Computational and experimental study of annular photo-reactor hydrodynamics

The performance of ultraviolet (UV) reactors used for water treatment is greatly influenced by the reactor hydrodynamics due to the non-homogeneity of the radiation field. Reliable modeling of the reactor flow structures is therefore crucial for the design process. In this study, the turbulent flow through two characteristic annular UV-reactor configurations, with inlets concentric (L-shape) and normal (U-shape) to the reactor axis, was investigated through computational fluid dynamic (CFD). The modeling results were evaluated with the velocity profiles from particle image velocimetry (PIV) experiments. The influence of mesh structure and density, as well as three turbulence models: Standard κ–ϵ, Realizable κ–ϵ, and Reynolds stress model (RSM), on the simulation results were evaluated. Mesh-independent solutions were achieved at mean cell volumes of 5 × 10−9 m3. The Realizable κ–ϵ displayed the best overall match to the experimental PIV measurements. In general, the CFD models showed a close agreement with the experimental data for the majority of the reactor domain and captured the influences of reactor configuration and internal reactor structures on the flow distribution. The validated CFD hydrodynamic models could be integrated with kinetic and radiation distribution models for UV-reactor performance simulation.