Design and characterization of a new oxidation flow reactor for laboratory and long-term ambient studies

Abstract. Oxidation flow reactors (OFRs) are frequently used to study the formation and evolution of secondary aerosol (SA) in atmosphere have become valuable tools for improving accuracy model simulations depicting accelerating realistic atmospheric chemistry. Driven by rapid development OFR techniques increasing appreciation their wide application, we designed a new all-Teflon reactor, Particle Formation Accelerator (PFA) OFR, characterized it laboratory with ambient air. A series experiments were performed characterize (1) profiles reactor using computational fluid dynamics (CFD) simulations, (2) UV intensity distribution influence varying O3 concentration relative humidity (RH) on resulting equivalent OH exposure (OHexp), (3) transmission efficiencies gases particles, (4) residence time distributions (RTDs) particles both experimental verification, (5) production yield organic (SOA) from oxidation α-pinene m-xylene, (6) effect seed SA concentration, (7) air Riverside, CA, US. The response characteristics compared those smog chamber (Caltech) other reactors: Toronto Photo-Oxidation Tube (TPOT), Caltech Photooxidation Flow (CPOT), TUT Secondary Aerosol Reactor (TSAR), quartz aluminum versions Potential Mass (PAMs), Environment Climate Change Canada (ECCC-OFR). Our studies show that OHexp can be varied over range comparable OFRs; particle efficiency is 75 % size 50 200 nm, after minimizing static charge Teflon surfaces; penetration CO2 SO2 0.90 ± 0.02 0.76 0.04, respectively, latter which estimates LVOCs; near-laminar profile expected based CFD suggested RTD experiment results; m-xylene SOA yields 0.22 0.37, at about 3 × 1011 molec. cm−3 s exposure; mass ratio precursor gas has significant amount formed; during measurements when sampling formed was an average 1.8 times same time.