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LABORATORY AND NUMERICAL INVESTIGATIONS OF RESIDENCE TIME DISTRIBUTION OF FLUIDS IN LAMINAR FLOW STIRRED ANNULAR PHOTOREACTOR
Citation:
SahleDemessie*, E, S. Bekele, AND U R. Pillai**. LABORATORY AND NUMERICAL INVESTIGATIONS OF RESIDENCE TIME DISTRIBUTION OF FLUIDS IN LAMINAR FLOW STIRRED ANNULAR PHOTOREACTOR. Presented at AIChE Conference, Indianapolis, IN, November 03 - 08, 2002.
Impact/Purpose:
To inform the public.
Description:
Laboratory and Numerical Investigations of Residence Time Distribution of Fluids in Laminar Flow Stirred Annular Photoreactor
E. Sahle-Demessie1, Siefu Bekele2, U. R. Pillai1
1U.S. EPA, National Risk Management Research Laboratory
Sustainable Technology Division, Cincinnati, Ohio 45268, U.S.A.
2The Boundary Layer Wind Tunnel Laboratory,
University of Western Ontario, Western Ontario University,
London, Ontario, Canada
Abstract
When gases flow through an annular photoreactor at constant rate, some of the gas spends more and less than the average residence time in the reactor. This spread of residence time can have an important effect on the performance of the reactor. This study tested how the residence time distribution (RTD) in an annular photoreactor with a magnetic stirrer at the bottom, is affected by the flow rate, different stirring rate and reactor length-to-diameter ratios. Pulse response studies with UV/VIS measurements were used to measure the RTD curve, and a dimensionless parameter L/Nd was used as a measure of the approach to plug flow. Numerical method was used to develop a model base on second order discritization and a convergence criteria of 1e-4 for all variables as laminar flow. Effects of reactor mixers in an annular photoreactor were simulated using a finite volume method (FLUENT). Steady state solution obtained by imposing the boundary condition of inlet velocity of the required flow rate outlet, outflow boundary condition adapted ( the value at the outlet are interpolated from the interior domain.). inside and outside surface of the cylinder specified a wall boundary condition ( no slip boundary condition) were used. A virtual fan having specific radial and axial flow velocities introduced at the inlet of the reactor to initiate swirl motion. Grids for the above simulations are generated using GAMBIT. The information would be useful to design and scale-up gas flow photoreactor that behave like stirred tanks in series or approach plug flow system.