Liquid backmixing in oscillatory flow through a periodically constricted meso-tube

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• 作者：N. Reis ; A.A. Vicente ; J.A. Teixeira
• 关键词：Backmixing ; Smooth-periodic constrictions ; Oscillatory flow ; Meso-tube ; Liquid flow ; Continuous
• 刊名：Chemical Engineering and Processing
• 出版年：2010
• 出版时间：July 2010
• 年：2010
• 卷：49
• 期：7
• 页码：793-803
• 全文大小：802 K

文摘

This paper deals with the measurement and modelling of axial liquid dispersion in a 4.5 mm internal diameter tube provided with smooth-periodic constrictions (meso-tube) in steady and oscillatory flow conditions. The residence time distribution (RTD) in the meso-tube was monitored for a range of fluid oscillation frequency (f) and amplitude (x₀) at laminar flow. The RTD response was modelled with three hydrodynamic models: (i) tanks-in-series, (ii) tanks-in-series with backflow and (iii) plug flow with axial dispersion. The steady flow through the meso-tube at flow rates up to 21.30 ml/min resulted in broad RTDs, mainly due to the parabolic velocity profile. The use of fluid oscillations allowed a fine-control of the axial liquid dispersion in the meso-tube due to generation of secondary flow in the regions between the constrictions. The axial dispersion coefficient D was reduced by up to 13-fold in comparison with the steady flow situation. Values of x₀ ≤ 1 mm and f = 10 Hz generally resulted in a maximum reduction in axial dispersion through, therefore maximum improvements in RTD. The tanks-in-series model was generally not capable of predicting RTDs in the meso-tube. The potential of this platform for the continuous, sustainable production of added-value products is herein demonstrated.