ON THE MEASUREMENTS OF THE RADIAL TEMPERATURE DISTRIBUTION IN AN EXTRUDER CHANNEL

In single-screw extrusion it is not unusual to encounter large tempera ture variations within the screw channel, especially at high pumping r ates. These temperature variations result in nonhomogeneities that aff ect the quality of the final product. Although there have been numerou s efforts aiming at the simulation of the flow in the channel of a sin gle-screw extruder, and the prediction of important flow quantities, t here is hardly any published work in which the temperature distributio n in the screw channel was actually measured. Such measurements, if av ailable, would provide data by which computer simulations could be val idated. In the present study, a fast-response, cam-driven thermocouple system was developed and used to measure the radial temperature distr ibution in the screw channel. The measurements are carried out on a we ll-controlled, custom-built, single-screw extruder. Temperature profil es in the centerline of the screw channel were obtained for various op erating conditions of the machine. The data obtained revealed interest ing features of the flow as well as the dominant heat transfer mechani sms. The system as developed here can be improved to accommodate large r industrial applications. (C) 1994 John Wiley & Sons, Inc.