A three-arc cross-tank composite graphite phase change thermal storage structure

Abstract

The present invention provides a three-arc cross-tank composite graphite phase-change thermal storage structure. Through the special three-arc structure of the thermal storage unit combined with a specific splicing method, PCM is placed in the thermal storage unit in multiple areas, and the crescent-shaped gaps formed between two adjacent thermal storage units serve as HTF flow channels. This increases the contact area and creates turbulence in the flow channels, resulting in higher heat exchange efficiency and more space conservation. The use of a graphite material superimposed with a dense coating enables the thermal storage unit to be used in harsh environments, including those with corrosive PCM and HTF, and in a higher heat storage temperature range. This solves technical problems existing in the prior art, such as poor heat exchange efficiency, easy corrosion and scaling, and affected heat transfer efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of phase-change heat storage heat exchangers, and in particular to a three-arc cross-tank composite graphite phase-change heat storage structure. Background Art

[0002] Phase-change energy storage offers the advantages of high energy storage density and near-constant-temperature heat storage and release. Currently, mainstream phase-change heat storage devices are roughly divided into three categories: shell-and-tube, packed-bed, and plate. The corresponding thermal storage units used are, respectively, tube-in-tube, capsule, and plate.

[0003] Chinese patent CN202210689119.9 discloses a shell and tube phase change heat storage heat exchanger that utilizes internal and external fractal fins to enhance heat exchange; wherein, the heat exchange tube includes a hot fluid heat exchange channel, a cold fluid heat exchange channel and a plurality of internal and external fractal fins 1 and internal and external fractal fins 2 that are evenly distributed and staggered along the circumference; the structures of the internal and external fractal fins 1 and the internal and external fractal fins 2 are exactly the same, both including one-piece first-level outer fins, second-level middle fins and third-level inner fins, and the internal and external fractal fins 1 and the internal and external fractal fins 2 face opposite directions and are staggered along the circumference.

[0004] However, the existing circular tube-in-tube thermal storage unit places a phase change thermal storage material (PCM) in the interlayer between the outer tube and the inner tube, with a heat transfer fluid (HTF) passing through the inner tube. Since the HTF and PCM cannot form strong convection, the heat transfer efficiency is low. Even if fins are added to increase the heat transfer area, the heat transfer efficiency is still unsatisfactory. Moreover, when the PCM itself is corrosive, the fins are prone to scaling and corrosion, causing the joints between the fins and the outer wall of the inner tube to break, thus losing the ability to improve heat transfer efficiency. Summary of the Invention

[0005] The present invention addresses the shortcomings of the prior art by providing a three-arc cross-tank composite graphite phase-change thermal storage structure. This structure utilizes thermal storage units with a special three-arc structure combined with a specific splicing method. PCM is placed within the thermal storage units in multiple zones, and the crescent-shaped gaps between adjacent thermal storage units serve as HTF flow channels. This increases the contact area and creates turbulent flow within the flow channels, resulting in higher heat exchange efficiency and space conservation. Furthermore, the use of a graphite material superimposed with a dense coating enables the thermal storage unit to be used in harsh environments, including those subject to the corrosive properties of PCM and HTF, and in a higher heat storage temperature range. This addresses the technical issues of the prior art, such as poor heat exchange efficiency, prone to corrosion and scaling, and reduced heat transfer efficiency.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A three-arc cross-tank composite graphite phase-change thermal storage structure comprises at least two interconnected thermal storage units, wherein the outer wall surfaces of the thermal storage units are formed by a circumferential staggered array of a plurality of first and second arc surfaces. The center of the first arc surface is the center of the tank body and the arc surface curves toward the center of the tank body, while the arc surface of the second arc surface curves away from the center of the tank body. Two adjacent thermal storage units are spliced ​​together in such a way that the first arc surface of one thermal storage unit and the second arc surface of the other thermal storage unit are connected at the arc vertex as the intersection point, thereby forming a crescent-shaped gap between the two adjacent thermal storage units, which serves as an HTF flow channel.

[0008] Preferably, three groups of the first arc surfaces and three groups of the second arc surfaces are provided, and the arc angle of the first arc surfaces is 60°.

[0009] Preferably, a plurality of the heat storage units are spliced ​​in a ring array with one heat storage unit as the center, and each first arc surface and second arc surface of the heat storage unit located in the inner circle is spliced ​​with one heat storage unit.

[0010] The heat storage units are spliced ​​in the following manner: with one heat storage unit as the center, several heat storage units are spliced ​​in a circle around the circumference of the heat storage unit as the first circle, and then several heat storage units are spliced ​​in a circle around the circumference of the first circle of heat storage units as the second circle, and so on; the first circle has a total of 6 heat storage units, the second circle has a total of 12, and so on.

[0011] As a preferred embodiment, with one heat storage unit as the center, its outer annular array is spliced ​​with two circles of heat storage units.

[0012] Preferably, adjacent heat storage units are bonded and fixed at the joint points by graphite glue.

[0013] Preferably, the device further comprises: an outer shell, at least two heat storage units spliced ​​together are installed in the outer shell, a support portion is provided at both ends of the heat storage unit in the length direction of the outer shell, and the two support portions support and limit the heat storage unit in the length direction; the heat storage unit in the outer shell is provided in at least one layer along the length direction.

[0014] Preferably, the main body of the outer shell for mounting the heat storage unit is cylindrical and the inner wall thereof is in contact with the first curved surface of the heat storage unit.

[0015] Preferably, the heat storage unit comprises a tank body and a sealing cover having the same cross-sectional shape and matching sealing covers.

[0016] Preferably, main ribs and secondary ribs are further provided in the tank body, wherein a main rib is connected between each of the first curved surfaces and the center of the tank body, and a secondary rib is connected between each of the main ribs and the two second curved surfaces on both sides thereof. The main ribs and secondary ribs divide the tank body into nine areas for placing PCM.

[0017] Preferably, the main rib is connected to the arc midpoint of the first arc surface.

[0018] Preferably, the secondary reinforcement is connected between the midpoint of the main reinforcement and the one-third dividing point of the second arc surface.

[0019] Preferably, the heat storage unit is made of graphite material and is coated with a ceramic coating on its inner and outer surfaces; the sealing cover and the tank body are sealed by coating with the ceramic coating.

[0020] Preferably, a stepped sealing structure is adopted between the sealing cover and the tank body.

[0021] Preferably, the height of the tank body is 100~500mm, the wall thickness is 2~15mm, the diameter of the first arc surface is 20~200mm, the arc angle of the second arc surface is 50~150°, the thickness of the sealing cover is 10~50mm, and the thickness of the ceramic coating is 10~100μm.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention combines the special three-arc structure of the heat storage unit with a specific splicing method between the heat storage units. The heat storage unit is formed by a plurality of first arc surfaces and second arc surfaces arranged in a staggered array along the circumference to form a three-arc structure, in which PCM is placed. The first arc surface and the second arc surface of adjacent heat storage units are spliced ​​at the arc vertex as the intersection to form a crescent-shaped HTF flow channel, thereby forming a method in which PCM is placed in the tank and HTF flows in the gap between the tanks. Compared with the traditional circular shell and tube heat storage unit, this heat exchange structure has a larger contact area and forms turbulent flow in the flow channel, which has higher heat exchange efficiency and saves more space.

[0024] (2) In terms of material selection, the present invention uses a graphite material superimposed with a dense coating, so that the thermal storage unit can be used in harsh environments, including the corrosiveness of PCM, the corrosiveness of HTF, and a higher thermal storage temperature range;

[0025] (3) The present invention divides the space inside the tank into multiple areas by arranging main ribs and secondary ribs in the heat storage unit, and further improves the heat exchange efficiency by increasing the heat exchange area and adjusting the uniformity of the heat transfer path;

[0026] (4) The heat storage structure of the present invention forms a crescent-shaped HTF flow channel between adjacent spliced ​​heat storage units, which reduces the short-flow escape of HTF and uniformly controls the flow rate and direction of HTF fluid, thereby adjusting the flow field of HTF and increasing the heat exchange area, thereby improving the heat exchange efficiency; avoiding the expansion and overflow of PCM after heating, and reducing the direct contact between PCM and HTF. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 for Figure 1 Schematic diagram of the structure after removing the outer shell;

[0029] Figure 3 This is a front view of the structure of the heat storage unit in the present invention;

[0030] Figure 4 This is a front view of the splicing structure of the heat storage unit and the outer shell in the present invention;

[0031] Figure 5 for Figure 1 Front view of

[0032] Figure 6 Schematic diagram of the structure of the heat storage unit in the present invention;

[0033] Figure 7 It is a structural schematic diagram of the tank body in the present invention;

[0034] Figure 8 for Figure 7 Front view of

[0035] Figure 9 Schematic diagram of the structure of the sealing cover of the present invention;

[0036] Figure 10 This is the temperature field distribution diagram of the conventional circular thermal storage unit when exchanging heat for 20 minutes;

[0037] Figure 11 This is the temperature field distribution diagram of the heat storage unit in the present invention when exchanging heat for 20 minutes (without primary and secondary ribs);

[0038] Figure 12 This is the temperature field distribution diagram of the heat storage unit in the present invention when the heat is exchanged for 19 minutes (no primary and secondary ribs are set);

[0039] Figure 13 This is the temperature field distribution diagram of the heat storage unit in the present invention when exchanging heat for 19 minutes (with main reinforcement);

[0040] Figure 14 This is the temperature field distribution diagram of the heat storage unit in the present invention when exchanging heat for 15 minutes (primary and secondary ribs are set);

[0041] Figure 15 This is the temperature field distribution diagram of a conventional circular thermal storage unit during 19 minutes of heat exchange (primary and secondary ribs are set). DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0044] Example 1

[0045] like Figure 2-Figure 4 As shown, a three-arc cross-tank composite graphite phase-change thermal storage structure comprises: at least two interconnected thermal storage units I, wherein the outer wall surface of each thermal storage unit I is formed by a plurality of first arc surfaces 11 and second arc surfaces 12 arranged in a staggered array along a circumference, wherein the center of the first arc surface 11 is the center of the tank body 1 and the arc surface curves toward the center of the tank body 1, and the arc surface of the second arc surface 12 curves away from the center of the tank body 1; the two adjacent thermal storage units I are connected in such a way that the first arc surface 11 of one thermal storage unit I and the second arc surface 12 of the other thermal storage unit I are connected at the arc vertex as the intersection point, thereby forming a crescent-shaped gap between the two adjacent thermal storage units I, which serves as the HTF flow channel 5.

[0046] In this embodiment, the unique three-arc structure of thermal storage unit I, combined with the specific splicing method between thermal storage units I, creates a method in which PCM is placed within the tank of thermal storage unit I and HTF flows through the splicing gaps between thermal storage units I. Compared with traditional circular shell-and-tube thermal storage units, this heat exchange structure has a larger contact area and creates turbulent flow within the flow channel. Specifically, by reducing the gaps between each heat exchange unit, the flow rate is increased. The crescent-shaped HTF flow channel 5 has a relatively irregular cross-section. When the fluid passes through, due to the flow rate and cross-sectional irregularities, a turbulent state is formed. This increases the flow resistance while improving the heat exchange efficiency and saving space.

[0047] Preferably, adjacent heat storage units I are bonded and fixed at the joint points by graphite glue.

[0048] When assembling the heat storage structure of this embodiment, the heat storage unit I is placed vertically for assembly, and the crescent-shaped HTF flow channel 5 is positioned using a plug gauge, which is then fixed with graphite glue and then the plug gauge is removed.

[0049] As a preference, Figure 1-Figure 2 As shown, it also includes: an outer shell II, at least two mutually spliced ​​heat storage units I are installed in the outer shell II, and a support part 6 is provided at both ends of the heat storage unit I in the length direction in the outer shell II, and the two support parts 6 support and limit the heat storage unit I in the length direction.

[0050] Preferably, the heat storage unit I in the outer shell II is provided with at least one layer along the length direction.

[0051] As a preferred embodiment, in this embodiment, Figure 2 As shown, the heat storage unit I is provided with three layers in the outer shell II.

[0052] Example 2

[0053] The same or corresponding components in this embodiment are marked with the same reference numerals as those in the above embodiment. For the sake of simplicity, only the differences from the above embodiment are described below. The differences between this embodiment and the above embodiment are:

[0054] As a preference, Figure 3 As shown, three groups of the first arc surface 11 and the second arc surface 12 are provided, and the arc angle of the first arc surface 11 is 60°.

[0055] As a supplementary explanation, the outer wall shape of the heat storage unit I is a cross-sectional shape obtained by cross-cutting three equal arcs, namely the second arc surface 12 and the circular base, and the arc remaining after the circular base is cut off is the first arc surface 11.

[0056] When at least two of the heat storage units I are connected, Figure 4 As shown, the directions of the heat storage units I are the same, and the same direction means that Figure 3 As shown, each heat storage unit is arranged with one of the first arc surfaces 11 facing upward.

[0057] Example 3

[0058] The same or corresponding components in this embodiment are marked with the same reference numerals as those in the above embodiment. For the sake of simplicity, only the differences from the above embodiment are described below. The differences between this embodiment and the above embodiment are:

[0059] As a preference, Figure 4 As shown, several of the heat storage units I are spliced ​​in a ring array with one heat storage unit I as the center, and each first arc surface 11 and second arc surface 12 of the heat storage unit I located in the inner circle is spliced ​​with one heat storage unit I.

[0060] As a supplementary explanation, the splicing method of several of the heat storage units I is: with one heat storage unit I as the center, several heat storage units I are spliced ​​around the circumference of the heat storage unit I as the first circle, and then several heat storage units I are spliced ​​around the circumference of the first circle of heat storage units I as the second circle, and so on; there are 6 heat storage units I in the first circle, 12 in the second circle, and so on.

[0061] As a preferred implementation, the heat storage structure in this embodiment is centered on a heat storage unit I, and its outer annular array is spliced ​​with two circles of heat storage units I.

[0062] Preferably, to match the heat storage unit I spliced ​​in an annular array, the outer shell II is used to install the main body of the heat storage unit I, which is set to be cylindrical and its inner wall is in contact with the first arc surface 11 of the heat storage unit I.

[0063] Example 4

[0064] The same or corresponding components in this embodiment are marked with the same reference numerals as those in the above embodiment. For the sake of simplicity, only the differences from the above embodiment are described below. The differences between this embodiment and the above embodiment are:

[0065] As a preference, Figure 6 As shown, the heat storage unit I includes a tank body 1 and a sealing cover 2 with the same cross-sectional shape and matching sealing cover.

[0066] As a preference, Figure 7-Figure 8As shown, main ribs 3 and secondary ribs 4 are further provided in the tank body 1. A main rib 3 is connected between each first curved surface 11 and the center of the tank body 1, and a secondary rib 4 is connected between each main rib 3 and the two second curved surfaces 12 on both sides thereof. The main ribs 3 and secondary ribs 4 divide the tank body 1 into nine areas for placing PCM.

[0067] In this embodiment, the space inside the tank body 1 is divided into multiple areas by providing main ribs 3 and secondary ribs 4 in the heat storage unit I, and the heat exchange efficiency is further improved by increasing the heat exchange area and adjusting the uniformity of the heat transfer path.

[0068] Specifically, the thermal conductivity of the phase change thermal storage material is low, while the thermal storage unit I, as a modified graphite material, has a relatively high thermal conductivity. Through the arrangement of primary and secondary ribs, the heat on the outer surface of the thermal storage unit I can be quickly transferred to the center of the phase change thermal storage material along the path of the primary and secondary ribs, rather than relying entirely on the phase change thermal storage material itself to transfer heat to the center. The primary and secondary ribs are equivalent to increasing the heat exchange area between the thermal storage unit I and the phase change thermal storage material.

[0069] Preferably, the main rib 3 is connected to the arc midpoint of the first arc surface 11 .

[0070] Preferably, the secondary rib 4 is connected and arranged between the midpoint of the main rib 3 and the one-third dividing point of the second arc surface 12 .

[0071] Preferably, a stepped sealing structure is adopted between the sealing cover 2 and the tank body 1 .

[0072] like Figure 9 As shown, in this embodiment, as a preferred implementation, the bottom surface of the sealing cover 2 has a boss 21, the outer diameter of the boss 21 is slightly adapted to the inner diameter of the tank body 1, and the tank body 1 is matched with a groove that is adapted to the shape and size of the boss 21. Therefore, when the sealing cover 2 is covered on the tank body 1, the boss 21 extends into the tank body 1 and cooperates with the groove, thereby realizing a stepped multi-level seal between the two.

[0073] Preferably, the height of the tank body 1 is 100-500 mm, the wall thickness is 2-15 mm, the diameter of the first arc surface 11 is 20-200 mm, the arc angle of the second arc surface 12 is 50-150°, and the thickness of the sealing cover 2 is 10-50 mm.

[0074] Example 5

[0075] The same or corresponding components in this embodiment are marked with the same reference numerals as those in the above embodiment. For the sake of simplicity, only the differences from the above embodiment are described below. The differences between this embodiment and the above embodiment are:

[0076] Preferably, the heat storage unit I is made of graphite material and is coated with a ceramic coating on its inner and outer surfaces.

[0077] Preferably, the sealing cover 2 and the tank body 1 are sealed by coating with a ceramic coating.

[0078] Preferably, the thickness of the ceramic coating is 10-100 μm.

[0079] It should be noted that the coating process involves spraying a precisely proportioned ceramic coating and then sintering it. During the sintering process, the coating evaporates at the seal between the sealing cap 2 and the tank body 1 and then adheres to the surface of the thermal storage unit, connecting with the upper and lower parts to form a dense ceramic coating. This means that the ceramic coating at the gap will connect with the ceramic coatings on the sealing cap 2 and the tank body 1, forming a single, dense ceramic coating that envelops the gap and seals it.

[0080] As a preferred embodiment, the ceramic coating is specifically a silicon carbide coating.

[0081] In terms of material selection, this embodiment uses a graphite material superimposed with a dense coating, so that the thermal storage unit I can be used in harsh environments, including the corrosiveness of PCM, the corrosiveness of HTF, and a higher thermal storage temperature range. It is resistant to high temperatures, corrosion, and is impermeable, and its applicable temperature range is -100~1500℃.

[0082] The three-arc cross-tank composite graphite phase-change thermal storage structure of the present invention forms crescent-shaped HTF flow channels between adjacent spliced ​​thermal storage units, reducing short-flow escape of HTF and evenly controlling the flow rate and direction of the HTF fluid, thereby adjusting the HTF flow field and increasing the heat exchange area, improving heat exchange efficiency. It also prevents the PCM from expanding and overflowing after being heated, reducing direct contact between the PCM and HTF.

[0083] As a supplementary explanation, compared to the gap formed by the tangent connection of four circular thermal storage units, the crescent-shaped HTF flow channel 5 of the present invention is narrower and has a smaller area. The narrowness increases the effective specific heat exchange area of ​​the HTF in contact with thermal storage unit I, while the smaller area reduces the rate of HTF escaping without heat exchange. The PCM expands due to heat and overflows, thus contacting the HTF, is prevented by sealing the thermal storage unit I with a lid.

[0084] like Figure 10 As shown in the figure, the unit calculation model of the conventional circular heat storage unit is as follows: the four areas at the four corners of the outer tangent square are HTF circulation areas. Under the supply of 550K HTF heat source, it can be seen that most of the central area is still around 400K after 20 minutes;

[0085] And as Figure 11As shown, the three-arc heat storage unit in this embodiment, due to its shape and layout characteristics, can pass through the circulation area of ​​the crescent-shaped HTF and, under the same 550K heat source, achieve isothermal contact with the HTF within 20 minutes. It can be seen that the three-arc shape has a significant effect on improving the heat exchange efficiency. Figure 12 As shown in Figure 1, at 19 minutes, it can be seen that there is an area at the centroid of the thermal storage unit that is still around 500K and has not reached the temperature of 550K. After the main reinforcement is set inside the thermal storage unit, as shown in Figure 1, Figure 13 As shown in Figure 1, at 19 minutes, the internal centroid has reached 550K. It can be seen that the internal main reinforcement 3 can further improve the heat transfer efficiency. When the internal secondary reinforcement 4 is also set, as shown in Figure 1, the internal centroid has reached 550K. Figure 14 As shown in the figure, it only takes 15 minutes to achieve a PCM temperature of 550K inside the entire thermal storage unit. This shows that adding 3 main ribs and 4 secondary ribs can further greatly improve the heat exchange efficiency (by 25%).

[0086] However, this form of adding 3 main ribs and 4 secondary ribs needs to be coordinated with a special shape, that is, it needs to be coordinated with the three-arc tank body, specifically, as described above. Setting up primary and secondary ribs can further improve the heat exchange efficiency. The heat exchange process can be decomposed into process (1): heat exchange between HTF and heat exchange unit, process (2): heat exchange between heat exchange unit and PCM; primary and secondary ribs are equivalent to increasing the heat exchange area of ​​process (2) and constructing a fast heat transfer guide. Compared with the circular section, the guiding effect of the primary and secondary ribs of the three-arc section is more obvious, more targeted, and it is easier to divide it into equal-sized areas. Since the circular section has a smaller specific heat exchange area in process (1), more primary and secondary ribs are required for the heat transfer path in process (2). As Figure 15 As shown in the figure, if it is still placed in the circular thermal storage unit, although there is an improvement, the PCM still does not reach 550K at 19 minutes, and it takes 33 minutes to reach 550K. Therefore, the efficiency improvement is still not comparable to that of the three-arc thermal storage unit.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A three-arc cross-tank composite graphite phase change thermal storage structure, characterized in that: include: At least two heat storage units (I) spliced ​​together, wherein the outer wall surface of the heat storage unit (I) is a shape formed by a plurality of first arc surfaces (11) and second arc surfaces (12) arranged in a staggered array along a circumference, wherein the center of the first arc surface (11) is the center of the tank body (1) and the arc surface is curved toward the center of the tank body (1), and the arc surface of the second arc surface (12) is curved away from the center of the tank body (1); The splicing method of two adjacent heat storage units (I) is that the first arc surface (11) of one heat storage unit (I) is connected to the second arc surface (12) of the other heat storage unit (I) with the arc vertex as the intersection point, thereby forming a crescent-shaped gap between the two adjacent heat storage units (I), and the gap serves as an HTF flow channel (5).

2. The three-arc cross-tank composite graphite phase change thermal storage structure according to claim 1, characterized in that: Three groups of the first arc surface (11) and the second arc surface (12) are provided respectively, and the arc angle of the first arc surface (11) is 60°.

3. The three-arc cross-tank composite graphite phase change thermal storage structure according to claim 1, characterized in that: A plurality of the heat storage units (I) are spliced ​​in a ring array with one heat storage unit (I) as the center, and each first arc surface (11) and second arc surface (12) of the heat storage unit (I) located in the inner circle is spliced ​​with one heat storage unit (I).

4. A three-arc cross-tank composite graphite phase change thermal storage structure according to any one of claims 1 to 3, characterized in that: Adjacent heat storage units (I) are bonded and fixed at the joints by graphite glue.

5. A three-arc cross-tank composite graphite phase change thermal storage structure according to any one of claims 1 to 3, characterized in that: Also includes: An outer shell (II) is provided, wherein at least two mutually connected heat storage units (I) are installed in the outer shell (II), and a support portion (6) is provided at both ends of the heat storage unit (I) in the length direction in the outer shell (II), and the two support portions (6) support and limit the heat storage unit (I) in the length direction; and the heat storage unit (I) in the outer shell (II) is provided in at least one layer along the length direction.

6. The three-arc cross-tank composite graphite phase change thermal storage structure according to claim 5, characterized in that: The main body of the outer shell (II) for mounting the heat storage unit (I) is cylindrical, and its inner wall is in contact with the first arc surface (11) of the heat storage unit (I).

7. A three-arc cross-tank composite graphite phase change thermal storage structure according to any one of claims 1 to 3, characterized in that: The heat storage unit (I) comprises a tank body (1) and a sealing cover (2) having the same cross-sectional shape and matching sealing covers.

8. The three-arc cross-tank composite graphite phase change thermal storage structure according to claim 7, characterized in that: The tank body (1) is further provided with a main rib (3) and a secondary rib (4). A main rib (3) is connected between each of the first arc surfaces (11) and the center of the tank body (1). A secondary rib (4) is connected between each of the main ribs (3) and the two second arc surfaces (12) on both sides thereof. The main ribs (3) and the secondary ribs (4) divide the tank body (1) into nine areas for placing PCM.

9. The three-arc cross-tank composite graphite phase change thermal storage structure according to claim 7, characterized in that: The heat storage unit (I) is made of graphite material and is coated with a ceramic coating on its inner and outer surfaces; the sealing cover (2) and the tank body (1) are sealed by coating with the ceramic coating.

10. The three-arc cross-tank composite graphite phase change thermal storage structure according to claim 7, characterized in that: The height of the tank body (1) is 100-500 mm, the wall thickness is 2-15 mm, the diameter of the first arc surface (11) is 20-200 mm, the arc angle of the second arc surface (12) is 50-150°, the thickness of the sealing cover (2) is 10-50 mm, and the thickness of the ceramic coating is 10-100 μm.

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