Phase change material heat storage device and method for actively realizing contact melting

Abstract

The application discloses a phase change material heat storage device and a method for actively realizing contact melting, and belongs to the field of heat transfer intensification of phase change material heat storage devices. The heat storage device comprises a packaging mechanism, a heat storage module and a pneumatic driving module. The method comprises a heat absorption stage and a heat release stage. In the heat absorption stage, a telescopic rod drives a pressing plate to extrude solid phase change material, and a heat source supplies heat through a heat conduction surface. After melting, the telescopic rod continuously presses down, so that the solid phase keeps in close contact with the heat conduction surface and extrudes the liquid phase to the empty space in the cavity, so that the heat absorption is continuously carried out in the liquid phase film near the heat conduction surface. In the heat release stage, after complete melting, an air bag is unfolded to push the surrounding side pressing plates to extrude the liquid phase, so that the liquid phase is concentrated and solidified to release heat and be shaped. After complete solidification, the air bag is retracted to reset the side pressing plates, and a separation gap is formed between the wall surface and the solidified phase change material, so as to be prepared for the next cycle. The application realizes the active contact melting and solidification of the phase change material through pneumatic driving, and has high power density and recycling ability.

Description

Technical Field

[0001] This invention relates to the field of heat transfer enhancement in phase change material thermal storage devices, and particularly to a phase change material thermal storage device and a method for actively achieving contact melting. Background Technology

[0002] Phase change thermal energy storage (PCE) technology relies on the reversible phase change of PCE materials during heat absorption or release to store thermal energy. It plays a crucial role in addressing the intermittency and instability of renewable energy systems, mitigating the spatial and temporal mismatch between energy supply and demand, improving waste heat utilization, and regulating the operating temperature of electronic equipment. PCEs offer significant advantages such as high energy density, low heat loss, and environmental friendliness. However, PCEs generally suffer from inherently low thermal conductivity, making it difficult to achieve high power density to meet the high-efficiency thermal energy storage requirements of most applications, severely limiting the heat transfer performance of thermal energy storage systems. Currently, common improvement and enhancement methods are passive, including adding high thermal conductivity fillers such as fins, porous materials, nanoparticles, or liquid metals to improve the overall thermal conductivity of the material. While these methods optimize the internal heat conduction path of the material, they cannot fundamentally solve the key problem of the natural separation between the PCE material and the heat source interface after melting, leading to increased thermal resistance and making it difficult to achieve high power density throughout the thermal energy storage process. Furthermore, since the high thermal conductivity fillers themselves do not participate in the phase change thermal energy storage process, the system still faces a significant trade-off between pursuing high energy density and high power density.

[0003] Contact melting, as a unique heat transfer mode, can achieve both high power density and high energy density in thermal storage systems without altering the inherent properties of the phase change material (PCM). Its core lies in applying a continuous and constant external force to the PCM, extruding the liquid phase layer with low thermal conductivity. This effectively shortens the heat transfer distance between the phase interface and the heat source, mitigating the problem of continuous attenuation of the heat transfer rate during melting. Actively driven approaches hold promise for engineering applications of contact melting in PCM thermal storage systems. However, existing solutions mostly focus on a single melting stage. For example, they utilize elastic piston actuators composed of shape memory springs and bias springs to apply pressure to the solid PCM to bring it close to the heat source. These solutions do not yet consider integrated solutions suitable for the cyclic heat absorption and release processes of the thermal storage system, making it difficult to meet the application requirements of long-term operation or repeated charging and discharging. Therefore, there is an urgent need to develop an actively enhanced PCM thermal storage device that features stable pressure application, simple structure, adjustable pressure, and suitability for cyclic operation. Summary of the Invention

[0004] The purpose of this invention is to provide a phase change material thermal storage device and a method for actively achieving contact melting, which solves the problems in the prior art such as the dramatic increase in thermal resistance due to the distance between phase interfaces, the high thermal conductivity filler occupying the thermal storage space, and the inability of the active drive scheme to meet the requirements of cyclic reuse.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides a phase change material (PCM) thermal storage device, including an encapsulation mechanism. The encapsulation mechanism contains a thermal storage module and a pneumatic drive module. The thermal storage module includes a PCM filling cavity. A heat conduction surface is provided at the bottom of the encapsulation mechanism, and an external heat source is provided on the outside of the encapsulation mechanism. The pneumatic drive module includes a telescopic rod disposed on the top inner wall of the encapsulation mechanism. A pressure plate is provided at the working end of the telescopic rod. Side pressure plates are provided around the PCM filling cavity, and an airbag is provided on the side of the side pressure plate away from the PCM filling cavity. Both the telescopic rod and the airbag are connected to a pneumatic transmission system. The phase change material is disposed inside the phase change material filling cavity, the top surface of the phase change material abuts against the pressure plate, and the bottom surface of the phase change material abuts against the heat conduction surface; when the phase change material is in a solid state, a gap is reserved between its four side walls and the side pressure plate; The telescopic rod has a reciprocating up-and-down extension function driven by the pneumatic transmission system, and the airbag has a reciprocating left-and-right extension function driven by the pneumatic transmission system, so that the pressure plate produces a reciprocating up-and-down motion and the side pressure plate produces a reciprocating left-and-right motion.

[0006] Furthermore, the encapsulation mechanism includes an encapsulation substrate, a top cover is provided on the top of the encapsulation substrate; the heat conduction surface is provided at the bottom of the encapsulation substrate; the phase change material filling cavity, the side pressure plate, and the airbag are provided in the encapsulation substrate; and the telescopic rod is provided on the bottom surface of the top cover.

[0007] Furthermore, the phase change material is an organic phase change material or an inorganic phase change material, and the phase change temperature range of the phase change material is adapted to the operating temperature range of the target application scenario.

[0008] Furthermore, the phase change material is a precast block formed by casting a mold. The shape of the precast block is adapted to the shape of the phase change material filling cavity, and the area of ​​the bottom surface of the precast block facing the heat conduction surface accounts for 85% to 90% of the area of ​​the heat conduction surface, so as to reduce the adhesion resistance between the phase change material and the heat conduction surface.

[0009] Furthermore, the melting point of the pressure plate is higher than the decomposition temperature of the phase change material.

[0010] Furthermore, the area of ​​the airbag in its inflated and deployed state is equal to the area of ​​the side pressure plate.

[0011] Furthermore, the heat conduction surface is made of a metal material with a high thermal conductivity.

[0012] Furthermore, a finned extended heat transfer structure is provided on the heat conduction surface.

[0013] Furthermore, a thermally conductive interface material layer is provided on the outer surface of the thermally conductive surface. The thermally conductive interface material layer is used to adhere to the heat dissipation surface of the external heat source so that the heat from the external heat source can be transferred to the phase change material via the thermally conductive surface.

[0014] A method for actively achieving contact melting, applied to the phase change material thermal storage device as described above, includes the following steps: Endothermic phase: Step 1: The pneumatic transmission system drives the telescopic rod to move the pressure plate downward to squeeze the solid phase change material; Step two: Heat from the external heat source is transferred to the phase change material through the heat conduction surface; Step 3: When the phase change material in close contact with the heat conduction surface reaches its melting point and begins to melt, the telescopic rod continues to drive the pressure plate to press down, so that the unmelted solid phase part remains in close contact with the heat conduction surface. At the same time, the melted liquid phase layer is squeezed into the cavity space vacated after the solid phase moves, so that the phase change heat absorption process is concentrated in the liquid phase film near the heat conduction surface to achieve rapid heat charging and latent heat storage. Exothermic phase: Step four: After the phase change material is completely melted, the pneumatic transmission system drives the airbag to inflate and unfold, while the telescopic rod retracts. The side pressure plate is pushed by the airbag to squeeze the liquid phase change material, causing it to concentrate, solidify, and release heat to form a shape. Step 5: After complete solidification, the airbag is depressurized and retracted, and the side pressure plate is reset, creating a separation gap between the wall and the solidified phase change material in preparation for the next heat storage cycle.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. Constant driving force ensures the stability of the phase transition process. This invention uses a pneumatic transmission system as the driving force source. The telescopic rod can provide a constant and undiminished driving force throughout the entire melting or solidification process of the phase change material. Compared with the spring-driven method, it avoids the drawback of the thrust gradually decreasing due to the change in spring compression, and ensures that the pressure plate maintains stable extrusion on the phase change material throughout the entire phase change process, thereby ensuring the continuity and uniformity of the contact melting / solidification process.

[0016] 2. Dynamic recycling capability enables the device to be reused. By controlling the inflation and deflation of the pneumatic transmission system, the airbag can be expanded and retracted, and the telescopic rod can be extended and retracted, realizing the reciprocating motion between the container wall and the pressure plate. This drives the phase change material to dynamically cycle between a fully molten state and a fully solidified state, breaking through the technical bottleneck of existing active contact melting technology, which makes it difficult to achieve recycling. This enables the thermal storage device to have the ability to perform multiple charge and discharge cycles.

[0017] 3. Reduce pressurization thrust requirements and simplify processing technology. By setting movable side pressure plates and retracting them after solidification using airbags, a separation gap is automatically formed between the wall surface and the solidified phase change material. This eliminates the adhesion resistance between the phase change material and the wall surface, significantly reducing the pressure thrust required to achieve contact melting. Compared to the existing technology that uses an inner wall coating to reduce adhesion, this avoids the defects of complex coating processing and coating peeling failure after long-term use, reducing manufacturing costs and improving the service life and reliability of the device.

[0018] 4. Balancing power density and energy density This invention uses a pressure plate to continuously compress the solid phase, keeping it in close contact with the heat conduction surface. This concentrates the phase change heat absorption process within a thin liquid phase region near the heat conduction surface, achieving rapid heat charging (high power density). Simultaneously, the liquid phase change material is extruded and solidified by the side pressure plate during the solidification stage, fully utilizing the entire latent heat of the phase change material (high energy density). This overcomes the inherent trade-off between power density and energy density in traditional passive thermal storage solutions. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the phase change material thermal storage device of the present invention; Figure 2 This is a top view of the airbag in the phase change material thermal storage device of the present invention in the deflated state. Figure 3 This is a top view of the airbag in the phase change material thermal storage device of the present invention when it is inflated.

[0021] Explanation of reference numerals in the attached diagram: 1. Top cover; 2. Telescopic rod; 3. Pressure plate; 4. Phase change material filling cavity; 5. Encapsulation substrate; 6. Airbag; 7. Side pressure plate; 8. Heat conduction surface; "x" indicates solid phase change material, "o" indicates liquid phase change material. Detailed Implementation

[0022] like Figure 1-3As shown, a phase change material (PCM) thermal storage device includes an encapsulation mechanism. The encapsulation mechanism contains a thermal storage module and a pneumatic drive module. The thermal storage module includes a PCM filling cavity 4. A heat conduction surface 8 is provided at the bottom of the encapsulation mechanism, and an external heat source is provided on the outside of the encapsulation mechanism. The pneumatic drive module includes a telescopic rod 2, which is mounted on the top inner wall of the encapsulation mechanism. A pressure plate 3 is provided at the working end of the telescopic rod 2. Side pressure plates 7 are provided around the PCM filling cavity 4, and an airbag 6 is provided on the side of the side pressure plate 7 away from the PCM filling cavity 4. Both the telescopic rod 2 and the airbag 6 are connected to a pneumatic transmission system. The phase change material is disposed inside the phase change material filling cavity 4. The top surface of the phase change material abuts against the pressure plate 3, and the bottom surface of the phase change material abuts against the heat conduction surface 8. In the solid state, the phase change material has a gap between its four side walls and the side pressure plate 7. The telescopic rod 2 has a reciprocating up-and-down telescopic function under the drive of the pneumatic transmission system, and the airbag 6 has a reciprocating left-and-right telescopic function under the drive of the pneumatic transmission system, so that the pressure plate 3 produces a reciprocating up-and-down motion and the side pressure plate 7 produces a reciprocating left-and-right motion.

[0023] The encapsulation mechanism includes an encapsulation base 5, with a top cover 1 installed on the top of the encapsulation base 5; a heat conduction surface 8 is disposed at the bottom of the encapsulation base 5; a phase change material filling cavity 4, a side pressure plate 7, and an airbag 6 are disposed inside the encapsulation base 5; and a telescopic rod 2 is installed on the bottom surface of the top cover 1.

[0024] The phase change material is either an organic or inorganic phase change material, and its phase change temperature range is adapted to the operating temperature range of the target application scenario. In actual use, the phase change material is selected from either organic or inorganic phase change materials, with the specific type chosen based on the operating temperature range of the target application scenario.

[0025] The phase change material is a precast block formed by casting a mold. The shape of the precast block is adapted to the shape of the phase change material filling cavity 4, and the area of ​​the bottom surface of the precast block facing the heat conduction surface 8 accounts for 85% to 90% of the area of ​​the heat conduction surface 8, so as to reduce the adhesion resistance between the phase change material and the heat conduction surface 8.

[0026] The melting point of the material in the pressure plate 3 is higher than the decomposition temperature of the phase change material.

[0027] The area of ​​the airbag 6 in its inflated and deployed state is equal to the area of ​​the side pressure plate 7.

[0028] The material of the heat conduction surface is configured according to the heat transfer requirements. The heat conduction surface 8 is made of a metal material with a high thermal conductivity, or a finned extended heat transfer structure can be provided on the heat conduction surface 8.

[0029] The outer surface of the heat conduction surface 8 is provided with a thermally conductive interface material layer. The thermally conductive interface material layer is used to adhere to the heat dissipation surface of the external heat source, so as to realize the heat of the external heat source is transferred to the phase change material through the heat conduction surface 8. The thermally conductive interface material layer includes, but is not limited to, any one of thermally conductive grease, thermally conductive pads, thermally conductive gel, thermally conductive phase change material, or thermally conductive double-sided tape.

[0030] Specifically, this embodiment uses electronic device heat dissipation as an application scenario, providing a phase change material heat storage device that actively achieves contact melting. In this embodiment, the phase change material is paraffin wax, with a melting point range of 50-60℃. It is pre-cast into a rectangular block that fits the shape of the cavity 4 using a mold. The bottom area of ​​this block accounts for 87.9% of the area of ​​the heat conduction surface 8, eliminating the adhesion resistance between the paraffin wax and the wall surface and significantly reducing the pressure thrust required to achieve contact melting. The pressure plate 3 is made of ceramic, has a rectangular flat plate structure, and its size is slightly smaller than the inner cavity size of the encapsulation substrate 5, and is placed above the paraffin wax block. The encapsulation substrate 5 is made of aluminum alloy, and its bottom forms the heat conduction surface 8. The heat conduction surface 8 is made of copper, and its upper surface is integrally machined with multiple parallel needle-like fins to increase the heat exchange area. Movable side plates 7 are pre-installed on all four sides of the paraffin block, and each side plate 7 has an embedded air bladder 6. The air bladder 6 is connected to the inner wall of the encapsulation substrate 5, such as... Figure 2 As shown. The telescopic rod 2 and the airbag 6 are respectively connected to an external air source (such as a micro air pump or a pre-filled air cylinder) and a pressure relief valve through pipelines. After assembly, thermal conductive silicone grease is applied to the outer surface of the heat conduction surface 8, and this surface is then attached to the heat dissipation surface of the heat-generating electronic component, which constitutes an external heat source.

[0031] During the operation of the electronic device, the heat generated by the heat-generating electronic components is rapidly transferred to the heat conduction surface 8 via thermally conductive silicone grease. Simultaneously, the pneumatic transmission system drives the telescopic rod 2 to move the pressure plate 3 downward, squeezing the solid paraffin wax. Heat is transferred to the paraffin wax via the heat conduction surface 8. When the solid paraffin wax adhering to the heat conduction surface 8 reaches its melting point and begins to melt, the telescopic rod 2 continues to drive the pressure plate 3 downward, keeping the unmelted solid portion in close contact with the heat conduction surface 8. At the same time, the melted liquid phase layer is expelled into the cavity 4 vacated after the solid phase movement, filling the volume gaps created by melting. Thus, the phase change heat absorption process is concentrated and continuously carried out within a micron-thick liquid phase film near the heat conduction surface 8, achieving rapid heat charging and latent heat storage, thereby effectively controlling the operating temperature of the electronic device components within the normal range.

[0032] After the electronic equipment stops working, the heat storage device enters the heat release phase. At this time, the paraffin wax has completely melted, and the pneumatic transmission system drives the airbag 6 to inflate and deploy, as... Figure 3 As shown, simultaneously, the telescopic rod 2 retracts; the side pressure plate 7, pushed by the airbag 6, applies pressure to the liquid paraffin, causing it to solidify and release heat to solidify; after the paraffin has completely solidified, the airbag 6 releases air and retracts, and the side pressure plate 7 returns to its original position, creating a separation gap between the inner wall of the encapsulation substrate 5 and the solidified paraffin block, as shown. Figure 2 As shown, this is for use in the next heat storage-heat dissipation cycle.

[0033] A method for actively achieving contact melting, applied to the phase change material thermal storage device as described above, includes the following steps: Endothermic phase: Step 1: The pneumatic transmission system drives the telescopic rod 2 to move the pressure plate 3 downward to squeeze the solid phase change material. Step 2: Heat from the external heat source is transferred to the phase change material via the heat conduction surface 8; Step 3: When the phase change material in close contact with the heat conduction surface 8 reaches its melting point and begins to melt, the telescopic rod 2 continues to drive the pressure plate 3 to press down, so that the unmelted solid phase part remains in close contact with the heat conduction surface 8. At the same time, the melted liquid phase layer is squeezed into the cavity space vacated after the solid phase moves, so that the phase change heat absorption process is concentrated in the liquid phase film (the thickness of the liquid phase film is on the order of micrometers) near the heat conduction surface 8 to achieve rapid heat charging and latent heat storage. Exothermic phase: Step 4: After the phase change material is completely melted, the pneumatic transmission system drives the airbag 6 to inflate and unfold, while the telescopic rod 2 retracts. The side pressure plate 7 is pushed by the airbag 6 to squeeze the liquid phase change material, causing it to concentrate, solidify, release heat, and solidify. Step 5: After complete solidification, the airbag 6 is deflated and retracted, and the side pressure plate 7 is reset, creating a separation gap between the wall and the solidified phase change material in preparation for the next heat storage cycle.

[0034] This invention achieves a synergistic improvement in the power density and energy density of the thermal storage system, and is suitable for thermal storage operation modes that operate continuously and periodically.

[0035] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A phase change material thermal storage device, characterized in that: The package includes a packaging mechanism, which has a heat storage module and a pneumatic drive module inside. The heat storage module includes a phase change material filling cavity (4), a heat conduction surface (8) at the bottom of the packaging mechanism, and an external heat source at the outside of the packaging mechanism. The pneumatic drive module includes a telescopic rod (2), which is located on the top inner wall of the packaging mechanism. A pressure plate (3) is located at the working end of the telescopic rod (2). Side pressure plates (7) are located around the phase change material filling cavity (4). An air bag (6) is located on the side of the side pressure plate (7) away from the phase change material filling cavity (4). The telescopic rod (2) and the air bag (6) are both connected to the pneumatic transmission system. The phase change material is disposed inside the phase change material filling cavity (4), the top surface of the phase change material abuts against the pressure plate (3), and the bottom surface of the phase change material abuts against the heat conduction surface (8); when the phase change material is in a solid state, a gap is reserved between its four side walls and the side pressure plate (7); The telescopic rod (2) has a reciprocating up-and-down telescopic function under the drive of the pneumatic transmission system, and the airbag (6) has a reciprocating left-and-right telescopic function under the drive of the pneumatic transmission system, so that the pressure plate (3) generates a reciprocating up-and-down motion and the side pressure plate (7) generates a reciprocating left-and-right motion.

2. The phase change material thermal storage device according to claim 1, characterized in that: The encapsulation mechanism includes an encapsulation substrate (5), with a top cover (1) on the top of the encapsulation substrate (5); a heat conduction surface (8) is disposed at the bottom of the encapsulation substrate (5); a phase change material filling cavity (4), a side pressure plate (7), and an airbag (6) are disposed inside the encapsulation substrate (5); and a telescopic rod (2) is disposed on the bottom surface of the top cover (1).

3. The phase change material thermal storage device according to claim 1, characterized in that: The phase change material is an organic phase change material or an inorganic phase change material, and the phase change temperature range of the phase change material is adapted to the operating temperature range of the target application scenario.

4. The phase change material thermal storage device according to claim 1, characterized in that: The phase change material is a precast block formed by casting a mold. The shape of the precast block is adapted to the shape of the phase change material filling cavity (4). The area of ​​the bottom surface of the precast block facing the heat conduction surface (8) accounts for 85% to 90% of the area of ​​the heat conduction surface (8) to reduce the adhesion resistance between the phase change material and the heat conduction surface (8).

5. The phase change material thermal storage device according to claim 1, characterized in that: The melting point of the material of the pressure plate (3) is higher than the decomposition temperature of the phase change material.

6. The phase change material thermal storage device according to claim 1, characterized in that: The area of ​​the airbag (6) in its inflated and deployed state is equal to the area of ​​the side pressure plate (7).

7. The phase change material thermal storage device according to claim 1, characterized in that: The heat conduction surface (8) is made of a metal material with high thermal conductivity.

8. The phase change material thermal storage device according to claim 1, characterized in that: A ribbed extended heat transfer structure is provided on the heat conduction surface (8).

9. The phase change material thermal storage device according to claim 1, characterized in that: The outer surface of the heat conduction surface (8) is provided with a heat conduction interface material layer, which is used to fit with the heat dissipation surface of the external heat source so that the heat of the external heat source can be transferred to the phase change material through the heat conduction surface (8).

10. A method for actively achieving contact melting, applied to the phase change material thermal storage device as described in claim 1, characterized in that: Includes the following steps: Endothermic phase: Step 1: The pneumatic transmission system drives the telescopic rod (2) to move the pressure plate (3) downward to squeeze the solid phase change material; Step 2: Heat from the external heat source is transferred to the phase change material via the heat conduction surface (8); Step 3: When the phase change material in close contact with the heat conduction surface (8) reaches the melting point and begins to melt, the telescopic rod (2) continues to drive the pressure plate (3) to press down, so that the unmelted solid phase part remains in close contact with the heat conduction surface (8), while the melted liquid phase layer is squeezed into the cavity space vacated after the solid phase moves, so that the phase change heat absorption process is concentrated in the liquid phase film near the heat conduction surface (8) to achieve rapid heat charging and latent heat storage; Exothermic phase: Step 4: After the phase change material is completely melted, the pneumatic transmission system drives the airbag (6) to inflate and unfold, while the telescopic rod (2) retracts. The side pressure plate (7) applies pressure to the liquid phase change material under the push of the airbag (6), causing it to concentrate, solidify, and release heat to form a shape. Step 5: After complete solidification, the airbag (6) is deflated and retracted, and the side pressure plate (7) is reset, so that a separation gap is created between the wall and the solidified phase change material in preparation for the next heat storage cycle.

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