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

2017 ◽  
Author(s):  
Dhruv Mitroo ◽  
Yujian Sun ◽  
Daniel P. Combest ◽  
Purushottam Kumar ◽  
Brent J. Williams
Keyword(s):  
Cfd Simulation ◽  
Plug Flow ◽  
Flow Patterns ◽  
Space Time ◽  
Flow Reactors ◽  
Tracer Testing ◽  
Aerosol Mass ◽  
In Series ◽  
Field Deployment ◽  
Volumetric Flowrate

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).

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

2018 ◽  
Vol 11 (3) ◽  
pp. 1741-1756 ◽  
Author(s):  
Dhruv Mitroo ◽  
Yujian Sun ◽  
Daniel P. Combest ◽  
Purushottam Kumar ◽  
Brent J. Williams
Keyword(s):  
Flow Rate ◽  
Cfd Simulation ◽  
Plug Flow ◽  
Volumetric Flow Rate ◽  
Flow Patterns ◽  
Space Time ◽  
Flow Reactors ◽  
Tracer Testing ◽  
Aerosol Mass ◽  
In Series

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).

Modeling of Vortex-Flow Solar Reactor via Ideal Reactors in Series Approach

2010 ◽  
Author(s):  
Nesrin Ozalp ◽  
Vidyasagar Shilapuram ◽  
D. Jayakrishna
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Vortex Flow ◽  
Flow Reactor ◽  
Flow Behavior ◽  
Plug Flow ◽  
Flow Reactors ◽  
In Series ◽  
Sweeping Gas

In this work, we present a thorough reaction engineering analysis on the modeling of a vortex-flow reactor to show that commonly practiced one-plug reactor approach is not sufficient to explain the flow behavior inside the reactor. Our study shows that N-plug flow reactors in series is the best approach in predicting the flow dynamics based on the computational fluid dynamics (CFD) simulations. We have studied the residence time distribution using CFD by two different methods. The residence time distribution characteristics are calculated by approximating the real reactor as N-ideal reactors in series, and then estimated the number of ideal reactors in series for the model. We have validated our CFD model by comparing the simulation results with experimental results. Finally, we have done a parametric study with a different sweeping gas to identify the best screening gas to avoid carbon deposition inside the vortex-flow reactor. Our results have shown that hydrogen is a better screening gas than argon.

PIV Validation of Blood-heart Valve Leaflet Interaction Modelling

2007 ◽  
Vol 30 (7) ◽  
pp. 640-648 ◽  
Author(s):  
R. Kaminsky ◽  
K. Dumont ◽  
H. Weber ◽  
M. Schroll ◽  
P. Verdonck
Keyword(s):  
Shear Stress ◽  
Heart Valve ◽  
Cfd Simulation ◽  
Flow Simulation ◽  
Data Sets ◽  
Arbitrary Lagrangian Eulerian ◽  
Velocity Magnitude ◽  
Image Velocimetry ◽  
Interaction Modelling ◽  
In Series

The aim of this study was to validate the 2D computational fluid dynamics (CFD) results of a moving heart valve based on a fluid-structure interaction (FSI) algorithm with experimental measurements. Firstly, a pulsatile laminar flow through a monoleaflet valve model with a stiff leaflet was visualized by means of Particle Image Velocimetry (PIV). The inflow data sets were applied to a CFD simulation including blood-leaflet interaction. The measurement section with a fixed leaflet was enclosed into a standard mock loop in series with a Harvard Apparatus Pulsatile Blood Pump, a compliance chamber and a reservoir. Standard 2D PIV measurements were made at a frequency of 60 bpm. Average velocity magnitude results of 36 phase-locked measurements were evaluated at every 10° of the pump cycle. For the CFD flow simulation, a commercially available package from Fluent Inc. was used in combination with in-house developed FSI code based on the Arbitrary Lagrangian-Eulerian (ALE) method. Then the CFD code was applied to the leaflet to quantify the shear stress on it. Generally, the CFD results are in agreement with the PIV evaluated data in major flow regions, thereby validating the FSI simulation of a monoleaflet valve with a flexible leaflet. The applicability of the new CFD code for quantifying the shear stress on a flexible leaflet is thus demonstrated. (Int J Artif Organs 2007; 30: 640–8)

Earthworms as plug flow reactors: a first-order kinetic study on the gut of the vermicomposting earthworm Eudrilus eugeniae

2018 ◽  
Vol 25 (31) ◽  
pp. 31062-31070 ◽  
Author(s):  
Katheem Kiyasudeen ◽  
Mahamad Hakimi Ibrahim ◽  
Syahidah Akmal Muhammad ◽  
Sultan Ahmed Ismail ◽  
Fadzil Noor Gonawan ◽  
...  
Keyword(s):  
Kinetic Study ◽  
Plug Flow ◽  
Order Kinetic ◽  
Eudrilus Eugeniae ◽  
Flow Reactors ◽  
First Order

scholarly journals Nitrate radical generation via continuous generation of dinitrogen pentoxide in a laminar flow reactor coupled to an oxidation flow reactor

2020 ◽  
Author(s):  
Andrew T. Lambe ◽  
Ezra C. Wood ◽  
Jordan E. Krechmer ◽  
Francesca Majluf ◽  
Leah R. Williams ◽  
...  
Keyword(s):  
Laminar Flow ◽  
Flow Reactor ◽  
Nitrate Radical ◽  
Peroxy Radicals ◽  
Flow Reactors ◽  
Dinitrogen Pentoxide ◽  
Oxidative Aging ◽  
Chemical Systems ◽  
Alkyl Radicals ◽  
Aerosol Mass

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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