A Methodology for Modeling Photocatalytic Reactors,Application to the Degradation of Formaldehyde

Abstract

This article dealt with the photocatalytic oxidation of formaldehyde, a representative indoor contaminant contained in air. A numerical model was developed for analyzing the degradation of formaldehyde based on experimentally estimated kinetic parameters. This was achieved by constructing two different configuration reactors operating under kinetic control regime and different steady conditions. The radiation and velocity fields of the reactors were simulated using computational fluid dynamics (CFD) methods. The reactors were installed on an external recirculation loop, and the processed air was reintroduced into a 1.95 m³ environmental chamber. The geometry design made the overall conversion of folded-plate reactor increase almost 40% relative to the plate reactor under a typical run. Studies also found that the overall conversion of formaldehyde showed good agreement between model predictions and experimental performances. The removal performance in the folded-plate reactor was obviously improved by enlarging the reaction area, increasing the residence time, and enhancing the radiation interchange. The relative high degradation efficiency was observed at relatively low relative humidity. The simulation results depicted that the radiation intensity was nearly uniformly increasing with distance along the surface, the velocity distribution was uniform in general, and most of the air passed through the triangular channel from the upper portion. The numerical model and CFD simulations could address a better reactor design and allow a better understanding of photocatalytic processes.