radiative cooling film (9), and whether the overall structure of the integrated board is stable; for the multi - branch copper pipeline (6), check whether the pipeline is unobstructed and whether there is any deformation at the interface; for the driven wheel (11) and the driving wheel (10), check whether the teeth are complete and whether there is excessive wear; for the stepper motor (12), check whether the motor shaft can rotate smoothly and whether there is any damage to the motor housing; for the screws and bolts (13), check whether there are any problems such as stripped threads or defects; for the flexible tube (14), check whether there are any cracks or aging; for the phase change material (7), check whether its state is normal and whether there are any signs of deterioration.

[0036] Step 3: Assemble the components of the square iron frame (1) according to the design requirements. During the assembly process, ensure that all connection parts fit tightly, and use a wrench to tighten the connection screws. If it is found that the iron frame is not level, shims can be added at the corresponding positions at the bottom of the iron frame for adjustment until the iron frame is in a level and stable state. Install the PCM cold storage station (2) at the lower left position of the square iron frame (1), ensuring that the connection parts with the iron frame are accurately aligned. Open the side of the PCM cold storage station (2), and evenly wrap the phase change material (7) around the heat transfer spiral copper tube (3). Pay attention to the tightness and uniformity of the wrapping to ensure that the phase change material can be in full contact with the copper tube and improve the heat exchange efficiency. Then install the heat transfer spiral copper tube (3) inside the cold storage station (2) and fix it through the through holes on the side to ensure that the copper tube is stable in the cold storage station and will not shake. Determine the installation position of the water pump (4) at the lower right of the square iron frame (1). This position should not only facilitate the subsequent connection of the flexible tube (14) but also consider the maintenance convenience of the water pump, leaving enough space for the maintenance and component replacement of the water pump. Install and fix the water pump (4) at the selected position to ensure that it is firmly installed and will not shake or displace during operation. Install the power generation - refrigeration integrated board (5) above the PCM cold storage station (2), and accurately insert the multi-branch copper pipe (6) into the through holes on both sides of the power generation - refrigeration integrated board (5) so that the power generation - refrigeration integrated board (5) can rotate 360 degrees around the left and right round holes. Use symmetrically arranged screws and bolts (13) to combine the power generation - refrigeration integrated board (5). When tightening the screws and bolts, ensure that the power generation - refrigeration integrated board (5) is firmly connected and evenly stressed.

[0037] Step 4: Connect the pipelines with a three-way joint and the flexible tube (14). First, connect the left side of the heat transfer spiral copper tube (3) to the flexible tube (14) through a three-way joint. When connecting, ensure that the interface fits tightly. Sealing tapes and other auxiliary materials can be used to enhance the sealing performance and prevent liquid leakage. Then, connect the outlet of the water pump (4) to the left side of the multi-branch copper pipe (6) through the flexible tube (14), and also ensure the sealing and firmness of the connection. Finally, use the flexible tube (14) and the three-way joint to connect the right side of the heat transfer spiral copper tube (3) and the left and right sides of the multi-branch copper pipe (6) to form a complete circulating pipeline system. After the connection is completed, carefully check each connection part to ensure that there are no liquid leakage points. Slip the driven wheel (11) onto the left side of the multi-branch copper pipe (6), ensuring that the connection between the driven wheel (11) and the multi-branch copper pipe (6) is tight and concentric. Then, determine the positions of the driving wheel (10) and the driven wheel (11) to ensure that the teeth can transfer power well without jamming or interference. Finally, slip the driving wheel (10) onto the shaft of the stepping motor (12) to ensure that the connection between the driving wheel and the stepping motor shaft is firm and will not slip when the motor rotates.

[0038] Step 5, during the daytime when sunlight is sufficient, the solar panel (8) starts to absorb solar energy, converts it into electrical energy through the photovoltaic effect, and turns on the inverter switch. The solar panel (8) charges the battery. On the one hand, the generated electrical energy powers the stepper motor (12), causing it to drive the driving wheel (10) to rotate, thereby driving the power generation-refrigeration integrated plate (5) to rotate and adjusting the angle of the radiative cooling film (9). On the other hand, it powers the water pump (4) to push the circulating liquid to flow in the pipeline system to achieve the refrigeration cycle. During this period, the power generation situation of the solar panel (8) can be detected in real time through the human-machine interaction system, and the steering of the stepper motor (12) can be adjusted accordingly to ensure the highest power generation efficiency of the solar panel (8). Since the battery has been charged during the day, the battery can be used to power the device when needed at night, ensuring that the device can operate throughout the day.

Claims

1. A solid-liquid phase change passive refrigeration device, comprising a square iron frame (1), characterized in that: The square iron frame (1) serves as the support frame of the entire device, and a PCM cold storage station (2) is installed at its lower part. A rotatable structure is formed on the side of the PCM cold storage station (2) through a hinge (15). After the hinge (15) is turned upwards, the heat transfer spiral copper tube (3) can be smoothly inserted into its interior and fixed by means of the through holes on the side of the PCM cold storage station (2) to ensure stability during the operation of the device. A water pump (4) is installed on the lower left side of the square iron frame (1), and this water pump (4) is responsible for driving the flow of the circulating medium. The power generation - refrigeration integrated board (5) is located directly above the PCM cold storage station (2), and multiple - branch copper pipelines (6) are integrated inside the power generation - refrigeration integrated board (5). Both ends of the multiple - branch copper pipeline (6) are inserted into the holes pre - opened on the left and right sides of the power generation - refrigeration integrated board (5). The flexible pipe (14) connects the multiple - branch copper pipeline (6), the water pump (4), and the heat transfer spiral copper tube (3) in sequence.

2. The passive solid-liquid phase change refrigeration device described in claim 1, characterized in that: The phase - change material (7) tightly wraps around the outside of the heat transfer spiral copper tube (3) to form an efficient heat - exchange area. When the phase - change material (7) undergoes solid - liquid phase change, it can absorb or release a large amount of latent heat, thereby realizing the refrigeration or cold - storage function. The left side of the multiple - branch copper pipeline (6) is connected to the water pump (4) through a flexible pipe (14) and a three - way joint, and the outlet of the water pump (4) is connected to the right - hand outlet of the multiple - branch copper pipeline (6). The right side of the heat transfer spiral copper tube (3) is also connected to the water pipe (14) through a three - way joint and then connected to the left - hand port of the upper - side multiple - branch copper pipeline (6), thus forming a complete closed - loop circulation circuit.

3. A solid-liquid phase change passive refrigeration device according to claim 1, characterized in that: After the multiple - branch copper pipeline (6) is installed inside the power generation - refrigeration integrated board (5), it is tightly connected through bolt groups (13) symmetrically arranged on both sides of the power generation - refrigeration integrated board (5). A solar panel (8) is installed on the front of the power generation - refrigeration integrated board (5) to enable the passive operation of the electrical components in the device. A radiative cooling film (9) is attached to the back of the power generation - refrigeration integrated board (5). A driven wheel (11) is sleeved on the left side of the multiple - branch copper pipeline (6), and a driving wheel (10) is sleeved on the shaft of the stepping motor (12). The power generation - refrigeration integrated board (5) is flipped by the meshing of the driving wheel (10) and the driven wheel (11).

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