Computational fluid dynamics modeling and parameterization of the visible light photocatalytic oxidation process of toluene for indoor building material

Abstract

Poor indoor environmental conditions caused by the presence of gas-phase/aerosol-phase contaminants are thought to be potential triggers of illnesses, leading to productivity losses. In recent decades, the photocatalytic oxidation (PCO) process has attracted attention because of its potential to purify indoor air polluted with volatile organic compounds (VOCs), especially at low concentration levels. Titanium-dioxide (TiO2)-bound building materials have been extensively studied for the oxidation of indoor VOCs. In this study, kinetic studies were carried out to evaluate the PCO of toluene in the gas phase, over TiO2-bound building materials, using a 20l small test chamber. A Langmuir–Hinshelwood (L–H)-type model, for reproducing the PCO process over TiO2-bound building materials, was developed as a function of the toluene concentration, illumination intensity, and humidity levels. The parameters of the L–H model were determined using the hybrid identification procedure of computational fluid dynamics (CFD) simulations and a 20l small test chamber experiment. By using this hybrid identification method, PCO kinetic parameters were estimated with reference to the concentration in viscous-sub layer. Finally, CFD simulations were also carried out under the same boundary conditions as those used in the chamber experiments to evaluate the prediction accuracy.