A smart de-icing tether cable and its preparation method

Abstract

This invention relates to the field of special cables and intelligent control technology, specifically to an intelligent de-icing tethered cable and its manufacturing method. The cable comprises, arranged radially from the inside out, a power transmission unit, a distributed sensing optical fiber, a thermally conductive insulating pad, a double-layer load-bearing armor layer, a microcapsule phase change heat sink layer, a heat-oriented reflective layer, a segmented controllable heating layer, a high-strength fiber braided layer, an outer sheath, and a surface anti-icing coating. The heat-oriented reflective layer and the microcapsule phase change heat sink layer form a series thermal resistance structure. This invention uses the heat-oriented reflective layer to forcibly reflect PTC heat outwards for de-icing, while the microcapsule phase change heat sink layer utilizes solid-liquid phase change isothermal heat absorption to clamp the temperature of the armor layer and internal components at 70±2℃. This achieves efficient de-icing while completely eliminating accumulated thermal degradation, significantly improving the overall system lifespan.

Description

Technical Field

[0001] This invention relates to the field of special cables and intelligent control technology, specifically to an intelligent de-icing mooring cable and its preparation method. Background Technology

[0002] As the core power supply and communication carrier for aerial ropeways and ground mooring equipment, mooring cables are exposed to strong winds and cold environments for a long time, facing two major technical bottlenecks: First, the traditional circular cross-section has too high wind resistance, which can be reduced by 40% to 60% by optimizing it to an elliptical cross-section; Second, there is the problem of thermal management imbalance during the pulsed thermal de-icing process, which is also the core problem that this invention aims to solve.

[0003] The existing PTC electrothermal layer direct heating de-icing solution has the following main problems: First, it wastes a lot of heat, with more than half of the heat being conducted inward to internal components such as the armor layer and fiber unit, resulting in low energy utilization. Second, repeated pulses cause internal heat to accumulate continuously, and the temperature of internal components continues to rise, which can easily cause the armor steel wire to soften during annealing, the fiber attenuation to increase, and the filler strip to age and become brittle. Third, the thermal protection is not comprehensive, focusing only on the high temperature resistance of the insulation layer and ignoring the thermal protection of the entire system of armor, fiber, and filler strip.

[0004] The combined structure of reflective and heat-absorbing layers has been widely used in building insulation. However, building insulation only passively blocks ambient heat, thus constituting static insulation. Cable pulse de-icing, on the other hand, requires dynamic and active thermal management, necessitating both directional heat utilization and internal component temperature control, making its functional complexity far greater than that of building insulation. Furthermore, the extrusion temperature of cable sheaths reaches 150-170℃, far exceeding the 70℃ melting point of microencapsulated phase change materials, for which current technology lacks a suitable solution.

[0005] Therefore, how to completely prevent the ineffective conduction of heat into the interior and eliminate the thermal degradation of internal components while ensuring the de-icing power and de-icing speed, and at the same time resolve the process contradiction between high-temperature extrusion and the temperature resistance of phase change materials, so as to achieve a balance between efficient de-icing, low-energy operation and long life of the entire system, is a technical problem that needs to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide an intelligent de-icing tethered cable with synergistic protection of a microcapsule phase change heat sink layer and a heat-oriented reflective layer, and a high-temperature resistant insulation layer as thermal safety redundancy, and a method for its preparation. This invention addresses the core contradiction between efficient de-icing and internal thermal protection from three dimensions: structural design, process implementation, and intelligent control.

[0007] The technical solution adopted by this invention to solve its technical problem is: an intelligent de-icing tethered cable, comprising a cable body, a power transmission unit, a distributed sensing fiber optic unit, a segmented controllable electrothermal layer, a microcapsule phase change heat sink layer, and a heat-oriented reflective layer. The power transmission unit is located inside the cable body, the distributed sensing fiber optic unit is arranged along the cable axis inside the cable body, and the segmented controllable electrothermal layer is located on the outer layer of the cable body. The microcapsule phase change heat sink layer is located inside the segmented controllable electrothermal layer, and the heat-oriented reflective layer is located between the microcapsule phase change heat sink layer and the segmented controllable electrothermal layer, with its high reflective surface facing the segmented controllable electrothermal layer. The heat-oriented reflective layer and the microcapsule phase change heat sink layer are stacked sequentially along the radial direction of the cable to form a series thermal resistance structure.

[0008] Furthermore, the heat-directing reflective layer is an aerogel felt composite aluminum foil reflective layer or an aluminized polyimide film, wherein the aluminum foil side faces the segmented controllable electrothermal layer, and the aerogel side or polyimide side faces the microcapsule phase change heat sink layer. The insulation layer of the power transmission unit is made of 150℃-grade high-temperature-resistant cross-linked polyolefin. The microcapsule phase change material of the microcapsule phase change heat sink layer consists of a solid shell encapsulating a phase change core material. The shell material is melamine-formaldehyde resin or silica, and the core material is a paraffin / expanded graphite composite. The phase change material has a melting point of 65~75℃, a latent heat ≥150kJ / kg, a microcapsule particle size of 5~20μm, is filled in a silica matrix, has a filling volume ratio of 40~60%, and a thickness of 1.0~1.5mm.

[0009] Furthermore, the segmented controllable heating layer is a strip-shaped PTC self-regulating polymer, cross-linked by offline electron beam irradiation, with a segment length of 10~50m; adjacent segments are separated by 5~30mm insulation barriers. The cable body also includes a circular double-layer load-bearing armor layer, composed of Z-shaped steel wires wound in a double-reverse spiral, with the steel wire coating being a zinc-5% aluminum or zinc-10% aluminum alloy, the inner layer pitch being 8 times the outer diameter, and the outer layer pitch being 12 times the outer diameter. The cable body also includes an outer sheath, with an elliptical cross-section, a major axis / minor axis ratio of 1.3~1.6, a drag coefficient Cd≤0.8, and identification color stripes on the outer surface.

[0010] Furthermore, a method for manufacturing the cable as described above includes the following steps: preparing a power transmission unit; preparing a distributed sensing fiber optic unit and a communication fiber optic unit; stranding the cable; wrapping a thermally conductive insulating pad; processing a circular double-layer load-bearing armor layer; coating a microcapsule phase change heat sink layer and curing it at low temperature; wrapping a heat-oriented reflective layer with the aluminum foil side facing outwards; preparing and longitudinally wrapping a segmented controllable electrothermal layer; processing a high-strength fiber braided layer; extruding an outer sheath; and applying an anti-icing coating to the surface.

[0011] Furthermore, an intelligent anti-icing control method based on the aforementioned cable is proposed. This method utilizes distributed sensing fiber optic units to acquire real-time temperature and strain distribution along the cable. An edge controller calculates the ice-load strain increment. When the ice-load strain increment exceeds 200 με, the corresponding section's segmented controllable electrothermal layer is activated at a de-icing power of 40~80 W / m, with a single duration ≤20 minutes and an interval ≥2 hours between adjacent de-icing operations. When the lowest temperature along the cable is below +2℃, the anti-icing power is activated at 10~30 W / m. In other operating conditions, a standby power of 5 W / m is maintained. If the distributed sensing fiber optic unit fails or communication is interrupted for more than 30 seconds, the system automatically switches to fail-safe mode, executing a timed de-icing strategy of 40 W / m every 4 hours for 10 minutes, or continuously outputting an anti-icing power of 20 W / m until the sensing fiber optic unit recovers. Simultaneously, a backup temperature control monitor is set up; when the internal temperature of the cable exceeds 90℃, the power supply to the corresponding section is immediately cut off.

[0012] The beneficial effects of this invention are as follows: The heat-oriented reflective layer forcibly reflects the heat radiation generated by the PTC heating layer towards the outer sheath side. Test data shows that under the same de-icing power and environmental conditions, the de-icing time is shortened by about 21% and energy consumption is reduced by 15% to 25% after setting the reflective layer; The microcapsule phase change heat sink layer utilizes the isothermal heat absorption characteristics of solid-liquid phase change to absorb all the residual heat transmitted through the reflective layer. The temperature of internal components such as the armor layer, optical fiber, and filler strip is physically clamped within the range of 70±2℃. Comparative tests show that without the phase change layer, the internal peak temperature can reach 102℃, which will accelerate optical fiber attenuation, armor wire annealing, and filler strip softening during long-term operation. The present invention controls the internal peak temperature at 74℃, which can extend the life of the entire system by more than 50%. After the reflective layer and the phase change layer work together, the internal peak temperature is reduced to 74℃ (95℃ for the reflective layer alone and 89℃ for the phase change layer alone), and the de-icing time is shortened by about 15%. The 150℃ high-temperature resistant insulation layer serves as a third thermal safety redundancy to ensure safe operation under extreme conditions. The distributed sensing fiber monitors the temperature and strain distribution along the line in real time. The edge controller identifies the icing location within 30 seconds and starts the corresponding section of the electric heating layer as needed. When the sensing fiber fails, it automatically switches to the timed de-icing mode to ensure that the system is under control under any operating conditions. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0014] Figure 1 This is a schematic diagram of the cross-sectional structure of the present invention.

[0015] Explanation of reference numerals in the attached figures: 100. Power transmission unit; 110. Distributed sensing fiber optic unit; 120. Communication fiber optic unit; 130. Wrapped thermally conductive insulating pad; 140. Circular double-layer load-bearing armor layer; 150. Microcapsule phase change heat sink layer; 160. Heat-directed reflective layer; 170. Segmented controllable electrothermal layer; 180. High-strength fiber braided layer; 190. Outer sheath; 200. Surface anti-icing coating. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0017] like Figure 1 As shown, the cable of the present invention comprises, from the inside out, a power transmission unit 100, a distributed sensing optical fiber unit 110, a communication optical fiber unit 120, a wrapped thermally conductive insulating pad layer 130, a circular double-layer load-bearing armor layer 140, a microcapsule phase change heat sink layer 150, a heat-oriented reflective layer 160, a segmented controllable electrothermal layer 170, a high-strength fiber braided layer 180, an outer sheath 190, and a surface anti-icing coating 200. The power transmission unit 100 uses three copper or aluminum alloy conductors, with 150°C-grade high-temperature-resistant cross-linked polyolefin insulation extruded onto the conductors, formed by irradiation or dry cross-linking; in extremely cold environments, the copper conductors undergo tin-plating or nickel-plating for corrosion protection. The distributed sensing optical fiber unit 110 uses multimode optical fiber housed in a stainless steel loose tube and injected with water-blocking fiber grease; the communication optical fiber unit 120 uses single-mode optical fiber, also housed in a stainless steel loose tube. Three power transmission units 100 are arranged in a triangular twisted configuration, with sensing and communication optical fibers embedded in the gaps. The gaps are filled with reinforcing strips, and the twisting pitch is controlled at 10 to 15 times the cable core diameter, with a tension error not exceeding 5%. The thermally conductive insulating pad 130 is made of boron nitride-filled polyimide film composite nonwoven fabric with a thickness of 0.2 to 0.5 mm and an overlap rate of not less than 25%.

[0018] The circular double-layer load-bearing armor layer 140 uses Z-shaped steel wire wound in a double-layer reverse spiral. The inner layer pitch is 8 times the outer diameter, and the outer layer pitch is 12 times the outer diameter. The steel wire surface is coated with a zinc-5% aluminum or zinc-10% aluminum alloy. During the armoring process, a pre-tension of approximately 10% to 15% of the breaking force is applied. The entire wire is continuously armored without joints, and the roundness deviation after processing is no more than 0.3 mm.

[0019] The phase change material of the microcapsule phase change heat sink layer 150 is composed of a silica shell encapsulating a paraffin / expanded graphite composite core material. It has a melting point of 70±2℃, a latent heat of not less than 150kJ / kg, and a microcapsule particle size of 5~20μm. The microcapsules are filled into a silica matrix at a volume ratio of 40%~60%, and after vacuum degassing, are uniformly coated onto the outer surface of the armor layer to a thickness of 1.0~1.5mm. After coating, it is cured at room temperature for 24 hours or at 50℃ for 2 hours. The curing temperature should not exceed 80℃ to prevent premature melting of the phase change material.

[0020] The heat-directing reflective layer 160 is made of aerogel felt composite aluminum foil, with an aluminum foil thickness of 0.02 mm and an aerogel layer thickness of 0.78 mm. The aluminum foil side faces outward and the aerogel side faces inward, using a longitudinal wrapping or wrapping method with an overlap rate of not less than 25%. The joints are fixed with thermally conductive tape. This reflective layer has a dual function: during manufacturing, the aerogel side faces inward to isolate the high temperature of the sheath extrusion (150~170℃), ensuring that the temperature of the MEPCM layer does not exceed 65℃; in the working state, the aluminum foil side faces outward to reflect the PTC heat outward for de-icing, with a reflectivity of not less than 95%.

[0021] The segmented controllable electrothermal layer 170 is a strip-shaped PTC self-regulating polymer, extruded and then cross-linked by offline electron beam irradiation with an irradiation dose of 8-12 Mrad. It is cut into 25m segments, with 5-30mm insulating gaps laser-etched between adjacent segments. After the electrodes are led out, they are longitudinally wrapped with constant tension on the outer surface of the reflective layer. The high-strength fiber braided layer 180 is made of UHMWPE, aramid, and carbon fiber in a 50:30:20 ratio, with a braiding density of not less than 90%. It is impregnated with 50℃ low-temperature curing polyurethane and then hot-air cured at 50-60℃. The outer sheath 190 is made of 50℃ resistant TPU, extruded through a shaped die with an elliptical cross section and a major axis / minor axis ratio of 1.3-1.6. It is forced cooled in a 10-15℃ cooling water bath at a linear speed of 3-5m / min, and identification color strips are simultaneously pressed onto the outer surface. The surface anti-icing coating 200 first undergoes plasma pretreatment on the outer sheath, then is sprayed with a fluorosilane-modified SiO2 underlayer and cured at 60°C, followed by a graphene top layer and then cured at 60°C.

[0022] Taking a 1500-meter three-core cable for power supply and communication in a high-altitude cableway as an example: the power unit uses 3×70mm... 2Tin-plated copper conductor with 150℃ grade cross-linked polyolefin insulation, armor layer of 2.5mm+2.5mm Z-shaped steel wire, MEPCM layer with 70℃ melting point and latent heat of 160kJ / kg, silica shell with 50% filler and 1.2mm thickness, 0.8mm aerogel composite aluminum foil reflective layer, PTC polymer 25m segmented, 10Mrad irradiation cross-linking, outer sheath ellipse 38×25mm. Comparative tests were conducted under conditions of -30℃, 20m / s wind speed, and uniform icing of 2-3mm: Example 1 (full structure): de-icing time 15.0min, internal peak temperature 74℃, insulation resistance exceeding 1000MΩ·km after 1000 cycles, fiber optic attenuation less than 0.35dB / km, armor breaking strength retention rate 97.5%, and mass loss rate less than 0.8%; Control Example 1 (no reflective layer, only phase change layer): de-icing time 16.2min, internal peak temperature 95℃; Control Example 2 (no phase change layer, only reflective layer): de-icing time 17.1min, internal peak temperature 89℃; Control Example 3 (no reflective layer and no phase change layer): de-icing time 18.5min, internal peak temperature 102℃, insulation resistance reduced to 850MΩ·km, fiber optic attenuation increased to 0.52dB / km, and armor breaking strength retention rate reduced to 93.0%. The reflective layer contributes to a reduction of approximately 12% in de-icing time (from 17.1 min in Comparative Example 2 to 15.0 min in Example 1); the phase change layer contributes to a reduction of approximately 21°C in internal peak temperature (from 95°C in Comparative Example 1 to 74°C in Example 1); with the two working together, the internal peak temperature decreases from 102°C in Comparative Example 3 to 74°C in Example 1, effectively reducing the cumulative rate of steel wire creep fatigue and significantly extending the overall system life.

Claims

1. An intelligent de-icing mooring cable, characterized in that, The cable includes a cable body, a power transmission unit (100), a distributed sensing fiber optic unit (110), a segmented controllable heating layer (170), a microcapsule phase change heat sink layer (150), and a heat-oriented reflective layer (160). The power transmission unit (100) is located inside the cable body, the distributed sensing fiber optic unit (110) is arranged along the cable axis inside the cable body, and the segmented controllable heating layer (170) is located on the outer layer of the cable body. The microcapsule phase change heat sink layer (150) is located inside the segmented controllable heating layer (170), and the heat-oriented reflective layer (160) is located between the microcapsule phase change heat sink layer (150) and the segmented controllable heating layer (170), with the high reflective surface facing the segmented controllable heating layer (170). The heat-oriented reflective layer (160) and the microcapsule phase change heat sink layer (150) are stacked sequentially along the radial direction of the cable to form a series thermal resistance structure.

2. The intelligent de-icing mooring cable according to claim 1, characterized in that: The heat-oriented reflective layer (160) is an aerogel felt composite aluminum foil reflective layer or an aluminized polyimide film, wherein the aluminum foil side faces the segmented controllable electrothermal layer (170), and the aerogel side or polyimide side faces the microcapsule phase change heat sink layer (150).

3. The intelligent de-icing mooring cable according to claim 1, characterized in that: The insulation layer of the power transmission unit (100) is made of 150℃ high-temperature resistant cross-linked polyolefin.

4. The intelligent de-icing mooring cable according to claim 1, characterized in that: The microcapsule phase change heat sink layer (150) consists of a phase change core material encapsulated by a solid shell material. The shell material is melamine-formaldehyde resin or silicon dioxide, and the core material is a paraffin / expanded graphite composite. The phase change material has a melting point of 65~75℃, a latent heat of ≥150kJ / kg, a microcapsule particle size of 5~20μm, is filled in a silica matrix, has a filling volume ratio of 40~60%, and a thickness of 1.0~1.5mm.

5. The intelligent de-icing mooring cable according to claim 1, characterized in that: The segmented controllable electrothermal layer (170) is a strip-shaped PTC self-limiting polymer that has been cross-linked by offline electron beam irradiation, with a segment length of 10~50m; an insulating partition of 5~30mm is provided between adjacent segments.

6. The intelligent de-icing mooring cable according to claim 1, characterized in that: The cable body also includes a circular double-layer load-bearing armor layer (140), which is composed of Z-shaped steel wires wound in a double reverse spiral. The steel wire coating is zinc 5% aluminum or zinc 10% aluminum alloy. The inner layer pitch is 8 times the outer diameter, and the outer layer pitch is 12 times the outer diameter.

7. The intelligent de-icing tethering cable according to claim 1, characterized in that: The cable body also includes an outer sheath (190), the outer sheath (190) has an elliptical cross-section, a major axis / minor axis ratio of 1.3~1.6, a wind resistance coefficient Cd≤0.8, and an identification color strip on its outer surface.

8. A method for preparing an intelligent de-icing mooring cable as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Prepare a power transmission unit (100); prepare a distributed sensing fiber optic unit (110) and a communication fiber optic unit (120); strand the cable; wrap a thermally conductive insulating pad (130); process a circular double-layer load-bearing armor layer (140); coat a microcapsule phase change heat sink layer (150) and cure it at low temperature; wrap a heat-oriented reflective layer (160) with the aluminum foil side facing out; prepare and longitudinally wrap a segmented controllable electrothermal layer (170); process a high-strength fiber braided layer (180); extrude an outer sheath (190); apply an anti-icing coating to the surface (200).

9. A smart de-icing mooring cable according to any one of claims 1 to 7, characterized in that: The temperature and strain distribution along the cable are acquired in real time by the distributed sensing fiber unit (110); the edge controller calculates the ice load strain increment. When the ice load strain increment exceeds 200με, the segmented controllable electrothermal layer (170) of the corresponding section is activated to the de-icing power of 40~80W / m, the duration of a single operation is ≤20 minutes, and the interval between two adjacent de-icing operations is ≥2 hours; when the lowest temperature along the line is below +2℃, the anti-icing power is activated to 10~30W / m; the standby power of 5W / m is maintained in other operating conditions.

10. The intelligent de-icing mooring cable according to claim 9, characterized in that: When the distributed sensing fiber unit (110) fails or communication is interrupted for more than 30 seconds, it automatically switches to fail-safe mode and executes a timed de-icing strategy of 40W / m every 4 hours for 10 minutes, or continuously outputs anti-icing power of 20W / m until the sensing fiber is restored; at the same time, a backup temperature control monitoring is set up, and when the internal temperature of the cable is detected to exceed 90℃, the power supply of the corresponding section is immediately cut off.

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