Fire hydrant anti-freezing and water leakage monitoring device

Abstract

The invention discloses a fire hydrant anti-freezing and water leakage monitoring device, and relates to the technical field of fire hydrant safety protection. The heat shield sleeve comprises an inner cylinder, a vacuum cavity and an outer cylinder which are sequentially arranged from inside to outside, the vacuum cavity is filled with a honeycomb-shaped heat conduction structure and an aerogel layer, a plurality of microcapsules are evenly embedded in the honeycomb-shaped heat conduction structure, and the microcapsules are filled with phase change materials. The aerogel layer is used for isolating the honeycomb-shaped heat conduction structure from the outer cylinder, and the honeycomb-shaped heat conduction structure is used for storing and releasing heat; a drain hole in the hydrant body penetrates through the inner cylinder and extends into the vacuum cavity; the heat shield sleeve is further provided with a one-way heat conduction unit which is used for guiding external heat into the vacuum cavity in a one-way mode. By the adoption of the scheme, a breathable heat insulation-phase change barrier can be built between frozen soil and the hydrant body, so that a heat bridge is blocked, the temperature of the water escape valve can be kept to be larger than or equal to 2 DEG C in the environment of-35 DEG C, and residual water of the water escape valve is not frozen.

Description

Technical Field

[0001] This invention relates to the field of fire hydrant safety protection technology, specifically to a fire hydrant antifreeze and leakage monitoring device. Background Technology

[0002] In winter, the permafrost layer at high-altitude substations reaches depths of 1.5 to 2 meters, far exceeding the standard burial depth (≤1.2 meters) for fire hydrant drain valves. This causes the valve body to remain embedded in the active permafrost layer for extended periods. Drastic diurnal temperature variations exceeding 30°C trigger repeated freeze-thaw cycles, causing the rubber seals to harden and crack, resulting in persistent micro-leakage. Accumulated water freezes and ruptures the valve body. This micro-leakage accumulates covertly within the permafrost layer, leaving no surface trace and going undetected during routine inspections. Furthermore, residual water after valve closure cannot be drained due to valve malfunctions; the stagnant water freezes and expands, ultimately leading to the bursting or deformation of the valve body or seat.

[0003] Current protective measures have fundamental flaws: the insulation layer of wet systems fails at -35℃, and conventional insulation only wraps the plug body, failing to isolate the thermal bridge between the plug body and the permafrost. Furthermore, replacing the antifreeze plug body requires cutting off the water supply and removing the plug body, resulting in high modification costs; mains power tracing is affected by high-altitude power grid failures, making continuous heating impossible, and the need to lay cables is costly and carries a high risk of power outages; manual maintenance is difficult due to the hardness of the permafrost and poor accessibility in winter, making it difficult to clean clogged drain valves; deep burial modifications result in soaring costs due to dynamic changes in permafrost depth and damage to permafrost stability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a fire hydrant antifreeze and leakage monitoring device. This solution can establish a breathable thermal insulation-phase change barrier between the frozen soil and the hydrant body, thereby blocking thermal bridges and maintaining the drain valve temperature at ≥2℃ in an environment of -35℃, preventing the residual water in the drain valve from freezing.

[0005] This invention is achieved through the following technical solution: A fire hydrant antifreeze and leakage monitoring device includes: A thermal shield sleeve is used to partially cover a plug located below ground level, and the drain valve on the plug is located within the coverage area; The heat shield sleeve includes an inner cylinder, a vacuum chamber, and an outer cylinder arranged sequentially from the inside to the outside. The vacuum chamber is filled with a honeycomb thermally conductive structure and an aerogel layer. A plurality of microcapsules are uniformly embedded in the honeycomb thermally conductive structure, and the microcapsules are filled with a phase change material. The aerogel layer is used to isolate the honeycomb thermally conductive structure from the outer cylinder. The honeycomb thermally conductive structure is used to store and release heat. The drain hole on the plug body passes through the inner cylinder and extends into the vacuum chamber. The heat shield sleeve is also equipped with a unidirectional heat conduction unit, which is used to guide external heat into the vacuum cavity in one direction.

[0006] Compared to existing technologies, where the insulation layer of wet systems fails at -35℃ and conventional insulation only wraps the hydrant body without isolating the thermal bridge between the hydrant body and the frozen soil, and the residual water cannot be drained after the drain valve is closed due to valve malfunction, the stagnant water freezes and expands, eventually leading to the bursting or deformation of the hydrant body or valve seat, this invention provides a fire hydrant antifreeze and leakage monitoring device. Using this solution, a breathable thermal insulation-phase change barrier can be established between the frozen soil and the hydrant body, thereby blocking the thermal bridge and maintaining the drain valve temperature at ≥2℃ in an environment of -35℃, preventing the residual water in the drain valve from freezing. The specific design includes a heat shield sleeve fitted onto the hydrant body. The heat shield sleeve is located below ground level, with its top edge 0-10cm below ground level and its bottom extending at least 0.3m below the frost layer. At this depth, the underground hydrant body is partially enclosed within the heat shield sleeve. The lower end of the heat shield sleeve extends to the bottom of the drain valve, thus completely enclosing the drain valve and forming an annular insulation cavity. This ensures that the drain hole is located within the vacuum-phase change insulation zone of the heat shield. Specifically, the heat shield sleeve comprises an inner cylinder and an outer cylinder arranged sequentially from the outside. The inner cylinder is tightly fitted against the original outer wall of the fire hydrant, while the diameter of the outer cylinder is ≥ the maximum frost heave envelope of the frost-covered soil + 20cm. A vacuum cavity is left between the inner and outer cylinders to form an annular chamber. This vacuum cavity is filled with a honeycomb-shaped thermally conductive structure and an aerogel layer. The aerogel layer is arranged circumferentially on the inner side of the outer cylinder and has an extremely low thermal conductivity (λ≤0.016W·m). -1 ·K -1 The material is fiber-reinforced SiO2 aerogel. The honeycomb thermally conductive structure can be made of any thermally conductive material. It is honeycomb-shaped and contains several microcapsules evenly distributed within it. Temperature storage and release are achieved through an internal phase change material. A unidirectional thermally conductive unit transfers heat from the permafrost layer to the vacuum chamber in one direction only, with the reverse flow blocked to prevent heat loss from the plug at night. When high daytime heat is introduced into the vacuum chamber, the internal temperature rises, maintaining the drain hole at a corresponding temperature. Furthermore, the honeycomb thermally conductive structure stores heat and releases it at certain temperatures, thus maintaining the drain hole temperature for an extended period. This ensures the drain valve temperature remains ≥2℃, preventing freezing and blockage. Additionally, a thermally conductive insulating sleeve is installed inside the inner cylinder to prevent heat loss from the plug. In the above solution, the combination of unidirectional heat conduction unit, honeycomb heat conduction structure and aerogel layer can block thermal bridges and maintain the temperature of the drain valve at ≥2℃ in an environment of -35℃, so that the residual water in the drain valve does not freeze.

[0007] To further optimize the microcapsule's heat storage capacity, the honeycomb thermally conductive structure is embedded within the aerogel layer.

[0008] Further optimization involves using a tetradecane / expanded graphite composite as the phase change material. Specifically, 3D-printed honeycomb-phase change microcapsules can be directly embedded within the aerogel layer and distributed in an array. The phase change material in these microcapsules is a tetradecane / expanded graphite composite (phase change point 5°C, latent heat 220 kJ·kg⁻¹). -1 ).

[0009] To further optimize the process, in order to absorb solar radiation and store heat during the day and release latent heat at night to maintain the bottom of the plug at ≥2°C, the surface of the microcapsule is sputtered with a selective absorption coating.

[0010] Further optimized, as a specific structure of a unidirectional heat conduction unit, the unidirectional heat conduction unit includes several copper-water gravity heat pipes, which are evenly distributed circumferentially along the heat shield sleeve. One end of each copper-water gravity heat pipe extends into the permafrost layer, and the other end passes through the outer cylinder and extends into the vacuum chamber. A one-way valve is installed inside each copper-water gravity heat pipe. In this scheme, the unidirectional heat conduction unit adopts a passive thermal diode, which is a heat pipe-thermal diode structure implanted at the bottom of the vacuum chamber, i.e., a copper-water gravity heat pipe + one-way valve structure, which is evenly distributed circumferentially along the heat shield cylinder, with one end extending into the permafrost layer and the other end extending into the vacuum chamber. In the copper-water gravity heat pipe, copper serves as the outer shell material of the heat pipe, and due to its excellent thermal conductivity, it can quickly absorb and transfer heat. Water serves as the working fluid, efficiently transferring heat energy through the phase change process of evaporation and condensation. Gravity heat pipes utilize gravity and capillary action to allow the working fluid to flow freely within the heat pipe, requiring almost no additional pumping power. A one-way valve is installed in the condensation section of the heat pipe to control the flow direction of the working fluid inside, ensuring efficient heat transfer while preventing unnecessary backflow of condensate or other fluids. It possesses a degree of elasticity and guiding function and is typically made of polymer or metal materials to ensure high-temperature resistance and corrosion resistance.

[0011] To further optimize the detection of leakage caused by the failure of the valve disc or drain valve seal, a Y-type micro-permeation diverter is also included. The Y-type micro-permeation diverter includes a Y-type copper pipe that communicates with the drain hole. The two outlets of the Y-type copper pipe are respectively connected to the large-diameter main pipe and the small-diameter branch pipe. The large-diameter main pipe extends downward through the heat shield sleeve and into the gravel layer. The outlet of the small-diameter branch pipe is connected to a hydrophilic cotton rope, which extends upward through the heat shield sleeve and connects to the water mirror pad. The water mirror pad is fitted onto the plug body and located between the plug body flange and the ground. The water mirror pad contains a humidity sensing unit. In this design, the drain hole faces downward and connects to a Y-type micro-permeation diverter, i.e., a Y-type copper pipe. The main pipe has a diameter of φ10mm and passes through the bottom of the heat shield to drain directly into the gravel layer. The outer wall is covered with a 10mm aerogel sleeve, which is responsible for large-flow drainage when the drain valve is opened. The small-diameter branch pipe has a diameter of φ1.5mm, and its inlet is 5mm lower than the main pipe. The outlet is siphoned to the water mirror pad via the hydrophilic cotton rope, forming a "micro-permeation siphon channel" to detect leakage caused by the failure of the valve disc or drain valve seal.

[0012] To further optimize the process and achieve micro-permeability siphoning, the inlet of the small-diameter branch pipe is lower than the inlet of the large-diameter main pipe. The small-diameter branch pipe is a siphon pipe with a downward bend from the inlet to the outlet. Because its inlet is lower than the inlet of the large-diameter main pipe, during normal drainage, the large-diameter main pipe submerges the small-diameter branch pipe, creating a liquid seal and siphoning the middle section. When micro-permeability (<0.2mL) occurs, the liquid level is low, and the level difference ensures that only the micro-permeability is siphoned.

[0013] To further optimize the formation of a multi-sensor coupling pad and to report micro-permeation water data, the water mirror pad includes a sensing pad layer, a composite layer, and a protective layer arranged sequentially from bottom to top. The sensing pad adopts a capacitive grid structure composed of polyimide and graphene, and polymer optical fiber microbending sensing fibers are embedded in the sensing pad. The composite layer includes a vertically contactable, separable friction layer and a piezoelectric film integrated on the back of the sensing pad layer; A capacitive humidity chip is also attached to the back of the sensing pad. In this design, the bottom layer is the sensing pad, which is a 0.8mm thick, 40mm wide polyimide-graphene capacitive grid laid at the junction of the bolt flange and the ground. Polyimide (PI) serves as the substrate to prevent cutting, such as from gravel, and is temperature resistant from -60℃ to +200℃. The graphene capacitive grid can detect changes in the dielectric constant of the water film within 0–2mm of the pad surface, detecting leakage water at a resolution of 0.05mL. Polymer optical fiber micro-bending sensing fibers are implanted in parallel on the sensing pad. The weight of the leakage water film or the expansion of ice crystals causes micro-bending losses, forming a complementary dual-mode signal. A vertically contactable, separable triboelectric layer (PTFE / Al) and a PVDF piezoelectric film are integrated on the back of the sensing pad. The PVDF piezoelectric film also functions as a micro-vibration pickup. A nickel-chromium-constantan thin-film thermocouple is located on the back of the PVDF piezoelectric layer for temperature measurement with an accuracy of ±0.1℃, used for ice-water phase transition temperature jump detection and ambient temperature detection. Simultaneously, a MEMS capacitive humidity chip with an accuracy of ±2%RH is attached to the back of the sensing pad for ambient humidity detection. Through the vertically contactable, separable triboelectric layer (PTFE / Al) and the PVDF piezoelectric film, a triboelectric-piezoelectric hybrid nanogenerator (T-PENG) is formed. Utilizing high-altitude strong winds, raindrops, freeze-thaw cycles, seepage, and diurnal temperature variations, it generates 50-200μW of instantaneous power. The generated pulsed electrical energy is stored in a 0.1F supercapacitor (or a 3mAh solid-state thin-film battery) to drive a BLE low-power wireless module (the ground then forwards the BLE low-power wireless module data to the monitoring platform via a wireless edge gateway), enabling "micro-seepage event-triggered" data reporting. This requires no mains power and has a continuous power supply. The top protective layer uses a fluorocarbon coating, which is in direct contact with the ground layer. The 0.05-0.1mm fluorocarbon coating is UV resistant, snow and ice resistant, hydrophobic, and wear resistant. The above-mentioned sensing pad, polymer fiber micro-bent sensing fiber, composite layer, and protective layer form a "water mirror" non-invasive leakage sensing pad, namely an ultra-thin flexible capacitor-fiber-multi-sensor coupling pad. The TinyML model is embedded in the edge MCU, which uses environmental temperature, humidity, and vibration as features to dynamically filter out false alarms from rain, snow, vehicle running, and condensation, improving the accuracy of leakage identification and thus achieving accurate "micro-leakage event triggered" data reporting.

[0014] To further optimize the design and absorb frost heave displacement, thus preventing stress transmission that could affect the structure inside the outer cylinder, a compressible corrugated section is provided on the inner wall of the outer cylinder. This compressible corrugated section itself is capable of deformation, and is made of materials such as sponge or corrugated stainless steel, to buffer external forces.

[0015] To further optimize the design and buffer frost heave, an anti-frost heave ring is included, which is located on the outside of the outer cylinder. The anti-frost heave ring comprises a closed-cell foam board in the inner layer and crushed stone in the outer layer. In this design, the inner diameter of the anti-frost heave ring is close to the outer cylinder of the thermal shield cylinder, and its ring width is 200mm. The inner layer is a 50mm thick closed-cell EPS foam board. The outer layer is 150mm of graded crushed stone with a compaction degree of ≥90%. Its top surface is flush with the ground, and its bottom surface extends ≥0.3m below the frost line, serving as both a drainage channel and a frost heave buffer.

[0016] As a redundancy solution, the thermal shield cylinder can be locked to the bolt body via a split clamp, and only two anti-loosening bolts need to be loosened to wrap around the existing bolt body; the water mirror gasket is a C-shaped ring gasket with Velcro overlap (no bolts), which can be independently disassembled and installed. The entire device is IP66, with a service life of ≥15 years, and can withstand 1000 cycles of -45℃ to +70℃.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention provides a fire hydrant antifreeze and leakage monitoring device, which uses a heat shield sleeve and an inner cylinder in the heat shield sleeve to wrap the drain valve → vacuum-phase change-aerogel-corrugated section-foam crushed stone in one step to establish a breathable heat insulation-phase change barrier between the frozen soil and the hydrant body, thereby blocking the thermal bridge and placing the drain hole in a constant temperature zone of ≥2℃, so that the residual water in the drain valve does not freeze.

[0018] 2. The present invention provides a fire hydrant antifreeze and leakage monitoring device with a dual-channel micro-seepage siphon-drainage system: a single-hole Y-shaped copper pipe, a large-diameter main pipe of φ10mm for large water drainage, and a small-diameter branch pipe of φ1.5mm + hydrophilic cotton rope for siphon micro-seepage ≤0.2mL; the liquid level difference achieves "zero accidental aspiration".

[0019] 3. The present invention provides a fire hydrant antifreeze and water leakage monitoring device, which uses a three-mode self-powered sensing pad: a capacitive grid + fiber micro-bending + triboelectric T-PENG, all three of which share the same pad surface and can drive BLE without an external power source.

[0020] 4. The present invention provides a fire hydrant antifreeze and leakage monitoring device, TinyML ice-water phase change-freeze-thaw micro-vibration algorithm: real-time threshold of temperature-humidity-vibration triaxial features, filtering out rainwater / vehicle crushing, and high leakage identification.

[0021] 5. The present invention provides a fire hydrant antifreeze and leakage monitoring device with a frost heave-absorbing corrugated outer cylinder: corrugated stainless steel + EPS crushed stone ring, which can absorb ±20mm frost heave displacement while maintaining IP66.

[0022] 6. The present invention provides a fire hydrant antifreeze and leakage monitoring device, which can be installed modularly without tools: the heat shield is locked with a split clamp; the water mirror pad is connected with Velcro; it can be completed quickly without disassembling the hydrant body, without interrupting water supply or power. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 An overall isometric view of the fire hydrant antifreeze and leakage monitoring device provided by the present invention; Figure 2 Cross-sectional view of the fire hydrant antifreeze and leakage monitoring device provided by the present invention; Figure 3 A layered exploded view of the water mirror pad provided by the present invention; Figure 4 The flowchart of T-PENG energy harvesting and wireless transmission provided by the present invention.

[0024] The attached diagram shows the markings and corresponding component names: 1-Heat shield sleeve, 101-Inner cylinder, 102-Vacuum cavity, 103-Honeycomb thermal conductive structure, 104-Aerogel layer, 105-Outer cylinder, 106-One-way thermal conductive unit, 1061-Copper-water gravity heat pipe, 2-Large diameter main pipe, 3-Small diameter branch pipe, 4-Hydrophilic cotton rope, 5-Water mirror pad, 501-Sensing pad layer, 502-Polymer optical fiber micro-bent sensing fiber, 503-Composite layer, 504-Protective layer, 6-Frozen soil layer, 7-Gravel layer, 8-Anti-freeze heave ring, 9-Plug body, 10-Thermal conductive isolation sleeve. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0026] Example 1: This Example 1 provides a fire hydrant antifreeze and leakage monitoring device, such as... Figure 1 and Figure 2 As shown, it includes: A heat shield sleeve 1 is used to partially cover a plug body 9 located below the ground, and the drain valve on the plug body 9 is located within the coverage area. The heat shield sleeve 1 includes an inner cylinder 101, a vacuum chamber 102, and an outer cylinder 105 arranged sequentially from the inside to the outside. The vacuum chamber 102 is filled with a honeycomb thermally conductive structure 103 and an aerogel layer 104. A plurality of microcapsules are uniformly embedded in the honeycomb thermally conductive structure 103, and the microcapsules are filled with a phase change material. The aerogel layer 104 is used to isolate the honeycomb thermally conductive structure 103 and the outer cylinder 105. The honeycomb thermally conductive structure 103 is used to store and release heat. The drain hole on the plug 9 passes through the inner cylinder 101 and extends into the vacuum chamber 102. The heat shield sleeve 1 is also provided with a unidirectional heat conduction unit 106, which is used to guide external heat into the vacuum chamber 102 in one direction.

[0027] Compared to existing technologies, where the insulation layer of wet systems fails at -35℃ and conventional insulation only wraps the hydrant body 9 without isolating the thermal bridge between the hydrant body 9 and the frozen soil, and the residual water cannot be drained after the drain valve is closed due to valve malfunction, the stagnant water freezes and expands, eventually causing the hydrant body 9 or valve seat to burst or deform and be damaged, this invention provides a fire hydrant antifreeze and leakage monitoring device. Using this solution, a breathable thermal insulation-phase change barrier can be established between the frozen soil and the hydrant body 9, thereby blocking the thermal bridge and maintaining the drain valve temperature at ≥2℃ in an environment of -35℃, so that the residual water in the drain valve does not freeze. The specific scheme includes a heat shield sleeve 1 fitted onto the plug body 9. The heat shield sleeve 1 is located below the ground, with its top edge 0-10cm below the ground and its bottom extending ≥0.3m below the frozen soil layer 6. At this time, the underground plug body 9 is partially enclosed. The lower end of the heat shield sleeve 1 extends to the bottom of the drain valve, thereby completely enclosing the drain valve to form an annular insulation cavity and ensuring that the drain hole is located in the heat shield vacuum-phase change insulation zone. Specifically, the heat shield sleeve 1 includes an inner cylinder 101 and an outer cylinder 105 arranged sequentially from the inside out. The inner cylinder 101 is tightly attached to the outer wall of the original fire hydrant, while the diameter of the outer cylinder 105 is ≥ the maximum frost heave envelope of the frozen soil + 20cm. A vacuum cavity 102 is left between the inner cylinder 101 and the outer cylinder 105 to form an annular chamber. The vacuum cavity 102 is filled with a honeycomb thermally conductive structure 103 and an aerogel layer 104. The aerogel layer 104 is arranged circumferentially inside the outer cylinder 105 and has an extremely low thermal conductivity (λ≤0.016W·m). -1 ·K -1The structure is made of fiber-reinforced SiO2 aerogel. The honeycomb thermally conductive structure 103 can be made of any thermally conductive material. It is honeycomb-shaped and contains several microcapsules evenly distributed within it. Temperature storage and release are achieved through internal phase change materials. A unidirectional thermally conductive unit 106 transfers heat from the frozen soil layer 6 to the vacuum chamber 102 in one direction only, with the reverse flow blocked to prevent heat loss from the plug 9 at night. When the high heat from the outside during the day is introduced into the vacuum chamber 102, the internal temperature of the vacuum chamber 102 rises, maintaining the corresponding temperature of the drain hole. Furthermore, the honeycomb thermally conductive structure 103 can store heat and release heat at certain temperatures, thus maintaining the temperature of the drain hole for a long time. This ensures that the drain valve temperature remains ≥2℃, preventing freezing and blockage. Additionally, a thermally conductive insulating sleeve 10 is provided inside the inner cylinder 101 to prevent heat loss from the plug. In the above solution, the combination of the unidirectional heat conduction unit 106, the honeycomb heat conduction structure 103 and the aerogel layer 104 can block thermal bridges and maintain the temperature of the drain valve at ≥2℃ in an environment of -35℃, so that the residual water in the drain valve does not freeze.

[0028] In this embodiment, to further ensure the heat storage capacity of the microcapsules, the honeycomb thermally conductive structure 103 is embedded in the aerogel layer 104.

[0029] In this embodiment, the phase change material is a tetradecane / expanded graphite composite. Specifically, 3D-printed "honeycomb-phase change" microcapsules can be directly embedded within the aerogel layer 104 and distributed in an array. The phase change material in these microcapsules is a tetradecane / expanded graphite composite (phase change point 5°C, latent heat 220 kJ·kg⁻¹). -1 ).

[0030] In this embodiment, in order to absorb solar radiation and store heat during the day and release latent heat at night to maintain the bottom of the plug 9 at ≥2°C, the surface of the microcapsule is sputtered with a selective absorption coating.

[0031] In this embodiment, as a specific structure of a one-way heat conduction unit 106, the one-way heat conduction unit 106 includes a plurality of copper-water gravity heat pipes 1061, which are evenly distributed circumferentially along the heat shield sleeve 1; one end of the copper-water gravity heat pipe 1061 extends into the frozen soil layer 6, and the other end passes through the outer cylinder 105 and extends into the vacuum chamber 102; a one-way valve plate is provided inside the copper-water gravity heat pipe 1061. In this design, the unidirectional heat conduction unit 106 employs a passive thermal diode. This passive thermal diode is a heat pipe-thermal diode structure implanted at the bottom of the vacuum chamber 102, specifically a copper-water gravity heat pipe 1061 with a one-way valve. It is evenly distributed circumferentially along the heat shield cylinder, with one end extending into the permafrost layer 6 and the other end into the vacuum chamber 102. In the copper-water gravity heat pipe 1061, copper serves as the outer shell material, and its excellent thermal conductivity allows for rapid heat absorption and transfer. Water, as the working fluid, efficiently transfers heat energy through the phase change process of evaporation and condensation. The gravity heat pipe utilizes gravity and capillary action to allow the working fluid to flow freely within the heat pipe, requiring almost no additional pumping power. The one-way valve is installed on the condensation section of the heat pipe to control the flow direction of the working fluid inside, ensuring efficient heat transfer while preventing unnecessary backflow of condensate or other fluids. It possesses a certain degree of elasticity and guiding function and is typically made of polymer or metal materials to ensure high-temperature resistance and corrosion resistance.

[0032] In this embodiment, in order to detect leakage caused by the failure of the valve disc or the drain valve to seal, a Y-type micro-permeation diverter is also included. The Y-type micro-permeation diverter includes a Y-type copper pipe that communicates with the drain hole. The two outlets of the Y-type copper pipe are respectively connected to the large-diameter main pipe 2 and the small-diameter branch pipe 3. The large-diameter main pipe 2 extends downward through the heat shield sleeve 1 and into the gravel layer 7. The outlet of the small-diameter branch pipe 3 is connected to a hydrophilic cotton rope 4. The hydrophilic cotton rope 4 extends upward through the heat shield sleeve 1 and connects to the water mirror pad 5. The water mirror pad 5 is fitted onto the plug body 9 and is located between the flange of the plug body 9 and the ground. The water mirror pad 5 contains a humidity sensing unit. In this scheme, the drain hole faces downward and is connected to a Y-type micro-permeation diverter, i.e., a Y-type copper pipe. The main pipe has a diameter of 2φ10mm and passes through the bottom of the heat shield to reach the gravel layer 7 for drainage. The outer wall is covered with a 10mm aerogel sleeve, which is responsible for large-flow drainage when the drain valve is opened. The small-diameter branch pipe 3 has a diameter of 1.5mm, and its inlet is 25mm lower than the main pipe. The outlet is siphoned to the water mirror pad 5 through the hydrophilic cotton rope 4, forming a "micro-permeation siphon channel" to detect leakage caused by the failure of the valve disc or drain valve seal.

[0033] In this embodiment, to achieve micro-percolation siphoning, the inlet of the small-diameter branch pipe 3 is lower than the inlet of the large-diameter main pipe 2. The small-diameter branch pipe 3 is a siphon pipe, with a downward bend from the inlet to the outlet. Since the inlet of the small-diameter branch pipe 3 is lower than the inlet of the large-diameter main pipe 2, during normal drainage, the large-diameter main pipe 2 submerges the small-diameter branch pipe 3, causing it to be liquid-sealed and siphoning the middle section. When micro-percolation (<0.2mL) occurs, the liquid level is low, and the liquid level difference ensures that only the micro-percolation is siphoned.

[0034] Example 2: This Example 2 further optimizes Example 1 by providing a multi-sensor coupling pad for reporting micro-infiltration data, such as... Figure 3 and Figure 4 As shown.

[0035] The water mirror pad 5 includes a sensing pad layer 501, a composite layer 503 and a protective layer 504 arranged sequentially from bottom to top; The sensing pad 501 adopts a capacitor grid structure composed of polyimide and graphene, and polymer optical fiber microbending sensing fiber 502 is embedded in the sensing pad 501. The composite layer 503 includes a vertically contactable, separable friction layer and a piezoelectric film integrated on the back side of the sensing pad layer 501. A capacitive humidity chip is also attached to the back of the sensing pad 501. In this design, the bottom layer is the sensing pad 501, which is a 0.8mm thick, 40mm wide polyimide-graphene capacitive grid laid at the junction of the flange of the bolt 9 and the ground. Polyimide (PI) serves as the substrate to prevent cutting, such as from gravel, and is temperature resistant from -60℃ to +200℃. The graphene capacitive grid can detect the change in dielectric constant of the water film within 0–2mm on the pad surface, detecting leakage water at a resolution of 0.05mL. Polymer optical fiber micro-bending sensing fibers 502 are implanted in parallel on the sensing pad 501. The weight of the leakage water film or the expansion of ice crystals causes micro-bending loss, forming a complementary dual-mode signal. On the back of the sensing pad 501, a vertical contact separable friction layer (PTFE / Al) and a PVDF piezoelectric film are integrated. The PVDF piezoelectric film also serves as a micro-vibration pickup. On the back of the PVDF piezoelectric layer, there is a nickel-chromium-constantan thin film thermocouple for measuring temperature with an accuracy of ±0.1℃, used for ice-water phase change temperature jump detection and ambient temperature detection. At the same time, a MEMS capacitive humidity chip with an accuracy of ±2%RH is attached to the back of the sensing pad for ambient humidity detection. A triboelectric-piezoelectric hybrid nanogenerator (T-PENG) is formed by combining a vertically contacting, separable triboelectric layer (PTFE / Al) with a PVDF piezoelectric film. Utilizing high-altitude strong winds, raindrops, freeze-thaw cycles, seepage, and diurnal temperature variations, it generates 50-200 μW of instantaneous power. This pulsed energy is stored in a 0.1F supercapacitor (or a 3mAh solid-state thin-film battery) to drive a BLE low-power wireless module (the ground-based system then forwards the BLE low-power wireless module data to the monitoring platform via a wireless edge gateway). This enables "micro-seepage event-triggered" data reporting, requiring no mains power and providing continuous power. The top protective layer, made of 504 stainless steel with a fluorocarbon coating, is in direct contact with the ground. This 0.05-0.1mm fluorocarbon coating is UV resistant, snow and ice resistant, hydrophobic, and wear-resistant. The "water mirror" non-invasive leakage sensing pad, consisting of the aforementioned sensing pad 501, polymer optical fiber micro-bending sensing fiber 502, composite layer 503, and protective layer 504, is an ultra-thin flexible capacitor-optical fiber-multi-sensor coupling pad. The TinyML model is embedded in the edge MCU, using ambient temperature, humidity, and vibration as characteristics to dynamically filter out false alarms from rain, snow, vehicle running over, and condensation, thereby improving the accuracy of leakage identification and achieving accurate "micro-seepage event triggered" data reporting.

[0036] In this embodiment, to absorb frost heave displacement and avoid stress transmission that could affect the structure inside the outer cylinder 105, a compressible corrugated section is provided on the inner wall of the outer cylinder 105. This compressible corrugated section itself is capable of deformation, and is made of materials such as sponge or corrugated stainless steel, to buffer external forces.

[0037] In this embodiment, a frost heave buffering ring 8 is also included, which is disposed on the outside of the outer cylinder 105. The frost heave ring 8 includes a closed-cell foam board in the inner layer and crushed stone in the outer layer. In this design, the inner diameter of the frost heave ring 8 is close to the outer cylinder 105 of the thermal shield cylinder, and its ring width is 200mm; the inner layer is a 50mm thick closed-cell EPS foam board; the outer layer is 150mm graded crushed stone of 20-40mm, with a compaction degree ≥90%; its top surface is flush with the ground, and its bottom surface extends ≥0.3m below the frost line, serving as both a drainage channel and a frost heave buffer.

[0038] In this embodiment, the heat shield cylinder can be locked onto the bolt body 9 by a split clamp, and only two anti-loosening bolts need to be loosened to wrap around the existing bolt body 9; the water mirror pad 5 is a C-shaped ring pad with Velcro overlap (no bolts), which can be independently disassembled and installed. The entire device is IP66, with a service life of ≥15 years, and can withstand 1000 cycles of -45℃ to +70℃.

[0039] The actual operation steps of this plan are as follows: For an outdoor fire hydrant of DN100 in a 110kV substation, with a frozen soil layer of 6 meters and a depth of 1.8m, and a winter extreme temperature of -38℃.

[0040] 1. Excavation of frozen soil: With the fire hydrant as the center, excavate a columnar pit with a diameter of 0.6m and a depth of (frozen soil depth + 0.3m) (e.g., frozen soil 1.8m → excavation 2.3m).

[0041] 2. Subsequently, the heat shield cylinder is fixed around the hydrant body 9 using segmented clamps, and installed upwards from 0.3m below the frost line to 0.1m below the flange. A Y-type micro-permeability diverter is installed simultaneously, and finally, the clamps are tightened. The heat shield cylinder comprises an inner cylinder 101 and an outer cylinder 105 arranged sequentially from the inside out. The inner cylinder 101 is tightly attached to the original outer wall of the fire hydrant, while the diameter of the outer cylinder 105 is ≥ the maximum frost heave envelope of the frost line + 20cm. A vacuum cavity 102 is left between the inner cylinder 101 and the outer cylinder 105 to form an annular chamber. The vacuum cavity 102 is filled with a honeycomb-shaped thermally conductive structure 103 and an aerogel layer 104. The aerogel layer 104 is circumferentially arranged inside the outer cylinder 105 and has an extremely low thermal conductivity (λ≤0.016W·m). -1 ·K -1The fiber-reinforced SiO2 aerogel 103. The honeycomb thermally conductive structure 103 can be made of any thermally conductive material. It is honeycomb-shaped and contains several microcapsules. The microcapsules are evenly distributed and the temperature is stored and released through the internal phase change material. The unidirectional heat conduction unit 106 adopts a passive thermal diode, which is a heat pipe-thermal diode structure implanted at the bottom of the vacuum chamber 102, namely a copper-water gravity heat pipe + one-way valve plate. It is evenly distributed around the heat shield cylinder, with one end extending into the frozen soil layer 6 and the other end extending into the vacuum chamber 102. It is used to transfer heat from the frozen soil layer 6 to the vacuum chamber 102 in one direction, and the heat will only flow in one direction and be blocked in the opposite direction to prevent heat loss from the plug 9 at night. When the high heat from the outside during the day is introduced into the vacuum chamber 102, the internal temperature of the vacuum chamber 102 will rise, so that the drain hole can maintain the corresponding temperature. Secondly, the honeycomb heat conduction structure 103 can store heat and release heat at a certain temperature. In this way, the temperature of the drain hole can be maintained for a long time, thereby ensuring that the temperature of the drain valve is always ≥2℃ and preventing freezing and blockage. In the above solution, the combination of the unidirectional heat conduction unit 106, the honeycomb heat conduction structure 103 and the aerogel layer 104 can block thermal bridges and maintain the temperature of the drain valve at ≥2℃ in an environment of -35℃, so that the residual water in the drain valve does not freeze.

[0042] The drain hole faces downwards and connects to a Y-type micro-permeation diverter, i.e., a Y-type copper pipe. The main pipe has a diameter of 2φ10mm and passes through the bottom of the heat shield to reach the gravel layer 7 for drainage. The outer wall is covered with a 10mm aerogel sleeve, which is responsible for large-flow drainage when the drain valve is opened. The small-diameter branch pipe has a diameter of 3φ1.5mm, and its inlet is 25mm lower than the main pipe. The outlet is siphoned to the water mirror pad 5 through the hydrophilic cotton rope 4, forming a "micro-permeation siphon channel" to detect leakage caused by the failure of the valve disc or drain valve seal.

[0043] 3. Then install the anti-frost heave ring 8 and backfill with crushed stone.

[0044] 4. Wrap the water mirror pad 5 around the flange root and install it on the bottom surface, overlapping it with Velcro. The water mirror pad 5 includes a bottom layer of sensing pad 501, which is a 0.8mm thick, 40mm wide polyimide-graphene capacitive mesh, laid at the junction of the bolt body 9 flange and the ground; the polyimide (PI) base is used to prevent cutting, such as gravel, and is temperature resistant from -60℃ to +200℃. The graphene capacitive mesh can detect the change in dielectric constant of the water film within 0–2mm on the pad surface, detecting leakage water at a resolution of 0.05mL.

[0045] Polymer optical fiber microbending sensing fiber 502 is implanted in parallel on the sensing pad 501. The microbending loss caused by the weight of the leaking water film or the expansion of ice crystals forms a complementary dual-mode signal.

[0046] On the back of the sensing pad 501, a vertical contact separable friction layer (PTFE / Al) and a PVDF piezoelectric film are integrated. The PVDF piezoelectric film also serves as a micro-vibration pickup. On the back of the PVDF piezoelectric layer, there is a nickel-chromium-constantan thin film thermocouple for measuring temperature with an accuracy of ±0.1℃, used for ice-water phase change temperature jump detection and ambient temperature detection. At the same time, a MEMS capacitive humidity chip with an accuracy of ±2%RH is attached to the back of the sensing pad for ambient humidity detection. By using a vertically contactable, separable triboelectric layer (PTFE / Al) and a PVDF piezoelectric film to form a triboelectric-piezoelectric hybrid nanogenerator (T-PENG), a 50-200 μW instantaneous power is generated by utilizing strong winds, raindrops, freeze-thaw cycles, seepage, and micro-vibrations caused by diurnal temperature variations at high altitudes. The generated pulsed electrical energy is stored in a 0.1F supercapacitor (or a 3mAh solid-state thin-film battery) to drive a BLE low-power wireless module (the ground then forwards the BLE low-power wireless module data to the monitoring platform via a wireless edge gateway), enabling "micro-seepage event-triggered" data reporting. This requires no mains power and has a continuous power supply.

[0047] The top protective layer, 504, is made of fluorocarbon coating. It is in direct contact with the ground layer and has a 0.05-0.1mm fluorocarbon coating that is UV resistant, snow and ice resistant, hydrophobic, and wear resistant.

[0048] The "water mirror" non-invasive leakage sensing pad, consisting of the aforementioned sensing pad 501, polymer optical fiber micro-bending sensing fiber 502, composite layer 503, and protective layer 504, is an ultra-thin flexible capacitor-optical fiber-multi-sensor coupling pad. The TinyML model is embedded in the edge MCU, using ambient temperature, humidity, and vibration as characteristics to dynamically filter out false alarms from rain, snow, vehicle running over, and condensation, thereby improving the accuracy of leakage identification and achieving accurate "micro-seepage event triggered" data reporting.

[0049] 5. Finally, activate the BLE tag through the mobile app to complete the threshold learning.

[0050] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fire hydrant antifreeze and leakage monitoring device, characterized in that, include: A heat shield sleeve (1) is used to partially cover a plug (9) located below ground level, and the drain valve on the plug (9) is located within the coverage area; The heat shield sleeve (1) includes an inner cylinder (101), a vacuum chamber (102), and an outer cylinder (105) arranged sequentially from the inside to the outside. The vacuum chamber (102) is filled with a honeycomb thermal conductive structure (103) and an aerogel layer (104). A number of microcapsules are uniformly embedded in the honeycomb thermal conductive structure, and the microcapsules are filled with phase change material. The aerogel layer (104) is used to isolate the honeycomb thermal conductive structure (103) and the outer cylinder (105). The honeycomb thermal conductive structure (103) is used to store and release heat. The drain hole on the plug (9) passes through the inner cylinder (101) and extends into the vacuum chamber (102). The heat shield sleeve (1) is also provided with a unidirectional heat conduction unit (106), which is used to guide external heat into the vacuum chamber (102) in one direction.

2. The fire hydrant antifreeze and leakage monitoring device according to claim 1, characterized in that, The honeycomb thermally conductive structure is embedded within the aerogel layer.

3. The fire hydrant antifreeze and leakage monitoring device according to claim 1, characterized in that, The phase change material is a composite of tetradecane and expanded graphite.

4. The fire hydrant antifreeze and leakage monitoring device according to claim 1, characterized in that, The surface of the microcapsules is sputtered with a selective absorption coating.

5. A fire hydrant antifreeze and leakage monitoring device according to any one of claims 1 to 4, characterized in that, The unidirectional heat conduction unit (106) includes a plurality of copper-water gravity heat pipes (1061), which are evenly distributed around the heat shield sleeve (1); one end of the copper-water gravity heat pipe (1061) extends into the frozen soil layer (6), and the other end passes through the outer cylinder (105) and extends into the vacuum cavity (102). The copper-water gravity heat pipe (1061) is equipped with a one-way valve plate.

6. A fire hydrant antifreeze and leakage monitoring device according to any one of claims 1 to 4, characterized in that, It also includes a Y-type micro-permeation diverter, which includes a Y-type copper pipe connected to the drain hole. The two outlets of the Y-type copper pipe are respectively connected to the large-diameter main pipe (2) and the small-diameter branch pipe (3). The large-diameter main pipe (2) extends downward through the heat shield sleeve (1) and into the gravel layer (7). The outlet of the small-diameter branch pipe (3) is connected to a hydrophilic cotton rope (4). The hydrophilic cotton rope (4) extends upward through the heat shield sleeve (1) and is connected to the water mirror pad (5). The water mirror pad (5) is fitted onto the plug body (9) and is located between the flange of the plug body (9) and the ground. The water mirror pad (5) contains a humidity sensing unit.

7. A fire hydrant antifreeze and leakage monitoring device according to claim 6, characterized in that, The inlet of the small-diameter branch pipe (3) is lower than the inlet of the large-diameter main pipe (2).

8. A fire hydrant antifreeze and leakage monitoring device according to claim 6, characterized in that, The water mirror pad (5) includes a sensing pad layer (501), a composite layer (503) and a protective layer (504) arranged sequentially from bottom to top. The sensing pad (501) adopts a capacitive grid structure composed of polyimide and graphene, and polymer optical fiber microbending sensing fiber (502) is embedded in the sensing pad (501). The composite layer (503) includes a vertically contactable, separable friction layer and a piezoelectric film integrated on the back side of the sensing pad layer (501); A capacitive humidity chip is also attached to the back of the sensing pad (501).

9. A fire hydrant antifreeze and leakage monitoring device according to any one of claims 1 to 4, characterized in that, The inner wall of the outer cylinder (105) is provided with compressible corrugated sections.

10. A fire hydrant antifreeze and leakage monitoring device according to any one of claims 1 to 4, characterized in that, It also includes an anti-freeze ring (8), which is disposed on the outside of the outer cylinder (105); the anti-freeze ring (8) includes a closed-cell foam board in the inner layer and crushed stone in the outer layer.

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