scholarly journals A computational fluid dynamics study of hydrogen bubbles in an electrochemical reactor

2005 ◽  
Vol 48 (spe) ◽  
pp. 219-229 ◽  
Author(s):  
Renata da Silva Cavalcanti ◽  
Severino Rodrigues de Farias Neto ◽  
Eudésio Oliveira Vilar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Electrode Surface ◽  
Electrochemical Reactor ◽  
Liquid System ◽  
Size Group ◽  
Group Model ◽  
Hydrodynamic Behavior ◽  
Hydrogen Bubbles ◽  
Reactor Hydrodynamics

Most electrochemical reactors present reactions with the growth and departure of gas bubbles which influence on the reactor hydrodynamics and this study is usually complex, representing a vast field for research. The present paper had as objective to study a bi-phase (gas-liquid) system aiming to foresee the influence of departure of hydrogen bubbles generated on effective electrode surface situated on cathodic semi-cell. Nevertheless, it was idealized that the gas was injected into the semi cell, through the effective electrode surface With this hypothesis, it was possible to study, and numerically analyze, the hydrodynamic behavior of the hydrogen bubbles in the interior of the study domain, applying concepts of computational fluid dynamics by using the computational applicative CFX-4 for the application of the MUSIG ("MUltiple-SIze-Group") model, taking into consideration the phenomena of coalescence and the distribution of the diameter of the bubbles.

Evaluation of the Effect of the Rotational Electrode Speed in an Electrochemical Reactor Using Computational Fluid Dynamics (CFD) Analysis

2011 ◽  
Vol 51 (17) ◽  
pp. 5947-5952 ◽  
Author(s):  
Helvio R. Mollinedo-Ponce-de-León ◽  
Sergio A. Martínez-Delgadillo ◽  
Víctor X. Mendoza-Escamilla ◽  
Claudia C. Gutiérrez-Torres ◽  
José A. Jiménez-Bernal
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Electrochemical Reactor ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd

Evaluating effective volume and hydrodynamic behavior in a full-scale ozone contactor with computational fluid dynamics simulation

2004 ◽  
Vol 4 (5-6) ◽  
pp. 277-288
Author(s):  
T. Mizuno ◽  
N.-S. Park ◽  
H. Tsuno ◽  
T. Hidaka
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mass Balance ◽  
Ozone Concentration ◽  
Cfd Simulation ◽  
Reaction Model ◽  
Dynamics Simulation ◽  
Effective Volume ◽  
Hydrodynamic Behavior ◽  
Ozone Contactor

An ozone reaction model combined with CFD (Computational Fluid Dynamics) technique was developed in this research. In the simulation of ozonation, hydrodynamic behavior caused by bubbling of ozone contacting-gas is important as well as reaction kinetics. CFD technique elucidated hydrodynamic behavior in the selected ozone contactor, which consisted of three main chambers. Back-mixing zone was found in each chamber. The higher velocities of water were observed in the second and third chambers than that in the first one. The flow of the opposite direction to the main flow was observed near the water surface. Based on the results of CFD simulation, each chamber was divided into small compartments, and hydrodynamic behavior and effective volume were discussed. Mass balance equations were also established in each compartment with reaction terms associated with DOC, odor compounds, bacteria, bromide ion and bromate ion. This reaction model was intended to predict dissolved ozone concentration, especially. We concluded that the model could predict favourably the mass balance of ozone, namely absorption efficiency of gaseous ozone, dissolved ozone concentration and ozone consumption. After establishing the model, we discussed the effects of hydrodynamic behavior on dissolved ozone concentration.

Separation efficiency of a hydrodynamic separator using a 3D computational fluid dynamics multiscale approach

2014 ◽  
Vol 69 (5) ◽  
pp. 1067-1073 ◽  
Author(s):  
Vivien Schmitt ◽  
Matthieu Dufresne ◽  
Jose Vazquez ◽  
Martin Fischer ◽  
Antoine Morin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Separation Efficiency ◽  
Perforated Plate ◽  
Global Model ◽  
Trapping Efficiency ◽  
Local Model ◽  
Multiscale Approach ◽  
Hydrodynamic Behavior ◽  
Particle Trajectories

The aim of this study is to investigate the use of computational fluid dynamics (CFD) to predict the solid separation efficiency of a hydrodynamic separator. The numerical difficulty concerns the discretization of the geometry to simulate both the global behavior and the local phenomena that occur near the screen. In this context, a CFD multiscale approach was used: a global model (at the scale of the device) is used to observe the hydrodynamic behavior within the device; a local model (portion of the screen) is used to determine the local phenomena that occur near the screen. The Eulerian–Lagrangian approach was used to model the particle trajectories in both models. The global model shows the influence of the particles' characteristics on the trapping efficiency. A high density favors the sedimentation. In contrast, particles with small densities (1,040 kg/m3) are steered by the hydrodynamic behavior and can potentially be trapped by the separator. The use of the local model allows us to observe the particle trajectories near the screen. A comparison between two types of screens (perforated plate vs expanded metal) highlights the turbulent effects created by the shape of the screen.

Application of Computational Fluid Dynamics to Multiphase Flow in Bubble Columns

2002 ◽  
Vol 1 (1) ◽  
Author(s):  
Francesco Bertola ◽  
Marco Vanni ◽  
Giancarlo Baldi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Bubbly Flow ◽  
Liquid System ◽  
Bubble Columns ◽  
Bubble Plume ◽  
Computational Fluid Dynamics Cfd ◽  
2D And 3D ◽  
Two Fluid ◽  
Present Ability

The application of Computational Fluid Dynamics (CFD) to the simulation of bubble columns devices is discussed. A comparison between different modeling approaches has been carried out in order to understand which is the present ability of CFD codes to predict the flow in a gas–liquid system. The effect of different options of simulation, such as 2D and 3D grids with different density of cells, order of discretization, turbulence closure, has been studied for systems characterized by different values of gas hold-up. The analysis is restricted to bubbly flow conditions. Eulerian-Eulerian two fluid models have been used to describe both the time–dependent motion of the bubble plume and the time-averaged flow pattern in the column. The systems considered are those experimentally characterized by the group of Eigenberger (Becker et al., 1994), by Mudde et al. (1997), by the group of Dudukovic (Sanyal et al., 1999) and by Ho Yu and Kim (1991).

scholarly journals Geometry and head loss in Venturi injectors through computational fluid dynamics

2016 ◽  
Vol 36 (3) ◽  
pp. 482-491 ◽  
Author(s):  
Juan Manzano ◽  
Carmen V. Palau ◽  
M. de Azevedo Benito ◽  
V. do Bomfim Guilherme ◽  
Denise V. Vasconcelos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Head Loss ◽  
Sharp Edge ◽  
Nozzle Throat ◽  
Hydrodynamic Behavior ◽  
Head Losses ◽  
Lower Head ◽  
Diffuser Angle ◽  
The Relationship

ABSTRACT To determine the influence of geometry on the hydrodynamic behavior of Venturi injectors, using computational fluid dynamics techniques, we studied, at the Universitat Politècnica de València, Valencia, Spain, the geometric parameters that exert the most influence on head losses: the relationship between throat diameter and nozzle (β), nozzle angle (α1) and diffuser angle (α2). In addition, three throat morphologies (B1: nozzle-throat and throat-diffuser with a sharp edge; B2: nozzle-diffuser with a zero-length, sharp-edge throat; B3: nozzle-throat and throat-diffuser with rounded edge). We analyzed their influence on the velocity distribution and differential pressure between inlet and throat (DP/γ), throat and outlet (Δhv/γ), and outlet and throat ((P3-P2)/γ). The development of the velocity profile from the throat is slower the greater β is and the lower α2 is. DP/γ decreases with β, increases with α1 and varies little with α2. Δhv/γ decreases with β and increases with α1 and α2. (P3-P2)/γ decreases with β and increases with α1 and α2. Geometry B3 decreases the losses and delays the onset of cavitation. Thus, the lower β and the higher α2, the greater the losses; however, the influence of α1 is less clear. The rounded edges produce lower head losses.

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