Modeling of melt conveying in a deep-channel single-screw cheese stretcher

Numerical simulation was performed to analyze flow field and heat transfer developed inside a deep-channel, single-screw cheese stretcher channel. Modifications to the traditional flat-plate model of single-screw extruder geometry were applied to address flight effects and channel curvature effects. The finite difference and finite element methods were used to obtain numerical solutions to the flow and energy equations. Isothermal and non-isothermal conditions were considered for Newtonian flow and non-Newtonian (power-law and Bird–Carreau models) fluids. The model-predicted velocity distributions and screw characteristic curves were tested using the published experimental data. For Newtonian fluids at screw speeds above 150 rpm, our model predicted volumetric flow rate was within 0.5% of the experimental data compared to the typical 50% overprediction by the existing models. Our model performed much better than the published models for the case of the non-Newtonian fluids also. The simulation results show that in a deep-channel cheese stretcher, the flight effect is more important than the curvature effect in terms of the overall volumetric flow rate. 2003 Elsevier Ltd. All rights reserved.