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 perfor...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.展开更多
采用稳态流动、应变扫描、频率扫描方法,研究CMC和羟丙基瓜尔胶以不同比例配合后在水溶液中的流变特性,并采用Ostwald de Waels方程对流动曲线进行拟合。试验结果表明,2%CMC水溶液为以粘性为主的流体,羟丙基瓜尔胶溶液为弱凝胶结构流体...采用稳态流动、应变扫描、频率扫描方法,研究CMC和羟丙基瓜尔胶以不同比例配合后在水溶液中的流变特性,并采用Ostwald de Waels方程对流动曲线进行拟合。试验结果表明,2%CMC水溶液为以粘性为主的流体,羟丙基瓜尔胶溶液为弱凝胶结构流体,符合在低剪切速率范围内符合Ostwald de Waels方程。在不同比例复配后溶液出现弱协同作用,表现在溶液弹性、凝胶性和剪切变洗能力增强,复配后的性能有利于改善单一采用CMC为牙膏配方的粘腻性、分散性不好等问题。展开更多
文摘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.
文摘采用稳态流动、应变扫描、频率扫描方法,研究CMC和羟丙基瓜尔胶以不同比例配合后在水溶液中的流变特性,并采用Ostwald de Waels方程对流动曲线进行拟合。试验结果表明,2%CMC水溶液为以粘性为主的流体,羟丙基瓜尔胶溶液为弱凝胶结构流体,符合在低剪切速率范围内符合Ostwald de Waels方程。在不同比例复配后溶液出现弱协同作用,表现在溶液弹性、凝胶性和剪切变洗能力增强,复配后的性能有利于改善单一采用CMC为牙膏配方的粘腻性、分散性不好等问题。
