Evaluation and application of dual-reactor chamber for studying atmospheric oxidation processes and mechanisms

Abstract

A new smog chamber with dual reactors was designed and constructed to study atmospheric oxidation processes that may form ozone or secondary organic aerosols (SOAs). The chamber consists of two 5 m3 fluorinated ethylene propylene (FEP) Teflon-film reactors housed in a thermally isolated enclosure, in which the temperature can be well controlled in the range of -10 to 40 °C. The influence of the light source on the gasphase oxidation mechanism of propene was investigated. The results showed that multiple ultraviolet (UV) light sources were better than traditional narrow-band black-lamp light sources. Preliminary experiments on propene and m-xylene photo-oxidation processes were performed. The results showed that the dual-reactor chamber can simulate the gas-phase oxidation processes that form ozone or SOAs, and can be used to determine the effects of various species by comparing experiments performed using different initial concentrations. The SOA yield data from m-xylene photo-oxidation under different NOx conditions were in good agreement with those from previous studies. This proves that the chamber can simulate gas-to-particle conversion processes. The dual reactors have the advantage of enabling experiments to be performed with only one key parameter being changed. This will help us to further understand the role of key factors in complex atmospheric pollution processes.