The inactivation data for Escherichia coli are recorded for the three reactor geometries of Taylor-Couette flow and flow between either concentric cylinders or a square channel. All of the data are shown to be correlated with the assumption of plug flow. In particular, the effects of nonuniform radiation levels are accounted for by integration across the fluid channel as done previously. However, a new correction factor is introduced that is shown to be inversely proportional to the laminar, velocity boundary thickness to account for the effects of a concentration boundary layer of surviving pathogen. It has also been demonstrated that the common problems of nonuniform radiation levels and concentration boundary layer effects in UV reactors are largely eliminated with the use of Taylor-Couette flow. Moreover, the repetitive exposure of fluid parcels to a small number of lamps in the rotating Taylor-Couette flow decreases maintainance requirements compared to the hydrodynamic equivalent of cross-flow over a tube bank or lamp array. Over a 3-log reduction in the inactivation of E. coli was demonstrated compared to a conventional channel with the same radiation dosage. Moreover, greater than a 2-log reduction was evident compared to flow through concentric cylinders.
An analysis of thermal radiation effects on unsteady MHD free convective heat and mass transfer flow past a vertical porous plate immersed in a porous medium with time dependent suction in presence of magnetic field with viscous dissipation has been considered by employing shooting iteration technique along with fourth order RungeKutta integration scheme. Resulting non-dimensional velocity, temperature and concentration profiles are then presented graphically for different values of the parameters entering into the problem. Finally, the effects of the pertinent parameters on the skin-friction coefficient, the rate of heat transfer (Nusselt number) and the rate of mass transfer (Sherwood number), which are of physical interest, are exhibited in the tabular form.
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