Cold storage dewar device with anisotropic thermal conductivity

Abstract

Disclosed in the present invention is a cold storage dewar device with anisotropic thermal conductivity. The cold storage dewar device comprises cold storage dewars and an axial pipe penetrating through the cold storage dewars, wherein the cold storage dewars comprise a main cold storage dewar and a plurality of small cold storage dewars which are axially connected in series. Solid mediums are accumulated in a dewar space between the inner wall of each cold storage dewar and the outer wall of the pipe, and room-temperature or cryogenic high-pressure air enters, in an opposite direction, a pipe space inside the pipe, and exchanges cold energy with the solid mediums by means of the pipe wall of the pipe; and adiabatic valves for separating the dewar spaces between the small cold storage dewars are provided along the pipe. Inside the main cold storage dewar, the axial thermal conductivity of the solid mediums is lower than the radial thermal conductivity thereof, the axial thermal conductivity of the pipe is lower than the radial thermal conductivity thereof, and the axial thermal conductivity of the solid mediums is close to or higher than the axial thermal conductivity of the pipe. The advantages of the present invention lie in that during cold storage and cold release processes and in a standing state without cold storage and cold release, a temperature difference of cold energy exchange and the loss of useful work are effectively reduced.

Description

A cold tank device with anisotropic thermal conductivity

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. CN202311680542.3 filed on December 8, 2023. The full text of the above-mentioned Chinese patent application is hereby cited as part of this application. Technical Field

[0003] The present invention relates to the field of cold energy storage and release devices, and in particular to a cold tank device with anisotropic thermal conductivity. Background Art

[0004] Cold storage and release devices using solid media rely primarily on the sensible heat storage capacity of solid materials, storing and releasing cold energy by changing the temperature of the solid medium. Solid media can be made of materials with high specific heat capacity and high thermal conductivity, such as graphene, metal oxides, or specialized ceramics. Alternatively, less expensive materials such as pebbles, basalt, and volcanic rocks can be used. The solid media is placed in an insulated cold tank to minimize cold energy loss and maintain efficient cold energy storage and release. This system is particularly suitable for applications requiring large amounts of cold energy storage and temperature control, such as building temperature control or industrial process cooling.

[0005] When the cooling fluid is high-pressure air, a solid medium pipe can be used to prevent the cold tank from reaching a high pressure. During cold release, room-temperature high-pressure air is introduced into the pipe, absorbing cold energy from the solid medium through the pipe wall. During cold storage, deep-cold high-pressure air is introduced into the pipe from the opposite direction, releasing cold energy to the solid medium through the pipe wall, which is typically made of metal. This design makes it difficult to form a complete and smooth oblique temperature layer within the solid medium. Migration of the oblique temperature layer outside the tank will affect the input and output parameters of the cold tank, while retaining the oblique temperature layer within the tank will result in temperature convergence during static conditions. These drawbacks affect the efficiency of the cold tank's cold storage and release.

[0006] The features and challenges of the prior art are described in detail below.

[0007] The formation of a thermocline. For example, a solid medium bed filled with pebbles as a storage medium can be used to store cold energy. The concept of a thermocline is fundamental to understanding how these systems work. The unit has an inlet and outlet, allowing ambient air to flow through the pebble bed. Cold storage: When storing cold energy, cryogenic air is introduced from the bottom of the container. As the cryogenic air moves upward, it transfers its "cold energy" to the pebbles, effectively cooling them. Since the bottom layer of pebbles first comes into contact with the cryogenic air, they are cooled first. As the cryogenic air moves upward, it transfers its coldness to the pebbles, gradually warming them. This creates a temperature gradient, with the coldest pebbles at the bottom and the temperature gradually decreasing from bottom to top. This temperature difference is called a thermocline. Cold release: When releasing cold energy, ambient air is introduced from the top of the container. As the ambient air moves downward, it absorbs "cold energy" from the pebbles, effectively cooling the ambient air. The top layer of pebbles first transfers its "cold energy" to the ambient air. As the ambient air moves downward, it gradually cools, retrieving the cold energy stored in the pebbles. Once again, a similar thermocline layer forms within the container. After flowing through the entire cooled pebble bed, the coldest pebbles remain at the bottom. A complete and smooth thermocline layer is advantageous because it serves as an indicator of the state of stored energy and the location of cooling. A complete and smooth thermocline layer indicates a clear separation between hot and cold areas of storage. By monitoring and managing the thermocline layer, the performance of the solid media packed bed can be optimized.

[0008] The dissipation of the thermocline layer. The dissipation of the thermocline layer during the system's static time will lead to The loss of heat is significant. Once a thermocline forms and the system stops operating (i.e., no cold storage or release occurs), several phenomena may occur, leading to its dissipation: 1) Thermal diffusion: Even without active flow, heat naturally diffuses from warmer to cooler areas. Therefore, over time, the thermocline will become less pronounced. The temperature within the pebble bed will gradually reach equilibrium, causing the thermocline to diffuse or dissipate. 2) Natural convection: Even without active fluid pumping into the bed, temperature differences induce buoyancy-driven fluid motion. Warmer fluid tends to rise, while cooler fluid tends to sink. This natural convection can disrupt the thermocline, causing fluid mixing and further reducing the temperature gradient. 3) Interpebble conduction: Pebbles themselves can conduct heat. This means that, due to the presence of the thermocline, adjacent pebbles will have different temperatures and will exchange heat. Cooler pebbles will absorb heat from warmer ones, again causing the thermocline to diffuse and become less pronounced.

[0009] Indirect cooling. Indirect cooling involves a flow of ambient temperature or cryogenically cooled, high-pressure air through a cold tank within a pipeline, exchanging cold energy with the solid medium through the pipe wall. Indirect cooling presents many challenges, including the cold energy transfer area. To increase the efficiency of cold energy exchange, sufficient area must be provided for cold energy transfer. Cooling between the pipeline and the solid medium is essentially solid-to-solid cooling, which has structural limitations on the cooling area. Furthermore, the temperature gradient generated during the cooling process between the pipeline and the solid medium can also introduce significant complexity.

[0010] To illustrate this using the simplest design: Imagine a pipe running through a cold storage tank along the central axis of the tank; the outer wall of the pipe exchanges cold energy with the solid medium. In this case, the temperature distribution within the solid medium will not be uniform. First, the area of ​​the solid medium in direct contact with the outer wall of the pipe will typically experience the greatest temperature change. During a cooling process, this area will be the coldest; during a heating process, it will be the hottest. As the distance from the pipe increases, the temperature change in areas further away from the pipe wall gradually decreases, forming a radial thermocline layer—a temperature gradient—from the pipe wall to the inner wall of the tank.

[0011] At the same time, because the cooling fluid flows along the axial direction of the cold tank, a temperature oblique layer - the axial temperature oblique layer - will also be formed along the axial direction of the tank body; with the cooling process, the temperature oblique layer changes continuously; with the repeated cycles of cold storage and release, the evolution of the temperature oblique layer will be quite complicated, seriously affecting the efficiency of cold storage and release.

[0012] In practical applications of cold tank devices, it is sometimes necessary to ensure the cyclical stability of the inlet and outlet temperatures of the cold tank. If the temperature gradient shifts beyond the limit of the cold tank, the inlet and outlet temperatures of the cold tank will change significantly, resulting in abnormal system operation.

[0013] Another factor exacerbates the complexity of the thermocline: pipelines are typically made of metal, which has a higher thermal conductivity than non-metallic solid media. The rapid exchange of cold energy along the pipeline further complicates the radial and axial thermoclines within the solid media. Summary of the Invention

[0014] The technical problem to be solved by the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a cold tank device with anisotropic thermal conductivity.

[0015] According to an embodiment of the present invention, a cold tank device with anisotropic thermal conductivity includes: a cold tank and an axially extending pipeline extending through the cold tank, the cold tank comprising a main cold tank and a plurality of small cold tanks connected in series. A solid medium is deposited within the tank space between the inner wall of the cold tank and the outer wall of the pipeline. Normal temperature or cryogenic high-pressure air enters the pipeline space within the pipeline from opposite directions, exchanging cold energy with the solid medium through the pipeline wall. Thermal insulation is provided along the pipeline to separate the tank space between the small cold tanks.

[0016] Among them, the radial and axial directions of the main cold tank are used as judgment criteria. Inside the main cold tank, the axial thermal conductivity of the solid medium is lower than its radial thermal conductivity, the axial thermal conductivity of the pipeline is lower than its radial thermal conductivity, and the axial thermal conductivity of the solid medium is close to or higher than the axial thermal conductivity of the pipeline; through such selection of thermal conductivity, during the cold storage or release process, the radial temperature of the solid medium is converged, and a temperature oblique layer distributed along the axial direction of the solid medium is achieved.

[0017] In which, during the cold storage or release process, the temperature oblique layer migrates from the main cold tank to the multiple small cold tanks; after the cold storage or release process is completed, the insulation is closed, and the temperature oblique layer converts the temperature gradient between the multiple small cold tanks; when the cold storage or release process begins, the temperature gradient is converted into the temperature oblique layer in the main cold tank.

[0018] According to an embodiment provided by the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that a plurality of small cold tanks form a normal temperature end inclined temperature layer storage unit at the normal temperature end of the main cold tank; at the end of the cold storage stage, the inclined temperature layer completely enters the normal temperature end inclined temperature layer storage unit from the main cold tank.

[0019] According to an embodiment provided by the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that a plurality of small cold tanks form a deep cold end inclined temperature layer storage unit at the deep cold end of the main cold tank; at the end of the cold release stage, the inclined temperature layer completely enters the deep cold end inclined temperature layer storage unit from the main cold tank.

[0020] According to an embodiment of the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that, inside the small cold tank, the radial thermal conductivity of the pipeline and the thermal conductivity of the solid medium are both higher than the axial thermal conductivity of the pipeline.

[0021] According to an embodiment provided by the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that the pipeline that does not directly contact the solid medium is made of an insulating material.

[0022] According to an embodiment provided by the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that, inside the main cold tank, a solid medium with higher isotropic thermal conductivity and a solid medium with lower isotropic thermal conductivity are selected, and the average axial thermal conductivity of the solid medium is lower than its average radial thermal conductivity through the spatial distribution of the two solid media in the main cold tank.

[0023] According to an embodiment provided by the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that the solid medium with isotropic thermal conductivity is selected from a first medium group, and the first medium group selects one or more of metal, carbon black, volcanic rock, basalt, conglomerate, sandstone, pebbles or quartz stone.

[0024] According to an embodiment provided by the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that the solid medium is selected from a solid medium with anisotropic thermal conductivity, and the solid medium with anisotropic thermal conductivity is selected from a second medium group, and the second medium group is selected from one or more of graphite, graphene, carbon fiber reinforced plastic or metal fiber reinforced polymer composite materials.

[0025] According to an embodiment provided by the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that the material of the pipeline includes multiple layers of carbon fiber reinforced polymer material and interlayers between carbon fiber layers, higher density carbon fibers are arranged in the direction where higher thermal conductivity is required, and lower density carbon fibers are arranged in the direction where lower thermal conductivity is required, and metal powder or graphite powder is added in the interlayer without carbon fiber layers to improve the thermal conductivity of the interlayer through the pipe wall of the pipeline.

[0026] According to an embodiment provided by the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that the material of the pipeline includes a material with higher thermal conductivity and a material with lower thermal conductivity, and more materials with higher thermal conductivity are arranged in the direction where higher thermal conductivity is required.

[0027] According to an embodiment of the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that the pipeline inside the main cold tank or the small cold tank is a parallel tube bundle composed of multiple pipelines parallel to the axis of the cold tank.

[0028] According to an embodiment of the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that the number of the main cold tanks is one or more, wherein the multiple main cold tanks are connected in axial series or in parallel.

[0029] According to an embodiment of the present invention, a cold tank device with anisotropic thermal conductivity is provided, characterized in that the multiple small cold tanks are a connected tank body, and the tank space within the connected tank body is separated by the insulating valve.

[0030] According to an embodiment of the present invention, a cold tank device with anisotropic thermal conductivity is characterized in that the insulating valve isolates the tank space between the cold tanks while also isolating the pipeline space of the pipeline between the cold tanks.

[0031] Compared with the prior art, the cold tank device with anisotropic thermal conductivity provided by the present invention has the following advantages:

[0032] 1. By using pipelines for indirect cold exchange, the cold tanks do not need to withstand high pressure; using normal-pressure insulated containers can meet system requirements. Therefore, during cold storage or release, internal connectivity between the tanks and thermal insulation between the tanks and the surrounding environment are more easily achieved. In a static state, when no cold is being stored or released, thermal insulation between the tanks and between the tanks and the surrounding environment is also more easily achieved. Compared to existing technologies, in the deep-freeze range, thermal insulation between the cold tanks in series is difficult to achieve.

[0033] 2. By using materials and / or processes with thermodynamically anisotropic characteristics, the thermal conductivity along the radial direction of the tank body is generally higher than the thermal conductivity along the axial direction of the tank body during the exchange of cold energy between high-pressure air and the solid medium, thereby realizing a clearly structured thermocline layer within the solid medium and achieving complete axial migration of the thermocline layer along the tank body. The advantage is that the temperature difference in cold energy exchange is effectively reduced, thereby reducing the loss of cold energy.

[0034] 3. At the end of cold storage and release, a thermocline layer must be maintained within the cold tank to maintain consistent inlet and outlet temperatures. A thermocline layer protection unit, comprised of several small cold tanks, can transform the thermocline layer into a temperature gradient between the several small cold tanks within the unit. Although the temperatures within each small cold tank will converge when the unit is stationary without cold storage or release, the thermocline layer is still maintained as a temperature gradient between the multiple small cold tanks. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] FIG1 is a schematic structural diagram of a cold tank device in one embodiment of the present invention;

[0037] FIG2 is a schematic diagram showing the thermal conductivity of the main cooling tank in one embodiment of the present invention.

[0038] FIG. 3 a is a schematic diagram of the axial temperature of a main cold tank device according to an embodiment of the present invention.

[0039] FIG3 b is a schematic diagram of the axial temperature of a main cold tank device according to an embodiment of the present invention.

[0040] FIG4 a is a first exploded perspective view of a pipeline in one embodiment of the present invention.

[0041] FIG4 b is a second exploded perspective view of a pipeline in one embodiment of the present invention.

[0042] FIG4 c is a third exploded perspective view of a pipeline in one embodiment of the present invention.

[0043] FIG. 5 is another exploded perspective view of a pipeline in one embodiment of the present invention.

[0044] FIG6 is a schematic diagram showing the state of the normal temperature end temperature cline layer in one embodiment of the present invention.

[0045] FIG7 is a schematic diagram of the migration process of the constant temperature end temperature cline layer in one embodiment of the present invention.

[0046] FIG8 is a schematic diagram of a state after migration of the normal temperature end temperature cline layer in one embodiment of the present invention.

[0047] FIG9 is a schematic diagram of the state of the deep cold end thermocline layer in one embodiment of the present invention.

[0048] FIG10 is a schematic diagram of the migration process of the deep cold end thermocline layer in one embodiment of the present invention.

[0049] FIG11 is a schematic diagram of a pipeline structure in an embodiment of the present invention.

[0050] To facilitate search and comparison, the components in the accompanying drawings are named according to the following English abbreviation rules:

[0051] MCD: Main Cold Storage Dewar, main cold tank

[0052] MCD-M:Main Cold Storage Dewar Solid Medium, solid medium in the main cold tank

[0053] SD-M:Small Cold Storage Dewar Solid Medium, solid medium in small cold tank

[0054] PP:Pipe, pipeline

[0055] SD: Small Cold Storage Dewar, small cold tank, including: SD1, the first small cold tank; SD2, the second small cold tank; SD3, the third small cold tank; SD4, the fourth small cold tank; SD5, the fifth small cold tank; SD6, the sixth small cold tank; SD7, the seventh small cold tank; SD8, the eighth small cold tank; SD9, the ninth small cold tank; SD10, the tenth small cold tank.

[0056] V: Adiabatic Valve, adiabatic valve, including: V1, the first adiabatic valve; V2, the second adiabatic valve; V3, the third adiabatic valve; V4, the fourth adiabatic valve; V5, the fifth adiabatic valve; V6, the sixth adiabatic valve; V7, the seventh adiabatic valve; V8, the eighth adiabatic valve; V9, the ninth adiabatic valve; V10, the tenth adiabatic valve; V11, the eleventh adiabatic valve; V12, the twelfth adiabatic valve.

[0057] APU: Ambient-Side Thermocline Preservation Unit, ambient temperature end thermostatic layer preservation unit

[0058] CPU: Cryogenic-Side Thermocline Preservation Unit, deep cold side thermocline layer preservation unit

[0059] Kr:Radial Thermal Conductivity, radial thermal conductivity

[0060] Ka:Axial Thermal Conductivity, axial thermal conductivity

[0061] Ktt:Through Thickness Thermal Conductivity, insulation thermal conductivity DETAILED DESCRIPTION

[0062] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It will be understood that the specific embodiments described herein are intended only to illustrate the relevant content and are not intended to limit the present invention. It should also be noted that, for ease of description, only portions relevant to the present invention are shown in the accompanying drawings.

[0063] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0064] Unless otherwise stated, the exemplary embodiments / examples shown are to be understood as providing exemplary features of various details of some ways in which the technical concept of the present invention can be implemented in practice. Therefore, unless otherwise stated, the features of the various embodiments / examples may be further combined, separated, interchanged, and / or rearranged without departing from the technical concept of the present invention.

[0065] Referring to FIG. 1 , according to one embodiment of the present invention, a cold tank device with anisotropic thermal conductivity includes a cold tank comprising a main cold tank (MCD) and multiple small cold tanks connected axially in series. The multiple small cold tanks include a first small cold tank SD1, a second small cold tank SD2, a third small cold tank SD3, a fourth small cold tank SD4, a fifth small cold tank SD5, a sixth small cold tank SD6, a seventh small cold tank SD7, an eighth small cold tank SD8, a ninth small cold tank SD9, and a tenth small cold tank SD10. The cold tanks (including the main cold tank MCD and the small cold tanks SD) have a pipeline PP extending axially through the interior of the cold tanks. High-pressure air, either at room temperature or cryogenically, flows within the pipeline space within the pipeline PP. A normal-pressure tank space is defined between the inner wall of the cold tanks (including the main cold tank MCD and the small cold tanks SD) and the outer wall of the pipeline PP. This tank space houses the solid medium MCD-M within the main cold tank and the solid medium SD-M within the small cold tanks. Adiabatic valves are provided along the pipeline PP, including a first adiabatic valve V1, a second adiabatic valve V2, a third adiabatic valve V3, a fourth adiabatic valve V4, a fifth adiabatic valve V5, a sixth adiabatic valve V6, a seventh adiabatic valve V7, an eighth adiabatic valve V8, a ninth adiabatic valve V9, a tenth adiabatic valve V10, an eleventh adiabatic valve V11, and a twelfth adiabatic valve V12. The adiabatic valves isolate the tank spaces between the main cold tank MCD and the small cold tank SD.

[0066] Referring to Figure 2 , according to one embodiment of the present invention, the main cold tank MCD has two inlet and outlet ports: a room temperature end ATE and a deep cold end CTE. The pipeline PP enters from one port and exits from the other. The present invention defines the pipeline PP along the central axis of the main cold tank MCD, thereby defining the axial direction and the axial thermal conductivity Ka of the pipeline PP. The direction perpendicular to the axial direction is defined as the radial direction, thereby defining the radial thermal conductivity Kr of the pipeline PP. The thermal conductivity of the cold energy exchange perpendicular to and through the pipe wall of the pipeline PP is defined as the interlayer thermal conductivity Ktt. Of course, in different embodiments, the pipeline PP has different structures, such as a spiral coil structure. Therefore, the axial direction in the present invention is based on the overall flow direction of the cold exchange fluid in the main cold tank MCD, and the direction perpendicular to the flow direction of the cold exchange fluid is defined as the radial direction. The radial thermal conductivity Kr and axial thermal conductivity Ka of the solid medium MCD-M within the main cold tank can also be defined similarly as shown in Figure 2 .

[0067] Referring to Figures 1 and 2 , according to one embodiment of the present invention, using the radial and axial directions of the main cooling tank MCD as criteria, within the main cooling tank MCD, the axial thermal conductivity Ka of the solid medium MCD-M within the main cooling tank is lower than its radial thermal conductivity Kr, the axial thermal conductivity Ka of the pipeline PP is lower than its radial thermal conductivity Kr, and the axial thermal conductivity Ka of the solid medium MCD-M within the main cooling tank is equal to or higher than the axial thermal conductivity Ka of the pipeline PP. A high-pressure cooling fluid, such as high-pressure air, flows within the space of the pipeline PP. When high-pressure air enters pipeline PP, it exchanges cold energy with the solid medium through pipeline PP. Since the axial thermal conductivity Ka of the solid medium MCD-M in the main cold tank is lower than its radial thermal conductivity Kr and is equal to or higher than the axial thermal conductivity Ka of the pipeline PP, and the axial thermal conductivity Ka of the pipeline PP is close to or lower than its radial thermal conductivity Kr, the high-pressure air and the solid medium complete the cold energy exchange in the radial direction more fully and quickly. The radial cold energy exchange is completed more quickly than the axial cold energy exchange, which promotes the formation of a complete and smooth oblique temperature layer.

[0068] Referring to Figure 1, by selecting the various thermal conductivities, a complete and smooth thermocline layer is formed along the axis of the main cooling tank MCD within the solid medium MCD-M during the cold storage and release processes. In practical applications, the choice of cooling fluid, its pressure and flow rate, and the choice of solid medium and piping materials all influence the state of the thermocline layer, requiring comprehensive design to ultimately achieve the desired thermocline layer formation.

[0069] According to one embodiment of the present invention, during the cold storage or release process, the temperature oblique layer migrates from the main cold tank MCD to the multiple small cold tanks; after the cold storage or release process is completed, the cold tank device is in a static state, the adiabatic valve is closed, and the temperature oblique layer converts the temperature gradient between the multiple small cold tanks; when the cold storage or release process begins, the temperature gradient is converted into the temperature oblique layer in the main cold tank MCD.

[0070] Referring to Figure 1, according to one embodiment of the present invention, multiple small cold tanks form a thermocline layer storage unit. At the end of cold storage or release, the thermocline layer fully enters the thermocline layer storage unit. After cold storage or release, the adiabatic valve closes, the temperatures within the small cold tanks gradually converge, and the thermocline layer transforms into a temperature gradient between the multiple small cold tanks within the thermocline layer storage unit.

[0071] Referring to Figure 1, according to one embodiment of the present invention, multiple small cold tanks, namely the first small cold tank SD1, the second small cold tank SD2, the third small cold tank SD3, the fourth small cold tank SD4, and the fifth small cold tank SD5, form an ambient temperature side temperature storage unit (APU) at the ambient temperature side of the main cold tank MCD. Multiple small cold tanks, namely the sixth small cold tank SD6, the seventh small cold tank SD7, the eighth small cold tank SD8, the ninth small cold tank SD9, and the tenth small cold tank SD10, form a cryogenic side temperature storage unit (CPU) at the cryogenic side of the main cold tank MCD. In this embodiment, the inlet and outlet ends of the first through fifth small cold tanks SD1 through SD5 are respectively provided with first through sixth adiabatic valves V1 through V6, while the inlet and outlet ends of the sixth through tenth small cold tanks SD6 through SD10 are respectively provided with seventh through twelfth adiabatic valves V7 through V12. These adiabatic valves are used to isolate the tank spaces between the small cold tanks, preventing cold energy from migrating between them.

[0072] Referring to Figure 1, according to one embodiment of the present invention, during the cold storage stage, cryogenic high-pressure air sequentially enters the pipeline PP space of the cryogenic end temperature-cline layer storage unit CPU, the main cold tank MCD, and the normal temperature end temperature-cline layer storage unit APU. First, the temperature gradient of the cryogenic end temperature-cline layer storage unit CPU is converted into the temperature-cline layer within the main cold tank MCD; then, the temperature-cline layer translates within the main cold tank MCD; finally, the temperature-cline layer completely enters the normal temperature end temperature-cline layer storage unit APU, completing the cold storage stage.

[0073] Referring to FIG. 1 , according to one embodiment of the present invention, after cold storage ends and before cold release begins, the cold tank device is in a stationary state, the adiabatic valve is closed, the temperatures of the solid media SD-M in the multiple small cold tanks converge, and the temperature gradient in the normal temperature end temperature gradient storage unit APU is converted into a temperature gradient between the multiple small cold tanks in the normal temperature end temperature gradient storage unit APU.

[0074] Referring to Figure 1, according to one embodiment of the present invention, during the cooling stage, normal temperature high-pressure air sequentially enters the pipeline PP space of the normal temperature end thermocline layer storage unit APU, the main cold tank MCD, and the deep cold end thermocline layer storage unit CPU. First, the temperature gradient of the normal temperature end thermocline layer storage unit is converted into the thermocline layer within the main cold tank MCD; then, the thermocline layer translates within the main cold tank MCD; finally, the thermocline layer completely enters the deep cold thermocline layer storage unit CPU, completing the cooling stage.

[0075] Referring to FIG. 1 , according to one embodiment of the present invention, after the cold release is completed and before the cold storage begins, the cold tank device is in a stationary state, the adiabatic valve is closed, the temperatures of the solid media SD-M in the multiple small cold tanks converge, and the thermocline layer in the cryocline storage unit CPU is transformed into a temperature gradient between the multiple small cold tanks in the cryocline storage unit CPU.

[0076] Figures 3a and 3b further illustrate the influence of the choice of thermal conductivity on the formation of the thermocline layer and the cold energy exchange.

[0077] Figure 3a illustrates the prior art approach, using metal pipes as the material for the pipe PP. When releasing cold air, room-temperature, high-pressure air enters the metal pipe. Due to the metal's high thermal conductivity, the metal pipe rapidly heats up axially from the room-temperature end to the cryogenic end. However, since the solid medium has a lower thermal conductivity than the metal pipe, the axial heat transfer rate is slow, resulting in a large temperature difference DT between the metal pipe near the cryogenic end and the solid medium, leading to cold energy loss. From another perspective, because the metal's thermal conductivity is significantly higher than that of the solid medium, the heat transfer rate along the metal pipe exceeds the transfer rate of the axial temperature gradient within the solid medium, causing the hotter metal pipe to exchange heat with the downstream cryogenic solid medium in advance. The temperature difference between the two heat exchange media is large, resulting in a significant loss of cold energy.

[0078] Figure 3b illustrates an embodiment of the present invention, in which the axial thermal conductivity of the solid medium is equal to or greater than the axial thermal conductivity of the pipeline PP. During cooling, room-temperature, high-pressure air enters. Because the axial thermal conductivity Ka of the pipeline PP is close to or lower than the axial thermal conductivity Ka of the solid medium, the rate of heat conduction along the pipeline PP decreases, maintaining a low temperature difference DT between the solid medium and the pipeline PP, thereby reducing cooling energy loss. From another perspective, because the axial thermal conductivity Ka of the solid medium is not lower than the axial thermal conductivity Ka of the pipeline PP, the rate of heat conduction along the axial direction of the pipeline PP is close to or lower than the rate of heat conduction along the solid medium's axial thermocline layer, thus not affecting the propagation of the thermocline layer within the solid medium.

[0079] It should be noted that the descriptions of Figures 3a and 3b above are conceptual, intended to illustrate one embodiment of the present invention. In practical applications, the flow rate and pressure of normal-temperature, high-pressure air are directly related to the formation and propagation of the thermocline layer, and fall within the scope of prior art, so they will not be further elaborated here.

[0080] Referring to Figure 1, in one embodiment of the present invention, within the small cold tank, the radial thermal conductivity Kr of the pipeline PP and the thermal conductivity (including Kr and Ka) of the solid medium SD-M within the small cold tank are both higher than the axial thermal conductivity Ka of the pipeline PP. Given that the temperature of the solid medium SD-M within the small cold tank tends to converge during a static period, the present invention selects pipelines PP with lower axial thermal conductivity. This allows for rapid and sufficient radial exchange of cold energy between the pipeline PP and the solid medium SD-M within the small cold tank, facilitating the dispersion and preservation of the thermocline layer across the multiple small cold tanks.

[0081] 1 , in one embodiment of the present invention, the pipeline PP that does not directly contact the solid medium SD-M in the small cold tank is made of an insulating material.

[0082] Referring to Figure 2 , in one embodiment of the present invention, the main cold tank (MCD) utilizes a widely used cold storage tank structure using a solid medium stacked bed. However, the anisotropic thermal conductivity of the solid medium described in the present invention can still be achieved through the different spatial distributions of solid media with different thermal conductivities. Referring to Figure 2 , the solid medium (MCD-M) within the main cold tank is composed of two solid materials that are evenly distributed in the radial direction and alternately distributed in the axial direction. The black circles represent the solid medium (MCD-M1) within the main cold tank with the higher thermal conductivity, and the white circles represent the solid medium (MCD-M2) within the main cold tank with the lower thermal conductivity. The axial distribution of the solid medium (MCD-M2) with the lower thermal conductivity of the two solid media within the main cold tank can interrupt the continuous distribution of the solid medium (MCD-M1) with the higher thermal conductivity of the two solid media, thereby achieving an average axial thermal conductivity (Ka) of the solid medium lower than its average radial thermal conductivity (Kr).

[0083] In one embodiment of the present invention, a solid medium MCD-M1 with higher isotropic thermal conductivity and a solid medium MCD-M2 with lower isotropic thermal conductivity are selected inside the main cold tank MCD. Through multiple spatial distributions of the two solid media in the main cold tank MCD, the average axial thermal conductivity Ka of the solid medium MCD-M in the main cold tank is lower than its average radial thermal conductivity Kr. There are many ways to achieve the spatial distribution, which will not be repeated here.

[0084] Referring to Figure 1 , in one embodiment of the present invention, the solid medium having isotropic thermal conductivity is selected from a first group of media, which includes but is not limited to metals, carbon black, volcanic rock, basalt, conglomerate, sandstone, pebbles, and quartz. In another embodiment of the present invention, various artificial stones are selected as the solid medium to better control the effects of anisotropic thermal conductivity, which also falls within the scope of the present invention.

[0085] 1 and 2 , in one embodiment of the present invention, the solid medium is selected from a second medium group having anisotropic thermal conductivity, and the solid medium having anisotropic thermal conductivity is selected from the second medium group, which includes but is not limited to graphite, graphene, carbon fiber reinforced polymer materials, or metal fiber reinforced polymer composite materials.

[0086] A solid material with anisotropic thermal conductivity refers to a material with different thermal conductivity values ​​in different directions. This phenomenon may be caused by crystal structure, fiber arrangement, layered structure or other microstructural features. Common solid materials with anisotropic thermal conductivity include but are not limited to 1) layered materials: such as graphite, whose thermal conductivity in the plane is much higher than the thermal conductivity perpendicular to the plane; 2) fiber reinforced composite materials: if a material is composed of fibers with good thermal conductivity and a matrix with poor thermal conductivity, and the fibers are arranged along a specific direction, then the thermal conductivity of this material in the fiber direction will be higher than the thermal conductivity perpendicular to the fiber direction; the fibers can be one or more of carbon fibers, metal fibers, wood fibers, etc.

[0087] Referring to Figures 4a, 4b, and 4c, in one embodiment of the present invention, the material of the pipeline includes a carbon fiber layer composed of multiple layers of carbon fiber reinforced polymer material and a sandwich layer between the carbon fiber layers. The distribution density of the carbon fibers along one direction is increased in the carbon fiber layer to improve the thermal conductivity of the carbon fiber layer in that direction. Metal powder or graphite powder is added to the sandwich layer between the carbon fiber layers to improve the thermal conductivity of the interlayer of the pipeline passing through the pipe wall.

[0088] Figure 4a illustrates a schematic cross-sectional structure of the pipe PP described herein, including axial and radial wall sections. Figures 4b and 4c illustrate schematic radial and axial wall sections, respectively, showing four carbon fiber-reinforced polymer film layers (radial, axial, and radial carbon fiber layers, respectively) and three epoxy resin interlayers. The axial carbon fiber layers are more sparsely distributed than the radial carbon fiber layers, primarily contributing to the pipe PP's high-pressure resistance. The radial density of the carbon fibers is greater than the axial density, resulting in a higher radial thermal conductivity (Kr) around the pipe PP wall than the axial thermal conductivity (Ka) along the pipe PP wall. A powder of a material with a high thermal conductivity, such as metal powder or graphite powder, is evenly distributed within the epoxy resin interlayer. The addition of this high thermal conductivity powder to the epoxy resin interlayer simultaneously enhances the thermal conductivity (Ktt) of the interlayer within the pipe PP wall. In summary, by controlling the density and direction of carbon fibers, an anisotropic pipeline PP can be formed, where Kr>Ka. In order to further simultaneously improve the axial and radial thermal conductivities Ka and Kr in the pipeline PP, graphite, carbon black, metal powder, or other powders or polymer materials with thermal conductivity similar to that of metal powder can be added to the interlayer between the carbon fiber layers, thereby increasing the thermal conductivity Ktt of the pipeline PP interlayer. In one embodiment of the present invention, by selecting the Kr, Ka, and Ktt parameters of the pipeline, while considering parameters such as the pressure and temperature of the fluid storing and releasing cold, and while considering the specific heat rate or heat capacity rate of various solid media in the temperature range between room temperature and deep cold, the integrity and smoothness of the temperature oblique layer formed in the main cold tank during the cold storage and release process are improved, and the thickness of the temperature oblique layer is reduced.

[0089] Referring to Figure 5 , in one embodiment of the present invention, the pipeline comprises at least two materials with isotropic thermal conductivity. The material with the lower thermal conductivity of the two pipeline materials is used axially along the pipeline to block the continuous distribution of the material with the higher thermal conductivity of the two pipeline materials, while the material with the higher thermal conductivity of the two pipeline materials is continuously distributed radially along the pipeline. In one embodiment of the present invention, the pipeline (PP) is wound with multiple layers of polymer film. Cooling rings with higher thermal conductivity are distributed axially along the pipeline (PP), with materials with lower thermal conductivity used between the cooling rings. The higher thermal conductivity material and the lower thermal conductivity material are alternately connected to form the cooling pipe (PP), thereby forming an anisotropic pipeline (PP).

[0090] Referring to Figure 11 , in one embodiment of the present invention, the piping within the main or small cold tank comprises a parallel tube bundle consisting of multiple pipes parallel to the cold tank's axis. This parallel tube bundle still exhibits anisotropic thermal conductivity, with three thermal conductivities—interlayer thermal conductivity Ktt, axial and radial thermal conductivities Ka, and Kr—all varying.

[0091] In one embodiment of the present invention, the number of the main cooling tanks is one or more, wherein the main cooling tanks are connected in series or in parallel.

[0092] At the end of the cold storage stage, the temperature slope layer completely migrates from the main cold tank to the normal temperature end temperature slope layer storage unit APU; at the end of the cold storage stage and before the start of the cold release stage, the adiabatic valve is closed, and the temperature slope layer converts the temperature gradient between the first small cold tank SD1, the second small cold tank SD2, the third small cold tank SD3, the fourth small cold tank SD4, and the fifth small cold tank SD5; at the start of the cold release process, the temperature gradient is converted into the temperature slope layer in the main cold tank.

[0093] At the end of the cold release stage, the temperature slope layer is completely migrated from the main cold tank to the deep cold end temperature slope layer storage unit CPU; before the end of the cold release stage and the start of the cold storage stage, the adiabatic valve is closed, and the temperature slope layer is converted into the temperature gradient between the sixth small cold tank SD6, the seventh small cold tank SD7, the eighth small cold tank SD8, the ninth small cold tank SD9, and the tenth small cold tank SD10; at the start of the cold storage process, the temperature gradient is converted into the temperature slope layer in the main cold tank.

[0094] In one embodiment of the present invention, the multiple small cold tanks form a connected tank body, and the tank space within the connected tank body is isolated by the thermal insulation valve. In one embodiment of the present invention, high-pressure air is used as the fluid for storing and releasing cold, flowing within the pipeline space. The tank space can be at normal pressure, and using the thermal insulation valve to isolate and insulate the normal pressure space is engineering feasible.

[0095] In one embodiment of the present invention, the insulating valve isolates the tank space between the cold tanks while also isolating the pipeline space of the pipeline between the cold tanks, so as to prevent the pipeline itself from becoming an intermediary for cold energy exchange and interfering with the control of the cold energy exchange process.

[0096] Figure 6 further illustrates the state of the cold tank assembly near the end of the cold storage phase. Here, cryogenic high-pressure air enters the main cold tank from its cryogenic end (CTE), exchanging cold energy with the room-temperature solid medium MCD-M, forming a thermocline layer. Near the end of the cold storage phase, the thermocline layer shifts to the room-temperature end (ATE) near the main cold tank. At this point, the solid medium SD-M in the fifth, fourth, third, second, and first small cold tanks (SD5, SD4, SD3, SD2, and SD1) remains at room temperature.

[0097] Figure 7 illustrates the process of the thermocline layer migrating from the ambient temperature end of the main cold tank to the ambient temperature end thermocline layer storage unit (APU), i.e., the transition from state (a) of Figure 7 to state (b) of Figure 7. Figure 7 (a) illustrates the temperature distribution near the end of the cold storage shown in Figure 6; the fifth small cold tank SD5, fourth small cold tank SD4, third small cold tank SD3, second small cold tank SD2, and first small cold tank SD1 are at ambient temperature, the majority of the main cold tank is in deep cooling, and the main cold tank near the ambient temperature end is at ambient temperature. Furthermore, the temperature oblique layer begins to migrate toward the solid medium SD-M in the small cold tanks among the fifth small cold tank SD5, the fourth small cold tank SD4, the third small cold tank SD3, the second small cold tank SD2, and the first small cold tank SD1; the migration process ends when the normal temperature end of the main cold tank reaches deep cold; after the migration ends, the temperature oblique layer is distributed to the solid medium SD-M in the small cold tanks among the fifth small cold tank SD5, the fourth small cold tank SD4, the third small cold tank SD3, the second small cold tank SD2, and the first small cold tank SD1, the temperature of the solid medium in the fifth small cold tank SD5 is basically deep cold, and the temperature of the solid medium in the first small cold tank SD1 is basically normal temperature, reaching the state shown in Figure 7 (b).

[0098] Figure 8 is a schematic diagram of the cold tank device in a static state after completing the thermocline migration process shown in Figure 7. Figure 8 (a) shows the state at the end of migration and the beginning of static state; at this time, the adiabatic valve is closed, and thermal insulation is achieved between the small cold tanks. Furthermore, in the static state, the temperature of the solid medium SD-M in the small cold tanks converges, forming a temperature gradient between the multiple small cold tanks (including the first small cold tank SD1, the second small cold tank SD2, the third small cold tank SD3, the fourth small cold tank SD4, and the fifth small cold tank SD5), reaching the static state shown in Figure 8 (b).

[0099] Referring to Figures 7 and 8 , one advantage of this embodiment of the present invention is that it maintains the output temperature of the cold tank device at the ambient temperature end at ambient temperature, while also preserving the thermocline layer when the cold tank device is stationary, thus preventing significant convergence of the thermocline layer temperature. In one embodiment of the present invention, more than five small cold tanks constitute the ambient temperature end thermocline layer preservation unit (APU).

[0100] Furthermore, at the beginning of the cooling process, normal temperature high-pressure air enters the cold tank device from the normal temperature end of the normal temperature end inclined temperature layer storage unit APU, and the temperature gradient between the multiple small cold tanks (the first small cold tank SD1, the second small cold tank SD2, the third small cold tank SD3, the fourth small cold tank SD4, and the fifth small cold tank SD5) is reconverted into the inclined temperature layer as shown in Figure 8 (a) as shown in Figure 8 (b). As the cooling process progresses, the inclined temperature layer migrates into the main cold tank and resets to the state shown in Figure 7 (a).

[0101] Figure 9 further illustrates the state of the cold tank assembly near the end of the cooling phase. Here, room-temperature, high-pressure air enters the main cold tank from its room-temperature end ATE, exchanging cold energy with the deep-cold solid medium MCD-M within the main cold tank, forming a thermocline layer. Near the end of the cooling phase, the thermocline layer shifts to the deep-cold end CTE near the main cold tank. At this point, the solid media in the sixth, seventh, eighth, ninth, and tenth small cold tanks SD6, SD7, SD8, SD9, and SD10 are in a deep-cold state.

[0102] Figure 10 illustrates the process of the thermocline layer migrating from the cryogenic end of the main cooling tank to the cryogenic end thermocline layer storage unit CPU, i.e., the transition from the state in Figure 9 to the state in Figure 10(a). Figure 9 illustrates the temperature distribution near the end of the cooling release. Specifically, the sixth, seventh, eighth, ninth, and tenth small cooling tanks SD6, SD7, SD8, SD9, and SD10 are in cryogenic conditions, while the main cooling tank is mostly at room temperature, and the cryogenic end of the main cooling tank near the main cooling tank is also in cryogenic conditions. Furthermore, the inclined temperature layer begins to migrate toward the solid medium in the sixth small cold tank SD6, the seventh small cold tank SD7, the eighth small cold tank SD8, the ninth small cold tank SD9, and the tenth small cold tank SD10; the migration process ends when the deep cold end of the main cold tank reaches room temperature; after the migration ends, the inclined temperature layer is distributed to the solid medium SD-M in the sixth small cold tank SD6, the seventh small cold tank SD7, the eighth small cold tank SD8, the ninth small cold tank SD9, and the tenth small cold tank SD10, the temperature of the solid medium in the tenth small cold tank SD10 is basically deep cold, and the temperature of the solid medium in the sixth small cold tank SD6 is basically room temperature, reaching the state shown in Figure 10 (a).

[0103] Figure 10(b) is a schematic diagram of the cold tank device in a static state after completing the migration process of the thermocline layer shown in Figures 9 and 10(a). Figure 10(a) shows the state at the end of migration and the beginning of static state; at this time, the adiabatic valve is closed, and thermal insulation is achieved between the small cold tanks. Furthermore, in the static state, the temperature of the solid medium SD-M in the small cold tanks converges, forming a temperature gradient between the multiple small cold tanks (the sixth small cold tank SD6, the seventh small cold tank SD7, the eighth small cold tank SD8, the ninth small cold tank SD9, and the tenth small cold tank SD10), reaching the static state shown in Figure 10(b).

[0104] Referring to Figures 9 and 10 , one advantage of this embodiment of the present invention is that it maintains the output temperature of the cold tank device at the cryogenic end at a low temperature while preserving the thermocline layer when the device is stationary, thus preventing the temperature of the thermocline layer from drastically aligning. In one embodiment of the present invention, more than five small cold tanks constitute the cryogenic end thermocline layer preservation unit (CPU).

[0105] Furthermore, at the beginning of the cold storage process, deep-cold high-pressure air enters the cold tank device from the deep-cold end of the deep-cold end inclined temperature layer storage unit CPU, and the temperature gradient between the multiple small cold tanks (sixth small cold tank SD6, seventh small cold tank SD7, eighth small cold tank SD8, ninth small cold tank SD9, tenth small cold tank SD10) is re-converted into the inclined temperature layer as shown in Figure 10 (a) as shown in Figure 10 (b). As the cold release process progresses, the inclined temperature layer migrates into the main cold tank and resets to the state shown in Figure 9.

[0106] It should be noted that the concept of "thermal insulation" in this invention, including the "thermal insulation materials" and "thermal insulation valves," refers to materials or valves with the lowest possible thermal conductivity, as achieved by existing technologies. However, true "thermal insulation" is not possible. Furthermore, various existing methods, including but not limited to vacuum barriers, reflective mirrors, and physical separation, to block radiation, conduction, and convection of cold energy exchange, can also meet the requirements of the embodiments of this invention.

[0107] It should be noted that the "high-pressure air" described in the present invention is an embodiment of the present invention; other fluids for storing and releasing cold at different pressures can also be used as embodiments of the present invention.

[0108] In some embodiments, the temperature curves of the migrated thermocline layer and the reset thermocline layer in the embodiments of the present invention are not limited to be completely consistent with the original thermocline layer in the main cold tank.

[0109] "Normal temperature" and "deep cooling" in the embodiments of the present invention are only used to distinguish temperature differences; furthermore, it is understood that the temperature gradient layer between normal temperature and deep cooling does not limit the specific temperature / range of "normal temperature" and "deep cooling". As long as the temperature of "deep cooling" is lower than that of "normal temperature", those skilled in the art should not limit the scope of protection of the present invention accordingly.

[0110] The same applies to the "normal temperature end ATE" and "deep cold end CTE" of the main cold tank MCD of the present invention. The "deep cold end CTE" refers to the lower temperature side of the temperature slope layer formed in the main cold tank MCD after storing or releasing cold, while the corresponding "normal temperature end ATE" refers to the higher temperature side.

[0111] In the embodiment of the present invention, the number of small cold tanks is at least two to facilitate the formation of a temperature gradient (e.g., a temperature gradient) within a plurality of consecutive small cold tanks. The maximum number of small cold tanks is not limited and can be determined based on the design requirements of system cost and complexity. Conceptually, the more small cold tanks there are, the better the consistency of the temperature gradient layer in migrating and resetting the main cold tank.

[0112] It should be understood by those skilled in the art that the above embodiments are merely for the purpose of illustrating the present invention clearly, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and such changes or modifications are still within the scope of the present invention.

Claims

1. A cold tank device with anisotropic thermal conductivity, comprising: A cold tank and an axial pipeline running through the cold tank, wherein the cold tank comprises a main cold tank and a plurality of small cold tanks connected in series axially; characterized in that a solid medium is accumulated in the tank space between the inner wall of the cold tank and the outer wall of the pipeline, and high-pressure air at room temperature or deep cold enters the pipeline space inside the pipeline to exchange cold energy with the solid medium through the pipe wall of the pipeline; an insulating valve is arranged along the pipeline to isolate the tank space between the cold tanks; Wherein, the radial and axial directions of the main cold tank are used as the judgment criteria. Inside the main cold tank, the axial thermal conductivity of the solid medium in the main cold tank is lower than its radial thermal conductivity, the axial thermal conductivity of the pipeline is lower than its radial thermal conductivity, and the axial thermal conductivity of the solid medium is equal to or higher than the axial thermal conductivity of the pipeline; by such selection of thermal conductivity, during the cold storage or cold release process, the radial temperature of the solid medium is converged, and a temperature gradient layer distributed along the axial direction of the solid medium is realized; Among them, during the cold storage or release process, the inclined temperature layer migrates from the main cold tank to the multiple small cold tanks; after the cold storage or release process is completed, the adiabatic valve is closed, and the inclined temperature layer is converted into a temperature gradient between the multiple small cold tanks; when the cold storage or release process begins, the temperature gradient is converted into the inclined temperature layer in the main cold tank.

2. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: A plurality of the small cold tanks form a normal temperature end inclined temperature layer storage unit at the normal temperature end of the main cold tank; at the end of the cold storage stage, the inclined temperature layer completely enters the normal temperature end inclined temperature layer storage unit from the main cold tank.

3. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: A plurality of the small cold tanks form a deep cold end inclined temperature layer storage unit at the deep cold end of the main cold tank; at the end of the cold release stage, the inclined temperature layer completely enters the deep cold end inclined temperature layer storage unit from the main cold tank.

4. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: Inside the small cold tank, the radial thermal conductivity of the pipeline and the thermal conductivity of the solid medium in the small cold tank are both higher than the axial thermal conductivity of the pipeline.

5. The cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: The pipeline that does not directly contact the solid medium is made of insulating material.

6. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: Inside the main cold tank, two solid media with isotropic thermal conductivity are selected, wherein the axial distribution of the solid medium with lower thermal conductivity among the two solid media in the main cold tank can interrupt the continuous distribution of the solid medium with higher thermal conductivity among the two solid media, thereby achieving that the average axial thermal conductivity of the solid medium is lower than its average radial thermal conductivity.

7. A cold tank device with anisotropic thermal conductivity according to claim 6, characterized in that: The solid medium with isotropic thermal conductivity is selected from a first medium group, wherein the first medium group is selected from one or more of metal, carbon black, volcanic rock, basalt, conglomerate, sandstone, pebble or quartz stone.

8. The cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: The solid medium is selected from a solid medium with anisotropic thermal conductivity, and the solid medium with anisotropic thermal conductivity is selected from a second medium group, and the second medium group is selected from one or more of graphite, graphene, carbon fiber reinforced polymer material or metal fiber reinforced polymer composite material.

9. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: The material of the pipeline includes a carbon fiber layer composed of multiple layers of carbon fiber reinforced polymer material and a sandwich layer between the carbon fiber layers. The distribution density of the carbon fiber along one direction is increased in the carbon fiber layer to improve the thermal conductivity of the carbon fiber layer in this direction. Metal powder or graphite powder is added to the sandwich layer between the carbon fiber layers to improve the thermal conductivity of the interlayer of the pipeline passing through the pipe wall.

10. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: The material of the pipeline includes at least two materials with isotropic thermal conductivity, wherein the material with lower thermal conductivity of the two pipeline materials is used in the axial direction of the pipeline to block the continuous distribution of the material with higher thermal conductivity of the two pipeline materials, and the material with higher thermal conductivity of the two pipeline materials is used in a continuously distributed manner in the radial direction of the pipeline.

11. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: The pipeline inside the main cold tank or the small cold tank is a parallel pipe bundle composed of multiple pipelines parallel to the axial direction of the cold tank.

12. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: The number of the main cooling tanks is one or more, wherein the main cooling tanks are connected in axial series or in parallel.

13. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: The multiple small cold tanks are a connected tank body, and the tank body space in the connected tank body is separated by the insulation valve.

14. A cold tank device with anisotropic thermal conductivity according to claim 1, characterized in that: The thermal insulation valve isolates the tank space between the cold tanks and also isolates the pipeline space of the pipelines between the cold tanks.

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