Computational modeling of ultraviolet light-emitting diode (UV-LED) reactor for water treatment

The ultraviolet light emitting diode (UV-LED) has recently emerged as a new UV source. It offers design flexibility due to its small size and ability to alter its radiation profile. In view of the variety of design possibilities for a UV-LED reactor, a computational model could be of great value for simulating the reactor and providing insight into its performance. Given the UV-LED's ability to emit various radiation wavelengths and because it is a directional UV source, the challenges of simulation for UV-LEDs are greater than those for UV lamps, which typically have a single wavelength and an almost radial radiation profile. This study proposes a method of simulating UV-LED reactors in the Eulerian framework through the integration of the kinetic, hydrodynamic, and radiation models, representing UV-LED systems. Additionally, the concept of an ideal UV-LED system is proposed, which can provide insight into the efficiency of any UV-LED reactor design concept. The integrated model of reactor performance is evaluated through experimental studies of challenge organisms (e.g., Escherichia coli and MS2) in two UV-LED reactors under different operating conditions, including flow rates, flow regimes, radiant powers, and UV-LED configurations. The close agreement between the numerical predictions and experimental data demonstrates the ability of the proposed method to simulate UV-LED reactor performance.