Three-arc crossed tank type composite graphite phase change heat storage structure

Abstract

According to the three-arc crossed tank type composite graphite phase change heat storage structure, heat storage units of a special three-arc structure are combined with a specific splicing mode, PCM is placed in the heat storage units of multiple areas, a crescent gap formed between every two adjacent heat storage units serves as an HTF flow channel, the contact area is larger, turbulent flow is formed in the flow channels, and the heat storage efficiency is improved. The heat storage unit is higher in heat exchange efficiency, more space is saved, and the heat storage unit can be applied to severe environments including PCM corrosivity, HTF corrosivity and a higher heat storage temperature interval due to the fact that the graphite material is overlaid and coated with the compact coating. The technical problems that in the prior art, heat exchange efficiency is not ideal, corrosion and scaling are prone to occurring, and heat transfer efficiency is affected are solved.

Description

Technical Field

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

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

[0003] Chinese Patent CN202210689119.9 discloses a shell-and-tube type phase change heat storage heat exchanger that enhances heat transfer using internal and external fractal fins; 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 one and internal and external fractal fins two that are circumferentially evenly distributed and staggered; the structures of the internal and external fractal fins one and the internal and external fractal fins two are exactly the same, and both include an integrally formed first-stage external fin, a second-stage middle fin, and a third-stage internal fin, and the internal and external fractal fins one and the internal and external fractal fins two face in opposite directions and are staggered in the circumferential direction.

[0004] However, in the circular tube sleeve type heat storage unit in the existing technical solution, the phase change heat storage material (PCM) is placed in the interlayer between the outer tube and the inner tube, and the hot fluid (HTF) passes through the inner side of the inner tube. Since strong convection cannot be formed between the HTF and the PCM, the heat transfer efficiency is low. Even if fins are added to increase the heat transfer area, the heat transfer efficiency is still not ideal. Moreover, when the PCM itself is corrosive, the fins are prone to fouling and corrosion, causing the joint between the fins and the outer wall of the inner tube to break and losing the ability to improve the heat transfer efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a three-arc cross-tank composite graphite phase change heat storage structure for the deficiencies of the existing technology. Through the heat storage unit with a special three-arc structure combined with a specific splicing method, PCM is placed in the heat storage units in multiple regions, and the crescent-shaped gaps formed between adjacent two heat storage units serve as HTF flow channels, with a larger contact area, and turbulence is formed in the flow channels, resulting in higher heat transfer efficiency, more space saving, and the use of a material with a graphite material stacked and coated with a dense coating, enabling the heat storage unit to be applied in harsh environments, including the corrosiveness of PCM, the corrosiveness of HTF, and a higher heat storage temperature range, and solving the technical problems such as unsatisfactory heat transfer efficiency, easy corrosion and fouling, and affecting heat transfer efficiency in the existing technology.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A three-arc cross-type tank composite graphite phase change heat storage structure, comprising: at least two spliced heat storage units, the outer wall surface of the heat storage unit being in a shape formed by a plurality of first arc surfaces and second arc surfaces arranged in a circumferential staggered array, wherein the center of the first arc surface is the center of the tank body and the arc surface bends towards the center of the tank body, and the arc surface of the second arc surface bends away from the center of the tank body; the splicing method of two adjacent heat storage units is that the first arc surface of one heat storage unit is connected to the second arc surface of another heat storage unit with the arc vertex as the intersection point, and a crescent-shaped gap is formed between the two adjacent heat storage units, and this gap serves as the HTF flow channel.

[0007] Preferably, there are three groups of the first arc surfaces and the second arc surfaces respectively, and the circular arc angle of the first arc surface is 60°.

[0008] Preferably, a plurality of the heat storage units are spliced in an annular array manner with one heat storage unit as the center, and each of the first arc surfaces and the second arc surfaces of the heat storage units located in the inner circle is spliced with a heat storage unit.

[0009] The splicing method of a plurality of the heat storage units is: with one heat storage unit as the center, a plurality of heat storage units are spliced around the circumference of this heat storage unit for one circle as the first circle, and then a plurality of heat storage units are spliced around the circumference of the first circle of heat storage units for one circle as the second circle, and so on; among them, there are 6 heat storage units in the first circle, 12 in the second circle, and so on.

[0010] As a preferred embodiment, with one heat storage unit as the center, two circles of heat storage units are spliced in an outer annular array.

[0011] Preferably, adjacent heat storage units are adhesively fixed at the splicing points with graphite glue.

[0012] Preferably, it further includes: an outer shell body, at least two spliced heat storage units are installed in the outer shell body, and a support portion is provided at both ends of the outer shell body in the length direction of the heat storage unit, and the two support portions support and limit the heat storage unit in the length direction; the heat storage units in the outer shell body are arranged in at least one layer in the length direction.

[0013] Preferably, the main body portion of the outer shell body for installing the heat storage unit is in a cylindrical shape and its inner wall is in contact connection with the first arc surface of the heat storage unit.

[0014] Preferably, the heat storage unit includes a tank body and a sealing cover with the same cross-sectional shape and matching for sealed covering.

[0015] Preferably, main ribs and secondary ribs are further arranged inside the tank body. A main rib is connected between each first arc surface and the center of the tank body. A secondary rib is connected between each main rib and the two second arc surfaces on its two sides. The main ribs and secondary ribs divide the tank body into nine areas for placing PCM.

[0016] Preferably, the main rib is connected to the arc midpoint of the first arc surface.

[0017] Preferably, the secondary rib is connected between the midpoint of the main rib and the one-third division point of the second arc surface.

[0018] Preferably, the heat storage unit is made of graphite material and ceramic coatings are coated on its inner and outer surfaces; the sealing cover and the tank body are sealed by coating ceramic coatings.

[0019] Preferably, a stepped sealing structure is adopted between the sealing cover and the tank body.

[0020] Preferably, the height of the tank body is 100 - 500 mm, the wall thickness is 2 - 15 mm, the diameter of the first arc surface is 20 - 200 mm, the circular arc angle of the second arc surface is 50 - 150°, the thickness of the sealing cover is 10 - 50 mm, and the thickness of the ceramic coating is 10 - 100 μm.

[0021] The beneficial effects of the present invention are as follows: (1) Through the special three-arc structure of the heat storage unit combined with the specific splicing method between the heat storage units, in the present invention, the heat storage unit is formed by staggering and arranging a plurality of first arc surfaces and second arc surfaces along the circumference to form a three-arc structure, and PCM is placed therein. The first arc surface and the second arc surface of adjacent heat storage units are spliced with the arc vertex as the intersection point to form a crescent-shaped HTF flow channel, so as to form a way of placing PCM in the tank and flowing HTF in the tank splicing gap. Compared with the traditional circular tube-shell type heat storage unit, this heat exchange structure has a larger contact area, forms a turbulent flow in the flow channel, has a higher heat exchange efficiency, and saves more space; (2) In terms of material selection, the present invention adopts a material of graphite material stacked with a dense coating, so that the heat storage unit can be applied to harsh environments, including the corrosivity of PCM, the corrosivity of HTF, and a higher heat storage temperature range; (3) By arranging main ribs and secondary ribs in the heat storage unit to divide the space inside the tank body into multiple areas, the present invention further improves the heat exchange efficiency by increasing the heat exchange area and adjusting the uniformity of the heat transfer path; (4) In the heat storage structure of the present invention, a crescent-shaped HTF flow channel is formed between adjacent spliced heat storage units, reducing the short-circuit escape phenomenon of HTF, uniformly controlling the flow velocity and flow direction of the HTF fluid, thereby adjusting the flow field of the HTF and increasing the heat transfer area, improving the heat transfer efficiency; avoiding the situation of PCM expanding and overflowing after being heated, and reducing the direct contact between PCM and HTF. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 is Figure 1 the schematic diagram of the structure after removing the outer shell in; Figure 3 It is the front view of the structure of the heat storage unit in the present invention; Figure 4 It is the front view of the splicing structure of the heat storage unit and the outer shell in the present invention; Figure 5 is Figure 1 the front view of; Figure 6 It is the schematic diagram of the structure of the heat storage unit in the present invention; Figure 7 It is the schematic diagram of the structure of the tank body in the present invention; Figure 8 is Figure 7 the front view of; Figure 9 It is the schematic diagram of the structure of the sealing cover in the present invention; Figure 10 It is the temperature field distribution diagram when the conventional circular heat storage unit exchanges heat for 20 min; Figure 11 It is the temperature field distribution diagram when the heat storage unit in the present invention exchanges heat for 20 min (without setting main and secondary ribs); Figure 12 It is the temperature field distribution diagram when the heat storage unit in the present invention exchanges heat for 19 min (without setting main and secondary ribs); Figure 13 It is the temperature field distribution diagram when the heat storage unit in the present invention exchanges heat for 19 min (with main ribs set); Figure 14 It is the temperature field distribution diagram when the heat storage unit in the present invention exchanges heat for 15 min (with main and secondary ribs set); Figure 15 It is the temperature field distribution diagram when the conventional circular heat storage unit exchanges heat for 19 min (with main and secondary ribs set). Detailed Embodiment

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0025] Embodiment 1 As Figures 2 - 4 shown, a three-arc cross-tank composite graphite phase change heat storage structure includes: at least two mutually spliced heat storage units I. The outer wall surface of the heat storage unit I is in a shape formed by a plurality of first arc surfaces 11 and second arc surfaces 12 arranged in a circumferential staggered array. Among them, the center of the first arc surface 11 is the center of the tank body 1 and the arc surface bends towards the center of the tank body 1, and the arc surface of the second arc surface 12 bends 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 another heat storage unit I with the arc vertex as the intersection point, and a crescent-shaped gap is formed between the two adjacent heat storage units I. This gap serves as the HTF flow channel 5.

[0026] In this embodiment, through the special three-arc structure of the heat storage unit I combined with a specific splicing method between the heat storage units I, a way is formed in which the PCM is placed in the heat storage unit I and the HTF flows in the splicing gap between the heat storage units I. Compared with the traditional circular tube-sheet heat storage unit, this heat exchange structure has a larger contact area and forms a turbulent flow in the flow channel. Specifically, by reducing the gap between each heat exchange unit, the flow velocity is increased. The crescent-shaped HTF flow channel 5 has relative irregularity in cross-section. When the fluid passes through, due to the flow velocity and cross-section irregularity, a turbulent flow state is formed. While increasing the flow resistance, the heat exchange efficiency is increased, and the space is more saved.

[0027] Preferably, adjacent heat storage units I are adhesively fixed at the splicing points with graphite glue.

[0028] When assembling the heat storage structure of this embodiment, the heat storage units I are placed vertically for assembly, and the crescent-shaped HTF flow channel 5 is positioned with a plug gauge. After brushing with graphite glue for adhesive fixation, the plug gauge is then withdrawn.

[0029] Preferably, as Figures 1 - 2 shown, it further includes: an outer shell II, at least two mutually spliced heat storage units I are installed in the outer shell II, and a support portion 6 is provided at both ends of the outer shell II in the length direction of the heat storage unit I. The two support portions 6 perform support and limit on the heat storage unit I in the length direction.

[0030] Preferably, the heat storage units I in the outer shell II are arranged in at least one layer along the length direction.

[0031] As a preferred implementation manner, in this embodiment, as Figure 2 shown, three layers of the heat storage unit I are provided in the outer shell II.

[0032] Embodiment Two In this embodiment, the same or corresponding components as those in the above embodiment are denoted by the corresponding reference numerals in the above embodiment. For the sake of simplicity, only the differences from the above embodiment will be described below. The differences between this embodiment and the above embodiment are as follows: Preferably, as Figure 3 shown, three groups are provided on each of the first arc surface 11 and the second arc surface 12, and the circular arc angle of the first arc surface 11 is 60°.

[0033] As a supplementary explanation, the outer wall surface shape of the heat storage unit I is the cross-sectional shape obtained after the second arc surface 12 and the circular base are cross-cut by three equal arcs. The remaining arc after the circular base is cut is the first arc surface 11.

[0034] When at least two of the heat storage units I are spliced, as Figure 4As shown, the orientations of all the heat storage units I are the same. The same orientation means that, for example, Figure 3 as shown, all the heat storage units are arranged with one of the first arc surfaces 11 facing directly upward.

[0035] Embodiment III For the same or corresponding components in this embodiment and the above embodiments, the corresponding reference numerals in the above embodiments are used. For the sake of simplicity, only the differences from the above embodiments will be described below. The differences between this embodiment and the above embodiments are as follows: Preferably, for example, Figure 4 as shown, several of the heat storage units I are spliced in an annular array centered on one heat storage unit I, and one heat storage unit I is spliced to each of the first arc surfaces 11 and the second arc surfaces 12 of the heat storage units I located in the inner circle.

[0036] As a supplementary explanation, the splicing method of several of the heat storage units I is as follows: Centered on one heat storage unit I, several heat storage units I are spliced around the circumferential direction of this heat storage unit I as the first circle, and then several heat storage units I are spliced around the circumferential direction of the first circle of heat storage units I as the second circle, and so on; among them, there are 6 heat storage units I in the first circle, 12 in the second circle, and so on.

[0037] As a preferred implementation manner, in the heat storage structure of this embodiment, two circles of heat storage units I are spliced in an outer annular array centered on one heat storage unit I.

[0038] Preferably, matching the heat storage units I spliced in the annular array, the main body part of the outer housing II for installing the heat storage units I is provided in a cylindrical shape and its inner wall is in contact connection with the first arc surface 11 of the heat storage units I.

[0039] Embodiment IV For the same or corresponding components in this embodiment and the above embodiments, the corresponding reference numerals in the above embodiments are used. For the sake of simplicity, only the differences from the above embodiments will be described below. The differences between this embodiment and the above embodiments are as follows: Preferably, for example, 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 sealed closure.

[0040] Preferably, for example, Figures 7 - 8 as shown, main ribs 3 and secondary ribs 4 are further provided in the tank body 1. One of the main ribs 3 is connected between each of the first arc surfaces 11 and the center of the tank body 1. One of the secondary ribs 4 is connected between each of the main ribs 3 and the two second arc surfaces 12 on its two sides. The main ribs 3 and the secondary ribs 4 divide the tank body 1 into nine regions for placing PCM.

[0041] In this embodiment, by arranging main ribs 3 and secondary ribs 4 in the heat storage unit I, the space inside the tank body 1 is divided into multiple regions, and further, the heat exchange efficiency is improved by increasing the heat exchange area and adjusting the uniformity of the heat transfer path.

[0042] Specifically, the phase change heat storage material has a low thermal conductivity, while the heat storage unit I, as a modified graphite material, has a relatively high thermal conductivity. By arranging the main and secondary ribs, the heat on the outer surface of the heat storage unit I can be quickly transferred to the center of the phase change heat storage material along the paths of the main and secondary ribs, rather than relying entirely on the heat transfer of the phase change heat storage material itself to the center. The main and secondary ribs are equivalent to increasing the heat exchange area between the heat storage unit I and the phase change heat storage material.

[0043] Preferably, the main rib 3 is connected to the arc midpoint of the first arc surface 11.

[0044] Preferably, the secondary rib 4 is connected and arranged between the midpoint of the main rib 3 and the one-third division point of the second arc surface 12.

[0045] Preferably, a stepped sealing structure is adopted between the sealing cover 2 and the tank body 1.

[0046] As Figure 9 As shown, in this embodiment, as a preferred implementation manner, the bottom surface of the sealing cover 2 has a convex platform 21, the outer diameter of the convex platform 21 is slightly adapted to the inner diameter of the tank body 1, and a groove adapted to the shape and size of the convex platform 21 is arranged in a matching manner inside the tank body 1. Thus, when the sealing cover 2 is covered on the tank body 1, the convex platform 21 extends into the tank body 1 and cooperates with the groove, so as to achieve stepped multi-stage sealing between the two.

[0047] 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.

[0048] Embodiment Five For the same or corresponding components in this embodiment and the above embodiments, the corresponding reference numerals in the above embodiments are adopted. For the sake of simplicity, only the differences from the above embodiments are described below. The differences between this embodiment and the above embodiments are as follows: Preferably, the heat storage unit I is made of graphite material and ceramic coatings are coated on its inner and outer surfaces.

[0049] Preferably, the sealing cover 2 and the tank body 1 are sealed by coating ceramic coatings.

[0050] Preferably, the thickness of the ceramic coating is 10 - 100 μm.

[0051] It should be noted that the coating process is to spray the well-proportioned ceramic coating and then sinter it. At the sealed part of the sealing cover 2 and the tank body 1, during the sintering process, the coating will evaporate and then adhere to the surface of the heat storage unit body, connecting with the upper and lower parts to form a dense ceramic coating. It can be understood that the ceramic coating at the gap will connect with the ceramic coatings of the sealing cover 2 and the tank body 1 to form the same dense ceramic coating, wrapping the gap inside, thereby achieving sealing.

[0052] As a preferred embodiment, the ceramic coating specifically adopts a silicon carbide coating.

[0053] In terms of material selection in this embodiment, a material with a graphite material overlaid with a dense coating is used, enabling the heat storage unit I to be applied in harsh environments, including the corrosiveness of PCM, the corrosiveness of HTF, and a higher heat storage temperature range, being high-temperature resistant, corrosion resistant, and impermeable, with a temperature application range of -100~1500°C.

[0054] In the triple-arc cross-tank composite graphite phase change heat storage structure of the present invention, a crescent-shaped HTF flow channel is formed between adjacent spliced heat storage units, reducing the short-circuit escape phenomenon of HTF, uniformly controlling the flow rate and flow direction of the HTF fluid, thereby adjusting the flow field of HTF and increasing the heat transfer area, improving the heat transfer efficiency; avoiding the situation of PCM expanding and overflowing after being heated, and reducing the direct contact between PCM and HTF.

[0055] As a supplementary explanation, compared with the gap formed by four circular heat storage units tangent to each other, the crescent-shaped HTF flow channel 5 in the present invention is more narrow and long and has a smaller area. The narrow and long shape makes the effective specific heat transfer area of HTF contacting the heat storage unit I larger, and the smaller area reduces the proportion of HTF escaping without heat transfer; the situation of PCM expanding and overflowing and contacting HTF is avoided by the form of covering and sealing the heat storage unit I.

[0056] As Figure 10 shown, for the regularly circularly arranged heat storage units, the unit calculation model is as follows. The four regions at the four corners of the externally tangent square are the HTF flow regions. When supplied with a 550K HTF heat source for 20 minutes, it can be seen that most of the central region is still around 400K. And as Figure 11 shown, for the triple-arc heat storage units in this embodiment, through the shape characteristics and layout characteristics, six crescent-shaped HTF flow regions can be formed. Under the same 550K heat source supply, at 20 minutes, it has already reached isothermal with HTF. It can be seen that this triple-arc shape has a significant effect on improving the heat transfer efficiency; as Figure 12As 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, 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, Figure 14 As shown, it only takes 15 minutes to achieve a PCM temperature of 550K inside the entire thermal storage unit. It can be seen that adding 3 main ribs and 4 secondary ribs can further greatly improve the heat exchange efficiency (increase by 25%). However, this form of adding primary ribs 3 and secondary ribs 4 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 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 rapid heat transfer guide. Compared with the circular section, the guiding effect of the primary and secondary ribs of the three-arc type 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, 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.

[0057] 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 protection scope 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) connected to each other, wherein the outer wall surface of the heat storage unit (I) is in a shape formed by a plurality of first curved surfaces (11) and second curved surfaces (12) arranged in an array staggered along a circumference, wherein the center of the first curved surface (11) is the center of the tank body (1) and the curved surface is bent toward the center of the tank body (1), and the curved surface of the second curved surface (12) is bent 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 is characterized in that: The first arc surface (11) and the second arc surface (12) are each provided in three groups, 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 joint points 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), at least two mutually spliced ​​heat storage units (I) are installed in the outer shell (II), 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; 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) used to mount the heat storage unit (I) is arranged in a cylindrical shape, and its inner wall is in contact with the first curved 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 curved surfaces (11) and the center of the tank body (1); a secondary rib (4) is connected between each of the main ribs (3) and two of the second curved surfaces (12) on both sides thereof; each of the main ribs (3) and the secondary ribs (4) divides 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 curved surface (11) is 20-200 mm, the arc angle of the second curved 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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