Author(s)

Alessandro Cubeddu, Cornelia Rauh, Antonio Delgado

Department of Food Biotechnology and Food Process Engineering, Faculty III—Process Science and Engineering, Berlin Institute of Technology, Berlin, Germany.
Institute of Fluid Mechanics, Technical Faculty, University of Erlangen-Nuremberg, Erlangen, Germany.

This paper aims to investigate a method to perform non-isothermal flow simulations in a complex geometry for generalised Newtonian fluids. For this purpose, 3D numerical simulations of starch based products are performed. The geometry of a co-rotating twin-screw extruder is considered. Process conditions concern high rotational speed (up to 1800 rpm), different flow rates (30, 40 and 60 kg/h) and water contents (22% and 36%), for a total of 54 simulations. To cope with the geometry complexity a Mesh Superposition Technique (MST) was adopted. The pseudoplastic behaviour of the fluid is taken into account by considering viscosity as function of shear rate (Ostwaldde Waele relationship) and temperature (Arrhenius law). Simulated temperature variations are compared with measurements at same process conditions for validation. Qualitative behaviour of temperature T and shear stress  along the screw are analysed and comparisons of different process conditions are presented. By these simulations a database is formed to develop a process control strategy for novel extruder operating points in food technology.

High Speed Extrusion; Non-Isothermal Numerical Simulation; Ostwald-De Waele Model

Cubeddu, A. , Rauh, C. and Delgado, A. (2014) 3D Thermo-Fluid Dynamic Simulations of High-Speed-Extruded Starch Based Products. Open Journal of Fluid Dynamics, 4, 103-114. doi: 10.4236/ojfd.2014.41008.