COOLING OF EXTRUDER STRANDS - EXPERIMENTS AND MODELING

Cooling of plastic strands in a waterbath has been investigated. A mat hematical model based upon the mechanisms of heat transport inside the plastic strands and heat transfer processes into the surrounding air has been developed. The resulting pellet temperature is calculated and compared with experimental data measured for three extruders of diffe rent size. The model describes the process fairly well. Experiments sh ow that cooling between the waterbath exit and cutter inlet is not neg ligible. Water evaporation, removal of excess water and radiative heat transfer determine the cooling in this region. This effect is charact erized by an overall heat transfer coefficient obtained from experimen tal data.