Numerical Study on Reduction of Ambient NOx Concentration by a Flow-through ACF (Activated Carbon Fibers) Fences

Toshihiro Kitada,Makoto Nagano,Takao Kanzaki,Takaaki Shimohara,Masaaki Yoshikawa

doi:10.15344/2456-351x/2017/131

Toshihiro Kitada, Makoto Nagano + Show 3 more

Open Access

https://doi.org/10.15344/2456-351x/2017/131

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Abstract

A method to use fences filled inside with activated carbon fibers (ACF) is presented for reduction of high NO2 concentration in urban atmosphere without excess energy use. Polluted air mass in road space moves with natural- and car-induced- winds to contact with- and to flow through- ACF fences, and the ACF layer removes these pollutants. Two parameters determining the performance of the ACF fences in terms of NOx abatement were identified as (1) resistance coefficient of the ACF layer to air flow, and (2) chemical reactivity of ACF layer for NOx removal. By varying these two parameter values in their ranges obtained by laboratory experiments, the reduction of NOx concentration at roadside by the ACF fences was numerically evaluated under an idealized situation in which two cases were considered; one is the double-fences placed at both sides of road and the other is single fence set at downwind side of the road. The results showed that in both cases these “energy-free” equipment can decrease NOx concentration by 15~55% at roadside. Furthermore, it was indicated that in the double-fence case the ACF fence with lower permeability (larger resistance coefficient) shows higher reduction of NOx, while in the single fence case higher permeability reduces NOx more.

Highlights

In Japan NO2 and NOx nearby heavy traffic road can still be locally high [1] in spite of continuously strengthened car emission regulation
This paper evaluates a new method which uses fences filled inside with activated carbon fibers (ACF) to decrease high NO2 and NOx concentrations in urban atmosphere without excess energy use
Two varied based on parameters characterizing ACF fence, the laboratory experiments described kc in the section 3

Summary

Introduction

In Japan NO2 and NOx nearby heavy traffic road can still be locally high [1] in spite of continuously strengthened car emission regulation. For evaluation of the performance of ACF fences in NOx concentration abatement, a set of non-thermal flow equations and advection-diffusion equation of air pollutant were applied with a standard k-ε turbulence model [8,9].

Results

Conclusion