A Non-Contact Method and System for Detecting the Position of Ice Slurry Formation Front Based on the Curvature of the Temperature Field on the Cooling Medium Side

Abstract

This invention belongs to the field of ice slurry preparation technology, and particularly relates to a non-contact method and system for detecting the position of the ice slurry formation front based on the curvature of the temperature field on the cooling medium side. The method includes: acquiring temperature measurements collected by multiple temperature sensors installed on the cooling medium side of a heat exchanger; constructing a smoothed temperature function along the cooling medium side of the heat exchanger based on the multiple temperature measurements; calculating the signed temperature curvature corresponding to each position within the temperature detection interval according to the smoothed temperature function; determining the extreme position of the signed temperature curvature in a preset curvature direction, and using this extreme position as an estimate of the position of the ice slurry formation front. The detection method of this invention solves many shortcomings of existing technologies, such as high pollution risk, limited observation conditions, poor detection accuracy, and low level of intelligence, and combines cleanliness, stability, accuracy, and scalability.

Description

Technical Field

[0001] This invention belongs to the field of ice slurry preparation technology, and particularly relates to a non-contact method and system for detecting the position of the ice slurry generation front based on the curvature of the temperature field on the cooling medium side. Background Technology

[0002] Ice slurry is a solid-liquid two-phase flowable fluid formed by mixing tiny ice crystal particles with liquid water or a low-freezing-point refrigerant. It possesses outstanding technical advantages such as high cold storage density, high heat transfer coefficient, isothermal phase-change refrigeration, and excellent fluidity, making it a new generation of high-efficiency low-temperature cold storage and heat exchange medium. Currently, ice slurry is widely used in many fields such as food cold chain preservation, medical precision cooling, low-temperature transportation of biological products, commercial building air conditioning cold storage, and industrial low-temperature process control. It is suitable for various scenarios requiring refined, high-efficiency, and low-loss low-temperature refrigeration, possessing extremely high engineering application value and market promotion prospects.

[0003] In industrial ice slurry preparation systems, the spatial location, development speed, and operational stability of the ice crystal formation region are key parameters determining the quality of the finished ice slurry and the safety of system operation. Specifically, the dynamic changes in the ice crystal formation front directly affect the steady-state ice content of the ice slurry, overall heat exchange efficiency, and pipeline flow resistance, and are also a major cause of pipeline ice blockage and equipment malfunctions. If the dynamic state of the ice crystal formation front cannot be accurately and in real-time monitored, problems such as excessive fluctuations in ice content, decreased heat exchange performance, and abnormal increases in pipeline resistance can easily occur. In severe cases, this can lead to localized ice crystal accumulation, pipeline ice blockage, and shutdowns, significantly reducing the operational stability and continuous production capacity of the ice slurry preparation system, and hindering the full realization of the advantages of ice slurry's low-temperature heat exchange and cold storage. Therefore, achieving accurate online detection of the ice crystal formation front position during ice slurry preparation is a crucial prerequisite for ensuring ice slurry quality, optimizing system operating parameters, mitigating ice blockage risks, and improving equipment operating efficiency.

[0004] Currently, the mainstream detection methods for the freezing state of ice slurry in the industrial field mainly include four categories: direct contact temperature detection, manual sampling detection, equipment visualization observation, and indirect inference based on pressure difference and flow parameters. Among them, direct contact temperature detection requires placing the sensor probe directly into the ice slurry fluid. Although it can directly collect temperature data, the probe is in direct contact with the ice slurry and materials, which can easily cause media contamination. This cannot meet the high-standard clean application requirements of food cold chain, medical and health, and biological products, thus limiting its applicability. At the same time, the probe is in long-term contact with low-temperature two-phase fluid, which is prone to frost and ice formation, causing drift in detection accuracy and increased equipment failure rate. Manual sampling detection is an offline intermittent detection method with strong detection lag. It cannot achieve real-time dynamic monitoring of the ice crystal formation front, making it difficult to adapt to continuous and automated industrial preparation scenarios. In addition, manual operation has large errors and low efficiency. Visual observation methods rely on observation windows provided by the equipment to monitor its internal state. However, existing ice slurry preparation equipment is covered with thick thermal insulation layers to reduce cooling loss and ensure refrigeration efficiency. This severely limits the range and viewing angle of the observation windows, making it impossible to comprehensively and accurately determine the actual location and development status of ice crystal formation areas inside the equipment. Consequently, the accuracy and completeness of the observations are extremely poor. Indirect inference methods based on pressure difference and flow rate changes can only indirectly predict the overall ice formation state of the ice slurry through macroscopic operating parameters of the system. They cannot accurately locate the local ice crystal formation front, resulting in low detection accuracy and poor specificity. They cannot provide reliable data support for precise control of ice slurry preparation parameters and early warning of ice blockage risks.

[0005] In summary, existing ice slurry formation state detection technologies suffer from several drawbacks, including susceptibility to media contamination, detection lag, poor visibility, low detection accuracy, and inability to accurately locate the ice crystal formation front online. These limitations make it difficult to simultaneously meet the demands of clean production, real-time online detection, and high-precision state monitoring, severely hindering the automated, precise, and stable operation of ice slurry preparation systems. To address these shortcomings, there is an urgent need to develop a non-contact, media-free detection method capable of accurately estimating the ice slurry formation front in real time. This would overcome the technical bottlenecks of existing technologies and ensure the quality of ice slurry preparation and the safety of equipment operation. Summary of the Invention

[0006] This invention aims to solve the problems in existing ice slurry formation state detection, such as the sensor being prone to contact with ice slurry, the difficulty in observing the internal phase change process under heat preservation conditions, and the difficulty in determining the position of the ice formation front online. It provides a non-contact, media-free detection method and system that can accurately estimate the position of the ice slurry formation front in real time.

[0007] In view of this, the present invention provides a non-contact method for detecting the position of the ice slurry formation front based on the curvature of the temperature field on the cooling medium side, comprising: Acquire temperature measurements from multiple temperature sensors located on the cooling medium side of the heat exchanger; Based on multiple temperature measurements, a friction-smooth temperature function is constructed on the cooling medium side of the heat exchanger. The signed temperature curvature at each position within the temperature detection interval is calculated based on the aforementioned smoothed temperature function along the path. The extreme position of the signed temperature curvature in the preset curvature direction is determined, and this extreme position is used as an estimate of the position of the ice magma formation front.

[0008] Furthermore, after acquiring temperature measurements from multiple temperature sensors, the original temperature measurements are preprocessed with time filtering, and then a smoothed temperature function along the cooling medium side of the heat exchanger is constructed based on the filtered stable temperature data.

[0009] Furthermore, after calculating the signed temperature curvature at each location using the along-the-path smoothing temperature function, an axial coordinate determination system is established based on the flow direction of the cooling medium in the heat exchanger. Based on the preset curvature direction, the extreme value of curvature is retrieved within the effective detection range covered by the temperature sensor to determine the extreme value position of the signed temperature curvature in the preset curvature direction.

[0010] Furthermore, the multiple temperature sensors are arranged at equal or non-equal intervals along the flow direction of the cooling medium in the heat exchanger.

[0011] Furthermore, the multiple temperature sensors are arranged at non-equidistant intervals along the flow direction of the cooling medium in the heat exchanger. The spacing between the temperature sensors in the preset key detection area is smaller than that in other areas. The preset key detection area at least includes the operating range within the heat exchanger near the ice slurry formation front.

[0012] Furthermore, the smoothed temperature function along the path is obtained through spatial smoothing fitting or online state estimation based on a physical model.

[0013] Furthermore, the signed temperature curvature satisfies the following calculation formula: ; in, Axial position The signed temperature curvature at that location, The positive or negative sign indicates the direction of curvature of the temperature curve along the cooling medium side; To construct the obtained friction-smooth temperature function, and These are the first and second derivatives of the smoothed temperature function along the path, respectively.

[0014] Furthermore, the detection method also includes: After obtaining an estimate of the position of the ice slurry formation front, at least one of the following is adjusted based on the estimate: cooling medium flow rate, ice slurry channel flow rate, cooling medium inlet temperature, or cooling power.

[0015] Furthermore, the location of the minimum value of the signed temperature curvature in the negative direction is determined, and this minimum value location is used as an estimate of the location of the ice magma formation front.

[0016] This invention also provides a non-contact ice slurry formation front position detection system based on the curvature of the temperature field on the cooling medium side. The detection system uses the aforementioned detection method to detect the ice slurry formation front position. The detection system includes: A temperature sensor array is set at multiple spatial locations on the cooling medium side of the heat exchanger for ice slurry preparation to collect the temperature at the corresponding locations; A temperature acquisition module is used to acquire the temperature measurement values ​​output by the temperature sensor array; The processing module is used to calculate an estimated value of the position of the ice magma formation front based on the temperature measurement value; The output and display module is used to output and display the estimated value of the position of the ice lava formation front or the ice lava formation status information.

[0017] The non-contact ice slurry formation front position detection method and system based on the temperature field curvature of the cooling medium side provided in this application addresses the industry pain points of existing ice slurry ice formation state detection technologies, such as medium contamination, limited observation, detection lag, low positioning accuracy, and difficulty in intelligent linkage control. Relying on a non-contact temperature measurement architecture, temperature curvature feature recognition mechanism, and online data analysis strategy, it possesses outstanding technological advancement, engineering practicality, and scenario adaptability. Specific technical advantages are as follows: First, by adopting an external temperature measurement architecture on the cooling medium side, the risk of medium contamination is completely avoided, making it suitable for high-standard cleanroom applications. This invention arranges the temperature sensor array entirely on the heat exchange wall surface of the cooling medium flow channel of the heat exchanger, ensuring no direct contact with the ice slurry solid-liquid two-phase fluid throughout the process. This is completely different from traditional insertion-type contact temperature measurement schemes. Through non-contact temperature measurement on the wall surface, the problem of medium contamination in the detection process is eliminated from the physical structure, significantly expanding the application scenarios of ice slurry preparation systems, especially suitable for industrial production environments with high cleanliness requirements.

[0018] Secondly, it eliminates the reliance on visual observation and is adaptable to fully insulated equipment structures and industrial closed-loop operation conditions. This invention does not depend on visual observation structures; it indirectly and accurately inverts the phase change formation state of ice slurry inside the equipment by analyzing temperature curvature characteristics solely through temperature data along the cooling medium side. It is not limited by the equipment's insulation structure or closed-loop operation, perfectly adapting to the operational needs of industrial fully insulated closed-loop heat exchange equipment, and solving the long-standing technical problem of the inability to monitor the ice formation state of ice slurry under insulation conditions online.

[0019] Third, relying on the unique temperature curvature characteristics of phase change, this invention achieves high-precision, lag-free online positioning of the ice slurry formation front. The ice slurry phase change process generates significant latent heat absorption and release effects, causing abrupt changes in the local heat transfer characteristics of the phase change front. The corresponding axial temperature field exhibits unique bending characteristics distinct from the pure liquid supercooled region and stable ice-forming region. This invention innovatively utilizes signed temperature curvature to quantify the temperature field bending morphology. By identifying the extreme values ​​of the curvature characteristics corresponding to the phase change front, it accurately pinpoints the location of the ice slurry formation front and the phase change interval. Compared to traditional manual sampling offline detection and indirect inference based on pressure difference and flow rate, this invention enables continuous, uninterrupted online real-time detection without detection lag. It can also identify subtle changes in operating conditions such as weak local phase change anomalies and minor frontal shifts, exhibiting strong resistance to fluid turbulence disturbances and temperature measurement noise interference, significantly improving detection accuracy and stability.

[0020] Fourth, it boasts strong scalability, enabling deep integration with intelligent control, fault early warning, and digital twin systems to support the intelligent upgrade of ice slurry preparation. The quantitative data on the ice slurry generation front position output by this invention provides core characteristic parameters for the intelligent control of the ice slurry system, allowing for multi-dimensional engineering application expansion. On one hand, it can combine the front position offset status to achieve closed-loop linkage adjustment of core operating parameters such as cooling medium flow rate, ice slurry channel flow rate, cooling medium inlet temperature, and system cooling power, realizing stable control of ice slurry ice content and optimal regulation of heat exchange efficiency. On the other hand, by monitoring abnormal front offset and large fluctuations, it can predict potential faults such as pipeline ice crystal accumulation and local ice blockage, achieving early warning and proactive protection against ice blockage. Simultaneously, the quantitative detection data of this invention can be directly connected to the equipment's digital twin model, providing high-precision data support for ice slurry preparation process simulation, iterative optimization of operating conditions, visualization of operating status, and full life-cycle operation and maintenance, effectively promoting the transformation and upgrading of traditional ice slurry preparation equipment from passive operation to active control and intelligent operation and maintenance.

[0021] In summary, this invention achieves comprehensive technological breakthroughs in terms of detection structure, detection principle, working condition adaptation, and intelligent expansion. It solves many shortcomings of existing technologies, such as high pollution risk, limited observation conditions, poor detection accuracy, and low level of intelligence. It combines cleanliness, stability, accuracy, and scalability, and has extremely high engineering promotion value. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the non-contact ice slurry generation front position detection system based on the temperature field curvature of the cooling medium side as described in this invention; Figure 2 The cooling medium side temperature function curve and the corresponding signed temperature curvature curve are obtained by the non-contact ice slurry formation front position detection method based on the temperature field curvature of the cooling medium side as described in this invention. The markings in the diagram are as follows: 1. Heat exchanger; 2. Ice slurry flow channel; 3. Cooling medium flow channel; 4. Temperature sensor array; 5. Temperature acquisition module; 6. Processing module; 7. Control module; 8. Insulation layer; 9. Output and display module. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0024] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0025] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0027] The first aspect of this invention is to provide a non-contact method for detecting the position of the ice slurry formation front based on the curvature of the temperature field on the cooling medium side, comprising the following steps: S100: Acquire temperature measurement values ​​collected by multiple temperature sensors located on the cooling medium side of the heat exchanger; S200, based on multiple temperature measurements, construct a friction-smooth temperature function on the cooling medium side of the heat exchanger; S300, calculate the signed temperature curvature corresponding to each position within the temperature detection interval based on the smoothed temperature function along the path; S400, determine the extreme position of the signed temperature curvature in the preset curvature direction, and use the extreme position as an estimate of the position of the ice magma generation front.

[0028] As some examples of the present invention, after obtaining an estimated value of the position of the ice slurry formation front, the estimated value of the position of the ice slurry formation front can be used to realize the positioning and characterization of the ice slurry phase change region inside the heat exchanger.

[0029] Specifically, the estimated position of the ice slurry formation front obtained by the detection and calculation of this invention is a characteristic landmark position of the ice slurry phase change region. In actual production, it can effectively identify and locate the real area where the ice slurry phase change occurs inside the heat exchanger, and accurately reflect the actual distribution state of the solid-liquid phase change interval inside the heat exchanger.

[0030] In a preferred embodiment of the present invention, after acquiring temperature measurements from multiple temperature sensors, the original temperature measurements are first subjected to time-filtering preprocessing. Then, a smooth temperature function along the cooling medium side of the heat exchanger is constructed based on the filtered stable temperature data. This filters out random interference in temperature measurement caused by turbulence disturbances, sensor electrical noise, and instantaneous fluctuations in operating conditions during the two-phase flow of ice slurry and cooling medium. It eliminates disordered fluctuations and abrupt changes in the original temperature data, avoids false bending and local distortion of the temperature curve caused by directly fitting unfiltered original data, and ensures the time-series accuracy and stability of the temperature data. Simultaneously, the preprocessing filter significantly improves the accuracy of subsequent temperature function fitting, ensuring that the fitted temperature curve accurately reflects the actual temperature distribution of the cooling medium inside the heat exchanger, avoiding temperature field distortion caused by noise interference, and providing a reliable and clean data foundation for accurately solving the signed temperature curvature at each detection location. Furthermore, by using time filtering preprocessing, problems such as curvature calculation deviation and extreme point offset caused by temperature noise can be effectively avoided, reducing the misjudgment and omission of the ice slurry generation front position, significantly improving the positioning accuracy and detection stability of the ice slurry phase change front, ensuring the adaptability and reliability of the non-contact online detection method of this invention under complex ice slurry preparation conditions, and accurately restoring the true distribution state of the solid-liquid phase change region inside the heat exchanger.

[0031] As a preferred example of the present invention, after calculating the signed temperature curvature at each location using a smoothed temperature function along the flow path, the present invention establishes a unified axial coordinate determination system based on the flow direction of the cooling medium in the heat exchanger. Based on a preset curvature direction, it performs curvature extreme value retrieval within the effective detection range covered by the temperature sensor, determining the extreme value position of the signed temperature curvature in the preset curvature direction. Specifically, the present invention establishes a unified spatial reference by using the forward flow direction of the cooling medium as the positive direction of the axial coordinate. In this invention, by limiting the flow direction and the axial coordinate reference, the positive and negative attributes of the signed temperature curvature and the criteria for determining the bending trend can be unified, effectively avoiding the problem of misjudgment of extreme values ​​caused by chaotic coordinate references and directional judgment deviations. Simultaneously, by constraining the extreme value search range within the effective detection range of the sensor, it can avoid problems such as data fitting distortion at the equipment edge and interference from invalid extreme values ​​at the boundary, accurately selecting the curvature extreme value position corresponding to the inherent physical characteristics of the ice slurry phase change, ensuring that the finally locked ice slurry formation front position has uniqueness and accuracy, conforming to the actual working conditions of ice slurry nucleation, phase change, and ice crystal growth inside the heat exchanger.

[0032] As a specific example of the present invention, in the friction-smoothed temperature function curve, the flow direction of the cooling medium in the heat exchanger can be used as the x-axis and the temperature measurement value as the y-axis to construct a two-dimensional friction-smoothed temperature function curve; correspondingly, a two-dimensional signed temperature curvature curve and a signed temperature curvature function can be constructed using the flow direction of the cooling medium in the heat exchanger as the x-axis and the signed temperature curvature value as the y-axis, and the extreme value of curvature can be retrieved within the effective detection range covered by the temperature sensor to determine the extreme value position of the signed temperature curvature in the preset curvature direction.

[0033] Furthermore, it should be noted that the "non-contact" detection described in this invention refers to the temperature sensor not being in direct contact with the ice slurry or the liquid to be made into ice slurry. Preferably, the temperature sensor is positioned on the heat exchange wall between the ice slurry channel and the cooling medium channel, closer to the cooling medium, and isolated from the ice slurry channel.

[0034] As some examples of the present invention, multiple temperature sensors for collecting temperature measurements are arranged along the flow direction of the cooling medium in the heat exchanger. Specifically, the arrangement can be flexibly selected according to the heat exchanger structure and operating condition detection requirements, either with equal spacing or with non-equal spacing, to adapt to different equipment structures and detection accuracy requirements.

[0035] To further improve the detection accuracy of the ice slurry formation front, this invention preferably adopts a non-equidistant arrangement. Since ice slurry phase change and ice crystal formation are mainly concentrated in the region near the ice slurry formation front, this area exhibits dramatic temperature gradient changes and the most significant temperature curvature characteristics, making it the core critical area for ice slurry front location. Therefore, this region is designated as a preset key detection area. By densely deploying temperature sensors within this preset key detection area, with a spacing smaller than that of other conventional detection areas within the heat exchanger, the sampling density of the temperature field in the key phase change region can be effectively increased. This allows for accurate capture of subtle temperature changes and temperature curvature fluctuations near the front, avoiding missed detections and deviations in front location due to sparse sampling. Simultaneously, the non-equidistant arrangement reduces the number of sensors required in conventional stable temperature zones while ensuring high-precision positioning of the ice slurry formation front. This significantly improves the detection accuracy of phase change characteristic areas, ensures the reliability of algorithm recognition, and effectively reduces equipment modification costs and data processing volume, balancing detection accuracy and engineering practicality.

[0036] As examples of this invention, the temperature sensor used can be at least one of thermocouples, resistance temperature detectors (RTDs), thermistors, semiconductor temperature sensors, or fiber optic temperature sensors. The specific type can be flexibly selected based on the ice slurry preparation environment, temperature measurement accuracy requirements, and on-site installation conditions. All types of temperature sensors can achieve accurate real-time acquisition of the temperature along the cooling medium side, adapting to low-temperature, high-humidity, and fluid-turbulent ice slurry heat exchange conditions. They can stably output continuous and reliable temperature measurement data, providing accurate data input for subsequent temperature field construction, filtering, and temperature curvature calculation, effectively ensuring the accuracy and stability of the ice slurry formation front position detection.

[0037] As some examples of the present invention, the along-process smoothing temperature function can be constructed by two methods: spatial smoothing fitting or online state estimation based on a physical model. The specific method can be flexibly selected according to the actual working conditions, noise intensity, data accuracy requirements, and controller computing power.

[0038] Among them, the spatial smoothing fitting method can adopt any one or more combinations of smooth cubic spline fitting, local weighted regression fitting, Savitzky-Golay filter fitting, and piecewise polynomial fitting. It can continuously and smoothly process discrete temperature measurement data, effectively eliminate curve jitter caused by discrete sampling, and fit a continuous and differentiable temperature function along the path, laying a data foundation for high-precision first-order and second-order derivative solutions.

[0039] Online state estimation methods employ Kalman filtering, extended Kalman filtering, unscented Kalman filtering, or moving-time-domain estimation. Unlike pure data fitting methods, these methods also incorporate physical mechanisms such as the heat transfer law inside the heat exchanger, fluid flow characteristics, and energy conservation equations as process constraints. By combining measured temperature data with fusion correction, they can effectively suppress temperature measurement noise and model error interference, further improving the fitting accuracy and adaptability of the temperature function along the flow path. This approach is particularly suitable for dynamic fluctuation conditions such as variable load and variable flow rate.

[0040] As some examples of the present invention, the axial position and temperature value can be normalized before calculating the signed temperature curvature to improve the parameter transferability between devices with different pipe lengths or different temperature zones.

[0041] As a preferred example of the present invention, the signed temperature curvature satisfies the following calculation formula: ; in, Axial position The signed temperature curvature at that location, The positive or negative sign indicates the direction of curvature of the temperature curve along the cooling medium side; To construct the obtained friction-smooth temperature function, and These are the first and second derivatives of the smoothed temperature function along the path, respectively.

[0042] As examples of the present invention, the preset curvature direction can be the maximum or minimum value of the signed temperature curvature. For example, in a heat exchange system where the cooling medium gradually removes heat and the fluid cools down along the flow path, the strong heat absorption at the phase change front will cause the smooth temperature function curve along the flow path to exhibit a downward concave characteristic. Correspondingly, the signed temperature curvature curve will show a significant negative decrease, making the front position the minimum point of the signed temperature curvature across the entire field. Therefore, under the conventional ice-making conditions, the curvature direction can be directly preset to a negative minimum value, and the position of the ice-making front can be stably locked by searching. It should be noted that the axial coordinate in the present invention... The positive direction is defined as the direction of ice slurry flow, while the cooling medium flows in the opposite direction, forming a counter-current arrangement.

[0043] In other embodiments, the preset curvature direction can be predetermined based on the heat exchanger flow arrangement, axial coordinate direction, and temperature curve bending direction.

[0044] By pre-setting a curvature search direction that matches the physical characteristics of ice slurry phase change, this invention can uniquely, accurately, and interference-resistantly lock the position of the ice slurry generation front in a continuous axial curvature distribution. This avoids the shortcomings of traditional global optimization, which easily captures noise extrema, boundary extrema, and pseudo-extremes in flat areas. It significantly improves the stability and accuracy of front-end positioning under variable working conditions, low signal-to-noise ratio, and strong disturbance industrial conditions.

[0045] As some examples of the present invention, the non-contact ice slurry formation front position detection method based on the temperature field curvature of the cooling medium side of the present invention further includes: after obtaining an estimated value of the ice slurry formation front position, at least one of the cooling medium flow rate, ice slurry channel flow rate, cooling medium inlet temperature or refrigeration power can be adjusted based on the estimated value of the ice slurry formation front position.

[0046] This invention enables closed-loop linkage between detection and control. After accurately obtaining the estimated position of the ice slurry formation front, at least one operating parameter among the following can be adjusted based on the front offset state and phase change interval distribution: cooling medium flow rate, ice slurry channel flow rate, cooling medium inlet temperature, and system cooling power. By real-time correction of system operating conditions, the ice slurry formation front can be stably controlled within the optimal operating range, effectively suppressing problems such as pipe ice blockage, ice content fluctuations, and heat exchange efficiency degradation. This achieves precise, stable, and intelligent control of the ice slurry preparation process, significantly improving the system's continuous operation stability and cooling and cold storage performance.

[0047] A second aspect of the present invention is to provide a non-contact ice slurry formation front position detection system based on the curvature of the temperature field on the cooling medium side. The detection system employs the aforementioned detection method to detect the position of the ice slurry formation front. Figure 1 As shown, the detection system includes: Temperature sensor array 4 is set at multiple spatial locations on the cooling medium side of heat exchanger 1 for ice slurry preparation, and is used to collect the temperature at the corresponding locations; Temperature acquisition module 5 is used to acquire the temperature measurement value output by the temperature sensor array 4; Processing module 6 is used to perform time filtering on the temperature measurement value, construct a smooth temperature function along the path by spatial smooth fitting or online state estimation based on a physical model, calculate the signed temperature curvature, and identify the curvature extreme value within the detection range covered by the temperature sensor array 4 according to the cooling medium flow direction, axial coordinate definition and preset curvature direction to obtain an estimated value of the position of the ice slurry generation front. The output and display module 9 is used to output and display the estimated value of the position of the ice lava formation front or the ice lava formation status information.

[0048] As some specific examples of the present invention, the detection system of the present invention may selectively establish a communication connection with the external control module 7 to realize data uploading and closed-loop control.

[0049] As some specific examples of the present invention, the heat exchanger 1 can be a shell-and-tube heat exchanger, a spiral tube heat exchanger, a plate heat exchanger, or other indirect heat exchange structures.

[0050] The non-contact ice slurry formation front position detection method based on the temperature field curvature of the cooling medium side disclosed in this invention is applicable to ice slurry preparation heat exchange devices with independent ice slurry flow channels 2 and cooling medium flow channels 3. It can be widely adapted to various indirect heat exchange structures such as tubular heat exchangers, shell-and-tube heat exchangers, spiral tube heat exchangers, and plate heat exchangers. The equipment has wide adaptability and strong engineering portability.

[0051] As a preferred example of the present invention, the heat exchanger 1 has an ice slurry channel 2 and a cooling medium channel 3, which are separated by a heat exchange wall. The temperature sensor array 4 is arranged at intervals along the flow direction of the cooling medium in the heat exchanger 1 on the side of the heat exchange wall near the cooling medium channel 3, for collecting the temperature characterization values ​​of the heat exchange wall at different locations. The heat exchanger 1 is covered with a heat insulation layer 8 on the outside.

[0052] In a preferred embodiment of the present invention, a shell-and-tube heat exchanger 1 is used as the core heat exchange device. The inner tube's internal cavity forms an ice slurry channel 2, and the annular space formed by the outer wall of the inner tube and the inner wall of the outer tube forms a cooling medium channel 3. A temperature sensor array 4 is uniformly arranged along the axial direction of the outer wall of the inner tube and is positioned on the side of the heat exchange wall closest to the cooling medium channel 3. By collecting the temperature characterization values ​​of the heat exchange wall at each axial position, the phase change heat transfer state on one side of the ice slurry channel 2 is indirectly reflected. This eliminates the risk of medium contamination without intruding into the ice slurry fluid, meeting the requirements of high-cleanliness applications such as food and medical applications. Simultaneously, an insulation layer 8 is fully covered on the outer side of the outer tube of the heat exchanger 1, effectively isolating the interference of ambient air convection and ambient temperature fluctuations on the internal heat transfer process, significantly reducing cold loss, and avoiding temperature measurement noise and temperature field distortion caused by external environmental disturbances. This ensures that the temperature data collected by the temperature sensor array 4 accurately reflects the internal phase change heat transfer conditions of the device, further improving the accuracy and stability of the detection of the ice slurry formation front.

[0053] In a preferred embodiment of the present invention, the temperature sensor array 4 uses a T-type thermocouple and is equipped with a multi-channel thermocouple temperature acquisition module 5 with cold junction compensation function to acquire temperature data, which can effectively eliminate the system measurement error caused by the cold junction temperature deviation of the thermocouple and ensure the acquisition accuracy of the original temperature data.

[0054] As a preferred embodiment of the present invention, the temperature sensor should be installed close to the side of the heat exchange wall near the cooling medium flow channel 3, and the temperature sensor and the heat exchange wall should be tightly thermally coupled by any one of the thermally conductive media such as thermal grease, thermal adhesive, and thermal pad, which can effectively reduce the contact thermal resistance, ensure that the temperature collected by the temperature sensor can accurately match the actual temperature of the pipe wall, and avoid temperature measurement lag and numerical deviation caused by contact gap.

[0055] Furthermore, the present invention adds a heat insulation and protection structure to the outside of the temperature sensor, which, together with the heat insulation layer 8 on the outside of the heat exchanger 1 body, can isolate the heat dissipation interference caused by ambient air convection and ambient temperature fluctuations to the greatest extent, and reduce the influence of external operating conditions on the temperature measurement results.

[0056] To further offset temperature measurement errors and improve detection accuracy, this invention relies on the thermally conductive coupling medium layer of the temperature sensor, an external insulation structure, and a pre-calibrated and trained heat transfer compensation model to systematically correct temperature deviations caused by pipe wall thermal hysteresis and environmental heat dissipation losses. Simultaneously, based on actual operating conditions, at least one of the following data correction processes can be selectively applied to the original temperature measurement values: thermal inertia compensation, environmental heat dissipation compensation, pipe wall thermal conductivity compensation, and reference operating condition deviation compensation. This eliminates interference from installation structure, heat transfer characteristics, environmental disturbances, and equipment operating condition deviations. The high-precision temperature data after multiple corrections is then used to construct a smooth temperature function along the flow path, ensuring the authenticity and accuracy of the temperature field distribution from the data source. This provides reliable data support for subsequent precise calculation of temperature curvature and high-precision positioning of the ice slurry formation front, significantly improving the stability and adaptability of the detection method under complex industrial conditions.

[0057] The following specific embodiments illustrate the non-contact ice slurry formation front position detection method and system based on the temperature field curvature of the cooling medium side described in this invention: The non-contact ice slurry formation front position detection system based on the temperature field curvature of the cooling medium side, such as Figures 1-2 As shown, the device includes a temperature sensor array 4, a temperature acquisition module 5, a processing module 6, and an output and display module 9, which are communicatively connected to a control module 7. The heat exchange device includes a heat exchanger 1, an ice slurry channel 2, a cooling medium channel 3, and an insulation layer 8.

[0058] In this embodiment, the heat exchange device is a shell-and-tube heat exchanger. The ice slurry channel 2 is formed inside the inner tube, and the cooling medium channel 3 is formed in the annular space between the outer wall of the inner tube and the inner wall of the outer tube. The temperature sensor array 4 is arranged axially along the outer wall of the inner tube and is set on the side of the heat exchange wall close to the cooling medium between the ice slurry channel 2 and the cooling medium channel 3 to obtain the temperature characterization value of the heat exchange wall at different axial positions. An insulation layer 8 is provided on the outer side of the outer tube.

[0059] Since the ice slurry formation front is more likely to be located near the ice slurry outlet under preset operating conditions, the spatial density of temperature sensors is increased in this area to improve the positioning resolution of the ice slurry formation front. In one embodiment, the effective length of the shell-and-tube heat exchanger is 8m, and 16 temperature sensors are installed in a non-equidistant arrangement: the sensor spacing in the preset key detection zone near the ice slurry outlet is smaller than the sensor spacing in other areas. The specific sensor locations are 0.00m, 1.00m, 2.00m, 3.00m, 4.00m, 5.00m, 5.30m, 5.60m, 5.90m, 6.20m, 6.50m, 6.80m, 7.10m, 7.40m, 7.70m, and 8.00m. The temperature measurement points at the inlet and outlet boundaries (z=0.00m and z=8.00m) are not involved in curvature extremum retrieval; the remaining sensors are used for front positioning.

[0060] Among them, temperature acquisition module 5 acquires temperature data according to a preset period to form a discrete temperature sequence: ; in, For the first The location corresponding to each temperature sensor For the first Temperature values ​​at each sampling time. This refers to the number of temperature sensors. Next, processing module 6 first performs time filtering, for example, using exponential smoothing: ; in, This is the filtered temperature value. The smoothing coefficient is used; the time filtering can also employ at least one of moving average filtering or Kalman filtering.

[0061] Subsequently, a smoothed temperature function is constructed based on the filtered temperature values ​​at each location. This smoothed temperature function can be obtained through spatial smoothing fitting, including at least one of smoothed cubic spline fitting, locally weighted regression fitting, Savitzky-Golay filtering fitting, or piecewise polynomial fitting. for: , )}; In other embodiments of the invention, the smoothed temperature function along the path can also be obtained through online state estimation based on a physical model.

[0062] Furthermore, the signed temperature curvature was calculated. for: ; in, Axial position The signed temperature curvature at that location, The positive or negative sign indicates the direction of curvature of the temperature curve along the cooling medium side; To construct the obtained friction-smooth temperature function, and These are the first and second derivatives of the smoothed temperature function along the path, respectively, and the signed curvature. The extreme value in the preset curvature direction corresponds to the position where the temperature curve bends downward most sharply, that is, the negative minimum value.

[0063] Under the current coordinate direction and the cooling medium flow direction, processing module 6 determines the position where the signed temperature curvature reaches its minimum value within the detection interval as the estimated position of the ice slurry formation front: .

[0064] In some embodiments of the present invention, thermal inertia, environmental heat dissipation, or pipe wall thermal conductivity compensation can be applied to the temperature measurement values, and the stability of the leading edge position estimation can be improved by combining the temporal continuity of the leading edge position, measurement point anomaly diagnosis, or reliability evaluation.

[0065] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A non-contact method for detecting the position of the ice slurry formation front based on the curvature of the temperature field on the cooling medium side, characterized in that, include: Acquire temperature measurements from multiple temperature sensors located on the cooling medium side of the heat exchanger; Based on multiple temperature measurements, a friction-smooth temperature function is constructed on the cooling medium side of the heat exchanger. The signed temperature curvature at each position within the temperature detection interval is calculated based on the aforementioned smoothed temperature function along the path. The extreme position of the signed temperature curvature in the preset curvature direction is determined, and this extreme position is used as an estimate of the position of the ice magma formation front.

2. The non-contact ice slurry formation front position detection method based on the curvature of the temperature field on the cooling medium side according to claim 1, characterized in that, After acquiring temperature measurements from multiple temperature sensors, the raw temperature measurements are preprocessed with time filtering, and then a smooth temperature function along the cooling medium side of the heat exchanger is constructed based on the filtered stable temperature data.

3. The non-contact ice slurry formation front position detection method based on the temperature field curvature on the cooling medium side according to claim 1, characterized in that, After calculating the signed temperature curvature at each location using the along-the-path smoothing temperature function, an axial coordinate determination system is established based on the flow direction of the cooling medium in the heat exchanger. Based on the preset curvature direction, the extreme value of curvature is retrieved within the effective detection range covered by the temperature sensor to determine the extreme value position of the signed temperature curvature in the preset curvature direction.

4. The non-contact ice slurry formation front position detection method based on the temperature field curvature on the cooling medium side according to claim 1, characterized in that, The multiple temperature sensors are arranged at equal or non-equal intervals along the flow direction of the cooling medium in the heat exchanger.

5. The non-contact ice slurry formation front position detection method based on the temperature field curvature on the cooling medium side according to claim 4, characterized in that, The multiple temperature sensors are arranged at non-equidistant intervals along the flow direction of the cooling medium in the heat exchanger. The spacing between the temperature sensors in the preset key detection area is smaller than that in other areas. The preset key detection area includes at least the operating range within the heat exchanger near the ice slurry formation front.

6. The non-contact ice slurry formation front position detection method based on the curvature of the temperature field on the cooling medium side according to claim 1, characterized in that, The smoothed temperature function along the path is obtained through spatial smoothing fitting or online state estimation based on a physical model.

7. The non-contact ice slurry formation front position detection method based on the temperature field curvature on the cooling medium side according to claim 1, characterized in that, The signed temperature curvature satisfies the following calculation formula: ； in, Axial position The signed temperature curvature at that location, The positive or negative sign indicates the direction of curvature of the temperature curve along the cooling medium side; To construct the obtained smooth temperature function along the path, and These are the first and second derivatives of the smoothed temperature function along the path, respectively.

8. The non-contact ice slurry formation front position detection method based on the temperature field curvature on the cooling medium side according to claim 1, characterized in that, The detection method further includes: After obtaining an estimate of the position of the ice slurry formation front, at least one of the following is adjusted based on the estimate: cooling medium flow rate, ice slurry channel flow rate, cooling medium inlet temperature, or cooling power.

9. The non-contact ice slurry formation front position detection method based on the curvature of the temperature field on the cooling medium side according to claim 1, characterized in that, The location of the minimum value of the signed temperature curvature in the negative direction is determined, and the location of this minimum value is used as an estimate of the location of the ice magma formation front.

10. A non-contact ice slurry formation front position detection system based on the curvature of the temperature field on the cooling medium side, wherein the detection system uses the detection method described in any one of claims 1 to 9 to detect the ice slurry formation front position, and the detection system comprises: A temperature sensor array (4) is set at multiple spatial locations on the cooling medium side of the heat exchanger (1) for ice slurry preparation, and is used to collect the temperature at the corresponding locations; Temperature acquisition module (5) is used to acquire the temperature measurement value output by the temperature sensor array (4); The processing module (6) is used to calculate an estimated value of the position of the ice magma formation front based on the temperature measurement value; The output and display module (9) is used to output and display the estimated value of the position of the ice lava formation front or the ice lava formation status information.

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