Optimal design of novel honeycomb photocatalytic reactors for numerical analysis of formaldehyde degradation by CFD modeling

As an alternative to the investigation of photocatalysts, it is a potential approach to enhance the photocatalytic performance of the novel photocatalytic reactor by optimizing its geometric structure and reaction conditions. In this work, five different honeycomb photocatalytic reactors with a deflector and a porous airflow distribution plate were designed and a numerical simulation was performed based on computational fluid dynamics (CFD). The simulation results showed that a huge vortex appeared near the entrance of the original model and the velocity distribution inside the reactor was non-uniform, whereas these shortcomings could be effectively overcome when using the 45° deflector model (S-4) compared to the other models. Compared to S-1, the photocatalytic conversion rate of formaldehyde for S-4 was boosted by 7.29% at a flow velocity of 0.04 m s−1. In addition, it was found that the photocatalytic conversion rate of formaldehyde increased from 55.45 to 94.73% when the velocity decreased from 0.04 to 0.01 m s−1, and the photocatalytic removal rate of formaldehyde decreased from 94.73 to 70.05% as the relative humidity varied from 20 to 70%. Furthermore, when the irradiance increased from 45 to 265 mW cm−2, the photocatalytic conversion rate of formaldehyde improved by 10.78%. Overall, this work contributes to the design of the novel honeycomb reactor to acquire the optimized construction of the photocatalytic reactor.