Precise temperature control fluid heating system based on vortex tube cooling

Abstract

The invention relates to the technical field of fluid heating temperature control, and discloses a precise temperature control fluid heating system based on vortex tube cooling, which comprises a reference temperature sensor and a disturbance temperature sensor which are arranged in series along a flow channel, a micro vortex tube arranged at the downstream and an acoustic sensor arranged at an exhaust port of the micro vortex tube, the control unit controls the micro vortex tube in a feedforward mode according to a temperature difference signal of the temperature sensor, and corrects a control time sequence online through a signal of the acoustic sensor, the upstream temperature difference change serves as a feedforward signal of thermal disturbance to be used for pre-judging and instantaneously counteracting the thermal disturbance, and then the control mode depending on lagging feedback is changed; therefore, control oscillation caused by thermal inertia is avoided, and online self-adaptive adjustment of fluid state changes is achieved by utilizing accompanying information of the actuator.

Description

TECHNICAL FIELD

[0001] The present application relates to a precise temperature control fluid heating system based on vortex tube cooling, belonging to the technical field of fluid heating temperature control. BACKGROUND

[0002] When the current application scene puts forward higher requirements for the dynamic response and precision of temperature control, for example, in the precise injection molding process, the rapid change of external load will frequently cause instantaneous fluctuations in fluid temperature, at this time the internal limitations of the above technical methods begin to appear, the reason is that the thermal inertia of the fluid itself causes any control instruction to be delayed in time, the heating action of the heating unit and the cooling action of the refrigeration unit often conflict with each other, and the compensation instructions issued by the control system based on the lagged temperature information itself will become a new disturbance source, causing the system temperature to oscillate around the target value.

[0003] A direct improvement idea is to further improve the response speed of the control system and the power of the execution element, but this will intensify the energy offset between heating and refrigeration actions, and amplify the amplitude of control overshoot, while also increasing the cost of equipment and operating energy consumption.

[0004] Analysis shows that the existing technical methods mainly have the following deficiencies, such as the execution lag of control action behind the actual occurrence of thermal disturbance, the system can only compensate for the temperature deviation that has been formed, but cannot suppress at the disturbance source; the control system lacks online perception of changes in the physical properties of the fluid, when the viscosity or flow rate of the fluid changes, the original control model is no longer accurate. Therefore, how to build a fluid heating system that can predict and instantaneously offset thermal disturbances, while also online sensing fluid state changes to adaptively adjust the control logic, has become a technical problem to be solved by the present application. SUMMARY

[0005] The present application provides a precise temperature control fluid heating system based on vortex tube cooling, which mainly aims to solve the problem that the existing technology cannot predict and offset thermal disturbances due to thermal inertia lag, and cannot online perceive fluid state changes to adaptively adjust the control logic.

[0006] To achieve the above purpose, the present application provides a precise temperature control fluid heating system based on vortex tube cooling, which comprises: a flow channel arranged along the flow direction of the fluid, a reference temperature sensor arranged at the upstream section of the flow channel, and a disturbance temperature sensor arranged downstream of the reference temperature sensor; a quenching zone arranged downstream of the disturbance temperature sensor, the quenching zone being provided with a micro vortex tube; and an acoustic sensor arranged at the exhaust port of the micro vortex tube; The control unit is connected with the reference temperature sensor, the perturbation temperature sensor, the micro vortex tube and the acoustic sensor, and the system stores a gradient threshold value and an initial transit time representing heat flow from the perturbation temperature sensor position to the quench zone position; the control unit is configured to: calculate a temperature difference between the temperature readings of the reference temperature sensor and the perturbation temperature sensor; determine a transit time correction parameter based on the acoustic characteristics of the exhaust noise collected by the acoustic sensor; and when the absolute value of the temperature difference exceeds the gradient threshold value, the control unit determines a quench control instruction based on the temperature difference, the initial transit time and the transit time correction parameter, and outputs the quench control instruction to the micro vortex tube.

[0007] Preferably, the system stores a mapping relationship between the acoustic characteristics and the transit time correction parameter; the control unit is configured to determine the transit time correction parameter based on the acoustic characteristics of the exhaust noise collected by the acoustic sensor, including: the control unit collects the sound pressure signal of the exhaust noise in a predetermined frequency band, and calculates the spectral entropy value of the sound pressure signal as the acoustic characteristics; and the control unit determines the transit time correction parameter corresponding to the spectral entropy value based on the mapping relationship.

[0008] Preferably, a passive phase change energy storage section is further provided downstream of the quench zone; the system further stores a rate threshold value; the control unit is further configured to: periodically control the micro vortex tube to inject a cold gas flow pulse with a fixed duration to the phase change energy storage section; and based on the temperature response curve collected by the perturbation temperature sensor after the injection of the cold gas flow pulse, calculate the temperature recovery rate of the temperature response curve; and when the absolute value of the temperature recovery rate is less than the rate threshold value, the control unit increases the gain coefficient on which it determines the quench control instruction; wherein, the absolute value of the temperature recovery rate is , and the rate threshold value is .

[0009] Preferably, the quench control instruction includes an opening instruction of the micro vortex tube and duration information representing the duration of the cold gas flow injection.

[0010] Preferably, the control unit determines the duration information in a positive correlation with the absolute value of the temperature difference.

[0011] Preferably, the micro vortex tube is connected to a compressed air pipeline, and the compressed air pipeline is in communication with an existing compressed air source of a place where an industrial equipment carrying the system is located.

[0012] Preferably, the reference temperature sensor and the perturbation temperature sensor are both infrared temperature sensors.

[0013] Preferably, the system further comprises a gas guide pipeline, one end of which is in communication with the cold air outlet of the micro vortex tube, and the other end is open in front of the lens of the infrared temperature sensor, so as to form a gas curtain for isolating external environment water vapor.

[0014] Preferably, the system further stores a frequency threshold value; the control unit is further configured to analyze the frequency of the interference pulse formed by the residual water vapor penetrating the gas curtain in the signal of the infrared temperature sensor; and when the frequency of the interference pulse exceeds the frequency threshold value, the control unit further increases the intensity of the cold air flow ejected by the micro vortex tube corresponding to the quenching control instruction when determining the quenching control instruction.

[0015] Preferably, the phase change energy storage section comprises a sandwich structure encapsulating a phase change material, and the phase change material is infiltrated and compounded with a heat-conducting metal skeleton material having a three-dimensionally interconnected honeycomb-shaped microporous structure.

[0016] Compared with the prior art, the present application has the following advantages: 1、The present application sets up a reference temperature sensor and a disturbance temperature sensor in series in the upstream section of the flow channel, and uses the temperature difference between the two as a feedforward signal for triggering the action of the micro vortex tube in the downstream quenching section, thereby establishing a control relationship of thermal disturbance pre-judgment and immediate offset. This method changes the operation basis of the traditional temperature control system which relies on lagging feedback for compensation, so that the system is no longer passively dealing with the temperature deviation that has already spread out, but neutralizes the excess energy carried by the thermal disturbance at the beginning, thereby avoiding the problems of control oscillation and overshoot caused by fluid thermal inertia, and making the whole temperature control process more rapid and smooth.

[0017] 2、The present application combines the acoustic sensor arranged at the exhaust port of the micro vortex tube and the control logic for processing the signal to correct the transit time online, forming a passive sensing and adaptive regulation loop for the internal state of the fluid. It uses the exhaust noise generated by the vortex tube during operation as an information carrier, correlates its acoustic characteristics with the actual flow state of the fluid which affects the key parameters of the transit time, so that the system can cope with the change of flow rate caused by the aging of the fluid or the change of working conditions without increasing the invasive flow meter or viscosity meter, ensuring the timing accuracy of the feedforward offset action and improving the reliability of the system under long-term operation and complex working conditions.

[0018] 3、The application establishes an online self-calibration mechanism for key functional materials by periodically applying a short cold airflow pulse to the rear phase change energy storage section of the micro vortex tube, and evaluating the actual working state of the phase change material according to the temperature recovery characteristics collected by the disturbance temperature sensor. This mechanism converts the performance decline of the phase change material caused by physical hysteresis effect from an invisible risk factor into an internal state parameter that can be quantitatively evaluated and used to adjust the system control gain, enabling the system to compensate for performance fluctuations in the phase change material and maintain the control accuracy and stability of the overall scheme. Additionally, the dry cold airflow generated during the operation of the micro vortex tube is guided to the front of the infrared temperature sensor lens through the added air guide pipeline to form an air curtain. This design not only solves the engineering problem of external interference in infrared temperature measurement in high humidity environments by utilizing the byproduct of the system itself, but also further uses the residual water vapor interference pulse frequency that penetrates the air curtain as an auxiliary judgment basis for representing the degree of temperature change. This way of converting negative external interference factors into enhanced and supplemented main control logic through physical isolation and information reinterpretation expands the system's applicability to harsh industrial environments. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 The system architecture schematic diagram of the precise temperature control fluid heating system based on vortex tube cooling according to the present application is shown in the figure. Fig. 2 The comparison chart of the control strategy's effect on heat disturbance suppression according to the present application is shown in the figure. Fig. 3 The functional block diagram of the adaptive feedforward control algorithm according to the present application is shown in the figure. DETAILED DESCRIPTION

[0020] To make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described in detail below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0021] The precise temperature control fluid heating system based on vortex tube cooling disclosed in the present application mainly includes a flow channel arranged along the fluid flow direction, a group of temperature sensor units, a quenching zone and a control unit connected with each component arranged in series along the flow channel. The temperature sensor unit includes a reference temperature sensor (1) arranged in the upstream section and a disturbance temperature sensor (2) arranged downstream thereof. ​), a micro vortex tube is arranged in the quenching zone, and an acoustic sensor is further arranged at the exhaust port of the micro vortex tube, and the operation logic is that the control unit takes the temperature difference collected by the two temperature sensors as a feedforward signal to predict and trigger the instantaneous cooling action of the downstream micro vortex tube, and meanwhile, the exhaust noise characteristics collected by the acoustic sensor are used to correct the response timing of the feedforward control online; in some industrial scenes with high requirements for fluid temperature control accuracy, such as precision injection molding process, the instantaneous temperature fluctuation of the heat transfer medium due to the change of external loads such as switch mode is a key factor affecting the yield of products, and the thermal inertia of the fluid itself makes it difficult for the traditional control method based on lagging feedback to effectively suppress such fluctuations; to cope with this challenge, the system is configured to perform a heat disturbance feedforward quenching procedure, the control unit continuously collects the readings of the reference temperature sensor ( ) and the disturbance temperature sensor ( ) at a high frequency, and calculates the temperature difference between the two in real time , wherein and are physically spaced apart and pre-calibrated to correspond to a preset travel time of the fluid at a nominal flow rate; the system stores a gradient threshold value, which is set according to the value that is higher than the measurement noise floor of the temperature sensor itself but lower than the minimum disturbance energy that may cause defects in the final product, for example, it can be set to 0.2°C, when the control unit determines that the absolute value of the temperature difference exceeds the gradient threshold value, it is determined that a heat disturbance has passed and reached ; at this time, the control unit takes the occurrence of as a feedforward trigger signal, determines the quenching control instruction based on the size of and a preset initial transit time, and outputs the instruction to the micro vortex tube in the downstream quenching zone, the quenching control instruction includes the opening instruction of the micro vortex tube and the time length information representing the duration of the jet cold air flow, wherein the time length information is proportional to the absolute value of the temperature difference , and the vortex tube jets a millisecond-level low-temperature air flow after receiving the instruction, which offsets the excess heat carried by the heat disturbance fluid group at the moment it arrives; in this way, by taking the temperature difference change upstream as the feedforward signal of the downstream actuator, the system intervenes in the disturbance propagation path before the heat disturbance spreads and affects the downstream process, thereby helping to avoid control oscillation and overshoot caused by thermal inertia.

[0022] In an industrial operating environment, the physical properties of the fluid, especially the viscosity, will change due to aging or temperature changes, which directly leads to changes in the actual flow rate of the fluid, and in turn causes the transit time parameter on which the control unit makes a feedforward prediction to deviate, which may cause the quenching action to be too early or too late. In view of this, the system also sets up an adaptive control loop for passive sensing of the fluid state, which is composed of an acoustic sensor arranged at the exhaust port of the micro vortex tube and the corresponding control logic. Changes in the viscosity of the fluid will affect its heat exchange efficiency with the pipe wall, and this change will be transmitted to the vortex tube and change its working back pressure, ultimately causing regular changes in the acoustic characteristics of its exhaust noise. To utilize this physical correlation, the system is configured to synchronously collect the exhaust noise signal of the vortex tube at each time it performs a quenching task, by the acoustic sensor. The control unit processes the collected sound pressure signal, for example, calculates the spectral entropy value in a certain predetermined frequency band as the acoustic feature representing the current fluid state. The selection of the predetermined frequency band can be calibrated through offline experiments to obtain a frequency response interval that is sensitive to changes in flow rate. The system has a pre-stored mapping relationship between the acoustic feature and the transit time correction parameter, which can be established through a one-time calibration experiment, i.e. changing the fluid flow rate under controlled conditions and recording the corresponding spectral entropy value at each flow rate, thereby generating a lookup table or fitting function. In real-time operation, the control unit determines a transit time correction parameter by querying the mapping relationship according to the calculated spectral entropy value, and uses the correction parameter to adjust the initial transit time. Finally, the control unit generates and issues a quenching control instruction based on the corrected transit time. Through this mechanism, the system uses the accompanying information during the operation of the actuator to perceive the state changes of the working medium, realizes online closed-loop adaptive adjustment of the timing parameters of the feedforward control core, and improves the timing accuracy of the feedforward compensation action when the fluid state changes.

[0023] To further smooth the residual energy fluctuations that may exist after the quenching operation, a passive phase change energy storage section can be arranged downstream of the quenching zone. The energy storage section may, for example, adopt a sandwich structure encapsulating a phase change material, wherein the phase change material is infiltrated and compounded with a heat-conducting metal skeleton material with a three-dimensionally connected honeycomb-like micro-porous structure to improve its thermal conductivity. The inherent phase change hysteresis physical property of the phase change material at high frequency may cause its heat absorption and release capacity to decrease at certain times, which becomes a factor that may restrict performance. To avoid this risk, the system is also configured to perform an online calibration mechanism for the working state of the functional material. The control unit is configured to periodically control the micro vortex tube to inject a cold gas pulse with a fixed duration and small energy as a probe signal into the phase change energy storage section. At the same time, the control unit calculates the temperature recovery rate of the temperature response curve collected by the disturbance temperature sensor immediately upstream ; since the phase change material in the ideal phase change interval responds gently to temperature disturbance due to latent heat effect, while the phase change material in the hysteresis failure zone responds more quickly, the temperature recovery rate can reflect the actual working state of the phase change material at that time; the system stores a rate threshold , when the control unit determines that the absolute value of the temperature recovery rate is less than the rate threshold, that is , indicating that the buffering capacity of the phase change material decreases, at this time, the control unit will automatically increase an internal gain coefficient on which it depends when determining the quenching control instruction, to appropriately strengthen the intensity of active quenching, to compensate for the temporary attenuation of passive buffering capacity; this design converts the internal working state of a functional material from an invisible factor to a quantifiable evaluation and closed-loop compensation control parameter, to maintain the control precision stability of the system as a whole.

[0024] In addition, in some applications, to achieve non-contact measurement, the reference temperature sensor and the disturbance temperature sensor can be selected as infrared temperature sensors, but in a high humidity environment, water vapor can interfere with the infrared signal; therefore, the system can further include a gas guide pipeline, one end of the pipeline is in communication with the cold gas outlet of the micro vortex tube, and the other end is open in front of the lens of the infrared temperature sensor; when the system is running, the dry cold gas flow generated by the vortex tube is guided by the pipeline to form a continuous air curtain in front of the sensor lens, which can physically isolate most of the water vapor in the external environment to ensure the effectiveness of the temperature measurement signal; even so, when the working condition changes drastically, a large amount of steam is generated instantaneously, and a small amount of steam clusters can still penetrate the air curtain and form a short-term interference pulse on the sensor signal, the system further utilizes this interference as a kind of information, and the control unit is configured to analyze the frequency of the occurrence of the interference pulse, because the pulse frequency is related to the degree of steam generation; the system stores a frequency threshold, when the control unit detects that the frequency of the interference pulse exceeds the frequency threshold, it is determined that the system is in a state of relatively severe disturbance, and accordingly, when determining the quenching control instruction, the intensity of the cold gas flow ejected by the micro vortex tube corresponding to the instruction is further increased; this way of converting environmental interference through physical isolation and information reinterpretation into auxiliary and supplement to the main control logic expands the applicability of the system to specific industrial environments.

[0025] Example 1: In a precision injection molding unit for producing high-precision optical lenses, the technical solution of the present application is deployed to control the temperature of the heat transfer fluid in the mold cooling channels. When the unit is re-injected with a batch of heat transfer oil whose physical properties differ from the old oil after a routine maintenance is completed, the system operates as follows: Because the actual viscosity of the new oil at working temperature is higher than that of the old oil, the actual flow rate of the fluid in the pipeline decreases compared to before maintenance under the condition that the output pressure of the circulating pump group remains unchanged, and then the thermal disturbance from the reference temperature sensor position flows to the disturbance temperature sensor position, and the time from the position to the quenching zone is also correspondingly extended; after the injection molding machine performs a mold opening and closing cycle, causing a transient rise in the temperature of the backflow oil, the control unit calculates that the absolute value of the temperature difference exceeds the preset gradient threshold value, and triggers a feedforward quenching task; at the same time when the control unit calculates the required quenching energy and instructs the micro vortex tube to open according to the value, the acoustic sensor arranged at the exhaust port of the micro vortex tube also starts to collect the acoustic signals of the exhaust noise; because the decrease in fluid flow rate changes the heat exchange conditions of the pipe wall, and then affects the working back pressure and temperature difference of the vortex tube, causing the spectral characteristics of its actual exhaust noise to change, the control unit obtains a different acoustic feature reading by calculating the spectral entropy value of the sound pressure signal; the control unit then indexes the spectral entropy value to find a corresponding transit time correction parameter in the mapping relationship between the acoustic features and the transit time correction parameters stored in the system memory; the correction parameter is used to extend the original initial transit time of the system, so that the timing of the final generated quenching control instruction is correspondingly delayed; this series of online correction calculations and decisions is completed within milliseconds, and the result is that the cold gas jetted by the micro vortex tube is synchronized with the actual arrival time of the heat disturbance fluid group at the quenching zone, so that the excess heat energy carried by it is offset.

[0026] In this process, the system does not rely on independent flow meters or viscometers to perceive the changes in the physical properties of the fluid, but instead converts the acoustic accompanying information generated by the micro vortex tube, which is the actuator of the feedforward quenching action, into the basis for modifying the core timing parameters of the feedforward action itself; the active quenching mechanism and the acoustic adaptive adjustment mechanism form a cooperative working loop, the former provides the signal source for the latter to analyze, and the latter calibrates the accuracy of the timing for the former when the working condition changes; the traditional control method faces the situation of either control failure due to the inability to perceive the flow rate change or the need to increase additional sensors to make up for it, while the technical solution solves this situation by reusing information within the system in a single architecture; it does not directly measure the flow rate variable of the fluid, but establishes a correlation between noise characteristics and transit time, so that the system control logic can directly respond to the final impact of flow rate changes, i.e. the change of transit time, and the stress detection results of the batch of optical lenses produced subsequently are at the same level as before maintenance, without defects caused by temperature fluctuations.

[0027] Example 2: To objectively verify the adaptive ability of the technical solution of the present application in response to instantaneous thermal disturbance and changes in the physical properties of the working medium, a closed-loop fluid temperature control test platform is built; the platform includes a standard heat exchange circuit, a controllable power pulse heat source, and the system of the present application as the measured object, and a traditional PID controller and an independent heating and refrigeration unit are configured as a control group; the pulse heat source is used to simulate the repeatable stepwise thermal disturbance introduced by rapid changes in load in industrial applications, and the pulse energy is set to balance the authenticity and distinguishability of the test, and the energy value is set to be equivalent to the heat change generated by the switching mode in a typical injection molding cycle, specifically 500W power heating for 2 seconds; in the test, an independent and calibrated high-precision temperature recorder is set at the final output end of the circuit to monitor and record the actual temperature response curve of each group under disturbance.

[0028] The test is divided into two groups, the first group is to verify the suppression effect of the thermal disturbance feedforward quenching mechanism, and the second group is to verify the effect of the acoustic adaptive regulation loop when the fluid viscosity changes; in the first group of tests, the heat transfer oil with standard viscosity is used, the circuit temperature is first stabilized at a reference value of 80.0°C, then the heat pulse set is injected into the fluid, and the outlet temperature changes of the system of the present application and the traditional PID control system within 60 seconds after the disturbance are recorded respectively; in the second group of tests, the oil in the circuit is replaced with oil of the same type with a viscosity 20% higher, and the above test steps are repeated, and a control group B is added which only opens the feedforward quenching but closes the acoustic adaptive adjustment function, to isolate and verify the effectiveness of the adaptive function; the key values of the collected data are shown in Table 1.

[0029] Table 1: Comparison of temperature response data under different control modes and working conditions.

[0030]

[0031] As can be seen from the data in Table 1, under standard viscosity oil, the outlet temperature of control group A showed a peak overshoot of more than 2°C after the disturbance and was accompanied by continuous oscillation. It failed to recover stability within the 60-second observation period. This phenomenon is consistent with the characteristic of PID control mode based on hysteresis feedback compensation. The temperature fluctuation of the experimental group was suppressed within 0.3°C and recovered stability within a few seconds. This result corresponds to the operation of the thermal disturbance feedforward quenching mechanism, that is, by The prediction of the signal offsets the energy carried by the thermal disturbance before it reaches the outlet; after changing to high-viscosity oil, the peak temperature fluctuation of control group B increased to 1.2°C, indicating that the fixed transit time parameter was inconsistent with the actual situation due to the slowdown in flow rate, resulting in the failure of the feedforward quenching pulse to synchronize with the thermal disturbance; while the temperature fluctuation of the experimental group under this working condition was not significantly different from that under standard viscosity. The reduction in this difference is attributed to the intervention of its acoustic adaptive control loop. Through online analysis of the vortex tube exhaust sound pattern, the change in fluid state was judged and the transit time parameter was compensated, thereby maintaining the timing accuracy of the feedforward control.

[0032] Example 3: This example combines Figs. 1 to 3 , a precision temperature-controlled fluid heating system based on vortex tube cooling is described, such as Fig. 1 As shown in the figure, the working process of the system starts with the fluid input, and the fluid passes through the reference temperature sensor located upstream in the flow direction. With disturbance temperature sensor ,in Used to measure the inlet reference temperature, Used to identify thermal disturbances entering upstream, the temperature difference signal generated by the two sensors It is sent to the control unit as a feedforward trigger signal. The control unit performs thermal disturbance feedforward quenching and adaptive adjustment according to the signal, and generates a quenching control instruction. The instruction contains opening and duration information to control the micro vortex tube in the downstream quenching zone to perform instantaneous cooling action to offset thermal disturbance. When the micro vortex tube is working, the acoustic sensor at its exhaust port will collect the exhaust noise of the vortex tube and transmit the noise accompanying information to the control unit. The control unit extracts acoustic characteristics such as spectral entropy value from it to correct the transit time parameters online, thereby ensuring the timing accuracy of the quenching action. The fluid processed in the quenching zone further flows through the passive phase change energy storage section. The energy storage section uses the latent heat effect of the phase change material to further smooth the residual temperature fluctuations. The control unit also periodically detects pulses and analyzes their temperature recovery rate. , to evaluate the phase change material state and adjust the control gain online, finally, the system obtains stable temperature control fluid from the output end.

[0033] As shown in Fig. 2 , the horizontal axis of the graph is time in seconds, and the vertical axis is temperature in °C. The three curves represent the temperature changes of the system of the present application (solid line), the traditional PID control (long dashed line), and the uncontrolled reference point line (dotted line), respectively. As can be seen from the graph, when the initial temperature is stabilized at 80.0°C, a same thermal disturbance is applied. The temperature of the uncontrolled reference system rises sharply and then cools slowly naturally. The traditional PID control system shows significant lag and overshoot, with a temperature peak of about 82.1°C and subsequent sustained oscillation, which is still not completely stable within 60 seconds of observation time. The temperature response of the system of the present application shows very small fluctuations, with the peak temperature effectively suppressed at about 80.3°C, and quickly returns to the set temperature in about 4.5 seconds without significant oscillation. This verifies that the system of the present application, through the combination of feedforward quenching and adaptive adjustment, can effectively avoid the control oscillation problem caused by thermal inertia.

[0034] As shown in Fig. 3 , first, the temperature sensing unit , provides real-time temperature readings, based on which module 1.0 calculates the disturbance temperature difference ; this signal is transmitted to module 2.0, which is responsible for generating the feedforward quenching instruction and sending it to the micro vortex tube as the actuator. The generation of the instruction not only depends on the size of , but also depends on a core timing parameter, i.e., the transit time parameter stored in database D1. To ensure the accuracy of this timing parameter, the system introduces an adaptive correction loop. The exhaust noise signal collected by the acoustic sensor is sent to module 3.0, which calculates the transit time correction parameter by analyzing the signal characteristics and updates the transit time in database D1 online with this parameter, so that module 2.0 can generate the quenching instruction based on the more accurate corrected transit time. At the same time, the system also includes a calibration loop for the passive phase change energy storage section, i.e., module 4.0, which evaluates the current working state of the phase change energy storage section by analyzing the temperature response curve and generates an updated gain coefficient based on the evaluation results to update the current gain coefficient stored in database D2. This updated gain coefficient is also called by module 2.0 to adjust the strength of the quenching instruction, thereby forming a double closed-loop adaptive control system that can adapt to both fluid state changes and functional material performance fluctuations.

[0035] Example 4: Before putting a newly built fluid heating system for polymer extrusion into formal operation, it is necessary to conduct an offline parameter calibration and model construction for its control system, so that its feedforward control logic can match the physical conditions of this specific application scenario. The passive phase change energy storage section adopted by this system has an encapsulated phase change material with a melting point of 85°C, which is industrial-grade paraffin. The paraffin is infiltrated in a three-dimensionally connected open-cell copper framework to improve the response rate of the phase change material by using the high thermal conductivity of copper. Before calibration, the system circulates the fluid at the nominal flow rate without turning on any heating and refrigeration units, and continuously collects the readings of the reference temperature sensor and the perturbation temperature sensor for 300 seconds. The control unit calculates the standard deviation of the sensor signal noise during this period , and sets the gradient threshold required for triggering the thermal perturbation feedforward to three times the value of the standard deviation, i.e. 3 .

[0036] To establish the mapping relationship between the acoustic characteristics of the vortex tube exhaust noise and the fluid transit time correction parameters, the system is connected to a calibration loop with a precision adjustable speed pump and an external high-precision flowmeter. After starting the calibration program, the adjustable speed pump is controlled to drive the fluid at a series of discrete and increasing flow rate points, which cover the interval from 80% to 120% of the nominal flow rate. At each stable flow rate point, the control unit performs a preset quenching operation, and the acoustic sensor collects the vortex tube exhaust noise signal to calculate the corresponding spectral entropy value . At the same time, a small thermal pulse is injected downstream of the perturbation temperature sensor, and its arrival time at the quenching zone is recorded by an additional fast-response thermocouple, so as to obtain the actual transit time at this flow rate . The control unit compares this actual transit time with the initial transit time of the system at the nominal flow rate, so as to obtain the transit time correction parameter corresponding to this flow rate point . By traversing all the preset flow rate points, the system obtains a set of data pairs , , which are stored in the form of a lookup table in the non-volatile memory of the control unit, thereby constituting the core mapping relationship from acoustic characteristics to transit time correction.

[0037] After all the above calibration steps are completed, the adjustable speed pump and the external flow meter in the calibration loop are removed, and the system is reconnected to its standard working pump group; at this time, the system has completed the parameter setting and model construction for the current hardware configuration and fluid type, and its control unit can obtain the corresponding transit time correction parameter by querying the internally stored lookup table according to the real-time collected spectral entropy value in the subsequent online operation, without relying on any external measuring equipment; the entire calibration process converts the key parameters and internal models that may have been set empirically into an engineering data set that can be determined through a standardized experimental process, providing a basis for the system's operation in actual applications.

[0038] Example 5: When a set of the system of the present application has been continuously running for more than 2000 hours and needs to perform an online internal state self-check and parameter verification, the control unit can be placed in a preset maintenance mode; in this mode, to verify the rate threshold of the passive phase change energy storage section, the system first heats the temperature of the energy storage section to a state above its phase change point, causing the internal phase change material to completely melt, then injects a standardized cold gas flow pulse, and records the absolute value of the temperature recovery rate , then the system cools the energy storage section to a state below its phase change point, causing it to completely solidify, and repeats the above pulse injection and rate recording steps to obtain the absolute value of the temperature recovery rate in the solid state , the control unit then sets the rate threshold to the arithmetic mean of the two measured values, i.e. , and uses this calculated threshold for subsequent online evaluation of the working state of the phase change material.

[0039] Next, to verify the long-term effectiveness of the mapping relationship between the acoustic characteristics and the transit time correction parameter, an external and calibrated flow meter is temporarily connected in series in the fluid circuit; with the assistance of the flow meter, the fluid flow rate is adjusted to the nominal flow rate most commonly used in production, and under this stable working condition, a quenching operation is triggered by the control unit, and the spectral entropy value of the vortex tube exhaust noise at this moment is recorded The control unit compares the real-time measured spectral entropy value with the original spectral entropy value stored by the system at the initial calibration and corresponding to the same nominal flow rate , if the deviation between the two is less than a tolerance set based on the statistical dispersion of the initial calibration data, it proves that the original mapping relationship is still effective; if the deviation exceeds the tolerance, it indicates that the acoustic characteristics of the system may have drifted, at which time the control unit will generate a maintenance alert and record the event log, prompting the need for a complete offline re-calibration process; after the online verification procedure is completed, the external flow meter is removed, and the system returns to normal operation mode.

[0040] Example 6: Before deploying the system in a temperature control loop of a biopharmaceutical reactor with a new type of coolant, a site installation and control parameter tuning is required; first, to determine the physical distance between the reference temperature sensor and the disturbance temperature sensor , a series of standardized heat pulses are injected into the fluid on a test pipe section with multiple reserved sensor mounting ports, and the calculated temperature difference is recorded by the control unit at different mounting distances The signal-to-noise ratio and waveform characteristics of the signal are finally selected to maximize the signal-to-noise ratio and minimize the waveform spread of the signal The distance is selected as the fixed installation distance for the application; after determining the distance, the gain of the quench control command is calibrated, and the control unit injects a series of heat disturbances with known energy levels into the fluid, and for each heat disturbance level , the system tries different quenching times in an incremental manner , and records the temperature deviation of the downstream monitoring point after each quenching until a quenching time is found that minimizes the temperature deviation, and by traversing all heat disturbance levels, the system constructs an internal data table representing the functional relationship between temperature difference and quenching time .

[0041] After the above parameter calibration, the system performs a self-checking program of the actuator state to deal with the boundary condition that the vortex tube fails due to fluctuations in gas source pressure or its own failure; the control unit is configured to analyze the total energy of the signal from the acoustic sensor at the exhaust port of the micro vortex tube simultaneously when issuing any quenching control command; at the initial start of the system, a standard test is performed to record the reference acoustic energy value under normal working conditions; in subsequent operation, if the control unit fails to receive acoustic energy signals from the acoustic sensor that exceed a certain percentage of the reference value within a short time window after issuing the quenching command, it is determined that the actuator or its gas source has failed; once a failure is determined, the control unit will immediately suspend the heat disturbance feedforward quenching function to avoid false control output, and at the same time generate an alarm on the human-machine interaction interface that requires manual intervention, and switch the system to a backup operation mode that relies on the main heating unit for basic temperature maintenance; this series of procedures provides protection for the performance configuration and operational reliability of the system in specific application scenarios.

[0042] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application.

[0043] Finally, it should be noted that the above examples are merely intended to illustrate the technical solutions of the present application and not to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A precision temperature-controlled fluid heating system based on vortex tube cooling, characterized in that: The system includes a flow channel and a control unit arranged along the flow direction of the fluid; a reference temperature sensor arranged in the upstream section of the flow channel and a disturbance temperature sensor arranged downstream of the reference temperature sensor; a quenching zone arranged downstream of the disturbance temperature sensor, the quenching zone being provided with a micro vortex tube; and an acoustic sensor arranged at the exhaust port of the micro vortex tube. The control unit is connected to the reference temperature sensor, the disturbance temperature sensor, the micro vortex tube and the acoustic sensor. The system stores the gradient threshold and the initial transit time representing the flow of thermal disturbance from the disturbance temperature sensor position to the quenching zone position; The control unit is configured to: calculate a temperature difference between temperature readings of the reference temperature sensor and the disturbance temperature sensor; determining a transit time correction parameter based on acoustic characteristics of exhaust noise collected by an acoustic sensor; When the absolute value of the temperature difference exceeds the gradient threshold, the control unit determines a quenching control instruction based on the temperature difference, the initial transit time, and the transit time correction parameter, and outputs the quenching control instruction to the micro vortex tube.

2. A precision temperature-controlled fluid heating system based on vortex tube cooling according to claim 1, characterized in that: The system stores the mapping relationship between acoustic characteristics and transit time correction parameters; The control unit is configured to determine a transit time correction parameter based on acoustic characteristics of exhaust noise collected by the acoustic sensor, including: the control unit collects a sound pressure signal of the exhaust noise within a predetermined frequency band and calculates a spectral entropy value of the sound pressure signal as the acoustic characteristic; And the control unit determines a transit time correction parameter corresponding to the spectral entropy value based on the mapping relationship.

3. The precision temperature-controlled fluid heating system based on vortex tube cooling according to claim 1, characterized in that: A passive phase-change energy storage section is provided downstream of the quenching zone; a rate threshold is also stored in the system; and the control unit is further configured to: periodically control the micro-vortex tube to inject a cold airflow pulse of fixed duration into the phase-change energy storage section; and calculate the temperature recovery rate of the temperature response curve based on a temperature response curve collected by a disturbance temperature sensor after the cold airflow pulse injection; And when the absolute value of the temperature recovery rate is less than the rate threshold, that is, , the control unit increases the gain coefficient based on which it determines the quenching control instruction; wherein, is the absolute value of the temperature recovery rate, is the rate threshold.

4. The precise temperature-controlled fluid heating system based on vortex tube cooling according to claim 1, characterized in that: The quenching control instruction includes an opening instruction of the micro vortex tube and duration information representing the duration of the cold air flow ejected therefrom.

5. The precise temperature-controlled fluid heating system based on vortex tube cooling according to claim 4, characterized in that: When the control unit determines the duration information, the duration information is proportional to the absolute value of the temperature difference.

6. The precise temperature-controlled fluid heating system based on vortex tube cooling according to claim 1, characterized in that: The micro vortex tube is connected to a compressed air line that is in communication with an existing compressed air source at the location where the industrial equipment hosting the system is located.

7. The precise temperature-controlled fluid heating system based on vortex tube cooling according to claim 1, characterized in that: Both the reference temperature sensor and the disturbance temperature sensor are infrared temperature sensors.

8. The precise temperature-controlled fluid heating system based on vortex tube cooling according to claim 7, characterized in that: The system also includes an air guide pipe, one end of which is connected to the cold air outlet of the micro vortex tube, and the other end is opened in front of the lens of the infrared temperature sensor to form an air curtain to isolate water vapor from the external environment.

9. The precise temperature-controlled fluid heating system based on vortex tube cooling according to claim 8, characterized in that: The system also stores a frequency threshold; the control unit is further configured to: analyze the frequency of the interference pulse formed by the residual water vapor penetrating the air curtain in the signal of the infrared temperature sensor; and when the frequency of the interference pulse exceeds the frequency threshold, the control unit further increases the intensity of the cold air flow ejected by the micro vortex tube corresponding to the quenching control instruction when determining the quenching control instruction.

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