Temperature Monitoring Optical Cable and Cable Assembly

Abstract

An embodiment of the present application provides a temperature monitoring optical cable and a cable assembly, belonging to the field of optical cables. The temperature monitoring optical cable includes a heating cable body, a heat transfer layer, at least one pressure sensing unit, a thermal insulation buffer layer, and a temperature sensing layer. The heat transfer layer covers the heating cable body to transfer the heat of the heating cable body; the pressure sensing unit is arranged on the outer side of the heat transfer layer, and the pressure sensing unit extends along the length direction of the heating cable body; the temperature sensing layer covers the pressure sensing unit, and the temperature sensing layer is configured to apply pressure to the pressure sensing unit side due to temperature changes, and the pressure sensing unit generates a strain signal when it is under pressure to feedback the temperature of the temperature sensing layer. The thermal insulation buffer layer is used to block the heat transmission of the heating cable body to the temperature sensing layer. The temperature monitoring optical cable provided by the embodiment of the present application can continuously and uninterruptedly monitor the ambient temperature of the superconducting cable of the cable assembly, and improve the monitoring accuracy of the working temperature of the superconducting cable.

Description

Technical Field

[0001] This application relates to the technical field of optical cables, and particularly 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 volume, and have good development prospects in specific large-capacity power transmission applications.

[0003] In related technologies, superconducting cables are generally arranged in an environment of a low-temperature cooling medium. The temperature monitoring method of superconducting cables usually installs sensors at its key parts, such as temperature sensors, pressure sensors, etc., and judges whether there is a heat leakage problem by monitoring the temperature change and the pressure fluctuation of the circulating cooling medium.

[0004] However, the sensor components are difficult to comprehensively reflect the temperature distribution of the entire system, especially the entire length of the superconducting cable, and the temperature sensor has a slow response speed, and can only alarm when the heat leakage problem causes a significant increase in temperature or a significant decrease in pressure, and the monitoring accuracy is poor. Summary of the Invention

[0005] This application provides a temperature monitoring optical cable and a cable assembly to solve the technical problems of poor temperature monitoring accuracy of the detection sensors arranged on the superconducting cable and difficulty in positioning the heat leakage source location in related technologies.

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

[0007] A heating cable body;

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

[0009] At least one pressure sensing unit, arranged on the outer side of 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, and the temperature sensing layer is configured to apply pressure to the side of the pressure sensing unit under the influence of temperature change, and the pressure sensing unit generates a strain signal when receiving the pressure to feedback the temperature of the temperature sensing layer;

[0011] A heat preservation and buffer layer, arranged between the temperature sensing layer and the pressure sensing unit to block the heat transmission of the heating cable body 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 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 by this application utilize a heat transfer layer to wrap the heating cable body in the temperature monitoring optical cable. The heat transfer layer transfers the heat of the heating cable body, enabling the pressure sensing unit to be within a stable and suitable operating temperature range, avoiding 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.

[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 change at each location corresponds to the specific sensing area of the pressure sensing unit, enabling the pressure sensing unit to sense the exact location of temperature mutation with smaller monitoring error and higher efficiency. Brief Description of the Drawings

[0024] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0025] Figure 1 It is a schematic structural diagram of the temperature monitoring optical cable in the embodiment of this application;

[0026] Figure 2 It is an enlarged partial structural diagram of the temperature monitoring optical cable in the embodiment of this application.

[0027] Description of the Reference Numerals in the Drawings

[0028] 100, heating cable body; 101, heating core; 102, insulating 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, heat insulation layer; 502, protruding part;

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

[0034] Through the above drawings, specific embodiments of this application have been shown, and there will be more detailed descriptions later. These drawings and textual descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. Detailed Description of the Embodiments

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

[0036] As described in the background art, 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 volume, and large transmission capacity. When a high-temperature superconducting cable is in operation, the superconducting material inside it must be maintained at an extremely low temperature to achieve zero-resistance transmission of large currents. Therefore, the superconducting material is generally laid in a liquid nitrogen pipeline to form a liquid nitrogen circulation loop together with the superconducting cable. If there is a heat leakage source in the liquid nitrogen circulation loop, it will cause the temperature rise of the superconducting cable and affect 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 general method for monitoring the heat leakage condition of a superconducting cable is to install sensors, such as temperature sensors, pressure sensors, etc., at key parts of the superconducting cable. By monitoring the temperature change and the pressure fluctuation of the circulating cooling medium, it is judged whether there is a heat leakage problem. Such point-like arranged sensors can only monitor the data at specific positions, and it is difficult to comprehensively reflect the temperature distribution of the entire system, especially the full length of the superconducting cable. The positioning of the heat leakage point is not accurate enough, and the response speed of the point-like distributed sensors is slow. Only when the heat leakage causes a significant temperature rise or a significant pressure drop can an alarm be issued.

[0038] In addition, in an ultra-low temperature environment, in order to protect the monitoring optical cable, heat preservation measures are usually taken to avoid damage to the monitoring optical cable, such as adding a heat preservation layer and multi-layer composite structures. However, the method of adding multiple heat preservation 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 position and degree of temperature change.

[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 arranged 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, and being beneficial to ensuring the normal operation of the pressure sensing unit 300.

[0045] It should be noted that the "outer side" and "inner side" mentioned in the embodiments of the present application are described relative to the radial direction of the temperature monitoring optical cable. Taking Figure 1 as an 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 elaborated hereinafter.

[0046] As Figure 1 shown, the heating cable body 100 in the embodiments of the present application includes a heating core 101, an insulating layer 102 and a sheath layer 103 that 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 made by weaving or winding carbon fiber materials. The insulating layer 102 is wrapped outside the carbon fiber heating core 101 and is usually made of materials with high temperature resistance and excellent insulation properties, such as silicone rubber and fluoroplastics, to ensure the safe operation of the electrothermal element and prevent the occurrence of short circuits and electric shock accidents. The sheath layer 103 is located outside the insulating layer 102 and mainly plays a role in protection and mechanical support. Generally, materials with heat resistance, wear resistance, and aging resistance, such as polyether ether ketone, polytetrafluoroethylene, and silicone rubber, are selected to adapt to the use under various harsh environmental conditions and ensure that the cable can still maintain good mechanical properties and electrical properties under long-term high-temperature working conditions.

[0048] The heating cable body 100 converts electrical energy into heat energy and transfers heat through the ways of heat conduction and infrared radiation. By regulating the heating power, the internal environment of the temperature monitoring optical cable is maintained in a relatively stable temperature range, avoiding embrittlement of the internal pressure sensing unit 300 due to low temperature.

[0049] Compared with traditional metal heating cables, carbon fiber has higher thermoelectric efficiency, can save energy consumption, and its non-metallic property results in relatively small electromagnetic radiation, eliminating the need to set up an additional electromagnetic shielding layer, with better use effects.

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

[0051] In some embodiments, the heat transfer layer 200 is a graphene foam layer, and the graphene foam layer wraps the heating cable 100 through a winding process. The graphene foam has the characteristics of high porosity. On the one hand, it is lighter in weight and has good mechanical properties. When squeezed by the temperature sensing layer 400, it can withstand a certain pressure and deform, ensuring the integrity and stability of the overall structure, which is beneficial to adapting to complex terrains or scenarios. On the other hand, the high-porosity design of the graphene foam can quickly and efficiently conduct heat to the pressure sensing unit 300, ensuring that the pressure sensing unit 300 is in a suitable working temperature range. Therefore, designing the heat transfer layer 200 can also reduce the pressure intensity brought by the temperature sensing layer 400 and protect the pressure sensing unit 300 and the heating cable 100.

[0052] Generally, to balance the conduction efficiency and mechanical strength of the heat transfer layer 200, the porosity of the graphene foam layer is 50% - 80%, and its thickness is 0.5 - 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] As Figure 1 shown, in some embodiments, the temperature monitoring optical cable further includes a thermal insulation buffer layer 500, and the thermal insulation buffer layer 500 is disposed between the temperature sensing layer 400 and the pressure sensing unit 300 to block the heat transfer of the heating cable 100 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 deformed by the pressure of the pressure sensing unit 300.

[0054] The above-mentioned thermal insulation buffer layer 500 is located outside the pressure sensing unit 300 and inside the temperature sensing layer 400. The thermal insulation buffer layer 500 is preferably made of a thermal insulation material with a low thermal conductivity to isolate the temperature difference between the inside and 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. Therefore, the thickness of the thermal insulation buffer layer 500 should be as small as possible 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 wraps around the pressure sensing unit 300 through a winding 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] ByFigure 1 It can also be seen that when the temperature sensing layer 400 is pressured by temperature changes, since the heat transfer layer 200 uses a graphene foam material with a high porosity, both the heat preservation buffer layer 500 and the heat transfer layer 200 are deformed due to the extrusion of the temperature sensing layer 400. This design can also better fix the pressure sensing unit 300, which is beneficial to enhancing the limiting and constraining effect on the pressure sensing unit 300.

[0057] Furthermore, in some embodiments, a heat insulation layer 501 is further coated on the side of the heat preservation buffer layer 500 facing the temperature sensing layer 400, and the thermal conductivity of the heat insulation layer 501 is less than that of the heat preservation 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 heat insulation and heat preservation materials, etc. The coating thickness of the heat insulation layer 501 is generally 100~200 um, such as 100 um, 150 um or 200 um. By setting the heat insulation layer 501, the heat preservation and heat insulation effect of the heat preservation buffer layer 500 can be further improved, isolating the temperature inside and outside the pressure sensing unit 300, and retaining the heat transferred by the heating cable 100 inside, so as to maintain the working temperature range of the pressure sensing unit 300.

[0059] As Figure 2 shown, in the embodiment of the present application, the position of the heat preservation buffer layer 500 corresponding to the pressure sensing unit 300 protrudes towards the temperature sensing layer 400. The protruding part 502 of the heat preservation buffer layer 500 is connected to the temperature sensing layer 400, and a cavity is formed by separating the heat preservation buffer layer 500 and the temperature sensing layer 400 with the protruding part 502.

[0060] Here, the heat insulation layer 501 itself has a relatively thin thickness and does not affect the sensing sensitivity of the pressure sensing unit 300 when the temperature sensing layer 400 exerts pressure. As an alternative embodiment, the heat insulation layer 501 is only provided on the protruding part 502 of the heat preservation buffer layer 500, and the heat insulation layer 501 is not provided on other parts of the heat preservation buffer layer 500, so as to reduce the thickness of the heat preservation buffer layer 500 as much as possible on the premise of ensuring the coupling effect between 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 inward, the positions of the thermal insulation buffer layer 500 and the heat transfer layer 200 corresponding to the pressure sensing unit 300 are deformed to adapt to the pressure sensing unit 300, so that the protruding part 502 of the thermal insulation buffer layer 500 contacts the temperature sensing layer 400, and the other parts outside the protruding part 502 are arranged smoothly along. Thus, the whole cavity is bounded by the protruding part 502 of the thermal insulation buffer layer 500, with the thermal insulation buffer layer 500 on the inner side of the cavity and the temperature sensing layer 400 on the outer side.

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

[0063] In some embodiments, a plurality of pressure sensing units 300 are uniformly arranged along the circumferential direction of the heat transfer layer 200, and the pressure sensing unit 300 is a fiber Bragg grating.

[0064] The fiber Bragg grating 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, resulting in a shift of the Bragg reflection wavelength. By measuring this wavelength shift, the magnitude and direction of the stress can be accurately determined, thereby achieving high-sensitivity stress monitoring.

[0065] Here, the pressure sensing unit 300 can adopt a low-loss bend-resistant optical fiber, and a plastic layer is coated outside the optical fiber as a protective layer. The plastic layer is a high molecular polymer with excellent bending performance, and common materials such as polyester elastomer, thermoplastic elastomer, polyolefin, etc.

[0066] As an alternative implementation, the pressure sensing unit 300 can also adopt a long-period fiber grating (LPFG), or the pressure sensing unit 300 adopts other monitoring devices capable of reflecting strain changes, such as a phase-sensitive optical time domain reflectometer (φ-OTDR). For different application scenarios, different device types can be flexibly selected for the pressure sensing unit 300, and this application embodiment does not make an absolute limitation on this.

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

[0068] The actual arrangement quantity of the pressure sensing unit 300 is not absolutely limited, and can be selected according to the monitoring function and the perception sensitivity to the surrounding environment. Exemplarily, in the embodiment of the present application, the pressure sensing unit 300 has four symmetrically arranged ones.

[0069] A plurality of pressure sensing units 300 are evenly arranged along the circumferential direction of the heat transfer layer 200, so that the temperature monitoring optical cable can sense the lateral extrusion forces in different directions. By comparing the strain signals of the pressure sensing units 300 at different positions, it is also possible to quickly and accurately locate the temperature abnormal area of the temperature monitoring optical cable, thereby improving the overall monitoring accuracy and monitoring efficiency of the temperature monitoring optical cable.

[0070] In some embodiments, the monitored temperature monitoring optical cable further includes at least one temperature-sensitive optical unit. The temperature-sensitive optical unit is arranged between the heat transfer layer 200 and the thermal insulation buffer layer 500, and the temperature-sensitive optical 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 optical unit can be selected with reference to the type of the pressure sensing unit 300. When the temperature-sensitive optical unit adopts a fiber Bragg grating, when the temperature-sensitive optical unit is affected by temperature changes, the period and refractive index of the grating will change, resulting in a shift of the Bragg reflection wavelength. By measuring this wavelength shift, the temperature change can be accurately determined, thereby realizing high-sensitivity temperature monitoring. That is to say, the optical fiber type adopted by the temperature-sensitive optical unit and the pressure sensing unit 300 can be the same, but the functions are different.

[0072] Here, by setting the temperature-sensitive optical unit, it is convenient to monitor and adjust the temperature inside the thermal insulation buffer layer 500. The temperature inside the thermal insulation buffer layer 500 can be obtained according to the monitored temperature, and thus 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, so as to ensure that the pressure sensing unit 300 maintains in a suitable working temperature range and ensure the continuity and stability of signal transmission of the pressure sensing unit 300 under various complex working conditions.

[0073] As can also be seen from the above description, the temperature-sensitive optical unit and the pressure sensing unit 300 can use the same optical fiber or different optical fibers. The working principle of Fiber Bragg Grating (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 changes with the change of the external environment (such as temperature, pressure, strain, etc.). Therefore, the Fiber Bragg Grating has a response to both temperature and pressure strain and has a certain cross-sensitivity. When the Fiber Bragg Grating is used as a detection unit with different functions, certain distinctions need to be made. Exemplarily, when the Fiber Bragg Grating is used as a temperature-sensitive optical unit, it can be encapsulated in a flexible thermosensitive material to make it unaffected by external strain factors. When the Fiber Bragg Grating is used as the pressure sensing unit 300, it needs to be firmly embedded to make it sensitive to external strain. Generally, due to the heat dissipation transfer of the heating cable 100, one temperature-sensitive optical unit can monitor the temperature inside the thermal insulation buffer layer 500.

[0074] As Figure 1 shown, in the embodiment of the present application, the temperature sensing layer 400 is a shape memory metal layer. Further, the temperature sensing layer 400 is a NiTi alloy (Nickel-Titanium Alloy) with shape memory and superelasticity. The NiTi alloy has a reversible phase change characteristic, that is, the transformation between the austenite phase and the martensite phase. At a cryogenic temperature of 77K (-196.15 °C), the NiTi alloy is in the martensite phase state and has high plasticity. The alloy can undergo plastic deformation without causing permanent damage.

[0075] If there is a heat leakage problem in the cryogenic cooling medium environment where the superconducting cable is located, the NiTi alloy is heated from 77K back to room temperature, and the NiTi alloy will undergo an inverse transformation from the martensite phase back to the austenite phase. The NiTi alloy spontaneously returns 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 to it in the 77K state is released. The strain signal of the pressure sensing unit 300 will change, so as to locate the position and degree of temperature change. At the same time, when an abnormality occurs outside, the heated NiTi alloy is in the austenite state, and its high elasticity, good strength and stability play a certain protective role for 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 around the superconducting cable. When there is a heat leakage problem in the liquid nitrogen channel, the temperature sensing layer 400 in the corresponding area of the temperature monitoring optical cable deforms due to the temperature change, causing the stress signal of the pressure sensing unit 300 to change accordingly. The position of the heat leakage source is confirmed by monitoring the change position of the stress signal of the pressure sensing unit 300.

[0084] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include known common knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the following claims.

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

Claims

1. A temperature monitoring optical cable, characterized in that, Comprising: A heating cable body (100); A heat transfer layer (200), covering the heating cable body (100) to transfer the heat of the heating cable body (100); At least one pressure sensing unit (300), disposed 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), and the temperature sensing layer (400) is configured to apply pressure to the side of the pressure sensing unit (300) under temperature change, and when the pressure sensing unit (300) receives the pressure, a strain signal is generated to feedback the temperature of the temperature sensing layer (400); A heat preservation and buffer layer (500), disposed between the temperature sensing layer (400) and the pressure sensing unit (300) to block the heat transfer of the heating cable body (100) to the temperature sensing layer (400); the position of the heat preservation and buffer layer (500) corresponding to the pressure sensing unit (300) protrudes towards the temperature sensing layer (400), the protruding part (502) of the heat preservation and buffer layer (500) is connected to the temperature sensing layer (400), and the heat preservation and buffer layer (500) and the temperature sensing layer (400) are separated by the protruding part (502) to form a cavity; It further includes at least one temperature and light sensing unit, and the temperature and light sensing unit is disposed between the heat transfer layer (200) and the heat preservation and buffer layer (500), and the temperature and light sensing 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).

2. The temperature monitoring optical cable according to claim 1, characterized in that, One side of the heat preservation and buffer layer (500) facing away from the pressure sensing unit (300) is coated with a heat insulation layer (501), or the protruding part (502) of the heat preservation and buffer layer (500) is provided with a heat insulation layer (501).

3. The temperature monitoring optical cable according to claim 2, characterized in that, The heat insulation layer (501) abuts against the temperature sensing layer (400), and the thermal conductivity coefficient of the heat insulation layer (501) is less than that of the heat preservation and buffer layer (500).

4. The temperature monitoring optical cable according to any one of claims 1 to 3, characterized in that, It further includes: An outer protection layer (600), covering the temperature sensing layer (400), and a groove part (601) is provided at the position of the outer protection layer (600) corresponding to the pressure sensing unit (300), and the groove part (601) is recessed towards the pressure sensing unit (300).

5. The temperature monitoring optical cable according to any one of claims 1 to 3, characterized in that, A plurality of pressure sensing units (300) are uniformly arranged along the circumferential direction of the heat transfer layer (200), and the pressure sensing unit (300) is a fiber Bragg grating.

6. The temperature monitoring optical cable according to any one of claims 1 to 3, characterized in that, The temperature sensing layer (400) is a shape memory alloy layer, and the heat transfer layer (200) is a graphene foam layer.

7. The temperature monitoring optical cable according to any one of claims 1 to 3, characterized in that, The heating cable body (100) includes a heating core (101), an insulating layer (102) and a sheath layer (103) sequentially sleeved on the heating core (101), and the heating core (101) is a carbon fiber heating core (101).

8. A cable assembly, characterized in that, Comprising a superconducting cable and the temperature monitoring optical cable according to any one of claims 1 to 7, and the temperature monitoring optical cable is wound around the superconducting cable.

Images