Influence of TiO_2-based photocatalytic coating road on traffic-related NO_x pollutants in urban street canyon by CFD modeling

摘要

The use of titanium dioxide (TiO_2) photocatalytic nanoparticles as road coating to trap and decompose air pollutants provides a promising technology to mitigate the harmful effects of vehicle emissions. However, there are few studies on computational fluid dynamics (CFD) simulations of the effect of NO_x photocatalytic oxidation in street canyon with TiO_2 nanoparticles as pavement coating. This study develop a CFD model with photocatalytic oxidation (PCO) reaction implemented for numerical simulation of NO_x abatement in an urban street canyon with TiO_2 coating, considering the effects of relative humidity (RH) (10-90%), and irradiance (10-40W · m~(-2)). Results show that TiO_2 coating road can effectively reduce nitrogen oxide (NO_x) concentration in the street canyon. The average nitric oxide (NO) and nitrogen dioxide (NO_2) concentrations in street canyon with TiO_2 coating road were reduced by 3.70% and 4.31 %, respectively, comparing with street canyon without TiO_2 coating. The irradiance and relative humidity had great effect on PCO reaction in street canyon with TiO_2 coating road. When the irradiance increased from 10W · m~(-2) to 40W · m~(-2) average NO conversion rose from 1.35% to 3.70%, and average NO_2 conversion rose from 2.43% to 4.31%. The average conversion of NO and NO_2 decreased from 5.11% to 2.54% and from 5.60% to 3.25%, respectively, when the relative humidity is varied from 10% to 90%. Results are useful to transport planners and road engineers who need to reduce NO_x concentrations in urban streets travelled by fossil fuel-powered vehicles. Method of the study can be considered by future research faced with different pavement construction and traffic environment.