Active temperature control method and system for frozen soil road based on radiation refrigeration and phase change energy storage

Abstract

The invention discloses a frozen earth road active temperature control method and system based on radiation refrigeration and phase change energy storage, and the method comprises the steps: carrying out the grid division of a to-be-regulated frozen earth region, determining a to-be-determined layout point, obtaining the features of the frozen earth region of the to-be-determined layout point, and determining a particle search target function according to the features of a road; carrying out particle search to determine a temperature control layout point, laying a frozen soil road active temperature control system, carrying out laboratory calibration to obtain soil parameters and phase change material parameters of a frozen soil region, and carrying out a phase change energy storage cycle test at the temperature control layout point to obtain temperature control data to construct a flow velocity prediction model; and determining a system operation mode and a temperature difference adjustment amount according to an actual material temperature difference, and inputting the temperature difference adjustment amount into the flow velocity prediction model to adjust the flow velocity of the phase change material so as to perform active temperature control on the frozen soil road. The method not only can improve the efficiency and accuracy of active temperature control of the frozen soil road, but also has good interpretability, and can be directly applied to an active temperature control system of the frozen soil road.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of permafrost infrastructure temperature control protection and energy saving, and particularly relates to a permafrost highway active temperature control method and system based on radiation refrigeration and phase change energy storage, and is particularly suitable for foundation stability maintenance of permafrost highway, railway and oil pipeline infrastructure. BACKGROUND

[0002] The stability maintenance of permafrost infrastructure has long been facing the severe challenge of the freeze-thaw cycle of the permafrost layer. Taking the Qinghai-Tibet Highway as an example, it passes through about 550 kilometers of continuous permafrost area. The permafrost melts in summer, causing the subgrade to sink and the pavement to crack, and freezes in winter, causing uplift deformation. The annual maintenance cost is as high as hundreds of millions of yuan. The traditional solution mainly relies on low-temperature thermal siphon, which uses the temperature difference between cold air and permafrost in winter to guide the underground heat out through the phase change of the internal working medium to strengthen the freezing of permafrost. However, the thermal rod stops working in summer due to the increase of ambient temperature, and only relies on passive insulation layer to delay the melting of permafrost, which has limited effect. In addition, the vertical burial of the thermal rod leads to small coverage of cold energy, making it difficult to deal with the problem of deepening of the active layer of permafrost under climate warming.

[0003] In recent years, radiation refrigeration technology has attracted attention due to its "zero energy consumption cooling" characteristics. It achieves continuous heat dissipation during the day by reflecting sunlight (0.3-2.5 μm) and high radiation in the mid-infrared (8-13 μm atmospheric window). However, single radiation refrigeration material has limitations such as insufficient night heat dissipation and decreased efficiency in cloudy weather in permafrost scenarios. Although phase change energy storage (PCM) technology can buffer temperature fluctuations through phase change latent heat, traditional PCM systems rely on active cooling or complex heat exchange structures, which are difficult to adapt to harsh highland environments. The present application proposes a permafrost highway active temperature control method and system based on radiation refrigeration and phase change energy storage, which integrates passive refrigeration, energy storage regulation and intelligent response for efficient temperature control. It breaks through the seasonal and energy efficiency bottlenecks of existing technologies, provides dynamic cooling and precise control throughout the year, and realizes long-term stability of the permafrost layer. SUMMARY

[0004] The purpose of the present application is to provide a permafrost highway active temperature control method and system based on radiation refrigeration and phase change energy storage.

[0005] To achieve the above purpose, the present application is implemented according to the following technical solutions:

[0006] The present application comprises the following steps:

[0007] The permafrost area to be controlled is divided into a grid to determine the to-be-determined layout points, the permafrost area characteristics and highway characteristics of the to-be-determined layout points are obtained, the particle search target function is determined, the temperature control layout points are determined by particle search, and the permafrost highway active temperature control system is laid out;

[0008] Obtaining the soil parameters and phase change material parameters in the frozen soil region through laboratory calibration, and obtaining the frozen soil temperature variation, phase change material temperature variation and phase change material flow rate variation through the phase change energy storage cycle test at the temperature control layout point;

[0009] Constructing a flow rate prediction model according to the frozen soil temperature variation, the phase change material temperature variation, the phase change material flow rate variation, the soil parameters and the phase change material parameters;

[0010] Determining the system operation mode and temperature difference adjustment amount according to the actual material temperature difference, and inputting the temperature difference adjustment amount into the flow rate prediction model to adjust the phase change material flow rate for active temperature control of the frozen soil highway.

[0011] Further, the method for determining the temperature control layout point comprises:

[0012] Dividing the frozen soil region to be controlled into 1km×1km grids, taking the grid vertexes with a straight-line distance less than 500m from the highway as the to-be-determined layout points, and obtaining the frozen soil region characteristics and highway characteristics of the to-be-determined layout points; the frozen soil region characteristics include thermal stability grade, landform change rate and surface curvature; the highway characteristics include highway curvature, corner, width and disease point;

[0013] Determining a particle search target function according to the frozen soil region characteristics and highway characteristics of the to-be-determined layout points, and the expression is:

[0014] J(P)=α1·F cost +α2·F overlap -α3·F cover +α4·F risk

[0015]

[0016]

[0017] Wherein J(P) is the particle search target function, α1, α2, α3, α4 are search target weights, F cost is the layout cost function, N set is the number of temperature control layout points, w1, w2 are construction cost weight coefficients, is the landform change rate of the temperature control layout point i, C i is the surface curvature of the temperature control layout point i, F overlap is the action range coincidence degree function, A ij is the overlapping area of the action circles of the temperature control layout points i and j, F cover is the coverage range function, R risk is the set of temperature control layout points of the risk road section, P k is the road section range of the disease risk of the layout point k, Ω kI(S(k) - r) is the range of action circle for the layout point k, I(·) is the indicator function (1 if covered, 0 otherwise), S i D(i) is the thermal stability grade of permafrost for the temperature control layout point i i R(i) is the historical disease mark for the temperature control layout point i i R is the radius of curvature of the road;

[0018] The to-be-determined layout point is defined as a particle population, and the particle population is chaotically initialized, and the expression is:

[0019]

[0020] wherein x is the output value of the primary chaotic mapping at the tth iteration, x is the output value of the secondary chaotic mapping at the tth iteration, x t μ1 is a dynamic chaotic factor, T is the maximum number of iterations, b1, b2, and b3 are fractal function complexity parameters, S is the slope correlation sharpening coefficient, is the absolute value of the topographic change rate of the permafrost region;

[0021] The particle position is updated And the particle position is disturbed by Gaussian disturbance to obtain the disturbed particle position The expression is:

[0022]

[0023] wherein is the updated position of particle i at the t+1th iteration, w or is the inertia weight, η t = (1+t) -1 is the step factor, is the Levy operator, Γ(·) is the space-time modulation function, is the position change amount of particle i at the tth iteration, γ1 = 2-e -t / T is the adaptive stability index, γ2 = -0.5S z is the permafrost correlation skewness, S z is the permafrost characteristic index, is the curvature correlation scale, is the topographic change rate of particle i corresponding to the to-be-determined layout point, q is the integral variable, is the global optimal position at the tth iteration, D max is the maximum distance, m is the permafrost time window, is the permafrost temperature at τ, is the permafrost temperature mean value, is the permafrost temperature standard deviation, is the temperature of the phase change material at time t, is the average temperature of the phase change material, is the standard deviation of the temperature of the phase change material;

[0024] The particle search objective function is calculated by taking the optimal position of the population as the temperature control layout point, and the temperature control layout point is output when the maximum number of iterations is reached or the particle search objective function is reduced by less than 0.1% for 5 consecutive generations. The permafrost road active temperature control system is laid out according to the temperature control layout point.

[0025] Further, the method for constructing the flow rate prediction model comprises:

[0026] The soil parameters and phase change material parameters in the permafrost region are obtained through experimental calibration; the soil parameters include moisture content, soil thermal conductivity, thermal diffusivity, and volumetric heat capacity; the phase change material parameters include specific heat capacity of the phase change material, thermal conductivity of the phase change material, viscosity, and latent heat of phase change;

[0027] The permafrost road active temperature control system is adjusted at the temperature control layout point to obtain the corresponding permafrost temperature change and phase change material temperature change. The permafrost temperature change, phase change material temperature change, phase change material flow rate, soil parameters, and phase change material parameters are combined to form a temperature control dataset. The temperature control dataset is divided into a training set and a test set in a ratio of 6:3 using a random forest algorithm. The training set is used to train the flow rate prediction model, and the test set is used to evaluate the performance of the flow rate prediction model.

[0028] The flow rate prediction model is based on a BP network structure, including an input layer, a feature branch layer, a feature fusion layer, a hidden layer, and an output layer. The feature branch layer outputs soil parameter features, phase change material parameter features, and dynamic features through soil parameter branches, phase change material branches, and dynamic feature branches. The feature fusion layer cross-fuses the outputs of the feature branch layer to obtain fusion features. The hidden layer is used to capture the dynamic dependence relationship between the fusion features, the phase change material flow rate, and the permafrost temperature change, and to predict the phase change material flow rate according to the required reduced permafrost temperature.

[0029] The flow rate prediction model uses a composite loss function to evaluate the difference between the predicted value and the true value of the phase change material flow rate, and the expression is:

[0030]

[0031] wherein is the composite loss function, is the mean square error loss, λ1, λ2 are loss weight coefficients, N is the number of samples, ReLU(·) is the ReLU activation function, q actual is the actual heat flux, determined by the phase change material flow rate, density, specific heat capacity, and temperature difference, q maxThe maximum allowable heat flux is determined by the thermal conductivity, heat exchange area and frozen soil thickness, and ∈ is a safety threshold, The time t i The derivative of the predicted flow rate v pred , Δt is the time step, The flow rate change at time t+1.

[0032] Further, the method for actively controlling the temperature of the frozen soil road comprises:

[0033] The system operating mode and temperature difference adjustment amount are determined according to the frozen soil temperature and the safety temperature; the operating mode includes a radiation heat dissipation mode and a phase change cooling mode; the radiation heat dissipation mode continuously cools by reflecting sunlight and radiating heat to outer space through a specific infrared band; the phase change cooling mode stores or releases cold energy through the phase change process of the phase change material;

[0034] When the difference between the frozen soil temperature and the safety temperature is less than the temperature difference threshold, the temperature of the frozen soil road is controlled by the radiation heat dissipation mode; when the difference between the frozen soil temperature and the safety temperature is greater than the temperature difference threshold and the frozen soil temperature is higher than the phase change material temperature, the temperature of the frozen soil road is controlled by the phase change cooling mode; the safety temperature refers to the temperature at which the frozen soil layer can be stable and not freeze-thaw;

[0035] The specific steps of the phase change cooling mode are: determining the temperature difference adjustment amount according to the difference between the frozen soil temperature and the safety temperature, inputting the temperature difference adjustment amount and the corresponding frozen soil temperature, phase change material temperature, soil parameters and phase change material parameters into a flow rate prediction model to obtain a phase change material flow rate prediction value, and adjusting the phase change material flow rate of the active temperature control system of the frozen soil road to actively cool.

[0036] In a second aspect, the active temperature control system of the frozen soil road based on radiation cooling and phase change energy storage comprises:

[0037] An intelligent control module: used to obtain the frozen soil temperature and the phase change material temperature, determine the system operating mode and the temperature difference adjustment amount according to the frozen soil temperature and the safety temperature, input the temperature difference adjustment amount into a flow rate prediction model to obtain a phase change material flow rate prediction value, and send a flow rate control signal;

[0038] A radiation cooling module: performs a radiation heat dissipation mode through a radiation cooling plate heat exchanger; the radiation cooling plate heat exchanger is composed of a radiation cooling coating; the radiation cooling coating adopts a composite polymer base material; the surface of the radiation cooling coating is covered with a hydrophobic protective layer;

[0039] A phase change cooling module: performs a phase change cooling mode through a phase change energy storage circulating device; the phase change energy storage circulating device comprises a sealed pipeline and a circulating pump; the sealed pipeline is filled with a phase change energy storage material; the circulating pump controls the flow rate of the phase change material according to the flow rate control signal and directs the phase change material to be delivered to a heat exchange pipe network module.

[0040] Heat pipe network module: connecting the circulating pump and the sealed pipeline through the heat pipe network, uniformly transferring the phase change material delivered by the circulating pump to the underground frozen soil layer for cooling, and returning the phase change material to the sealed pipeline for cold storage; the heat pipe network is buried in the frozen soil layer and is composed of high-thermal-conductivity metal pipelines; the surface of the high-thermal-conductivity metal pipeline is designed as a porous fin structure;

[0041] Power module: composed of a photovoltaic panel and an energy storage battery, providing continuous power for the phase change energy storage circulating device, the radiation cooling panel heat exchanger and the controller.

[0042] The beneficial effects of the present application are:

[0043] Compared with the prior art, the present application has the following technical effects:

[0044] The present application breaks through the limitation of traditional heat rods in single-season heat dissipation, expands the cold coverage area through the plate structure, determines the system operation mode (radiation of heat to outer space and storage-release cycle of phase change material) by real-time comparison of the temperature difference between the frozen soil layer and the phase change material through intelligent regulation and control, and dynamically adjusts the circulating pump power to realize active regulation of cold throughout the year and prevent heat from being transmitted in reverse; the frozen soil can be long-acting and stable without external power supply through the solar power supply device, which significantly prolongs the service life of the road and reduces the maintenance cost, and can be applied to the temperature control and protection of infrastructure such as railways and oil pipelines in permafrost regions. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The present application is based on the active temperature control method of permafrost road based on radiation cooling and phase change energy storage, and the step flow chart is shown in the figure;

[0046] Figure 2 The present application is based on the active temperature control system of permafrost road based on radiation cooling and phase change energy storage, and the schematic diagram is shown in the figure;

[0047] In the figure: 1-intelligent control device; 2-radiation cooling panel heat exchanger; 3-sealed pipeline; 4-circulating pump; 5 heat pipe network; 6 solar energy supply group. DETAILED DESCRIPTION

[0048] The present application will be further described below through specific examples, and the illustrative examples and explanations of the present application are used to explain the present application, but not as a limitation of the present application.

[0049] The present application is based on the active temperature control method of permafrost road based on radiation cooling and phase change energy storage, and the step flow chart is shown in the figure;

[0050] As shown in Figure 1 In this embodiment, the following steps are included:

[0051] The permafrost region to be regulated is meshed to determine the to-be-determined layout points, the permafrost region characteristics and the highway characteristics of the to-be-determined layout points are obtained to determine a particle search objective function, and the particle search is performed to determine the temperature control layout points and lay out the permafrost highway active temperature control system;

[0052] The permafrost region soil parameters and the phase change material parameters are obtained through laboratory calibration, and the phase change energy storage cycle test is performed at the temperature control layout points to obtain the permafrost temperature change, the phase change material temperature change and the phase change material flow rate change;

[0053] A flow rate prediction model is constructed according to the permafrost temperature change, the phase change material temperature change, the phase change material flow rate change, the soil parameters and the phase change material parameters;

[0054] The system operation mode and the temperature difference adjustment amount are determined according to the actual material temperature difference, the temperature difference adjustment amount is input into the flow rate prediction model to adjust the phase change material flow rate for permafrost highway active temperature control.

[0055] In this embodiment, the method for determining the temperature control layout points comprises:

[0056] The to-be-regulated permafrost region is meshed into 1km×1km grids, the grid vertices with a straight-line distance of less than 500m from the highway are taken as the to-be-determined layout points, and the permafrost region characteristics and the highway characteristics of the to-be-determined layout points are obtained; the permafrost region characteristics include thermal stability grade, landform change rate and surface curvature; the highway characteristics include highway curvature, corner, width and disease point;

[0057] The particle search objective function is determined according to the permafrost region characteristics and the highway characteristics of the to-be-determined layout points, and the expression is:

[0058] J(P)=α1·F cost +α2·F overlap -α3·F cover +α4·F risk

[0059]

[0060]

[0061] Wherein J(P) is the particle search objective function, α1, α2, α3, α4 are search objective weights, F cost is the layout cost function, N set is the number of temperature control layout points, w1, w2 are construction cost weight coefficients, is the landform change rate of the temperature control layout point i, C i is the surface curvature of the temperature control layout point i, F overlap is the range overlap function, Aij F is the area of the overlap of the action circle of temperature control point i and j cover R is the coverage function risk P is the set of temperature control points of the risk section k Ω is the section range of disease risk of the temperature control point k k S is the range of the action circle of the temperature control point k, I(·) is the indicator function (1 if covered, otherwise 0) i D is the permafrost thermal stability grade of the temperature control point i i R is the historical disease mark of the temperature control point i i R is the curvature radius of the highway

[0062] The to-be-determined deployment point is defined as a particle population, and the particle population is chaotically initialized, and the expression is:

[0063]

[0064] wherein is the output value of the primary chaotic mapping at the tth iteration, is the output value of the secondary chaotic mapping at the tth iteration, x t is the final output chaotic value, μ1=0.9+0.1sin(2πt / T) is a dynamic chaotic factor, T is the maximum number of iterations, b1, b2, and b3 are fractal function complexity parameters, is the slope correlation sharpening coefficient, is the absolute value of the rate of change of the permafrost region,

[0065] The particle position is updated The particle position is subjected to Gaussian disturbance to obtain the disturbed particle position The expression is:

[0066]

[0067]

[0068] wherein is the updated position of particle i at the t+1th iteration, w or is the inertia weight, η t =(1+t) -1 is the step factor, is the Levy operator, Γ(·) is the space-time modulation function, is the position change amount of particle i at the tth iteration, γ1=2-e -t / T is the adaptive stability index, γ2=-0.5S z is the permafrost correlation skewness, S z is the permafrost characteristic index, is a curvature-related scale, is a topographic change rate of the particle i to the undetermined layout point, and q is an integral variable, is a global optimal position of t iterations, D max is a maximum distance, and m is a permafrost time window, is a permafrost temperature at τ, is a permafrost temperature mean value, is a permafrost temperature standard deviation, is a phase change material temperature at τ, is a phase change material temperature mean value, is a phase change material temperature standard deviation;

[0069] The particle search target function is calculated by taking the population optimal position as the temperature control layout point, and the temperature control layout point is output when the maximum iteration number is reached or the particle search target function continuously reduces by less than 0.1% for 5 generations, and the permafrost highway active temperature control system is laid according to the temperature control layout point;

[0070] In actual evaluation, in the permafrost region characteristics, the thermal stability level is divided according to the annual average ground temperature of permafrost, wherein, the first level / very stable area (<-5℃), the second level / stable area (-5~-3℃), the third level / substable area (-3~-1℃), and the fourth level / unstable area (>1℃), the topographic change rate is represented by the slope gradient, that is, the elevation change rate per unit distance, and the surface curvature is classified as a valley, a flat land and a slope according to the concave curvature, the zero curvature and the convex curvature;

[0071] The highway parameters at the closest vertical distance of the undetermined layout point are taken as the highway characteristics, the highway curvature is the curvature radius at the curve, the angle is the included angle of adjacent road sections, the width is the highway cross-sectional width, and the disease point is the nearby historical thaw settlement position (1 if there is one, and 0 if there is none);

[0072] The search target weights α1, α2, α3, α4 are respectively taken as 0.3, 0.1, 0.3, 0.3, the construction cost weight coefficients w1, w2 are taken as 0.5, 0.5, the fractal function complexity parameters b1, b2, b3 are respectively taken as 20, 0.7, 7, the inertia weight w or = 0.85, the maximum iteration number is taken as 100, the particle search is performed to determine the temperature control layout point and lay the permafrost highway active temperature control system.

[0073] In the embodiment, the method for constructing the flow rate prediction model comprises:

[0074] The permafrost region soil parameters and the phase change material parameters are obtained through experimental calibration; the soil parameters include water content, soil thermal conductivity, thermal diffusivity and volumetric heat capacity; the phase change material parameters include phase change material specific heat capacity, phase change material thermal conductivity, viscosity and phase change latent heat value;

[0075] The flow rate of the phase change material is adjusted by the active temperature control system of the permafrost highway at the temperature control layout point to obtain corresponding permafrost temperature change and phase change material temperature change, the permafrost temperature change, the phase change material temperature change, the phase change material flow rate, the soil parameters and the phase change material parameters are combined to form a temperature control data set, the temperature control data set is divided into a training set and a test set according to 6:3 by using a random forest algorithm, the training set is used to train a flow rate prediction model, and the test set is used to evaluate the performance of the flow rate prediction model;

[0076] The flow rate prediction model is based on a BP network structure and includes an input layer, a feature branch layer, a feature fusion layer, a hidden layer and an output layer; the feature branch layer outputs soil parameter features, phase change material parameter features and dynamic features through a soil parameter branch, a phase change material branch and a dynamic feature branch; the feature fusion layer cross-fuses the outputs of the feature branch layer to obtain fusion features; the hidden layer is used to capture the dynamic dependency relationship between the fusion features, the phase change material flow rate and the permafrost temperature change, and predict the phase change material flow rate according to the permafrost temperature to be reduced;

[0077] The flow rate prediction model uses a composite loss function to evaluate the difference between the predicted value and the actual value of the phase change material flow rate, and the expression is:

[0078]

[0079] wherein is a composite loss function, is a mean square error loss, λ1 and λ2 are loss weight coefficients, N is the number of samples, ReLU(·) is a ReLU activation function, q actual is an actual heat flux, which is determined by the phase change material flow rate, density, specific heat capacity and temperature difference, q max is a maximum allowable heat flux, which is determined by the thermal conductivity, heat exchange area and permafrost thickness, and ∈ is a safety threshold, is a derivative of the predicted flow rate v i at time t pred , Δt is a time step, is a flow rate change at time step i+1;

[0080] In actual evaluation, in the feature branch layer, the soil parameter branch (4→6 nodes, using the ReLU function) processes the soil parameters to obtain soil parameter features, the phase change material branch (4→6 nodes, using the tanh function) processes the phase change material parameters to obtain phase change material parameter features, and the dynamic feature branch (2→4 nodes, using the ReLU function) processes the phase change material flow rate and the permafrost temperature change to obtain dynamic features; the feature fusion layer (16→12 nodes, using the sigmod function) cross-fuses the soil parameter features, the phase change material parameter features and the dynamic features to obtain fusion features;

[0081] In the composite loss function, the actual heat flux q actual = v * p * c p * ΔT, v, p, c p , ΔT are the flow rate, density, specific heat capacity and temperature difference of the phase change material, respectively, and the maximum allowable heat flux k s , A, δ are the thermal conductivity, heat exchange area and frozen soil thickness, respectively.

[0082] In this embodiment, the method for actively controlling the temperature of the frozen soil road comprises:

[0083] determining the system operation mode and the temperature difference adjustment amount according to the frozen soil temperature and the safety temperature; the operation mode comprises a radiation heat dissipation mode and a phase change cooling mode; the radiation heat dissipation mode continuously cools down by reflecting sunlight and radiating heat to outer space through a specific infrared band; the phase change cooling mode stores or releases cold energy through the phase change process of the phase change material;

[0084] controlling the temperature of the frozen soil road through the radiation heat dissipation mode when the difference between the frozen soil temperature and the safety temperature is less than the temperature difference threshold, and controlling the temperature of the frozen soil road through the phase change cooling mode when the difference between the frozen soil temperature and the safety temperature is greater than the temperature difference threshold and the frozen soil temperature is higher than the phase change material temperature; the safety temperature refers to the temperature at which the frozen soil layer can be stable and not freeze-thaw;

[0085] The specific steps of the phase change cooling mode are: determining the temperature difference adjustment amount according to the difference between the frozen soil temperature and the safety temperature, inputting the temperature difference adjustment amount and the corresponding frozen soil temperature, phase change material temperature, soil parameters and phase change material parameters into a flow rate prediction model to obtain a phase change material flow rate prediction value, and adjusting the phase change material flow rate of the frozen soil road active temperature control system for active cooling;

[0086] In the actual evaluation, taking the determination of the system operation mode as an example, the frozen soil temperatures of the frozen soil road active temperature control systems at positions A and B are-0.82℃ and 0.11℃, respectively, the safety temperature of the frozen soil area is-1℃, the temperature difference threshold is 0.5℃, the frozen soil road active temperature control system at position A adopts the radiation heat dissipation mode to control the temperature of the frozen soil road, and the frozen soil road active temperature control system at position B adopts the phase change cooling mode to control the temperature of the frozen soil road;

[0087] The specific steps of the phase change cooling mode of the frozen soil road active temperature control system at position B are: calculating the difference between the frozen soil temperature and the safety temperature as 1.11℃, taking 0.8*1.11=0.888℃ as the temperature difference adjustment amount, inputting the temperature difference adjustment amount and the corresponding frozen soil temperature, phase change material temperature, soil parameters and phase change material parameters of the frozen soil road active temperature control system at position B into a flow rate prediction model to obtain a phase change material flow rate prediction value, and adjusting the phase change material flow rate of the frozen soil road active temperature control system for active cooling.

[0088] As Figure 2 shown in the present embodiment, the active temperature control system of frozen soil highway based on radiative cooling and phase change energy storage includes: an intelligent control device 1, a radiative cooling plate heat exchanger 2, a sealed pipeline 3, a circulating pump 4, a heat exchange pipe network 5 and a solar energy supply group 6;

[0089] In the actual evaluation, the intelligent control module obtains the frozen soil temperature and the phase change material temperature through the intelligent control device 1 (integrated in the ground protection box, including a temperature sensor and a self-adaptive control unit), determines the system operation mode and the temperature difference adjustment amount according to the frozen soil temperature and the safety temperature, inputs the temperature difference adjustment amount into the flow rate prediction model to obtain the phase change material flow rate prediction value, and sends a flow rate control signal;

[0090] The radiative cooling module performs a radiative cooling mode through the system surface part radiative cooling plate heat exchanger 2; the radiative cooling plate heat exchanger is composed of a radiative cooling coating; the radiative cooling coating reflects sunlight and radiates heat to space through a specific infrared wave band, realizing continuous heat dissipation day and night; the surface of the radiative cooling coating is covered with a hydrophobic protective layer to reduce the influence of snow accumulation or pollutants on the heat dissipation efficiency;

[0091] The phase change cooling module performs a phase change cooling mode through a phase change energy storage circulating device; the phase change energy storage circulating device includes a sealed pipeline 3 and a circulating pump 4; the sealed pipeline is filled with phase change energy storage materials (the phase change liquid flowing in the pipeline is a mixed solution of low-temperature phase change materials and antifreeze); the circulating pump controls the flow rate of the phase change materials according to the flow rate control signal (when the frozen soil layer temperature rises, the intelligent control device triggers the circulating pump to drive the phase change liquid to flow from the radiative cooling plate to the underground pipe network, and when the temperature difference disappears or reverses, the circulating pump automatically stops to prevent heat from being conducted to the frozen soil in the opposite direction), and the phase change materials are directionally delivered to the heat exchange pipe network module;

[0092] The radiative cooling plate heat exchanger 2 and the sealed pipeline 3 form a composite structure, wherein the inner layer is the sealed pipeline 3, the sealed pipeline 3 is filled with low-temperature phase change energy storage materials, stores cold in winter through the solid-liquid phase change process and releases in summer, and the outer layer is the radiative cooling plate heat exchanger 2 (radiative cooling coating), the outer side of the radiative cooling coating is covered with a hydrophobic protective layer to prevent rain and snow or pollutants from reducing the radiative efficiency;

[0093] The heat exchange network module connects the circulation pump 4 and the sealed pipe 3 through the heat exchange network 5, evenly transferring the phase change material transported by the circulation pump to the underground permafrost layer through the heat exchange network 5, and then transferring the phase change material back to the sealed pipe 3, where the radiation cooling plate heat exchanger 2 efficiently dissipates heat and quickly solidifies the phase change material to store cold, while also absorbing excess cold energy from the permafrost. The heat exchange network is buried in the permafrost layer and is composed of high-thermal conductivity metal pipes. The surface of the high-thermal conductivity metal pipes is designed with a porous fin structure to increase the contact area with the permafrost. The pipe network extends horizontally along the highway subgrade, suppressing the thawing and settlement of the permafrost through evenly distributed cold energy transfer. Its flexible connection design can adapt to seasonal deformation of the permafrost and avoid structural fracture.

[0094] The solar energy supply group 6, consisting of photovoltaic panels and energy storage batteries, is installed on top of the radiant cooling panels and provides continuous power to the intelligent control device 1, the radiant cooling plate heat exchanger 2, and the circulation pump 4. The photovoltaic panels are coated with an anti-UV coating, and the energy storage batteries use low-temperature resistant packaging technology to ensure continuous operation of the system in the extreme climate of the plateau.

[0095] The active temperature control system for frozen soil roads based on radiative cooling and phase change energy storage adopts a modular assembly design. The radiative cooling plate 2 is connected to the heat exchange pipe network 5 by a quick-release joint, which is convenient for rapid deployment and maintenance in uninhabited areas of the plateau; the sealed pipe 3 adopts a double-layer leak-proof packaging technology, with the outer layer being a corrosion-resistant alloy and the inner layer being a polymer isolation membrane to ensure long-term operational reliability. During the winter nights, the radiative cooling plate 2 rapidly solidifies the phase change material through efficient heat dissipation to store cold, while absorbing excess cold from the frozen soil. During the summer daytime, the phase change material absorbs underground heat and melts. Combined with the continuous heat dissipation of the radiative cooling plate 2, the temperature rise is delayed, forming a dynamic balance of cold throughout the year, effectively maintaining the stability of the frozen soil.

[0096] 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 in the scope of protection of the present invention.

Claims

1. An active temperature control method for frozen soil roads based on radiative cooling and phase change energy storage, characterized in that: The following steps are involved: S1. Gridding the frozen soil area to be controlled to determine the pending deployment points, obtaining the frozen soil area characteristics and highway characteristics of the pending deployment points to determine the particle search objective function, performing particle search to determine the temperature control deployment points and deploying the frozen soil highway active temperature control system; S2. Obtain soil parameters and phase change material parameters in the frozen soil area through laboratory calibration, and conduct phase change energy storage cycle tests at temperature control points to obtain changes in frozen soil temperature, phase change material temperature, and phase change material flow rate; S3, constructing a flow rate prediction model according to the frozen soil temperature change, the phase change material temperature change, the phase change material flow rate change, the soil parameters and the phase change material parameters; S4. Determine the system operation mode and temperature difference adjustment amount according to the actual material temperature difference, input the temperature difference adjustment amount into the flow rate prediction model to adjust the phase change material flow rate to perform active temperature control on the frozen soil road.

2. The active temperature control method for frozen soil roads based on radiative cooling and phase change energy storage according to claim 1 is characterized in that: The method for determining the temperature control layout points includes: The permafrost area to be controlled is divided into 1km×1km grids. Grid vertices with a straight-line distance of less than 500m from the highway are selected as potential deployment points. The permafrost area characteristics and highway characteristics of the potential deployment points are obtained. The permafrost area characteristics include thermal stability level, landform change rate, and surface curvature. The highway characteristics include highway curvature, corners, width, and disease points. The particle search objective function is determined based on the characteristics of the frozen soil area and the road characteristics of the pending deployment points. The expression is: J(P)=α1·F cost +α2·F overlap -α3·F cover +α4·F risk Where J(P) is the particle search objective function, α1, α2, α3, α4 are the search target weights, and F cost is the layout cost function, N set is the number of temperature control points, w1 and w2 are construction cost weight coefficients, is the landform change rate of temperature control point i, C i is the surface curvature of the temperature control point i, F overlap is the overlap function of the scope of action, A ij is the overlapping area of ​​the action circle of temperature control point i and j, F cover is the coverage function, R risk is the set of temperature control points on the risky road section, P k is the road section range with disease risk at point k, Ω k is the action circle range of the layout point k, I(·) is the indicator function (takes 1 if coverage, otherwise takes 0), S i is the thermal stability grade of frozen soil at temperature control point i, D i For temperature control layout point i historical disease mark, R i is the road curvature radius; The undetermined deployment points are defined as particle populations, and the particle populations are initialized chaotically. The expression is: in is the output value of the primary chaotic map at the tth iteration, is the output value of the secondary chaotic map at the tth iteration, x t is the final chaotic value output, μ1=0.9+0.1sin(2πt / T) is the dynamic chaotic factor, T is the maximum number of iterations, b1, b2, b3 are the fractal function complexity parameters, is the slope-related sharpening coefficient, is the absolute value of the geomorphic change rate in the permafrost region; Update particle position And perform Gaussian perturbation on the particle position to obtain the perturbed particle position The expression is: in is the updated position of particle i in the t+1 iteration, w or is the inertia weight, η t =(1+t) -1 is the step size factor, is the Levy operator, Γ(·) is the spatiotemporal modulation function, is the position change of particle i after t iterations, γ1=2-e -t / T is the adaptive stability index, γ2=-0.5S z is the frozen soil association skewness, S z is an indicator of frozen soil characteristics, is the curvature-related scale, is the landform change rate of particle i corresponding to the undetermined deployment point, q is the integral variable, is the global optimal position of t iterations, D max is the maximum distance, m is the frozen soil time series window, is the frozen soil temperature at time τ, is the mean permafrost temperature, is the standard deviation of frozen ground temperature, is the temperature of the phase change material at time τ, is the average temperature of the phase change material, is the standard deviation of phase change material temperature; The optimal position of the population is used as the temperature control layout point to calculate the particle search objective function. The temperature control layout point is output when the maximum number of iterations is reached or the particle search objective function decreases by less than 0.1% for five consecutive generations. The active temperature control system for frozen soil roads is deployed according to the temperature control layout point.

3. The active temperature control method for frozen soil roads based on radiative cooling and phase change energy storage according to claim 1 is characterized in that: The method for constructing a flow velocity prediction model comprises: The soil parameters and phase change material parameters of the frozen soil area are obtained through experimental calibration; the soil parameters include moisture content, soil thermal conductivity, thermal diffusivity and volume heat capacity; the phase change material parameters include phase change material specific heat capacity, phase change material thermal conductivity, viscosity and phase change latent heat value; An active temperature control system for frozen soil roads was deployed at the temperature control points to adjust the phase change material flow rate to obtain the corresponding frozen soil temperature changes and phase change material temperature changes. The frozen soil temperature changes, phase change material temperature changes, phase change material flow rate, soil parameters, and phase change material parameters were combined into a temperature control dataset. The temperature control dataset was divided into a training set and a test set in a ratio of 6:3 using a random forest algorithm. The training set was used to train the flow rate prediction model, and the test set was used to evaluate the flow rate prediction model's performance. The flow rate prediction model is based on a BP network structure and includes an input layer, a feature branch layer, a feature fusion layer, a hidden layer, and an output layer. The feature branch layer outputs soil parameter features, phase change material parameter features, and dynamic features through soil parameter branches, phase change material branches, and dynamic feature branches. The feature fusion layer cross-fuses the outputs of the feature branch layer to obtain fusion features. The hidden layer is used to capture the dynamic dependency between the fusion features, the phase change material flow rate, and the frozen soil temperature change, and predict the phase change material flow rate based on the desired reduction in frozen soil temperature. The flow rate prediction model uses a composite loss function to evaluate the difference between the predicted value and the actual value of the phase change material flow rate, which is expressed as: in is the composite loss function, is the mean square error loss, λ1 and λ2 are loss weight coefficients, N is the number of samples, ReLU(·) is the ReLU activation function, and q actual is the actual heat flux, which is determined by the phase change material flow rate, density, specific heat capacity and temperature difference, q max is the maximum allowable heat flux, which is determined by the thermal conductivity, heat transfer area and frozen soil thickness, ∈ is the safety threshold, is time t i Predicted flow velocity v pred The derivative of , Δt is the time step, is the flow velocity change at time step i+1.

4. The active temperature control method for frozen soil roads based on radiative cooling and phase change energy storage according to claim 1 is characterized in that: The method for active temperature control of frozen soil roads comprises: The system operation mode and temperature difference adjustment amount are determined based on the permafrost temperature and the safety temperature. The operation modes include radiation heat dissipation mode and phase change cooling mode. The radiation heat dissipation mode continuously cools the system by reflecting sunlight and radiating heat to outer space through a specific infrared band. The phase change cooling mode stores or releases cold energy through the phase change process of phase change materials. When the difference between the frozen soil temperature and the safe temperature is less than the temperature difference threshold, the temperature of the frozen soil road is controlled by the radiation heat dissipation mode. When the difference between the frozen soil temperature and the safe temperature is greater than the temperature difference threshold and the frozen soil temperature is higher than the phase change material temperature, the temperature of the frozen soil road is controlled by the phase change cooling mode. The safe temperature refers to the temperature at which the frozen soil layer can be stable without freezing and thawing. The specific steps of the phase change cooling mode are: determining the temperature difference adjustment amount according to the difference between the frozen soil temperature and the safety temperature, inputting the temperature difference adjustment amount and the corresponding frozen soil temperature, phase change material temperature, soil parameters and phase change material parameters into the flow rate prediction model to obtain the phase change material flow rate prediction value, and adjusting the phase change material flow rate of the frozen soil highway active temperature control system for active cooling.

5. An active temperature control system for frozen soil roads based on radiative cooling and phase change energy storage, for executing the method according to any one of claims 1 to 4, comprising: Intelligent control module: used to obtain the temperature of frozen soil and phase change material, determine the system operation mode and temperature difference adjustment amount according to the frozen soil temperature and safety temperature, input the temperature difference adjustment amount into the flow rate prediction model to obtain the phase change material flow rate prediction value, and issue a flow rate control signal; Radiative cooling module: Radiative cooling plate heat exchanger performs radiative heat dissipation mode; the radiative cooling plate heat exchanger is composed of a radiative cooling coating; the radiative cooling coating is made of a composite polymer-based material; the surface of the radiative cooling coating is covered with a hydrophobic protective layer; Phase change refrigeration module: executes phase change cooling mode through a phase change energy storage circulation device; the phase change energy storage circulation device includes a sealed pipe and a circulation pump; the sealed pipe is filled with phase change energy storage material; the circulation pump controls the flow rate of the phase change material according to the flow rate control signal, and directionally transports the phase change material to the heat exchange pipe network module; Heat exchange network module: The heat exchange network connects the circulation pump and the sealed pipe, evenly transfers the phase change material delivered by the circulation pump to the underground frozen soil layer for cooling, and then transfers the phase change material back to the sealed pipe for cold storage; The heat exchange pipe network is buried in the frozen soil layer and is composed of high thermal conductivity metal pipes; the surface of the high thermal conductivity metal pipes is designed to have a porous fin structure; Power module: Consists of photovoltaic panels and energy storage batteries, providing continuous power for the phase change energy storage cycle device, radiant cooling plate heat exchanger and controller.

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