Temperature monitoring optical cable and cable assembly

Abstract

The embodiment of the invention provides a temperature monitoring optical cable and a cable assembly, and belongs to the field of optical cables. The temperature monitoring optical cable comprises a heating cable body, a heat transfer layer, at least one pressure sensing unit, a heat preservation buffer layer and a temperature sensing layer. The heat transfer layer covers the heating cable body so as to transfer heat of the heating cable body; the pressure sensing unit is arranged on the outer side of the heat transfer layer and extends in the length direction of the heating cable body; the temperature sensing layer wraps the pressure sensing unit, the temperature sensing layer is configured to apply pressure to one side of the pressure sensing unit according to temperature change, the pressure sensing unit generates a strain signal when being subjected to pressure so as to feed back the temperature of the temperature sensing layer, and the heat preservation buffer layer is used for preventing heat of the heating cable body from being transmitted to the temperature sensing layer. According to the temperature monitoring optical cable provided by the embodiment of the invention, the temperature of the environment where the superconducting cable of the cable assembly is located can be continuously monitored, and the working temperature monitoring precision of the superconducting cable is improved.

Description

Technical Field

[0001] The present application relates to the field of optical cable technology, and in particular to a temperature monitoring optical cable and a cable assembly. Background Art

[0002] Compared with traditional power cables, superconducting cables have the advantages of low loss, large transmission capacity, and small cable size, and have good development prospects in specific large-capacity power transmission applications.

[0003] In related technologies, superconducting cables are generally placed in an environment of low-temperature cooling medium. The temperature monitoring method of superconducting cables is usually to install sensors at key locations, such as temperature sensors, pressure sensors, etc., to determine whether there is a heat leakage problem by monitoring temperature changes and pressure fluctuations of the circulating cooling medium.

[0004] However, it is difficult for the sensor components to fully reflect the entire system, especially the temperature distribution along the entire length of the superconducting cable. In addition, the temperature sensor has a slow response speed and can only alarm when heat leakage causes a significant increase in temperature or a significant decrease in pressure, resulting in poor monitoring accuracy. Summary of the invention

[0005] The present application provides a temperature monitoring optical cable and a cable assembly, which are used to solve the technical problems in the related art that the temperature monitoring accuracy of the detection sensor arranged on the superconducting cable is poor and it is difficult to locate the position of the heat leakage source.

[0006] On the one hand, the present application provides a temperature monitoring optical cable, comprising:

[0007] Heating cable body;

[0008] A heat transfer layer, covering the heating cable body to transfer heat from the heating cable body;

[0009] At least one pressure sensing unit is arranged outside the heat transfer layer, and the pressure sensing unit extends along the length direction of the heating cable body;

[0010] a temperature sensing layer covering the pressure sensing unit, wherein the temperature sensing layer is configured to apply pressure to one side of the pressure sensing unit in response to temperature changes, and the pressure sensing unit generates a strain signal when receiving the pressure to provide feedback on the temperature of the temperature sensing layer;

[0011] The heat-insulating buffer layer is arranged between the temperature sensing layer and the pressure sensing unit to prevent the heat of the heating cable body from being transmitted to the temperature sensing layer.

[0012] In a possible implementation, in the temperature monitoring optical cable of the embodiment of the present application, the thermal insulation buffer layer is arranged to protrude toward the temperature sensing layer at a position corresponding to the pressure sensing unit, the protruding portion of the thermal insulation buffer layer is connected to the temperature sensing layer, and the thermal insulation buffer layer and the temperature sensing layer are separated by the protruding portion to form a cavity.

[0013] In a possible implementation, in the temperature monitoring optical cable of the embodiment of the present application, a side of the thermal insulation buffer layer facing away from the pressure sensing unit is coated with a thermal insulation layer, or a protruding portion of the thermal insulation buffer layer is provided with a thermal insulation layer.

[0014] In a possible implementation, the heat insulation layer abuts against the temperature sensing layer, and the thermal conductivity of the heat insulation layer is smaller than the thermal conductivity of the thermal insulation buffer layer.

[0015] In a possible implementation, the temperature monitoring optical cable of the embodiment of the present application further includes at least one temperature-sensitive unit, which is arranged between the heat transfer layer and the thermal insulation buffer layer, and the pressure sensing unit extends along the length direction of the heating cable body and is configured to monitor the temperature of the heating cable body.

[0016] In a possible implementation manner, the temperature monitoring optical cable of the embodiment of the present application further includes:

[0017] The outer protective layer covers the temperature sensing layer, and the outer protective layer is provided with a groove portion at a position corresponding to the pressure sensing unit, and the groove portion is recessed toward the pressure sensing unit.

[0018] In a possible implementation, in the temperature monitoring optical cable of the embodiment of the present application, the heat transfer layer is evenly provided with a plurality of pressure sensing units along the circumferential direction, and the pressure sensing units are Bragg grating optical fibers.

[0019] In a possible implementation, in the temperature monitoring optical cable of the embodiment of the present application, the temperature sensing layer is a memory metal layer, and the heat transfer layer is a graphene foam layer.

[0020] In a possible implementation, in the temperature monitoring optical cable of the embodiment of the present application, the heating cable body includes a heating core and an insulation layer and a sheath layer sequentially sleeved on the heating core, and the heating core is a carbon fiber heating core.

[0021] On the other hand, an embodiment of the present application further provides a cable assembly, comprising a superconducting cable and any one of the temperature monitoring optical cables described above, wherein the temperature monitoring optical cable is wound around the superconducting cable.

[0022] The temperature monitoring optical cable and cable assembly provided in the present application utilize a heat transfer layer to cover a heating cable body in the temperature monitoring optical cable. The heat transfer layer transfers the heat of the heating cable body, so that the pressure sensing unit can be in a stable and suitable operating temperature range, thereby avoiding embrittlement of the pressure sensing unit due to the low temperature environment in which the superconducting cable is located, and ensuring stable operation and monitoring of the pressure sensing unit.

[0023] In addition, since the temperature sensing layer can directly sense the external temperature and apply pressure to the pressure sensing unit through temperature changes, the stress changes at each location correspond to the specific sensing area of ​​the pressure sensing unit, so that the pressure sensing unit can sense the exact location of the temperature mutation, with smaller monitoring errors and higher efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] Figure 1 This is a schematic diagram of the structure of the temperature monitoring optical cable in the embodiment of the present application;

[0026] Figure 2 This is an enlarged view of a portion of the structure of the temperature monitoring optical cable in the embodiment of the present application.

[0027] Description of Reference Numerals

[0028] 100, heating cable body; 101, heating core; 102, insulation layer; 103, sheath layer;

[0029] 200, heat transfer layer;

[0030] 300, pressure sensing unit;

[0031] 400, temperature sensing layer;

[0032] 500, thermal insulation buffer layer; 501, thermal insulation layer; 502, protruding part;

[0033] 600, outer protective layer; 601, groove portion.

[0034] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0035] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0036] As mentioned in the background technology, high-temperature superconducting cables are expected to break through the power transmission bottleneck of traditional cables due to their advantages such as low loss, small size and large transmission capacity. When high-temperature superconducting cables are working, the superconducting materials inside them must be kept at an extremely low temperature to achieve zero-resistance transmission of large currents. Therefore, superconducting materials are generally laid in liquid nitrogen pipelines to form a liquid nitrogen circulation loop together with superconducting cables. If there is a heat leakage source in the liquid nitrogen circulation loop, it will cause the superconducting cable to generate temperature rise, affecting the safe operation of the superconducting cable. Therefore, effective monitoring of the heat leakage condition of the superconducting cable is crucial.

[0037] In the related art, the method for monitoring the heat leakage condition of superconducting cables is generally to install sensors, such as temperature sensors, pressure sensors, etc., at key positions of the superconducting cables, and to determine whether there is a heat leakage problem by monitoring temperature changes and pressure fluctuations of the circulating cooling medium. Such point-like sensors can only monitor data at specific locations and are difficult to fully reflect the temperature distribution of the entire system, especially the entire length of the superconducting cable. The positioning of the leakage hotspot is not accurate enough, and the point-like distributed sensors have a slow response speed. They can only alarm when the heat leakage causes a significant increase in temperature or a significant decrease in pressure.

[0038] In addition, in ultra-low temperature environments, in order to protect the monitoring optical cables, insulation measures are usually taken to prevent the monitoring optical cables from being damaged, such as adding insulation layers and multi-layer composite structures. However, adding multiple insulation layers will reduce the sensitivity of the temperature monitoring optical cable to temperature perception. In an environment with complex heat exchange and heat dissipation conditions, it is relatively difficult for the temperature monitoring optical cable to accurately monitor the location and degree of temperature changes.

[0039] Based on the above related description, one or more embodiments of the present application provide a temperature monitoring optical cable and cable assembly. The temperature monitoring optical cable uses a heat transfer layer to cover the heating cable body. The heat transfer layer transfers the heat of the heating cable body, so that the pressure sensing unit can be in a stable and suitable working temperature range, avoiding the embrittlement of the pressure sensing unit due to the low temperature environment of the superconducting cable, and ensuring the stable operation and monitoring of the pressure sensing unit. In addition, because the temperature sensing layer can directly sense the external temperature and apply pressure to the pressure sensing unit through temperature changes, the stress change at each position corresponds to the specific sensing area of ​​the pressure sensing unit, so that the pressure sensing unit can sense the exact location of the temperature mutation, with smaller monitoring errors and higher efficiency.

[0040] The temperature monitoring optical cable and cable assembly according to the embodiments of the present application are described below with reference to the accompanying drawings.

[0041] like Figure 1 As shown, an embodiment of the present application provides a temperature monitoring optical cable, including a heating cable body 100 , a heat transfer layer 200 , at least one pressure sensing unit 300 and a temperature sensing layer 400 .

[0042] The heat transfer layer 200 covers the heating cable body 100 to transfer the heat of the heating cable body 100; at least one pressure sensing unit 300 is arranged on the outside of the heat transfer layer 200, and the pressure sensing unit 300 extends along the length direction of the heating cable body 100, and is configured to generate a strain signal when under pressure; the temperature sensing layer 400 covers the pressure sensing unit 300, and the temperature sensing layer 400 is configured to apply pressure to one side of the pressure sensing unit 300 due to temperature changes. When the pressure sensing unit 300 is under pressure, a strain signal is generated to feedback the temperature of the temperature sensing layer 400, and a thermal insulation buffer layer 500 is arranged between the temperature sensing layer 400 and the pressure sensing unit 300 to prevent the heat of the heating cable body 100 from being transmitted to the temperature sensing layer 400.

[0043] From the above description, it can be seen that in the temperature monitoring optical cable provided in the embodiment of the present application, the pressure sensing unit 300 extends along the length direction of the heating cable body 100. When the temperature sensing layer 400 applies pressure to the pressure sensing unit 300 due to temperature changes, the corresponding part of the pressure sensing unit 300 will generate a strain signal due to the pressure change. The pressure sensing unit 300 provides continuous strain changes rather than data of several discrete points in the related technology. Therefore, it is easier to capture small changes. The strain information of each point can correspond to the specific position of the optical fiber, thereby indirectly and quickly finding the location of the temperature abnormality point, timely repair, and improving the monitoring accuracy and efficiency.

[0044] In addition, since a heating cable body 100 is provided inside the temperature monitoring optical cable, the heating cable body 100 can provide heat for the pressure sensing unit 300, ensuring that the pressure sensing unit 300 is always within a stable temperature range, effectively preventing the optical fiber from becoming brittle due to low temperature, which is beneficial to ensuring that the pressure sensing unit 300 can operate normally.

[0045] It should be noted that the “outside” and “inside” mentioned in the embodiments of the present application are described relative to the radial direction of the temperature monitoring optical cable. Figure 1 For example, Figure 1 The heating cable body 100, the heat transfer layer 200, the pressure sensing unit 300 and the temperature sensing layer 400 are arranged in sequence from the inside to the outside, which will not be described in detail below.

[0046] like Figure 1 As shown, the heating cable body 100 in the embodiment of the present application includes a heating core 101 and an insulating layer 102 and a sheath layer 103 which are sequentially sleeved on the heating core 101 , and the heating core 101 is a carbon fiber heating core 101 .

[0047] Exemplarily, the heating core 101 can be woven or wound with carbon fiber materials, and the insulating layer 102 is wrapped around the outside of the carbon fiber heating core 101, and is usually made of high-temperature resistant and excellent insulating materials, such as silicone rubber, fluoroplastics, etc., to ensure the safe operation of the electric heating element and prevent short circuits and electric shock accidents. The sheath layer 103 is located outside the insulating layer 102, and mainly plays a protective and mechanical support role. Generally, heat-resistant, wear-resistant, and aging-resistant materials such as polyetheretherketone, polytetrafluoroethylene, silicone rubber, etc. are selected to adapt to the use under various harsh environmental conditions, ensuring that the cable can still maintain good mechanical and electrical properties under long-term high-temperature working conditions.

[0048] The heating cable body 100 converts electrical energy into thermal energy and transfers heat through heat conduction and infrared radiation. By adjusting the heating power, the internal environment of the temperature monitoring optical cable is kept in a relatively stable temperature range, thereby preventing the internal pressure sensing unit 300 from becoming brittle due to low temperature.

[0049] Compared with traditional metal heating cables, carbon fiber has higher thermoelectric efficiency and can save energy. Its non-metallic properties make the electromagnetic radiation relatively small, so there is no need to set up an additional electromagnetic shielding layer, and the use effect is better.

[0050] Here, illustratively, the heating cable body 100 transfers heat so that the temperature range of the pressure sensing unit 300 is between -20°C and 60°C. Of course, the heating power of the heating cable body 100 can be flexibly adjusted according to the actual use scenario of the temperature monitoring optical cable.

[0051] In some embodiments, the heat transfer layer 200 is a graphene foam layer, and the graphene foam layer is wrapped around the heating cable body 100 through a wrapping process. Graphene foam has the characteristics of high porosity. On the one hand, it is light in weight and has good mechanical properties. When squeezed by the temperature sensing layer 400, it can withstand a certain pressure and produce deformation, ensuring the integrity and stability of the overall structure, which is conducive to adapting to complex terrain or scenes. On the other hand, the high porosity design of graphene foam can quickly and efficiently transfer heat to the pressure sensing unit 300, ensuring that the pressure sensing unit 300 is in a suitable working temperature range. Therefore, the design of the heat transfer layer 200 can also reduce the pressure intensity caused by the temperature sensing layer 400, and protect the pressure sensing unit 300 and the heating cable body 100.

[0052] Generally, in order to balance the conduction efficiency and mechanical strength of the heat transfer layer 200, the porosity of the graphene foam layer is 50% to 80%, and the thickness is 0.5 to 1.0 mm. For example, the porosity of the graphene foam layer is 50%, 65% or 80%, and the thickness of the graphene foam layer is 0.5 mm, 0.8 mm or 1.0 mm.

[0053] like Figure 1 As shown, in some embodiments, the temperature monitoring optical cable also includes a thermal insulation buffer layer 500, which is arranged between the temperature sensing layer 400 and the pressure sensing unit 300 to block the heat of the heating cable body 100 from being transferred to the temperature sensing layer 400; the temperature sensing layer 400 applies pressure to one side of the pressure sensing unit 300 so that at least one of the thermal insulation buffer layer 500 and the heat transfer layer 200 is compressed and deformed by the pressure sensing unit 300.

[0054] The above-mentioned thermal insulation buffer layer 500 is located on the outside of the pressure sensing unit 300 and on the inside of the temperature sensing layer 400. The thermal insulation buffer layer 500 is preferably made of a thermal insulation material with a low thermal conductivity coefficient to isolate the temperature difference between the inside and the outside as much as possible and prevent the external temperature from affecting the internal pressure sensing unit 300. Exemplarily, the thermal insulation buffer layer 500 is made of rock wool, aerogel felt or polystyrene foam material.

[0055] It should be noted that, since the thermal insulation buffer layer 500 is located between the temperature sensing layer 400 and the pressure sensing unit 300, the deformation of the temperature sensing layer 400 is transmitted to the pressure sensing unit 300 through the thermal insulation buffer layer 500, and therefore, the thickness of the thermal insulation buffer layer 500 should be relatively small to prevent the thickness from being too large and affecting the sensing sensitivity of the pressure sensing unit 300. Exemplarily, the thermal insulation buffer layer 500 is wrapped around the pressure sensing unit 300 by a wrapping process, and the thickness is 1.0-2.0 mm, for example, the thickness of the thermal insulation buffer layer 500 is 1 mm, 1.2 mm or 2 mm.

[0056] Depend on Figure 1 It can also be seen that when the temperature sensing layer 400 is subjected to pressure due to temperature changes, since the heat transfer layer 200 adopts a high-porosity graphene foam material, the thermal insulation buffer layer 500 and the heat transfer layer 200 are deformed due to the squeezing effect of the temperature sensing layer 400. This design can also better fix the pressure sensing unit 300, which is beneficial to enhancing the limiting constraint effect on the pressure sensing unit 300.

[0057] Furthermore, in some embodiments, a side of the thermal insulation buffer layer 500 facing the temperature sensing layer 400 is also coated with a heat insulation layer 501 , and the thermal conductivity of the heat insulation layer 501 is smaller than the thermal conductivity of the thermal insulation buffer layer 500 .

[0058] Exemplarily, the thermal conductivity of the heat preservation buffer layer 500 is generally 0.030 W / m•K, and the thermal conductivity of the heat insulation layer 501 is lower than 0.030 W / m•K, for example, nano aerogel, ZS-1 high temperature resistant heat insulation material, etc. The coating thickness of the heat insulation layer 501 is generally 100~200 um, for example, 100 um, 150 um or 200 um. By providing the heat insulation layer 501, the heat preservation and heat insulation effect of the heat preservation buffer layer 500 can be further improved, the temperature inside and outside the pressure sensing unit 300 can be isolated, and the heat transferred by the heating cable body 100 can be retained inside, so as to maintain the working temperature range of the pressure sensing unit 300.

[0059] like Figure 2 As shown, in the embodiment of the present application, the thermal insulation buffer layer 500 is protruded toward the temperature sensing layer 400 at the position corresponding to the pressure sensing unit 300, the protruding portion 502 of the thermal insulation buffer layer 500 is connected to the temperature sensing layer 400, and the thermal insulation buffer layer 500 and the temperature sensing layer 400 are separated by the protruding portion 502 to form a cavity.

[0060] Here, the thickness of the heat insulation layer 501 itself is relatively thin, and does not affect the sensing sensitivity of the pressure sensing unit 300 when the temperature sensing layer 400 applies pressure. As an alternative embodiment, the heat insulation layer 501 is only provided on the protruding portion 502 of the heat preservation buffer layer 500, and the other portions of the heat preservation buffer layer 500 are not provided with the heat insulation layer 501, so as to reduce the thickness of the heat preservation buffer layer 500 as much as possible while ensuring the coupling effect of the heat preservation buffer layer and the temperature sensing layer 400.

[0061] Since the thermal insulation buffer layer 500 and the heat transfer layer 200 have a certain deformation ability and the thickness of the thermal insulation buffer layer 500 is relatively thin, when the temperature sensing layer 400 applies pressure to the inside, the thermal insulation buffer layer 500 and the heat transfer layer 200 deform at the position corresponding to the pressure sensing unit 300 to adapt to the pressure sensing unit 300, so that the protruding portion 502 of the thermal insulation buffer layer 500 contacts the temperature sensing layer 400, and the other parts outside the protruding portion 502 are arranged smoothly along the edge. Therefore, the entire cavity is bounded by the protruding portion 502 of the thermal insulation buffer layer 500, the inner side of the cavity is the thermal insulation buffer layer 500, and the outer side is the temperature sensing layer 400.

[0062] The design of the cavity can further block the conduction of internal heat to the temperature sensing layer 400, reducing the impact of internal high temperature on the temperature sensing layer 400. In some embodiments, when the thermal insulation layer 501 is coated on the outside of the thermal insulation buffer layer 500, the thermal insulation layer 501 is directly bonded and fixed to the temperature sensing layer 400. This design can make the thermal insulation buffer layer 500 have a good supporting effect, thereby enhancing the overall stability of the temperature monitoring optical cable.

[0063] In some embodiments, the heat transfer layer 200 is evenly provided with a plurality of pressure sensing units 300 along the circumferential direction, and the pressure sensing units 300 are Bragg grating optical fibers.

[0064] Bragg grating optical fiber reflects light of a specific wavelength and transmits light of other wavelengths, thereby achieving precise control and measurement of optical signals. When the pressure sensing unit 300 is subjected to external stress, the period and refractive index of the grating change, causing the Bragg reflection wavelength to shift. By measuring this wavelength shift, the magnitude and direction of the stress can be accurately determined, thereby achieving highly sensitive stress monitoring.

[0065] Here, the pressure sensing unit 300 may use a low-loss anti-bending optical fiber, and the outer surface of the optical fiber is coated with a plastic layer as a protective layer. The plastic layer is a high molecular polymer with excellent bending performance, and commonly used materials include polyester elastomer, thermoplastic elastomer, polyolefin, etc.

[0066] As an alternative implementation, the pressure sensing unit 300 may also use a long period fiber grating (LPFG), or the pressure sensing unit 300 may use other monitoring devices that can respond to strain changes, such as a phase-sensitive optical time domain reflectometer (φ-OTDR). For different application scenarios, the pressure sensing unit 300 may flexibly select different types of devices, and this is not absolutely limited in the embodiments of the present application.

[0067] The outer diameter of the pressure sensing unit 300 can be set according to the size of the temperature monitoring optical cable. For example, the outer diameter of the pressure sensing unit 300 is 0.85-0.95 mm. Generally, the outer diameter of the pressure sensing unit 300 is 0.85 mm, 0.9 mm or 0.95 mm.

[0068] There is no absolute limit on the actual number of pressure sensing units 300, which can be selected according to the monitoring function and the sensitivity to the surrounding environment. For example, in the embodiment of the present application, there are four pressure sensing units 300 arranged symmetrically.

[0069] Multiple pressure sensing units 300 are evenly arranged along the circumference of the heat transfer layer 200, so that the lateral extrusion pressure of the temperature monitoring optical cable in different directions can be sensed. By comparing the strain signals of the pressure sensing units 300 at different positions, the temperature abnormality area of ​​the temperature monitoring optical cable can be located quickly and accurately, thereby improving the overall monitoring accuracy and efficiency of the temperature monitoring optical cable.

[0070] In some embodiments, the temperature monitoring optical cable further includes at least one temperature sensitive unit, which is disposed between the heat transfer layer 200 and the thermal insulation buffer layer 500 . The temperature sensitive unit extends along the length direction of the heating cable body 100 and is configured to monitor the temperature of the heating cable body 100 .

[0071] The above-mentioned temperature-sensitive unit can be selected with reference to the type of pressure sensing unit 300. When the temperature-sensitive unit adopts Bragg grating optical fiber, when the temperature-sensitive unit is subjected to temperature changes, the period and refractive index of the grating will change, resulting in a shift in the Bragg reflection wavelength. By measuring this wavelength shift, the temperature change can be accurately determined, thereby achieving high-sensitivity temperature monitoring. That is, the temperature-sensitive unit and the pressure sensing unit 300 can use the same optical fiber type, but have different functions.

[0072] Here, by setting up a temperature-sensitive light unit, it is possible to facilitate temperature monitoring and adjustment inside the thermal insulation buffer layer 500. The temperature inside the thermal insulation buffer layer 500 can be known based on the monitored temperature, so that the heating power of the heating cable body 100 can be adjusted in real time according to the temperature inside the thermal insulation buffer layer 500, thereby ensuring that the pressure sensing unit 300 is maintained in a suitable operating temperature range, and ensuring that the pressure sensing unit 300 can maintain the continuity and stability of signal transmission under various complex working conditions.

[0073] It can also be seen from the above description that the temperature-sensitive unit and the pressure sensing unit 300 can use the same optical fiber or different optical fibers. The working principle of the Bragg grating fiber (FBG) is that the Bragg grating formed by the periodic refractive index change in the optical fiber reflects light of a specific wavelength (Bragg wavelength), and the reflected wavelength will change with the change of the external environment (such as temperature, pressure, strain, etc.). Therefore, the Bragg grating fiber responds to both temperature and pressure strain and has a certain cross-sensitivity. When the Bragg grating fiber is used as a detection unit with different functions, it is necessary to make a certain distinction. Exemplarily, when the Bragg grating fiber is used as a temperature-sensitive unit, it can be encapsulated in a flexible thermosensitive material so that it is not affected by external strain factors. When the Bragg grating fiber is used as a pressure sensing unit 300, it needs to maintain a firmly embedded state so that it can sensitively sense external strain. In general, due to the divergent heat transfer of the heating cable body 100, a temperature-sensitive unit can monitor the temperature inside the thermal insulation buffer layer 500.

[0074] like Figure 1 As shown, in the embodiment of the present application, the temperature sensing layer 400 is a memory metal layer. Furthermore, the temperature sensing layer 400 is a NiTi alloy (Nickel-Titanium Alloy) with shape memory and superelasticity. The nickel-titanium alloy has a reversible phase change characteristic, that is, the transition between the austenite phase and the martensite phase. At an ultra-low temperature of 77k (-196.15°C), the NiTi alloy is in a martensite phase state and has high plasticity. The alloy can be plastically deformed without causing permanent damage.

[0075] If heat leakage occurs in the low-temperature cooling medium environment where the superconducting cable is located, the NiTi alloy is heated from 77 K back to room temperature, and the NiTi alloy undergoes a reverse transformation from the martensite phase to the austenite phase, and the NiTi alloy spontaneously recovers to its original shape. During this process, the volume shrinkage decreases, and the compressive stress of the thermal insulation buffer layer 500 and the pressure sensing unit 300 connected thereto at 77 K is released, and the strain signal of the pressure sensing unit 300 will change, thereby locating the position and degree of the temperature change. At the same time, when an abnormality occurs in the outside world, the heated NiTi alloy is in the austenite state, and its high elasticity, good strength and stability play a certain protective role on the internal structure.

[0076] The temperature sensing layer 400 is coated on the outside of the thermal insulation buffer layer 500 by a longitudinal wrapping process, so that the temperature sensing layer 400 is connected to the heat insulation layer 501 on the thermal insulation buffer layer 500. This design enables the temperature sensing layer 400 and the thermal insulation buffer layer 500 to form a good coupling effect. When the temperature sensing layer 400 is deformed by temperature changes, it is effectively transmitted to the thermal insulation buffer layer 500 and the pressure sensing unit 300 to generate a strain signal.

[0077] In order to achieve maximum sensitivity to temperature changes to ensure good thermal response and precise control of phase change temperature while maintaining sufficient mechanical stability and repeatability, the thickness of the temperature sensing layer 400 is between 100 and 500 um; illustratively, the thickness of the temperature sensing layer 400 is 100 um, 300 um or 500 um.

[0078] As an alternative implementation, the temperature sensing layer 400 may also be made of other reversible phase change memory alloy materials, such as copper-aluminum-nickel memory alloy, copper-zinc-nickel memory alloy, etc., which is not absolutely limited in the embodiments of the present application.

[0079] In some embodiments, the temperature monitoring optical cable further includes an outer sheath 600 , which covers the temperature sensing layer 400 . The outer sheath 600 is provided with a groove 601 at a position corresponding to the pressure sensing unit 300 , and the groove 601 is recessed toward the pressure sensing unit 300 .

[0080] The outer sheath 600 is located at the outermost side of the temperature monitoring optical cable to ensure that the temperature monitoring optical cable does not deform or break in an ultra-low temperature environment. For example, the outer sheath 600 can be made of materials with excellent properties such as polyurethane, thermoplastic polyolefin, polytetrafluoroethylene, silicone rubber, polyimide, etc. The overall thickness of the outer sheath 600 is generally 1.0-1.5 mm. For example, the thickness of the outer sheath 600 is 1 mm, 1.2 mm or 1.5 mm.

[0081] Depend on Figure 1 It can also be seen that the groove portion 601 is recessed toward the pressure sensing unit 300. The design of the groove portion 601 reduces the thickness of this area relative to other areas of the outer protective layer 600, thereby reducing the barrier to the induction of external environmental changes, allowing the temperature sensing layer 400 and the pressure sensing unit 300 to interact with the environment more directly, and enhancing the sensitivity of the temperature sensing layer 400 to ambient temperature fluctuations, thereby ensuring that the system can accurately capture subtle changes in the outside world and achieve high-precision environmental perception and detection.

[0082] In another embodiment of the present application, a cable assembly is provided, including a superconducting cable and a temperature monitoring optical cable in any of the above embodiments, wherein the temperature monitoring optical cable is wound around the superconducting cable.

[0083] The superconducting cable is immersed in the liquid nitrogen channel, and the temperature monitoring optical cable is wound on the superconducting cable. When heat leakage occurs in the liquid nitrogen channel, the temperature sensing layer 400 in the corresponding area of ​​the temperature monitoring optical cable is deformed by the temperature change, causing the stress signal of the pressure sensing unit 300 to change accordingly. The location of the heat leakage source is confirmed by monitoring the position of the stress signal change of the pressure sensing unit 300.

[0084] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0085] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A temperature monitoring optical cable, characterized in that: include: Heating cable body (100); A heat transfer layer (200), covering the heating cable body (100) to transfer heat from the heating cable body (100); At least one pressure sensing unit (300) is arranged outside the heat transfer layer (200), and the pressure sensing unit (300) extends along the length direction of the heating cable body (100); a temperature sensing layer (400) covering the pressure sensing unit (300), the temperature sensing layer (400) being configured to apply pressure to one side of the pressure sensing unit (300) in response to temperature changes, so that the pressure sensing unit (300) generates a strain signal when the pressure is applied, so as to provide feedback on the temperature of the temperature sensing layer (400); A heat-insulating buffer layer (500) is provided between the temperature sensing layer (400) and the pressure sensing unit (300) and is used to prevent heat from the heating cable body (100) from being transferred to the temperature sensing layer (400).

2. The temperature monitoring optical cable according to claim 1, characterized in that: The thermal insulation buffer layer (500) is arranged to protrude toward the temperature sensing layer (400) at a position corresponding to the pressure sensing unit (300); a protruding portion (502) of the thermal insulation buffer layer (500) is connected to the temperature sensing layer (400); and the thermal insulation buffer layer (500) and the temperature sensing layer (400) are separated by the protruding portion (502) to form a cavity.

3. The temperature monitoring optical cable according to claim 2, characterized in that: A side of the thermal insulation buffer layer (500) facing away from the pressure sensing unit (300) is coated with a thermal insulation layer (501), or a protruding portion (502) of the thermal insulation buffer layer (500) is provided with a thermal insulation layer (501).

4. The temperature monitoring optical cable according to claim 3, characterized in that: The heat insulating layer (501) is in contact with the temperature sensing layer (400), and the heat conductivity of the heat insulating layer (501) is smaller than the heat conductivity of the thermal insulation buffer layer (500).

5. The temperature monitoring optical cable according to claim 2, characterized in that: It also comprises at least one temperature-sensitive light unit, which is arranged between the heat transfer layer (200) and the heat-insulating buffer layer (500), and extends along the length direction of the heating cable body (100), and is configured to monitor the temperature of the heating cable body (100).

6. The temperature monitoring optical cable according to any one of claims 1 to 5, characterized in that: Also includes: An outer protective layer (600) covers the temperature sensing layer (400), and a groove portion (601) is provided on the outer protective layer (600) at a position corresponding to the pressure sensing unit (300), and the groove portion (601) is recessed toward the pressure sensing unit (300).

7. The temperature monitoring optical cable according to any one of claims 1 to 5, characterized in that: The heat transfer layer (200) is evenly provided with a plurality of pressure sensing units (300) along the circumferential direction, and the pressure sensing units (300) are Bragg grating optical fibers.

8. The temperature monitoring optical cable according to any one of claims 1 to 5, characterized in that: The temperature sensing layer (400) is a memory metal layer, and the heat transfer layer (200) is a graphene foam layer.

9. The temperature monitoring optical cable according to any one of claims 1 to 5, characterized in that: The heating cable body (100) comprises a heating core (101) and an insulating layer (102) and a sheath layer (103) which are sequentially sleeved on the heating core (101); the heating core (101) is a carbon fiber heating core (101).

10. A cable assembly, characterized in that: The invention comprises a superconducting cable and the temperature monitoring optical cable according to any one of claims 1 to 9, wherein the temperature monitoring optical cable is wound around the superconducting cable.

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