Modular phase change molten salt heat storage device and method
By using a modular design and a multi-stage heat transfer structure, the phase change molten salt thermal energy storage device resolves the contradiction between high-temperature molten salt corrosion and enhanced heat transfer, achieving efficient and flexible thermal energy storage and release, and improving the reliability and safety of the system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN THERMAL POWER RES INST CO LTD
- Filing Date
- 2026-03-02
- Publication Date
- 2026-05-29
AI Technical Summary
In existing molten salt thermal storage technologies, the contradiction between high-temperature molten salt corrosion, heat transfer enhancement, and structural reliability is difficult to resolve. In particular, in the high-temperature zone, halogen salts are highly corrosive to metallic materials, heat transfer enhancement materials are prone to corrosion and failure in molten salt, and the connection interface is prone to cracking and leakage.
The phase change molten salt thermal energy storage device adopts a modular design. Through modular stacking of thermal energy storage units, flexible heat-conducting layers and multi-stage heat transfer body structure, combined with electric heating and external heat exchange fluid, it achieves temperature-corrosivity graded matching, enhances internal heat transfer and prevents structural cracking.
It achieves efficient and flexible thermal energy storage and release, reduces leakage risk, improves system reliability and maintainability, adapts to different engineering needs, and enhances heat transfer efficiency and safety.
Smart Images
Figure CN122107841A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of molten salt thermal energy storage technology, specifically to a modular phase change molten salt thermal energy storage device and method. Background Technology
[0002] As the global energy structure accelerates its transition to renewable energy, thermal storage technology, especially phase change thermal storage, has become crucial due to its high energy density and wide operating temperature range. Molten salt phase change thermal storage is considered one of the most promising technological pathways, but its transition from laboratory to large-scale engineering applications faces a series of intertwined and complex core challenges.
[0003] The primary challenge lies in the inherent contradictions within the material system. The operating temperature of molten salt is directly related to its corrosiveness: nitrates in the low-to-medium temperature range pose a long-term corrosion risk to metal containers; while in the high-temperature range above 550°C, chlorides and other halides are required to achieve high energy levels, which are highly corrosive to most metals, leading to exorbitant costs for corrosion-resistant special alloys. Simultaneously, the inherent low thermal conductivity of phase change materials necessitates the introduction of high thermal conductivity strengthening materials, but these materials are prone to corrosion failure in molten salt. This highlights the conflict between enhanced heat transfer and structural reliability. Metal fins or ribs incorporated to enhance heat transfer become vulnerable to corrosion and thermomechanical fatigue at their interface with the container body under harsh conditions of high temperature, strong corrosion, and periodic phase change volume variations. Traditional rigid connection structures struggle to accommodate differences in thermal expansion coefficients between different materials, and repeated thermal cycling can easily lead to cracking, leakage, and other failures. Summary of the Invention
[0004] The purpose of this invention is to provide a modular phase change molten salt thermal storage device and method to overcome and effectively solve the contradiction between high-temperature molten salt corrosion, heat transfer enhancement and structural reliability.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a modular phase change molten salt thermal storage device, comprising: A thermal storage unit module is composed of at least one thermal storage unit stacked vertically. The thermal storage unit includes a molten salt box, which is used to encapsulate phase change molten salt; The first heat transfer element is disposed inside the molten salt box and immersed in the phase change molten salt to enhance heat transfer inside the molten salt box; The second heat transfer element is in thermal contact with the outer wall of the molten salt box and is used for heat exchange with the external heat exchange fluid. A heating element, thermally connected to the molten salt box, is used to provide heat to the molten salt box; A collection pipeline for allowing the heat exchange fluid to flow through the second heat transfer body in at least one heat storage unit; A support structure for supporting the at least one thermal storage unit and the collecting pipeline.
[0006] Furthermore, the phase change molten salt occupies 80% to 90% of the internal volume of the molten salt box; the first heat transfer body is an enhanced heat transfer structure, and the second heat transfer body includes a heat exchange tube shell and a heat exchange tube. The heat exchange tube shell has a hole, and the heat exchange tube passes through the hole in the heat exchange tube shell. The heat exchange tube shell is in thermal contact with the side wall of the molten salt box.
[0007] Furthermore, the heating assembly includes a molten salt box support base, in which an electric heating tube is embedded; the molten salt box support base is fixedly connected to the bottom of the molten salt box, and the top of the molten salt box support base is provided with a groove for accommodating the electric heating tube.
[0008] Furthermore, a flexible thermally conductive material is filled between the heat exchange tube shell and the side wall of the molten salt box, and highly thermally conductive particles are filled in the gap between the heat exchange tube and the heat exchange tube shell.
[0009] Furthermore, the first heat transfer element is one or more combinations of fins, ribs, needle arrays, or foam metal structures.
[0010] Furthermore, the flexible thermally conductive material is thermally conductive silicone grease, thermally conductive phase change material, flexible graphite pad, or metal fiber felt; the high thermal conductivity particles are one or more of aluminum nitride, boron nitride, beryllium oxide, or high thermal conductivity metal particles, and the particle size of the high thermal conductivity particles is 0.5 mm to 5 mm.
[0011] Furthermore, the inner wall of the groove of the molten salt box support and the outer wall of the electric heating tube are filled with an insulating, highly thermally conductive material.
[0012] Furthermore, the collecting pipeline includes an upper collecting pipe and a lower collecting pipe, the upper collecting pipe being connected to the upper ends of the plurality of heat exchange tubes, and the lower collecting pipe being connected to the lower ends of the plurality of heat exchange tubes.
[0013] Furthermore, the upper manifold and / or the lower manifold are provided with expansion joints.
[0014] Secondly, the present invention also provides an operation method for a modular phase change molten salt thermal storage device, applied to the aforementioned modular phase change molten salt thermal storage device, the method comprising: The heating element is activated, allowing heat to be transferred to the molten salt box through a thermally conductive connection, thereby heating the phase change molten salt encapsulated in the molten salt box. The phase change molten salt absorbs heat, undergoes a phase change, and stores thermal energy. The heat exchange fluid flows into the collecting pipe and passes through the second heat transfer body in the at least one heat storage unit; the heat exchange fluid exchanges heat with the molten salt box through the second heat transfer body, absorbing the heat stored in the phase change molten salt; the heated heat exchange fluid flows out of the collecting pipe for use.
[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a modular phase change molten salt thermal storage device. The modular design of the thermal storage units allows for the selection of the most suitable phase change molten salt material according to different temperature zones. By stacking thermal storage units with different material systems vertically, temperature-corrosion grading matching of the entire thermal storage device is achieved, avoiding extreme requirements on a single material system. The modular and independent molten salt box design confines the volume change and thermal stress of each thermal storage unit within a single box during thermal cycling, reducing the cascading impact on the overall structure. This invention also innovatively incorporates an internal first heat transfer body and an external second heat transfer body. The first heat transfer body directly enhances heat transfer within the phase change material, effectively overcoming the bottleneck of low thermal conductivity of the phase change material. The second heat transfer body is responsible for efficient heat exchange with the external fluid, achieving rapid response of storage / release power.
[0016] Specifically, this invention incorporates a flexible thermally conductive layer between the molten salt box and the heat exchange shell, and fills the gaps between the heat exchange tubes with thermally conductive particles that are allowed to shift, forming a multi-level flexible thermally conductive interface. This effectively absorbs stress generated by thermal expansion differences, preventing structural cracking. The modular unit design allows for adjustment of the heat storage capacity by increasing or decreasing the number of molten salt boxes stacked, and power adjustment by changing the heat exchange surface. This decoupling of "power" and "capacity" enables the device to flexibly adapt to engineering needs of different scales, improving reliability and maintainability.
[0017] Specifically, this invention compactly integrates three major functions: electric heating, phase change heat storage, and fluid heat exchange. The unique bottom grooved design enables efficient coupling between the electric heating element and molten salt, resulting in rapid heat storage. The side interface allows for efficient coupling with an external heat exchanger, ensuring independent and stable heat release channels. This design reduces complex external piping, improves system compactness and volumetric energy density, lowers leakage risk, and achieves faster thermal response, providing support for safe and efficient system operation and flexible participation in grid regulation. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the modular phase change molten salt thermal storage device in an embodiment of the present invention.
[0019] Figure 2 This is a cross-sectional schematic diagram of the modular phase change molten salt thermal storage device in an embodiment of the present invention.
[0020] Figure 3This is a front view schematic diagram of the modular phase change molten salt thermal storage device in an embodiment of the present invention.
[0021] In the diagram, 1 is the heat exchange tube; 2 is the molten salt box; 3 is the electric heating tube; 4 is the molten salt box support; 5 is the heat exchange tube shell; 6 is the flexible thermal conductive material; 7 is the enhanced heat transfer structure; 8 is the upper manifold; and 9 is the lower manifold. Detailed Implementation
[0022] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.
[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.
[0025] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0026] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0027] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.
[0028] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.
[0029] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.
[0030] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.
[0031] See Figures 1 to 3 This invention provides a modular phase change molten salt thermal storage device, comprising: A thermal storage unit module is composed of at least one thermal storage unit stacked vertically. The thermal storage unit includes a molten salt box 2, which is used to encapsulate phase change molten salt; The first heat transfer element is disposed inside the molten salt box 2 and immersed in the phase change molten salt to enhance the heat transfer inside the molten salt box 2; The second heat transfer element is in thermal contact with the outer wall of the molten salt box 2 and is used for heat exchange with the external heat exchange fluid. The heating element is thermally connected to the molten salt box 2 and is used to provide heat to the molten salt box 2; A manifold for allowing heat exchange fluid to flow through a second heat transfer medium in at least one heat storage unit; Support structure for supporting at least one thermal storage unit and collection piping.
[0032] The heat generated when the heating element is activated is directly transferred to the wall of the molten salt box 2 through a thermally conductive connection established with it. The heat is then introduced into the encapsulated phase-change molten salt inside the box 2. After absorbing heat, the phase-change molten salt inside the box 2 heats up. When its temperature reaches the phase change point, a phase change process occurs from solid to liquid. This process absorbs and stores a large amount of latent heat of phase change, achieving high-energy-density thermal energy storage. Simultaneously, the first heat transfer element, located inside the molten salt box 2 and immersed in the phase-change molten salt, plays a crucial role in enhancing internal heat transfer. The first heat transfer element increases the effective heat transfer area inside the molten salt box 2 and, through its high thermal conductivity, accelerates the diffusion and homogenization of heat from the wall of the box 2 towards the internal molten salt, especially towards the central region of the box 2. This effectively overcomes the low thermal conductivity of the phase-change molten salt itself, significantly shortens the overall melting and storage time of the heat storage unit, and improves the heat storage power and uniformity.
[0033] When the external system requires heat energy, the low-temperature heat exchange fluid flows into the manifold under power. The manifold distributes the heat exchange fluid and guides it through the second heat transfer body of at least one heat storage unit in the heat storage unit module. The second heat transfer body maintains thermally conductive contact with the outer wall of the molten salt box 2, forming a key channel for heat transfer from the inside of the molten salt box 2 to the external heat exchange fluid. The heat stored in the phase change molten salt is conducted to the second heat transfer body through the wall of the molten salt box 2. When the low-temperature heat exchange fluid flows through the second heat transfer body, it undergoes forced convection heat transfer with the surface of the second heat transfer body, absorbing heat and increasing its temperature. The heated heat exchange fluid flows out of the second heat transfer body, is collected through the manifold, and then output to supply downstream heat-using equipment or systems. In this process, the first heat transfer body also plays a role, enhancing the transfer of heat from the inside of the molten salt to the wall of the molten salt box 2 during solidification, ensuring the rapid and efficient heat release process.
[0034] In this embodiment, the device achieves system scalability through modular stacking; the cooperation between the heating element and the first heat transfer body enables efficient and uniform heating and heat storage of the phase change molten salt; and the cooperation between the second heat transfer body and the collecting pipeline enables on-demand, controllable, and efficient release of stored thermal energy. The molten salt box 2, as the encapsulation core, ensures the working environment and safety of the phase change material.
[0035] In a more specific embodiment of the present invention, the filling volume of the phase change molten salt occupies 80% to 90% of the internal volume of the molten salt box 2. Necessary expansion space is reserved during the phase change melting process of the molten salt. This expansion space serves as a gas-phase buffer chamber to accommodate the volume increase of the molten salt as it changes from a solid to a liquid state, preventing a sharp increase in pressure within the molten salt box due to overfilling. Specifically, when the phase change temperature of the phase change molten salt is below or equal to 350°C, the phase change molten salt is a nitrate mixture, which is a eutectic or near-eutectic salt of sodium nitrate and potassium nitrate. The molten salt box 2 is made of corrosion-resistant stainless steel. The enhanced heat transfer structure 7 is a composite structure of corrosion-resistant stainless steel coated with a high thermal conductivity core material, which is copper, aluminum, or graphite. When the phase change temperature of the molten salt is higher than or equal to 550℃, the molten salt is a mixture of halide salts. The molten salt box 2 is made of integral ceramic, metal surface enamel, or high-nickel-based corrosion-resistant alloy. The heat transfer strengthening structure 7 is made of isostatic graphite, sintered silicon carbide, or high thermal conductivity graphite with an anti-oxidation surface treatment. The halide salt mixture is a eutectic or near-eutectic mixture formed by two or more of sodium chloride, potassium chloride, and magnesium chloride. This invention uses differentiated material matching to address the corrosion characteristics of molten salts in different temperature zones. For low-temperature nitrate environments, composite fins with a "stainless steel-clad copper core" are used, combining high thermal conductivity and corrosion resistance. For high-temperature halide salt environments, isostatic graphite or special ceramics and other corrosion-resistant, high thermal conductivity materials are selected, providing a feasible solution for extreme operating conditions. This temperature-zone material selection strategy fundamentally overcomes the bottleneck of insufficient performance of traditional single materials, significantly improving heat transfer efficiency while ensuring long-term operational reliability.
[0036] The first heat transfer element is the enhanced heat transfer structure 7, and the second heat transfer element includes a heat exchange tube shell 5 and a heat exchange tube 1. The heat exchange tube shell 5 has holes, and the heat exchange tube 1 passes through these holes. The heat exchange tube shell 5 is in thermally conductive contact with the side wall of the molten salt box 2. During heat storage, heat is rapidly conducted from the wall of the molten salt box 2 to the enhanced heat transfer structure 7, and then efficiently transferred to the surrounding solid or liquid molten salt through its extended surface. During heat release, the process is reversed; heat rapidly accumulates from the molten salt to the wall of the molten salt box 2 through the enhanced heat transfer structure 7. In this embodiment, the effective heat transfer area on the molten salt side is significantly increased. The enhanced heat transfer structure 7 acts like an internal heat pipe network, accelerating the longitudinal and lateral diffusion of heat within the molten salt box 2, reducing the internal temperature gradient, preventing localized overheating or solidification, and improving material utilization and cycle life.
[0037] In a more specific embodiment of the present invention, the first heat transfer element is one or more combinations of fins, ribs, needle arrays, or foam metal structures.
[0038] In a more specific embodiment of the present invention, the heating assembly includes a molten salt box support 4, with an electric heating tube 3 embedded inside the molten salt box support 4. The molten salt box support 4 is fixedly connected to the bottom of the molten salt box 2, and the top of the molten salt box support 4 has a groove for accommodating the electric heating tube 3. An insulating, highly thermally conductive material is filled between the inner wall of the groove of the molten salt box support 4 and the outer wall of the electric heating tube 3. The heat generated by the electric heating tube 3 is first transferred to the groove wall in close contact with it, and then rapidly diffused through the high thermal conductivity metal substrate of the molten salt box support 4. This "surface heating" mode avoids localized high-temperature hotspots, ensuring uniform heating of the bottom of the molten salt box 2, which is beneficial for the synchronous melting of the internal phase-change molten salt and reduces thermal stress.
[0039] The flexible thermally conductive material 6 is thermally conductive silicone grease, thermally conductive phase change material, flexible graphite pad, or metal fiber felt; the high thermal conductivity particles are one or more of aluminum nitride, boron nitride, beryllium oxide, or high thermal conductivity metal particles, and the particle size of the high thermal conductivity particles is 0.5 mm to 5 mm.
[0040] In a more specific embodiment of the present invention, the manifold includes an upper manifold 8 and a lower manifold 9. The upper manifold 8 is connected to the upper ends of multiple heat exchange tubes 1, and the lower manifold 9 is connected to the lower ends of multiple heat exchange tubes 1. Typically, the low-temperature heat exchange fluid enters from the lower manifold 9. The lower manifold 9 acts as a pressure-equalizing distribution chamber, uniformly distributing the incoming fluid to the lower inlet of each heat exchange tube 1 connected to it. Subsequently, the fluid flows upward through dozens or even hundreds of parallel heat exchange tubes 1, exchanging heat with the heat storage unit through the tube wall and absorbing heat to increase its temperature. All the heated fluid flows out from the upper outlet of each heat exchange tube 1 and converges into the upper manifold 8. The upper manifold 8 mixes and merges the hot fluid from all parallel channels into a single flow, which is then transported to an external heating system. This flow pattern is advantageous for utilizing the natural upward trend of the hot fluid, reducing flow resistance, and facilitating the discharge of any gases that may accumulate in the system.
[0041] In a more specific embodiment provided by the present invention, an expansion joint is provided on the upper manifold 8 and / or the lower manifold 9.
[0042] This invention also provides an operation method for a modular phase change molten salt thermal storage device, applicable to the modular phase change molten salt thermal storage device, the method comprising: Thermal storage process: The heating element is activated, and heat is transferred to the molten salt box 2 through the thermal connection to heat the phase change molten salt encapsulated in the molten salt box 2. The phase change molten salt absorbs heat, undergoes phase change, and stores thermal energy. Heat release process: The heat exchange fluid flows into the collection pipe and passes through the second heat transfer body in at least one heat storage unit; the heat exchange fluid exchanges heat with the molten salt box 2 through the second heat transfer body and absorbs the heat stored in the phase change molten salt; the heated heat exchange fluid flows out of the collection pipe for use.
[0043] In this embodiment, the heat storage process specifically includes: activating the electric heating tube 3 embedded in the molten salt box support 4, and transferring heat sequentially through the molten salt box support 4 and the bottom of the molten salt box 2 to the phase change molten salt. The first heat transfer body, which is set inside the molten salt box 2 and immersed in the phase change molten salt, enhances the heat transfer process inside the molten salt box 2, so that the heat is evenly distributed.
[0044] In this embodiment, the heat release process specifically includes: allowing the heat exchange fluid to flow sequentially through the lower collecting pipe 9, multiple heat exchange tubes 1 inserted in the heat exchange tube shell 5, and the upper collecting pipe 8; the heat exchange tube shell 5 is in thermal contact with the side wall of the molten salt box 2; heat is transferred to the heat exchange fluid in the heat exchange tube 1 through the side wall of the molten salt box 2 and the heat exchange tube shell 5; the high thermal conductivity particles filled in the gap between the heat exchange tube 1 and the heat exchange tube shell 5; and the flexible thermally conductive material 6 filled between the heat exchange tube shell 5 and the side wall of the molten salt box 2, together enhancing external heat exchange.
[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.
Claims
1. A modular phase change molten salt thermal storage device, characterized in that, include: A thermal storage unit module is composed of at least one thermal storage unit stacked vertically. The thermal storage unit includes a molten salt box (2) for encapsulating phase change molten salt; The first heat transfer body is disposed in the molten salt box (2) and immersed in the phase change molten salt to enhance the heat transfer inside the molten salt box (2); The second heat transfer body is in thermal contact with the outer wall of the molten salt box (2) and is used to exchange heat with the external heat exchange fluid. A heating element is thermally connected to the molten salt box (2) to provide heat to the molten salt box (2); A collection pipeline for allowing the heat exchange fluid to flow through the second heat transfer body in at least one heat storage unit; A support structure for supporting the at least one thermal storage unit and the collecting pipeline.
2. The modular phase change molten salt thermal storage device according to claim 1, characterized in that, The phase change molten salt filling volume accounts for 80% to 90% of the internal volume of the molten salt box (2); the first heat transfer body is an enhanced heat transfer structure (7); the second heat transfer body includes a heat exchange tube shell (5) and a heat exchange tube (1); the heat exchange tube shell (5) has a hole; the heat exchange tube (1) passes through the hole in the heat exchange tube shell (5); the heat exchange tube shell (5) is in thermal contact with the side wall of the molten salt box (2).
3. The modular phase change molten salt thermal storage device according to claim 2, characterized in that, The heating assembly includes a molten salt box support base (4), in which an electric heating tube (3) is embedded; the molten salt box support base (4) is fixedly connected to the bottom of the molten salt box (2), and the top of the molten salt box support base (4) is provided with a groove for accommodating the electric heating tube (3).
4. A modular phase change molten salt thermal storage device according to claim 2, characterized in that, The heat exchange tube shell (5) and the side wall of the molten salt box (2) are filled with flexible thermally conductive material (6), and the gap between the heat exchange tube (1) and the heat exchange tube shell (5) is filled with highly thermally conductive particles.
5. A modular phase change molten salt thermal storage device according to claim 2, characterized in that, The first heat transfer element is one or more combinations of fins, ribs, needle arrays, or foam metal structures.
6. A modular phase change molten salt thermal storage device according to claim 4, characterized in that, The flexible thermally conductive material (6) is thermally conductive silicone grease, thermally conductive phase change material, flexible graphite pad or metal fiber felt; the high thermal conductivity particles are one or more of aluminum nitride, boron nitride, beryllium oxide or high thermal conductivity metal particles, and the particle size of the high thermal conductivity particles is 0.5 mm to 5 mm.
7. A modular phase change molten salt thermal storage device according to claim 2, characterized in that, The groove inner wall of the molten salt box support (4) and the outer wall of the electric heating tube (3) are filled with an insulating high thermal conductivity material.
8. A modular phase change molten salt thermal storage device according to claim 2, characterized in that, The collection pipeline includes an upper collection pipe (8) and a lower collection pipe (9). The upper collection pipe (8) is connected to the upper end of a plurality of heat exchange tubes (1), and the lower collection pipe (9) is connected to the lower end of a plurality of heat exchange tubes (1).
9. A modular phase change molten salt thermal storage device according to claim 8, characterized in that, Expansion joints are provided on the upper manifold (8) and / or the lower manifold (9).
10. An operation method for a modular phase change molten salt thermal storage device, characterized in that, The method, applied to the modular phase change molten salt thermal storage device according to any one of claims 1 to 9, comprises: The heating element is activated so that heat is transferred to the molten salt box (2) through the thermal connection to heat the phase change molten salt encapsulated in the molten salt box (2). The phase change molten salt absorbs heat, undergoes a phase change, and stores thermal energy. The heat exchange fluid flows into the collection pipe and passes through the second heat transfer body in the at least one heat storage unit; the heat exchange fluid exchanges heat with the molten salt box (2) through the second heat transfer body and absorbs the heat stored in the phase change molten salt; the heated heat exchange fluid flows out of the collection pipe for use.