Research On The Reconstruction Of The Three-dimensional Temperature Field Of The Micro Reactor Based On The Infrared Thermal Image And The Probe Method

Reactor is widely used in various fields,such as analysis,chemical,agriculture,energy and so on.Temperature is one of the important parameters of the reactor,which is very important to research.At present,the reactor is becoming more and more microscale,and it is more difficult to measure temperature distribution accurately.Conventional contact measurement methods will not only interfere with the temperature field but also affect the internal structure.In this paper,an online measurement of thermal properties and surface temperature was proposed for solving the inverse problem of heat conduction of the adiabatic fixed-bed microreactor.Combined with infrared thermal imaging and probe,the three-dimensional temperature field was reconstruced.The main research contents are as follows:By means of computational fluid dynamics simulation software Fluent,the variation law of temperature field in adiabatic fixed bed microreactor was simulated.The simulation showed that the smaller the porosity of fixed bed,the higher the inlet temperature or the faster the flow rate,the more favorable the heat diffusion.The catalytic reaction was realized by the component transport model.The simulation found that increasing the flow rate,temperature,or concentration,the hydrogen peroxide decomposition accelerated,then the heat released increased,and the overall temperature of the fixed bed increased.In addition,the probe model was established.The theoretical simulation investigated the influence of the probe on the temperature field.The results showed that the probe has little influence on the temperature field.Only a little heat transfer accelerated in the contact part of the fluid and the probe.The maximum temperature rise was within 1 ?,which could be ignored.It can verify the effectiveness of the on-line measurement system.By designing and setting up the experimental device,the thermal probe combined with infrared thermal imaging method was used for on-line measurement.3D printing technology was applied,which made the fixed bed structure design more various and targeted,in line with the actual needs.Infrared casing structure was used to achieve adiabatic conditions,and reduce the interference to the infrared thermal imager.By adjusting the peristaltic pump and constant temperature tank to change the fluid parameters and changing the resin particles to change the porosity.It is found that when the initial temperature of the fixed bed reactor was 20 ? and the fluid was distilled water,under adiabatic conditions the faster the fluid flow rate,the higher the temperature,or the greater the porosity of the fixed bed,the greater the effective thermal conductivity of the fixed bed,the higher the overall temperature,and the shorter the time used to reach thestability of the temperature.The catalase was fixed on the filling carrier by adsorption method,and the temperature field changes of the micro-reactor were measured when the hydrogen peroxide was decomposed.The experimental results showed that under adiabatic conditions,with hydrogen peroxide entering the fixed bed,the heat was released under catalase catalysis,and the temperature rose until the heat produced was in equilibrium with the heat released.Increasing the flow rate or the reactant concentration will accelerate the decomposition of hydrogen peroxide to release more heat,the higher the temperature in the fixed bed.Increasing the porosity,the heat loss per unit time decreased and the overall temperature of the fixed bed increased.Finite element method was used to establish the positive thermal conductivity model,least square principle was used to establish the thermal conductivity inverse problem model,conjugate gradient method was used to solve the thermal conductivity inverse problem,the fixed bed surface temperature and effective thermal conductivity measured by online measurement method used by the thermal probe combined with infrared thermal imaging method,the internal temperature field of the reactor was retrieved by MATLAB.The results showed that the temperature change trend was consistent with the simulated temperature field and the experimental temperature field.Heat loss could cause the wall temperature measured in the experiment to be lower than the theoretical value,with a maximum error of 5.8%.The larger the flow velocity,the higher the inlet temperature,or the larger the particle size,the higher the overall temperature of the fixed bed.It could be seen that the fluid properties and fixed bed parameters are critical to heat transfer.A series of studies have shown that,based on infrared thermal imaging and probe method,the micro-reactor can calculate the three-dimensional temperature field distribution from the surface temperature with high accuracy.