Optimization of the airflow organization in the photocatalytic Trombe wall with numerical model

Abstract

The utilization of photocatalytic technology for the degradation of indoor volatile organic compounds (VOCs) offers the advantages of environmental friendliness, harmlessness and absence of secondary pollution. Integrating photocatalytic technology with the Trombe walls represents an effective form of building-based photocatalysis. However, there is an urgent need to improve the purification performance of photocatalytic Trombe walls. To address this issue, the impacts of co-catalysts and airflow organization on the degradation efficiency of indoor formaldehyde were investigated. TiO₂ with different co-catalysts and ratios were employed. The TiO₂-3% tourmaline achieved a 28.7% degradation rate within 1 h, exhibiting a 24.7% improvement compared to pure TiO₂. Furthermore, the impact of air layer structure on the airflow organization and photocatalytic performance was analysed using experiment and numerical model. By symmetrically arranging two vertical ribs (5 cm wide and spaced 12 cm apart) on the collector plate surface, the formaldehyde degradation rate reached 36.7%. Moreover, a quantitative analysis was conducted to optimize the air layer structure by examining the correlation between airflow distribution and indoor VOC degradation. The formaldehyde degradation rate reached 42.0% within one hour when the air layer was arranged with three spoiler plates at the upper middle of the collector plate surface.