A method for using a three-tube winding type double-mode freezer capable of accurately measuring temperature and controlling a heat transfer process

Abstract

The present application relates to the model test and engineering application technology field of artificial stratum freezing, and discloses a use method of a three-pipe winding type double-mode freezing device capable of accurately measuring temperature and controlling heat transfer process, which is used for flowing back to the ground from a liquid return pipe after low-temperature refrigerant flows into a liquid supply pipe of the freezing device, and flowing back to a liquid return device of a ground circulation system, so that the circulation process of the low-temperature refrigerant in the freezing device is completed; the three-pipe winding type double-mode freezing device comprises a liquid supply pipe, a temperature measuring steel pipe and a liquid return pipe; the temperature measuring steel pipe is installed between the liquid supply pipe and the liquid return pipe, the liquid return pipe and the liquid supply pipe are wound with each other, and the bottom ends of the liquid return pipe and the liquid supply pipe are connected to form a liquid refrigerant circulator. The direct connection mode of the liquid supply pipe and the liquid return pipe is adopted, the phenomenon that a refrigerant circulation blind area appears at the bottom of the freezing device is avoided, the freezing device is formed when the liquid supply pipe and the liquid return pipe have a smaller diameter, and the influence of the thickness of the liquid supply pipe wall on the refrigerant circulation space is reduced.

Description

Technical Field

[0001] This invention relates to the field of model testing and engineering application technology of artificial ground freezing, specifically to a method of using a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process. Background Technology

[0002] Artificial ground freezing technology is a temporary reinforcement method that uses an artificial refrigeration system to circulate low-temperature refrigerant into the stratum through a freezer, causing the pore water in the stratum to freeze and form a continuous frozen soil curtain. This improves the strength and water-stopping performance of the stratum. Because the frozen soil curtain has a significant water-sealing effect, good bearing capacity, and also has the advantages of strong stratum adaptability, flexible support structure, high emergency efficiency, and safety and no pollution, it is often used in tunnel excavation, deep foundation pit support and underground emergency rescue projects in water-rich strata.

[0003] The freezer is a key piece of equipment for cold energy transfer during artificial freezing construction. It achieves the circulation of low-temperature refrigerant through ground-based liquid supply and return, completing the process of inputting cold energy into the stratum. Generally, a small-diameter liquid supply pipe is inserted into a large-diameter freezing pipe. The low-temperature refrigerant flows from the ground through the liquid supply pipe to the bottom of the freezing pipe, and then flows back to the ground through the annular space between the freezing pipe and the liquid supply pipe, thus forming a continuous circulation system of low-temperature refrigerant.

[0004] Because the supply pipe and the freezing pipe cannot be fixed together, the difference in the annular space at different locations results in a large difference in the freezing effect along the length of the freezer. Moreover, the circulation effect at the bottom of the freezing pipe is poor, which can easily cause a freezing blind zone at the bottom of the freezer. Especially in freezing model experiments, the diameter of the freezing pipe determined by geometric scaling is generally small. The wall thickness of the supply pipe will significantly affect the size of the annular space formed between the freezing pipe and the supply pipe. It is often impossible to form a freezer by inserting the supply pipe into the freezing pipe with a smaller diameter. At the same time, the supply pipe can only be placed back into the freezing pipe after the freezing pipe is constructed. Therefore, the freezing pipe must be straight to facilitate the installation of the supply pipe from the freezing pipe opening into the freezing pipe. The straight cylindrical steel pipe structure of the freezing pipe makes it impossible to accurately adjust and control the heat transfer process along the length of the freezer. In addition, considering the closed requirements of the low-temperature refrigerant circulation, the need for circulation in the freezing system results in a large pressure in the circulation space, making it impossible to install a temperature measuring system inside the freezing pipe to test the internal temperature of the freezer. Furthermore, it is difficult to wire the sensor out of the freezer.

[0005] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0006] In response to the problems in related technologies, this invention proposes a method for using a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process, thereby overcoming the aforementioned technical problems existing in the prior art.

[0007] Therefore, the specific technical solution adopted by the present invention is as follows:

[0008] A method for using a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process. This method is used to allow the low-temperature refrigerant to flow back to the ground from the return pipe after flowing into the supply pipe of the freezer, and then back to the return device of the ground circulation system, thus completing the circulation process of the low-temperature refrigerant in the freezer.

[0009] During the cycle, based on temperature data feedback from the temperature monitoring process, the freezer status and freezing effect are monitored in real time. The low-temperature refrigerant flow and temperature are dynamically adjusted to precisely control the heat transfer process and optimize the freezing effect. This includes: acquiring temperature and liquid refrigerant flow data based on the freezer's operation, establishing a synchronous temperature and flow monitoring framework, and outputting continuous time series data; identifying the temperature and flow coupling change trajectory types using the stable mapping method and continuous time series data, and analyzing the coupling change trajectory types based on the random forest model, outputting the contribution of temperature data and liquid refrigerant flow data to the freezer's operating status; constructing a multi-factor coupled temperature field fitting model based on the contribution, acquiring the dynamic process during freezer operation to assess changes in the formation's frozen layer thickness; analyzing the freezer's freezing effect based on changes in the frozen layer thickness, comparing the freezing effect with the freezing effect requirements, and outputting the freezer's freezing status to adjust the refrigerant flow and temperature during operation to optimize the freezer's freezing effect.

[0010] The three-tube wound dual-mode freezer includes: a supply pipe for supplying liquid refrigerant; a temperature measuring steel pipe for adjusting the temperature of the liquid refrigerant input into the supply pipe to control the heat transfer process; and a return pipe for ensuring the return of liquid refrigerant to ensure the freezer operates normally in low-temperature environments. The temperature measuring steel pipe is installed between the supply pipe and the return pipe, and the return pipe and the supply pipe are wound together, with the bottom ends of the return pipe and the supply pipe connected to form a liquid refrigerant circulator.

[0011] Preferably, the supply pipe and return pipe are wrapped around the outside of the temperature measuring steel pipe at a set interval and angle to form a tight-fitting structure, so as to reduce the installation diameter.

[0012] Preferably, the temperature measuring steel pipe and the liquid refrigerant in the liquid supply pipe are isolated to achieve the purpose of keeping the inside of the temperature measuring steel pipe in a pressureless state.

[0013] Preferably, the bottom ends of the supply pipe and the return pipe are connected to form a liquid refrigerant circulator, ensuring that the temperature measuring steel pipe is always in the middle position between the supply pipe and the return pipe, so that the cross-sectional shape and space of the liquid refrigerant circulator are consistent, and the state of the liquid refrigerant during the circulation process is avoided.

[0014] Preferably, the supply pipe and the return pipe can be wound in a manner where the supply pipe is on the outside and the return pipe is on the inside, or vice versa. The heat transfer effect at different positions can be adjusted according to the two winding methods to achieve precise control of the heat transfer process.

[0015] Preferably, the temperature measuring steel pipe can be in the shape of a curve with different curvatures to ensure that the temperature measuring steel pipe fits tightly against the middle of the liquid supply pipe and the liquid return pipe.

[0016] Preferably, the diameter, winding angle, and spacing of the supply pipe and return pipe can be adjusted according to the freezing capacity requirements;

[0017] When the required freezing capacity over a length range is lower than or equal to the target requirement, a winding method that reduces the number of turns between the supply and return pipes can be adopted.

[0018] When the required freezing capacity over a given length exceeds the target requirement, a winding method that increases the number of turns between the supply and return pipes can be used.

[0019] Preferably, the diameters of the supply pipe and the return pipe can be combined in different sizes;

[0020] When the diameter of the supply pipe is larger than the diameter of the return pipe, the circulation speed of the low-temperature refrigerant in the return pipe can be accelerated, thereby reducing the heat exchange time.

[0021] When the diameter of the supply pipe is smaller than the diameter of the return pipe, the circulation state of the low-temperature refrigerant at different pipe sections in the supply and return pipes can be changed.

[0022] Preferably, the temperature measuring steel pipe is hollow, and a temperature sensor is installed inside the temperature measuring steel pipe to ensure the measurement of the internal temperature of the liquid supply pipe and the liquid return pipe.

[0023] Preferably, when enhanced freezing is required, the temperature sensor inside the temperature measuring steel pipe can be removed, and a liquid supply pipe can be added inside the temperature measuring steel pipe. By introducing liquid nitrogen into the liquid supply pipe, the volume of the vaporized nitrogen expands to provide power, allowing the nitrogen to flow out through the annular space between the temperature measuring steel pipe and the liquid supply pipe, thus realizing the emergency process of liquid nitrogen freezing.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. This invention adopts a direct connection method between the supply pipe and the return pipe, which avoids the phenomenon of refrigerant circulation blind zone at the bottom of the freezer, ensuring the freezing effect at the bottom of the freezer. In addition, the direct connection method between the supply pipe and the return pipe can be used to form a freezer when the supply pipe and the return pipe have a smaller diameter, reducing the impact of the supply pipe wall thickness on the refrigerant circulation space. The winding method and spacing can adjust the heat transfer efficiency at different positions of the freezer and change the freezing effect at different positions along the length of the freezer.

[0026] 2. This invention uses a temperature-measuring steel pipe positioned in the middle of the freezer to accurately test the circulating temperature of the refrigerant inside the freezer, better protecting the temperature sensor and facilitating easy replacement when the sensor is damaged. It also provides a basis for adjusting the freezing effect of the freezer. Furthermore, the dual-mode freezing method allows for adjustment of the freezing effect at any time, addressing unconventional freezing needs such as temporary power outages and localized rapid freezing. It also makes it easier to precisely control the heat transfer process and achieve a refined freezing process. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a three-tube wound dual-mode freezer used in a method of using a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process according to an embodiment of the present invention.

[0029] Figure 2 This is an overall application flowchart of a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process according to an embodiment of the present invention.

[0030] Figure 3 This is a flowchart of the optimized freezing effect in the use of a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process according to an embodiment of the present invention.

[0031] Figure 4 This is a flowchart of the dynamic model construction process in the usage method of a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process according to an embodiment of the present invention.

[0032] Figure 5 This is a flowchart illustrating the identification of temperature and flow rate coupling change trajectory type in a method of using a three-tube wound dual-mode freezer that can accurately measure and control the heat transfer process, according to an embodiment of the present invention.

[0033] In the picture:

[0034] 1. Liquid supply pipe; 2. Temperature measuring steel pipe; 3. Liquid return pipe. Detailed Implementation

[0035] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0036] According to an embodiment of the present invention, a method for using a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process is provided.

[0037] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figure 1 The figure shows a method of using a three-tube wound dual-mode freezer that can accurately measure temperature and control the heat transfer process according to an embodiment of the present invention.

[0038] The three-tube wound dual-mode freezer includes:

[0039] Liquid supply pipe 1 is used to supply liquid refrigerant;

[0040] Temperature measuring steel pipe 2 is used to regulate the temperature of the liquid refrigerant input into the liquid supply pipe 1 in order to control the heat transfer process;

[0041] The return pipe 3 is used to ensure the return of liquid refrigerant, so as to ensure the normal operation of the freezer in a low-temperature environment;

[0042] Temperature measuring steel pipe 2 is installed between liquid supply pipe 1 and liquid return pipe 3. Liquid return pipe 3 and liquid supply pipe 1 are intertwined, and the bottom ends of liquid return pipe 3 and liquid supply pipe 1 are connected to form a liquid refrigerant circulator.

[0043] It should be explained that the liquid supply pipe 1 and the liquid return pipe 3 are tightly wrapped around the temperature measuring steel pipe 2 at a certain angle and spacing, and are connected at the bottom to form a liquid refrigerant circulation system. The temperature measuring steel pipe 2, which is always in the middle of the liquid supply pipe 1 and the liquid return pipe 3, can accurately test the internal temperature of the freezer. Based on the test temperature, the temperature and flow rate of the low-temperature liquid refrigerant input into the liquid supply pipe 1 are adjusted to achieve precise control of the heat transfer process of the freezer. Furthermore, after arranging a soft liquid supply pipe inside the temperature measuring steel pipe 2, a liquid nitrogen freezing circulation system can be formed, realizing a dual-mode freezing method of rapid low-temperature freezing of liquid nitrogen and synchronous circulation of liquid refrigerant.

[0044] Furthermore, the liquid supply pipe 1 and the liquid return pipe 3 are tightly wrapped with the temperature measuring steel pipe 2, and the temperature measuring steel pipe 2 is always positioned between the liquid supply pipe 1 and the liquid return pipe 3, thereby achieving the function of accurately testing the internal temperature of the freezer. The direct contact between them enhances the cold energy transfer effect between the pipes, making the overall temperature distribution of the freezer more uniform, reducing the overall cross-sectional diameter of the freezer, and controlling the space required for the freezer to be placed.

[0045] Meanwhile, a temperature sensor is installed inside the temperature-measuring steel pipe 2. This ensures accurate measurement of the temperature inside the freezer, and the sensor's placement does not affect the refrigerant circulation in the liquid refrigerant cycle, enabling precise control of the freezer's heat transfer process. The temperature-measuring steel pipe 2 is isolated from the liquid refrigerant, achieving a pressure-free state within it. This facilitates the connection of the temperature sensor leads inside the pipe without requiring a sealing device at the pipe opening. Furthermore, the temperature sensor inside the pipe can be repositioned as needed to meet temperature measurement requirements at different locations along the entire length of the freezer. The sensor can also be removed at any time for replacement of damaged or new sensors to meet various temperature measurement needs. Additionally, the temperature-measuring steel pipe 2 can be curved along its length, allowing for the formation of any curved freezer shape to meet construction requirements through the tight wrapping of the supply pipe 1 and return pipe 3.

[0046] During application, different diameter supply pipes 1 and return pipes 3 can be selected according to construction needs to adjust the circulation speed of the low-temperature refrigerant in supply pipes 1 and return pipes 3, thereby changing the heat transfer efficiency and freezing effect of the freezer. At the same time, the winding angle and spacing of supply pipes 1 and return pipes 3 can be adjusted along the length of the freezer to control the heat dissipation efficiency at different positions of the freezer and precisely control the heat transfer process of the freezer.

[0047] Furthermore, the liquid supply pipe 1 and liquid return pipe 3, which are wrapped around the temperature measuring steel pipe 2, can be wound alternately and at intervals. Alternatively, the liquid return pipe 3 can be wound inside and the liquid supply pipe 1 outside, or the liquid return pipe 3 can be wound outside and the liquid supply pipe 1 inside, so as to adjust the heat transfer effect at different positions of the freezer and achieve precise control of the heat transfer process of the freezer. In case of power outage emergency handling, the internal freezer can be frozen with liquid nitrogen while the external freezer is circulated with conventional liquid refrigerant. In case of conventional enhanced freezing, the external liquid nitrogen can be frozen while the internal liquid refrigerant is circulated with conventional liquid refrigerant, so as to adapt to different freezing construction conditions.

[0048] The diameter, winding angle, and spacing of the supply pipe 1 and return pipe 3 can be adjusted according to the freezing cold capacity requirements, thereby changing the freezing effect along the length of the freezer. When the required freezing efficiency is low along the length of the freezer, a sparser winding method can be used. Conversely, within the range where the freezing efficiency needs to be improved, the number of winding turns of the supply pipe 1 and return pipe 3 can be increased to enhance the freezing effect. When the required freezing effect varies, a winding method with the supply pipe 1 inside and the return pipe 3 outside, or vice versa, can be used to change the heat transfer effect at different locations and precisely control the freezing process. Furthermore, a combination of sparse supply pipe 1 winding with dense return pipe 3 winding, or vice versa, can be used to create different heat transfer efficiencies along the length of the freezer.

[0049] It should be noted that the sizes of the supply pipe 1 and return pipe 3 in the freezer can be different. By changing the cross-sections, the circulation state of the low-temperature refrigerant in the supply pipe 1 and return pipe 3 can be achieved, thereby changing the cold transfer efficiency. By using a combination of a large diameter supply pipe 1 and a small diameter return pipe 3, the low-temperature refrigerant in the return pipe 3 circulates faster and has a shorter heat exchange time with the surrounding stratum, thus adjusting the heat transfer efficiency of the freezer. Alternatively, the diameter of the return pipe 3 can be larger than the diameter of the supply pipe 1, thereby changing the circulation state of the low-temperature refrigerant in different pipe sections. The winding freezer structure arranges the supply pipe 1 and return pipe 3 in an alternating and tightly fitted manner. The differences in the circulation states affect each other, reducing the impact of differences in heat transfer efficiency during the freezing process. Correspondingly, the joints of the supply pipe 1 and return pipe 3 can be interchanged to adjust the freezing effect at different positions along the length of the freezer.

[0050] The temperature-sensing steel pipe 2, located between the supply pipe 1 and the return pipe 3, can be used to test the temperature between them without affecting the circulation of the low-temperature refrigerant. The temperature sensor, positioned inside the steel pipe 2, is far from the surrounding soil, allowing for both temperature testing and sensor protection to prevent damage during testing. Furthermore, the steel pipe 2 is separate from the liquid refrigerant circulation system, with no pressure inside. Sealing the steel pipe 2 is unnecessary during freezing; the lead wires of the temperature-sensing system can be directly connected to it, facilitating connection to the testing system. The temperature and flow rate of the refrigerant in the supply pipe 1 can be adjusted based on the temperature data to regulate the freezing effect. If necessary, the supply pipe 1 and return pipe 3 can be interchanged to adjust the circulation direction of the low-temperature refrigerant, thus precisely controlling the freezing effect. When the temperature sensor inside the steel pipe 2 is damaged or needs replacement, it can be easily removed, and the temperature-sensing system rearranged to achieve accurate temperature measurement.

[0051] Meanwhile, according to construction requirements, the temperature measuring steel pipe 2 can be designed into curves with different curvatures, or even complex curves such as S-shapes. The supply pipe 1 and return pipe 3, which are tightly wrapped around the temperature measuring steel pipe 2, form a curved freezing device. During construction, the curved freezing device can be buried by directional drilling, while in the model test, the freezing device can be directly placed in the stratum to form an irregular freezing wall, thereby precisely adjusting the construction effect of the freezing device.

[0052] To facilitate understanding of the above technical solutions of the present invention, the working principle or operation method of the present invention in actual process will be described in detail below.

[0053] like Figures 2 to 5As shown, in practical applications, the temperature measuring steel pipe 2 is processed according to the curve required by the freezing design. The diameter of the temperature measuring steel pipe 2 is based on meeting the arrangement requirements of the temperature sensor. At the same time, the liquid supply pipe 1 and the liquid return pipe 3 of different diameters are wrapped around the temperature measuring steel pipe 2 in different ways such as different angles, spacing, and internal and external winding according to the freezing effect requirements. After being connected at the bottom, they form a loop to obtain the freezer.

[0054] After drilling holes in the stratum using a directional drill bit, or directly placing the freezer in the stratum or soil during model tests, the low-temperature refrigerant in the freezing system is connected to the supply pipe 1 of the freezer on the ground, and the return pipe 2 is connected to the return system of the freezing system. At the same time, a temperature sensor is placed in the temperature measuring steel pipe 2, and the connected temperature field testing system is connected to a computer to realize automatic temperature data acquisition.

[0055] The low-temperature refrigerant flows from the liquid supply device of the circulation system into the liquid supply pipe 1 of the freezer. After passing through the bottom connection position, it flows back to the ground through the return pipe 3 and then back to the return device of the ground circulation system, completing the circulation process of the low-temperature refrigerant in the freezer. Based on the temperature data feedback during the temperature monitoring process, the status of the freezer and the freezing effect are monitored in real time, and the flow rate and temperature of the low-temperature refrigerant are dynamically adjusted to precisely control the heat transfer process and optimize the freezing effect.

[0056] When the temperature sensor is damaged or needs to be replaced, the temperature sensor inside the temperature measuring steel pipe 2 can be directly removed and replaced without affecting the normal freezing construction. At the same time, in case of power failure, the freezing system cannot circulate normally or in case of emergency, such as needing to strengthen freezing, the temperature sensor inside the temperature measuring steel pipe 2 can be removed and lowered into the liquid supply pipe 1 to form a liquid nitrogen freezing system. By introducing liquid nitrogen into the liquid supply pipe 1, the volume expansion of the vaporized nitrogen provides power, causing the nitrogen to flow out through the annular space between the temperature measuring steel pipe 2 and the liquid supply pipe 1, realizing the liquid nitrogen freezing emergency process.

[0057] During the freezing process, when localized areas require cryogenic freezing with liquid nitrogen, both the external liquid refrigerant circulation system and the internal liquid nitrogen circulation system can be simultaneously switched to cryogenic freezing mode on the ground. After rapid freezing for a period of time, the internal liquid nitrogen circulation system is switched back to a conventional liquid refrigerant circulation system for wall insulation, thus implementing freezing modes required for different freezing conditions. All interfaces of the freezer are located on the ground, allowing for adjustments to the type and temperature of the refrigerant in the circulation system during freezing. This enables different modes, such as circulating liquid refrigerant in both systems, circulating liquid nitrogen vaporization in both systems, or circulating liquid nitrogen refrigerant and liquid nitrogen vaporization separately inside and outside the system. Different freezing times can be achieved by controlling parameters such as flow rate and temperature, allowing for adjustment of heat transfer efficiency along the length and over time, thus achieving precise control of the freezing effect during construction. After freezing, the freezer is disconnected from the ground circulation system. After removal, the freezer can be recycled and maintained for use in subsequent projects or tests.

[0058] It should be explained that the specific steps involved in monitoring the freezer status and freezing effect in real time based on temperature data feedback from the temperature monitoring process, dynamically adjusting the low-temperature refrigerant flow and temperature, precisely controlling the heat transfer process, and optimizing the freezing effect are as follows:

[0059] Acquire temperature data and liquid refrigerant flow data during the freezing process, and use temperature field fitting technology to construct a dynamic model of the freezer operation based on the temperature data and liquid refrigerant flow data.

[0060] The freezing effect of the freezer is analyzed based on the dynamic model to assess the change in the thickness of the frozen layer, and the freezing effect is compared with the freezing effect requirements to output the freezing status of the freezer.

[0061] Once the target freezing state is achieved, operate according to historical liquid refrigerant flow and temperature;

[0062] When the freezing state does not meet the target expectation, a graph structure relationship is constructed based on temperature data, liquid refrigerant flow data and changes in the thickness of the frozen layer, and the nonlinear coupling behavior of the freezing energy efficiency of the freezer is captured.

[0063] A virtual freezer is introduced based on the nonlinear coupling behavior of cold energy efficiency. The required liquid refrigerant flow rate and temperature are analyzed to achieve the target frozen layer thickness change, and the refrigerant flow rate and temperature are adjusted during operation.

[0064] The heat transfer process of the freezer during operation is controlled based on the adjusted refrigerant flow and temperature, and the freezing effect of the freezer is optimized based on the control process.

[0065] The process of acquiring temperature and liquid refrigerant flow data during freezing, and then constructing a dynamic model of the freezer's operation based on this data using temperature field fitting technology, includes: acquiring temperature and liquid refrigerant flow data based on the freezer's operation, establishing a synchronous monitoring framework for temperature and flow using this data, and outputting continuous time series data; identifying the types of coupled temperature and flow change trajectories using the stable mapping method and continuous time series data, analyzing these types of trajectories based on a random forest model, and outputting the contribution of temperature and liquid refrigerant flow data to the freezer's operating state; and constructing a multi-factor coupled temperature field fitting model based on the contribution of the freezer's operating state to dynamically depict the freezer's operation and obtain the dynamic process during freezer operation.

[0066] Specifically, outlier removal and missing value completion are required for the raw temperature and refrigerant flow data. The rate of temperature change and the rate of refrigerant flow change in adjacent time periods are calculated to capture their dynamic characteristics. Based on the stable mapping method, the rate of temperature change and the rate of refrigerant flow change are used to introduce three indicators: similarity, number of changes, and diversity, to identify the type of temperature and flow coupled change trajectory.

[0067] Based on temperature field fitting technology, and according to the temperature-flow coupling change trajectory type, temperature data and refrigerant flow data are used as core independent variables, and auxiliary factors such as soil thermal conductivity and ambient temperature are incorporated to construct a multivariate coupled dynamic model of freezer operation. The contribution of each driving factor is analyzed using a random forest model, and the model accuracy is verified by combining engineering measured data. The characteristics of driving factors in different trajectory type partitions are compared, and the parameters of the dynamic model of freezer operation are optimized to achieve dynamic characterization of the freezer operation process and obtain the dynamic process of freezer operation.

[0068] It should be explained that by simulating and analyzing the liquid refrigerant flow rate and temperature required to achieve the target frozen layer thickness through a virtual freezer, and adjusting the refrigerant flow rate and temperature during operation, algorithms such as virtual simulation, cold energy efficiency modeling, and deep reinforcement learning (DRL) can be combined to ensure dynamic response to various changes during the freezing process and precise control of the freezing effect.

[0069] By introducing a virtual freezer, a three-dimensional physical model is constructed based on the current freezer's geometry, refrigerant fluid characteristics, and initial temperature field. The virtual freezer can use numerical simulation techniques based on the finite element method (FEM) or the lattice Boltzmann method (LBM) to dynamically calculate the heat transfer and changes during the freezing process. A temperature and refrigerant flow prediction model is established using a deep neural network (DNN). The model's inputs include the initial temperature inside and outside the freezer, the refrigerant flow rate, and the initial thickness of the frozen layer. Based on the prediction model, the refrigerant flow rate and temperature are dynamically adjusted. The state of the frozen layer consists of parameters such as the current frozen layer thickness, refrigerant flow rate, and refrigerant temperature. The goal is to maximize the speed at which the frozen layer thickness reaches the predetermined target, while ensuring optimal cooling efficiency in the process.

[0070] Specifically, the virtual freezer can be constructed using a fast differentiable lattice model (differentiable implementation of finite difference / lattice Boltzmann) or a finite element / CFD numerical solver as precise labels. Automatic differentiation is performed on the virtual freezer, enabling direct calculation of heat transfer sensitivity for refrigerant flow and temperature control variables. A graph neural network (GNN) is used to represent the spatial grid of the freezer and the topological coupling of the refrigerant channels as a graph. Node features include local temperature, phase probability, and material properties, while edges represent thermal / fluid coupling. The GNN is trained as a multi-fidelity surrogate model, predicting the future evolution of the frozen layer thickness and providing uncertainty estimates through the differentiable approximation of the evaporation / condensation latent heat terms. Based on the future evolution of the frozen layer thickness and the uncertainty estimates, a continuously differentiable loss function is constructed using differentiability and automatic differentiation tools: L = α·|h(t) f )-h target |+β·Energy Consumption+γ·Freezing Uniformity Penalty, where α is the weighting coefficient of the target frozen layer thickness error, β is the weighting coefficient of energy consumption, γ is the weighting coefficient of freezing uniformity penalty, h(t) f ) is the frozen layer at the final time point t f The actual thickness, h is the thickness of the frozen layer, h target It is the thickness of the target frozen layer.

[0071] The optimal continuous trajectory for refrigerant flow and temperature is obtained by solving the loss function. The Pareto front for freezing efficiency (freezing rate, energy consumption, uniformity) is constructed. A multi-objective evolutionary algorithm (NSGA-II variant) is used to select the trade-off point. This selection is then transformed into a dynamic adjustment analysis of the MPC objective weights to achieve the required liquid refrigerant flow and temperature when the target frozen layer thickness changes. The refrigerant flow and temperature during operation are then adjusted.

[0072] In summary, this invention addresses the challenges of constructing the annular space within traditional manual freezers, including difficulties in controlling the spatial shape and testing the internal circulating refrigerant. Particularly when the freezing pipe diameter is small, the thickness of the supply pipe wall occupies a significant portion of the annular space between the thinner freezing pipe and the supply pipe, reducing the internal circulating space. The invention proposes a freezer formed by directly winding the supply pipe 1 and return pipe 3 around the temperature-measuring steel pipe 2. This results in a freezer with a smaller outer diameter, meeting the requirements for small-diameter freezers. The supply pipe 1 and return pipe 3 are connected at the bottom to form a circulation system, facilitating the introduction and return of cryogenic liquid refrigerant from the ground. The intermediate temperature-measuring steel pipe 2 allows for the placement of temperature measurement points for testing the internal temperature of the freezer, and also allows for the placement of the supply pipe 1 within it to form a liquid nitrogen freezing system. This satisfies the need for simultaneous construction under both conventional brine freezing and liquid nitrogen cryogenic freezing modes.

[0073] This application utilizes a temperature-measuring steel pipe 2 positioned between the supply pipe 1 and the return pipe 3 to precisely obtain the internal temperature of the freezer during the freezing process. This temperature serves as the basis for adjusting the low-temperature refrigerant circulation flow and temperature at the ground inlet. By precisely controlling the freezing construction parameters, a refined freezing construction effect is achieved. Furthermore, since it is not necessary to insert the supply pipe 1 into the freezing pipe, the direction of the curve is controlled by the intermediate temperature-measuring steel pipe 2. The freezer can be processed into any shape according to construction needs. In different areas along the length of the freezer, the different angles and spacings of the winding of the supply pipe 1 and the return pipe 3 can be adjusted to control different freezing effects along the length of the freezer, thereby further precisely controlling the heat transfer process of the freezer.

[0074] This invention achieves accurate temperature measurement within the freezer through a tightly wound structure, overcomes the influence of the liquid supply pipe wall thickness on the annular circulation space when the freezing pipe diameter is small, and realizes the combined effect of two freezing modes. It can improve the control accuracy of the heat transfer process and the freezing effect during the freezing process, and is suitable for model tests of artificial freezing or refined freezing construction projects.

[0075] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for using a three-tube wound dual-mode freezer capable of precise temperature measurement and heat transfer process control, characterized in that, This method of use is used to allow the low-temperature refrigerant to flow back to the ground from the return pipe (3) after flowing into the supply pipe (1) of the freezer, and then back to the return device of the ground circulation system, thus completing the circulation process of the low-temperature refrigerant in the freezer. During the cycle, based on temperature data feedback from the temperature monitoring process, the freezer status and freezing effect are monitored in real time. The low-temperature refrigerant flow and temperature are dynamically adjusted to precisely control the heat transfer process and optimize the freezing effect. This includes: acquiring temperature and liquid refrigerant flow data based on the freezer's operation, establishing a synchronous temperature and flow monitoring framework, and outputting continuous time series data; identifying the temperature and flow coupling change trajectory types using the stable mapping method and continuous time series data, and analyzing the coupling change trajectory types based on the random forest model, outputting the contribution of temperature data and liquid refrigerant flow data to the freezer's operating status; constructing a multi-factor coupled temperature field fitting model based on the contribution, acquiring the dynamic process during freezer operation to assess changes in the formation's frozen layer thickness; analyzing the freezer's freezing effect based on changes in the frozen layer thickness, comparing the freezing effect with the freezing effect requirements, and outputting the freezer's freezing status to adjust the refrigerant flow and temperature during operation to optimize the freezer's freezing effect. The three-tube winding dual-mode freezer includes: a liquid supply pipe (1) for supplying liquid refrigerant; a temperature measuring steel pipe (2) for adjusting the temperature of the liquid refrigerant input into the liquid supply pipe (1) to achieve the purpose of controlling the heat transfer process; and a return pipe (3) for ensuring the return state of the liquid refrigerant to ensure the normal operation of the freezer in a low-temperature environment. The temperature measuring steel pipe (2) is installed between the liquid supply pipe (1) and the return pipe (3), and the return pipe (3) is wound around the liquid supply pipe (1), and the bottom end of the return pipe (3) is connected to the liquid supply pipe (1) to form a liquid refrigerant circulator.

2. The method of using the three-tube wound dual-mode freezer with precise temperature measurement and heat transfer process control according to claim 1, characterized in that, The supply pipe (1) and the return pipe (3) are wrapped around the outside of the temperature measuring steel pipe (2) at a set distance and angle to form a close-fitting structure, so as to reduce the installation diameter.

3. The method of using a three-tube wound dual-mode freezer capable of precise temperature measurement and heat transfer process control according to claim 1, characterized in that, The temperature measuring steel pipe (2) is isolated from the liquid refrigerant in the liquid supply pipe (1), so that the inside of the temperature measuring steel pipe (2) is in a pressureless state.

4. The method of using the three-tube wound dual-mode freezer with precise temperature measurement and heat transfer process control according to claim 1, characterized in that, The liquid supply pipe (1) is connected to the bottom end of the liquid return pipe (3) to form a liquid refrigerant circulator, ensuring that the temperature measuring steel pipe (2) is always in the middle position between the liquid supply pipe (1) and the liquid return pipe (3), so that the cross-sectional shape of the liquid refrigerant circulator is consistent with the space, and the state of the liquid refrigerant during the circulation process is avoided.

5. The method of using a three-tube wound dual-mode freezer capable of precise temperature measurement and heat transfer process control according to claim 1, characterized in that, The supply pipe (1) and the return pipe (3) can be wound in a manner where the supply pipe (1) is on the outside and the return pipe (3) is on the inside, or the return pipe (3) is on the outside and the supply pipe (1) is on the inside. The heat transfer effect at different positions can be adjusted according to the two winding methods to achieve precise control of the heat transfer process.

6. The method of using a three-tube wound dual-mode freezer capable of precise temperature measurement and heat transfer process control according to claim 1, characterized in that, The shape of the temperature measuring steel pipe (2) can be a curve with different curvatures to ensure that the temperature measuring steel pipe (2) fits tightly against the middle of the liquid supply pipe (1) and the liquid return pipe (3).

7. The method of using a three-tube wound dual-mode freezer capable of precise temperature measurement and heat transfer process control according to claim 1, characterized in that, The diameter, winding angle and spacing of the liquid supply pipe (1) and the liquid return pipe (3) can be adjusted according to the freezing cold capacity requirements; When the required freezing cold capacity over a length range is lower than or equal to the target requirement, a winding method that reduces the number of turns between the supply pipe (1) and the return pipe (3) can be adopted. When the required freezing capacity over a length range is higher than the target requirement, a winding method can be adopted that increases the number of turns between the supply pipe (1) and the return pipe (3).

8. The method of using a three-tube wound dual-mode freezer capable of precise temperature measurement and heat transfer process control according to claim 1, characterized in that, The diameter of the supply pipe (1) and the diameter of the return pipe (3) can be combined in different sizes; When the diameter of the supply pipe (1) is greater than the diameter of the return pipe (3), the circulation speed of the low-temperature refrigerant in the return pipe (3) can be accelerated to reduce the heat exchange time. When the diameter of the supply pipe (1) is smaller than the diameter of the return pipe (3), the circulation state of the low-temperature refrigerant at different pipe sections in the supply pipe (1) and the return pipe (3) can be changed.

9. The method of using a three-tube wound dual-mode freezer capable of precise temperature measurement and heat transfer process control according to claim 1, characterized in that, The temperature measuring steel pipe (2) is hollow, and a temperature sensor is installed inside the temperature measuring steel pipe (2) to ensure the temperature of the inside of the liquid supply pipe (1) and the liquid return pipe (3).

10. The method of using a three-tube wound dual-mode freezer capable of precise temperature measurement and heat transfer process control according to claim 1, characterized in that, When it is necessary to strengthen the freezing process, the temperature sensor inside the temperature measuring steel pipe (2) can be removed, and the liquid supply pipe (1) can be added inside the temperature measuring steel pipe (2). Liquid nitrogen is introduced into the liquid supply pipe (1), so that the volume of the vaporized nitrogen expands to provide power, and the nitrogen flows out through the annular space between the temperature measuring steel pipe (2) and the liquid supply pipe (1), thus realizing the liquid nitrogen freezing emergency process.

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