Slug and bubble flows in a flat sheet ultrafiltration module: Experiments and numerical simulation |
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Affiliation: | 1. Mechanical Engineering Department, Ferdowsi University of Mashhad, P.O. Box 917751111, Iran;2. Food Machinery Design Department, Research Institute of Food Science and Technology (RIFST), P.O. Box 91735-147, km 12, Asian Highway, Mashhad, Iran;1. State Key Laboratory Base of Eco-hydraulic Engineering in Arid Area, Xi''an University of Technology, Xi''an 710048, Shaanxi, China;2. State Key Laboratory of Multiphase Flow in Power Engineering, Xi''an Jiaotong University, Xi''an 710049, Shaanxi, China;1. Department of Civil Engineering, Lakehead University, Thunder Bay ON P7B 5E1, Canada;2. Department of Chemical Engineering, Lakehead University, Thunder Bay ON P7B 5E1, Canada |
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Abstract: | In this paper, the effect of gas bubbling including slug and bubble flows on enhancing shear force in an ultrafiltration (UF) process in a flat sheet module is investigated experimentally by image processing and numerically using the OpenFOAM software. In order to study characteristics of bubbles in the slug and bubble flows, the flat sheet module is analyzed by a video system facilitated with a high speed camera. The experimental results show that the average diameter of the slug flow is much larger than that of the bubble flow. The permeate flux for the slug and bubble flows is increased by 78% and 30%, respectively, compared to the case with no gas bubbling. The numerical results are shown to be in good agreement with those of the measurements both qualitatively and quantitatively. The results of simulations also demonstrate that although both flow patterns increase the shear stress by increasing the velocity gradient and/or vorticity, the shear stress induced by the slug flow is considerably larger. Therefore, the slug flow with a higher induced shear stress is more effective on the enhancement of the permeate flux in a UF process. |
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