Efficient phase change heat storage capsule based on optimized Priactive type three-period minimal curved surface coating structure

Abstract

The invention discloses an efficient phase change heat storage capsule based on an optimized Priactive type three-period minimal curved surface coating structure, and belongs to the technical field of phase change heat storage. The phase change heat storage capsule comprises a capsule shell and a phase change material filled in the capsule shell, the capsule shell is of a sealing structure composed of an optimized three-period extremely-small-curved-surface porous framework and a check block matched with the optimized three-period extremely-small-curved-surface porous framework. According to the phase change heat storage capsule disclosed by the invention, unique geometrical characteristics, relatively high tortuosity and a complex topological structure of the three-period extremely-small-curved-surface porous framework are optimized, so that the heat storage rate and the total heat storage capacity of the phase change heat storage capsule are remarkably improved compared with those of a traditional spherical phase change capsule; the heat storage capacity can be increased while rapid heat storage of the phase change material capsule packed bed system is promoted, and a feasible optimization direction is provided for design of the high-performance packed bed phase change heat storage system.

Description

Technical Field

[0001] The present invention belongs to the field of phase change heat storage technology, and relates to a high-efficiency phase change heat storage capsule based on an optimized primitive three-period minimal curved surface coating structure, which realizes efficient and high-density storage of thermal energy. Background Art

[0002] In high-performance electronic devices such as spacecraft and satellites, electronic devices are often operated in a pulsed manner, resulting in high heat flux density in a short period of time. This rapid heat accumulation requires an effective thermal management system to ensure stable operation of the equipment. Thermal energy storage units have significant advantages as thermal buffers for electronic devices, and can effectively improve the temperature stability of electronic devices when the heat load changes. However, spacecraft and satellites have strict requirements on weight. Therefore, thermal energy storage units must be miniaturized while having a high heat storage rate and heat storage capacity to achieve excellent heat dissipation performance while ensuring low weight.

[0003] Phase-change capsule-packed bed thermal energy storage systems feature simple design and high heat storage rates. This system effectively stores and regulates heat by filling a bed with phase-change material capsules and circulating a heat transfer fluid through the bed to absorb or release heat. However, given the stringent weight, volume, and thermal response requirements of spacecraft and satellites, traditional spherical capsule structures face bottlenecks in both heat storage per unit volume and heat storage rate, making them inadequate for rapid and efficient thermal management.

[0004] Tri-periodic minimal surface structures (TPMS) have a periodic, continuous surface skeleton and a huge specific surface area, which can provide a more orderly and efficient thermal network in the field of heat transfer. With the rapid development of additive manufacturing technology, the precise processing of complex topological structures has become increasingly feasible, providing a new approach for the design of phase change capsules. Introducing TPMS structures into the design of phase change capsules is expected to break through the performance limitations of traditional structures. However, typical TPMS structures cannot simultaneously outperform traditional spherical structures in two key performance aspects: heat storage per unit volume and heat storage rate. For example, among common TPMS structures, only the Primitive structure capsule has a higher volume fraction of encapsulated phase change material than traditional spherical capsules, which has the potential to increase heat storage per unit volume, but its heat storage rate is lower than that of spherical capsules.

[0005] Therefore, the present invention achieves a dual improvement in heat storage capacity and heat storage rate per unit volume by designing a new three-period minimal surface phase change capsule, promoting the application of phase change capsule packed bed heat storage system in thermal management of spacecraft and satellite electronic equipment. Summary of the Invention

[0006] In order to simultaneously improve the heat storage per unit volume and heat storage rate of the phase change heat storage capsule, the present invention improves the original Primitive structure and designs a high-efficiency phase change heat storage capsule based on the optimized Primitive three-periodic minimal surface coating structure.

[0007] The technical solution of the present invention is: A high-efficiency phase-change heat storage capsule based on an optimized primitive three-periodic minimal surface coating structure comprises a capsule shell and a phase-change material filled in the capsule shell; the capsule shell is a sealed structure composed of an optimized three-periodic minimal surface porous skeleton and a corresponding block; the optimized three-periodic minimal surface porous skeleton structure is formed by hybridizing a primitive three-periodic minimal surface and a diamond three-periodic minimal surface; the block covers the open boundary of the optimized three-periodic minimal surface skeleton.

[0008] Furthermore, the governing equation for the generation of the optimized three-periodic minimal surface porous skeleton is: Where, , and It is the spatial rectangular coordinate system established by the skeleton cell axis, Axis and axis coordinates; is the coefficient used to control the size of the skeleton; is a constant used to control the porosity of the overall structure; is the hybridization coefficient.

[0009] Furthermore, The value ranges from 0.32 to 0.4.

[0010] Furthermore, the size of the phase change heat storage capsule is =10~60 mm; the thickness of the optimized three-periodic minimal surface skeleton is 0.09 ; The thickness of the block is 0.09 .

[0011] Furthermore, the stopper includes a straight portion and an outer contour designed according to an open boundary of an optimized three-periodic minimal surface skeleton, forming a follow-up adaptive structure.

[0012] Furthermore, there are 6 blocks, one of which is provided with a reserved hole for filling the phase change material. The reserved hole is located in the straight part of the block to facilitate the filling operation of the phase change material. After the filling is completed, the reserved hole is sealed by a welding process.

[0013] Furthermore, the reserved hole on the block is a square, and the side length of the square reserved hole is 0.15 .

[0014] Furthermore, the optimized three-period minimal surface skeleton and the stopper are integrally formed through 3D printing to ensure the sealing of the capsule shell.

[0015] Furthermore, the optimized three-periodic minimal surface skeleton and the block are made of metal; the phase change material is a solid-liquid phase change material, including organic phase change materials such as paraffin, erythritol or acetic acid and inorganic phase change materials such as crystalline hydrated salt.

[0016] Furthermore, the phase change material is filled into the capsule shell by a vacuum impregnation method, and during the filling process, the filling rate of the phase change material in liquid state is controlled to be 95%.

[0017] Beneficial effects of the present invention: The present invention designs a high-efficiency phase change heat storage capsule using an optimized Primitive type three-period minimal surface shell to cover a phase change material, which has significant technical advantages. Specifically, it is reflected in: On the first aspect, the unique geometric properties of the optimized three-periodic minimal surface porous skeleton enable more phase change materials to be encapsulated inside the capsule. Compared with traditional spherical capsules, it can store more heat in the same volume, significantly improve the heat storage capacity, and meet the demand for large heat storage.

[0018] Secondly, the optimized three-periodic minimal surface porous framework exhibits high tortuosity. Its complex topology creates a strong disturbance effect when the external fluid flows through the capsule's outer wall. This disturbance helps break up the fluid boundary layer, reducing thermal resistance, thereby further enhancing the heat transfer process and increasing both the heat transfer rate and the thermal response rate.

[0019] In summary, the present invention can play a key role in the thermal management of spacecraft, satellites and other high-performance electronic equipment, meeting the demand for efficient, reliable and lightweight thermal management technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a three-dimensional structural diagram of a high-efficiency phase-change heat storage capsule coated with an optimized primitive three-periodic minimal surface (α=0.4) in Example 1 of the present invention.

[0021] Figure 2 This is a three-dimensional cross-sectional structure diagram of a high-efficiency phase-change heat storage capsule coated with an optimized primitive three-periodic minimal surface (α=0.4) in Example 1 of the present invention.

[0022] Figure 3This is a diagram showing the filling effect of the phase change material inside the high-efficiency phase change heat storage capsule coated with the optimized Primitive three-periodic minimal surface (α=0.4) in Example 1 of the present invention.

[0023] Figure 4 3D structural diagram of the stopper in Example 1 of the present invention, wherein (a) is with a reserved hole and (b) is without a reserved hole.

[0024] Figure 5 This is a three-dimensional structural diagram of a high-efficiency phase-change heat storage capsule coated with an optimized primitive three-periodic minimal surface (α=0.32) in Example 2 of the present invention.

[0025] Figure 6 (a) is a three-dimensional structural diagram of the traditional spherical phase change heat storage capsule used in Comparative Example 1 of the present invention.

[0026] Figure 6 (b) is a three-dimensional structural diagram of a phase change heat storage capsule coated with a primitive three-periodic minimal surface in comparative example 2 of the present invention.

[0027] Figure 6 (c) is a three-dimensional structural diagram of the phase change heat storage capsule coated with the optimized primitive three-periodic minimal surface (α=0.5) in comparative example 3 of the present invention.

[0028] Figure 7 This is a real-time power comparison between Example 1, Example 2 and Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0029] In the figure: 1. Block with reserved holes; 2. Optimized three-periodic minimal surface porous skeleton; 3. Block without reserved holes; 4. Phase change material. DETAILED DESCRIPTION

[0030] The embodiments of the present application are described in detail below with reference to the accompanying drawings, examples of which are shown in the accompanying drawings, wherein the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions.

[0031] like Figure 1 、 Figure 2As shown, the present invention proposes a high-efficiency phase change heat storage capsule based on an optimized Primitive type three-period minimal surface coating structure, including a capsule shell and a phase change material 4 filled in the capsule shell. The capsule shell includes a block 1 with a reserved hole, five blocks 3 without reserved holes, and an optimized three-period minimal surface porous skeleton 2; the outer contours of the block 1 with a reserved hole and the block 3 without a reserved hole are designed according to the open boundary of the optimized three-period minimal surface skeleton to form a follow-up adaptive structure, and the follow-up adaptive structure is tightly connected to the six open boundaries of the optimized three-period minimal surface porous skeleton 2 to form a sealed space, and the connection method is integrated 3D printing. The phase change material 4 is filled into the capsule shell through the reserved holes on the block by vacuum impregnation, and the filling effect is as follows. Figure 3 As shown; after filling is completed, the reserved hole is sealed using welding technology.

[0032] The control equation for the generation of the optimized three-periodic minimal surface porous skeleton 2 is: in, , and It is the spatial rectangular coordinate system established by the skeleton cell axis, Axis and axis coordinates; is the hybridization coefficient, ranging from 0.32 to 0.4; =10~60 mm; the thickness of the optimized three-periodic minimal surface skeleton 2 is 0.09 ; The thickness of the stopper is 0.09 .

[0033] The block 1 with pre-reserved holes, the block 3 without pre-reserved holes and the optimized three-period minimal surface porous skeleton 2 are all made of metal materials such as aluminum alloy and stainless steel; the phase change material 4 is made of organic phase change materials such as paraffin, erythritol or acetic acid and inorganic phase change materials such as crystalline hydrated salt; the filling rate of the liquid phase change material 4 in the capsule shell is controlled to be 95%.

[0034] Example 1 This embodiment designs a high-efficiency phase change heat storage capsule based on an optimized primitive three-period minimal surface coating structure, which consists of a capsule shell and a phase change material 4 filled in the capsule shell; the capsule shell is made of a block 1 with a reserved hole, five blocks 3 without reserved holes and an optimized three-period minimal surface porous skeleton 2 through 3D printing technology (selective laser melting); the optimized three-period minimal surface porous skeleton 2 is hybridized by primitive three-period minimal surface and diamond three-period minimal surface, and the hybridization coefficient is 1. , overall size =10 mm, the capsule shell thickness is 0.9 mm, and the side length of the square reserved hole is 1.5 mm. The phase change material 4 is paraffin (C 16 H 34 ), the capsule shell material is aluminum alloy (AlSi10Mg); the heat exchange fluid is liquid water.

[0035] Table 1 Thermophysical properties Example 2: Based on Example 1, the hybridization coefficient of the optimized three-periodic minimal surface porous skeleton 2 in Example 1 is changed to .like Figure 5 As shown, the overall dimensions of Example 2 =10 mm, the capsule shell thickness is 0.9 mm, and the side length of the square reserved hole is 1.5 mm (consistent with Example 1).

[0036] Comparative Example 1: Based on Example 1, the optimized three-periodic minimal surface porous skeleton capsule shell in Example 1 is replaced with a spherical shell structure, such as Figure 6 As shown in (a), the outer surface diameter of the capsule shell is 10 mm, the inner surface diameter is 8.2 mm, and the thickness is maintained at 0.9 mm (consistent with Example 1).

[0037] Comparative Example 2: Based on Example 1, the optimized three-periodic minimal surface porous skeleton capsule shell in Example 1 is replaced with the original primitive three-periodic minimal surface porous skeleton, such as Figure 6 (b) As shown, capsule size =10 mm, and the capsule shell thickness is 0.9 mm (consistent with Example 1).

[0038] Comparative Example 3: Based on Example 1, the hybridization coefficient of the optimized three-periodic minimal surface porous framework 2 in Example 1 is changed to .like Figure 6 (c) shows the overall dimensions of Comparative Example 3 =10 mm, the capsule shell thickness is 0.9 mm, and the side length of the square reserved hole is 1.5 mm (consistent with Example 1).

[0039] First, the volume comparison of phase change capsules is shown in Table 2. The volume of the spherical phase change thermal storage capsule in Comparative Example 1 is 5.24×10 -7 m 3 , where the capsule shell volume is 2.3×10 -7 m 3 The volume of the encapsulated phase change material is 2.88×10 -7 m 3In Example 1, when α = 0.4, the volume of the high-efficiency phase change heat storage capsule coated with the three-period minimal surface is 6.1×10 -7 m 3 , where the capsule shell volume is 3.01×10 -7 m 3 The volume of the encapsulated phase change material is 3.08×10 -7 m 3 In Example 2, when α=0.32, the volume of the high-efficiency phase change thermal storage capsule coated with the optimized three-period minimal surface is 6.2×10 -7 m 3 , where the capsule shell volume is 3.21×10 -7 m 3 The volume of the encapsulated phase change material is 2.99×10 -7 m 3 . In Example 1, when α=0.4, the volume of the high-efficiency phase change heat storage capsule coated with the optimized three-period minimal curved surface increases by 16.4% compared with the spherical capsule. In Example 2, when α=0.32, the volume of the high-efficiency phase change heat storage capsule coated with the optimized three-period minimal curved surface increases by 18.3% compared with the spherical capsule. The increase in the volume of the phase change capsule significantly increases the heat storage capacity per unit volume. For example, when the temperature of the heat exchange fluid is 348 K and the initial temperature of the phase change capsule is 300 K, the theoretical maximum heat storage capacity of the spherical phase change capsule of Comparative Example 1 is 81.5 J, and the theoretical maximum heat storage capacity of the high-efficiency phase change heat storage capsule coated with the optimized three-period minimal curved surface of Example 1 is 93.8 J, which is 15.0% higher than that of the spherical phase change heat storage capsule of Comparative Example 1.

[0040] Table 2 Volume of phase change capsules The melting heat transfer process of three phase change heat storage capsules was simulated, with the heat exchange fluid inlet velocity of 0.04 m / s and the temperature of 348 K. The real-time change curves of heat transfer power of Example 1, Example 2 and Comparative Example 1, Comparative Example 2 and Comparative Example 3 are shown in Figure 2. Figure 7The peak heat transfer rate and average heat transfer rate during the heat transfer process are shown in Table 3. The results show that the heat transfer rate of the phase change capsule increases rapidly in a short time after the start of heat exchange. The peak heat transfer rate of the original primitive three-period minimal surface phase change capsule in comparative example 2 is 20.34 W, which is 7.7% lower than that of the spherical phase change capsule in comparative example 1. The peak heat transfer rate of the three-period minimal surface phase change capsule in comparative example 3 when α=0.5 is 21.53 W, which is still 2.3% lower than that of the spherical phase change capsule in comparative example 1. In contrast, the peak heat transfer rate of the optimized three-period minimal surface phase change capsule in Example 1 of the present invention when α=0.4 is 22.34 W, which is 1.4% higher than that of the spherical phase change capsule in comparative example 1. This shows that the optimized primitive three-period minimal surface phase change capsule in Example 1 of the present invention improves the problem of insufficient peak heat transfer rate of the original primitive three-period minimal surface phase change capsule in comparative example 2. The peak heat transfer rate of the optimized three-period minimal surface phase change capsule in Example 2 of the present invention when α = 0.32 is 24.26 W, 10.1% higher than that of the spherical phase change capsule in Comparative Example 1. This indicates that the peak heat transfer rate of the phase change capsule further increases with decreasing hybridization coefficient α. The optimal hybridization coefficient range is α = 0.32 to 0.4.

[0041] For the average heat transfer rate in the first 20 seconds of the heat storage process, the spherical phase change capsule in Comparative Example 1 was 3.07 W, and the primitive three-period minimal surface phase change capsule in Comparative Example 2 was 3.62 W, which was 17.9% higher than the spherical phase change capsule in Comparative Example 1. In Example 1 of the present invention, when α=0.4, the average heat transfer rate of the optimized three-period minimal surface phase change capsule was further improved to 3.93 W, which was 28.0% higher than the spherical phase change capsule in Comparative Example 1. In Example 2 of the present invention, as the hybridization coefficient α decreased to 0.32, the average heat transfer rate of the optimized three-period minimal surface phase change capsule was further improved to 4.16 W, which was 35.5% higher than the spherical phase change capsule in Comparative Example 1.

[0042] Table 3 Heat transfer rate Therefore, the high-efficiency phase change heat storage capsule based on the optimized Primitive three-periodic minimal surface coating structure proposed in the present invention is superior to traditional spherical phase change capsules in terms of peak heat transfer rate, average heat transfer rate and total heat storage, promoting the application of phase change capsule packed bed heat storage system in thermal management of spacecraft and satellite electronic equipment.

[0043] Although the above embodiments describe the technical solutions of the present invention in detail, they are only some preferred embodiments of the present invention and not all implementation methods. Other embodiments obtained through non-creative work based on this embodiment without departing from the design spirit and principles of the present invention, as well as any modifications, equivalent replacements, or improvements thereto, are within the scope of protection of the claims of the present invention.

Claims

1. High-efficiency phase change thermal storage capsule based on optimized primitive three-periodic minimal surface coating structure, characterized by: It includes a capsule shell and a phase change material filled in the capsule shell; the capsule shell is a sealing structure composed of an optimized three-periodic minimal surface porous skeleton and a corresponding block; the optimized three-periodic minimal surface porous skeleton structure is formed by hybridizing primitive three-periodic minimal surfaces and diamond three-periodic minimal surfaces; the block covers the open boundary of the optimized three-periodic minimal surface skeleton.

2. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 1 is characterized in that: The governing equation for generating the optimized three-periodic minimal surface porous skeleton is: Where, , and It is the spatial rectangular coordinate system established by the skeleton cell axis, Axis and axis coordinates; is the coefficient used to control the size of the skeleton; is a constant used to control the porosity of the overall structure; is the hybridization coefficient.

3. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 2 is characterized in that: The value ranges from 0.32 to 0.

4.

4. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 2 or 3, characterized in that: The phase change heat storage capsule size =10~60 mm; the thickness of the optimized three-periodic minimal surface skeleton is 0.09 ; The thickness of the block is 0.09 .

5. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 4 is characterized in that: The stopper includes a straight portion and an outer contour designed according to an open boundary of an optimized three-periodic minimal surface skeleton, forming a follow-up adaptive structure.

6. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 5 is characterized in that: There are six blocks, one of which is provided with a reserved hole for filling the phase change material, and the reserved hole is located in the straight part of the block.

7. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 6 is characterized in that: The reserved hole on the block is square with a side length of 0.15 .

8. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 1 is characterized in that: The optimized three-period minimal surface skeleton and the stopper are integrally formed by 3D printing.

9. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 1 is characterized in that: The optimized three-periodic minimal surface skeleton and the stopper are made of metal; the phase change material is a solid-liquid phase change material, including an organic phase change material and an inorganic phase change material.

10. The high-efficiency phase change thermal storage capsule based on the optimized primitive three-periodic minimal surface coating structure according to claim 1 is characterized in that: The phase change material is filled into the capsule shell by vacuum impregnation, and the filling rate of the phase change material in liquid state is controlled at 95% during the filling process.

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