Modelling Flow and Heat Transfer in Co-Rotating Twin-Screw Extruders

Abstract

This work presents a modelling routine of co-rotating twin-screw extrusion, from hopper to die. The program accounts for a sequence of individual stages linked together by boundary conditions, namely starve-fed solids conveying, solids conveying under pressure, delay, melting, melt conveying without pressure and melt conveying under pressure. It predicts the evolution along the screw and die of temperature, shear rate, residence time, viscosity, mechanical power consumption, pressure and fill ratio. The results obtained showed adequate sensitivity to changes in operating conditions and screw geometry and are in agreement with current theoretical and experimental knowledge.

Application of evolutionary algorithms to the definition of the optimal twin‐screw extruder configuration for starch cationization

“…In previous studies [1, 2, 5, 6], the Ludovic© software, developed at CEMEF, was used for this purpose [4]. In this article, the program TwiXtrud, recently developed at University of Minho will be also adopted, as it takes into account the different physical steps occurring along the extruder [10]: (i) solids conveying without pressure; (ii) solids conveying under pressure; (iii) delay zone; (iv) melting (with high solids content); (v) melting (with low solids content); (vi) melt conveying under pressure, and (vii) melt conveying without pressure.…”

Engineering an efficient two-phase local search algorithm for the co-rotating twin-screw extruder configuration problem

“…As shown in Fig. 18 (2011) process steps is the following: (i) solids conveying without pressure; (ii) solids conveying under pressure; (iii) delay (formation of a melt film between the solids and the barrel); (iv) melting with a low liquid content; (v) melting with a low solids content; (vi) melt conveying under pressure; and (vii) melt conveying without pressure (Teixeira et al, 2007). The performance of a given screw configuration is evaluated through modeling of the polymer flow along the machine, i.e., predicting the axial evolution of the average and cumulative residence times, pressure, temperature, power consumption, average strain, specific mechanical energy (SME), viscosity, and channel degree of fill.…”

“…The sequence, nature, and intensity of the individual process steps will depend on the requirements of the compound to be prepared. The simulation software developed by the authors (Teixeira et al, 2007) comprises the various process steps developing along the extruder from hopper to die. Typically, the sequence of C. Teixeira et al / Intl.…”

“…18 (2011) 271-291 273 r 2010 The Authors. International Transactions in Operational Research r 2010 International Federation of Operational Research Societies process steps is the following: (i) solids conveying without pressure; (ii) solids conveying under pressure; (iii) delay (formation of a melt film between the solids and the barrel); (iv) melting with a low liquid content; (v) melting with a low solids content; (vi) melt conveying under pressure; and (vii) melt conveying without pressure (Teixeira et al, 2007). Figure 3 illustrates the corresponding physical models.…”

“…As mentioned above, the objective values are determined using a complex simulation program (Teixeira et al, 2007). The computation times that are required to evaluate one single screw configuration range between 1 and 3 min (measured on AMD Opteront 2216 dual-core processors running at 2.4 GHz with 2 MB L2-Cache), depending mainly on the number of restrictive elements considered for an instance.…”