Study On Heat Transfer Performance And Optimization Of Melt Cooler With Porous Heat Transfer Inner Core

The melt cooler with porous heat transfer inner core was designed based on polymer melt flow and heat transfer characteristics.The structure is simple,and the main cooling component is easy to replace.Compared with the common shell-tube heat exchanger,it has a larger heat exchange area,higher heat exchange efficiency,smaller volume,and less pressure drop,which is a more efficient and ideal solution.In order to establish the calculation model of the total heat transfer coefficient of the melt cooler,the heat transfer process of the whole cooling system is divided into three sub-processes.The three sub-processes are the convective heat transfer between the melt and the porous part metal wall,heat conduction between the metal walls of the porous part and convective heat transfer between the porous part metal wall and the cooling oil.The calculation formula of heat transfer coefficient of each sub-process is obtained,and the calculation model of total heat transfer coefficient closer to the actual situation was derived.The pressure drop of the melt cooler is estimated according to the single melt hole pressure drop theory.In order to study the performance of the melt cooler,the FLUENT software was used to simulate the flow and heat transfer process of the cold and hot working fluid in the cooler.The DOE experimental scheme was developed to optimize the parameters of the melt hole diameter,axial melt hole gap,melt hole tilt angle and yield of the main factors affecting the heat transfer performance and pressure drop of the melt cooler.The results show that the heat transfer performance of the melt cooler can be increased by reducing diameter and the axial gap of the melt hole.The pressure drop of the melt cooler can be reduced by reducing the melt hole tilt angle,yield,and regulating the melt hole diameter.Compared with reducing the yield and axial gap of the melt hole,reducing the tilt angle of the melt hole and regulating the diameter of the melt hole are more conducive to reducing the pressure drop and improving the comprehensive performance of the melt cooler while satisfying the heat exchange performance.The calculation model of the total heat transfer coefficient was verified from three aspects of simulation,experiment and industrial test.The heat transfer model is verified by the correlation analysis results of the DOE test simulation group firstly.The results show that with the change of correlation factors,the simulated value of the total heat transfer coefficient is the same as the calculated value of the model.The absolute value of the numerical simulation value deviation of the total heat transfer coefficient is<8%relative to the calculated value of the heat transfer model.The melt cooling experiment was carried out by using the laboratory active melt cooler.The results show that with the change of yield,the experimental value of the total heat transfer coefficient is the same as the calculated value of the model.The absolute value of the experimental value of the total heat transfer coefficient is<5%relative to the calculated value of the heat transfer model,and the model is reliable.Based on the calculation model of total heat transfer coefficient,a melt cooler with porous heat transfer inner core was designed and tested.The results show that the absolute value of the test value of the total heat transfer coefficient is<15%relative to the calculated value of the heat transfer model.In summary,the calculation model of the total heat transfer coefficient is consistent with the actual heat transfer,and the heat transfer model is reliable.Using VB 6.0 software,the melt cooler design calculation software was developed to calculate the applicable production range for a specific structure,predict pressure drop,and guide the design and improvement of the melt cooler.