Heat transfer structure for improving thermal convection effect and its application to heat storage system

Abstract

To provide a heat transfer structure for improving a heat convection effect.SOLUTION: A heat transfer structure comprises: an area adjacent to a heat source part; an area away from the heat source part, which is installed relative to the area adjacent to the heat source part and forms a storage space between itself and the area adjacent to the heat source part; and an H-shaped fin that is installed in the storage space, and is adjacent to and connected to the area adjacent to the heat source part. The H-shaped fin includes: a first left fin connected to the area adjacent to the heat source part; a first right fin connected to the area adjacent to the heat source part, and installed opposite the first left fin; and a first intermediate plate connected to the first left fin and the first right fin. The present invention uses a special external design of the H-shaped fin structure to increase a contact area for heat exchange and generate strong natural convection, thereby rapidly accelerating the melting of a phase change material.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a heat transfer structure, and more particularly to a heat transfer structure that improves heat convection effect and its application to a thermal energy storage system. [Background technology]

[0002] In recent years, energy conservation and carbon emission reduction have become global trends, and various clean energy sources, such as renewable energy and green energy, have emerged and developed. Electric vehicles have also become mainstream in the automotive market, and at the same time, the demand for manufacturing energy storage devices is also increasing significantly. Among these, thermal energy storage systems (TES) have been widely applied in various fields, such as solar energy, thermal comfort in buildings, and industrial thermal management, and have therefore attracted extensive research attention.

[0003] There are three main types of conventional thermal energy storage technologies: sensible heat storage, thermochemical heat storage, and latent heat storage. Latent heat storage is usually an energy storage method in which the stored energy does not depend on temperature changes but on changes in the state of materials, making it highly efficient and attracting widespread market attention. Summary of the Invention [Problem to be solved by the invention]

[0004] Phase change materials used in latent heat storage have the ability to store and release large amounts of energy during the process of transitioning between solid and liquid, making them an efficient solution for mitigating temperature fluctuations in renewable energy systems. However, phase change materials in latent heat energy storage (LHTES) systems typically have low thermal conductivity, resulting in slow melting and solidification, which reduces convenience and efficiency of use and increases running costs, making them unsuitable for practical industrial applications. Therefore, there is an urgent need in the market to improve the slow melting and solidification speeds of phase change materials, shorten the phase change time of phase change materials, and increase efficiency and convenience of use.

[0005] Therefore, the present inventors believed that the above drawbacks could be improved, and as a result of extensive research, they came up with the proposal of the present invention, which effectively improves the above problems through rational design.

[0006] The present invention was made by the inventors through extensive research in view of the above problems, and a main object of the present invention is to provide a heat transfer structure that improves the thermal convection effect. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following measures. A heat transfer structure for improving thermal convection effect, which is one aspect of the present invention, includes a portion adjacent to a heat source for receiving thermal energy from the heat source, a portion away from the heat source that is provided relative to the portion adjacent to the heat source and forms an accommodation space between the portion adjacent to the heat source and the portion adjacent to the heat source, and first-layer H-shaped fins that are installed in the accommodation space and are adjacent to and connected to the portion adjacent to the heat source. The first-layer H-shaped fins include a first right fin connected to the portion adjacent to the heat source, a first left fin connected to the portion adjacent to the heat source and installed opposite the first right fin, and a first intermediate plate connected to the first left fin and the first right fin.

[0008] The heat transfer structure according to the present invention further includes a second-layer H-shaped fin disposed in the accommodation space relative to the first-layer H-shaped fin, the second-layer H-shaped fin being adjacent to a portion remote from the heat source and connected to the portion remote from the heat source, and the second-layer H-shaped fin being connected to the first-layer H-shaped fin to form an H-shaped fin structure. The second-layer H-shaped fin includes a second right fin connected to the portion remote from the heat source, a second left fin connected to the portion remote from the heat source and disposed opposite the second right fin, and a second intermediate plate connected to the second left fin and the second right fin.

[0009] Furthermore, the heat transfer structure according to the present invention further includes a connecting plate connected to the first-layer H-shaped fins and the second-layer H-shaped fins and positioned between the first-layer H-shaped fins and the second-layer H-shaped fins, wherein the first-layer H-shaped fins, the connecting plate, and the second-layer H-shaped fins collectively form the H-shaped fin structure.

[0010] In addition, the heat transfer structure of the present invention further comprises at least one first reinforcing plate connected to the first intermediate plate and a portion of the first layer H-shaped fin adjacent to the heat source and positioned between the first intermediate plate and the portion adjacent to the heat source, and / or at least one second reinforcing plate connected to the second intermediate plate and / or a portion of the second layer H-shaped fin away from the heat source and positioned between the second intermediate plate and a portion away from the heat source.

[0011] Furthermore, in the heat transfer structure of the present invention, the length of the first intermediate plate is shorter than the length of the second intermediate plate, and / or the orthogonal projection plane of the second left fin and the second right fin in the normal direction of the vicinity of the heat source is larger than the orthogonal projection plane of the first left fin and the first right fin in the normal direction of the vicinity of the heat source.

[0012] In addition, in the heat transfer structure of the present invention, a first included angle between the first right fin of the first layer H-shaped fin and the connecting plate is smaller than a second included angle between the second right fin of the second layer H-shaped fin and the connecting plate.

[0013] In the heat transfer structure according to the present invention, the portion adjacent to the heat source is an inner tube, the portion away from the heat source is an outer tube, the inner tube is disposed within the outer tube, and an annular space is formed between the outer tube and the inner tube. The H-shaped fin structure is disposed in the annular space, and the outer tube and the inner tube are disposed so as to form concentric circles with the same axis, and the outer tube and the inner tube jointly form a concentric pipe.

[0014] The heat transfer structure according to the present invention further includes N first-layer H-shaped fins, N connecting plates, and N second-layer H-shaped fins, each forming one of the N H-shaped fin structures, where N is a positive integer greater than 1.

[0015] Furthermore, in the heat transfer structure of the present invention, the third included angle between the first right fin and the first left fin of two adjacent first-layer H-shaped fins is greater than the fourth included angle between the second right fin and the second left fin of two adjacent second-layer H-shaped fins.

[0016] Another object of the present invention is to provide a heat storage device. The heat storage device according to another aspect of the present invention includes the above-described heat transfer structure and a phase change material that is installed in the storage space between a portion away from the heat source and a portion close to the heat source and that is in contact with the first-layer H-shaped fins and the second-layer H-shaped fins. [Effects of the Invention]

[0017] In this way, the heat transfer structure of the present invention increases the contact area for heat exchange through the special external design of the H-shaped fin structure, and the multiple H-shaped fin structures are arranged in a ring shape inside the concentric tube, effectively generating strong natural convection and accelerating the melting of the phase change material, solving the problem of slow natural convection and low heating efficiency of the phase change material in conventional latent heat storage systems.

[0018] At least the following points will become clear from the description and drawings to be described later. [Brief explanation of the drawings]

[0019] [Figure 1A] 1 is a schematic cross-sectional view showing a heat transfer structure for improving a thermal convection effect according to an embodiment of the present invention. [Figure 1B] FIG. 10 is a schematic cross-sectional view showing a heat transfer structure for improving a thermal convection effect according to another embodiment of the present invention. [Figure 1C]FIG. 10 is a schematic cross-sectional view showing a heat transfer structure for improving a thermal convection effect according to yet another embodiment of the present invention. [Figure 1D] FIG. 10 is a schematic cross-sectional view showing a heat transfer structure for improving a thermal convection effect according to yet another embodiment of the present invention. [Figure 2A] 1 is a schematic cross-sectional view showing a heat transfer structure for improving a thermal convection effect according to an embodiment of the present invention. [Figure 2B] 2B is a schematic cross-sectional view showing two adjacent H-shaped fin structures in the heat transfer structure shown in FIG. 2A. [Figure 2C] FIG. 2B is an external perspective view showing a heat transfer structure for improving the thermal convection effect shown in FIG. 2A. [Figure 3] 1 is a schematic diagram showing a cross-sectional structure of a heat storage device according to an embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram showing a cross-sectional structure of a heat storage device according to another embodiment of the present invention. [Figure 5] FIG. 10 is a graph showing the relationship between three different fin thicknesses and varying melting rates of the phase change material using two fixed angles of the present invention. [Figure 6] FIG. 10 is a schematic diagram showing the relationship and characteristics of the change in the ratio between the second included angle and the first included angle in the first case of the present invention. [Figure 7] FIG. 10 is a schematic diagram showing the relationship and characteristics of the change in the ratio between the second included angle and the first included angle in the second case of the present invention. [Figure 8] Flow vectors, temperature distribution (A), and liquid phase distribution (B) obtained by numerical simulation of the fin structure shown in Figure 2B. [Figure 9] 5 is a schematic curve diagram showing the relationship between the change in bending angle and the melting rate of the phase change material in the first and second cases of the present invention. FIG. [Figure 10] FIG. 10 is a bar graph showing the total energy (Etota), average power (Pm), and unit mass energy (Em) of all ratios in the first and second cases of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0021] FIG. 1A is a schematic cross-sectional view showing a heat transfer structure 1 for improving a thermal convection effect according to an embodiment of the present invention.

[0022] The heat transfer structure 1 includes a heat source vicinity 11 for receiving thermal energy from a heat source S, a portion 12 away from the heat source provided relative to the heat source vicinity 11 and forming an accommodation space 13 between the portion 12 and the heat source vicinity 11, and a first layer H-shaped fin 14 installed in the accommodation space 13, close to the heat source vicinity 11, and connected to the heat source vicinity 11. The first layer H-shaped fin 14 includes a first right fin 141 connected to the heat source vicinity 11, a first left fin 142 connected to the heat source vicinity 11 and installed opposite the first right fin 141 on the left and right sides, and a first intermediate plate 143 connected to the first left fin 142 and the first right fin 141, the first intermediate plate 143 extending along the length direction of the heat source vicinity 11 to the first left fin 142 and the first right fin 141 connected on the left and right sides. By installing the first-layer H-shaped fins 14 in the vicinity 11 of the heat source, the thermal energy received by the vicinity 11 of the heat source is directly transferred to the first-layer H-shaped fins 14 by thermal conduction. The external shape of the first-layer H-shaped fins 14 significantly increases the heat conduction area, and the heat conduction area of ​​the first-layer H-shaped fins 14 comes into contact with substances and materials in the accommodation space 13, for example, to exchange heat with heat-absorbing materials or cooling water, thereby achieving the purpose of improving the thermal convection effect.

[0023] 1A, another second layer H-shaped fin 15 extends further upward from the first layer H-shaped fin 14 and is disposed in the accommodating space 13 relative to the first layer H-shaped fin 14. The second layer H-shaped fin 15 is adjacent to and connected to the portion 12 away from the heat source. The second layer H-shaped fin 15 includes a second right fin 151 connected to the portion 12 away from the heat source, a second left fin 152 connected to the portion 12 away from the heat source and disposed opposite the second right fin 151 on the left and right sides, and a second intermediate plate 153 connected to the second left fin 152 and the second right fin 151, the second intermediate plate 153 extending along the length of the portion 12 away from the heat source to the second left fin 152 and the second right fin 151 connected on the left and right sides. In addition, the connecting plate 16 is connected to the first layer H-shaped fins 14 and the second layer H-shaped fins 15 and is located between the first layer H-shaped fins 14 and the second layer H-shaped fins 15. The first layer H-shaped fins 14, the connecting plate 16, and the second layer H-shaped fins 15 collectively form an H-shaped fin structure 17.

[0024] The first-layer H-shaped fin 14 and the second-layer H-shaped fin 15 do not necessarily have to be linear; they may be curved. As shown in FIG. 1A , the present invention may involve bending the second intermediate plate 153a of the second-layer H-shaped fin 15 into a V-shape, bending the first intermediate plate 143a of the first-layer H-shaped fin 14 into an inverted V-shape, and then connecting the first intermediate plate 143a and the second intermediate plate 153a with a connecting plate 16a. In this way, when the length of the connecting plate 16a is reduced to approximately zero, the outer shape of the first-layer H-shaped fin 14 becomes approximately W-shaped, and the outer shape of the second-layer H-shaped fin 15 becomes approximately M-shaped. In other words, the H-shaped fin structure 17 may also be a combined structure formed by directly connecting the first-layer H-shaped fin 14 to the second-layer H-shaped fin 15. Therefore, the first intermediate plate 143 of the first layer H-shaped fin 14 and the second intermediate plate 153 of the second layer H-shaped fin 15 are not limited to a linear shape but may also be arc-shaped or wavy. Incidentally, equivalent changes or modifications to the shapes of the first intermediate plate 143 and the second intermediate plate 153 can be made to transform the original H-shaped profile into an N-shape, an M-shape, or a W-shape. However, these derived structures essentially remain within the scope of the basic structure and design of the H-shaped profile of the present invention. The left and right fins first jointly define the receiving space, and then the intermediate plate is placed within the receiving space and connected to the left and right fins. In other words, the present invention does not limit the shape or position of the intermediate plate; the intermediate plate may be straight, curved, or inclined. Therefore, the present invention allows for the design of the intermediate plate to be modified as needed, and the H-shaped profile design of the present invention is actually very flexible.

[0025] Although the present invention is not limited thereto, in some embodiments, as shown in FIG. 1B , a reinforcing plate 18 extends further downward from the first layer H-shaped fin 14, and is connected to the first intermediate plate 143 of the first layer H-shaped fin 14 and the portion 11 adjacent to the heat source, and is located between the first intermediate plate 143 and the portion 11 adjacent to the heat source, and is located on the same straight line as the connecting plate 16, thereby forming a first type of modified H-shaped fin structure 17. As another option, as shown in FIG. 1B , two reinforcing plates 18 extend further downward from the first layer H-shaped fin 14, and are connected to the first intermediate plate 143 of the first layer H-shaped fin 14 and the portion 11 adjacent to the heat source, and are located between the first intermediate plate 143 and the portion 11 adjacent to the heat source, and these reinforcing plates 18 are located on straight lines different from the connecting plate 16, thereby forming a second type of modified H-shaped fin structure 17. In another embodiment, as shown in FIG. 1B, a reinforcement fin 19 extends further downward from the first layer H-shaped fin 14, and this structure has a generally inverted V-shape. The reinforcement fin 19 is connected to the first intermediate plate 143 of the first layer H-shaped fin 14 and the portion 11 adjacent to the heat source, and is located between the first intermediate plate 143 and the portion 11 adjacent to the heat source, forming a third type of modified H-shaped fin structure 17.

[0026] Referring to FIG. 1C, in some embodiments, the second layer H-shaped fin 15 may mimic the style of the first layer H-shaped fin 14, and the second layer H-shaped fin 15 further has at least one strengthening plate 18 extending upward, which is connected to the second intermediate plate 153 of the second layer H-shaped fin 15 and the portion 12 away from the heat source, and is located between the second intermediate plate 153 and the portion 12 away from the heat source, and is located on the same straight line as the connecting plate 16, forming a fourth type modified H-shaped fin structure 17. 1C , in a situation where a reinforcing plate 18 extends downward from the first layer H-shaped fin 14, two reinforcing plates 18 extend upward from the second layer H-shaped fin 15, which are connected to the second intermediate plate 153 and the portion 12 away from the heat source of the second layer H-shaped fin 15 and are located between the second intermediate plate 153 and the portion 12 away from the heat source, forming a fifth type of modified H-shaped fin structure 17. In yet another situation where a reinforcing fin 19 extends downward from the first layer H-shaped fin 14, two more reinforcing plates 18 extend upward from the second layer H-shaped fin 15, resulting in a sixth type of modified H-shaped fin structure 17. In other words, the present invention allows various derivative structures to be designed based on the basic structure of the H-shaped fin structure 17.

[0027] Therefore, the present invention modifies the shape of the basic structural components of the H-shaped fin structure 17. Referring to FIG. 1D , in some embodiments, the second middle plate 153b of the second layer H-shaped fin 15 may be extended to protrude toward the second right fin 151 and the second left fin 152, forming a seventh type of modified H-shaped fin structure 17. Alternatively, as shown in FIG. 1D , the second right fin 151c, the second left fin 152c, and the second middle plate 153c of the second layer H-shaped fin 15 are curved, and the second right fin 151c and the second left fin 152c are arranged in an eight-shape. Similarly, the first right fin 141c, the first left fin 142c, and the first middle plate 143c of the first layer H-shaped fin 14 are curved, and the first right fin 141c and the first left fin 142c are also arranged in an eight-shape, forming an eighth type of modified H-shaped fin structure 17. 1D , the second intermediate plate 153d and the first intermediate plate 143d may be designed to be wavy, and the first right fin 141d, the first left fin 142d, the second right fin 151d, and the second left fin 152d may be designed to be inclined, thereby forming a ninth type of modified H-shaped fin structure 17. Alternatively, the length of the connecting plate 16d may be reduced to nearly zero, and in this case, the low point of the wavy shape of the second intermediate plate 153d may be directly connected to the high point of the wavy shape of the first intermediate plate 143d, thereby forming a tenth type of modified H-shaped fin structure 17.

[0028] Incidentally, by installing the second-layer H-shaped fins 15 on the first-layer H-shaped fins 14, the thermal energy received by the area 11 adjacent to the heat source may be conducted to the second-layer H-shaped fins 15 by heat conduction directly through the first-layer H-shaped fins 14 (see FIG. 1A). Such a two-layer H-shaped fin structure has a significantly increased heat conduction area compared to the single-layer first-layer H-shaped fins 14. This can effectively enhance the thermal convection effect when the heat conduction areas of the first-layer H-shaped fins 14 and the second-layer H-shaped fins 15 come into contact with substances or materials in the storage space 13 to exchange heat.

[0029] Similarly, by installing the strengthening plate 18 or strengthening fin 19 between the first-layer H-shaped fin 14 and the area 11 adjacent to the heat source, the thermal energy received by the area 11 adjacent to the heat source can be conducted to the second-layer H-shaped fin 15 by heat conduction directly through the first-layer H-shaped fin 14 and the strengthening plate 18 or strengthening fin 19, thereby accelerating the thermal energy conduction speed (see FIG. 1B). The two-layer H-shaped fin structure including the strengthening plate 18 or strengthening fin 19 has a significantly increased thermal conduction area compared to the single-layer first-layer H-shaped fin 14, and can similarly effectively enhance the thermal convection effect when contacting the substance or material in the storage space 13 for heat exchange.

[0030] 1A , in order to enhance the thermal convection effect, a clear temperature gradient is formed between a portion 11 adjacent to the heat source and a portion 12 away from the heat source. To achieve this clear temperature gradient, the overall volume of the second-layer H-shaped fin 15 is designed to be larger than that of the first-layer H-shaped fin 14. In other words, the overall surface area of ​​the second-layer H-shaped fin 15 is also larger than that of the first-layer H-shaped fin 14. Therefore, the length of the first intermediate plate 143 of the first-layer H-shaped fin 14 must be shorter than the length of the second intermediate plate 153 of the second-layer H-shaped fin 15. This ensures that the overall volume and surface area of ​​the second-layer H-shaped fin 15 are larger than those of the first-layer H-shaped fin 14.

[0031] By connecting the first-layer H-shaped fins 14 to the connecting plate 16 of the second-layer H-shaped fins 15, the heat conduction path between the first-layer H-shaped fins 14 and the second-layer H-shaped fins 15 is limited to the single connecting plate 16, which facilitates the formation of a clear temperature gradient between the first-layer H-shaped fins 14 and the second-layer H-shaped fins 15. Furthermore, the second left fin 152 and the second right fin 151 of the second-layer H-shaped fins 15 are most preferably positioned outside the first left fin 142 and the first right fin 141 of the first-layer H-shaped fins 14. That is, the orthographic projection surfaces of the second left fin 152 and the second right fin 151 in the normal direction d of the heat source vicinity 11 are larger than the orthographic projection surfaces of the first left fin 142 and the first right fin 141 in the normal direction d of the heat source vicinity 11. As shown in FIG. 1A , this design facilitates the formation of a clear temperature gradient between the first-layer H-shaped fins 14 and the second-layer H-shaped fins 15. In other words, the present invention uses a variety of different means to create a distinct temperature gradient between a location 11 adjacent to the heat source and a location 12 away from the heat source.

[0032] 1A to 1D, the heat transfer structure 1 for improving the heat convection effect according to the present invention is a plate-like structure, i.e., the portion 11 adjacent to the heat source and the portion 12 away from the heat source are both flat metal plates, and the containing space 13 formed between them is a rectangular space surrounded by the two flat metal plates. However, the present invention is not limited to this, and the portion 11 adjacent to the heat source and the portion 12 away from the heat source may have different shapes according to actual needs, such as an arc, circle, concave, convex, arc, etc. Below, other embodiments of heat transfer structures with different shapes for improving the heat convection effect will be described.

[0033] Another embodiment of the present invention provides a heat transfer structure 2 for improving the heat convection effect (see FIGS. 2A and 2C). The outer shapes of the heat source-proximate portion 11 and the heat source-distant portion 12 are both modified to metal circular pipes. The heat transfer structure 2 includes an inner tube 21 similar to the heat source-proximate portion 11 and configured to receive thermal energy, an outer tube 22 similar to the heat source-distant portion 12 and configured relative to the inner tube 21 to form a receiving space 23 between the inner tube 21, the diameter of the inner tube 21 being smaller than that of the outer tube 22, the inner tube 21 being positioned within the outer tube 22, and the receiving space 23 formed between the outer tube 22 and the inner tube 21 being an annular space, and a plurality of H-shaped fin structures 27 installed in the receiving space 23 and arranged around the circumferential direction of the inner tube 21 within the annular space.

[0034] 2A, the H-shaped fin structure 27 in this embodiment includes a first-layer H-shaped fin 24, a connecting plate 26, and a second-layer H-shaped fin 25. The first-layer H-shaped fin 24 includes a first right fin 241 connected to the inner tube 21, a first left fin 242 connected to the inner tube 21 and disposed opposite the first right fin 241 on the left and right sides, and a first intermediate plate 243 extending in the circumferential direction of the inner tube 21 to the first left fin 242 and first right fin 241 connected on the left and right sides, thereby forming an arc shape. The second layer H-shaped fins 25 include a second right fin 251 connected to the outer tube 22, a second left fin 252 connected to the outer tube 22 and installed opposite the second right fin 251 on the left and right, and a second intermediate plate 253 extending circumferentially around the inner tube 21 to the second left fin 252 and the second right fin 251, which are connected on the left and right sides. A connecting plate 26 is connected to the first layer H-shaped fins 24 and the second layer H-shaped fins 25, and is located between the first layer H-shaped fins 24 and the second layer H-shaped fins 25.

[0035] In this embodiment, the outer tube 22 and the inner tube 21 are arranged concentrically, so that the outer tube 22 and the inner tube 21 collectively form a concentric tube, and six H-shaped fin structures 27 are radially arranged within the annular space of this concentric tube structure. Although the present invention is not limited thereto, in some embodiments, N H-shaped fin structures 27 are arranged within the annular space, and each of the N H-shaped fin structures 27 includes N first-layer H-shaped fins 24, N connecting plates 26, and N second-layer H-shaped fins 25, each of which respectively forms the N H-shaped fin structures 27, where N is a positive integer greater than 1. In some embodiments, the number of the N H-shaped fin structures 27 is between 2 and 9, and preferably between 3 and 6.

[0036] 2B is a partially enlarged view showing two adjacent H-shaped fin structures 27 (shown within the dashed circle in FIG. 2A ) in the heat transfer structure 2 that improves the thermal convection effect shown in FIG. 2A . Basically, each of the H-shaped fin structures 27 is the same size, and the fins on the left and right sides of each of the first-layer H-shaped fins 24 and second-layer H-shaped fins 25 of the H-shaped fin structure 27 are installed symmetrically with respect to the connecting plate 26. Therefore, since the included angle between the first right fin 241 of the first-layer H-shaped fin 24 and the connecting plate 26 is a first included angle θ1, the angle between the first left fin 242 and the connecting plate 26 is also a first included angle θ1. Since the included angle between the second right fin 251 of the second-layer H-shaped fin 25 and the connecting plate 26 is a second included angle θ2, the angle between the second left fin 252 and the connecting plate 26 is also a second included angle θ2.

[0037] 1B , the included angle between the first left fin 242 and the first right fin 241 of two adjacent first-layer H-shaped fins 24 is a third included angle θ3, which is equal to the circumferential angle 360 ​​degrees minus the included angle between the first right fin 241 and the first left fin 242 of the first-layer H-shaped fin 24 (i.e., the two first included angles θ1), multiplied by N (i.e., the six H-shaped fin structures 27), and then divided by N (i.e., the six gaps between the six H-shaped fin structures 27). The relationship therebetween is expressed as follows: (360°-2*θ1*N) / N=θ3, where θ1 is the first included angle, θ3 is the third included angle, and N is the quantity of the H-shaped fin structures 27.

[0038] 2B , the included angle between the second right fin 251 and the second left fin 252 of two adjacent second-layer H-shaped fins 25 is a third included angle θ4, which is equal to the circumferential angle 360 ​​degrees minus the included angle between the second right fin 251 and the second left fin 252 of the second-layer H-shaped fin 25 (i.e., the two second included angles θ2), multiplied by N (i.e., the six H-shaped fin structures 27), and then divided by N (i.e., the six gaps between the six H-shaped fin structures 27). The relationship therebetween is expressed as follows: (360°-2*θ2*N) / N=θ4, where θ2 is the second included angle, θ4 is the fourth included angle, and N is the quantity of the H-shaped fin structures 27.

[0039] In the above description of the high thermal convection effect, the overall volume and surface area of ​​the second-layer H-shaped fins 25 must be larger than those of the first-layer H-shaped fins 24. Therefore, the first included angle θ1 between the first right fin 241 of the first-layer H-shaped fins 24 and the connecting plate 26 is smaller than the second included angle θ2 between the second right fin 251 of the second-layer H-shaped fins 25 and the connecting plate 26. Similarly, the first included angle θ1 between the first left fin 242 of the first-layer H-shaped fins 24 and the connecting plate 26 is also smaller than the second included angle θ2 between the second left fin 252 of the second-layer H-shaped fins 25 and the connecting plate 26. Similarly, the third included angle θ3 between the first right fin 241 and the first left fin 242 of two adjacent first layer H-shaped fins 24 is larger than the fourth included angle θ4 between the second right fin 251 and the second left fin 252 of two adjacent second layer H-shaped fins 25.

[0040] In this embodiment, the length of the first right fin 241 is approximately equal to the length of the first left fin 242, the length of the first right fin 241 is approximately equal to the length of the second right fin 251, the length of the second right fin 251 is approximately equal to the length of the second left fin 252, the length of the first intermediate plate 243 is shorter than the length of the second intermediate plate 253, and the length of the connecting plate 26 is longer than the length of the first right fin 241. Furthermore, the first right fin 241 and the first left fin 242 of the first-layer H-shaped fin 24 extend radially from the inner tube 21 toward the outer tube 22 and into the accommodating space 23, and the second right fin 251 and the second left fin 252 of the second-layer H-shaped fin 25 extend radially from the outer tube 22 toward the inner tube 21 and into the accommodating space 23. The first intermediate plate 243 is extended along the circumferential direction of the inner tube 21, thereby connecting the left and right sides to the first left fin 242 and the first right fin 241, the second intermediate plate 253 is extended along the circumferential direction of the outer tube 22, thereby connecting the left and right sides to the second left fin 252 and the second right fin 251, and the connecting plate 26 is extended along the radial direction of the concentric tube, thereby connecting to the first intermediate plate 243 and the second intermediate plate 253.

[0041] FIG. 3 is a schematic diagram showing the cross-sectional structure of a heat storage device 3 according to another embodiment of the present invention. The heat transfer structure 1 for improving the heat convection effect described above is applied to this heat storage device 3. This heat storage device 3 includes the heat transfer structure 1 and a phase change material 31 installed in a storage space 13 between a portion 12 away from the heat source and a portion 11 adjacent to the heat source, and in contact with the first-layer H-shaped fins 14, a connecting plate 16, and a second-layer H-shaped fins 15. The phase change material 31 absorbs or releases a large amount of latent heat upon phase change. In this embodiment, this heat storage device 3 can be used to cool a graphics processing unit (GPU) G, achieving a heat dissipation effect by absorbing the thermal energy generated by the GPU G into the heat storage device 3. In other words, using this heat storage device 3 as a heat sink can prevent the device from overheating.

[0042] In some embodiments, the phase change material 31 includes organics (e.g., paraffins and non-paraffins), inorganics (e.g., salt hydrates, molten salts, and metal alloys), and eutectics (e.g., a mixture of two organics, two inorganics, or an organic and inorganic material). In this example, the phase change material 31 is paraffin, a fatty acid, or a salt hydrate.

[0043] 4 is a schematic diagram showing the cross-sectional structure of a heat storage device 4 according to another embodiment of the present invention. The heat transfer structure 2 for improving the thermal convection effect described above is applied to this heat storage device 4, which includes the heat transfer structure 2 and a phase change material 41 installed in the accommodating space 23 between the outer tube 22 and the inner tube 21 and in contact with the first layer H-shaped fins 24, the connecting plate 26, and the second layer H-shaped fins 25. The phase change material 41 absorbs or releases a large amount of latent heat when it undergoes a phase change.

[0044] To verify whether the H-shaped fins of the heat transfer structure of the present invention are effective in enhancing thermal convection, a heat flow simulation experiment is conducted on the H-shaped fin structure 27 of the heat transfer structure 2. For this, the business suite numerical simulation software ANSYS2022R2 Fluent is used to calculate the two-phase flow field during the melting process of a phase change material (PCM), and a conjugate heat transfer (CHT) simulation method is used to verify the effect of the H-shaped fin structure 27 in thermal energy storage.

[0045] 2A , a heat flow simulation experiment was conducted using a heat transfer structure 2 including six identical H-shaped fin structures 27 of the present invention. The radius of the inner tube 21 was 36.5 mm, the radius of the outer tube 22 was 95 mm, and the thickness of the inner tube 21 and outer tube 22 was 2 mm. The radius of the second intermediate plate 253 of the second layer of H-shaped fins 25 was 81 mm and the bending angle was the second included angle θ2. The radius of the first intermediate plate 243 of the first layer of H-shaped fins 24 was 21.5 mm and the bending angle was the first included angle θ1. The length of the connecting plate 26 was 30 mm, and the lengths of the first left fin 242, first right fin 241, second left fin 252, and second right fin 251 were each 25 mm. The above geometric parameters served as the basis for the simulation experiment. Aluminum was used as the material for the heat transfer structure 2, and the phase change material was a commercial product RT-42 manufactured by Rubitherm GmbH. RT-42 is a paraffin material that stores thermal energy as a phase change medium. The present invention utilizes computational fluid dynamics (CFD) software to rapidly and efficiently simulate and predict flow field dynamics. In the numerical simulation of the H-shaped fins of the heat transfer structure of the present invention, the key parameters affecting the thermal convection effect are primarily the change in fin thickness and the change in the bending angle between the second-layer H-shaped fins 25 and the first-layer H-shaped fins 24. The simulation results are detailed below.

[0046] First, referring to Figure 5, we compared the melting rates of three different fin thicknesses (1 mm, 2 mm, and 3 mm). The bending angle parameters were fixed, with the second included angle θ2 = 23° and the first included angle θ1 = 19°. Initially, the phase change material melted at similar rates in all three cases. However, after 200 seconds, the melting rates of the 1 mm and 2 mm cases began to decrease, indicating that their melting rates were slower than those of the 3 mm case. The 1 mm case had the poorest heat transfer performance due to its thin thickness. Therefore, its melting rate was also the slowest. The thin thickness limited the heat transfer rate and reduced the melting rate. In comparison, the 3 mm case had the fastest melting rate and a longer heat transfer distance due to its larger heat transfer surface area. Table 1 below demonstrates the phenomenon of the phase change material melting rate accelerating with increasing surface area.

[0047] JPEG0007817709000001.jpg28170

[0048] Next, we investigated how the second-layer H-shaped fin 25 and the first-layer H-shaped fin 24 affect the heat transfer of the thermal energy storage system and how the ratio of the bending angles between them affects the thermal convection effect. Two cases were designed. In the first case (case 1), as shown in Figure 6, the second included angle θ2 is maintained at a steady value of 23°, and the first included angle θ1 is varied between 15° and 28°. In the second case (case 2), as shown in Figure 7, the second included angle θ2 is maintained at a steady value of 19°, and the first included angle θ1 is varied between 12° and 25°. Simulations for both cases were performed using a fin structure with a thickness of 3 mm.

[0049] Referring to Figures 2B and 8, Figure 8 shows the flow vectors, temperature distribution (A), and liquid distribution (B) obtained by performing a numerical simulation on the fin structure shown in Figure 2B. In the three semi-confined convection regions (labeled 1, 2, and 3 in Figure 8) formed between the second-layer H-shaped fin 25 and the first-layer H-shaped fin 24, many convection groups can be observed from the velocity vectors in the figure, also known as Rayleigh-Bénard convection. This phenomenon occurs when the ratio of the second included angle θ2 to the first included angle θ1 is 1.32 (i.e., θ2 / θ1 = 1.32) and the time is 825 seconds. The temperature of the first-layer H-shaped fin 24 near the surface of the inner tube 21 is higher than that of the second-layer H-shaped fin 25. This radial temperature gradient forms multiple convection groups in the three semi-confined convection regions. After heating, the phase change material in the lower half of the fin generates buoyancy, lowering the temperature of the upper half of the fin, creating a cooling effect. This causes fluid movement, with the hotter, less dense fluid flowing upward along the inclined radial fin surface. The lower temperature in the upper half of the fin acts to cool the fluid, increasing its density and causing it to descend to the bottom, creating a unique convection mode. However, in other areas with lower temperatures and slower velocities, vortex reduction occurs, and heat is primarily transferred via conduction. Figure 8 (B) shows several blue regions, indicating that the solid phase change material has not yet melted and the flow velocity is zero.

[0050] Referring to Figure 9, the relationship between the change in bending angle and melting rate in Case 1 (Case 1) and Case 2 (Case 2) can be seen; detailed data are shown in Figures 6 and 7, respectively. In Case 1 (Case 1), the second included angle θ2 was 23°, and a fin structure with a ratio of 0.92 was used, resulting in a total melting time of 1,856 seconds. This indicates that the melting rate of the fin structure in Case 1 (Case 1) with a ratio of 0.92 was 5.3%, 0.32%, 0.27%, and 5.9%, respectively, faster than the melting rates of the other cases, compared to the remaining ratios of 0.82, 1, 1.21, and 1.53. In Case 2 (Case 2), the second included angle θ2 was 19°, and a fin structure with a ratio of 1.32 was used, resulting in a total melting time of 1,501 seconds. The melting rates of the fin structure with a ratio of 1.32 in case 2 (case 2) were 24%, 68.6%, 54.6%, and 60.7% faster than those of the other cases, respectively, compared with the remaining ratios of 1.21, 1, 0.84, and 0.68. Total melting time is generally proportional to the fin area, and this result indicates that a decrease in the PCM area results in an increase in the fin structure area. Therefore, this phenomenon explains the decrease in total melting time as the fin structure area increases. However, considering the ratios of 0.82 and 0.92 in case 1 (case 1) and the ratios of 1.21 and 1.32 in case 2 (case 2), an increase in the fin structure area does not necessarily decrease the total melting time. A shorter distance between two adjacent H-shaped fin structures creates unfavorable conditions for natural convection. Under these conditions, a smaller PCM area results in a longer total melting time. In the H-type fin structure, the fin structure design with a ratio of 1.32 in case 2 is advantageous for generating strong natural convection, effectively shortening the melting time required for the phase change material.

[0051] FIG. 10 is a bar graph showing the total ratios of total energy (Etotal), average power (Pm), and energy per unit mass (Em) for the first and second cases of the present invention. Total energy (Etotal) refers to the total energy stored in the phase change material (PCM) and H-type fins, which accounts for the total energy capacity of the system. Average power (Pm) is an indicator of melting performance and provides insight into the efficiency of the phase change process undergone by the PCM. Energy per unit mass (Em) is a valuable indicator used to evaluate the energy storage density of the H-type fin structure, quantifying the energy stored per unit mass of the system.

[0052] In this example, the total energy (Etotal) is the sum of the latent heat and the sensible heat, and the ratio of 0.68 for the fin structure in case 2 has the highest total energy (Etotal), which also has the largest surface area of ​​the phase change material when the phase change material is completely melted. The ratios for the other cases are 0.82, 0.92, 1, 1.21, 1.53, 1.32, 1, and 0.84, while the ratios for the other cases are 0.84 and 0.68, which are 3.4%, 3.2%, 0.28%, 0.23%, 1.2%, 6%, 0.22%, and 0.19%, respectively.

[0053] In this example, the average power (Pm) is the ratio of total energy (Etotal) to total melting time, which indicates an improvement in melting. The average power (Pm) is significantly affected by the placement of the H-type fin. When the ratio is 1.32, the first case (case 1) and the second case (case 2) show the highest average power with the other ratios of 0.82, 0.92, 1, 1.53, 1.21, 1, 0.84, and 0.68, respectively, with differences of 27%, 20%, 19%, 24.9%, 17%, 59%, 46%, and 51% compared to the others.

[0054] In this example, the energy per unit mass (Em) is used to represent the energy per unit mass, which is primarily limited by the material properties and the volume of the PCM and aluminum in the heat transfer process. In the context of solid fins made of PCM and aluminum, solid aluminum fins occupy less space and have a higher density than PCM, but the total mass of the fin structure cannot be ignored. For example, the unit mass energy (Em) of Case 1 and Case 2 is not the same. The H-type fin structure and the ratio of PCM are different, which indirectly affect the final determination of the temperature distribution per unit mass. Therefore, these structural factors must be taken into account when evaluating the heat transfer process of the current H-type fin structure.

[0055] Based on the above content and simulation results, the present invention has the following technical features. 1. Increasing the fin area reduces the melting time of the phase change material (PCM). A 3mm fin thickness reduces the total melting time by 88% compared to the H-type fin structure with a 1mm fin thickness. 2. In conventional radially arranged H-type fin structures, natural convection plays an important role in heat transfer. Because the temperature of the outer layer of the H-type fin structure is lower than that of the inner layer near the heat source, a temperature difference occurs, creating an environment favorable for the formation of natural convection. 3. Rayleigh-Benard convection is observed in the concentric tubes of the conventional H-type fin structure, which generates more flow-diverting cells, helping to shorten the total melting time and improve melting performance. 4. The second included angle θ2 is larger than the first included angle θ1, which helps to form natural convection, allowing the heat convection to flow over more space, helping to shorten the melting rate of the phase change material (PCM), and improving the overall heat transfer efficiency. 5. By changing the two bending angles of the H-type fin structure, the area and volume of the PCM are changed. This change directly changes the total energy (Etotal) stored within the concentric tubes of the H-type fin structure. A PCM with a larger area and volume, with a ratio of 0.68, allows the PCM to store a larger amount of thermal energy. 6. The change in the bending angle of the second included angle θ2 and the first included angle θ1 is the key to affect the mean output power (Pm) and the natural convection melting time of the phase change material (PCM). The second case (case 2) has the highest mean output power (Pm) due to its outstanding heat transfer coefficient with a ratio of 1.32.

[0056] Based on the above findings, the H-type fin structure and phase change material (PCM) of the present invention can be applied to latent thermal energy storage systems (LHTES). However, to achieve improved heat transfer efficiency or increased total energy capacity, the spatial arrangement of the H-type fin structure must be properly designed. If the primary goal is to maximize total energy storage, a ratio of 1.21 is optimal. Conversely, if the goal is to obtain the highest total energy per unit mass, a ratio of 1 in case 2 (case 2) is the best design choice. If the shortest total melting time is required, a ratio of 1.32 in case 2 (case 2) is the best design choice. In summary, a ratio between 1 and 1.32 is the preferred design choice, and the arrangement design of the H-type fin structure plays a key role in latent thermal energy storage systems (LHTES) with phase change materials.

[0057] In conclusion, the heat transfer structure for improving the thermal convection effect of the present invention uses a specially designed H-shaped fin structure to increase the contact area for heat exchange, and the annular arrangement of multiple H-shaped fins within the concentric tube effectively generates strong natural convection, which rapidly melts the phase change material, thereby solving the problem of slow natural convection and low heating efficiency for the phase change material in conventional latent heat storage systems.

[0058] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention. [Explanation of symbols]

[0059] 1 Heat transfer structure 11 Areas near heat sources 12 Away from heat sources 13 Containment Space 14 First layer H-shaped fin 141 First Right Fin 141c 1st right fin 141d 1st right fin 142 1st left fin 142c 1st left fin 142d 1st left fin 143 First intermediate plate 143a 1st intermediate plate 143c 1st intermediate plate 143d 1st intermediate plate 15 Second layer H-shaped fin 151 Second Right Fin 151c 2nd right fin 151d 2nd right fin 152 Second left fin 152c 2nd left fin 152d 2nd left fin 153 Second intermediate plate 153a 2nd intermediate plate 153b 2nd intermediate plate 153c 2nd intermediate plate 153d Second intermediate plate 16 Connection plate 16a Connection plate 16d Connection plate 17 H-type fin structure 18 Reinforcement plate 19 Reinforced fins 21 Inner tube 22 outer tube 23 Containment Space 24 First layer H-shaped fin 241 First Right Fin 242 1st left fin 243 First intermediate plate 25 Second layer H-shaped fin 251 Second Right Fin 252 Second left fin 253 Second intermediate plate 26 Connection plate 27 H-type fin structure θ1 1st included angle θ2 2nd included angle θ3 3rd included angle θ4 4th included angle 3 Heat storage device 31 Phase change materials 4 Heat storage device 41 Phase change materials d Normal direction S heat source G graphics processor

Claims

1. a location adjacent the heat source for receiving thermal energy from the heat source; a portion away from the heat source, the portion being provided adjacent to the heat source and forming an accommodation space between the portion and the adjacent portion; a first layer H-shaped fin installed in the accommodation space and adjacent to and connected to a portion adjacent to the heat source; a second-layer H-shaped fin disposed in the accommodation space relative to the first-layer H-shaped fin, the second-layer H-shaped fin being adjacent to a portion remote from the heat source and connected to a portion remote from the heat source, and the second-layer H-shaped fin being connected to the first-layer H-shaped fin to form an H-shaped fin structure; a connecting plate connected to the first layer H-shaped fins and the second layer H-shaped fins and positioned between the first layer H-shaped fins and the second layer H-shaped fins, wherein the first layer H-shaped fins, the connecting plate, and the second layer H-shaped fins collectively form the H-shaped fin structure; Equipped with The first layer H-shaped fin is a first right fin connected to a portion adjacent to the heat source; a first left fin connected to a location adjacent to the heat source and disposed opposite to the first right fin; a first intermediate plate connected to the first left fin and the first right fin, The second layer H-shaped fin is a second right fin connected to a portion away from the heat source; a second left fin connected to a location away from the heat source and disposed opposite the second right fin; a second intermediate plate connected to the second left fin and the second right fin, A heat transfer structure for improving a thermal convection effect, characterized in that the length of the first intermediate plate is shorter than the length of the second intermediate plate.

2. At least one first reinforcing plate connected to the first intermediate plate and the portion of the first layer H-shaped fin adjacent to the heat source and positioned between the first intermediate plate and the portion of the first layer H-shaped fin adjacent to the heat source; and / or The heat transfer structure for improving the thermal convection effect described in claim 1, further comprising at least one second reinforcing plate connected to the second intermediate plate and / or the portion of the second layer H-shaped fin away from the heat source and positioned between the second intermediate plate and the portion away from the heat source.

3. A heat transfer structure that improves the thermal convection effect described in claim 1, characterized in that the orthogonal projection surfaces of the second left fin and the second right fin in the normal direction of the vicinity of the heat source are larger than the orthogonal projection surfaces of the first left fin and the first right fin in the normal direction of the vicinity of the heat source.

4. 2. The heat transfer structure for improving thermal convection effect according to claim 1, wherein a first included angle between the first right fin of the first layer of H-shaped fins and the connecting plate is smaller than a second included angle between the second right fin of the second layer of H-shaped fins and the connecting plate.

5. 5. The heat transfer structure for improving thermal convection effect according to claim 1, wherein the portion adjacent to the heat source is an inner tube and the portion away from the heat source is an outer tube, the inner tube is disposed within the outer tube, an annular space is formed between the outer tube and the inner tube, the H-shaped fin structure is disposed in the annular space, and the outer tube and the inner tube are disposed so as to form concentric circles with the same axis, and the outer tube and the inner tube collectively form a concentric pipe.

6. 6. The heat transfer structure for improving thermal convection effect according to claim 5, further comprising: N first layer H-shaped fins, N connecting plates, and N second layer H-shaped fins, each forming one of the N H-shaped fin structures, where N is a positive integer greater than 1.

7. 7. The heat transfer structure for improving thermal convection effect according to claim 6, wherein a third included angle between the first right fin and the first left fin of two adjacent first-layer H-shaped fins is greater than a fourth included angle between the second right fin and the second left fin of two adjacent second-layer H-shaped fins.

8. The heat transfer structure according to claim 7; A heat storage device characterized by comprising: a phase change material that is installed in the storage space between a location away from the heat source and a location close to the heat source, and that is in contact with the first layer H-shaped fins and the second layer H-shaped fins.

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