Modeling And Simulation Of Heat And Mass Transfer Enhancement In Micro Distillation System

The micro-distillation system refers to a distillation system composed of micro-channels with an inner diameter between 10 and 1000 μm.The flow characteristics and heat transfer characteristics of the fluid in the micro-channels are important prerequisites for the enhancement of heat and mass transfer in the micro-distillation system.In the distillation system,the trays of the distillation tower can quickly introduce the temperature imposed on the distillation tower into the mixed fluid,so that the light components in the mixed fluid can be separated into gas and liquid.In this research,the heat and mass transfer characteristics and phenomena of the micro-distillation system with simulated trays,i.e.rotating square columns,are analyzed,which will improve the heat transfer of the micro-distillation system.A 2D microchannel model was established.By changing the number,angle and position of square columns placed in the microchannel,the different forms of trays in the distillation tower were approximated.The research found that the vortex flow in the microchannel becomes more obvious,which leads to more obvious changes in temperature distribution,as the inlet flow rate increases in the low Reynolds.With the increase of the number of square pillars and the change of position,the temperature distribution are different.Meanwhile,when the number of square pillars is 2,the maximum mixing efficiency is 9.51%,and when the number of square pillars is 3,the maximum mixing efficiency is 11.49%.Then,the optimal design of the structure of the micro-distillation system is carried out.Three microchannel mass transfer models with different structures were simulated to obtain the velocity and composition distribution,and the obtained data were used to establish a simplified microchannel model through the identification method.After that,the efficiency difference between the mixing efficiency of the simulation model and the simplified model is used as the objective function,and the inlet conditions of the simplified model are optimized by genetic algorithm to obtain the best inlet arrangement.Finally,a 3D micro-distillation model is designed,and the VOF model and Mixture model are used to simulate,and the fluid flow characteristics.In order to separate the gas and liquid phases,a square cavity at the end of the microchannel is added,and gravity is used to separate the light and heavy components.Moreover,based on the idea of heat integration,a new micro-distillation system was designed.The heat carried by the outlet gas was used to reheat the microchannels to increase the temperature difference by using the optimal structure design.The results verified that the new system with increased reheat section was effective.