A frozen method construction cold adaptive supply method

Abstract

The application discloses a frozen construction cold adaptive supply method, which comprises the following steps: firstly, obtaining the real-time temperature field and the measured soil parameters at t0 time of the cold supply area to obtain the predicted heat load value at t1 time of the cold supply area; secondly, obtaining the theoretical brine flow value capable of completely removing the predicted total heat load value according to the predicted total heat load value and in combination with a given target temperature rise value; thirdly, obtaining the theoretical optimal brine flow value by using an optimization calculation model and sending the theoretical optimal brine flow value to a terminal execution device for execution. The application adopts the adjustment mode of 'advance prediction of heat load-advance calculation of brine flow-optimization of brine flow-real-time regulation and control', supplies cold in real time according to the needs to the corresponding area, continuously optimizes the brine flow calculated in advance on the basis of real-time parameters under the premise of ensuring the freezing effect, and makes the energy consumption of the freezing unit volume of soil minimum.

Description

Technical Field

[0001] This invention relates to the field of underground engineering freezing construction technology. Specifically, it is a method for adaptive supply of cooling capacity during freezing construction. Background Technology

[0002] In current freezing method construction, the cold load control mainly adopts the "constant flow" or "manual experience adjustment" mode. Regardless of whether the ground freezing wall has been formed, it often operates at full load. When the freezing wall reaches the design thickness, in order to ensure safety, it continues to deliver excessive cold load, resulting in energy waste. When there is a sudden change in local heat load, the response is lagging and it is difficult to quickly deal with and resolve the sudden change in heat load. Summary of the Invention

[0003] Therefore, the technical problem to be solved by this invention is to provide an adaptive cold supply method for freezing construction. Based on real-time temperature field and soil parameters, the method predicts the temperature field and total heat load value at future moments to obtain the predicted brine flow rate value. Through an optimization calculation model, the brine flow rate value is optimized in real time and the current brine flow rate is adjusted to achieve adaptive cold supply control. Compared with the traditional mode of "detecting heat load mutation - adjusting brine flow rate - re-checking heat load - optimizing brine flow rate", this method achieves real-time and proactive brine flow rate control, no longer relying on manual experience, and has the advantages of proactive response, suppression of mutation and rapid resolution when dealing with heat load mutations.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for adaptive cold supply during freezing construction, comprising the following steps:

[0005] Step 1: Obtain the real-time temperature field and measured soil parameters of the cooling area at time t0. Solve the predicted temperature field and predicted heat load value of the cooling area at time t1 using the three-dimensional temperature field model and the total heat load calculation formula. Here, time t0 is the current time and time t1 is the next time after time t0.

[0006] Step 2: Based on the predicted total heat load value and the given target temperature rise value, use the formula for the relationship between flow rate and temperature difference to back-calculate the theoretical brine flow rate that can completely remove the predicted total heat load value.

[0007] Step 3: Calculate the cumulative electrical energy consumption of relevant equipment during the interval from t0 to t1 when running at the theoretical brine flow rate; obtain the effective frozen volume that has reached the design temperature requirement at t1 based on the predicted temperature field integral at t1; construct a unit volume energy consumption ratio optimization model using the ratio of cumulative electrical energy consumption to effective frozen volume; optimize the theoretical brine flow rate value through the optimization model to obtain the theoretical optimal brine flow rate value that matches the predicted heat load value at t1.

[0008] Step 4: Convert the theoretical optimal brine flow rate into actual control commands and send them to the terminal execution device for execution, thereby adjusting the brine flow rate in real time;

[0009] Step 5: The sensor collects the latest on-site operating data in real time, and executes steps 1 to 4 in a loop based on the updated measured data to achieve continuous dynamic adaptive control of brine flow.

[0010] In the above-mentioned adaptive supply method for cooling capacity during freezing construction, in step 1, a three-dimensional temperature field model is imported using real-time temperature field and measured soil parameters as input conditions. Based on the three-dimensional temperature field model, the predicted temperature field of the soil in the cooling area at time t1 is calculated and deduced using a time series prediction algorithm. The predicted temperature field is then verified using the real-time temperature field, and the ice volume fraction of the soil in the cooling area at time t1 is calculated. Finally, the temperature change rate and the ice volume fraction change rate are obtained using the time difference method.

[0011] The three-dimensional temperature field model for the adaptive cold supply method in the above-mentioned freezing construction is as follows:

[0012]

[0013] in: This refers to the total density of the soil, expressed in kg / m³. Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of soil by 1°C, expressed in J / (kg·K). Temperature at a point in space at a specific moment, expressed in Kelvin (K). The time coordinates for the freezing process are in seconds. The rate of temperature change represents how quickly the temperature at a point changes over time. Thermal conductivity is the ability of a material to conduct heat, expressed in W / (m·K). For the Laplace operator, represents the sum of the second-order partial derivatives of temperature in three-dimensional space; The latent heat of phase change is the heat released by a unit mass of water during the freezing process, or the heat absorbed by a unit mass of ice during the melting process, expressed in J / kg. This is the density of ice, expressed in kg / m³. is the ice volume fraction, which is the proportion of the volume occupied by ice in the soil pores. It is dimensionless and ranges from 0 to 1, where 0 indicates that the water in the soil pores is completely unfrozen and 1 indicates that the pores are completely filled with ice. The rate of change of ice volume fraction represents the rate at which the ice content changes within 1 second.

[0014] In the above-mentioned adaptive supply method for cooling capacity during freezing construction, in step 1, the temperature change rate, ice volume fraction, and ice volume fraction change rate at time t1 are imported into the total heat load calculation formula to obtain the predicted total heat load that needs to be removed from the cooling area at time t1.

[0015] The formula for calculating the total heat load using the above-mentioned adaptive cooling supply method for freezing construction is as follows:

[0016]

[0017] in: Total heat load, representing the heat flow that the freezing system needs to remove from the ground in the cooling area at time t1, in W; The total rate of change of sensible heat in the soil over the entire cooling area is expressed as an integral over the entire cooling area, in meters. 3 ; The sensible heat change rate per unit volume of soil represents the rate at which a unit volume of soil absorbs or releases heat due to temperature change per unit time, with units of W / m³. 3 ; The rate of temperature change represents how quickly the temperature at a point changes over time. The total rate of latent heat release from the phase change of ice and water within the phase change region is expressed as the integral over the volume of the cooling area where the phase change is taking place, i.e., the region with a temperature near the freezing point, and is measured in meters (m³). 3 ; The latent heat release rate of phase change per unit volume represents the heat flow released per unit volume when water freezes into ice, with units of W / m³. 3 ; The heat flow entering from outside the region boundary represents the integral over the entire outer surface of the cooling area, in m². Heat flux density, representing the heat flow from the unfrozen area of ​​the external environment and groundwater into the frozen area through the boundary, calculated based on the geothermal gradient and Darcy's law, is expressed in W / m². Surface area, the interface area between the refrigerated area and the unfrozen external area, in m².

[0018] In the above-mentioned adaptive cold supply method for freezing construction, step 2, the formula relating flow rate and temperature difference is:

[0019]

[0020] in: The target temperature rise is represented by the temperature rise at a given predicted total heat load. To ensure heat balance in the monitoring area, the temperature that the brine should rise when it flows through the freezing pipe and is discharged is measured in °C. The predicted total heat load is the average heat load forecast value for a future period of time, calculated from the total heat load calculation formula, and is expressed in W. This represents the theoretical brine flow rate to be determined, in kg / s. is the specific heat capacity of brine, expressed in J / (kg·K).

[0021] In the above-mentioned adaptive cold supply method for freezing construction, step 3, the formula for calculating the effective frozen volume at time t1 is:

[0022]

[0023] in: The effective volume of frozen soil at time t, in meters. 3 ; This represents the volume integral performed over any location (x, y, z) where the temperature is below a set threshold within the entire three-dimensional space.

[0024] In the above-mentioned adaptive cold supply method for freezing construction, the statistical formula for cumulative electrical energy consumption in step 3 is as follows:

[0025]

[0026] in: Cumulative energy consumption, in kWh; The instantaneous total power input to the relevant equipment, in kW; This represents the cumulative power consumption of all devices related to freezing from time t0 to time t1.

[0027] The adaptive cold supply method for the above-mentioned freezing construction, the optimization calculation model in step 3 is as follows:

[0028]

[0029] in: The objective function value represents the electrical energy consumed to form one cubic meter of effective permafrost, expressed in kWh / m³. Cumulative energy consumption, in kWh; For effective frozen volume, the unit is m. 3 .

[0030] The above-mentioned adaptive cooling supply method for freezing construction involves dividing the freezing construction area into three or more cooling zones along the circumference on a horizontal plane. Any two cooling zones are adjacent to each other. Each cooling zone has an independent freezing pipe group installed along the depth of the stratum. Each freezing pipe group controls the brine flow rate individually through a terminal actuator. When a sudden change in heat load occurs in any cooling zone, the brine flow rate of the cooling zone experiencing the heat load change and the brine flow rate of the two adjacent cooling zones are controlled separately through the terminal actuator.

[0031] The technical solution of the present invention achieves the following beneficial technical effects:

[0032] This invention employs a regulation method of "advanced prediction of heat load - advanced calculation of brine flow - optimization of brine flow - real-time control" to supply cooling capacity to the corresponding area in real time on demand. While ensuring the freezing effect, the pre-calculated brine flow is continuously optimized based on real-time parameters, so that the energy consumed in freezing a unit volume of soil is minimized. Compared with traditional constant flow operation or manual experience operation, the cooling capacity supply is more precise, and can save 15%-25% of electricity while ensuring safety.

[0033] This invention, based on the advanced prediction and calculation of brine flow rate and real-time optimization, responds in advance to changes in heat load and effectively controls the stability of the frozen wall.

[0034] This invention utilizes temperature measuring holes pre-embedded in the soil layer to obtain real-time temperature fields that completely cover the entire cooling area. The cooling area is treated as a whole for dynamic optimization of cooling, realizing the transition from point control to field control for a single cooling area, effectively preventing the frozen soil wall from becoming too thin. For the entire frozen wall, by dividing it into multiple cooling areas, when the heat load of a single cooling area changes abruptly, the cooling capacity of each cooling area can be adjusted separately to limit the expansion of the area of ​​heat load change, avoiding affecting the stability of the entire or large-area frozen wall. The stability of the entire frozen wall is maintained by the independent control of each cooling area. Attached Figure Description

[0035] Figure 1 Flowchart of the adaptive cooling capacity supply method of the present invention;

[0036] Figure 2 A schematic diagram showing multiple adjacent cooling zones in this invention.

[0037] The attached diagram is labeled as follows: 1-Cooling area; 2-Freezing pipe assembly. Detailed Implementation

[0038] This embodiment presents an adaptive cold supply method for freezing construction. For vertical shafts, the shaft wall is the area requiring cold supply. A freezing pipe assembly 2 is installed within the shaft wall, and low-temperature brine is circulated within the assembly to supply cold to the shaft wall. To enable monitoring, the same sensors used in conventional construction are employed. Flow sensors and temperature sensors are installed on the brine circulation pipeline of the freezing pipe assembly 2 to accurately measure the real-time brine flow rate, supply temperature, and return temperature of each loop.

[0039] Temperature measurement holes are designed into the well wall as needed. Using single-bus technology, digital temperature sensors are placed in the temperature measurement holes and freezing holes to build a highly reliable long-distance single-bus temperature measurement network. The digital temperature sensors specifically use the improved DS18B20 or equivalent single-bus protocol chip, with a temperature measurement range of -40℃ to +85℃ and an accuracy of ±0.5℃. Twisted-pair shielded cables are used as the transmission medium. The position and number of measurement points are arranged along the axis of each temperature measurement hole and freezing hole according to actual needs. Before leaving the factory, each digital temperature sensor is uniquely coded with a 64-bit ROM address, and a "hole number-depth-address" mapping table is established. The basic acquisition cycle is set, with a default of 1 second / piece / time.

[0040] The specific construction process includes the following steps:

[0041] Step 1: Obtain the real-time temperature field and measured soil parameters of the cooling area. After the host computer collects the raw temperature data of each digital temperature sensor, it performs data cleaning and interpolation compensation. Data with a single reading jump of more than 5°C and no change in adjacent points are regarded as abrupt noise points and are removed to achieve data cleaning. When one of the digital temperature sensors fails and goes offline, the temperature values ​​of the adjacent normal sensors are used to generate virtual temperature values ​​using linear interpolation or cubic spline interpolation to ensure the integrity of the data chain. Combine the measured data of each digital temperature sensor in the cooling area to construct the real-time temperature field of the soil around the well at time t0.

[0042] The measured soil parameters include the total density, specific heat capacity, thermal conductivity, water content, and porosity of the soil obtained through exploration, which are used to support actual calculations;

[0043] The real-time temperature field and measured soil parameters are used as input conditions to import into the three-dimensional temperature field model. Based on the three-dimensional temperature field model, the predicted temperature field of the soil in the cooling area at time t1 is calculated and derived using a time series prediction algorithm. The predicted temperature field is verified using the real-time temperature field, and the ice volume fraction of the soil in the cooling area at time t1 is calculated. The temperature change rate and the ice volume fraction change rate are obtained using the time difference method. Time t1 is the next time after time t0.

[0044] The three-dimensional temperature field model is as follows:

[0045]

[0046] in: This refers to the total density of the soil, expressed in kg / m³. Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of soil by 1°C, expressed in J / (kg·K).

[0047] Temperature at a point in space at a specific moment, expressed in Kelvin (K). The time coordinates for the freezing process are in seconds.

[0048] The rate of temperature change represents how quickly the temperature at a point changes over time.

[0049] W is the thermal conductivity, which represents the ability of a material to conduct heat. The unit is W / (m·K). The thermal conductivity of ice is approximately 2.22 W / (m·K).

[0050] Let be the Laplace operator, representing the sum of the second-order partial derivatives of temperature in three-dimensional space. Alternatively, it can be used To represent, that is ;

[0051] The latent heat of phase change is the heat released per unit mass of water during freezing, or the heat absorbed per unit mass of ice during melting; it is measured in J / kg. The latent heat of freezing of water is approximately 334 kJ / kg. This is the largest source of heat load in freezing engineering.

[0052] This is the density of ice, expressed in kg / m³.

[0053] is the ice volume fraction, which is the proportion of the volume occupied by ice in the soil pores. It is dimensionless and ranges from 0 to 1, where 0 indicates that the water in the soil pores is completely unfrozen and 1 indicates that the pores are completely filled with ice.

[0054] The rate of change of ice volume fraction represents the rate at which the ice content changes within 1 second.

[0055] Then, using the total heat load calculation formula, the predicted heat load value of the cooling area at time t1 is obtained; the total heat load calculation formula is:

[0056]

[0057] in: The total heat load represents the amount of heat the freezing system needs to remove from the ground in the cooling area at time t1, i.e., the heat dissipation per unit time, expressed in W. This represents the integral over the entire cooling area volume, in meters (m). 3 ; The sensible heat change rate per unit volume of soil represents the rate at which a unit volume of soil absorbs or releases heat due to temperature change per unit time, with units of W / m³. 3 ; The rate of temperature change represents how quickly the temperature at a point changes over time. This represents the integral over the volume of the cooling area where a phase change is occurring, i.e., the region with a temperature near the freezing point, expressed in meters (m). 3 ; The latent heat release rate of phase change per unit volume represents the heat flow released per unit volume when water freezes into ice. It is the main heat source for the expansion of the frozen wall, and its unit is W / m³. 3 ; This represents the integral over the entire outer surface of the cooling area, in m². Heat flux density, representing the heat flow from the unfrozen area of ​​the external environment and groundwater into the frozen area through the boundary, calculated based on the geothermal gradient and Darcy's law, is expressed in W / m². The surface area is the interface area between the cooled area and the unfrozen external area, in m².

[0058] By importing the temperature change rate, ice volume fraction, and ice volume fraction change rate at time t1 into the total heat load calculation formula, the predicted total heat load that needs to be removed from the cooling area at time t1 can be obtained.

[0059] Step 2: Based on the predicted total heat load and the given target temperature rise, use the formula relating flow rate and temperature difference to inversely calculate the theoretical brine flow rate that can completely remove the predicted total heat load. The formula relating flow rate and temperature difference is:

[0060]

[0061] in: The target temperature rise is represented by the temperature rise at a given predicted total heat load. To ensure heat balance in the monitoring area, the temperature that the brine should rise when it flows through the freezing pipe and is discharged is measured in °C. The predicted total heat load is the average heat load forecast value for a future period of time, calculated from the total heat load calculation formula, and is expressed in W. This represents the theoretical brine flow rate to be determined, in kg / s. is the specific heat capacity of brine, expressed in J / (kg·K);

[0062] Calculate the calories carried by the salt water:

[0063]

[0064] in: The actual heat extracted, in W or kW, represents the actual heat that the brine circulation system brings back from the freezing hole at a given flow rate; The mass or volume of brine flowing through the pipeline within a given time interval, expressed in kg / s or m³ / s. The specific heat capacity of brine is given by J / (kg·K). Generally, the specific heat capacity of calcium chloride brine is slightly lower than that of water, and it varies with temperature and concentration. The return temperature (recovery temperature) indicates the temperature of the brine as it returns to the unit from the freezing hole, in °C. The supply water temperature (outgoing route) indicates the temperature of the brine when it enters the freezing hole from the unit, in °C. The temperature rise of brine represents the temperature increase of the brine after absorbing heat from the formation as it flows through the freezing pipe. The greater the temperature difference, the more heat a unit mass of brine brings back. The unit is K or °C.

[0065] Step 3: Based on the theoretical brine flow rate, calculate the cumulative power consumption of the equipment operating at the theoretical brine flow rate from time t0 to t1, and calculate the effective frozen volume that has reached the design temperature requirement at time t1 based on the predicted temperature field at time t1.

[0066] The formula for calculating the effective frozen volume at time t1 is:

[0067]

[0068] in: The effective frozen soil volume at time t1, in meters. 3 ; This represents any point within the entire three-dimensional space region. Volume integration is performed on regions where the temperature is below a set threshold; the threshold is typically set to be below 0°C.

[0069] The steps for calculating the pump power at time t1, based on the theoretical brine flow rate, are as follows:

[0070] Step a: Calculate the theoretical saline flow rate. Substituting the values ​​into the pipeline characteristic curve formula, the total head is calculated using the following formula:

[0071]

[0072] in: Total head, in meters (m); The static head is measured in meters (m). This refers to the pipeline resistance coefficient. The value is the square of the flow rate, expressed in kg / s².

[0073] Step b: Substitute the total head H calculated in step a into the pump shaft power calculation formula to calculate the pump input power. The specific formula is as follows:

[0074]

[0075] in: The input power of the water pump is the electrical power that the motor draws from the power grid, measured in kW. This is the mass flow rate of the brine flowing through the pump, i.e., the theoretical brine flow rate, in kg / s. It is the acceleration due to gravity; Total head, in meters (m); The efficiency of the water pump is dimensionless and ranges from 0 to 1. The efficiency of the motor is dimensionless and ranges from 0 to 1.

[0076] Step c: Input power to the water pump Substituting into the cumulative energy consumption calculation formula, the cumulative energy consumption from the current time t0 to the future time t1 is calculated and obtained. The specific formula is as follows:

[0077]

[0078] in: Cumulative energy consumption, in kWh; The instantaneous total power input to the water pump, in kW; This represents the cumulative electrical energy consumption of the water pump from time t0 to time t1; this embodiment uses a water pump as an example for explanation. Using the water pump input power calculated in step b above, the energy consumption of the refrigeration unit can be further collected and statistically analyzed. Usually, the refrigeration unit itself has an integrated power and energy consumption monitoring and statistical module.

[0079] Based on the ratio of total equipment power to effective frozen volume, an optimization calculation model for energy consumption per unit volume is established; the optimization calculation model is as follows:

[0080]

[0081] in: The objective function value represents the electrical energy consumed to form one cubic meter of effective permafrost, expressed in kWh / m³. Cumulative energy consumption, in kWh; For effective frozen volume, the unit is m. 3 ;

[0082] By optimizing the theoretical brine flow rate using an optimization calculation model, the current "energy consumption ratio per unit volume" is calculated. This ratio is the objective function that the optimization algorithm needs to minimize.

[0083] Using an optimization calculation model, the optimal brine flow rate setting is found while satisfying the freezing effect constraints. Constraints include: clearly defining the standards that the freezing effect must meet, such as "the frozen wall thickness is not less than x meters" or "the average temperature is lower than y℃". Any flow rate adjustment must not violate these safety constraints to ensure the safety of the frozen wall. The optimal solution is found using a hill-climbing method or a genetic algorithm.

[0084] Starting from the current operating state, the algorithm iteratively searches by simulating or predicting the "energy consumption ratio per unit volume" under different flow rate setpoints, and finally finds the theoretical brine flow rate that minimizes the ratio, thus obtaining the theoretically optimal brine flow rate.

[0085] Step 4: The theoretically optimal brine flow rate is converted into actual control commands and sent to the terminal execution device to regulate the brine flow rate. The terminal execution device is the frequency converter or electric regulating valve of the water pump corresponding to cooling zone 1. By changing the operating frequency of the frequency converter or the opening of the electric regulating valve, the flow rate entering cooling zone 1 is ultimately controlled. Traditional control relies solely on brine temperature difference feedback, which cannot predict heat load fluctuations caused by soil phase changes and groundwater seepage, resulting in lag in regulation. This invention is based on global heat load prediction, matching the actual heat load of the stratum, predicting and optimizing the flow rate required at the next moment, reducing supercooling ineffective energy consumption, and achieving an overall power saving of 15%-25%.

[0086] Step 5: After the terminal execution device executes the latest theoretically optimal brine flow rate value, it enters the next operating cycle; using various sensor modules to monitor the latest operating data in real time, and based on the latest operating data, recalculate the energy consumption ratio per unit volume, and repeat the above process periodically to achieve continuous dynamic optimization control.

[0087] Existing static flow supply systems generally suffer from uneven formation heating, insufficient cooling in groundwater areas, and excessive cooling in areas without seepage, resulting in wasted energy. In this embodiment, such as... Figure 2 As shown, the freezing construction area is divided into three or more cooling zones 1 along the circumference on the horizontal plane. Any two cooling zones 1 are set up adjacent to each other. Each cooling zone 1 is equipped with an independent freezing pipe group 2 along the stratum depth direction. Each freezing pipe group 2 is individually controlled by a terminal execution device to regulate the brine flow rate. That is, each freezing pipe group 2 is independently controlled by an independent variable frequency water pump to regulate the brine circulation flow rate.

[0088] In actual construction, heat load changes usually fluctuate regularly and stably based on different construction stages. When a sudden change in heat load occurs, it is usually caused by the emergence of groundwater at a certain point, which manifests as a continuous increase in temperature within a certain range, and the range gradually spreads, showing the characteristics of high temperature at the center and low temperature around the periphery.

[0089] In this implementation, the entire freezing construction area, i.e. the frozen wall of the well, is divided into at least three cooling zones 1, which can promptly detect areas of sudden changes in heat load and provide cooling based on the theoretically optimal brine flow rate.

[0090] In the early stages of a water inrush, the flow velocity at the inrush point is relatively fast, and it slowly diffuses and infiltrates, mainly affecting the temperature of the frozen wall at the inrush point, while the surrounding frozen wall is less affected. When using temperature sensors for detection, the inrush point can usually be detected by obvious temperature changes, while the temperature changes in the area around the inrush point, especially at the edges, are not obvious or even non-existent, making it difficult to accurately determine the inrush area using temperature sensors. This results in the actual infiltration range of groundwater being larger than the monitored range.

[0091] In specific judgment, the host computer obtains the temperature data corresponding to the cooling area 1, and when the temperature distribution characteristics of the area conform to the water inrush characteristics, it judges that the heat load of the cooling area 1 has changed suddenly. When any cooling area 1 experiences a heat load change, the host computer first judges that a heat load change has occurred by using the digital temperature sensor of the cooling area 1, the supply water temperature and the return water temperature, and calculates the theoretical optimal brine flow rate value based on steps 1-4.

[0092] During actual cooling, firstly, based on the theoretical optimal brine flow rate of cooling zone 1 experiencing a sudden change in heat load, the brine flow rate of the two adjacent cooling zones 1 is adjusted. The adjusted brine flow rate is greater than the flow rate before adjustment but less than the theoretical optimal brine flow rate calculated based on cooling zone 1 experiencing a sudden change in heat load. This is used to prevent and seal the two adjacent zones, forming reinforced zones on both sides, preventing groundwater from continuing to diffuse and infiltrate outwards. Since the temperature gradually decreases from the center outwards during groundwater infiltration, the cooling capacity can first freeze the surrounding second-year water, and then gradually freeze inwards, repeating steps 1-4. The temperature of the two cooling zones 1 on both sides is monitored and predicted to maintain the temperature drop of the frozen wall. Based on the theoretical optimal brine flow rate... The brine flow rate of cooling zone 1 experiencing a sudden heat load change is regulated to control water inflow from multiple directions. When the real-time heat load and predicted heat load values ​​of cooling zone 1 experiencing the sudden heat load change stabilize and no longer rise, or gradually decrease, it indicates that the water inflow at that location has been frozen. Subsequently, the brine flow rate of cooling zone 1 experiencing the sudden heat load change is first regulated based on the theoretically optimal brine flow rate value, while the brine flow rates of cooling zones 1 on both sides are maintained at a level higher than the predicted heat load value of that zone. After a certain period of operation, when the real-time heat load and predicted heat load values ​​of cooling zone 1 experiencing the sudden heat load change remain stable, the brine flow rate of all cooling zones 1 is restored to the theoretically optimal brine flow rate value obtained based on the predicted total heat load value of that zone.

[0093] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for adaptive supply of cooling capacity during freezing construction, characterized in that, Includes the following steps: Step 1: Obtain the real-time temperature field and measured soil parameters of the cooling area at time t0. Solve the predicted temperature field and predicted heat load value of the cooling area at time t1 using the three-dimensional temperature field model and the total heat load calculation formula. Here, time t0 is the current time and time t1 is the next time after time t0. Step 2: Based on the predicted total heat load value and the given target temperature rise value, use the formula for the relationship between flow rate and temperature difference to back-calculate the theoretical brine flow rate value for completely removing the predicted total heat load value. Step 3: Calculate the cumulative electrical energy consumption of relevant equipment during the interval from t0 to t1 when running at the theoretical brine flow rate; obtain the effective frozen volume that has reached the design temperature requirement at t1 based on the predicted temperature field integral at t1; construct a unit volume energy consumption ratio optimization model using the ratio of cumulative electrical energy consumption to effective frozen volume; optimize the theoretical brine flow rate value through the optimization model to obtain the theoretical optimal brine flow rate value that matches the predicted heat load value at t1. Step 4: Convert the theoretical optimal brine flow rate into actual control commands and send them to the terminal execution device for execution, thereby adjusting the brine flow rate in real time; Step 5: The sensor collects the latest on-site operating data in real time, and executes steps 1 to 4 in a loop based on the updated measured data to achieve continuous dynamic adaptive control of brine flow.

2. The adaptive cold supply method for freezing construction according to claim 1, characterized in that, In step 1, the real-time temperature field and measured soil parameters are used as input conditions to import the three-dimensional temperature field model. Based on the three-dimensional temperature field model, the predicted temperature field of the soil in the cooling area at time t1 is calculated and derived by combining the time series prediction algorithm. The ice volume fraction of the soil in the cooling area at time t1 is calculated, and the temperature change rate and ice volume fraction change rate are obtained by using the time difference method.

3. The adaptive cold supply method for freezing construction according to claim 2, characterized in that, The three-dimensional temperature field model is as follows: ； in: This refers to the total density of the soil, expressed in kg / m³. Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of soil by 1°C, expressed in J / (kg·K). Temperature at a point in space at a specific moment, expressed in Kelvin (K). The time coordinates for the freezing process are in seconds. The rate of temperature change represents how quickly the temperature at a point changes over time. Thermal conductivity is the ability of a material to conduct heat, expressed in W / (m·K). For the Laplace operator, represents the sum of the second-order partial derivatives of temperature in three-dimensional space; The latent heat of phase change is the heat released by a unit mass of water during the freezing process, or the heat absorbed by a unit mass of ice during the melting process, expressed in J / kg. This represents the density of ice, expressed in kg / m³. is the ice volume fraction, which is the proportion of the volume occupied by ice in the soil pores. It is dimensionless and ranges from 0 to 1, where 0 indicates that the water in the soil pores is completely unfrozen and 1 indicates that the pores are completely filled with ice. The rate of change of ice volume fraction represents the rate at which the ice content changes within 1 second.

4. The adaptive cold supply method for freezing construction according to claim 3, characterized in that, In step 1, the temperature change rate, ice volume fraction, and ice volume fraction change rate at time t1 are imported into the total heat load calculation formula to obtain the predicted total heat load that needs to be removed from the cooling area at time t1.

5. The adaptive cold supply method for freezing construction according to claim 4, characterized in that, The formula for calculating the total heat load is as follows: ； in: Total heat load, representing the heat flow that the freezing system needs to remove from the ground in the cooling area at time t1, in W; This represents the integral over the entire cooling area volume, in meters (m). 3 ; The sensible heat change rate per unit volume of soil represents the rate at which a unit volume of soil absorbs or releases heat due to temperature change per unit time, with units of W / m³. 3 ; The rate of temperature change represents how quickly the temperature at a point changes over time. This represents the integral over the volume of the cooling area where a phase change is occurring, i.e., the region with a temperature near the freezing point, expressed in meters (m). 3 ; The latent heat release rate of phase change per unit volume represents the heat flow released per unit volume when water freezes into ice, with units of W / m³. 3 ; This represents the integral over the entire outer surface of the cooling area, in m². Heat flux density, representing the heat flow from the unfrozen area of ​​the external environment and groundwater into the frozen area through the boundary, calculated based on the geothermal gradient and Darcy's law, is expressed in W / m². Surface area, the interface area between the refrigerated area and the unfrozen external area, in m².

6. The adaptive cold supply method for freezing construction according to claim 5, characterized in that, In step 2, the formula for the relationship between flow rate and temperature difference is: ； in: The target temperature rise is represented by the temperature rise at a given predicted total heat load. To ensure heat balance in the monitoring area, the temperature that the brine should rise when it flows through the freezing pipe and is discharged is measured in °C. The predicted total heat load is the average heat load forecast value for a future period of time, calculated from the total heat load calculation formula, and is expressed in W. This represents the theoretical brine flow rate to be determined, in kg / s. is the specific heat capacity of brine, expressed in J / (kg·K).

7. The adaptive cold supply method for freezing construction according to claim 6, characterized in that, In step 3, the formula for calculating the effective frozen volume at time t1 is: ； in: The effective frozen soil volume at time t1, in meters. 3 ; This indicates that the volume integral is performed over the region in the entire three-dimensional space where the temperature is below a set threshold.

8. The adaptive cold supply method for freezing construction according to claim 7, characterized in that, In step 3, the statistical formula for cumulative energy consumption is: ； in: Cumulative energy consumption, in kWh; The instantaneous total power input to the relevant equipment, in kW; This represents the cumulative power consumption of all devices related to freezing from time t0 to time t1.

9. The adaptive cold supply method for freezing construction according to claim 7, characterized in that, The optimization calculation model in step 3 is as follows: ； in: The objective function value represents the electrical energy consumed to form one cubic meter of effective permafrost, expressed in kWh / m³. Cumulative energy consumption, in kWh; For effective frozen volume, the unit is m. 3 .

10. A method for adaptive supply of cooling capacity in freezing construction according to any one of claims 1-9, characterized in that, The freezing method construction area is divided into three or more cooling zones (1) along the circumference on the horizontal plane. Any two cooling zones (1) are adjacent. Each cooling zone (1) is equipped with an independent freezing pipe group (2) along the stratum depth direction. Each freezing pipe group (2) controls the brine flow rate separately through the terminal execution device. When any cooling zone (1) experiences a sudden change in heat load, the brine flow rate of the cooling zone (1) experiencing the sudden change in heat load and the brine flow rate of the two cooling zones (1) on both sides are controlled by the terminal execution device.

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