A superconducting cable heat exchange device and method based on ultrasonic wave partition temperature regulation

Abstract

The application relates to a superconducting cable heat exchange device and method based on ultrasonic wave partition temperature regulation, which comprises a superconducting cable core, a vacuum Dewar tube, a cooling medium, an ultrasonic wave generating device, a distributed temperature sensing network, an ultrasonic wave transducing device and an intelligent temperature control module. The vacuum Dewar tube comprises an inner corrugated tube and an outer corrugated tube, the inner corrugated tube is located at the center of the outer corrugated tube, and the superconducting cable core is located at the center of the inner corrugated tube. The ultrasonic wave transducing device is arranged on the outer wall of the inner corrugated tube in the axial direction of the superconducting cable and is connected to each port of the ultrasonic wave generating device to receive an electric signal. The distributed temperature sensing network is arranged on the surface of the superconducting cable core to collect temperature distribution data of the superconducting cable in real time. The intelligent temperature control module receives the temperature distribution data and controls the parameter sequence of the ultrasonic wave generating device. Compared with the prior art, the application has the advantages of high device integration and economy.

Description

Technical Field

[0001] This invention relates to the field of thermal management technology for superconducting cables, and in particular to a heat exchange device and method for superconducting cables based on ultrasonic zoned temperature control, applicable to superconducting cable systems using cryogenic fluids such as liquid nitrogen and liquid helium as cooling media. Background Technology

[0002] With the development of superconducting power technology and the continuous increase in global electricity consumption, high-temperature superconducting cables have become a good solution for high-capacity, high-density power transmission due to their advantages such as low transmission loss, high current carrying capacity, and environmental friendliness. However, due to the special properties of superconducting materials, high-temperature superconducting cables must operate in ambient temperatures of 77 K and below. Therefore, dynamic thermal management of high-temperature superconducting cables is a key issue that needs to be addressed to ensure the safe and stable operation of the system. Currently, liquid nitrogen is widely used as a cooling medium in high-temperature superconducting cables. However, due to the thermal resistance effect of the fluid boundary layer, cryogenic systems of superconducting cables suffer from problems such as low heat transfer efficiency and high cooling medium consumption. Especially under high current, unbalanced load, or fault conditions, superconducting cables are prone to local overheating, threatening the maintenance of the superconducting state and insulation safety.

[0003] The cavitation effect of ultrasound, as a typical fluid-enhanced heat transfer method, has been studied in conventional heat dissipation fields. However, its application to the cooling system of superconducting cables still faces significant challenges: First, the multi-layered composite structure of superconducting cables leads to large energy transfer losses and low coupling efficiency of ultrasound; second, existing ultrasound-enhanced heat transfer schemes are only used to improve heat transfer efficiency and lack real-time interaction and dynamic response capabilities for local hot spots, faults, and other operating conditions in superconducting cable application scenarios, thus failing to achieve zoned, on-demand dynamic thermal management of superconducting cables.

[0004] The invention disclosed in CN112435799A provides a cooling structure for the current-carrying conductor of a three-coaxial superconducting cable and the current-carrying conductor of the superconducting cable. The structure includes: a cryogenic Dewar tube, which is a hollow cylindrical structure; and a current-carrying conductor disposed within the cryogenic Dewar tube, also a hollow cylindrical structure, which is wound with, from the inside out, a flexible skeleton, a first insulating layer, an A-phase superconducting layer, a second insulating layer, a B-phase superconducting layer, a third insulating layer, a C-phase superconducting layer, a shielding layer, a fifth insulating layer, and a protective layer. The hollow portion of the flexible skeleton forms a first liquid nitrogen channel; the gap between the inner wall of the cryogenic Dewar tube and the outer wall of the protective layer forms a second liquid nitrogen channel; the gap between the B-phase superconducting layer and the second insulating layer forms a third liquid nitrogen channel; and the gap between the B-phase superconducting layer and the third insulating layer forms a fourth liquid nitrogen channel. The first, second, third, and fourth liquid nitrogen channels are used for liquid nitrogen flow to cool the current-carrying conductor, shortening the heat conduction path of the B-phase superconducting layer and improving thermal stability. However, the above solutions do not effectively solve the problem of thermal resistance effect of fluid boundary layer, require a large amount of cooling medium, and fail to achieve zoned and on-demand dynamic thermal management of superconducting cables. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a heat exchange device and method for superconducting cables based on ultrasonic zoned temperature control. While maintaining the existing low-temperature cooling system structure, this invention constructs a superconducting cable thermal management system with real-time sensing and collaborative control capabilities through an array of ultrasonic transducers, ultrasonic generators, a distributed temperature sensing network, and an intelligent temperature control module. It proposes a dynamic thermal management scheme for superconducting cables with real-time response and zoned control capabilities, thereby achieving dynamic, precise, and efficient thermal management of superconducting cables.

[0006] The objective of this invention can be achieved through the following technical solutions: A superconducting cable heat exchanger based on ultrasonic zoned temperature control includes: Superconducting cable core, vacuum Dewar tube, cooling medium, ultrasonic generator, distributed temperature sensing network, ultrasonic transducer and intelligent temperature control module; The vacuum Dewar tube includes an inner corrugated tube and an outer corrugated tube, with the inner corrugated tube located at the center of the outer corrugated tube, and the superconducting cable core located at the center of the inner corrugated tube; a channel containing the cooling medium is formed between the superconducting cable core and the inner wall of the inner corrugated tube; the cooling medium is in contact with the wall surface of the superconducting cable core to form a fluid boundary layer; The ultrasonic generator is arranged on the outer wall of the inner corrugated tube; the ultrasonic transducers are arranged in an array along the axial direction of the superconducting cable on the outer wall of the inner corrugated tube and are respectively connected to each port of the ultrasonic generator to receive electrical signals; the distributed temperature sensing network is arranged on the surface of the superconducting cable core to collect the temperature distribution data of the superconducting cable in real time; the intelligent temperature control module receives the temperature distribution data and controls the parameter sequence of the ultrasonic generator.

[0007] Furthermore, the vacuum Dewar tube is a double-layer stainless steel corrugated tube, and the ultrasonic transducer is a piezoelectric ceramic element. The wall of the inner corrugated tube also serves as a medium for transmitting ultrasonic waves, allowing the ultrasonic waves generated by the ultrasonic transducer to enter the cooling medium between the inner corrugated tube and the superconducting cable core.

[0008] Furthermore, the ultrasonic generator is an electronic power device with adjustable frequency and power. Different frequencies and powers of electrical signals are set according to requirements and dynamically transmitted to the ultrasonic transducer, which ultimately generates ultrasonic waves of different frequencies and intensities.

[0009] Furthermore, the parameter sequence specifically includes the frequency and power of the AC signal generated by the ultrasonic generator; The ultrasonic generator generates AC signals of different frequencies and powers according to the parameter sequence and transmits them to the ultrasonic transducer; the distributed temperature sensing network consists of multiple fiber optic temperature sensors arranged at certain angles on the surface of the superconducting cable core.

[0010] The present invention also provides a heat exchange method for a superconducting cable heat exchange device based on ultrasonic zoned temperature control as described above, comprising: Acquire temperature distribution data of the superconducting cable; based on the temperature distribution data, with the goal of minimizing the maximum temperature, temperature gradient and total ultrasonic power of the superconducting cable, solve for the optimal control parameters of the electrical signals transmitted from the ultrasonic generator to each zone and dynamically transmit them to the ultrasonic transducer. Ultrasonic waves of different frequencies and intensities are generated by the ultrasonic transducer and transmitted into the cooling medium to form an ultrasonic sound field.

[0011] Furthermore, the objective function aimed at minimizing the maximum temperature, temperature gradient, and total ultrasonic power of the superconducting cable is expressed as: The decision variables corresponding to the optimal control parameters are expressed as follows: Among them, P i f i Let T be the power and frequency of the electrical signal transmitted to the i-th partition, respectively. i Let w1, w2, and w3 be the temperature of the superconducting cable within the i-th partition, and w1, w2, and w3 be weighting coefficients. Let T be the average temperature across all zones, T be the state variable, and U be the decision variable.

[0012] Furthermore, the process of generating ultrasonic waves by the ultrasonic transducer specifically includes: when the cooling medium is liquid nitrogen or liquid helium, the ultrasonic transducer converts the electrical signal into mechanical vibration through the piezoelectric effect, and the mechanical vibration is then transmitted into the liquid nitrogen or liquid helium through the wall of the inner corrugated tube to form an ultrasonic sound field.

[0013] Furthermore, the process of converting electrical signals into mechanical vibrations specifically includes: Upon receiving the electrical signal, the piezoelectric ceramic sheet in the ultrasonic transducer undergoes periodic expansion and contraction due to the piezoelectric effect, thereby generating mechanical vibrations at the same frequency as the electrical signal. The mechanical vibrations propagate to the wall of the inner bellows in the form of ultrasonic waves, eventually entering the liquid nitrogen or liquid helium and forming an ultrasonic sound field.

[0014] Furthermore, the ultrasonic sound field will cause the formation of a cavity when it propagates in the liquid nitrogen or liquid helium; the cavity expands and collapses, forming a local high temperature and high pressure zone and destroying the fluid boundary layer formed by the contact between the cooling medium and the wall of the superconducting cable core.

[0015] Furthermore, the methods also include: Based on the finite element method, the thermal characteristics of superconducting cables are analyzed to obtain regional risk distribution information. Based on the regional risk distribution information, the layout density of ultrasonic transducers in high-risk areas is increased.

[0016] Compared with the prior art, the present invention has the following advantages: (1) The present invention obtains temperature distribution data of superconducting cable by means of distributed temperature sensing network, and further sets electrical signals of different frequencies and powers according to temperature distribution data by ultrasonic generator and dynamically transmits them to ultrasonic transducer. Ultrasonic waves of different frequencies and intensities are generated by ultrasonic transducer, which are transmitted into cooling medium and form ultrasonic sound field. Combined with ultrasonic cavitation effect, the fluid boundary layer is destroyed, thus achieving the purpose of enhancing the convective heat transfer effect between the surface of superconducting cable and cooling medium.

[0017] Furthermore, by adjusting the frequency and power of the electrical signals connected to each ultrasonic transducer by the ultrasonic generator, the ultrasonic transducers can work alternately or simultaneously. At the same time, by monitoring the temperature of different areas on the superconducting cable in real time, the distribution density of the ultrasonic generator can be adjusted, thereby generating ultrasonic sound fields of different intensities in different areas, thus achieving regional enhanced heat transfer and temperature control for the superconducting cable.

[0018] The above scheme, while maintaining the existing cryogenic cooling system structure, introduces a controllable ultrasonic vibration field to generate micro-cavities, release heat energy, and disrupt the fluid boundary layer, thereby achieving the disruption of the cooling medium boundary layer and a significant improvement in the heat exchange performance of the superconducting cable system.

[0019] (2) This invention integrates a superconducting cable core, a double-layer Dewar tube, a distributed temperature sensing network, an ultrasonic generator and an ultrasonic transducer into a superconducting cable enhanced heat exchange device, thereby achieving dynamic control of the heat exchange performance of the superconducting cable; and the cooling medium in the device can be selected from a variety of liquids or gases, with a small amount required, which has good economic efficiency and strong industrial applicability.

[0020] (3) By setting ultrasonic generators and ultrasonic transducers at different positions on the surface of the inner Dewar tube, the present invention regulates the frequency and power of the electrical signals connected to the ultrasonic transducers in different areas, changes the intensity of the ultrasonic sound field in a certain area, and thus realizes dynamic management of the heat exchange effect between the superconducting cable core and the cooling medium in different areas. Attached Figure Description

[0021] Figure 1 This is a structural diagram of a superconducting cable heat exchange device based on ultrasonic zoned temperature control provided in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0028] Definitions: Finite Element Simulation Method: The finite element simulation method is a numerical analysis technique that discretizes a complex continuous physical system (such as a superconducting cable and its surrounding medium) into a finite number of interconnected simple subdomains (i.e., elements). Within each element, approximate functions are used to represent field variables (such as temperature and stress). Finally, a system of algebraic equations for the overall system is constructed and solved to simulate and analyze its thermal, electrical, and mechanical physical field behavior under actual operating conditions. In the thermal characteristic analysis of this superconducting cable, this method is used to calculate the temperature distribution, heat diffusion, and potential hotspots during cable operation, thereby identifying areas with high overheating risk. Based on the obtained regional risk distribution information, the density of ultrasonic transducers can be increased in high-risk areas to enhance the real-time monitoring and early warning capabilities for localized overheating or quenching failure of the cable.

[0029] Thermal resistance is a physical property that measures a material's or structure's ability to impede heat conduction; its quantitative parameter is called thermal resistance. It is analogous to resistance in a circuit, with temperature difference likened to voltage and heat flow to current. The greater the thermal resistance, the greater the temperature difference generated for the same amount of heat. This effect is prevalent in all heat transfer paths and is a core basis for heat dissipation and insulation design, crucial for electronic chip heat dissipation, building insulation, and cryogenic maintenance of superconducting cables.

[0030] Ultrasonic cavitation effect: This refers to the process by which, when high-intensity ultrasound propagates in a liquid, the liquid molecules, under the influence of periodically changing sound pressure, generate numerous tiny bubbles (cavitation nuclei) inside and on their surface. These bubbles rapidly expand during the negative pressure phase of the sound wave and then collapse abruptly during the positive pressure phase. At the moment of collapse (lasting only a few microseconds), extreme high temperatures (approximately 5000 K), high pressures (approximately 1000 atmospheres), intense shock waves, and high-speed microjets are generated within a very small space. This effect can effectively pulverize and emulsify substances and promote chemical reactions, but it can also cause cavitation damage to solid surfaces.

[0031] The piezoelectric effect refers to a reversible physical effect exhibited by certain crystalline or ceramic materials (called piezoelectric materials): when mechanical stress is applied, an electric charge is generated on their surface (positive piezoelectric effect); conversely, when an external electric field is applied, they undergo a slight deformation (inverse piezoelectric effect). This direct bidirectional conversion between mechanical and electrical energy makes piezoelectric materials the core working principle of electronic components such as sensors, actuators, and ultrasonic transducers.

[0032] Example 1 like Figure 1 As shown, the present invention provides a superconducting cable heat exchange device based on ultrasonic zoned temperature control, comprising: While maintaining the existing cryogenic cooling system structure, this paper proposes a dynamic thermal management scheme for superconducting cables with real-time response and zoned control capabilities. This scheme utilizes arrayed ultrasonic transducers, ultrasonic generators, and a distributed temperature sensing network. This achieves dynamic, precise, and efficient thermal management of the superconducting cables. Figure 1 As shown, the entire system mainly consists of a superconducting cable core, a vacuum Dewar tube, an ultrasonic generator, a distributed temperature sensing network, ultrasonic transducers (arranged in an array along the axial direction), and an intelligent temperature control module. This constructs a superconducting cable thermal management system with real-time sensing and collaborative control capabilities. Each component works collaboratively to enhance heat transfer in the superconducting cable. Specific descriptions of each component are as follows: Superconducting cable core: The superconducting cable core is the core current-carrying structure of a superconducting cable, mainly composed of a skeleton, conductor layer, semiconducting layer, insulation layer, and shielding layer. Among these, the conductor layer, wound with superconducting tape, is one of the main sources of heat in the superconducting cable system. Simultaneously, the superconducting tape must operate in a low-temperature environment. Therefore, the heat transfer enhancement scheme proposed in this invention focuses on the thermal stability of the superconducting cable core.

[0033] Vacuum Dewar: This consists of an inner corrugated tube and an outer corrugated tube. The inner corrugated tube serves as a flow channel for liquid nitrogen. In the heat exchange enhancement scheme of this invention, the wall surface of the inner corrugated tube also acts as a conductive medium for ultrasonic waves, transmitting the ultrasonic waves generated by the ultrasonic transducer into the liquid nitrogen between the inner corrugated tube and the superconducting cable core. The outer corrugated tube serves as a high-vacuum insulation layer to isolate heat from the external environment. In this invention, the inner and outer Dewar tubes form a double-layer Dewar, with a basic structure of double-layer stainless steel corrugated tubes.

[0034] Ultrasonic generator: The ultrasonic generator is the energy source of ultrasonic waves in the enhanced heat exchange scheme of this invention. It is essentially an electronic power device with adjustable frequency and power. Different frequencies and powers of electrical signals can be set according to requirements and dynamically transmitted to the ultrasonic transducer. Finally, ultrasonic waves of different frequencies and intensities are generated by the ultrasonic transducer.

[0035] Ultrasonic transducer: As a core component of the dynamic thermal management scheme of this invention, the ultrasonic transducer is essentially a piezoelectric ceramic element. It converts the high-frequency electrical signal generated by the ultrasonic generator into mechanical vibration through the piezoelectric effect, which is then transmitted to the cooling medium liquid nitrogen via the inner corrugated tube, forming an ultrasonic sound field. In this invention, the ultrasonic transducers are arranged in an array along the axial direction of the superconducting cable on the outer wall of the inner corrugated tube in the vacuum Dewar tube. By receiving electrical signals of different frequencies and powers from the ultrasonic generator, it generates ultrasonic sound fields of varying intensities, enabling regional enhanced heat transfer and temperature control. Furthermore, thermal characteristic analysis of the superconducting cable can be conducted based on finite element simulation to identify high-risk areas prone to localized overheating, and the density of the ultrasonic transducers in these areas can be increased, thereby enhancing the temperature control capability of the superconducting cable in those areas.

[0036] Distributed temperature sensing network: The distributed temperature sensing network consists of four fiber optic temperature sensors arranged circumferentially at 90° intervals on the surface of the superconducting cable core. Its function is to collect the temperature distribution data of the superconducting cable in real time and provide timely feedback.

[0037] Intelligent Temperature Control Module: The innovation of this invention is particularly evident in its intelligent temperature control strategy. The intelligent temperature control module incorporates a temperature-sound field response model calibrated through experiments or simulations, capable of quantifying the dynamic impact of different ultrasonic parameters on local heat transfer and temperature changes. Based on the current temperature distribution of the superconducting cable, the intelligent temperature control module solves a multi-objective optimization problem in real time, dynamically generating the optimal operating frequency and power of the ultrasonic transducers in each region, thus achieving active temperature regulation of the superconducting cable system.

[0038] Specifically, the intelligent temperature control module, based on the current temperature distribution of all zones in the superconducting cable, aims to achieve multiple objectives: overall temperature uniformity (temperature gradient), rapid suppression of local overheating (temperature), and minimization of total system energy consumption (total ultrasonic power). It then solves for the optimal control parameter sequence for the ultrasonic transducers in each zone in real time. Finally, this optimal parameter control sequence is output to the ultrasonic generator in real time, thereby driving the ultrasonic transducers in each zone to operate. Simultaneously, the intelligent temperature control module continuously solves for new control parameter sequences at a fixed control cycle, thus achieving dynamic temperature regulation of the superconducting cable.

[0039] Preferred, The specific steps for solving multi-objective optimization problems are as follows: 1. Obtain temperature data for each zone of the superconducting cable.

[0040] 2. Based on the current temperature distribution, with the target temperature of each zone of the superconducting cable as the independent variable, the working parameters of the ultrasonic wave can be obtained according to the "temperature-sound field" response model. Furthermore, the optimization problem is constructed with the following multiple objectives: minimizing the maximum temperature of the superconducting cable, minimizing the temperature gradient, and minimizing the total ultrasonic power (corresponding to the core objectives of "rapidly suppressing overheating", "maintaining overall temperature uniformity", and "reducing system energy consumption").

[0041] 3. The solver built into the intelligent temperature control module quickly calculates a set of ultrasonic control parameters that optimizes the above-mentioned comprehensive objectives (i.e., the power, frequency, and other parameters that should be input to each ultrasonic transducer at this moment).

[0042] 4. The above control parameter sequence is sent to the ultrasonic generator in real time to drive each ultrasonic transducer to perform.

[0043] 5. Wait for the next control cycle, and repeat the above process based on the latest temperature data to achieve dynamic and real-time thermal management.

[0044] Superconducting cables use liquid nitrogen as a cooling medium, which flows between the cable core and the inner corrugated tube. At this point, due to the viscosity of the liquid nitrogen, the flow of liquid nitrogen near the fluid boundary layer (i.e., near the wall) is slow, resulting in a large thermal resistance, which restricts the convective heat transfer between the cable core and the liquid nitrogen.

[0045] To enhance convective heat transfer between the superconducting cable and liquid nitrogen, several ultrasonic transducers are arranged in an array along the axial direction of the superconducting cable on the outer wall of the inner corrugated tube within a vacuum Dewar duct, and each is connected to the electrical signal output port of an ultrasonic generator. The ultrasonic generator can then produce high-frequency alternating current signals of different frequencies and powers as needed, which are transmitted to each of the arrayed ultrasonic transducers. Furthermore, each ultrasonic transducer converts the high-frequency alternating current signals into high-frequency mechanical vibrations through the piezoelectric effect. Finally, these high-frequency vibrations are transmitted through the wall of the inner corrugated tube to the cooling medium, liquid nitrogen, creating ultrasonic sound fields of varying intensities within the regions of each ultrasonic transducer.

[0046] In the above scheme, by adjusting the frequency and power of the electrical signals connected to each ultrasonic transducer from the ultrasonic generator, the ultrasonic transducers can operate alternately or simultaneously, thereby generating ultrasonic sound fields of varying intensities in different regions where each transducer is located. Due to the high frequency and high energy of the ultrasonic sound field, its propagation in the liquid nitrogen cooling medium leads to the generation of numerous tiny cavities. These cavities rapidly expand and violently collapse within microseconds, forming localized high-pressure zones on an extremely short timescale. This disturbance effectively disrupts the originally slow-flowing fluid boundary layer, thereby altering the fluid properties, reducing the thermal resistance of the boundary layer, and enhancing the convective heat transfer effect between the superconducting cable and the liquid nitrogen cooling medium. Furthermore, the enhancing effect of ultrasound on heat transfer can be adjusted in real time by changing the intensity of the ultrasonic sound field, thus achieving targeted, regionally enhanced heat transfer and temperature control for the superconducting cable.

[0047] Besides enhancing the heat exchange between the superconducting cable and the cooling medium, the most important aspect of this invention is achieving real-time temperature control of different regions within the superconducting cable, thereby improving the dynamic thermal stability of the superconducting cable system. The intelligent temperature control module acquires temperature data collected by a distributed temperature sensing network at a fixed control cycle. When a temperature change is detected in a certain region, based on a "temperature-sound field" response model, and with multiple objectives including overall temperature uniformity (temperature gradient), rapid suppression of local overheating (temperature), and minimizing total system energy consumption (total ultrasonic power), a set of ultrasonic control parameters is calculated that not only effectively suppresses current hot spots but also maximizes the maintenance of overall temperature field equilibrium. For example, while enhancing cooling of overheated areas, the ultrasonic intensity in upstream and downstream regions can be appropriately reduced, weakening convective heat transfer in these regions and allowing more cooling energy to be used for cooling overheated areas, thus achieving stable and efficient thermal management.

[0048] In summary, the superconducting cable dynamic thermal management scheme based on ultrasonic enhanced heat transfer and zoned temperature control not only enhances the convective heat transfer between the superconducting cable and the cooling medium, thereby reducing the cooling medium consumption of the superconducting cable cryogenic system and further improving the economy of the superconducting cable; it also enables regional dynamic temperature management based on an array of ultrasonic transducers and a distributed temperature sensing network, improving the dynamic thermal stability of the superconducting cable under abnormal operating conditions such as local heating and local hot spots.

[0049] It is important to note that the aforementioned heat transfer enhancement scheme for superconducting cables based on ultrasonic cavitation effects is also applicable to superconducting cables using liquid helium, cryogenic helium, or other gases as cooling media. Specifically, for superconducting cables using liquid helium as the cooling medium, the principle of ultrasonic-enhanced heat transfer is still based on the cavitation effect of ultrasound. However, for superconducting cables using cryogenic helium or other gases as the cooling medium, the principle of ultrasonic-enhanced heat transfer is no longer primarily based on cavitation. Instead, ultrasound enhances the microscale vortices in the cooling gas, increasing the flow complexity of the cooling gas and thus improving the local heat transfer efficiency.

[0050] Example 2 This embodiment provides a heat exchange method for a superconducting cable enhanced heat exchange device based on ultrasonic cavitation effect, as described in Embodiment 1, including the following steps: S1: Obtain the temperature distribution data of the superconducting cable; based on the temperature distribution data, with the goal of minimizing the maximum temperature, temperature gradient and total ultrasonic power of the superconducting cable, solve for the optimal control parameters of the electrical signals transmitted from the ultrasonic generator to each zone and dynamically transmit them to the ultrasonic transducer. Specifically, The objective function for minimizing the maximum temperature, temperature gradient, and total ultrasonic power of the superconducting cable is expressed as: The decision variables corresponding to the optimal control parameters are expressed as follows: Among them, P i f i Let T be the power and frequency of the electrical signal transmitted to the i-th partition, respectively. i Let w1, w2, and w3 be the temperature of the superconducting cable within the i-th partition, and w1, w2, and w3 be weighting coefficients. Let T be the average temperature across all zones, T be the state variable, and U be the decision variable.

[0051] Specifically, the superconducting cable uses liquid nitrogen as the cooling medium, which flows between the cable core and the inner corrugated tube. At this point, due to the viscosity of the liquid nitrogen, the flow of liquid nitrogen near the fluid boundary layer (i.e., near the wall) is slow, resulting in a large thermal resistance, which restricts the convective heat transfer between the cable core and the liquid nitrogen.

[0052] Preferably, to enhance convective heat transfer between the superconducting cable and liquid nitrogen, an array of ultrasonic transducers is arranged on the outer wall of the inner corrugated tube within the double-layer Dewar tube of the superconducting cable, and connected to each port of the ultrasonic generator, such as... Figure 1 As shown in the diagram, the ultrasonic generator produces high-frequency alternating current signals of different frequencies and powers, which are then transmitted to the ultrasonic transducer. The ultrasonic transducer converts the high-frequency alternating current signals into high-frequency mechanical vibrations through the piezoelectric effect. Finally, the high-frequency vibrations generated by the ultrasonic transducer are transmitted into the liquid nitrogen through the inner corrugated pipe wall, forming an ultrasonic sound field.

[0053] Preferably, by adjusting the frequency and power of the electrical signals connected to different ultrasonic transducers by the ultrasonic generator, the ultrasonic transducers can operate alternately or simultaneously, thereby generating ultrasonic sound fields of different intensities in different regions of the superconducting cable. Furthermore, due to the high frequency and energy of the ultrasonic sound field, its propagation in liquid nitrogen will result in the generation of numerous tiny cavities. These cavities rapidly expand and violently collapse within microseconds, forming localized high-temperature and high-pressure zones on an extremely short timescale. This disturbance effectively disrupts the originally slow-flowing fluid boundary layer, thereby altering the properties of the fluid at that location, reducing the thermal resistance of the boundary layer, and significantly enhancing convective heat transfer between the superconducting cable and the liquid nitrogen.

[0054] Preferably, by adjusting the frequency and power of the electrical signal received by the ultrasonic transducer in each region of the superconducting cable, the intensity of the ultrasonic sound field in a certain region can be changed, thereby dynamically managing the heat exchange effect between the superconducting cable and liquid nitrogen in that region. When local hot spots appear in the superconducting cable, causing a local temperature increase, the above-mentioned regional heat exchange effect control method can specifically enhance the convective heat exchange between the superconducting cable and liquid nitrogen in the region where the local hot spot is located, which can improve the dynamic thermal stability of the superconducting cable to a certain extent.

[0055] S2: Ultrasonic waves of different frequencies and intensities are generated by an ultrasonic transducer, which are transmitted into the cooling medium and form an ultrasonic sound field.

[0056] Preferably, the cooling medium is liquid nitrogen, liquid helium, or cryogenic helium.

[0057] Preferably, the process of generating ultrasonic waves by the ultrasonic transducer specifically includes: when the cooling medium is liquid nitrogen or liquid helium, the ultrasonic transducer converts the electrical signal into mechanical vibration through the piezoelectric effect, and the mechanical vibration is then transmitted into the liquid nitrogen or liquid helium through the wall of the inner corrugated tube to form an ultrasonic sound field.

[0058] Specifically, the process of converting electrical signals into mechanical vibrations includes: Upon receiving an electrical signal, the piezoelectric ceramic sheet in the ultrasonic transducer undergoes periodic expansion and contraction due to the piezoelectric effect, thereby generating mechanical vibrations that are consistent with the frequency of the electrical signal. The mechanical vibrations propagate to the wall of the inner bellows in the form of ultrasonic waves, eventually entering liquid nitrogen or liquid helium and forming an ultrasonic sound field.

[0059] Preferably, the propagation of the ultrasonic field in liquid nitrogen or liquid helium will cause the formation of a cavity; the cavity expands and collapses, forming a local high temperature and high pressure zone and destroying the fluid boundary layer formed by the contact between the cooling medium and the wall of the superconducting cable core.

[0060] Preferably, by adjusting the frequency and power of the electrical signals connected to the ultrasonic transducers in different areas, the intensity of the ultrasonic sound field in a certain area is changed, thereby dynamically managing the heat exchange effect between the superconducting cable core and the cooling medium in the area.

[0061] Preferably, the thermal characteristics of the superconducting cable are analyzed based on the finite element simulation method to obtain regional risk distribution information, and the layout density of ultrasonic transducers in high-risk areas is increased based on the regional risk distribution information.

[0062] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A superconducting cable heat exchanger based on ultrasonic zoned temperature control, characterized in that, include: Superconducting cable core, vacuum Dewar tube, cooling medium, ultrasonic generator, distributed temperature sensing network, ultrasonic transducer and intelligent temperature control module; The vacuum Dewar tube includes an inner corrugated tube and an outer corrugated tube, with the inner corrugated tube located at the center of the outer corrugated tube, and the superconducting cable core located at the center of the inner corrugated tube; a channel containing the cooling medium is formed between the superconducting cable core and the inner wall of the inner corrugated tube; the cooling medium is in contact with the wall surface of the superconducting cable core to form a fluid boundary layer; The ultrasonic generator is arranged on the outer wall of the inner corrugated tube; the ultrasonic transducers are arranged in an array along the axial direction of the superconducting cable on the outer wall of the inner corrugated tube and are respectively connected to each port of the ultrasonic generator to receive electrical signals; the distributed temperature sensing network is arranged on the surface of the superconducting cable core to collect the temperature distribution data of the superconducting cable in real time; the intelligent temperature control module receives the temperature distribution data and controls the parameter sequence of the ultrasonic generator.

2. The superconducting cable heat exchanger based on ultrasonic zoned temperature control according to claim 1, characterized in that, The vacuum Dewar tube is a double-layer stainless steel corrugated tube, and the ultrasonic transducer is a piezoelectric ceramic element. The wall of the inner corrugated tube also serves as a medium for transmitting ultrasonic waves, allowing the ultrasonic waves generated by the ultrasonic transducer to enter the cooling medium between the inner corrugated tube and the superconducting cable core.

3. The superconducting cable heat exchanger based on ultrasonic zoned temperature control according to claim 1, characterized in that, The ultrasonic generator is an electronic power device with adjustable frequency and power. Different frequencies and powers of electrical signals are set according to requirements and dynamically transmitted to the ultrasonic transducer, which ultimately generates ultrasonic waves of different frequencies and intensities.

4. The superconducting cable heat exchanger based on ultrasonic zoned temperature control according to claim 1, characterized in that, The parameter sequence specifically includes the frequency and power of the alternating current signal generated by the ultrasonic generator; The ultrasonic generator generates AC signals of different frequencies and powers according to the parameter sequence and transmits them to the ultrasonic transducer; the distributed temperature sensing network consists of multiple fiber optic temperature sensors arranged at certain angles on the surface of the superconducting cable core.

5. A heat exchange method for a superconducting cable heat exchange device based on ultrasonic zoned temperature control as described in any one of claims 1-4, characterized in that, include: Acquire temperature distribution data of the superconducting cable; based on the temperature distribution data, with the goal of minimizing the maximum temperature, temperature gradient and total ultrasonic power of the superconducting cable, solve for the optimal control parameters of the electrical signals transmitted from the ultrasonic generator to each zone and dynamically transmit them to the ultrasonic transducer. Ultrasonic waves of different frequencies and intensities are generated by the ultrasonic transducer and transmitted into the cooling medium to form an ultrasonic sound field.

6. The method for heat exchange of superconducting cables based on ultrasonic zoned temperature control according to claim 5, characterized in that, The objective function for minimizing the maximum temperature, temperature gradient, and total ultrasonic power of the superconducting cable is expressed as: The decision variables corresponding to the optimal control parameters are expressed as follows: Among them, P i f i Let T be the power and frequency of the electrical signal transmitted to the i-th partition, respectively. i Let w1, w2, and w3 be the temperature of the superconducting cable within the i-th partition, and w1, w2, and w3 be weighting coefficients. Let T be the average temperature across all zones, T be the state variable, and U be the decision variable.

7. A method for heat exchange of superconducting cables based on ultrasonic zoned temperature control according to claim 5, characterized in that, The process of generating ultrasonic waves by the ultrasonic transducer specifically includes: when the cooling medium is liquid nitrogen or liquid helium, the ultrasonic transducer converts the electrical signal into mechanical vibration through the piezoelectric effect, and the mechanical vibration is then transmitted into the liquid nitrogen or liquid helium through the wall of the inner corrugated tube to form an ultrasonic sound field.

8. A method for heat exchange of superconducting cables based on ultrasonic zoned temperature control according to claim 7, characterized in that, The process of converting the electrical signal into mechanical vibration specifically includes: Upon receiving the electrical signal, the piezoelectric ceramic sheet in the ultrasonic transducer undergoes periodic expansion and contraction due to the piezoelectric effect, thereby generating mechanical vibrations at the same frequency as the electrical signal. The mechanical vibrations propagate to the wall of the inner bellows in the form of ultrasonic waves, eventually entering the liquid nitrogen or liquid helium and forming an ultrasonic sound field.

9. A method for heat exchange of superconducting cables based on ultrasonic zoned temperature control according to claim 8, characterized in that, When the ultrasonic field propagates in the liquid nitrogen or liquid helium, it will cause the formation of a cavity; the cavity expands and collapses, forming a local high temperature and high pressure zone and destroying the fluid boundary layer formed by the contact between the cooling medium and the wall of the superconducting cable core.

10. A method for heat exchange of superconducting cables based on ultrasonic zoned temperature control according to claim 5, characterized in that, The method further includes: Based on the finite element method, the thermal characteristics of superconducting cables are analyzed to obtain regional risk distribution information. Based on the regional risk distribution information, the layout density of ultrasonic transducers in high-risk areas is increased.

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