A water bath temperature control system and method for PMI polymerization reaction

Abstract

This invention discloses a water bath temperature control system and method for PMI polymerization reaction, including a polymerization water tank, a phase change energy storage module, multiple micro-nozzles, a liquid supply pipeline, a local temperature sensor, a background temperature maintenance system, and a control unit. The phase change energy storage module encapsulates a phase change material, stabilizing the overall water temperature of the water tank near the phase change point. Based on the real-time temperature deviation of each mold, the control unit independently controls the corresponding micro-nozzle to spray cold or hot water onto the mold surface using a PID algorithm, achieving precise local temperature correction. The method includes three steps: passive background temperature stabilization, active local temperature fine-tuning, and phase change material regeneration. This invention employs a combined passive buffering and active fine-tuning strategy, significantly improving temperature control accuracy, reducing energy consumption, and eliminating temperature differences between molds within a batch without relying on compression refrigeration. Simultaneously, the system is redundant, reliable, and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of polymer reaction temperature control technology, specifically to a water bath temperature control system and method for PMI polymerization reaction. Background Technology

[0002] The PMI foam polymerization reaction is carried out in a large water bath. The reaction cycle is long, with constant temperature in the early stage and temperature increase in the later stage. Moreover, the reaction is an exothermic process, and heat needs to be continuously removed in the middle and later stages.

[0003] Existing temperature control technologies suffer from the following problems: Air source heat pump systems transfer heat through compressors, but as an environmental heat or cold source, they can interfere with the surrounding temperature field, leading to unstable control, large temperature fluctuations, and high energy consumption. In refrigeration unit and electric heating combination schemes, cooling and heating often alternate, resulting in heat and cold cancellation, extremely high energy consumption, and environmental hazards posed by the refrigerant. Single-tank hot and cold water mixing temperature control directly injects hot and cold water into the water tank, easily creating localized areas of undercooling or overheating, uneven temperature distribution within the tank, significant differences in the reaction progress of the molds at different locations, and low control accuracy.

[0004] Furthermore, conventional PID feedback control struggles to handle the severe disturbances caused by the exothermic peak of the reaction, exhibiting hysteresis and overshoot issues. Existing systems generally cannot achieve high-precision temperature control without relying on compression refrigeration, nor can they independently adjust the temperature of each mold, resulting in poor product consistency within batches.

[0005] Therefore, there is an urgent need for a PMI polymerization water bath temperature control solution that features non-compression refrigeration, low energy consumption, high temperature control accuracy, and the ability to eliminate temperature differences between molds. Summary of the Invention

[0006] The purpose of this invention is to provide a water bath temperature control system and method for PMI polymerization reaction, so as to solve the problem that the existing technology cannot meet the high precision requirements in the later stage of PMI reaction.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A water bath temperature control system for PMI polymerization reaction includes: A polymerization tank is used to hold the water bath medium and multiple PMI resin molds; At least one phase change energy storage module is fixedly disposed inside or on the side wall of the polymerization tank. The phase change energy storage module is encapsulated with a phase change material, and the phase change temperature of the phase change material is... Target temperature of PMI polymerization reaction Satisfy | — |≤2 ℃; Multiple micro-nozzles, each micro-nozzle corresponding to a resin mold or a group of resin molds, wherein the spraying direction of the micro-nozzle points to the surface of the corresponding mold; Multiple liquid supply lines, including cold water lines and hot water lines, each line is connected to one or more micro nozzles, and each line is equipped with an independently controllable valve; Multiple local temperature sensors, each positioned near or inside a resin mold, are used to collect the local temperature of the mold in real time. ,in Here is the mold number, and t is the time. A background temperature maintenance system is used to maintain the overall water temperature within the polymerization tank. Maintain at Within the range, of which The background temperature maintenance system does not include a compression refrigeration device; A control unit that receives data from all local temperature sensors. And execute the following control algorithm: For each mold Calculate the temperature deviation: Set a dead zone threshold δ>0, when | When |≤δ, the control unit does not trigger the spraying action of the corresponding micro-nozzle; when Calculate the required cooling jet flow rate. : in , , The proportional, integral, and derivative coefficients for the cooling mode; the control unit opens the valve of the corresponding cold water pipeline, causing the micro-nozzle to operate at a flow rate of... Spray cold water onto the mold surface; when Calculate the required heating jet flow rate. : in , , The proportional, integral, and derivative coefficients for the heating mode; the control unit opens the valve of the corresponding hot water pipe, causing the micro-nozzle to operate at a flow rate... Spray hot water onto the mold surface; The phase change energy storage module is used to absorb or release heat fluctuations caused by the exothermic PMI reaction or environmental changes, in order to maintain... Within the specified range, the micro-spray array is used to independently correct local temperature deviations in each mold.

[0008] In a further embodiment, the background temperature maintenance system includes a natural pool, a cold pool, and a hot pool, wherein the temperature of the cold pool is... The temperature of the hot pool is The temperature of the natural pool is ,and The background temperature maintenance system adjusts the temperature by replenishing water from the cold or hot pool to the polymerization tank and discharging an equal amount of water. The flow rate of the supplemental water is controlled by a proportional regulating valve and does not rely on compression refrigeration or air source heat pump.

[0009] In a further embodiment, multiple phase change energy storage modules are arranged in an array along the sidewall or bottom of the aggregation tank. Different phase change energy storage modules encapsulate materials with different phase change temperatures, which are selected from... , , And satisfy Adjacent differences do not exceed Multiple phase change energy storage modules with different phase change temperatures are employed and distributed vertically along a temperature gradient (lower layer at the bottom, higher layer at the top) to match the naturally formed temperature stratification within the water tank, eliminating the vertical temperature gradient and making the background temperature more uniform throughout the tank. This staged absorption / release of heat improves the utilization efficiency of the phase change material and further reduces background temperature fluctuations.

[0010] A method for controlling the water bath temperature of a PMI polymerization reaction includes the following steps: Step S1: Passive stabilization of background temperature Utilizing the phase change material within the phase change energy storage module, when the overall water temperature of the polymerization tank... Higher than When the phase change material melts and absorbs heat; when Below At that time, the phase change material releases heat upon solidification, thereby... Automatic clamping position ± Within the range, where Δ It is determined by the latent heat, mass, and heat load of the water tank of the phase change material; Step S2: Active local temperature fine-tuning for each mold Real-time acquisition of its local temperature Perform the following sub-steps: Step S2.1: Calculate the deviation ; Step S2.2: If The cooling jet flow rate is then calculated using the following PID algorithm: in: : No. The cold water jet flow rate of the mold at time t, in units of ; Temperature deviation, in °C; Cooling mode proportional gain, in units of ; Integral gain in cooling mode, in units of ; Differential gain in cooling mode, in units of ; τ: Integral variable, in seconds; The control unit opens the corresponding cold water pipeline valve, allowing the micro-nozzle to operate at a flow rate of... Spray cold water onto the mold surface; Step S2.3: If The heating jet flow rate is then calculated using the following PID algorithm: in: : No. The hot water jet flow rate of a mold at time t, in m3 / s; : The absolute value of the temperature deviation, in °C; Heating mode proportional gain, in units of ; Integral gain in heating mode, in units of ; Differential gain of heating mode, in units of ; The control unit opens the corresponding hot water pipe valve, allowing the micro-sprinkler to operate at a flow rate of... Spray hot water onto the mold surface; Step S2.4: If | If |≤δ, the control unit will not trigger the injection action; Step S3: Regeneration of Phase Change Material During the intermittent period of the PMI polymerization reaction or after the reaction is completed, the background temperature maintenance system supplies the phase change energy storage module with an air temperature lower than [the required temperature]. The circulating water causes the molten phase change material to re-solidify, restoring its latent heat storage capacity.

[0011] In a further embodiment, in step S2, the micro-nozzle sprays using a pulse width modulation mode, i.e., the duty cycle of valve opening within each control cycle. With calculation flow or It is proportional, and the duration of a single jet pulse does not exceed 50ms.

[0012] A further embodiment includes the proportional, integral, and differential gain of the cooling mode. , , And heating mode proportional, integral, and derivative gain , , The system can be tuned offline using historical data from previous batches, or adjusted online by the control unit using a self-tuning algorithm during operation.

[0013] In a further embodiment, the local temperature sensor collects... After processing by a low-pass filter, the filter cutoff frequency is... satisfy To eliminate instantaneous noise caused by the injection process, the local temperature sensor signal is low-pass filtered with a cutoff frequency not higher than 0.5Hz.

[0014] In a further embodiment, in step S1 satisfy And determined by the mass of the phase change material Latent heat L and maximum heat release power of the polymerization tank The following design formula is used to determine: in The time required to absorb the exothermic peak is expressed in seconds.

[0015] In a further embodiment, the regeneration process of the background temperature maintenance system in step S3 involves a circulating water flow rate... Based on the real-time solid fraction of the phase change material Adjustments are needed: in Obtained through thermal balance calculations or direct measurements. This is the preset maximum regeneration flow rate.

[0016] In a further embodiment, the method also includes a feedforward compensation step: predicting the exothermic rate based on historical exothermic curves before the peak of the polymerization reaction. Lowering the background temperature setting or increasing the solid proportion of the phase change material in advance can help reserve more heat absorption capacity.

[0017] The present invention has the following beneficial effects: This invention utilizes the synergistic effect of passive clamping by a phase change energy storage module and active fine-tuning by a micro-spray array to stabilize the background temperature of the water tank near the phase change point. Simultaneously, local deviations in each mold are rapidly corrected by independent PID control. Compared to existing solutions that suffer from temperature fluctuations due to alternating heating and cooling, uneven mixing, or feedback lag, this invention improves temperature control accuracy by more than an order of magnitude, meeting the stringent temperature requirements of the later stages of PMI polymerization.

[0018] This invention's phase change energy storage module absorbs or releases exothermic reactions without requiring external energy; the micro-spray array requires only a small amount of water for localized correction; and the background temperature maintenance system does not rely on compression refrigeration or air-source heat pumps, fully utilizing factory waste heat and natural cold sources. This invention avoids energy waste caused by heat and cold offsetting, and its overall operating energy consumption is significantly lower than existing compressor-dependent technologies.

[0019] This invention features independent temperature control for each mold, eliminating temperature differences caused by uneven flow fields within the water tank and variations in individual heat release. This ensures that all molds undergo a highly consistent temperature process, significantly improving product uniformity. Furthermore, the phase-change energy storage and micro-spray array are redundant, allowing the other system to maintain a safe temperature for a short period in the event of a failure in either subsystem. With no easily damaged compression components, it also boasts high long-term operational stability. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the polymerization unit of the present invention; Figure 2 This is a schematic diagram of the micro-spray array principle of the present invention; Figure 3 This is a schematic diagram illustrating the relative position of the micro-nozzle and the mold in this invention. Figure 4 This is a schematic diagram of the regeneration cycle of the phase change material of the present invention. Detailed Implementation

[0021] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0022] Example 1 Please refer to Figures 1-4 As shown, a water bath temperature control system for PMI polymerization reaction includes: A polymerization tank is used to hold the water bath medium and multiple PMI resin molds; At least one phase change energy storage module is fixedly disposed inside or on the side wall of the polymerization tank. The phase change energy storage module is encapsulated with a phase change material, and the phase change temperature of the phase change material is... Target temperature of PMI polymerization reaction Satisfy | — |≤2 ℃; Multiple micro-nozzles, each micro-nozzle corresponding to a resin mold or a group of resin molds, wherein the spraying direction of the micro-nozzle points to the surface of the corresponding mold; Multiple liquid supply lines, including cold water lines and hot water lines, each line is connected to one or more micro nozzles, and each line is equipped with an independently controllable valve; Multiple local temperature sensors, each positioned near or inside a resin mold, are used to collect the local temperature of the mold in real time. ,in The mold number is t, and time is t. A background temperature maintenance system is used to maintain the overall water temperature within the polymerization tank. Maintain at Within the range, of which The background temperature maintenance system does not include a compression refrigeration device; A control unit that receives data from all local temperature sensors. And execute the following control algorithm: For each mold Calculate the temperature deviation: Set a dead zone threshold δ>0, when | When |≤δ, the control unit does not trigger the spraying action of the corresponding micro-nozzle; when Calculate the required cooling jet flow rate. : in , , The proportional, integral, and derivative coefficients for the cooling mode; the control unit opens the valve of the corresponding cold water pipeline, causing the micro-nozzle to operate at a flow rate of... Spray cold water onto the mold surface; when Calculate the required heating jet flow rate. : in , , The proportional, integral, and derivative coefficients for the heating mode; the control unit opens the valve of the corresponding hot water pipe, causing the micro-nozzle to operate at a flow rate... Spray hot water onto the mold surface; The phase change energy storage module is used to absorb or release heat fluctuations caused by the exothermic PMI reaction or environmental changes, in order to maintain... Within the specified range, the micro-spray array is used to independently correct local temperature deviations for each mold. The phase change energy storage module provides passive temperature clamping, the micro-spray array provides active local correction, and the PID algorithm achieves precise closed-loop control. The background temperature maintenance system does not include compression refrigeration equipment, thus eliminating high-energy-consuming solutions. The dead zone threshold δ avoids frequent valve operation. Through active and passive coordination, high-precision temperature control at both the overall and local levels is achieved without relying on a compressor. Independent PID control for each mold eliminates temperature differences between molds. The overall structure is compact, the control logic is clear, and it possesses extremely high energy efficiency and temperature control stability.

[0023] The background temperature maintenance system includes a natural pool, a cold pool, and a hot pool, wherein the temperature of the cold pool is... The temperature of the hot pool is The temperature of the natural pool is ,and The background temperature maintenance system adjusts the temperature by replenishing water from the cold or hot pool to the polymerization tank and discharging an equal amount of water. The flow rate of the supplementary water is controlled by a proportional regulating valve and does not rely on compression refrigeration or air-source heat pumps. It provides an optimal three-pool (natural pool, cold pool, and hot pool) implementation for the background temperature maintenance system, utilizing natural cold sources and waste heat sources, with the temperature satisfying cold pool < phase change point < hot pool. This ensures both cooling and heating capabilities, relying entirely on natural thermal gradients and waste heat recovery, eliminating active energy consumption for cooling or heating, further reducing operating costs. The three-pool structure is simple, reliable, and easy to implement in factory environments.

[0024] The phase change energy storage modules are multiple and arranged in an array along the sidewall or bottom of the aggregation tank. Different phase change energy storage modules are encapsulated with materials with different phase change temperatures, which are selected from... , , And satisfy Adjacent differences do not exceed Multiple phase change energy storage modules with different phase change temperatures are employed and distributed vertically along a temperature gradient (lower layer at the bottom, higher layer at the top) to match the naturally formed temperature stratification within the water tank, eliminating the vertical temperature gradient and making the background temperature more uniform throughout the tank. This staged absorption / release of heat improves the utilization efficiency of the phase change material and further reduces background temperature fluctuations.

[0025] This invention also discloses a water bath temperature control method for PMI polymerization reaction, comprising the following steps: Step S1: Passive stabilization of background temperature Utilizing the phase change material within the phase change energy storage module, when the overall water temperature of the polymerization tank... Higher than When the phase change material melts and absorbs heat; when Below At that time, the phase change material releases heat upon solidification, thereby... Automatic clamping position ± Within the range, where Δ It is determined by the latent heat, mass, and heat load of the water tank of the phase change material; Step S2: Active fine-tuning of local temperature For each mold Real-time acquisition of its local temperature Perform the following sub-steps: Step S2.1: Calculate the deviation ; Step S2.2: If The cooling jet flow rate is then calculated using the following PID algorithm: in: : No. The cold water jet flow rate of the mold at time t, in units of ; Temperature deviation, in °C; Cooling mode proportional gain, in units of ; Integral gain in cooling mode, in units of ; Differential gain in cooling mode, in units of ; τ: Integral variable, in seconds; The control unit opens the corresponding cold water pipeline valve, allowing the micro-nozzle to operate at a flow rate of... Spray cold water onto the mold surface; Step S2.3: If The heating jet flow rate is then calculated using the following PID algorithm: in: : No. The hot water jet flow rate of a mold at time t, in m3 / s; : The absolute value of the temperature deviation, in °C; Heating mode proportional gain, in units of ; Integral gain in heating mode, in units of ; Differential gain of heating mode, in units of The control unit opens the corresponding hot water pipe valve, allowing the micro-sprinkler to operate at a flow rate of... Spray hot water onto the mold surface; Step S2.4: If | If |≤δ, the control unit will not trigger the injection action; Step S3: Regeneration of Phase Change Material During the intermittent period of the PMI polymerization reaction or after the reaction is completed, the background temperature maintenance system supplies the phase change energy storage module with an air temperature lower than [the required temperature]. The circulating water re-solidifies the molten phase change material, restoring its latent heat storage capacity. A three-step method is fully defined: passive stabilization, active fine-tuning, and regeneration. Active fine-tuning employs a PID algorithm with dead zone, and the calculation formulas and letter meanings for both cooling and heating modes are clearly given. The PID algorithm is mature and reliable, and the dead zone setting avoids frequent actuator operations. Separating cooling and heating modes makes control more precise. The regeneration step ensures the system's reusability.

[0026] In step S2, the micro-nozzle sprays using a pulse width modulation mode, which is the duty cycle of valve opening within each control cycle. With calculation flow or The duty cycle is proportional to the calculated flow rate, and the duration of a single injection pulse does not exceed 50ms. The micro-nozzle control employs pulse width modulation (PWM) mode, with the duty cycle proportional to the calculated flow rate. The PWM mode avoids the valve nonlinearity problem at low flow rates, improving flow control linearity and repeatability. Short pulses allow for rapid response, reducing the disturbance to the overall water temperature of the tank from a single injection.

[0027] The cooling mode proportional, integral, and differential gain , , And heating mode proportional, integral, and derivative gain , , By offline tuning using historical data from previous batches, or online adjustment by the control unit using a self-tuning algorithm during operation, it is clear that PID gain can be obtained through offline tuning (based on historical data) or online self-tuning. Two implementation methods are presented to adapt to changes in exothermic characteristics under different batches, raw materials, and environmental conditions. Self-tuning can reduce the workload of manual debugging and improve the system's intelligence and robustness.

[0028] The local temperature sensor collected the data. After processing by a low-pass filter, the filter cutoff frequency is... satisfy To eliminate the instantaneous noise caused by the injection process, the local temperature sensor signal is low-pass filtered with a cutoff frequency not higher than 0.5Hz to eliminate the instantaneous noise caused by the injection action. After filtering out high-frequency noise, the PID controller will not malfunction due to false spikes, resulting in smoother control output, extended valve life, and unaffected temperature control accuracy.

[0029] In step S1 satisfy And determined by the mass of the phase change material Latent heat L and maximum heat release power of the polymerization tank The following design formula is used to determine: in The design criteria for phase change energy storage modules are given, expressed in seconds, for the required time to absorb the exothermic peak. Specifically, the total latent heat capacity must be greater than the product of the maximum exothermic power and the required exothermic absorption time. This is quantified using a formula to ensure that the phase change material can completely absorb the impact of the exothermic peak and avoid exceeding the background temperature limit. The theoretical basis for engineering design is provided, enabling the system to be scaled up and replicated.

[0030] The regeneration process of the background temperature maintenance system in step S3, the flow rate of its circulating water Based on the real-time solid fraction of the phase change material Adjustments are needed: in Obtained through thermal balance calculations or direct measurements. To preset the maximum regeneration flow rate, the regeneration circulating water flow rate is linearly adjusted during the regeneration process based on the real-time solid fraction of the phase change material. A lower flow rate is applied when the solid fraction is high, and a higher flow rate is applied when the solid fraction is low. This avoids energy waste and excessive cooling caused by a constant high flow rate, ensuring complete solidification of the phase change material while saving energy. This achieves on-demand regeneration and extends pump life.

[0031] The method also includes a feedforward compensation step: predicting the exothermic rate based on historical exothermic curves before the peak of the polymerization reaction. To mitigate the heat loss, the background temperature setpoint can be lowered in advance or the solid-state ratio of the phase change material can be increased to reserve more heat absorption capacity. A feedforward compensation step can also be added: before the peak of heat release, based on historical heat release curves, the background temperature can be lowered or the solid-state ratio of the phase change material can be increased. This combination of feedforward and feedback further suppresses the temperature surge caused by the heat release peak. Historical data can be used to predict future disturbances, transforming passive response into proactive prevention and controlling temperature fluctuations within a smaller range.

[0032] Specific application scenarios: This system was implemented in a PMI resin plant with an annual output of 800 tons.

[0033] System Construction: Aggregate water tank: 12m long, 3m wide, and 1.2m deep, made of stainless steel with external insulation.

[0034] Phase change energy storage module: Utilizes 50 flat-panel modules, each measuring 1m × 0.5m × 0.05m, internally encapsulated with paraffin-based phase change material, phase change temperature... =30℃, latent heat L=200 kJ / kgL, total mass =5000kg. The module is attached to the side wall and bottom of the water tank.

[0035] Micro-nozzle array: 28 micro-nozzles, each corresponding to one resin mold. Nozzle orifice diameter: 0.5mm; operating pressure: 0.2MPa. Cold water piping connected to the cold bath (temperature...). =17℃), hot water pipes are connected to the hot pool (temperature) =60℃).

[0036] Local temperature sensor: PT100 platinum resistance thermometer, installed on the inner wall of each mold.

[0037] Background temperature maintenance system: Composed of a natural pool, a cold pool, and a hot pool, it controls the injection of hot and cold water through proportional valves to maintain the overall water temperature of the tank. Maintain at 30±0.1℃. This system has no compression refrigeration equipment.

[0038] Control unit: Siemens S7-1500 PLC, sampling period 0.1s, PID calculation period 0.5s.

[0039] Control parameters: Target temperature =30℃ Dead zone threshold δ = 0.02℃ Cooling mode PID coefficients: =0.001 , = , =0.00005 ; Heating mode PID coefficients: =0.0008 , =0.00008 , =0.00004 ; Operation process: Initial stage: 30°C water (obtained by mixing natural pool and hot pool) is injected into the water tank, and the phase change material is solid.

[0040] Mid-reaction phase (peak exothermic reaction): The exothermic reaction causes the water temperature to rise, and the phase change material begins to melt and absorb heat. The temperature was kept below 30.1℃. Simultaneously, the control unit detected that the temperature of some mold sections exceeded 30.02℃. Based on the PID calculation, a small amount of cold water (typical flow rate 0.002~0.01 L / s) was sprayed onto the mold surface by micro-nozzles, causing the mold temperature to drop rapidly. The measured mold temperature fluctuation was ±0.018℃.

[0041] Later stage of the reaction (heating stage): The temperature is programmed to rise to 47°C. At this point, the phase change material has completely melted. The background temperature maintenance system gradually increases the water temperature, and the micro-nozzle switches to hot water mode to assist in heating.

[0042] Regeneration stage: After the batch is completed, the background temperature maintenance system draws water from the natural pool (water temperature of about 20°C) and circulates it through the phase change energy storage module to allow the paraffin to solidify again for later use.

[0043] Energy consumption and accuracy test results: Compared with traditional air source heat pump solutions: The total power consumption of this embodiment is 120kWh per batch (mainly for water pumps and PLCs), while the traditional solution is 1500kWh, resulting in energy savings of 92%.

[0044] Temperature fluctuation: The background temperature of the water tank fluctuates by ±0.07℃, and the surface temperature of each mold fluctuates by ±0.015℃.

[0045] Product consistency: The standard deviation of PMI foam density for 28 molds was 0.8%, compared to 3.5% for the traditional method.

[0046] Example 2 (Graded Phase Change Materials) Based on Example 1, the phase change energy storage module is divided into three layers, each encapsulating a phase change material with a phase change temperature of 28°C, 30°C, and 32°C, respectively. When the temperature at the bottom of the water tank is lower, the 28°C module absorbs heat first; the middle part is at 30°C; and the upper part is at 32°C. This arrangement further reduces the vertical temperature gradient, reducing background temperature fluctuations to ±0.05°C.

[0047] Example 3 (Pulse Width Modulation Injection) In the micro-spray control of Example 1, PWM mode is adopted: within each control cycle (0.5s), the duty cycle of valve opening is... satisfy: in =0.02L / s represents the fully open valve flow rate. The minimum opening time for a single pulse is 5ms. This mode avoids the non-linear region of the valve at low flow rates, thus improving control accuracy.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water bath temperature control system for PMI polymerization reaction, characterized in that, include: A polymerization tank is used to hold the water bath medium and multiple PMI resin molds; At least one phase change energy storage module is fixedly disposed inside or on the side wall of the polymerization tank. The phase change energy storage module is encapsulated with a phase change material, and the phase change temperature of the phase change material is... Target temperature of PMI polymerization reaction Satisfy | — |≤2 ℃; Multiple micro-nozzles, each micro-nozzle corresponding to a resin mold or a group of resin molds, wherein the spraying direction of the micro-nozzle points to the surface of the corresponding mold; Multiple liquid supply lines, including cold water lines and hot water lines, each line is connected to one or more micro nozzles, and each line is equipped with an independently controllable valve; Multiple local temperature sensors, each positioned near or inside a resin mold, are used to collect the local temperature of the mold in real time. ,in Here is the mold number, and t is the time. A background temperature maintenance system is used to maintain the overall water temperature within the polymerization tank. Maintain at Within the range, The background temperature maintenance system does not include a compression refrigeration device; A control unit that receives data from all local temperature sensors. and execute the corresponding control algorithm: The control unit opens the valve of the corresponding hot water pipe, allowing the micro-sprinkler to operate at a flow rate of... Spray hot water onto the mold surface; The phase change energy storage module is used to absorb or release heat fluctuations caused by the exothermic PMI reaction or environmental changes, in order to maintain... Within the specified range, the micro-spray array is used to independently correct local temperature deviations in each mold.

2. The water bath temperature control system for PMI polymerization reaction according to claim 1, characterized in that, The control algorithm in the control unit is as follows: For each mold Calculate the temperature deviation: Set the dead zone threshold δ>0, when | When |≤δ, the control unit does not trigger the spraying action of the corresponding micro-nozzle; when Calculate the required cooling jet flow rate. : in , , The proportional, integral, and derivative coefficients for the cooling mode; the control unit opens the valve of the corresponding cold water pipeline, causing the micro-nozzle to operate at a flow rate of... Spray cold water onto the mold surface; when Calculate the required heating jet flow rate. : in , , These are the proportional, integral, and derivative coefficients for the heating mode.

3. The water bath temperature control system for the PMI polymerization reaction according to claim 1, characterized in that, The background temperature maintenance system includes a natural pool, a cold pool, and a hot pool, wherein the temperature of the cold pool is... The temperature of the hot pool is The temperature of the natural pool is ,and The background temperature maintenance system adjusts the temperature by replenishing water from the cold or hot pool to the polymerization tank and discharging an equal amount of water. The flow rate of the supplemental water is controlled by a proportional regulating valve and does not rely on compression refrigeration or air source heat pump.

4. The water bath temperature control system for PMI polymerization reaction according to claim 1, characterized in that, The phase change energy storage modules are multiple and arranged in an array along the sidewall or bottom of the aggregation tank. Different phase change energy storage modules are encapsulated with materials with different phase change temperatures, which are selected from... , , And satisfy Adjacent differences do not exceed .

5. A method for controlling the water bath temperature of a PMI polymerization reaction applied to the system described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step S1: Passive stabilization of background temperature Utilizing the phase change material within the phase change energy storage module, when the overall water temperature of the polymerization tank... Higher than When the phase change material melts and absorbs heat; when Below At that time, the phase change material releases heat upon solidification, thereby... Automatic clamping position ± Within the range, where Δ It is determined by the latent heat, mass, and heat load of the water tank of the phase change material; Step S2: Active local temperature fine-tuning for each mold Real-time acquisition of its local temperature Perform the following sub-steps: Step S2.1: Calculate the deviation ; Step S2.2: If The cooling jet flow rate is then calculated using the following PID algorithm: in: : No. The cold water jet flow rate of the mold at time t, in units of ; Temperature deviation, in °C; Cooling mode proportional gain, in units of ; Integral gain in cooling mode, in units of ; Differential gain in cooling mode, in units of ; τ: Integral variable, in seconds; The control unit opens the corresponding cold water pipeline valve, allowing the micro-nozzle to operate at a flow rate of... Spray cold water onto the mold surface; Step S2.3: If The heating jet flow rate is then calculated using the following PID algorithm: in: : No. The hot water jet flow rate of a mold at time t, in m3 / s; : The absolute value of the temperature deviation, in °C; Heating mode proportional gain, in units of ; Integral gain in heating mode, in units of ; Differential gain of heating mode, in units of ; The control unit opens the corresponding hot water pipe valve, allowing the micro-sprinkler to operate at a flow rate of... Spray hot water onto the mold surface; Step S2.4: If | If |≤δ, the control unit will not trigger the injection action; Step S3: Phase change material regeneration. During the PMI polymerization reaction interval or after the reaction is completed, the background temperature maintenance system supplies the phase change energy storage module with an energy source at a temperature lower than [missing information]. The circulating water causes the molten phase change material to re-solidify, restoring its latent heat storage capacity.

6. The method according to claim 5, characterized in that, In step S2, the micro-nozzle sprays using a pulse width modulation mode, which is the duty cycle of valve opening within each control cycle. With calculation flow or It is proportional, and the duration of a single jet pulse does not exceed 50ms.

7. The method according to claim 5, characterized in that, The local temperature sensor collected the data. After processing by a low-pass filter, the filter cutoff frequency is... satisfy This is to eliminate the instantaneous noise caused by the injection process.

8. The method for PMI polymerization reaction according to claim 5, characterized in that, In step S1 satisfy And determined by the mass of the phase change material Latent heat L and maximum heat release power of the polymerization tank The following design formula is used to determine: in The time required to absorb the exothermic peak is expressed in seconds.

9. The method according to claim 5, characterized in that, The regeneration process of the background temperature maintenance system in step S3, the flow rate of its circulating water Based on the real-time solid fraction of the phase change material Adjustments are needed: in Obtained through thermal balance calculations or direct measurements. This is the preset maximum regeneration flow rate.

10. The method according to claim 5, characterized in that, The method also includes a feedforward compensation step: predicting the exothermic rate based on historical exothermic curves before the peak of the polymerization reaction. Lowering the background temperature setting or increasing the solid proportion of the phase change material in advance can help reserve more heat absorption capacity.

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