Abstract: An unsteady model of heat transfer in twin-screw extruder including barrel, polymer, and screws during preheating is established in order to predict the distribution and variation of temperature in extruder, and situation of melting of polymer in groove of screw. Numerical results show that temperature in the middle of barrel and close to the heating pipeline is higher than those in other places by the influence of distribution of heating pipeline as well as melting of polymer is faster. Average temperature of 8-type surfaces of barrel, polymer, and screw increases with preheating time. The temperature of 8-type surface of barrel during early preheating rises faster than those of others, and reaches steady fastest in end of the preheating, while the situation of screw is opposite to that of 8-type surface of barrel. The melting speed of polymer in barrel decreases with the preheating time cooperating with the change of temperature. The results have signification to guiding design and optimization of heating pipeline in barrel, and exactly predicting safety time of preheating.

Key words: Extruder, Melting, Numerical simulation, Polymer, Twin-screw