Study On Meltingand Heat Transfer In Melting Zone Of Co-rotating Twin Screw Extruders

Co-rotating twin screw extrusion has always played an important role inpolymer processing. The principles of materials' flow and heat transfer inmelting zone are valuable for design of screw configurations and selection ofoperational conditions. This paper has adopted Fluent to simulate mixing andmelting of screw elements and kneading blocks in co-rotating twin screwextruder. Heat transfer and flow of HDPE in the extruder's channel underdifferent technical conditions have been studied numerically. The influencesof screw configurations and technical conditions on melting have also beendiscussed, and methods to enhance melting result have been proposed.Numerical simulations have been carried out to study the melting processof solid particles in quasi-three dimensional flow channels. Deformation,melting and flow behaviors of the solid pellets in the melt have been simulated.The influences of screw configurations and technical conditions on meltinghave been studied. The inner heat and viscous dissipation, which contribute topellets' melting have been analysed comparetively. Numerical simulations have been carried out to study the melting processof solid particles in three dimensional flow channels. A number of solid pelletshave been put in the flow channel of melting zones. Melting process ofmultiple pellets has been revealed according to the computation of meltingtime. The influences of technical conditions on melting process have beenanalysed and the differences of heating and viscous dissipation have beencompared.Numerical simulations have been carried out to study material group'smelting process and mechanisms in screw element's melting zone, theinfluences that affect material group's extrusion and melting process havebeen discussed.Numerical simulations have been carried out to study the influence ofscrew configurations on mixing melting process. Kneading blocks and screwelement have been selected to find out the differences of materials'temperature rise, melting rate and energy consumption of two flow channels.Numerical studies of mixing and melting abilities of kneading blockshave been carried out. A configuration of kneading blocks with wide discs andsmall staggering angles has been taken as an example, to simulate thematerials' outlet temperature, outlet melt percentage, viscous energy and totalenergy, as the functions of feeding rate, screw speed, barrel temperature andoperational time. Quadratic regression functions obout technical conditionshave been obtained. The effects which technical conditions influence parameters representing melting abilities (i.e. materials' outlet temperatureand outlet melt percentage) and parameters representing energy consumption(i.e. viscous energy and total energy) have been simulated. Based on thediscussions of extreme energy consumption of melting process, methods topromote melting have been proposed by optimize screw configurations andtechnical conditions, which would provide guidance for the choice of screwconfigurations and technical conditions in industrial production.Experiments have been carried out to testify the influence of technicalconditions and screw configurations on melting process, by measuring themelt temperature and melt percentage in different screw configurations.Theexperiments results testify not only the results of numerical simulation but alsothe ralationships between melting process and factors.