Computational modeling of UV photocatalytic reactors: model development, evaluation, and application

A computational model for simulating the performance of immobilized photocatalytic ultraviolet (UV) reactors used for water treatment was developed, experimentally evaluated, and applied to reactor design optimization. This model integrated hydrodynamics, species mass transport, chemical reaction kinetics, and irradiance distribution within the reactor. Among different hydrodynamic models evaluated against experimental data, the laminar, Abe-Kondoh-Nagano, and Reynolds stress turbulence models showed better performance (errors <5%, 12%, and 20%, respectively) in terms of external mass transfer and surface reaction prediction capabilities at different hydrodynamic conditions. A developed finite-volume-based UV lamp emission model was able to predict, with errors of less than 5%, near-and far-field irradiance measurements. Combining all these models, the integrated computational fluid dynamics (CFD)-based model was able to successfully predict the photocatalytic degradation rate of model pollutants (benzoic acid and 2,4-D) in various configurations of annular reactors and UV lamp sizes, over a wide range of hydrodynamic conditions (350 < Re < 11,000). In addition, the integrated model was used in combination with a Taguchi design of experiments method to perform reactor design optimization. Following this approach, a base case annular reactor design was modified to obtain a 50% more efficient design.