Alternating mixing tabs in multifunctional heat exchanger-reactor
CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
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Streamwise vortices are used in many applications for mixing processes, fast chemical reactions and heat-transfer enhancement. In this work we studied experimentally and numerically the effects of vorticity field redistribution on the turbulence energy dissipation rate in a modified geometry of the high-efficiency vortex (HEV) mixer, in which the mixing tab arrays are periodically rotated by 45 degrees to better distribute the vorticity field. Attention focuses on the evolution and distribution of turbulence energy dissipation, since this describes quantitatively the drop breakup and turbulent micromixing mechanism, which controls fast chemical reactions. It is found that redistribution of the vorticity field locally intensifies turbulent micromixing relative to the classical HEV mixer, producing a local mixing intensification of up to 120%. In addition, the alternating vortex generator arrays improve homogenization of the turbulence field in the mixer. (C) 2009 Elsevier B.V. All rights reserved.