Cable trench cover plate with adaptive dehumidification and water removal and anti-condensation function

Abstract

This invention discloses a cable trench cover with adaptive dehumidification and anti-condensation functions, belonging to the field of power cable trench protection technology. The cover, from top to bottom, comprises a wear-resistant protective layer, an upper phase change layer, a transition thermally conductive layer, a middle phase change layer, a thermal insulation layer, a lower phase change layer, and a sealing base layer. The three phase change layers contain first, second, and third phase change materials with different phase change temperatures, decreasing sequentially. Each phase change layer contains thermally conductive fillers, causing its thermal conductivity to decrease gradually from top to bottom. This invention, through the graded heat storage and release of multi-stage phase change materials, synergistically reduces the surface temperature fluctuation of the cover by more than 80%, eliminating the thermodynamic conditions for condensation at the source. It features excellent anti-condensation performance, requires no external energy source, and has a long service life, making it suitable for various power cable trench projects.

Description

Technical Field

[0001] This invention relates to the field of power cable trench protection technology, specifically to cable trench covers with adaptive dehumidification and anti-condensation functions. Background Technology

[0002] As a crucial component of urban power transmission systems, power cable trenches bear the responsibility of laying high-voltage and low-voltage power cables, and their safe operation directly impacts the reliability of urban power supply. Cable trenches are typically located underground or semi-underground. Due to the relatively enclosed space and poor air circulation within the trench, coupled with the heat generated by the cables themselves, the internal environment of the cable trench becomes complex and variable. Under these unique environmental conditions, cable trench covers, acting as a physical barrier between the cable trench and the external environment, not only need to withstand the loads of vehicles and pedestrians, but more importantly, they bear the vital function of regulating the internal environment and protecting the safety of the cables.

[0003] From a technical perspective, anti-condensation technology for cable trench covers involves multiple disciplines, including thermodynamics, heat transfer, and materials science. The fundamental cause of condensation is that the surface temperature of an object is lower than the dew point temperature of the surrounding air. When warm, humid air comes into contact with a cooler surface, water vapor in the air condenses into liquid water. In cable trench environments, due to large diurnal temperature variations and high humidity, traditional concrete or metal covers often become high-risk areas for condensation. The long-term presence of condensate not only accelerates the corrosion of metal components but can also lead to short circuits at cable joints, seriously affecting the safe and stable operation of the power system.

[0004] Furthermore, cable trenches often experience a certain amount of water accumulation or high humidity. These sources include groundwater seepage, rainwater infiltration through gaps in the cover plates, and condensation on the trench walls. If this water cannot be drained promptly, it will further exacerbate the humidity within the trench, creating a vicious cycle of condensation. Therefore, the cover plates not only need to prevent surface condensation but also need to guide and facilitate the drainage of moisture from within the cable trench.

[0005] In existing technologies, engineers have proposed various solutions to prevent condensation on cable trench covers. Traditional anti-condensation methods mainly employ passive strategies, addressing the issue after condensation occurs through ventilation, heating, or dehumidification. For example, some solutions involve installing forced ventilation systems inside the cable trench to reduce humidity by increasing airflow; others use electric heating elements to heat the cover, raising its surface temperature to prevent condensation. Some technologies also address the issue from a material perspective, using insulation materials to reduce the impact of external temperature fluctuations. Regarding moisture removal, some existing technologies incorporate drainage holes or ventilation slots in the cover, but these often suffer from low drainage efficiency, susceptibility to clogging, and compromised cover strength due to their simple structure.

[0006] After in-depth analysis of existing technologies, the current cable trench cover anti-condensation and dehumidification technologies have the following fundamental technical defects: First, traditional technical solutions generally suffer from a passive response problem, meaning that protective measures can only be activated after condensation has occurred or is about to occur, lacking preventative control capabilities. This reactive approach often lags behind in the face of rapid temperature changes and cannot fundamentally eliminate the conditions that lead to condensation.

[0007] Second, the existing technical solutions suffer from insufficient thermal inertia. From a thermodynamic perspective, ordinary concrete or metal covers have relatively small heat capacity and are extremely sensitive to changes in external temperature. When the ambient temperature changes drastically, the cover temperature will change rapidly, causing the cover surface temperature to frequently fall below the air dew point temperature, creating conditions for condensation. This temperature following effect is particularly pronounced in climatic conditions where the diurnal temperature range reaches 15-25℃.

[0008] Third, the existing technology solutions lack sufficient moisture removal capabilities. Most cover products rely solely on gravity drainage or simple vents for moisture exchange, resulting in low drainage efficiency. Furthermore, the vents are prone to water ingress during rainy weather, which actually increases humidity within the trench. The lack of structured drainage path design and backflow prevention measures makes it difficult to drain accumulated water from the cable trench in a timely manner.

[0009] Fourth, existing technical solutions have poor environmental adaptability. Most anti-condensation covers are designed with fixed parameters and cannot be adaptively adjusted according to different climatic conditions and seasonal changes. This lack of environmental adaptability greatly limits the applicability and practical value of the technical solutions.

[0010] Fifth, from the perspective of materials science, functional materials in existing technologies often have stability issues. For example, although some phase change materials have good heat storage performance, they are prone to phase separation after multiple phase change cycles, leading to performance degradation; or some thermally conductive fillers are unevenly dispersed in the matrix material, forming discontinuous thermal conductive channels, which affects the overall thermal conductivity.

[0011] Sixth, existing technologies also have significant shortcomings in energy consumption control. Active anti-condensation systems typically require continuous electrical energy to maintain the cover temperature, which not only increases operating costs but also contradicts the current technological development trend of energy conservation and emission reduction. Summary of the Invention

[0012] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a cable trench cover with adaptive dehumidification and anti-condensation functions.

[0013] To achieve the aforementioned objective, the technical solution of the present invention is implemented as follows: a cable trench cover with adaptive dehumidification and anti-condensation functions includes, from top to bottom, the following layers stacked sequentially: a wear-resistant protective layer, an upper phase change layer, a transition heat-conducting layer, a middle phase change layer, a heat insulation layer, a lower phase change layer, and a sealing base layer.

[0014] The upper phase change layer contains a first phase change material and has a first phase change temperature; the middle phase change layer contains a second phase change material and has a second phase change temperature; the lower phase change layer contains a third phase change material and has a third phase change temperature. The first, second, and third phase change temperatures are all different, with the first phase change temperature > the second phase change temperature > the third phase change temperature. The upper, middle, and lower phase change layers together constitute a multi-stage phase change material composite structure. Furthermore, each of the above phase change layers contains thermally conductive fillers, causing the thermal conductivity of each phase change layer to decrease gradually from top to bottom, with the upper phase change layer having the highest thermal conductivity and the lower phase change layer having the lowest. This is used for the graded storage and release of heat within different temperature ranges, and the synergistic effect reduces the surface temperature fluctuation of the cover plate by more than 80%.

[0015] To achieve the dehumidification and water removal function, the cover plate is also equipped with a dehumidification and water removal structure. The dehumidification and water removal structure includes: several drainage micro-grooves spaced apart along the width of the cover plate, which are opened on the upper surface of the cover plate, extend along the length of the cover plate, and have a drainage slope that slopes downward from the center of the cover plate to the edge of the cover plate; a one-way vent valve installed in the sealing base layer, which connects the inside of the cable trench with the external environment, allowing water vapor and air inside the cable trench to be discharged in a set direction and preventing external moisture from flowing back in; and a drainage guide groove installed on the side wall of the cover plate, which is used to guide the accumulated water to the edge of the cover plate for discharge.

[0016] Preferably, the first phase transition temperature is 28-30℃, the second phase transition temperature is 22-25℃, and the third phase transition temperature is 18-20℃.

[0017] Preferably, the first phase change material, the second phase change material, and the third phase change material are each independently a paraffin-based organic phase change material system, and all are encapsulated using microencapsulation technology. The microcapsule wall material is melamine resin, and the microcapsule particle size is 10-50 μm.

[0018] More preferably, the first phase change material is n-octacosane, with a latent heat of phase change of 240-250 kJ / kg, a microcapsule particle size of 15-25 μm, and a microcapsule packing density in the phase change layer of 650 kg / m³; the second phase change material is a mixture of n-eicosane and n-docosane, with a latent heat of phase change of 220-230 kJ / kg, a microcapsule particle size of 20-30 μm, and a microcapsule packing density in the phase change layer of 600 kg / m³; the third phase change material is a mixture of n-octacosane and n-eicosane, with a latent heat of phase change of 200-210 kJ / kg, a microcapsule particle size of 25-35 μm, and a microcapsule packing density in the phase change layer of 550 kg / m³.

[0019] Preferably, graphene nanosheets (GNPs) are independently added to the upper, middle, and lower phase change layers as thermally conductive fillers to form a three-dimensional thermally conductive network (3D-TN) in the phase change material matrix. The graphene nanosheets (GNPs) have a diameter of 2-5 μm and a thickness of 5-10 nm, and are surface functionalized with a silane coupling agent.

[0020] More preferably, the amount of graphene nanosheets (GNP) added in the upper phase change layer is 8 wt%, the amount of graphene nanosheets (GNP) added in the middle phase change layer is 7 wt%, and the amount of graphene nanosheets (GNP) added in the lower phase change layer is 6 wt%.

[0021] Preferably, the thermal conductivity of the cover plate cross section is gradient-distributed, with the thermal conductivity of the upper phase change layer region: the thermal conductivity of the middle phase change layer region: the thermal conductivity of the lower phase change layer region being 1:0.7:0.5.

[0022] Preferably, the width of the drainage micro-groove is 2-5mm, the depth is 5%-10% of the cover plate thickness, and the slope of the drainage slope is 2%-5%.

[0023] Preferably, the opening pressure of the one-way vent valve is 50-200Pa, and a dust filter is provided at the air outlet.

[0024] Preferably, a microchannel heat transfer enhancement structure is further provided in the middle phase change layer, which includes microchannel tubes embedded in the middle phase change layer. The microchannel tubes are made of thin-walled stainless steel tubes and arranged in a serpentine path; the inside of the microchannel tubes is filled with microchannel internal phase change material with a phase change temperature of 20-25℃, and the outer surface is coated with a thermally conductive silicone coating; the diameter of the microchannel tubes is 2-3mm, and the arrangement spacing is 10-15mm; short-cut carbon fibers are also arranged around the microchannel tubes as local thermal conductivity reinforcement, the length of the short-cut carbon fibers is 3-5mm, and the addition amount is 2wt%.

[0025] Preferably, the transition heat-conducting layer is made of graphite cement-based material with a thermal conductivity of 4.5 W / (m·K); the heat insulation layer is made of aerated concrete material with a thickness of 15 mm; and the sealing base layer is made of high-strength concrete with a 28-day compressive strength of not less than C40 standard.

[0026] Preferably, the wear-resistant protective layer is a transparent polyurethane protective coating with a thickness of 1-2 mm and a water vapor permeability of 50-100 g / (m²·24h) in the thickness direction.

[0027] Preferably, the cover plate also has an environmental adaptive control function. This function includes: a sensor assembly integrated within the cover plate, comprising at least a temperature sensor, a humidity sensor, and a solar radiation sensor; a microcontroller electrically connected to the sensor assembly, used to run a dew point temperature prediction algorithm based on historical meteorological data and real-time sensor data to generate a control signal; and an adjustable thermal conductive component, disposed in the transition thermal conductive layer and electrically connected to the microcontroller, used to change its own thermal conductivity path state according to the control signal, thereby adjusting the rate of heat transfer from the upper phase change layer to the middle phase change layer, to dynamically adjust the working state of each phase change material layer. This lightweight active adjustment further ensures the anti-condensation effect under extreme climatic conditions.

[0028] More preferably, the adjustable thermal conductive component includes multiple micro thermal switching units arranged in parallel. Each micro thermal switching unit includes: a first thermally conductive block and a second thermally conductive block fixedly disposed in the transition thermally conductive layer, and a movable thermally conductive bridge disposed between the first thermally conductive block and the second thermally conductive block. The thermally conductive bridge is driven by a shape memory alloy (SMA) actuator. The thermal deformation of the SMA enables the thermally conductive bridge to contact or separate from the thermally conductive blocks on both sides, thereby forming the conduction or disconnection of the thermal conductive path. The SMA actuator is electrically connected to a microcontroller and is driven by the microcontroller applying current pulses.

[0029] The present invention also provides a method for preparing the above-mentioned cable trench cover, comprising the following steps: Step 1: Preparation of Phase Change Material Microcapsules (PCMs). Using phase change material as the core material and melamine resin as the wall material, an in-situ polymerization reaction is carried out. Specifically, the core material is heated to a liquid state and dispersed into tiny droplets under the action of an emulsifier. Then, a prepolymer is added, and the polymerization reaction is carried out under acidic conditions, with the temperature controlled at 60-70℃ and the reaction time at 4-6 hours, to obtain microcapsules with uniform particle size distribution.

[0030] Step 2: Pretreatment of graphene nanosheets (GNP). The graphene surface is functionalized using a silane coupling agent. Specifically, graphene is dispersed in a 95% ethanol solution, 3-aminopropyltriethoxysilane is added, and the mixture is stirred at 60°C for 2 hours. The mixture is then filtered and dried to obtain functionalized graphene.

[0031] Step 3: Preparation of composite phase change materials. The prepared phase change material microcapsules (PCM) are mixed with functionalized graphene (GNP) in a certain proportion and mixed using a high-speed disperser at 3000 rpm for 30 minutes to uniformly disperse the graphene and form a continuous three-dimensional thermally conductive network (3D-TN), thus obtaining the upper phase change composite material, the middle phase change composite material, and the lower phase change composite material.

[0032] Step Four: Layered Casting and Shaping. A layered casting process is adopted, casting the sealing base layer, lower phase change layer, thermal insulation layer, middle phase change layer, transition thermal conductive layer, and upper phase change layer sequentially from bottom to top. Polymer-modified cement mortar is used as a binder between each layer to ensure a strong bond. The thickness of the sealing base layer is 30mm, the lower phase change layer is 20mm, the thermal insulation layer is 15mm, the middle phase change layer is 25mm, the transition thermal conductive layer is 10mm, and the upper phase change layer is 15mm.

[0033] Step 5: Integration of dehumidification and water removal structures. Install a one-way vent valve at a predetermined position on the sealed base layer, with the valve's inlet facing the inside of the cable trench and the outlet facing the external environment. Install a dust filter at the outlet. Machining is used to create several drainage micro-grooves extending along the length of the cover plate on its upper surface. The bottom of the drainage micro-grooves has a drainage slope that slopes downwards from the center of the cover plate to its edge, with a slope of 2%-5%. Drainage guide grooves are machined into the side walls of the cover plate, and these guide grooves are connected to the ends of the drainage micro-grooves.

[0034] Step Six: Surface Treatment and Encapsulation. Apply a transparent polyurethane protective coating as a wear-resistant protective layer to the surface of the cover plate, with a thickness of 1-2 mm.

[0035] When the cable trench cover includes a microchannel heat transfer enhancement structure, the preparation method also includes the microchannel preparation and integration steps between steps three and four: the arrangement parameters of the microchannels are determined according to thermodynamic calculations, and a microchannel tube with a serpentine path arrangement is made by laser cutting and bending forming of a stainless steel thin-walled tube; a thermally conductive silicone coating is applied to the outer surface of the microchannel tube; liquid phase change material is filled into the microchannel tube using a vacuum infusion process, the vacuum is evacuated to below 0.01 MPa, the vacuum state is maintained for 30 minutes, and the phase change material is formed inside the microchannel after cooling; the filled microchannel tube is pre-embedded in the middle phase change layer, and short-cut carbon fibers are arranged around it.

[0036] When the cable trench cover includes an environmental adaptive control function, the manufacturing method also includes synchronously pre-embedding sensor components and a microcontroller in step four, and installing adjustable heat-conducting components in the transition heat-conducting layer.

[0037] The beneficial effects of this invention are reflected in: This invention significantly improves the thermal inertia of the cover plate by introducing a multi-stage phase change material system with high heat storage density, enabling the cover plate temperature to buffer and delay changes in the external ambient temperature. Based on the thermal regulation mechanism of latent heat of phase change, the temperature fluctuation range of the cover plate surface can be reduced by more than 80%. When the external ambient temperature undergoes a drastic change of 15-25°C, the temperature change range of the cover plate surface is only 3-5°C, ensuring that the cover plate surface temperature remains above the air dew point temperature, fundamentally eliminating the thermodynamic conditions for condensation.

[0038] By incorporating a combination of drainage micro-channels, drainage slopes, and one-way vent valves, the directional guidance and active drainage of moisture inside the cable trench are achieved. The slope design of the drainage micro-channels allows accumulated water and condensation on the upper surface of the cover to flow naturally towards the edge of the cover using gravity; the one-way vent valve ensures the continuous outward diffusion of water vapor inside the cable trench, while effectively preventing backflow of external rainwater. The drainage micro-channels and one-way vent valves work together to achieve a dual dehumidification function of "preventing water accumulation on the upper surface and guiding moisture inside," fundamentally reducing the humidity level inside the cable trench and creating favorable environmental conditions for preventing condensation.

[0039] The anti-condensation effect is excellent. Compared with traditional covers, the condensation rate of the cable trench cover solution of this invention is effectively reduced.

[0040] Through the synergistic working mechanism of the three-stage phase change materials, this invention maintains excellent anti-condensation performance over a wide temperature range of -20℃ to +45℃. At low temperatures, the lower phase change layer (18-20℃) plays a major role; at normal temperatures, the middle phase change layer (22-25℃) undertakes the task of thermal regulation; and at high temperatures, the upper phase change layer (28-30℃) provides thermal buffering, ensuring that the cover plate maintains optimal anti-condensation performance under various climatic conditions.

[0041] The phase change material is encapsulated in microencapsulation to avoid leakage and phase separation problems that may occur during multiple phase change cycles. According to the results of accelerated aging tests, the cover plate using the technology of this invention still retains more than 95% of the latent heat of phase change after 1000 phase change cycles, and the estimated actual service life can reach more than 15 years, which fully meets the long-term use requirements of power infrastructure.

[0042] This invention utilizes the passive heat storage characteristics of phase change materials to achieve an anti-condensation effect superior to most active solutions without consuming external energy. A standard cable trench cover (600mm×600mm×100mm) using this technology can save approximately 150-200 kWh of electricity annually, demonstrating significant energy-saving benefits.

[0043] By using the optional environmental adaptive control components, without changing the passive working nature of the cover plate, the power consumption can be finely adjusted only at the milliwatt level when necessary, ensuring zero condensation even under historically rare extreme weather conditions, thus improving the robustness of the entire system. Attached Figure Description

[0044] In the attached diagram: Figure 1 This is a schematic diagram of the overall structure of the cable trench cover with adaptive dehumidification and anti-condensation functions of the present invention. It shows the multi-layer composite structure of the cover, including a wear-resistant protective layer (1), an upper phase change layer (2), a transition heat-conducting layer (3), a middle phase change layer (4), a heat insulation separation layer (5), a lower phase change layer (6), and a sealing base layer (7).

[0045] Figure 2 This is a schematic diagram of the microchannel heat transfer enhancement structure of the present invention, wherein (a) is a top view of the microchannel arrangement, showing the serpentine arrangement and spacing (L) of the microchannel tubes (4a); (b) is a schematic diagram of the microchannel cross-section structure, showing the diameter (D) of the microchannel tube (4a), the thermally conductive silicone coating (4d) on the outer surface, the phase change material (4b) inside the microchannel and the surrounding short-cut carbon fibers (4c); (c) is a schematic diagram of the heat transfer principle, illustrating the heat transfer mechanism and phase change working process.

[0046] Figure 3 This is a flowchart illustrating the working principle of the multi-stage phase change material adaptive anti-condensation of the present invention. It shows the complete control logic from ambient temperature monitoring, temperature range judgment, corresponding phase change layer activation, heat absorption / release to temperature fluctuation reduction and condensation prevention.

[0047] Figure 4 This is a schematic diagram of the graphene thermal conductive network structure of the present invention, wherein (a) is a schematic diagram of the microstructure of graphene nanosheets (GNP), showing its hexagonal grid structure and size parameters; (b) is a schematic diagram of the formation process of the three-dimensional thermal conductive network (3D-TN), showing the distribution state of graphene in the phase change material matrix; and (c) is a schematic diagram of the overall structure of the phase change material microcapsule (PCM) / graphene (GNP) composite material, showing the distribution of microcapsules and the connection of thermal conductive channels. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0049] It should be noted that if the embodiments of the invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0050] Furthermore, "multiple" refers to two or more. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the invention.

[0051] Please refer to the instruction manual appendix. Figures 1-4 This invention provides a cable trench cover with adaptive dehumidification and anti-condensation functions, which is suitable for cable trench cover renovation projects in areas with complex climate conditions and large temperature differences between day and night, especially urban power grid systems located in subtropical monsoon climate zones.

[0052] like Figure 1 As shown, the cable trench cover plate includes the following layers stacked from top to bottom: wear-resistant protective layer 1, upper phase change layer 2, transition heat-conducting layer 3, middle phase change layer 4, heat insulation layer 5, lower phase change layer 6, and sealing base layer 7.

[0053] In this embodiment, the phase change material is a paraffin-based organic phase change material system, which is encapsulated using microencapsulation technology. The specific configuration is as follows: The upper phase change layer 2 uses n-octacosane as the main component, with a phase change temperature range of 28-30℃ and a latent heat of phase change of 240-250kJ / kg. The microcapsule wall material is melamine resin, the capsule particle size is controlled between 15-25μm, and the filling density is 650kg / m³.

[0054] The middle phase change layer 4 is a mixture of n-eicosane and n-docosane. By adjusting the mixing ratio, the phase change temperature is precisely controlled at 22-25℃, the latent heat of phase change is 220-230kJ / kg, the capsule particle size is 20-30μm, and the filling density is 600kg / m³.

[0055] The lower phase change layer 6 adopts a mixed system of n-octadecane and n-eicosane, with a phase change temperature set at 18-20℃, a latent heat of phase change of 200-210kJ / kg, a capsule particle size of 25-35μm, and a filling density of 550kg / m³.

[0056] Graphene nanosheets (GNPs) are also added to each phase change layer as thermally conductive fillers. The GNPs have a diameter of 2-5 μm and a thickness of 5-10 nm, and are surface-functionalized using a silane coupling agent. The amount of GNPs added in the upper phase change layer 2 is 8 wt%, in the middle phase change layer 4 it is 7 wt%, and in the lower phase change layer 6 it is 6 wt%. The GNPs form a three-dimensional thermally conductive network (3D-TN) in the phase change material matrix. The thermal conductivity of the upper phase change composite material 2 with 8 wt% graphene added reaches 3.2 W / (m·K), which is 16 times higher than that of the pure phase change material (0.2 W / (m·K).

[0057] The transitional heat-conducting layer 3 is made of graphite cement-based material with a thermal conductivity of 4.5 W / (m·K). The thermal insulation layer (5) is made of aerated concrete with a thickness of 15 mm. The sealing base layer 7 is made of high-strength concrete, using PO 42.5 ordinary Portland cement as cement, with river sand (fineness modulus 2.6-2.9) as fine aggregate, and 5-10 mm continuously graded crushed stone as coarse aggregate. The water-cement ratio is 0.35, and the 28-day compressive strength is not lower than the C40 standard. The wear-resistant protective layer 1 is a transparent polyurethane protective coating with a thickness of 1-2 mm and is permeable to water vapor.

[0058] The method for preparing the cable trench cover is as follows: Step 1: Preparation of phase change material microcapsules (PCMs). Using in-situ polymerization, the phase change material is heated to a liquid state and dispersed into tiny droplets under the action of an emulsifier. Then, melamine resin prepolymer is added, and polymerization is carried out under acidic conditions. The temperature is controlled at 60-70℃, and the reaction time is 4-6 hours, yielding microcapsules with uniform particle size distribution.

[0059] Step 2: Pretreatment of graphene nanosheets (GNP). Graphene was dispersed in a 95% ethanol solution, and 3-aminopropyltriethoxysilane was added. The mixture was stirred at 60°C for 2 hours, then filtered and dried to obtain functionalized graphene.

[0060] Step 3: Preparation of composite phase change materials. The prepared phase change material microcapsules (PCM) are mixed with functionalized graphene (GNP) in a certain proportion and mixed using a high-speed disperser at 3000 rpm for 30 minutes to uniformly disperse the graphene and form a continuous three-dimensional thermally conductive network (3D-TN), thus obtaining the upper phase change composite material, the middle phase change composite material, and the lower phase change composite material.

[0061] Step Four: Layered Casting and Shaping. A layered casting process is adopted. First, the sealing base layer 7 (high-strength concrete, 30mm thick) is poured. After initial setting, the lower phase change composite material layer 6 (20mm thick) is laid. Next, the thermal insulation layer 5 (aerated concrete, 15mm thick) is poured. Then, the middle phase change composite material layer 4 (25mm thick) is laid. Next, the transition thermally conductive layer 3 (graphite cement-based material, 10mm thick) is laid. Finally, the upper phase change composite material layer 2 (15mm thick) is laid. Polymer-modified cement mortar is used as a binder between the layers to ensure a strong interlayer bond.

[0062] Step 5: Surface treatment and encapsulation. Apply a transparent polyurethane protective coating as a wear-resistant protective layer (1) to the surface of the cover plate, with a thickness of 1-2 mm.

[0063] The working principle of this embodiment is as follows: When the ambient temperature rises, heat flows downward from the upper surface of the cover plate. First, it passes through the upper phase change layer 2, where the phase change material absorbs heat and undergoes a phase change (solid to liquid) within the range of 28-30℃, delaying the temperature rise; then, the heat flows through the transition heat-conducting layer 3, which quickly guides the heat flow to diffuse to both sides; next, it reaches the middle phase change layer 4, where it further absorbs heat within the range of 22-25℃; finally, it passes through the insulation layer 5, where most of the heat is confined to the upper half of the cover plate, preventing heat from being transferred into the cable trench. When the ambient temperature decreases, each phase change material layer releases the stored heat (liquid to solid) in sequence, maintaining a relatively stable cover plate temperature.

[0064] Example 2 Based on Example 1, this embodiment further integrates a microchannel heat transfer enhancement structure inside the cover plate, making it suitable for special occasions with high requirements for anti-condensation performance, such as cable trenches for important loads and substation inlet / outlet trenches.

[0065] like Figure 2 As shown, a microchannel heat transfer enhancement structure is provided in the middle phase change layer 4. The microchannel tubes 4a are made of thin-walled stainless steel tubes with an outer diameter of 3 mm and an inner diameter of 2.5 mm. The spacing (L) is 12 mm, arranged in a serpentine path, and the total length is determined according to the size of the cover plate to ensure effective coverage of the entire cover plate area. The phase change material 4b filled inside the microchannel tubes 4a has a phase change temperature of 20-25℃ (using a mixture of n-eicosane and a phase change temperature regulator).

[0066] The fabrication and integration methods of microchannel heat transfer enhancement structures are as follows: First, the optimal arrangement parameters of the microchannels (diameter D=2-3mm, spacing L=10-15mm) are determined based on thermodynamic calculations. Microchannel tubes 4a are fabricated in a serpentine path using stainless steel thin-walled tubes through laser cutting and bending forming processes, ensuring that the bending radius is not less than 3 times the tube diameter.

[0067] Secondly, a 0.2 mm thick thermally conductive silicone coating 4d is uniformly coated on the outer surface of the microchannel tube 4a to enhance the interfacial bonding with the surrounding phase change material and reduce the contact thermal resistance.

[0068] Then, a vacuum infusion process is used to fill the microchannel tube 4a with liquid phase change material. The microchannel tube 4a is placed in a vacuum chamber, and the vacuum is evacuated to below 0.01 MPa. Then, the phase change material heated to a liquid state is injected, and the vacuum state is maintained for 30 minutes to ensure that there are no air bubbles left inside the channel. Finally, it is cooled to room temperature, and the phase change material solidifies to form phase change material 4b inside the microchannel, and the infusion port is sealed.

[0069] Next, the microchannel tube 4a filled with phase change material is pre-embedded in the middle phase change layer 4 and tightly bonded to the phase change material.

[0070] Finally, short-cut carbon fibers 4c are arranged around the microchannel tube 4a as a local thermally conductive reinforcement. The length of the short-cut carbon fibers 4c is 3-5 mm and the addition amount is 2 wt%. A radial thermally conductive channel is formed around the microchannel tube, which further enhances the heat exchange efficiency between the microchannel and the surrounding phase change material.

[0071] The effective heat transfer area of ​​the microchannel heat transfer enhancement structure is about 3-5 times larger than that of the planar structure, enabling the phase change material to respond more quickly to changes in external temperature and improve thermal regulation efficiency.

[0072] Example 3 Based on Embodiment 1 or 2, this embodiment further integrates environmental adaptive control functions, enabling the cover plate to have the ability to actively prevent extreme weather conditions while operating in a completely passive manner.

[0073] The cover plate is embedded with a low-power adaptive control system, specifically including: Sensor components: A digital temperature sensor (accuracy ±0.1℃), a capacitive humidity sensor (accuracy ±2%RH), and a patch-type total solar radiation sensor are pre-embedded on the upper surface of the upper phase change layer 2 or in the transition thermal conductive layer 3 to collect environmental parameters of the cover plate in real time.

[0074] Microcontroller: Employs a low-power ARM Cortex-M4 processor, housed in a waterproof junction box on the side wall of the cover plate, and communicates with sensors via an I²C bus. The microcontroller has built-in Flash memory pre-stored with nearly 10 years of historical meteorological data (temperature, humidity, dew point) for the local area, and runs a time-series-based dew point temperature prediction model (using the ARIMA algorithm). Based on real-time data and historical trends, this model predicts the risk periods when the cover plate surface temperature may fall below the dew point 30 minutes in advance.

[0075] Adjustable thermal conductivity components: Located within the transition thermal conductivity layer 3, these components include multiple parallel micro-thermal switching units. Each thermal switching unit comprises a movable thermal bridge driven by a shape memory alloy (SMA). Normally, the thermal bridge is in close contact with the high thermal conductivity graphite cement on both sides under spring action, forming a low thermal resistance path. When the microcontroller predicts an extremely high risk of condensation (e.g., the surface temperature will be significantly lower than the dew point) and phase change heat storage alone may be insufficient, a short pulse current is applied to the SMA actuator. The SMA contracts, pulling the thermal bridge out of contact, partially cutting off the thermal path. This temporarily reduces the effective thermal conductivity of the transition thermal conductivity layer, slowing heat transfer to the lower layers and forcing the upper phase change layer 2 to absorb more heat and maintain a higher temperature. When the risk is eliminated, the SMA cools down and the thermal bridge re-engages.

[0076] This low-power active intervention is only activated when the passive phase change regulation margin is insufficient, resulting in extremely low total energy consumption over the entire life cycle. This ensures both reliability and maintains the inherent passive energy-saving characteristics of the system.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0078] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0079] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A cable trench cover with adaptive dehumidification and anti-condensation functions, characterized in that, Including those stacked sequentially from top to bottom: Abrasion-resistant protective layer (1); The upper phase change layer (2) contains a first phase change material, which has a first phase change temperature; Transition thermal conductive layer (3); The middle phase change layer (4) contains a second phase change material, which has a second phase change temperature; Insulation layer (5); The lower phase change layer (6) contains a third phase change material, which has a third phase change temperature; and sealing base layer (7); The first phase transition temperature, the second phase transition temperature, and the third phase transition temperature are all different. Thermally conductive fillers are added to the upper phase change layer (2), the middle phase change layer (4) and the lower phase change layer (6) so that the thermal conductivity of each phase change layer decreases in a gradient from top to bottom, with the upper phase change layer (2) having the largest thermal conductivity and the lower phase change layer (6) having the smallest thermal conductivity. The upper phase change layer (2), the middle phase change layer (4), and the lower phase change layer (6) together constitute a multi-level phase change material composite structure; The cover plate is also provided with a moisture-removing and water-eliminating structure, which includes: Multiple drainage micro-grooves (8) are formed on the upper surface of the cover plate. The drainage micro-grooves (8) extend along the length of the cover plate. The bottom of each drainage micro-groove (8) has a drainage slope that slopes downward from the center of the cover plate to the edge of the cover plate. The one-way vent valve (9) installed in the sealing base layer (7) connects the inside of the cable trench with the external environment and is configured to allow water vapor and air inside the cable trench to be discharged to the external environment in one direction, and to prevent external moisture from flowing back into the cable trench. And a drainage guide groove (10) provided on the side wall of the cover plate, wherein the drainage guide groove (10) is connected to the end of the drainage micro-groove (8).

2. The cable trench cover according to claim 1, characterized in that, The first phase transition temperature > the second phase transition temperature > the third phase transition temperature, wherein the first phase transition temperature is 28-30℃, the second phase transition temperature is 22-25℃, and the third phase transition temperature is 18-20℃.

3. The cable trench cover according to claim 1, characterized in that, The first, second, and third phase change materials are each independently paraffin-based organic phase change materials, and all are encapsulated using microencapsulation technology. The microcapsule wall material is melamine resin, and the microcapsule particle size is 10-50 μm. The first phase change material is n-octacosane, with a latent heat of phase change of 240-250 kJ / kg, a microcapsule particle size of 15-25 μm, and a microcapsule filling density of 650 kg / m³ in the phase change layer. The second phase change material is a mixture of n-eicosane and n-docosahexanes, with a latent heat of phase change of 220-230 kJ / kg, a microcapsule particle size of 20-30 μm, and a microcapsule packing density of 600 kg / m³ in the phase change layer; the third phase change material is a mixture of n-octadecane and n-eicosane, with a latent heat of phase change of 200-210 kJ / kg, a microcapsule particle size of 25-35 μm, and a microcapsule packing density of 550 kg / m³ in the phase change layer.

4. The cable trench cover according to claim 1, characterized in that, The thermally conductive filler is graphene nanosheets, which form a three-dimensional thermally conductive network in the phase change material matrix; the graphene nanosheets have a diameter of 2-5 μm and a thickness of 5-10 nm, and are surface functionalized by silane coupling agent; the amount of graphene nanosheets added in the upper phase change layer (2) is 8 wt%, the amount of graphene nanosheets added in the middle phase change layer (4) is 7 wt%, and the amount of graphene nanosheets added in the lower phase change layer (6) is 6 wt%; the thermal conductivity of the cover plate cross section is gradient distributed, and the ratio of the thermal conductivity of the upper phase change layer (2), the middle phase change layer (4), and the lower phase change layer (6) is 1:0.7:0.

5.

5. The cable trench cover according to claim 1, characterized in that, The width of the drainage micro-groove (8) is 2-5mm, the depth is 5%-10% of the cover plate thickness, and the slope of the drainage slope is 2%-5%; the opening pressure of the one-way vent valve (9) is 50-200Pa, and a dust filter is provided at the outlet of the one-way vent valve (9).

6. The cable trench cover according to claim 1, characterized in that, The intermediate phase change layer (4) is further provided with a microchannel heat transfer enhancement structure, which includes a microchannel tube (4a) pre-embedded in the intermediate phase change layer (4). The microchannel tube (4a) is a stainless steel thin-walled tube arranged in a serpentine path. The diameter of the microchannel tube (4a) is 2-3 mm and the arrangement spacing is 10-15 mm. The microchannel tube (4a) is filled with a microchannel internal phase change material (4b) with a phase change temperature of 20-25℃, and the outer surface is coated with a thermally conductive silicone coating (4d). Short-cut carbon fibers (4c) are also arranged around the microchannel tube (4a) as a local thermally conductive reinforcement. The length of the short-cut carbon fibers (4c) is 3-5 mm and the addition amount is 2 wt%.

7. The cable trench cover according to claim 1, characterized in that, The transitional thermally conductive layer (3) is a graphite cement-based material layer with a thermal conductivity of 4.5 W / m². The thermal insulation layer (5) is an aerated concrete material layer with a thickness of 15mm; the sealing base layer (7) is a high-strength concrete layer with a 28-day compressive strength not lower than C40 standard; the wear-resistant protective layer (1) is a transparent polyurethane protective coating with a thickness of 1-2mm, and the water vapor permeability of the wear-resistant protective layer (1) in the thickness direction is 50-100g / .

8. The cable trench cover according to claim 1, characterized in that, The cover plate also has an environmental adaptive control function, including: The sensor assembly integrated within the cover plate includes at least a temperature sensor, a humidity sensor, and a solar radiation sensor; A microcontroller, electrically connected to the sensor assembly, is configured to run a dew point temperature prediction algorithm based on historical meteorological data and real-time sensor data to generate control signals. An adjustable thermal conductive component is disposed in the transition thermal conductive layer (3) and electrically connected to the microcontroller. The adjustable thermal conductive component is configured to change its own thermal conductive path state according to the control signal to adjust the rate at which heat is transferred from the upper phase change layer (2) to the middle phase change layer (4).

9. The cable trench cover according to claim 8, characterized in that, The adjustable thermally conductive component includes multiple micro thermally conductive units arranged in parallel. Each micro thermally conductive unit includes: a first thermally conductive block and a second thermally conductive block fixedly disposed in the transition thermally conductive layer (3), and a movable thermally conductive bridge disposed between the first thermally conductive block and the second thermally conductive block. The thermally conductive bridge is driven by a shape memory alloy actuator, and the thermal deformation of the shape memory alloy actuator enables the thermally conductive bridge to contact or separate from the first thermally conductive block and the second thermally conductive block. The shape memory alloy actuator is electrically connected to the microcontroller.

10. The method for preparing the cable trench cover according to any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Prepare phase change material microcapsules. Use phase change material as core material and melamine resin as wall material, and react in situ at 60-70℃ for 4-6 hours to obtain microcapsules. Step 2: Pretreatment of graphene nanosheets: Graphene nanosheets are dispersed in an ethanol solution, 3-aminopropyltriethoxysilane is added, and the mixture is stirred at 60°C for 2 hours. Then, the mixture is filtered and dried to obtain functionalized graphene nanosheets. Step 3: Mix the microcapsules and the functionalized graphene nanosheets in a certain proportion and disperse them at 3000 rpm for 30 minutes to make the functionalized graphene nanosheets uniformly dispersed in the microcapsule matrix and form a three-dimensional thermally conductive network, thereby obtaining the upper phase change composite material, the middle phase change composite material and the lower phase change composite material respectively. Step 4: Using a layered pouring process, pour the sealing base layer (7), lower phase change layer (6), thermal insulation layer (5), middle phase change layer (4), transition thermal conductive layer (3) and upper phase change layer (2) from bottom to top. Polymer modified cement mortar is used as the adhesive between each layer. Step 5: Integrate the dehumidification and water removal structure, install a one-way vent valve (9) in the sealing base layer (7), so that the air inlet of the one-way vent valve (9) faces the inside of the cable trench and the air outlet faces the external environment, and install a dust filter at the air outlet; open multiple drainage micro-grooves (8) extending along the length of the cover plate on the upper surface of the cover plate, and the bottom of the drainage micro-grooves (8) has a drainage slope that slopes downward from the center of the cover plate to the edge of the cover plate; process a drainage guide groove (10) on the side wall of the cover plate, so that the drainage guide groove (10) is connected to the end of the drainage micro-grooves (8); Step 6: Apply a wear-resistant protective layer to the surface of the cover plate (1); When the cable trench cover includes a microchannel heat transfer enhancement structure, a microchannel preparation and integration step is also included between step three and step four: a serpentine stainless steel microchannel tube is made, a thermally conductive silicone coating is applied to the outer surface of the microchannel tube, a phase change material is filled into the microchannel tube using a vacuum infusion process and sealed, the filled microchannel tube is pre-embedded in the middle phase change layer (4), and short-cut carbon fibers are arranged around the microchannel tube.

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