Radiation modelling in the NETmix photocatalytic reactor: The concept of efficiencies in series

Abstract

This study focuses on the radiation modelling and evaluation of the efficiencies in series regarding the NETmix photocatalytic reactor, using As(III) oxidation to As(V) as a model reaction. The performance of the NETmix reactor was evaluated using two configurations: Front-side (FSI) and back-side (BSI) illumination. A CFD radiation modelling for the two configurations was complemented and analyzed with the concept of efficiencies in series. The outer geometrical, the inner geometrical, and the reaction photonic efficiency were considered and their contribution to the overall reactor performance was assessed. The reaction photonic efficiency was obtained through the experimental results of the As(III) oxidation under microscale illumination (UVA-LEDs), using catalyst thin-films (TiO2-P25) with different thickness in both reactor configurations. In a BSI mechanism, 71 % of the catalytic area is subject to a radiation flux between 250 and 450 W m-2, while in the case of a FSI mechanism, 70 % of the surface is illuminated with flux between 0 and 300 W m-2. In other words, even though FSI has a larger catalytic surface area (from 55.4 to 167.3 cm2 for BSI and FSI, respectively), it is worse or less illuminated since most of it corresponds to lateral walls. Along with the reaction photonic efficiency, it was possible to obtain a 2-fold increase in the global efficiency factor when FSI mechanism is used. Hence, the concept of efficiencies in series applied to radiation modelling allowed the identification of the main factors that influence the global reactor performance.