Solar heat exchange device

Abstract

The invention relates to the field of solar heating, in particular to a solar heat exchange device which comprises a shell and a bottom plate, the shell and the bottom plate form a closed cavity, a heat absorption layer is arranged on the outer surface of the shell, a heat conduction pipe and a phase change energy storage material are arranged in the cavity, and the inlet end and the outlet end of the heat conduction pipe extend out of the side wall of the shell. The phase change energy storage material is arranged around the heat conduction pipe and fills the cavity, a thermal expansion layer is arranged on the inner surface of the bottom plate, and the thermal expansion layer is arranged at the bottom of the cavity. In the invention, the thermal expansion layer is located below the phase change energy storage material. When the temperature rises, the volume of the thermal expansion layer is increased and pushes the phase change material upwards, so that the liquid level of the phase change material is raised, and the phase change material can be in close contact with the top heat absorption layer continuously even in a liquid state. The problems of gaps and thermal resistance caused by volume shrinkage of the phase change material are effectively avoided, it is guaranteed that heat can be efficiently transmitted to the energy storage medium, and therefore the heat transfer efficiency of the solar heat exchange device is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solar heating, in particular, to a solar heat exchange device. BACKGROUND

[0002] The heat exchange device is an energy utilization unit for realizing heat transfer and storage. Its basic principle is to absorb external energy and convert it into heat energy, then store it through heat transfer medium or energy storage material, and finally release it for application when needed. With the development of renewable energy, solar heat exchange devices have been widely researched and applied. They use the heat-absorbing layer on the surface of the shell to convert solar radiation energy into heat and transfer it to the internal energy storage medium. They can be used in fields such as domestic hot water heating, building heating, industrial hot water and steam supply, agricultural drying, and greenhouse heating, and have the advantages of energy saving and environmental protection.

[0003] Among many energy storage media, phase change materials are widely used in solar heat exchange devices because they can absorb or release a large amount of latent heat during the phase change process. When the external temperature rises to the phase change point, the phase change energy storage material can directly contact the heat-absorbing shell in a solid state, and then change from a solid state to a liquid state. During this process, although the material can store a large amount of heat energy, its physical volume usually changes significantly, for example, the liquid volume of paraffin-based, fatty acid-based, or inorganic salt hydrate-based phase change materials is smaller than the solid volume during solid-liquid transition. Due to the effect of gravity, the liquid phase change material will gradually sink, resulting in a gap between it and the heat-absorbing layer located at the top of the cavity. This significantly increases the contact thermal resistance, weakening the efficiency of heat transfer from the heat-absorbing layer to the phase change material, causing the phase change energy storage material to be unable to fully absorb heat energy, and reducing the heat storage and release performance. At the same time, since the phase change process occurs repeatedly in multiple thermal cycles, it accumulates and affects the heat exchange efficiency of the heat exchange device.

[0004] In summary, the existing solar heat exchange device has low heat transfer efficiency. SUMMARY

[0005] The present application aims to provide a solar heat exchange device to solve the problem of low heat transfer efficiency of the existing solar heat exchange device.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: The present application provides a solar heat exchange device, which comprises an outer shell, a bottom plate, and a heat-absorbing layer. The outer shell and the bottom plate form a closed cavity, the outer surface of the outer shell is provided with a heat-absorbing layer, the cavity is provided with a heat-conducting pipe and a phase change energy storage material, the inlet end and the outlet end of the heat-conducting pipe extend from the side wall of the outer shell, the phase change energy storage material is arranged around the heat-conducting pipe and fills the cavity, and the inner surface of the bottom plate is provided with a thermal expansion layer, which is arranged at the bottom of the cavity.

[0007] The heat expansion layer is arranged on the inner surface of the bottom plate of the chamber, and is at the bottom of the phase change energy storage material. When the temperature rises, the heat expansion layer expands under the heat, the volume increases and pushes the phase change energy storage material in the chamber upward, so that the overall liquid level of the liquefied shrinkage phase change energy storage material rises. Ensure that the phase change energy storage material can still maintain sufficient contact with the heat absorption layer at the top of the chamber in the liquid state, effectively reduce the interface contact thermal resistance, and enhance the heat transfer path. Therefore, the technical scheme of the application solves the gap problem caused by the volume shrinkage of the existing solar heat exchange device during the phase change energy storage process by arranging the heat expansion layer at the bottom of the chamber, greatly improves the heat transfer efficiency, improves the energy storage utilization rate and the overall performance of the system.

[0008] In use, the bottom plate faces downward, and the top wall of the shell faces upward. The top wall and the side wall are provided with heat absorption layers on the outer surfaces. Under the irradiation of sunlight, the heat absorption layers can convert solar energy into heat energy and transfer the heat energy to the inside of the chamber through the shell. The chamber is filled with phase change energy storage material. After absorbing heat, the material gradually reaches its phase change temperature, changes from solid to liquid and stores a large amount of latent heat, thereby realizing efficient storage of solar energy. At the same time, the chamber is arranged with a heat conducting pipe, and the inlet end and the outlet end of the heat conducting pipe are respectively connected with external pipelines. When a lower-temperature material to be heated flows through the heat conducting pipe, the heat conducting pipe wall and the phase change energy storage material form a heat exchange interface. The phase change energy storage material releases the heat absorbed and stored during the phase change, and transfers the heat to the working fluid flowing inside through the heat conducting pipe, thereby realizing heating of the gas or liquid. In this way, the heat exchange device can store solar heat during the day when the sun shines, and release heat energy to heat external fluid when needed, realizing space-time transfer of energy and improving solar energy utilization efficiency.

[0009] Further, the heat expansion layer is a gas bag filled with expansion gas. The application uses a gas-filled gas bag as the bottom heat expansion layer. The heat expansion of the gas is high, and the volume or internal pressure can increase rapidly with the increase of temperature, thereby driving the gas bag to deform and push the phase change energy storage material upward. Compared with solid or liquid, the gas expansion response is sensitive, the pressure distribution is uniform, and the number of cycles is large, which is more conducive to continuously providing flexible compensation force during the liquefaction and shrinkage of the material, so that the phase change energy storage material maintains close contact with the heat absorption layer of the upper wall.

[0010] Further, the air bag has a thick edge in the middle and a concave upper surface. The air bag has a concave upper surface, which makes the air bag preferentially lift the periphery when it expands under heat. The shape refers to the shape of the air bag when the pressure on the inside and outside of the air bag is equal. In this application, the corner area at the intersection of the top wall and the side wall is in close contact with two or even three heat-absorbing walls. Due to the superposition of two-dimensional or three-dimensional heat conduction in this area, the local equivalent heat transfer flux is significantly higher than that in the plane area; at the same time, this part has a relatively larger outer surface area, which is exposed on multiple sides in natural convection and radiation heat transfer, and has a higher equivalent heat transfer coefficient, so it can absorb and transfer heat faster. At the same time, the material volume of the corner area is relatively small, and the heat capacity is low, so the temperature rises faster under the same heat input, so it is easier to reach the phase change temperature and melt at the beginning of heating. The melting and volume shrinkage of the phase change energy storage material at the corner position will preferentially form gaps between the upper wall or the side wall, so that the problem of poor thermal contact first occurs in the peripheral corner area. The intersection of the top wall and the side wall not only bears multi-directional heat conduction, but also is located at the outer edge of multi-face heat dissipation, and the geometric size effect is superimposed, which finally leads to the area being more prone to melting shrinkage and gap problems at the beginning of temperature rise. The bottom surface of the air bag is concave, so when the edge area just melts to form a gap, the air bag expands to lift the periphery first, thereby compensating for the insufficient contact of the edge and effectively avoiding the increase in thermal resistance. As the temperature continues to rise, the air bag inflates as a whole, ensuring that the entire upper surface uniformly pushes up the liquid phase change material. The concave air bag realizes preferential compensation and can also realize overall pushing in the subsequent stage, improving the heat conversion efficiency of the device.

[0011] Further, heat-conducting fins are arranged around the heat-conducting pipe, and the heat-conducting fins include a first fin group arranged between the heat-conducting pipe and the upper surface of the shell and a second fin group arranged between the heat-conducting pipe and the bottom plate. The first fin group and the second fin group are integrally coupled with the heat-conducting pipe, and the two groups of fins are arranged in a three-dimensional heat-conducting grid. The effective area of heat transfer is greatly expanded, so that heat can be quickly and uniformly conducted in both the heat absorption and heat release processes. In the heat absorption stage, the heat absorption layer on the upper surface quickly transfers the heat converted by solar energy to the heat-conducting pipe and the phase change energy storage material around the heat-conducting pipe through the first fin group, and the second fin group at the bottom further disperses and uniformly transfers the heat, so that the phase change energy storage material in the entire cavity can synchronously participate in heat absorption and quickly enter the phase change state. In the heat release stage, the heat released by the phase change energy storage material away from the heat-conducting pipe can be quickly transferred back to the heat-conducting pipe through the heat-conducting grid formed by the upper and lower fin groups, so that the fluid in the pipe is continuously and efficiently heated. That is, the first fin group and the second fin group form a multi-directional heat conduction network, effectively reducing the temperature difference gradient in the cavity, avoiding local heat transfer lag, and significantly improving the heat conversion efficiency and energy utilization rate.

[0012] Further, the distance between adjacent fins of the first fin group is smaller than the distance between adjacent fins of the second fin group. The smaller distance between adjacent fins of the first fin group increases the effective heat transfer area, so that the solar heat absorbed by the upper surface of the shell can be quickly transferred to the phase change energy storage material, thereby improving the overall heat exchange efficiency of the heat absorption stage and making the phase change material enter the phase change process faster. The second fin group is located between the bottom plate and the heat conducting pipe, and the distance between adjacent fins is relatively large, so as to avoid excessive heat absorption being transferred to the bottom plate area, thereby reducing heat loss in the direction of the bottom plate. At the same time, the larger distance can form a heat conduction channel to ensure that the heat of the bottom phase change material in the heat release stage can be transferred to the heat conducting pipe, and also avoids the thermal bridge effect. The purpose of rapid heat absorption at the upper part and reduced heat dissipation at the lower part is achieved, and the overall heat transfer efficiency is improved.

[0013] Further, one end of the first fin group is connected to the outer wall of the heat conducting pipe, and the other end is connected to the top wall of the shell. One end of the first fin group is connected to the outer wall of the heat conducting pipe, and the other end is directly connected to the top wall of the shell, so that the solar heat obtained by the heat absorption layer of the shell can be quickly transferred along the fin to the phase change energy storage material around the heat conducting pipe, forming an efficient heat absorption channel and improving the energy input efficiency.

[0014] Further, one end of the second fin group is connected to the outer wall of the heat conducting pipe, and the other end is not in contact with the thermal expansion layer. One end of the second fin group is also connected to the outer wall of the heat conducting pipe, but the other end is not in contact with the thermal expansion layer at the bottom, which avoids the direct transfer of a large amount of heat from the fin to the bottom plate area, thereby reducing heat loss to the outside, and also leaving sufficient space for the expansion of the air bag to ensure that it can effectively push when the phase change material is liquefied and shrinks.

[0015] Further, the fin near the one end of the first fin group near the shell is provided with a through hole. The through hole is provided on the fin near the one end of the first fin group near the shell. Not only does it have a weight-reducing effect on the structure, but it also improves the flow characteristics of the liquid phase change energy storage material between the fins. When the temperature rises and the bottom thermal expansion layer expands and pushes, if the end of the fin is completely closed, the liquid phase change material is easily blocked in some areas, causing the liquid level in some areas to fail to rise synchronously, thereby leaving a gap between the top plate and the liquid, increasing the interfacial thermal resistance, and weakening heat transfer. After the through hole is set, the liquid can flow freely between adjacent cavities through the pores, ensuring the integrity and uniformity of the liquid surface, so that the phase change energy storage material can quickly adhere to the top wall of the shell. In addition, the through hole also helps to form a natural convection channel inside the liquid in the heat release stage, so that the released latent heat can be more efficiently conducted to the heat conducting pipe, improving the heat exchange uniformity.

[0016] Furthermore, the inner wall of the heat pipe is equipped with baffles. When the fluid to be heated flows through the heat pipe, it impacts the baffles, altering its flow direction and velocity, creating strong eddies and turbulence. Compared to laminar flow, turbulence significantly increases the convective heat transfer coefficient between the fluid and the pipe wall, allowing the fluid inside the pipe to absorb heat from the pipe wall more fully. Simultaneously, the continuous impact of the fluid on the baffles causes slight vibrations in the heat pipe, which are transmitted to the heat-conducting fins outside the pipe, causing them to vibrate slightly. During this vibration, the fins break down the local thermal boundary layer on the surface of the phase change energy storage material, promoting the flow and agitation of the liquid phase change material, thereby improving the heat transfer uniformity inside the cavity. In other words, the baffles improve the heat transfer efficiency inside the pipe by changing the flow state, and indirectly enhance the thermal conductivity between the external fins and the phase change energy storage material by introducing mechanical vibration. This improves the overall thermal conversion efficiency of the solar heat exchange device.

[0017] Furthermore, the phase change energy storage material is one of the following: paraffin-based, fatty acid-based, graphite-containing composite PCM, or inorganic salt hydrate composite PCM.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This application features a thermal expansion layer on the inner surface of the chamber's bottom plate, capable of volume change with temperature variations, located below the phase change energy storage material. During operation, external sunlight causes the heat-absorbing layer to convert solar energy into heat and transfer it into the chamber. As the phase change energy storage material's temperature rises, it undergoes a phase change from solid to liquid, accompanied by some volume contraction. This results in a gap between the upper surface and the heat-absorbing layer on the chamber's top wall, increasing interfacial thermal resistance and limiting further heat transfer. This application utilizes the bottom thermal expansion layer as a compensation unit. As the temperature rises, this layer expands, increasing its volume and pushing the phase change energy storage material upwards, raising its liquid level. This ensures that even when the material is in a liquid state, it maintains close contact with the top heat-absorbing layer, guaranteeing efficient heat transfer into the energy storage medium. This avoids the reduced heat transfer efficiency caused by the volume contraction of the phase change material, thus improving the heat transfer efficiency of the solar energy exchange device. Attached Figure Description

[0019] Figure 1 A schematic diagram of a solar heat exchange device provided by the present invention; Figure 2 A top view of a solar heat exchange device provided by the present invention; Figure 3 A schematic diagram of fins in a solar heat exchanger provided by the present invention; Figure 4 This is a schematic diagram of the grooves on the surface of the fins in a solar heat exchanger provided by the present invention; Figure 5A schematic diagram of the through hole at the upper end of the fins in a solar heat exchanger provided by the present invention; Figure 6 This is a schematic diagram of a heat pipe with a baffle plate installed inside, which is provided by the present invention in a solar heat exchange device.

[0020] Icons: 1-Outer shell; 2-Base plate; 3-Heat absorption layer; 4-Phase change energy storage material; 5-Heat pipe; 6-Thermal expansion layer; 7-Fins; 8-Break plate. Detailed Implementation

[0021] To make the implementation process of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings.

[0022] This application provides a solar heat exchange device, such as... Figure 1 As shown, the heat exchange device includes a shell 1 and a base plate 2, which together form a closed chamber. The shell 1 and the base plate 2 are fixedly connected, which can be a threaded connection, an adhesive connection, or other methods. A heat-absorbing layer 3 is provided on the outer surface of the shell 1. The shell 1 is made of metal, such as aluminum, copper, gold, or silver, preferably aluminum. Aluminum has a thermal conductivity of 237 W / mK, is low in cost, and has relatively stable properties, making it easier to transfer heat from the external heat-absorbing layer 3 to the interior of the chamber. The heat-absorbing layer 3 is made of materials such as black chromium, black nickel, or titanium oxynitride, with a thickness of 500 nm-1000 μm. It has good photothermal performance, converting solar heat into heat, which is then transferred to the interior of the chamber through the shell 1.

[0023] The chamber contains heat-conducting pipes 5 and phase change energy storage material 4. The phase change energy storage material 4 is one of the following: paraffin-based, fatty acid-based, graphite-containing composite PCM, or inorganic salt hydrate composite PCM; its phase change temperature is 40-80℃, and its latent heat is 120-250 KJ / kg. During the phase change process, these materials can absorb or release a large amount of latent heat while maintaining a relatively stable temperature, thus achieving high-density storage and release of thermal energy. The latent heat absorbed during solidification and melting serves as energy storage; the graphite-containing composite material also improves thermal conductivity, solving the problem of slow heat transfer in traditional PCMs. The inlet and outlet ends of the heat-conducting pipes 5 extend from the side wall of the outer shell 1. The heat-conducting pipes 5 are arranged in an S-shape inside the outer shell 1, and both ends are fixed to the inner wall of the outer shell 1 by fixed brackets to improve the stability of the device and prevent the heat-conducting pipes 5 from shifting. The phase change energy storage material 4 is placed around the heat-conducting pipes 5 and fills the entire chamber. The base plate 2 is made of thermal insulation material, specifically glass wool, asbestos, or polyurethane foam, with a thermal conductivity of less than 0.045 W / mK. On the one hand, it provides good thermal insulation, preventing internal heat from being conducted out through the base plate 2 and causing heat loss. On the other hand, it supports the internal structure and provides a sealed space to prevent the liquid phase change energy storage material 4 from flowing out.

[0024] A thermal expansion layer 6 is provided on the inner surface of the base plate 2, and the thermal expansion layer 6 is located at the bottom of the chamber. Preferably, the thermal expansion layer 6 is an airbag structure, and the airbag is filled with one of argon, nitrogen, air, and carbon dioxide. More preferably, the filling gas is argon. Argon is an inert gas with stable chemical properties, does not react with the airbag material, and has good durability. Argon has poor thermal conductivity, which can reduce heat transfer from the airbag to the base plate 2, thereby reducing heat loss. At the same time, argon has a large coefficient of thermal expansion, and its volume changes significantly when the temperature rises, which can provide sufficient expansion capacity for the airbag, ensuring that it can reliably push the phase change energy storage material 4 upward and maintain its close contact with the top heat-absorbing layer 3, thereby improving heat exchange efficiency and energy storage performance. The airbag body is made of a high-temperature resistant and fatigue-resistant elastic material, such as silicone rubber, fluororubber, polytetrafluoroethylene, or polyimide, to ensure good sealing and mechanical strength under repeated thermal cycling. The airbag membrane thickness is 0.05-1.5mm to balance flexibility and pressure resistance. The airbag and base plate 2 can be sealed and bonded using high-temperature resistant adhesives such as silicone adhesive or epoxy resin, or fixed using mechanical slots or bolts to ensure a firm connection. Furthermore, wear-resistant gaskets are placed between the airbag and base plate 2 to prevent damage to the airbag due to mechanical friction. It should be noted that when the phase change energy storage material 4 does not need to be pushed upwards, the pressure inside and outside the airbag is equal; that is, the internal pressure is equal to the external pressure exerted by the weight of the phase change energy storage material 4 on the airbag. The airbag can also be connected to an external air pump to further increase the pressure when the airbag is insufficient, achieving better pushing.

[0025] Furthermore, the airbag is thin in the middle and thick at the edges, and its upper surface has a continuous concave shape, such as... Figure 2 As shown. The concave surface preferentially lifts the surrounding edge areas when the gas expands due to heat, thereby compensating for the gaps caused by the early melting of the phase change energy storage material 4 at the junction of the top and side walls due to the edge effect. Compared with the stepped structure, the concave surface has the advantage of a continuous curved transition, avoiding stress concentration and local wrinkles, and improving the reliability of the airbag in multiple thermal cycles. The radius of curvature of the concave surface is 0.3-1.0 times the width of the cavity. If it is too small, it will lead to excessive local stress and easy damage; if it is too large, the lifting effect will be insignificant. Preferably, the thickness of the airbag body is different, with a smaller thickness in the middle area and a larger thickness in the edge area. Specifically, the thickness in the middle area is 0.05-0.5 mm, and the thickness in the edge area is 0.8-1.5 mm; the edge has better pressure bearing capacity.

[0026] Furthermore, such as Figure 3As shown, fins 7 are also arranged around the heat pipe 5. The fins 7 include a first fin group disposed between the heat pipe 5 and the upper surface of the outer shell 1, with one end connected to the outer wall of the heat pipe 5 and the other end connected to the top wall of the outer shell 1. A second fin group is disposed between the heat pipe 5 and the base plate 2, with one end connected to the outer wall of the heat pipe 5 and the other end not in contact with the thermal expansion layer 6. The fins 7 are made of a material with good thermal conductivity, such as aluminum, graphite, or silicon carbide. The thickness of the fins 7 is 0.2-1.5 mm. The spacing between adjacent fins 7 in the first fin group is smaller than the spacing between adjacent fins 7 in the second fin group. A third fin group is also provided, arranged horizontally, with one end fixedly connected to the side wall of the heat pipe 5 and the other end suspended as a free end. The horizontal fins 7 can quickly transfer heat from the surface of the heat pipe 5 to the lateral region of the phase change energy storage material 4, expanding the heat diffusion range and avoiding the phenomenon of high-temperature zones forming only near the pipe wall. At the same time, the design of the free end makes the fins elastic during the expansion or contraction of the phase change energy storage material 4, which is not prone to excessive stress concentration and can maintain good contact and heat conduction effects for a long time, thereby further improving the overall heat transfer efficiency and temperature distribution uniformity of the heat exchange device.

[0027] To improve heat transfer performance, vertical grooves are provided on the surface of fin 7, such as... Figure 4 As shown. In this way, on the one hand, the grooves increase the contact area between the fins 7 and the phase change energy storage material 4, making the heat distribution more uniform, while changing the local heat flow path, reducing thermal resistance, and increasing heat flux density; on the other hand, the protrusions between adjacent grooves act as reinforcing ribs, increasing the compressive strength of the fins 7, especially the pressure in the direction perpendicular to the fins 7. The overall rigidity and pressure-bearing capacity are enhanced, making it less prone to bending when the phase change energy storage material 4 undergoes solid-liquid volume changes, improving stability, and making the heat conduction path more stable; furthermore, when the phase change energy storage material 4 is in a liquid state, a density difference is generated in the cavity due to the temperature difference, with hot liquid tending to rise and cold liquid tending to sink. The parallel grooves provide a fixed flow channel for natural convection, allowing the liquid to undergo micro-circulation along the groove direction, thereby driving fluid movement in adjacent areas. Compared with completely smooth fins 7, fins 7 with parallel grooves not only expand the contact area but also form a regular temperature field distribution inside the cavity, allowing heat to quickly diffuse from high-temperature areas to low-temperature areas, avoiding local overheating or stagnation. This makes the overall temperature distribution of the phase change energy storage material 4 more uniform, and enables rapid heat exchange between the area around the heat pipe 5 and the far-end area, thereby improving heat transfer efficiency and energy storage utilization.

[0028] The semi-circular cross-sectional shape of the groove avoids stress concentration at sharp corners, resulting in a more uniform stress distribution. This reduces the likelihood of cracks or fatigue damage during repeated expansion and contraction cycles of the phase change energy storage material 4, improving the reliability of the fins 7. The continuous and smooth curvature allows for a gentle transition of heat flow lines as they pass through the groove, preventing heat accumulation or localized thermal resistance bottlenecks. Heat can diffuse evenly along the groove direction, avoiding overheating or stagnation in localized areas and improving heat transfer efficiency. Simultaneously, the smooth surface of the semi-circular groove bottom reduces frictional resistance as the liquid phase change energy storage material 4 flows within the groove, facilitating natural circulation or micro-convection during heating or cooling, enabling faster positional exchange within the material during heat exchange. Compared to sharp-corner grooves, the semi-circular groove has a smaller dead zone, maintaining a continuous and unobstructed flow path. This improves the uniformity of heat transfer and promotes overall temperature equalization within the cavity, enhancing the efficiency of the heat exchange device.

[0029] The depth of the groove is one-quarter to one-third of the thickness of the fin 7; this effectively increases the contact area with the phase change energy storage material 4, providing more heat transfer paths, without weakening the overall thermal conductivity of the fin 7, ensuring sufficient strength and thermal conductivity. Grooves are provided on both sides of the fin 7, forming symmetrical microchannels that allow the liquid phase change energy storage material 4 to generate micro-convection when heated or cooled, promoting uniform heat distribution within the cavity. In other words, the grooves make the fin 7 not only more stable in mechanical properties but also more efficient in thermal performance, thus significantly improving the heat transfer efficiency and energy storage utilization rate of the solar heat exchange device.

[0030] Furthermore, the fins 7 near the outer shell 1 of the first fin assembly are provided with through holes. The diameter of the through holes is 5-20mm, which ensures smooth liquid flow without reducing the structural strength of the fins 7. The spacing between adjacent holes is 10-30mm. The holes are funnel-shaped, wider at the outside and narrower at the inside. From a cross-sectional view, the surface aperture of the fin 7 is large, while the internal aperture of the fin 7 is small. Figure 5 As shown, large orifices facilitate fluid inflow, while small orifices facilitate directional outflow, reducing contact resistance during liquid entry and exit. This promotes fluid exchange and micro-convection, thereby facilitating sufficient liquid exchange between the fins 7, avoiding local voids caused by liquid level differences, and maintaining continuous contact between the liquid and the fin surface 7. Simultaneously, the enlarged edge of the flared orifice increases the contact area between the fin 7 and the phase change energy storage material 4, forming more local heat exchange interfaces. It also helps to disturb the fluid and disrupt the boundary layer, allowing heat to be transferred more evenly and rapidly to the interior of the phase change energy storage material 4. Furthermore, it disperses stress at the orifice edge, preventing crack propagation caused by stress concentration and improving the stability of the fin 7 during multiple thermal cycles. The liquid phase change energy storage material 4 can freely flow and exchange between the fins 7, ensuring a uniform overall liquid level rise, reducing contact thermal resistance caused by inconsistent local liquid levels, thereby improving heat transfer efficiency and system stability.

[0031] Furthermore, a baffle 8 is provided on the inner wall of the heat pipe 5. The baffle 8 is conical in shape, and one or more can be provided. The diameter of the cone tip is smaller near the central axis of the heat pipe 5, while the base size is larger near the pipe wall. Figure 6 As shown. In this design, the flow velocity is highest in the central region of the heat pipe 5. When the fluid impacts the small-diameter cone, it generates strong local disturbances and pulsating pressure, thus inducing a larger vibration amplitude and making the heat pipe 5 more susceptible to forced vibration. Near the pipe wall, the cross-section of the baffle 8 gradually thickens, increasing the contact stiffness and force transmission area with the pipe wall, facilitating the efficient transmission of vibration to the pipe wall of the heat pipe 5 and further to the external fins 7. Simultaneously, the cone shape promotes the formation of stable vortex shedding, continuously generating pulsed turbulence enhancement effects within the pipe, improving the heat transfer coefficient between the fluid and the pipe wall. When the fluid impacts the cone, it creates a velocity gradient and pressure difference upstream and downstream, further promoting turbulence and periodic boundary layer disruption. The cone shape also disperses stress, preventing fatigue fracture of the flat baffle element due to excessive impact force, thereby improving the durability and service life of the device. The pointed conical baffle 8 causes the external fins 7 of the heat pipe 5 to have a stronger vibration amplitude, effectively destroying the thermal boundary layer on the side of the phase change energy storage material 4, enhancing micro-convection and thermal coupling, and improving the overall heat transfer efficiency of the solar heat exchange device.

[0032] Furthermore, the baffle 8 is made of an elastic material, which can be a metallic elastic material, such as stainless steel sheet, spring steel, or titanium alloy; or a polymeric elastic material, such as polytetrafluoroethylene, polyimide, silicone rubber, or fluororubber. Under the impact of the fluid, the elastic material will generate micro-amplitude reciprocating vibrations, thereby periodically disturbing the fluid inside the pipe and exciting the vibration of the pipe wall and external fins 7 of the heat pipe 5, increasing the turbulence and thermal boundary layer disruption efficiency during heat exchange, and improving the heat transfer coefficient. Simultaneously, the elastic material can quickly recover its original shape after being impacted, possessing good fatigue resistance, making it suitable for long-term stable operation under multiple thermal cycles, and less prone to permanent deformation or damage.

[0033] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A solar heat exchange device, comprising a shell and a base plate, the shell and the base plate forming a closed chamber, a heat-absorbing layer being disposed on the outer surface of the shell, a heat-conducting pipe and a phase change energy storage material being disposed in the chamber, the inlet end and outlet end of the heat-conducting pipe extending from the side wall of the shell, the phase change energy storage material being disposed around the heat-conducting pipe and filling the chamber, characterized in that: A thermal expansion layer is provided on the inner surface of the base plate, and the thermal expansion layer is located at the bottom of the chamber.

2. The solar heat exchanger according to claim 1, characterized in that, The thermal expansion layer is an air bladder, which is filled with expanding gas.

3. The solar heat exchanger according to claim 2, characterized in that, The airbag is thin in the middle and thick at the edges, with a concave upper surface.

4. The solar heat exchanger according to claim 3, characterized in that, The heat-conducting pipe is also surrounded by heat-conducting fins, which include a first fin group disposed between the heat-conducting pipe and the upper surface of the outer shell, and a second fin group disposed between the heat-conducting pipe and the base plate.

5. The solar heat exchanger according to claim 4, characterized in that, The spacing between adjacent fins in the first fin group is smaller than the spacing between adjacent fins in the second fin group.

6. The solar heat exchanger according to claim 5, characterized in that, One end of the first fin assembly is connected to the outer wall of the heat pipe, and the other end is connected to the top wall of the outer shell.

7. The solar heat exchanger according to claim 6, characterized in that, The fins of the first fin group near the outer shell have through holes.

8. The solar heat exchanger according to claim 7, characterized in that, One end of the second fin assembly is connected to the outer wall of the heat pipe, and the other end is not in contact with the thermal expansion layer.

9. The solar heat exchanger according to claim 8, characterized in that, The inner wall of the heat pipe is provided with a baffle plate.

10. The solar heat exchanger according to claim 9, characterized in that, The phase change energy storage material is one of the following: paraffin-based, fatty acid-based, graphite-containing composite PCM, or inorganic salt hydrate composite PCM.

Images