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ModelingChristopher R. Schulz, P.E., DEECDM Inc.Denver, ColoradoCarrie L. Knatz, P.E. and Veronica OrtizCDM Inc.Carlsbad, CaliforniaJoseph YelpoSunlight Systems, IncAllendale, New JerseyIntroductionRecent research has demonstrated that computational fluid dynamics and irradiance modeling(referred to as CFD-i modeling in this paper) can be used to accurately predict the fluence (orUV dose) in flow-through UV reactors. For example, the Metropolitan Water District ofSouthern California (Mofidi, 2004) compared predicted CFD-i modeling and measuredvalidation testing results for a 3-mgd Calgon Sentinel reactor with four medium-pressure (MP)lamps. The model predicted validation results within 0.1 log reduction of MS-2 coliphage.Similarly, CFD-i modeling and biodosimetry testing results were compared for a 18-mgdWedeco K3000 reactor with low-pressure high-output (LPHO) lamps under various lamp powerand UVT conditions (Rokjer, 2002). The percent difference between predicted and measuredreduction equivalent dose (RED) using B. subtilis as the target organism, ranged from 5 to 20percent for CFD-i runs at ten different flow and water quality conditions. Due to its demonstratedaccuracy, CFD-i modeling is now routinely used by UV equipment suppliers for developing newor optimizing existing UV reactor designs. This paper presents CFD-i modeling results for a newUV reactor design being developed by Sunlight Systems, Inc. of Allendale, New Jersey fordrinking water disinfection applications. The results were related to: optimization of the UVBox reactor design; and, a comparison of the dose delivery and hydraulic efficiency of the UVBox reactor with an unbaffled annular reactor. CFD-i modeling was used to optimize the design of the UVBox reactor with respoect to: dose delivery (RED); residence time distribution (RTD); hydrodynamic flow patterns in the reactor; and, pressure drop across the reactor. Three UV reactor configurations were analyzed using CFD-i modeling: UVBox unbaffled reactor with 30-inch inlet/outlet flanges, rectangular vessel dimensions of30 inches wide by 30 inches high by 30 inches long and four MP lamps positionedperpendicular to flow; UVBox baffled reactor with the same vessel dimensions and lamp configuration as above, plussix angled flow deflector baffles positioned upstream and downstream of the lamps to directthe flow closer to the lamp sleeves and introduce flow recirculation patterns between the upstream and downstream baffles; and, annular unbaffled reactor with 30 inch inlet/outlet flanges and tubular vessel dimensions of 30 inch inlet/outlet flanges and tubular vessel dimensions of 30 inches long by 30 inches in diameter. Includes 7 references, tables, figures.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 14File Size: 1 file , 1.3 MB