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).

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).

Residence time and contact volume in sloped compost and compost/vegetated filter beds

2011 ◽  
Vol 63 (6) ◽  
pp. 1093-1098
Author(s):  
K. Coulson ◽  
R. J. Petrell ◽  
D. Chiu
Keyword(s):  
Residence Time ◽  
Flow Rate ◽  
Pore Space ◽  
Plug Flow ◽  
Concentration Data ◽  
Filter Width ◽  
In Series ◽  
Free Drainage ◽  
Bed Slope ◽  
The Ideal

Little is known about transport mechanisms in sloped dormant vegetated and compost only filters for roadway runoff. Residence time experiments were carried out in triplicate in 0.254 m wide × 0.65 m long by 0.10 m deep beds using a bromide tracer. Bed slope was 12°. Only at the lowest flow rate tested (0.276 l/min per m of filter width) were mean residence times in compost beds with and without dormant grasses different. Pools formed ahead of beds at higher flow rate, and pool depth reached bed depth at 3.54 l/min/m. The ideal model of a well-mixed pool in series with a plug flow porous bed was a good predictor of effluent concentration data at flows ≥2.66 l/min/m. Theoretical contact volume within the beds increased with flow rate to reach approx. 30% of available pore space, while free drainage volume declined. Data shows that designs for sloped compost filter beds must consider flow, bed depth and length, and whether or not areas for pooling are needed.

scholarly journals Simulating Trambouze reaction for a series reactor

2020 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Amizon Azizan ◽  
Nornizar Anuar
Keyword(s):  
Flow Rate ◽  
Coming Out ◽  
Flow Reactor ◽  
Plug Flow ◽  
Volumetric Flow Rate ◽  
Continuous Stirred Tank Reactor ◽  
Maximum Conversion ◽  
Outlet Stream ◽  
Continuous Stirred Tank ◽  
Flow Rate Influence

Simulating the existing data on Trambouze reaction is compiled in this article. The objective of the work is to present the change of volumetric flow rate and the inlet concentration of key reactant A in a series continuous stirred tank reactor-plug flow reactor (CSTR-PFR) configurations. The volumetric flow rate does not affect selectivity and conversion for a constant volumetric flow rate operating condition, entering CSTR and PFR, at a specific concentration of reactant. The CSTR-PFR series reactor configuration is proposed for the aim of maximizing the selectivity of the desired product B in comparison to the undesired products X and Y. CSTR as the first reactor is capable to achieve the maximum conversion at the highest selectivity of A. PFR is then proposed after CSTR in a configuration of CSTR-PFR, to allow higher conversion value to be achieved for the resulted outlet stream conditions coming out of the first reactor, CSTR. Both reactors commonly encounter a decrease in the initial concentration of A and an increase to the formation of other products. The CSTR entering volumetric flow rate influence the volume sizes needed in achieving the maximum selectivity and conversion

High-performance aerosol sampler with liquid phase recirculation and pre-concentration of particles

2018 ◽  
pp. 25-31
Author(s):  
A. E. Akmalov ◽  
G. E. Kotkovskii ◽  
S. V. Stolyarov ◽  
B. I. Verdiev ◽  
R. S. Ovchinnikov ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Flow Rate ◽  
High Performance ◽  
Collection Efficiency ◽  
Volumetric Flow Rate ◽  
Flow Rates ◽  
Particle Collection ◽  
Aerosol Mass ◽  
Biogenic Aerosols ◽  
Short Time

Testing the surrounding environment for the presence of biogenic aerosols is crucial in ensuring its safety for the population. It is often necessary to collect aerosol samples from large areas in short time, which demands excellent particle collection efficiency, a sufficient incoming air flow rate and a capacity to maintain the viability of the collected samples. Below we present the aerosol sampler with a high volumetric flow rate based on a two-stage particle concentration algorithm and consisting of a virtual impactor and a cyclone concentrator with a recirculating liquid phase. We provide all necessary calculations and an algorithm for modeling impactor parameters. The sampler was tested using dry and liquid formulations dispersed into the particles of 0.5 to 5 μm in diameter. We demonstrate that at volumetric flow rates over 4,000 l/min efficiency of particle collection into the liquid phase at a volume of 10 ml makes over 20% of the total aerosol mass and at volumetric flow rates over 300 l/min this value is over 60%. The proposed device maintains viability of the collected microorganisms. The sampler is portable, with flexible settings for sampling and cleaning, and can be controlled remotely over the network.

scholarly journals Optimization of injected radiotracer volume for flow rate measurement in closed conduits

2020 ◽  
Vol 74 (5) ◽  
pp. 305-312
Author(s):  
Miroslav Pavlovic ◽  
Marijana Pantovic-Pavlovic ◽  
Pavel Bartl ◽  
Jasmina Stevanovic ◽  
Bojan Radak
Keyword(s):  
Flow Rate ◽  
Fluid Velocity ◽  
Plug Flow ◽  
Volumetric Flow Rate ◽  
Pilot Scale ◽  
Quality Performance ◽  
Flow Meters ◽  
Injection Volume ◽  
In Situ Calibration ◽  
Flow Quality

In chemical processes it is essential that the flow in the process is accurately defined. Fluid velocity measurements are important for fluid flow quality performance in flow systems. This study focuses on determination of the volumetric flow rate and its standard (relative) deviation for calibration of conventional flow meters by using a radiotracer approach. The measurements for flow meter calibration were performed at a pilot-scale flow rig using Technetium-99 m (99mTc) as a radiotracer in the form of pertechnetate ion (99mTcO4-). The measured data were analyzed, and precision of the experimental setup was investigated under two different approaches ? IAEA?s RTD software and sum approximation of raw data. For the first time, the variation of standard deviation of calculated flow rate with the injection volume and activity of the radiotracer was determined. Plug flow with axial dispersion was used to simulate the measured RTD curves and investigate the flow dynamics of the flowing water. The results of the study have shown the possibility of in situ calibration of flow meters with a relative error lower than 1 %. They also revealed a slight dependency of the precision of output results on the injection volume as well as similar results for manual and specialized RTD software data processing.

scholarly journals Numerical and experimental study of flow distribution in tubular space of fin-and-tube heat exchanger with modified inlet manifold

2018 ◽  
Vol 240 ◽  
pp. 02010
Author(s):  
Tomasz Stelmach
Keyword(s):  
Heat Exchanger ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Tube Bundle ◽  
Cross Flow ◽  
Flow Distribution ◽  
Volumetric Flow Rate ◽  
Tube Heat Exchanger ◽  
Experimental Stand ◽  
Inlet Manifold

This paper presents the experimental and numerical investigation of flow distribution in the tubular space of cross-flow fin-and-tube heat exchanger. The tube bundle with two rows arranged in staggered formation is considered. A modified heat exchanged manifold, with inlet nozzle pipe located asymmetrically is considered. The outlet nozzle pipe is located in the middle of the outlet manifold, with a standard shape. An experimental stand allows one to investigate the volumetric flow rate in heat exchanger tubular space using the ultrasonic flowmeters. Various inlet mass flow rate i.e. 3 m3/h, 4 m3/h and 5 m3/h are considered. The experimental results are compared with CFD simulation performed in ANSYS CFX program using the SSG Reynolds Stress turbulence model. A relatively good agreement is found for tube Re numbers varied from 1800 to 3100.

Cooling Fan Model for Thermal Design of Compact Electronic Equipment: Improvement of Modeling Using PQ Curve

2009 ◽  
Author(s):  
Hajime Nakamura
Keyword(s):  
Flow Rate ◽  
Cfd Simulation ◽  
Axial Flow ◽  
Volumetric Flow Rate ◽  
Thermal Design ◽  
System Effect ◽  
Simple Method ◽  
Cooling Fans ◽  
The Difference ◽  
The Impact

In order to hasten the thermal design for forced convection electronic devices, cooling fans should be modeled to reduce a computational load. A fan-curve-model, which generates volumetric flow rate versus the characteristics pressure difference of a fan, is very simple and usually incorporated into commercial CFD codes. However, this model often results in an erroneous flow rate. In this work, both the experiments and the CFD simulation were performed around small axial-flow-fans of 30 and 40 mm in diameter. The measured PQ curve was applied to the fan model, and compared the result of the simulation to the experimental data. It was clarified that the major reason behind the disagreement was the difference in the pressure definition of the fan model from the PQ curve measured using a chamber. Based on this, a simple method was proposed to correct this definition. Also, the system effect, which is the impact of obstacles on the fan delivery curve, was investigated by setting a cylindrical obstacle at upstream or downstream proximity of the fan.

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