scholarly journals Supplementary material to "Assessing the degree of plug flow in oxidation flow reactors (OFRs): a study on a Potential Aerosol Mass (PAM) reactor"

Author(s):  
Dhruv Mitroo ◽  
Yujian Sun ◽  
Daniel P. Combest ◽  
Purushottam Kumar ◽  
Brent J. Williams
2018 ◽  
Vol 11 (3) ◽  
pp. 1741-1756 ◽  
Author(s):  
Dhruv Mitroo ◽  
Yujian Sun ◽  
Daniel P. Combest ◽  
Purushottam Kumar ◽  
Brent J. Williams

Abstract. Oxidation flow reactors (OFRs) have been developed to achieve high degrees of oxidant exposures over relatively short space times (defined as the ratio of reactor volume to the volumetric flow rate). While, due to their increased use, attention has been paid to their ability to replicate realistic tropospheric reactions by modeling the chemistry inside the reactor, there is a desire to customize flow patterns. This work demonstrates the importance of decoupling tracer signal of the reactor from that of the tubing when experimentally obtaining these flow patterns. We modeled the residence time distributions (RTDs) inside the Washington University Potential Aerosol Mass (WU-PAM) reactor, an OFR, for a simple set of configurations by applying the tank-in-series (TIS) model, a one-parameter model, to a deconvolution algorithm. The value of the parameter, N, is close to unity for every case except one having the highest space time. Combined, the results suggest that volumetric flow rate affects mixing patterns more than use of our internals. We selected results from the simplest case, at 78 s space time with one inlet and one outlet, absent of baffles and spargers, and compared the experimental F curve to that of a computational fluid dynamics (CFD) simulation. The F curves, which represent the cumulative time spent in the reactor 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).


2017 ◽  
Author(s):  
Dhruv Mitroo ◽  
Yujian Sun ◽  
Daniel P. Combest ◽  
Purushottam Kumar ◽  
Brent J. Williams

Abstract. Oxidation flow reactors (OFRs) have been developed to achieve high degrees of oxidant exposures over relatively short space times (defined as the ratio of reactor volume to the volumetric flowrate). While, due to their increased use, attention has been paid to their ability to replicate realistic tropospheric reactions by modeling the chemistry inside the reactor, there is a desire to customize flow patterns. This work demonstrates the importance of decoupling tracer signal of the reactor from that of the tubing when experimentally obtaining these flow patterns. We modeled the residence time distributions (RTDs) inside the Washington University Potential Aerosol Mass (WU-PAM) reactor, an OFR, for a simple set of configurations by applying the tank-in-series (TIS) model, a one parameter model, to a deconvolution algorithm. The value of the parameter, N, is close to unity for every case except one having the highest space time. Combined, the results suggest that volumetric flowrate affects mixing patterns more than use of our internals. We selected results from the simplest case, at 78 s space time with one inlet and one outlet, absent of baffles and spargers, and compared the experimental F-Curve to that of a computational fluid dynamics (CFD) simulation. The F-Curves, which represents the cumulative time spent in the reactor 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, and suggest applying the methodology of tracer testing described in this work to investigate RTDs in OFRs and modify inlets, outlets, and use of internals prior to applications (e.g., field deployment vs. laboratory study).


2018 ◽  
Vol 25 (31) ◽  
pp. 31062-31070 ◽  
Author(s):  
Katheem Kiyasudeen ◽  
Mahamad Hakimi Ibrahim ◽  
Syahidah Akmal Muhammad ◽  
Sultan Ahmed Ismail ◽  
Fadzil Noor Gonawan ◽  
...  

2020 ◽  
Author(s):  
Andrew T. Lambe ◽  
Ezra C. Wood ◽  
Jordan E. Krechmer ◽  
Francesca Majluf ◽  
Leah R. Williams ◽  
...  

Abstract. Oxidation flow reactors (OFRs) are an emerging tool for studying the formation and oxidative aging of organic aerosols and other applications. The majority of OFR studies to date involved generation of the hydroxyl radical (OH) to mimic daytime oxidative aging processes. On the other hand, use of the nitrate radical (NO3) in modern OFRs to mimic nighttime oxidative aging processes has been limited due to the complexity of conventional techniques that are used to generate NO3. Here, we present a new method that uses a laminar flow reactor (LFR) to continuously generate dinitrogen pentoxide (N2O5) in the gas phase at room temperature from the NO2 + O3 and NO2 + NO3 reactions. The N2O5 is then injected into a dark Potential Aerosol Mass OFR and decomposes to generate NO3; hereafter, this method is referred to as OFR-iN2O5 (i = injected). To assess the applicability of the OFR-iN2O5 method towards different chemical systems, we present experimental and model characterization of the integrated NO3 exposure, NO3:O3, NO2:NO3, and NO2:O2 as a function of LFR and OFR conditions. These parameters were used to investigate the fate of representative organic peroxy radicals (RO2) and aromatic alkyl radicals generated from volatile organic compound (VOC) + NO3 reactions, and VOCs that are reactive towards both O3 and NO3. Finally, we demonstrate the OFR-iN2O5 method by generating and characterizing secondary organic aerosol from the β-pinene + NO3 reaction.


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