A control method of a three-dimensional calorimeter in a wide temperature range based on mechanical refrigeration and temperature difference power generation sheet

Abstract

The application discloses a wide-temperature-range three-dimensional calorimeter control method based on mechanical refrigeration and temperature difference power generation sheets, which is applied to a calorimeter loaded with a mechanical refrigeration system and a three-dimensional temperature difference power generation sheet sensing unit, and the method comprises the following steps: setting a target detection temperature and a temperature control precision threshold; collecting the core area temperature in real time through a uniform heating block center embedded temperature sensor; adopting a closed-loop control algorithm to cooperatively adjust heating power and refrigeration power; synchronously regulating the rotating speed of an adjustable speed fan to accelerate the uniformity of the cavity temperature; after the temperature is stabilized, synchronously collecting thermoelectric signals through three-dimensional distributed temperature difference power generation sheets; performing fusion calculation on the three-dimensional direction signals, and outputting calorimeter parameters in combination with pre-calibration parameters and full-temperature-range compensation. The application can realize accurate temperature control in a wide temperature range of-100 DEG C to 300 DEG C, significantly shortens the temperature balance time, improves the detection precision and sensitivity through three-dimensional signal fusion, and guarantees the stability and reliability of the operation in the full temperature range.

Description

Technical Field

[0001] This invention relates to a control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator. Background Technology

[0002] Calvet calorimeters, with their three-dimensional, all-around detection structure, can comprehensively monitor the thermal effects of the measured object, occupying an important position in the field of precision thermal analysis. However, existing Calvet three-dimensional calorimeters still have many technical shortcomings in practical applications, limiting their detection performance and applicability: Narrow temperature range coverage and high cost of low temperature testing: Most equipment relies solely on electric heating to achieve temperature rise, without active cooling function, and the working temperature range is limited to above room temperature; some equipment with cooling function uses liquid nitrogen filling cooling, which has problems such as short cooling duration, need for frequent material replenishment, cumbersome operation, and high operating cost, and the minimum stable working temperature is usually not lower than -40℃, and the temperature control accuracy in the low temperature range is significantly reduced.

[0003] Poor temperature uniformity and large detection error: Existing heat distribution blocks are mostly made of ordinary aluminum alloy or nickel-based materials, which have insufficient thermal conductivity and the surface temperature gradient usually exceeds ±3℃; the insulation layer is mostly made of glass wool or polyurethane foam, which has high thermal conductivity and limited insulation effect, and heat leakage channels are easily formed at the component connection. Ultimately, the calorimetric detection error is generally above ±3%, which cannot meet the requirements of high-precision detection.

[0004] Temperature control response is lagging and temperature zone switching efficiency is low: the heating and cooling systems have poor coordination and lack a precise matching mechanism. Heat diffusion inside the cavity relies on natural convection, and the temperature equilibrium time usually exceeds 30 minutes. At the same time, temperature sensors are mostly installed on the surface of the heat exchange block, which cannot accurately reflect the temperature of the sample area. The signal feedback delay is large, which further reduces the temperature control accuracy and response speed.

[0005] Limitations of calorimetric sensors: Traditional thermocouple sensors have insufficient sensitivity and weak response to small thermal field fluctuations; they mostly adopt an integrated packaging structure, which is inconvenient to assemble and maintain, and partial damage requires replacement of the whole unit; some three-dimensional sensors are spliced ​​from unidirectional units, which have detection blind spots and signal interference, and cannot fully utilize the three-dimensional detection advantages of the Calvet calorimeter.

[0006] In summary, existing technologies have not achieved deep integration between the mechanical refrigeration system and the calorimeter structure, nor have they fully utilized the efficient thermoelectric conversion characteristics of the thermoelectric generator. This results in the inability to achieve wide-range temperature control and high-sensitivity detection in tandem, limiting the application of the Calvet 3D calorimeter in high-precision, wide-range detection scenarios. Summary of the Invention

[0007] The main objective of this invention is to provide a control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator, aiming to solve the aforementioned technical problems.

[0008] To achieve the above objectives, this invention proposes a wide-temperature-range three-dimensional calorimeter control method based on mechanical refrigeration and a thermoelectric generator. This method is applied to a three-dimensional calorimeter, which includes a base, a heating chamber, a heat equalization block, a calorimetric sensing component, a mechanical refrigeration component, a temperature monitoring unit, and an external control module. The heating chamber is vertically fixed to the base, the heat equalization block is coaxially housed within the internal cavity of the heating chamber, the calorimetric sensing component is sealed at the top opening of the heating chamber, and the mechanical refrigeration component is located outside the heating chamber. The wide-temperature-range three-dimensional calorimeter control method based on mechanical refrigeration and a thermoelectric generator includes: S1. Set the target detection temperature and temperature control accuracy threshold through an external control module; S2. The actual temperature of the detection area of ​​the heat-uniform block is collected in real time by a temperature sensor embedded in the geometric center of the heat-uniform block, and the temperature signal is transmitted to the external control module. S3. The external control module compares the difference between the actual temperature and the target temperature, and uses a closed-loop control algorithm to dynamically adjust the heating power of the heating barrel and the cooling power of the spiral circulation cooling pipe to achieve the adjustment of the cavity temperature. S4. During the temperature control process, the external control module synchronously adjusts the speed of the adjustable fan, driving the airflow inside the cavity to circulate along the heat equalization block, accelerating heat diffusion and temperature uniformity. S5. After the cavity temperature stabilizes, the sample to be tested is placed on the surface of the uniform heating block. Multiple sets of thermoelectric generators distributed in three-dimensional space synchronously collect the temperature difference voltage signal generated by the thermal effect of the sample and transmit it to the external control module. S6. The external control module performs fusion calculations on the three-dimensional temperature difference and voltage signals, combines them with pre-calibrated parameters to obtain the calorimetric parameters of the sample under test, and outputs and stores them.

[0009] In one embodiment, the closed-loop control algorithm in step S3 specifically includes: When the actual temperature is lower than the target temperature, the output PWM pulse width modulation signal increases the heating power and synchronously matches the fan speed to accelerate heat dissipation. If the target temperature is lower than the room temperature, the refrigeration unit is started first for pre-cooling. After the temperature approaches the target temperature, the mode of fine-tuning the heating power is switched. When the actual temperature is higher than the target temperature, the refrigeration unit is started to drive the refrigerant to evaporate and absorb heat in the spiral circulation refrigeration pipe to cool down. At the same time, the fan speed is increased to accelerate the diffusion of cold energy. If the target temperature is higher than the room temperature and the temperature difference is ≤5℃, the temperature is adjusted back by reducing the heating power and combining it with fan heat dissipation. Once the actual temperature reaches the target temperature range, the current heating, cooling, and fan parameters are maintained, and minor power adjustments are made based on temperature feedback to keep the temperature stable.

[0010] In one embodiment, in step S2, the temperature sensor is embedded to a depth of 40 mm in the center of the heat-equalizing block, and thermal grease is filled between the sensor and the mounting hole wall to eliminate gaps.

[0011] In one embodiment, in step S5, multiple sets of thermoelectric generators are arranged along the x, y, and z three-dimensional coordinate axes, and each set of thermoelectric generators is kept in thermally conductive contact with the surface of the heat-equalizing block by an elastic pre-compression member; the thermoelectric generators convert the temperature difference at both ends into a voltage signal, and the signal is transmitted to the external control module via a shielded wire.

[0012] In one embodiment, step S6, the calorimetric data processing specifically includes: The original voltage signal of each thermoelectric generator is amplified and filtered according to the formula. Obtain the temperature difference value in the corresponding direction. ; in, denoted as Seebeck's coefficient for the thermoelectric generator, and N is the number of thermocouple pairs in the thermoelectric generator.

[0013] In one embodiment, step S6, the calorimetric data processing specifically further includes; The temperature difference values ​​in three dimensions are weighted and fused to eliminate detection bias in a single direction, resulting in a comprehensive temperature difference. ; According to the formula Calculate the calorific value Q of the sample being tested; Where k is the combined thermal conductivity of the heat exchanger and the sensing module, S is the effective contact area between the sample and the heat exchanger, and t is the calorimetric detection time. The predicted system heat loss value; The overall thermal conductivity k, effective contact area S, and system heat loss are mentioned. All were obtained through pre-calibration using standard samples, and the system heat loss was... The results were determined using a blank experiment without samples, within the temperature range of -80℃ to 300℃. .

[0014] In one embodiment, step S6 further includes a full-temperature-range temperature compensation step: The external control module uses the temperature compensation coefficient of the corresponding temperature zone to correct the output signal of the thermoelectric generator based on the current operating temperature zone.

[0015] In one embodiment, prior to step S1, the wide-temperature-range three-dimensional calorimeter control method based on mechanical refrigeration and thermoelectric generators further includes a pre-run calibration step: After starting the equipment, set the reference temperature and run for a preset time to complete the temperature drift calibration. At the same time, measure the system heat loss value under the current environmental conditions through a blank experiment and update it to the control parameter library.

[0016] In the technical solution of this invention, a closed-loop control logic of heating-cooling coordination is adopted. Combined with a mechanical refrigeration system, it can achieve wide temperature range control from -100℃ to 300℃, breaking through the temperature range limitation of traditional calorimeters. Different temperature control strategies are adopted for different temperature ranges: pre-cooling + heating fine-tuning in the low temperature range, and power reduction + fan cooling in the small temperature difference range, to ensure the temperature control accuracy and stability of the entire temperature range. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the control method for a wide-temperature-range, high-sensitivity three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generators, according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a three-dimensional calorimeter according to an embodiment of the present invention; Figure 3 This is a schematic cross-sectional view of the three-dimensional calorimeter according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of a calorimetric sensing component according to an embodiment of the present invention.

[0019] Explanation of reference numerals: 10, Equipment base; 20, Heating tank; 30, Heat equalization block; 40, Thermal sensing component; 41, Sensor end cap; 42, Inner liner support; 43, Thermoelectric generator; 44, Elastic clamping component; 50, Mechanical refrigeration component; 60, Composite insulation layer; 70, Adjustable speed fan.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0023] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0025] This invention provides a wide-temperature-range three-dimensional calorimeter control method based on mechanical refrigeration and thermoelectric generators, which is implemented in a corresponding three-dimensional calorimeter hardware system. The calorimeter hardware uses a base as the installation reference, with a heating barrel vertically fixed to the base and a high thermal conductivity homogenizing block coaxially arranged inside. A spiral circulating refrigeration pipe is embedded on the outside of the heating barrel, connected to an external refrigeration unit to form a mechanical refrigeration system. The heating barrel and refrigeration pipe are covered with a double-layer insulation structure to reduce environmental thermal interference. An adjustable-speed fan is installed at the bottom of the heating barrel, blowing air towards the bottom of the homogenizing block. A calorimetric sensing component is sealed at the top of the heating barrel, housing a three-dimensionally distributed thermoelectric generator and an elastic clamping structure. A temperature sensor is embedded in the center of the homogenizing block. All sensing and actuating components are connected to an external control module, and the control method enables coordinated regulation.

[0026] like Figures 1-4 As shown, the complete execution flow of this control method is as follows: Pre-run calibration phase: The entire device is installed on the device base 10. After the device is started, the pre-run calibration steps are performed first: the reference temperature is set through the external control module, the device is controlled to run for a preset time, and after the device status is stable, the baseline data of the temperature sensor is collected to complete the temperature drift calibration; at the same time, a blank experiment is performed, and the preset detection time is run in the absence of samples to collect the baseline signal of the thermoelectric generator 43, calculate the system heat loss value under the current environmental conditions, and update the calibrated parameters to the control parameter library to provide an accurate calculation reference for subsequent detection.

[0027] Users can set the target detection temperature and temperature control accuracy threshold through the human-machine interface of the external control module, and can also select the corresponding detection mode, including isothermal calorimetry, linear heating calorimetry, and linear cooling calorimetry. In the linear heating and cooling mode, the heating / cooling rate can be set, with a rate range of 0~2℃ / min.

[0028] During equipment operation, a temperature sensor embedded in the geometric center of the heat-dissipating block 30 continuously collects the actual temperature of the detection area. This temperature sensor is a PT1000 platinum resistance temperature sensor with an accuracy class of 0.1 and an embedding depth of 40mm. Thermal paste is filled between the sensor and the mounting hole wall to completely eliminate assembly gaps, ensuring rapid heat conduction to the sensing element, with a temperature signal feedback delay ≤0.1s. The temperature signal is transmitted to the acquisition unit of the external control module via a four-core shielded cable. Grounding the shielding layer effectively reduces environmental electromagnetic interference and ensures the accuracy of the temperature signal.

[0029] In this application, the calorimetric sensing component 40, which is located at the top opening of the heating barrel 20, is the core unit for realizing Calvet three-dimensional calorimetric detection. It adopts a modular design and mainly includes a sensor end cap 41, an inner liner bracket 42, multiple thermoelectric generator plates 43, and an elastic clamping component 44. The sensor end cap 41 can be precisely connected to the top of the heating barrel 20 via a positioning pin and a snap-fit ​​structure, allowing for assembly and disassembly without specialized tools. The inner side of the end cap has a mounting base and a wire groove for neatly storing signal wires, preventing tangling and signal interference. The inner liner bracket 42 is made of aluminum alloy with excellent thermal conductivity and has a cross-shaped three-dimensional bracket structure, including a central support column and multiple sensor unit mounting arms extending radially and evenly along the central support column. The mounting arms are distributed along the three-dimensional spatial direction, and each mounting arm has a snap-fit ​​protrusion at its end, which can engage with the snap-fit ​​groove on the inner side of the sensor end cap 41 for quick assembly. Each mounting arm has a mounting slot for a thermoelectric generator 43 on its inner surface. The size of the mounting slot matches the shape of the thermoelectric generator 43, and a thermally conductive silicone layer is provided at the bottom of the slot. The thermoelectric generator 43 is embedded in the mounting slot, and the thermally conductive silicone layer fits tightly to the bottom of the slot, ensuring efficient heat conduction. Multiple thermoelectric generators 43 are evenly distributed in three-dimensional space, each corresponding to a different spatial direction, forming a three-dimensional calorimetric detection array. This array can collect the thermal effect conducted by the uniformly heated block 30 from all directions, eliminating blind spots and biases in single-direction detection. The thermoelectric generator 43 operates based on the Seebeck effect, directly converting the temperature difference between the two ends into a voltage signal. Compared with traditional thermocouples, it has higher detection sensitivity, and different models can be selected according to the detection temperature range to adapt to different operating temperature ranges. The elastic clamping element 44 is a stainless steel annular wave-shaped spring sheet, fitted onto the central support column of the inner liner bracket 42, located between the sensor end cover 41 and the inner liner bracket 42. When the sensor end cover 41 is fastened and fixed to the heating barrel 20, the elastic clamping element 44 is compressed, generating a continuous and stable axial preload force, pushing the inner liner bracket 42 to fit against the heat equalization block 30, so that the heated surface of the thermoelectric generator 43 is in close contact with the surface of the heat equalization block 30, effectively reducing contact thermal resistance, and at the same time offsetting the assembly gap caused by equipment vibration and temperature deformation, ensuring the stability of heat conduction and the reliability of detection results. Copper signal wires are welded to the electrodes of the thermoelectric generator 43. The wires are laid along the wire groove inside the mounting arm and central support column of the inner liner bracket 42, and finally led out from the wire hole of the sensor end cover 41 to the external control module.

[0030] Furthermore, the external control module calculates the difference between the collected actual temperature and the set target temperature, and uses a closed-loop control algorithm combining PID and fuzzy control to output adjustment commands to dynamically adjust the heating and cooling power. The specific control logic is as follows: Temperature control: When the actual temperature is lower than the target temperature, the controller outputs a PWM pulse width modulation signal to the heating unit to increase the heating power of the electric heating wire inside the heating chamber 20; simultaneously, the fan speed is matched synchronously according to the temperature difference to accelerate heat diffusion within the chamber. If the target temperature is lower than room temperature, the cooling unit is activated first for rapid pre-cooling. Once the chamber temperature drops to near the target temperature, it switches to a low-power heating fine-tuning mode to avoid temperature fluctuations caused by over-cooling and ensure temperature control accuracy in the low-temperature range.

[0031] Cooling control: When the actual temperature is higher than the target temperature, the controller starts the refrigeration unit, driving the environmentally friendly refrigerant to complete the evaporation and heat absorption cycle within the spiral circulation refrigeration pipe, carrying away heat from the cavity to achieve cooling; simultaneously, the fan speed is increased to accelerate the uniform diffusion of cooling energy within the cavity. If the target temperature is higher than room temperature and the difference between the actual temperature and the target temperature is ≤5℃, the refrigeration unit is not started; instead, the temperature is corrected by reducing the heating power and coordinating with fan cooling, reducing temperature shocks caused by the start-up and shutdown of the refrigeration system and improving temperature stability.

[0032] Temperature control: When the actual temperature enters the target temperature accuracy range, the controller maintains the current heating power, cooling power and fan parameters, and makes minor power corrections based on real-time feedback from the temperature sensor to offset temperature fluctuations caused by environmental thermal interference, so that the cavity temperature remains stable within the temperature control accuracy threshold range.

[0033] In this application, throughout the temperature control process, the external control module synchronously regulates the speed of the adjustable fan 70. The fan speed adjustment range is 0~3000 r / min, and the speed is dynamically positively correlated with the heating rate and cooling rate. The fan outlet faces the bottom of the heat-monitoring block 30, driving the airflow to rise and circulate along the axial ventilation groove on the side of the heat-monitoring block 30, enhancing the circumferential heat exchange efficiency of the heat-monitoring block 30, accelerating the uniform diffusion of heat or cold, effectively reducing the temperature gradient on the surface of the heat-monitoring block 30, and improving temperature uniformity and temperature control response speed. The fan is installed using a vibration-damping structure to avoid operational vibration interfering with the calorimetry detection signal.

[0034] Once the cavity temperature stabilizes and meets the temperature control accuracy requirements, the calorimetric detection process begins. The container holding the sample is placed at the center of the top surface of the homogenizing block 30, ensuring tight contact with its surface. The thermal effect generated by the physical or chemical changes in the sample is uniformly conducted through the homogenizing block 30 to multiple sets of thermoelectric generators 43 arranged in three dimensions. These thermoelectric generators 43 are arranged along the x, y, and z three-dimensional coordinate axes, respectively. Each set of thermoelectric generators 43 is continuously subjected to axial preload through an elastic pre-compression component, maintaining tight contact with the heat-conducting surface of the homogenizing block 30, eliminating contact gaps caused by vibration and temperature deformation, and ensuring stable heat conduction. Based on the Seebeck effect, the thermoelectric generators 43 generate a temperature difference at their two ends due to heat conduction, thereby outputting a weak voltage signal corresponding to the temperature difference. The signal is transmitted via shielded wires to the 16-bit high-precision ADC acquisition unit of the external control module for analog-to-digital conversion.

[0035] Furthermore, the external control module processes and calculates the acquired three-dimensional temperature difference voltage signal, as follows: Signal preprocessing: The original voltage signal of each thermoelectric generator 43 is amplified and digitally filtered to remove signal noise caused by environmental interference and extract the effective thermoelectric voltage signal.

[0036] Unidirectional temperature difference calculation: Based on the formula U=α×ΔT×N, the temperature difference value ΔT corresponding to each direction is calculated by reverse calculation; where α corresponds to the Seebeck coefficient of the thermoelectric generator 43, and N is the number of thermocouple pairs of the thermoelectric generator 43. The parameters are pre-entered into the control module.

[0037] Three-dimensional data fusion: The temperature difference values ​​in the x, y, and z directions are weighted and fused. The weights are assigned based on the heat transfer path characteristics of each direction to eliminate blind spots and system biases in single-direction detection, and obtain the comprehensive temperature difference ΔTs.

[0038] Calorific value calculation: The calorific value Q of the sample is calculated using the formula Q=k×S×ΔTs×t-Q0; where k is the combined thermal conductivity of the uniform heating block 30 and the sensing module, S is the effective contact area between the sample container and the uniform heating block 30, t is the calorimetric detection time, and Q0 is the system heat loss value. The parameters k, S, and Q0 are all obtained through pre-calibration using standard samples. Indium is used as the standard substance for calibration. The system heat loss Q0 is determined through a blank experiment without a sample. Within the operating range of -80℃ to 300℃, Q0≤5J.

[0039] Full-temperature-range temperature compensation: During the calculation process, the external control module calls the pre-stored corresponding temperature compensation coefficient according to the current working temperature range to correct the output signal and calculation results of the thermoelectric generator 43, eliminate the influence of temperature range changes on the performance of the sensing element, and ensure the detection accuracy across the entire temperature range.

[0040] Results output and storage: The calculated calorific values ​​such as heat output, heat flux density, and enthalpy change are displayed in real time on the human-computer interaction interface and stored in the local storage unit. They can also be exported to external devices for further analysis via an interface.

[0041] In addition, the three-dimensional calorimeter provided in this application also includes a mechanical refrigeration assembly 50, which is composed of a circulating refrigeration pipe and an external refrigeration unit. The circulating refrigeration pipe is made of T2 copper, which has excellent thermal conductivity, enabling efficient heat exchange between the refrigerant and the heating tank 20. It also possesses good plasticity and corrosion resistance, making it easy to process into a spiral structure and resistant to long-term refrigerant corrosion. The circulating refrigeration pipe has a spiral layout, with its diameter precisely matching the outer diameter of the heating tank 20. This layout maximizes the contact area between the refrigeration pipe and the heating tank 20 while preventing pipe stacking from hindering heat transfer.

[0042] The circulating refrigeration pipe is embedded in the spiral groove on the outside of the heating tank 20, with thermally conductive silicone filling the gaps to achieve a seamless fit, further improving heat exchange efficiency. Both the inlet and outlet ends of the circulating refrigeration pipe are welded with standard stainless steel flanges. The flanges are connected to the copper pipes using silver brazing to ensure welding strength and sealing. A sealing gasket is placed between the flange interface and the connecting pipe of the external refrigeration unit, and the connection is secured with bolts. After assembly, an airtightness test is required to ensure no refrigerant leakage. During operation, the external refrigeration unit drives the environmentally friendly refrigerant to complete a refrigeration cycle within the circulating refrigeration pipe, involving evaporation and heat absorption, compression, condensation and heat release, and throttling. On one side of the cavity, the liquid refrigerant evaporates and absorbs heat from the heating tank 20 and the uniform heating block 30, achieving active cooling of the cavity. Combined with the heating function of the heating tank 20, arbitrary temperature adjustment within a wide range can be achieved.

[0043] The outer surface of the circulating cooling pipe and heating tank 20 is entirely covered with a composite insulation layer 60 to block heat exchange between the interior and exterior environments, reducing the interference of ambient temperature fluctuations on the detection area. The composite insulation layer 60 employs a double-layer structure: the inner layer is aerogel felt with lower thermal conductivity, allowing it to tightly adhere to the outside of the circulating cooling pipe and conform to the spiral shape of the pipeline; the outer layer is aerogel board with sufficient structural strength to form a stable protective shell. The inner aerogel felt and outer aerogel board are bonded together with a high-temperature resistant adhesive, applied evenly to avoid air bubbles and wrinkles. High-temperature sealant is filled at the seams of the composite insulation layer 60, as well as at the connections between the insulation layer and the heating tank 20 and the equipment base 10, eliminating heat leakage channels and forming a sealed, insulated cavity that significantly improves the stability of the internal temperature.

[0044] Example 1: Calorimetric Detection Control of Standard Substances at Room Temperature (25℃) In this embodiment, the target temperature is set to 25℃, the temperature control accuracy threshold is ±0.2℃, the sample to be tested is 0.1g of standard metallic indium, and the detection mode is isothermal calorimetry. The control process is as follows: after performing pre-run calibration, the target temperature is set to 25℃, and the temperature sensor collects the center temperature of the uniform heating block 30 in real time; the initial actual temperature is close to the target temperature, and the controller uses a combination of low-power heating fine-tuning and fan cooling to regulate the temperature, with the fan speed set to 2000r / min; after about 8 minutes, the temperature stabilizes at 25±0.2℃, and the maximum temperature difference on the surface of the uniform heating block 30 is 0.3℃. After the sample is placed in the circuit, the three-dimensional thermoelectric generator 43 synchronously collects the voltage signal of the phase transition process. After preprocessing, temperature difference calculation, three-dimensional fusion, and heat generation calculation, the final sample melting heat detection result is obtained with a deviation of 0 from the standard value, and the detection error is ≤±0.5%; the signal fluctuation during the detection process is ≤±0.05mV, the response output voltage of the thermoelectric generator 43 to a 1℃ temperature difference is 0.074V, the response time is 0.5s, and it has excellent detection sensitivity.

[0045] Example 2: Detection and control of epoxy resin reaction heat at medium and high temperatures (150℃) In this embodiment, the target temperature was set to 150℃, the temperature control accuracy threshold was ±0.3℃, the sample was epoxy resin with mixed curing agent, and the detection mode was isothermal calorimetry. The control process was as follows: after pre-run calibration, the target temperature was set to 150℃. If the actual temperature was lower than the target value, the controller output a PWM signal to increase the heating power at a rate of 3℃ / min, and the fan speed was simultaneously increased to 2500r / min to accelerate heat diffusion. After about 10 minutes, the temperature stabilized at 150±0.3℃, and the maximum temperature difference on the surface of the uniform heating block 30 was 0.4℃. After the sample was placed in the container, the three-dimensional thermoelectric signal of the curing reaction process was collected. The total heat generation and peak heat release rate of the epoxy resin curing reaction were calculated. The detection results were compared with those of a professional differential scanning calorimeter, and the error was ±0.7%. The response time of the thermoelectric generator 43 was 0.4s, and the signal fluctuation under high temperature conditions was ≤±0.05mV, indicating good stability.

[0046] Example 3: Phase change heat detection and control of phase change materials at low temperature (-50℃) In this embodiment, the target temperature was set to -50℃, the temperature control accuracy threshold was ±0.3℃, the sample under test was a low-temperature phase change material, and the detection mode was isothermal calorimetry. The control process was as follows: after pre-run calibration, the target temperature was set to -50℃. Since the target temperature was lower than room temperature, the controller first started the refrigeration unit for pre-cooling, and the fan speed was simultaneously increased to 3000 r / min to accelerate the diffusion of cold energy. When the temperature approached -50℃, it switched to a low-power heating fine-tuning mode. After about 12 minutes, the temperature stabilized at -50±0.3℃, the maximum temperature difference on the surface of the uniform heating block 30 was 0.5℃, and there was no obvious heat leakage or frost phenomenon. After the sample was placed, the endothermic signal of the phase change process was collected. After full-temperature range compensation correction, the phase change temperature and latent heat of phase change were calculated and compared with the detection results of the low-temperature calorimetry standard device. The error was ±0.9%. The response time of the thermoelectric generator 43 was 0.6s, and the output signal was stable in the low-temperature environment, verifying the detection reliability in the low-temperature range.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator, characterized in that, The wide-temperature-range three-dimensional calorimeter control method based on mechanical refrigeration and thermoelectric generator is applied to a three-dimensional calorimeter. The three-dimensional calorimeter includes a device base, a heating barrel, a heat equalization block, a calorimetric sensing component, a mechanical refrigeration component, a temperature monitoring unit, and an external control module. The heating barrel is vertically fixed on the device base, the heat equalization block is coaxially housed in the internal cavity of the heating barrel, the calorimetric sensing component is sealed at the top opening of the heating barrel, and the mechanical refrigeration component is disposed outside the heating barrel. The wide-temperature-range three-dimensional calorimeter control method based on mechanical refrigeration and thermoelectric generator includes: S1. Set the target detection temperature and temperature control accuracy threshold through an external control module; S2. The actual temperature of the detection area of ​​the heat-uniform block is collected in real time by a temperature sensor embedded in the geometric center of the heat-uniform block, and the temperature signal is transmitted to the external control module. S3. The external control module compares the difference between the actual temperature and the target temperature, and uses a closed-loop control algorithm to dynamically adjust the heating power of the heating barrel and the cooling power of the spiral circulation cooling pipe to achieve the adjustment of the cavity temperature. S4. During the temperature control process, the external control module synchronously adjusts the speed of the adjustable fan, driving the airflow inside the cavity to circulate along the heat equalization block, accelerating heat diffusion and temperature uniformity. S5. After the cavity temperature stabilizes, the sample to be tested is placed on the surface of the uniform heating block. Multiple sets of thermoelectric generators distributed in three-dimensional space synchronously collect the temperature difference voltage signal generated by the thermal effect of the sample and transmit it to the external control module. S6. The external control module performs fusion calculations on the three-dimensional temperature difference and voltage signals, combines them with pre-calibrated parameters to obtain the calorimetric parameters of the sample under test, and outputs and stores them.

2. The control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator according to claim 1, characterized in that, In step S3, the closed-loop control algorithm is specifically as follows: When the actual temperature is lower than the target temperature, the output PWM pulse width modulation signal increases the heating power and synchronously matches the fan speed to accelerate heat dissipation. If the target temperature is lower than the room temperature, the refrigeration unit is started first for pre-cooling. After the temperature approaches the target temperature, the mode of fine-tuning the heating power is switched. When the actual temperature is higher than the target temperature, the refrigeration unit is started to drive the refrigerant to evaporate and absorb heat in the spiral circulation refrigeration pipe to cool down. At the same time, the fan speed is increased to accelerate the diffusion of cold energy. If the target temperature is higher than the room temperature and the temperature difference is ≤5℃, the temperature is adjusted back by reducing the heating power and combining it with fan heat dissipation. Once the actual temperature reaches the target temperature range, the current heating, cooling, and fan parameters are maintained, and minor power adjustments are made based on temperature feedback to keep the temperature stable.

3. The control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator according to claim 1, characterized in that, In step S2, the temperature sensor is embedded to a depth of 40mm in the center of the heat-equalizing block, and thermal grease is filled between the sensor and the mounting hole wall to eliminate gaps.

4. The control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator according to claim 1, characterized in that, In step S5, multiple sets of thermoelectric generators are arranged along the three-dimensional coordinate axes of x, y, and z. Each set of thermoelectric generators is kept in thermally conductive contact with the surface of the heat-equalizing block by an elastic pre-compression component. The thermoelectric generators convert the temperature difference between the two ends into a voltage signal, which is transmitted to the external control module via a shielded wire.

5. The control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator according to claim 4, characterized in that, In step S6, the calorimetric data processing specifically includes: The raw voltage signal of each thermoelectric generator is amplified and filtered, and the temperature difference value in the corresponding direction is obtained according to the formula. ; in, denoted as Seebeck's coefficient for the thermoelectric generator, and N is the number of thermocouple pairs in the thermoelectric generator.

6. The control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator according to claim 5, characterized in that, In step S6, the calorimetric data processing specifically includes: The temperature difference values ​​in three dimensions are weighted and fused to eliminate detection bias in a single direction, resulting in a comprehensive temperature difference. ; According to the formula Calculate the calorific value Q of the sample being tested; Where k is the combined thermal conductivity of the heat exchanger and the sensing module, S is the effective contact area between the sample and the heat exchanger, and t is the calorimetric detection time. The predicted system heat loss value; The overall thermal conductivity k, effective contact area S, and system heat loss are mentioned. All were obtained through pre-calibration using standard samples, and the system heat loss was... The results were determined using a blank experiment without samples, within the temperature range of -80℃ to 300℃. .

7. The control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator according to claim 1, characterized in that, Step S6 also includes a full-temperature-range temperature compensation step: The external control module uses the temperature compensation coefficient of the corresponding temperature zone to correct the output signal of the thermoelectric generator based on the current operating temperature zone.

8. The control method for a wide-temperature-range three-dimensional calorimeter based on mechanical refrigeration and thermoelectric generator according to claim 1, characterized in that, Before step S1, the wide-temperature-range three-dimensional calorimeter control method based on mechanical refrigeration and thermoelectric generator also includes a pre-run calibration step: After starting the equipment, set the reference temperature and run for a preset time to complete the temperature drift calibration. At the same time, measure the system heat loss value under the current environmental conditions through a blank experiment and update it to the control parameter library.

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