Assessing the degree of plug flow in oxidation flow reactors (OFRs): a study on a potential aerosol mass (PAM) reactor

摘要

Oxidation flow reactors (OFRs) have been developed to achieve high degrees ofoxidant exposures over relatively short space times (defined as the ratio ofreactor volume to the volumetric flow rate). While, due to their increaseduse, attention has been paid to their ability to replicate realistictropospheric reactions by modeling the chemistry inside the reactor, there isa desire to customize flow patterns. This work demonstrates the importance ofdecoupling tracer signal of the reactor from that of the tubing whenexperimentally obtaining these flow patterns. We modeled the residence timedistributions (RTDs) inside the Washington University Potential Aerosol Mass(WU-PAM) reactor, an OFR, for a simple set of configurations by applying thetank-in-series (TIS) model, a one-parameter model, to a deconvolutionalgorithm. The value of the parameter, N, is close to unity for every caseexcept one having the highest space time. Combined, the results suggest thatvolumetric flow rate affects mixing patterns more than use of our internals.We selected results from the simplest case, at 78 s space time with oneinlet and one outlet, absent of baffles and spargers, and compared theexperimental F curve to that of a computational fluid dynamics (CFD)simulation. The F curves, which represent the cumulative time spent in thereactor by flowing material, match reasonably well. We value that the use of a small aspect ratio reactor such as the WU-PAM reduces wall interactions; however sudden apertures introduce disturbances in the flow, and suggest applying the methodology of tracer testing described in this work to investigate RTDs in OFRs to observe the effect of modified inlets, outlets and use of internals prior to application (e.g., field deployment vs. laboratory study).