High-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface structure

Abstract

This invention discloses a high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure, belonging to the field of phase change thermal storage technology. The phase change thermal storage capsule includes a capsule shell and a phase change material filled within the capsule shell; the capsule shell is a sealed structure composed of an optimized three-period minimal curved surface porous skeleton and phase-adaptive baffles. The unique geometric characteristics, high tortuosity, and complex topology of the optimized three-period minimal curved surface porous skeleton in the phase change thermal storage capsule of this invention significantly improve the thermal storage rate and total heat storage capacity compared to traditional spherical phase change capsules. This invention promotes rapid thermal storage in phase change material capsule-filled bed systems while increasing the heat storage capacity, providing a feasible optimization direction for the design of high-performance filled bed phase change thermal storage systems.

Description

Technical Field

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

[0002] In high-performance electronic devices such as those used in spacecraft and satellites, electronic components typically operate in pulsed patterns, resulting in high heat flux densities generated within short periods. This rapid heat accumulation necessitates an effective thermal management system to ensure stable equipment operation. Thermal storage units (TSVs) offer significant advantages as thermal buffers for electronic components, effectively improving temperature stability under varying heat loads. However, spacecraft and satellites have stringent weight requirements; therefore, TSVs must be miniaturized while possessing high heat storage rates and capacities to achieve excellent heat dissipation performance while maintaining a low weight.

[0003] Phase change capsule-filled bed thermal energy storage systems are characterized by their simple design and high heat storage rate. This system effectively stores and regulates heat by filling a bed with phase change material capsules and utilizing a heat transfer fluid circulating within the bed to absorb or release heat. However, given the stringent requirements for weight, volume, and thermal response speed in spacecraft and satellites, traditional spherical capsule structures have limitations in terms of heat storage per unit volume and heat storage rate, making it difficult to fully meet the demands for rapid and efficient thermal management.

[0004] Tri-periodic minimal surface structures (TPMS) possess a periodic, continuous surface framework and a large specific surface area, enabling them to provide more ordered and efficient thermal networks in heat transfer applications. With the rapid development of additive manufacturing technology, the precise fabrication of complex topologies has become increasingly feasible, providing a new approach for phase change capsule design. Introducing TPMS structures into phase change capsule design holds promise for overcoming the performance limitations of traditional structures. However, typical TPMS structures cannot simultaneously outperform traditional spherical structures in both the two key performance aspects of heat storage per unit volume and heat storage rate. For example, among common TPMS structures, only the Primitive structure capsule has a higher encapsulated phase change material volume fraction than traditional spherical capsules, possessing the potential to increase heat storage per unit volume, but its heat storage rate is lower than that of spherical capsules.

[0005] Therefore, this invention designs a novel three-period minimal curved surface phase change capsule to achieve a dual improvement in heat storage per unit volume and heat storage rate, thereby promoting the application of phase change capsule filled bed thermal storage systems in the thermal management of spacecraft and satellite electronic equipment. Summary of the Invention

[0006] In order to simultaneously improve the heat storage capacity and heat storage rate per unit volume of the phase change thermal storage capsule, this invention improves the original Primitive structure and designs a high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure.

[0007] The technical solution of this invention is as follows:

[0008] A high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure includes a capsule shell and a phase change material filled inside the capsule shell; the capsule shell is a sealed structure composed of an optimized three-period minimal curved surface porous skeleton and phase-adaptive baffles; the optimized three-period minimal curved surface porous skeleton structure is formed by a hybrid of Primitive-type three-period minimal curved surfaces and Diamond-type three-period minimal curved surfaces; the baffles cover the open boundary of the optimized three-period minimal curved surface skeleton.

[0009] Furthermore, the governing equation for the optimized generation of the three-period minimal surface porous framework is:

[0010]

[0011] In the formula, , and It is a spatial rectangular coordinate system established in the skeletal cell. axis, shaft and The coordinates of the axis; It is a coefficient used to control the size of the skeleton; It is a constant used to control the porosity of the overall structure; It is the hybridization coefficient.

[0012] Furthermore, The value ranges from 0.32 to 0.4.

[0013] Furthermore, the size of the phase change thermal storage capsule =10~60 mm; the thickness of the optimized three-period minimal surface skeleton is 0.09 mm. The thickness of the stop block is 0.09 mm. .

[0014] Furthermore, the stop includes a flat portion and an outer contour designed according to the open boundary of an optimized three-period minimal surface skeleton, forming a follow-up adaptation structure.

[0015] Furthermore, there are 6 blocks, one of which has a reserved hole for filling phase change material. The reserved hole is located on the straight part of the block to facilitate the filling operation of phase change material. After filling, the reserved hole is sealed by welding.

[0016] Furthermore, the pre-drilled hole on the stop block is square, with a side length of 0.15. .

[0017] Furthermore, the optimized three-period minimal curved surface skeleton and the stop block are integrally formed by 3D printing to ensure the airtightness of the capsule shell.

[0018] Furthermore, the optimized three-period minimal surface skeleton and the stop 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 hydrated crystalline salts.

[0019] Furthermore, the phase change material is filled into the capsule shell by vacuum impregnation, and the filling rate of the phase change material in the liquid state is controlled at 95% during the filling process.

[0020] The beneficial effects of this invention are as follows: This invention designs a high-efficiency phase change thermal storage capsule that utilizes an optimized Primitive-type three-period minimal curved surface shell to encapsulate phase change material, possessing significant technical advantages. Specifically, these advantages are manifested in:

[0021] In the first aspect, the unique geometric characteristics of the optimized three-period minimal curved porous skeleton enable the capsule to encapsulate more phase change materials. Compared with traditional spherical capsules, it can store more heat in the same volume, significantly improving the heat storage capacity and meeting the demand for large heat storage.

[0022] Secondly, the optimized three-period minimal surface porous framework possesses high tortuosity, and its complex topology generates a strong disturbance effect when external fluid flows through the outer wall of the capsule. This disturbance helps to break the fluid boundary layer, reduce thermal resistance, and thus further enhance the heat transfer process, improving the heat transfer rate and thermal response rate.

[0023] In summary, this invention can play a key role in the thermal management of spacecraft, satellites and other high-performance electronic devices, meeting the demand for efficient, reliable and lightweight thermal management technologies. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural diagram of the high-efficiency phase change thermal storage capsule coated with an optimized Primitive-type three-period minimal surface (α=0.4) in Embodiment 1 of the present invention.

[0025] Figure 2 This is a three-dimensional cross-sectional view of the high-efficiency phase change thermal storage capsule coated with an optimized Primitive-type three-period minimal surface (α=0.4) in Embodiment 1 of the present invention.

[0026] Figure 3This is a diagram showing the effect of phase change material filling inside the high-efficiency phase change thermal storage capsule coated with an optimized Primitive-type three-period minimal surface (α=0.4) in Embodiment 1 of the present invention.

[0027] Figure 4 This is a three-dimensional structural diagram of the stop block in Embodiment 1 of the present invention, wherein (a) shows a block with a pre-drilled hole and (b) shows a block without a pre-drilled hole.

[0028] Figure 5 This is a three-dimensional structural diagram of the high-efficiency phase change thermal storage capsule coated with an optimized Primitive-type three-period minimal surface (α=0.32) in Embodiment 2 of the present invention.

[0029] Figure 6 (a) is a three-dimensional structural diagram of the conventional spherical phase change thermal storage capsule used in Comparative Example 1 of the present invention.

[0030] Figure 6 (b) is a three-dimensional structural diagram of the phase change thermal storage capsule with original Primitive type three-period minimal curved surface covered by Comparative Example 2 of the present invention.

[0031] Figure 6 (c) is a three-dimensional structural diagram of the phase change thermal storage capsule covered by the optimized Primitive type three-period minimal surface (α=0.5) in Comparative Example 3 of the present invention.

[0032] Figure 7 This is a real-time power comparison of Examples 1 and 2 with Comparative Examples 1, 2 and 3.

[0033] In the figure: 1. Block with pre-drilled holes; 2. Optimized three-cycle minimal curved surface porous skeleton; 3. Block without pre-drilled holes; 4. Phase change material. Detailed Implementation

[0034] The embodiments of this application are described in detail below with reference to the accompanying drawings, examples of which are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0035] like Figure 1 , Figure 2As shown, this invention proposes a high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure, comprising a capsule shell and a phase change material 4 filled inside the capsule shell. The capsule shell includes a block 1 with pre-drilled holes, five blocks 3 without pre-drilled holes, and an optimized three-period minimal curved surface porous skeleton 2. The outer contours of the blocks 1 with pre-drilled holes and the blocks 3 without pre-drilled holes are designed according to the open boundaries of the optimized three-period minimal curved surface skeleton, forming a responsive adaptation structure. The responsive adaptation structure is tightly connected to the six open boundaries of the optimized three-period minimal curved 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 pre-drilled holes on the blocks using a vacuum impregnation method, and the filling effect is as shown. Figure 3 As shown; after filling, the reserved holes are sealed by welding.

[0036] The governing equations for generating the optimized three-period minimal surface porous framework 2 are as follows:

[0037]

[0038] in, , and It is a spatial rectangular coordinate system established in the skeletal cell. axis, shaft and The coordinates of the axis; It is the hybridization coefficient, with a value ranging from 0.32 to 0.4; =10~60 mm; the optimized thickness of the three-period minimal surface skeleton 2 is 0.09 mm. The thickness of the stop block is 0.09 mm. .

[0039] The pre-drilled block 1, the block 3 without pre-drilled holes, and the optimized three-cycle minimal curved 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 hydrated crystal salts; the filling rate of the liquid phase change material 4 inside the capsule shell is controlled at 95%.

[0040] Example 1

[0041] This embodiment designs a high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure, consisting of a capsule shell and a phase change material 4 filled inside the capsule shell. The capsule shell is manufactured using 3D printing technology (selective laser melting) using a pre-drilled hole block 1, five pre-drilled hole-free block blocks 3, and an optimized three-period minimal curved surface porous skeleton 2. The optimized three-period minimal curved surface porous skeleton 2 is formed by hybridizing Primitive-type three-period minimal curved surfaces and Diamond-type three-period minimal curved surfaces, with a hybridization coefficient of... Overall size =10 mm, the capsule shell thickness is 0.9 mm, and the side length of the square pre-drilled 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.

[0042] Table 1 Thermophysical properties

[0043]

[0044] Example 2: Based on Example 1, the hybridization coefficient of the optimized three-period minimal surface porous framework 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 pre-drilled hole is 1.5 mm (consistent with Example 1).

[0045] Comparative Example 1: Based on Example 1, the optimized three-period minimal curved porous skeleton capsule shell in Example 1 was 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).

[0046] Comparative Example 2: Based on Example 1, the optimized three-period minimal surface porous framework capsule shell in Example 1 was replaced with the original Primitive type three-period minimal surface porous framework, such as... Figure 6 As shown in (b), the capsule size =10 mm, and the capsule shell thickness is 0.9 mm (consistent with Example 1).

[0047] Comparative Example 3: Based on Example 1, the hybridization coefficient of the optimized three-period minimal surface porous framework 2 in Example 1 was changed to... .like Figure 6 As shown in (c), the overall dimensions of Comparative Example 3 =10 mm, the capsule shell thickness is 0.9 mm, and the side length of the square pre-drilled hole is 1.5 mm (consistent with Example 1).

[0048] 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 × 10⁻⁶. -7 m 3 The capsule shell has a volume of 2.3 × 10⁻⁶. -7 m 3 The volume of the encapsulated phase change material is 2.88 × 10⁻⁶. -7 m 3 In Example 1, the volume of the optimized three-period minimum curved surface-coated high-efficiency phase change thermal storage capsule when α=0.4 is 6.1×10⁻⁶. -7 m 3 The capsule shell has a volume of 3.01 × 10⁻⁶. -7 m 3 The volume of the encapsulated phase change material is 3.08 × 10⁻⁶. -7 m 3 In Example 2, when α=0.32, the volume of the optimized three-period minimal curved surface-coated high-efficiency phase change thermal storage capsule is 6.2×10⁻⁶. -7 m 3 The capsule shell has a volume of 3.21 × 10⁻⁶. -7 m 3 The volume of the encapsulated phase change material is 2.99 × 10⁻⁶. -7 m 3 In Example 1, when α=0.4, the volume of the optimized three-period minimal curved surface-coated high-efficiency phase change thermal storage capsule increased by 16.4% compared to the spherical capsule. In Example 2, when α=0.32, the volume of the optimized three-period minimal curved surface-coated high-efficiency phase change thermal storage capsule increased by 18.3% compared to the spherical capsule. The increase in phase change capsule volume significantly improved the heat storage per unit volume. For example, when the heat exchange fluid temperature was 348 K and the initial temperature of the phase change capsule was 300 K, the theoretical maximum heat storage of the spherical phase change capsule in Comparative Example 1 was 81.5 J, and the theoretical maximum heat storage of the optimized three-period minimal curved surface-coated high-efficiency phase change thermal storage capsule in Example 1 was 93.8 J, which is 15.0% higher than that of the spherical phase change thermal storage capsule in Comparative Example 1.

[0049] Table 2 Phase Change Capsule Volume

[0050]

[0051] The melting and heat transfer process of three phase change thermal storage capsules was simulated, with an inlet velocity of 0.04 m / s and a temperature of 348 K for the heat transfer fluid. The real-time heat transfer power variation curves for Examples 1, 2, and Comparative Examples 1, 2, and 3 are shown below. Figure 7As shown in Table 3, the peak and average heat transfer rates during the heat transfer process are as follows. The results indicate that the heat transfer rate of the phase change capsule increases rapidly within a short time after the start of heat exchange. Specifically, the peak heat transfer rate of the original Primitive three-period minimal curved 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. In Comparative Example 3, the peak heat transfer rate of the three-period minimal curved surface phase change capsule with α=0.5 is 21.53 W, 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 curved surface phase change capsule with α=0.4 in Example 1 of this invention is 22.34 W, which is 1.4% higher than that of the spherical phase change capsule in Comparative Example 1. This demonstrates that the optimized Primitive three-period minimal curved surface phase change capsule in Example 1 of this invention improves upon the insufficient peak heat transfer rate of the original Primitive three-period minimal curved surface phase change capsule in Comparative Example 2. In Example 2 of this invention, the peak heat transfer rate of the optimized three-period minimal curved phase change capsule with α=0.32 is 24.26 W, which is 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 as the hybridization coefficient α decreases. α=0.32~0.4 is the preferred hybridization coefficient range.

[0052] For the average heat transfer rate in the first 20 seconds of the thermal storage process, Comparative Example 1's spherical phase change capsule achieved 3.07 W, while Comparative Example 2's original Primitive three-period minimal curved surface phase change capsule achieved 3.62 W, ​​representing a 17.9% improvement over Comparative Example 1's spherical phase change capsule. In Example 1 of this invention, the optimized three-period minimal curved surface phase change capsule, with α=0.4, further improved the average heat transfer rate to 3.93 W, a 28.0% improvement over Comparative Example 1's spherical phase change capsule. In Example 2 of this invention, as the hybridization coefficient α decreased to 0.32, the optimized three-period minimal curved surface phase change capsule further improved the average heat transfer rate to 4.16 W, a 35.5% improvement over Comparative Example 1's spherical phase change capsule.

[0053] Table 3 Heat transfer rate

[0054]

[0055] Therefore, the high-efficiency phase change thermal storage capsule based on the optimized Primitive-type three-period minimal curved surface covering structure proposed in this invention is superior to traditional spherical phase change capsules in terms of peak heat transfer rate, average heat transfer rate and total heat storage, thus promoting the application of phase change capsule filled bed thermal storage systems in the thermal management of spacecraft and satellite electronic equipment.

[0056] Although the above embodiments have described the technical solutions of the present invention in detail, they are only some preferred embodiments and not all embodiments of the present invention. Other embodiments obtained through non-creative effort based on these embodiments without departing from the spirit and principles of the present invention, as well as any modifications, equivalent substitutions, or improvements thereof, are all within the protection scope of the claims of the present invention.

Claims

1. A high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure, characterized in that, The system includes a capsule shell and a phase change material filled within the capsule shell. The capsule shell is a sealed structure composed of an optimized three-period minimal surface porous framework and a phase-adaptive baffle. The optimized three-period minimal surface porous framework is formed by a hybrid of Primitive-type and Diamond-type three-period minimal surfaces. The baffle covers the open boundary of the optimized three-period minimal surface porous framework. The governing equations for generating the optimized three-period minimal surface porous framework are: In the formula, , and It is a spatial rectangular coordinate system established in the skeletal cell. axis, shaft and The coordinates of the axis; It is a coefficient used to control the size of the skeleton; It is a constant used to control the porosity of the overall structure; It is the hybridization coefficient.

2. The high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure according to claim 1, characterized in that, The value ranges from 0.32 to 0.

4.

3. The high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure according to claim 1 or 2, characterized in that, The size of the phase change thermal storage capsule =10~60 mm; the thickness of the optimized three-period minimal curved surface porous skeleton is 0.09 mm. The thickness of the stop block is 0.09 mm. .

4. The high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure according to claim 3, characterized in that, The stop block includes a flat portion and an outer contour designed based on the open boundary of an optimized three-period minimal surface porous skeleton, forming a follow-up adaptive structure.

5. The high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure according to claim 4, characterized in that, The number of blocks is 6, one of which has a reserved hole for filling phase change material, and the reserved hole is located on the straight part of the block.

6. The high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure according to claim 5, characterized in that, The pre-drilled hole on the stop block is square with a side length of 0.

15. .

7. The high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure according to claim 1, characterized in that, The optimized three-cycle minimal curved surface porous skeleton and the stop block are integrally formed by 3D printing.

8. The high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure according to claim 1, characterized in that, The optimized three-period minimal surface porous framework and the baffle are made of metal; the phase change material is a solid-liquid phase change material, including organic phase change materials and inorganic phase change materials.

9. The high-efficiency phase change thermal storage capsule based on an optimized Primitive-type three-period minimal curved surface covering structure according to claim 1, 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 the liquid state is controlled at 95% during the filling process.

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