Efficient phase change heat storage device based on inner pipe compound motion and control method of efficient phase change heat storage device

Abstract

The invention relates to the technical field of phase change heat storage, and provides an efficient phase change heat storage device based on inner pipe compound motion and a control method thereof.The efficient phase change heat storage device comprises an outer pipe, an inner pipe arranged in the outer pipe, an inner pipe translation mechanism and an inner pipe rotating mechanism which are arranged at the end of the inner pipe, and a phase change material filled between the inner pipe and the outer pipe; two rectangular fins are symmetrically arranged on the outer side of the inner pipe; the inner pipe translation mechanism is used for performing composite motion with the inner pipe rotating mechanism in the early stage of the heat storage process, driving the inner pipe to approach the bottom of the outer pipe in the later stage of the heat storage process, and driving the inner pipe to approach the top of the outer pipe in the heat release process; and the inner pipe rotating mechanism is used for performing composite motion with the inner pipe translation mechanism in the early stage of the heat storage process and driving the inner pipe to rotate to the position where the rectangular fins are kept in up-and-down arrangement in the later stage of the heat storage process and the heat release process. On the basis of achieving the maximum enhancement degree of the heat storage / release rate, the energy consumption caused by movement of the inner pipe is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change heat storage, and in particular to a high-efficiency phase change heat storage device based on the composite motion of an inner tube and a control method thereof. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] Phase change heat storage technology can utilize phase change materials to effectively realize heat recovery and utilization. At present, the main technical bottleneck of phase change heat storage technology is the poor thermal conductivity of phase change materials, which leads to long heat storage / release time and low heat storage / release efficiency of phase change heat storage devices, resulting in the inability to meet the use requirements of heat recovery application scenarios.

[0004] Passive enhancement methods for phase-change thermal storage technology primarily include adding fins, nanoparticles, and changing the shape of the inner and outer tubes. While this approach requires no additional energy, the addition of fins and nanoparticles reduces the mass of the phase-change material within the thermal storage device, impacting its performance. Furthermore, this enhancement method has a certain enhancement limit and cannot achieve higher thermal storage and release performance.

[0005] The active enhancement methods of phase change heat storage technology mainly include inner / outer tube rotation, inner tube translation, and external electric or magnetic fields. The effect of active enhancement is better than that of passive enhancement, and it can break through the enhancement limit of the original passive enhancement method to achieve better heat storage / release performance. However, this enhancement method requires the consumption of external energy. If you want to further improve the enhancement effect, the external energy consumption will be further increased. At the same time, additional mechanical components need to be arranged, and the complexity of the system is further increased. In addition, this enhancement method also has a certain enhancement limit and cannot achieve higher heat storage / release performance. Summary of the Invention

[0006] In order to address the shortcomings of the existing technology, the present invention provides a high-efficiency phase change heat storage device based on the composite movement of the inner tube and a control method thereof. Based on the passive reinforcement method of adding fins, an active reinforcement method of the inner tube movement is applied. Through different inner tube movement strategies, the maximum degree of reinforcement of the storage / release rate can be achieved, while reducing the energy consumption caused by the movement of the inner tube and improving the economy.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: A first aspect of the present invention provides a high-efficiency phase-change heat storage device based on the composite motion of an inner tube.

[0008] A high-efficiency phase-change heat storage device based on the composite motion of an inner tube comprises an outer tube, an inner tube disposed within the outer tube, an inner tube translation mechanism and an inner tube rotation mechanism disposed at the ends of the inner tube, and a phase-change material filled between the inner tube and the outer tube. Two rectangular fins are symmetrically disposed on the outer side of the inner tube. The inner tube translation mechanism is used to perform a composite motion with the inner tube rotation mechanism in the early stage of the heat storage process, drive the inner tube closer to the bottom of the outer tube in the late stage of the heat storage process, and drive the inner tube closer to the top of the outer tube in the heat release process; The inner tube rotation mechanism is used to perform a composite motion with the inner tube translation mechanism in the early stage of the heat storage process, drive the inner tube to rotate to a position where the rectangular fins are kept arranged up and down in the late stage of the heat storage process, and drive the inner tube to rotate to a position where the rectangular fins are kept arranged up and down in the heat release process.

[0009] Furthermore, a heat insulation device is provided on the outside of the outer tube.

[0010] Furthermore, the phase change material uses mixed nanoparticles.

[0011] Furthermore, a plurality of thermocouples are evenly arranged on the inner wall of the outer tube, and the average value of the temperature of the phase change material collected by all the thermocouples is the average temperature of the phase change material in the melting dead zone.

[0012] Furthermore, all the thermocouples have the same height, and the height difference between the thermocouples and the bottom of the outer tube is the height corresponding to when the volume occupied by the solid phase change material at the bottom of the outer tube reaches a set proportion.

[0013] Furthermore, in the early stage of the heat storage process, the average temperature of the phase change material in the melting dead zone is lower than the solid phase temperature of the phase change material.

[0014] Furthermore, in the later stage of the heat storage process, the average temperature of the phase change material in the melting dead zone is greater than the solid phase temperature of the phase change material, and less than the liquid phase temperature of the phase change material.

[0015] A second aspect of the present invention provides a control method for a high-efficiency phase change heat storage device based on the combined motion of an inner tube as described in the first aspect, comprising the following steps: In the early stage of the heat storage process, the inner tube translation mechanism and the inner tube rotation mechanism are activated to perform a compound motion; In the later stage of the heat storage process, the inner tube rotation mechanism is started to drive the inner tube to rotate to the position where the rectangular fins are kept arranged up and down. Then, the inner tube rotation mechanism is closed and the inner tube translation mechanism is started to drive the inner tube to move closer to the bottom of the outer tube. During the heat release process, the inner tube rotation mechanism is started to drive the inner tube to rotate to the position where the rectangular fins are kept arranged up and down. Then, the inner tube rotation mechanism is closed and the inner tube translation mechanism is started to drive the inner tube to move closer to the top of the outer tube.

[0016] Furthermore, in the later stage of the heat storage process, after the height difference between the bottom of the inner tube and the bottom of the outer tube is less than a first threshold, the inner tube translation mechanism is closed; The first threshold is a multiple of the height difference between the thermocouple and the bottom of the outer tube.

[0017] Furthermore, during the heat release process, after the height difference between the top of the inner tube and the top of the outer tube is less than a second threshold, the inner tube translation mechanism is closed; The second threshold is the height corresponding to when the volume occupied by the liquid phase change material at the top of the outer tube reaches a set proportion.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention describes a high-efficiency phase change heat storage device based on the combined motion of an inner tube. This device is based on a passive reinforcement method that adds rectangular fins and nanoparticles, applies an active reinforcement method that applies inner tube motion, and seeks the optimal combination of the two. This further improves the reinforcement effect while reducing the consumption of phase change material mass and external energy, thus breaking through the reinforcement limits when the active / passive reinforcement methods are used alone.

[0019] The present invention describes a high-efficiency phase-change heat storage device based on the composite motion of an inner tube, which proposes different inner tube motion strategies for the heat storage and heat release processes. For the heat storage process, the inner tube maintains a rotational translational motion state in the early stage. When the melting dead zone appears at the bottom of the phase-change heat storage device, the inner tube moves downward and remains stationary; for the heat release process, the inner tube is placed in the vertical direction of the fins and moves toward the upper part of the phase-change heat storage device, and remains stationary at the upper position of the device; through different inner tube motion strategies, the maximum degree of enhancement of the storage / release rate can be achieved, while reducing the energy consumption caused by the movement of the inner tube and improving economic efficiency.

[0020] The present invention describes a high-efficiency phase-change heat storage device based on the combined motion of an inner tube. Unlike the single rotational and translational motion methods, the inner tube of the phase-change heat storage device with rectangular fins simultaneously rotates and translates, allowing the rectangular fins to enhance heat exchange during the melting and solidification processes of the phase-change material at different longitudinal heights, thereby solving the key technical problems of the original phase-change heat storage device, such as long heat storage / release time and low heat storage / release efficiency, to meet the usage requirements of different heat recovery and utilization scenarios.

[0021] The present invention describes a high-efficiency phase-change heat storage device based on the composite movement of an inner tube. For the heat storage process, corresponding to the process in which the phase-change material changes from liquid to solid, a method for monitoring the movement time of the inner tube is proposed. This monitoring method can timely adjust the movement mode of the inner tube according to the melting condition of the bottom of the phase-change heat storage device. That is, when the movement of the inner tube can no longer further increase the heat storage rate, the movement of the inner tube is stopped. For the heat release process, the same processing method is adopted. When the movement of the inner tube can no longer further increase the heat release rate, the movement of the inner tube is stopped. By setting up automatic control of the inner tube movement, the energy consumption caused by the movement of the inner tube can be further reduced, thereby improving the economy of the phase-change heat storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0023] Figure 1 This is a structural diagram of a high-efficiency phase-change heat storage device based on the composite motion of an inner tube according to Example 1 of the present invention; Figure 2 This is a front view of a high-efficiency phase-change heat storage device based on the combined motion of an inner tube according to Example 1 of the present invention; Figure 3 This is a side view of a high-efficiency phase-change heat storage device based on the composite motion of the inner tube according to Example 1 of the present invention; Figure 4 This is a flow chart of a control method for a high-efficiency phase-change heat storage device based on the compound motion of the inner tube according to Example 2 of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0027] In the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention, and do not specifically refer to any part or element in the present invention, and should not be understood as limiting the present invention.

[0028] In the present invention, terms such as "fixed connection," "connected," and "connection" should be interpreted broadly to mean a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediary. Relevant researchers or technicians in this field may determine the specific meanings of these terms in the present invention based on specific circumstances, and they should not be construed as limitations of the present invention.

[0029] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0030] Example 1 Embodiment 1 of the present invention provides a high-efficiency phase-change heat storage device based on the composite motion of an inner tube.

[0031] At present, there is a lack of research on active and passive synergistic strengthening methods. Most researchers have not yet considered the synergistic effect of the two strengthening methods. By combining the original active and passive strengthening methods and fully considering the respective advantages and disadvantages of the active and passive strengthening methods, it is expected to achieve the degree of reduction in the mass of phase change materials and the minimum external energy consumption, and further break through the strengthening limit when the original strengthening method is used alone.

[0032] This embodiment provides a high-efficiency phase change heat storage device based on the composite motion of the inner tube, such as Figure 1 As shown, it includes an outer tube 1, a heat insulation device 2, an inner tube 3, a phase change material 4, an inner tube translation mechanism 6, an inner tube rotation mechanism 7, a host computer and several thermocouples.

[0033] like Figure 1 As shown, the inner tube 3 is arranged inside the outer tube 1, and the heat insulation device 2 is arranged on the outside of the outer tube 1.

[0034] like Figure 1 As shown, an inner tube translation mechanism 6 and an inner tube rotation mechanism 7 are provided at the ends of the inner tube 3 .

[0035] like Figure 1 and Figure 2 As shown, two rectangular fins 5 are symmetrically provided on the outer side of the inner tube 3 .

[0036] like Figure 1 As shown, the phase change material 4 is filled between the inner tube 3 and the outer tube 1 .

[0037] Among them, several thermocouples are respectively connected to the host computer, and the inner tube translation mechanism 6 and the inner tube rotation mechanism 7 are also respectively connected to the host computer.

[0038] The phase change material 4 is made of mixed nanoparticles.

[0039] The inner tube translation mechanism 6 is used to perform a composite motion with the inner tube rotation mechanism in the early stage of the heat storage process, to drive the inner tube toward the bottom of the outer tube in the late stage of the heat storage process, and to drive the inner tube toward the top of the outer tube in the heat release process; Among them, the inner tube rotation mechanism is used to perform a composite motion with the inner tube translation mechanism in the early stage of the heat storage process, drive the inner tube to rotate to the position where the fins are kept arranged up and down in the later stage of the heat storage process, and drive the inner tube to rotate to the position where the fins are kept arranged up and down in the heat release process.

[0040] In the later stage of the heat storage process, when the height difference between the bottom of the inner tube and the bottom of the outer tube is less than a first threshold, the inner tube translation mechanism is closed. The first threshold is a multiple of the height difference between the thermocouple and the bottom of the outer tube.

[0041] In the later stage of the heat storage process, when the height difference between the bottom of the inner tube and the bottom of the outer tube is less than a second threshold, the inner tube translation mechanism is closed; the second threshold is the height corresponding to when the volume occupied by the liquid phase change material at the top of the outer tube reaches a set proportion.

[0042] Among them, in the early stage of the heat storage process, the average temperature of the phase change material in the melting dead zone is lower than the solid phase temperature of the phase change material.

[0043] In the later stage of the heat storage process, the average temperature of the phase change material in the melting dead zone is greater than the solid phase temperature of the phase change material, and less than the liquid phase temperature of the phase change material.

[0044] When inner tube 3 remains stationary, inner tube rotation mechanism 6 and inner tube translation mechanism 5 remain closed. The two rectangular fins 5 remain vertically positioned to strengthen the melting and solidification dead zones at the bottom and top of inner tube 3. The heat exchange fluid flows into inner tube 3 from the left, exchanges heat with phase change material 4, and then flows out of inner tube 3 from the right.

[0045] When the inner tube 3 performs a combined rotation and translation motion, the inner tube rotation mechanism 5 and the inner tube translation mechanism 6 remain simultaneously powered on. Each mechanism is driven by its own DC motor. At this point, the inner tube 3 performs a combined rotation and translation motion, with its translation and rotation motions independently controlled, allowing the inner tube 3 to reciprocate and rotate within a defined range of motion at defined translational and rotational speeds. The heat exchange fluid enters from the left side, exchanges heat with the phase change material 4, and then exits from the right side. Once the phase change material 4 is observed to be completely melted, the DC power supply and the inner tube rotation mechanism 5 or inner tube translation mechanism 6 are turned off.

[0046] For the heat storage process, the phase change material 4 melts from the solid phase to the liquid phase. As the heat storage process proceeds, the melting dead zone gathers at the bottom of the phase change heat storage device. At this time, if the inner tube 3 remains in motion, it will periodically pass through the bottom of the heat storage device, and the strengthening effect will be significantly reduced. If the inner tube 3 is stationary at a certain position at the bottom of the outer tube 1 in the later stage of the melting process, the melting rate will be further increased. At the same time, the inner tube 3 will no longer need to remain in motion, reducing the external energy consumption caused by the movement of the inner tube 3.

[0047] like Figure 2 and Figure 3 As shown, four different thermocouples are evenly arranged on the inner wall of the outer tube 1: the first thermocouple A, the second thermocouple B, the third thermocouple C, and the fourth thermocouple D. The height difference between the four different thermocouples and the bottom of the outer tube 1 is X ,in, X The corresponding height is when the phase change material of the heat storage device has melted 95%, that is, when the solid phase change material at the bottom accounts for 5% of the set volume. At this time, the phase change material area in the bottom region accounts for 5% of the area of ​​the ring. The first thermocouple A and the second thermocouple B are symmetrically arranged on the same cross-section of the outer tube 1. The third thermocouple C and the fourth thermocouple D are symmetrically arranged on the same cross-section of the outer tube 1.

[0048] The temperatures (temperature signals) of the phase change material collected by the first thermocouple A, the second thermocouple B, the third thermocouple C and the fourth thermocouple D are T A 、T B 、T C 、T D , then the average temperature of the phase change material in the melting dead zone is T X for:

[0049] Then, the average temperature T of the phase change material in the melting dead zone is X The solid / liquid phase temperature T of the phase change material s 、T lFor comparison, when T s <T X <T l When the phase change material is melted into liquid, it means that the volume of the phase change material is about 95% of the total volume (according to the above definition, X The area of ​​the phase change material corresponding to the height is 5%). At this time, if the inner tube continues to move, the fins will periodically pass through the remaining solid phase change material area at the bottom. Therefore, compared with the fins placed vertically and kept stationary, the continued movement of the inner tube will significantly reduce the heat storage rate. Therefore, when T s <T X <T l When the inner tube rotation mechanism 7 is controlled to be closed, the inner tube translation mechanism 6 is started, and the inner tube 3 moves downward for a distance. When the distance between the bottom of the fin and the outer shell is the first threshold value 0.2 X When the heat storage process is complete, the fins are kept in an up-and-down arrangement and stationary, thereby achieving a higher heat transfer rate in the later stage of the heat storage process.

[0050] The heat release process corresponds to the solidification process in which the phase change material 4 changes from liquid to solid. As the process progresses, the solid phase change material 4 around the inner tube 3 will gradually increase, resulting in increasing resistance to the movement of the inner tube 3. Therefore, to ensure the safety of the movement process, the inner tube 3 must remain stationary throughout the heat release process. In addition, for the stationary inner tube 3, the upper area of ​​the heat storage device corresponds to the solidification dead zone, where the phase change material 4 solidifies last. Therefore, when the fins are arranged vertically and the inner tube 3 is arranged eccentrically upward, the heat release process is more effective.

[0051] Therefore, when the heat release process begins, the fins are kept arranged up and down, and the inner tube 3 is translated upward by the inner tube translation mechanism 6, defining the second threshold value. Y , and the height difference between the thermocouple and the bottom of the outer tube 1 X Similar, high Y The height of the phase change material corresponds to the time when the liquid phase change material area in the top area accounts for 5% of the entire ring area. Move the inner tube upward until the distance between the fin end point and the shell is 0.2 Y After reaching this position, the inner tube 3 remains stationary and performs the next heat release process. At this time, the external energy consumed by the movement of the inner tube 3 will no longer be consumed. At the same time, it ensures that the solid phase change material gradually increasing during the heat release process will not affect the inner tube 3 and damage its mechanical structure.

[0052] This embodiment proposes a synergistic coupling of active and passive reinforcement technologies. By improving the smooth inner tube, a phase change heat storage device with rectangular fins and a hybrid nanoparticle phase change material is proposed. Based on the passive reinforcement method of adding nanoparticles, the active reinforcement method of inner tube movement is applied. The optimal combination of the two is then sought to further enhance the reinforcement effect while reducing the consumption of phase change material mass and external energy, thus surpassing the reinforcement limits of active and passive reinforcement methods used alone.

[0053] This embodiment proposes a combined rotational and translational motion of the inner tube. Unlike rotational and translational motion alone, the inner tube of the phase-change heat storage device with rectangular fins undergoes simultaneous rotational and translational motion. This allows the rectangular fins to enhance heat transfer during the melting and solidification processes of the phase-change material at different longitudinal heights. This addresses the key technical issues of the long heat storage and release times and low heat storage and release efficiencies of existing phase-change heat storage devices, meeting the requirements of various heat recovery and utilization scenarios.

[0054] This embodiment proposes a method for monitoring the inner tube movement time. For the heat storage process, corresponding to the phase change material changing from liquid to solid phase, a method for monitoring the inner tube movement time is proposed. This monitoring method can timely adjust the movement mode of the inner tube according to the melting condition of the bottom of the phase change heat storage device. That is, when the movement of the inner tube can no longer further increase the heat storage rate, the inner tube movement is stopped. For the heat release process, the same processing method is adopted. When the movement of the inner tube can no longer further increase the heat release rate, the inner tube movement is stopped. By setting up automatic control of the inner tube movement, the energy consumption caused by the inner tube movement can be further reduced, and the economic efficiency of the phase change heat storage device can be improved.

[0055] This embodiment proposes different inner tube movement strategies for both the heat storage and heat release processes, focusing on the inner tube's movement mode. For the heat storage process, the inner tube maintains a rotational translational motion state in the early stages. When the melting dead zone appears at the bottom of the phase change heat storage device, the inner tube moves downward and remains stationary. For the heat release process, before the heat release process begins, the inner tube is placed with its fins vertically aligned and moved toward the top of the phase change heat storage device, remaining stationary at the top. Through these different inner tube movement strategies, the maximum possible heat storage and release rate can be achieved while reducing energy consumption caused by inner tube movement and improving the system's economic efficiency.

[0056] Example 2 Example 2 of the present invention provides a control method for a high-efficiency phase change heat storage device based on the composite motion of the inner tube as in Example 1, such as Figure 4 As shown, the following steps are included: Step 1: For the heat storage process, the host computer controls the inner tube translation mechanism 6 and the inner tube rotation mechanism 7 to start, and the inner tube 3 performs a composite motion of rotation and translation. The heat exchange fluid flows into the inner tube 3 from the left, and after heat exchange with the phase change material 4, the heat exchange fluid flows out of the inner tube 3 from the right; the host computer sends a thermocouple temperature acquisition signal to control the four different thermocouples (first thermocouple A, second thermocouple B, third thermocouple C, fourth thermocouple D) evenly arranged on the inner wall of the outer tube 1 to start. The temperatures (temperature signals) of the phase change materials collected by the four different thermocouples (first thermocouple A, second thermocouple B, third thermocouple C, fourth thermocouple D) are T A 、T B 、T C 、T D , uploaded to the host computer, the host computer processes the temperature signal and calculates the average temperature T of the phase change material in the melting dead zone X : ; Then, the host computer will melt the average temperature T of the dead zone phase change material X The solid / liquid phase temperature T of the phase change material s 、T l For comparison, when T s <T X <T l , which means that if the inner tube continues to move, the heat storage rate will be significantly reduced. Therefore, when T s <T X <T l When the upper position controls the inner tube rotation mechanism 7 to close, the inner tube translation mechanism 6 is started, and the inner tube 3 moves downward for a distance, so that the height difference between the bottom of the inner tube 3 and the bottom of the outer tube 1 is 0.2 X ,After reaching this position, the fins remain arranged up and down, keeping the inner tube 3 stationary, thereby achieving a higher heat transfer rate in the later stage of the heat storage process.

[0057] Step 1: For the heat release process, after controlling the inner tube rotation mechanism 7 to keep the fins arranged up and down, the upper computer controls the inner tube translation mechanism 6 to start and the inner tube rotation mechanism 7 to close, and translate the inner tube 3 upward. At this time, the distance between the top of the inner tube and the top of the outer tube is Y ,in Y The second threshold corresponds to the height of the phase change material when the area of ​​the liquid phase change material in the top region accounts for 5% of the area of ​​the entire circular ring. After reaching this position, the upper position controls the inner tube translation mechanism 6 and the inner tube rotation mechanism 7 to close, and the inner tube 3 remains stationary for the next heat release process. At this time, the external energy consumed by the movement of the inner tube 3 will no longer be consumed. At the same time, it ensures that the solid phase change material gradually increasing during the heat release process will not affect the inner tube 3 and damage its mechanical structure.

[0058] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A high-efficiency phase change heat storage device based on the composite motion of the inner tube, characterized in that: The invention comprises an outer tube, an inner tube arranged inside the outer tube, an inner tube translation mechanism and an inner tube rotation mechanism arranged at the end of the inner tube, and a phase change material filled between the inner tube and the outer tube, and two rectangular fins are symmetrically arranged on the outer side of the inner tube; The inner tube translation mechanism is used to perform a composite motion with the inner tube rotation mechanism in the early stage of the heat storage process, drive the inner tube closer to the bottom of the outer tube in the late stage of the heat storage process, and drive the inner tube closer to the top of the outer tube in the heat release process; The inner tube rotation mechanism is used to perform a composite motion with the inner tube translation mechanism in the early stage of the heat storage process, drive the inner tube to rotate to a position where the rectangular fins are kept arranged up and down in the late stage of the heat storage process, and drive the inner tube to rotate to a position where the rectangular fins are kept arranged up and down in the heat release process.

2. The high-efficiency phase change heat storage device based on the composite motion of the inner tube according to claim 1, characterized in that: A heat insulation device is provided on the outside of the outer tube.

3. The high-efficiency phase change heat storage device based on the composite motion of the inner tube according to claim 1, characterized in that: The phase change material adopts mixed nanoparticles.

4. The high-efficiency phase change heat storage device based on the composite motion of the inner tube according to claim 1, characterized in that: A plurality of thermocouples are evenly arranged on the inner wall of the outer tube, and the average value of the temperature of the phase change material collected by all the thermocouples is the average temperature of the phase change material in the melting dead zone.

5. The high-efficiency phase change heat storage device based on the composite motion of the inner tube according to claim 4, characterized in that: All thermocouples have the same height, and the height difference between the thermocouple and the bottom of the outer tube is the height corresponding to when the volume occupied by the solid phase change material at the bottom of the outer tube reaches a set proportion.

6. The high-efficiency phase change heat storage device based on the composite motion of the inner tube according to claim 1, characterized in that: In the early stage of the heat storage process, the average temperature of the phase change material in the melting dead zone is lower than the solid phase temperature of the phase change material.

7. The high-efficiency phase change heat storage device based on the composite motion of the inner tube according to claim 1, characterized in that: In the later stage of the heat storage process, the average temperature of the phase change material in the melting dead zone is greater than the solid phase temperature of the phase change material, and less than the liquid phase temperature of the phase change material.

8. A control method for a high-efficiency phase-change heat storage device based on the combined motion of an inner tube according to any one of claims 1 to 7, characterized in that: include: In the early stage of the heat storage process, the inner tube translation mechanism and the inner tube rotation mechanism are activated to perform a compound motion; In the later stage of the heat storage process, the inner tube rotation mechanism is started to drive the inner tube to rotate to the position where the rectangular fins are kept arranged up and down. Then, the inner tube rotation mechanism is closed and the inner tube translation mechanism is started to drive the inner tube to move closer to the bottom of the outer tube. During the heat release process, the inner tube rotation mechanism is started to drive the inner tube to rotate to the position where the rectangular fins are kept arranged up and down. Then, the inner tube rotation mechanism is closed and the inner tube translation mechanism is started to drive the inner tube to move closer to the top of the outer tube.

9. A control method for a high-efficiency phase-change heat storage device based on the combined motion of an inner tube according to claim 8, characterized in that: In the later stage of the heat storage process, after the height difference between the bottom of the inner tube and the bottom of the outer tube is less than a first threshold, the inner tube translation mechanism is closed; The first threshold is a multiple of the height difference between the thermocouple and the bottom of the outer tube.

10. The control method of the high-efficiency phase change heat storage device based on the composite motion of the inner tube according to claim 8, characterized in that: During the heat release process, after the height difference between the top of the inner tube and the top of the outer tube is less than a second threshold, the inner tube translation mechanism is closed; The second threshold is the height corresponding to when the volume occupied by the liquid phase change material at the top of the outer tube reaches a set proportion.

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