Hydrodynamics and Mass Transfer Simulation in Airlift Bioreactor with Settler using Computational Fluid Dynamics

2017 ◽  
Vol 15 (4) ◽  
Author(s):  
Oscar M. Hernández-Calderón ◽  
Marcos D. González-Llanes ◽  
Erika Y. Rios-Iribe ◽  
Sergio A. Jiménez-Lam ◽  
Ma.del Carmen Chavez-Parga ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Mass Transfer ◽  
Computational Fluid Dynamics ◽  
Liquid Velocity ◽  
Fluid Dynamic ◽  
Gas Holdup ◽  
Airlift Bioreactor ◽  
Cfd Modeling ◽  
Two Phase

Abstract In this work, the effect of inlet-gas superficial velocity over the circulation liquid velocity, gas holdup and mass transfer, from an airlift bioreactor with settler were studied by Computational Fluid Dynamics (CFD) modeling and contrasted with experimental results. Multiphase mixture model and κ-ε turbulence model were used to describe the two phases gas-liquid flow pattern in airlift bioreactor. The hydrodynamic parameters such as liquid circulation velocity and gas holdup were computed by solving the governing equations of continuity, moment and turbulence transport using the finite volume method. Global mass transfer coefficient was evaluated through the Higbie’s penetration theory and the two-phase fluid dynamic theory. Comparison between our numerical data and experimental data previously reported in the literature was done. Numerical and experimental data were very close, and the differences found were discussed in terms of the limitations of this study.

Computational Fluid Dynamics Modeling of Gas–Liquid Cylindrical Cyclones, Geometrical Analysis

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Juan Carlos Berrio ◽  
Eduardo Pereyra ◽  
Nicolas Ratkovich
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Cfd Modeling ◽  
Nozzle Geometry ◽  
Geometrical Parameters ◽  
Experimental Setup ◽  
Dynamics Modeling ◽  
Two Phase ◽  
Mean Square Errors

The gas–liquid cylindrical cyclone (GLCC) is a widely used alternative for gas–liquid conventional separation. Besides its maturity, the effect of some geometrical parameters over its performance is not fully understood. The main objective of this study is to use computational fluid dynamics (CFD) modeling in order to evaluate the effect of geometrical modifications in the reduction of liquid carry over (LCO) and gas carry under (GCU). Simulations for two-phase flow were carried out under zero net liquid flow, and the average liquid holdup was compared with Kanshio (Kanshio, S., 2015, “Multiphase Flow in Pipe Cyclonic Separator,” Ph.D. thesis, Cranfield University, Cranfield, UK) obtaining root-mean-square errors around 13% between CFD and experimental data. An experimental setup, in which LCO data were acquired, was built in order to validate a CFD model that includes both phases entering to the GLCC. An average discrepancy below 6% was obtained by comparing simulations with experimental data. Once the model was validated, five geometrical variables were tested with CFD. The considered variables correspond to the inlet configuration (location and inclination angle), the effect of dual inlet, and nozzle geometry (diameter and area reduction). Based on the results, the best configuration corresponds to an angle of 27 deg, inlet location 10 cm above the center, a dual inlet with 20 cm of spacing between both legs, a nozzle of 3.5 cm of diameter, and a volute inlet of 15% of pipe area. The combination of these options in the same geometry reduced LCO by 98% with respect to the original case of the experimental setup. Finally, the swirling decay was studied with CFD showing that liquid has a greater impact than the gas flowrate.

CFD Modelling of Multiphase Flows: An Overview

2003 ◽  
Author(s):  
Rajnish K. Calay ◽  
Arne E. Holdo
Keyword(s):  
Fluid Dynamics ◽  
Mass Transfer ◽  
Computational Fluid Dynamics ◽  
Numerical Modeling ◽  
Mathematical Models ◽  
Cfd Modelling ◽  
Two Phase ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd ◽  
Numerical Modeling Of Flows

The Computational Fluid Dynamics (CFD) is now increasingly being used for modeling industrial flows, i.e. flows which are multiphase and turbulent. Numerical modeling of flows where momentum, heat and mass transfer occurs at the interface presents various difficulties due to the wide range of mechanisms and flow scenarios present. This paper attempts to provide a summary of available mathematical models and techniques for two-phase flows. Some comments are also made on the models available in the commercially available codes.

Computational Fluid Dynamics Modeling of Flow Boiling in Microchannels With Nonuniform Heat Flux

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Daniel Lorenzini ◽  
Yogendra K. Joshi
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Phase Change ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Cfd Modeling ◽  
Temperature Phase ◽  
Phase Flow ◽  
Two Phase

The computational fluid dynamics (CFD) modeling of boiling phenomena has remained a challenge due to numerical limitations for accurately simulating the two-phase flow and phase-change processes. In the present investigation, a CFD approach for such analysis is described using a three-dimensional (3D) volume of fluid (VOF) model coupled with a phase-change model accounting for the interfacial mass and energy transfer. This type of modeling allows the transient analysis of flow boiling mechanisms, while providing the ability to visualize in detail temperature, phase, and pressure distributions for microscale applications with affordable computational resources. Results for a plain microchannel are validated against benchmark correlations for heat transfer (HT) coefficients and pressure drop as a function of the heat flux and mass flux. Furthermore, the model is used for the assessment of two-phase cooling in microelectronics under a realistic scenario with nonuniform heat fluxes at localized regions of a silicon microchannel, relevant to the cooling layer of 3D integrated circuit (IC) architectures. Results indicate the strong effect of two-phase flow regime evolution and vapor accumulation on HT. The effects of reduced saturation pressure, subcooling, and flow arrangement are explored in order to provide insight about the underlying physics and cooling performance.

scholarly journals Computational Fluid Dynamics Simulations of Gas-liquid Two-phase Flow Characteristics through a Vertical to Horizontal Right Angled Elbow

2017 ◽  
Vol 30 (1&2) ◽  
pp. 1-16 ◽  
Author(s):  
N. Z. Aung ◽  
T. Yuwono
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Phase ◽  
Test Section ◽  
Two Phase Flow ◽  
Liquid Velocity ◽  
Phase Flow ◽  
Cfd Simulations ◽  
Two Phase ◽  
Horizontal Pipe

Having a clear understanding on the phase distribution of gas-liquid two-phase flow through elbow bends is vital in mixing and separation system designs. This paper presents the computational fluid dynamics (CFD) simulations and experimental observations of gas-liquid two-phase flow pattern characteristic through a vertical to horizontal right angled (90°) elbow. Experimental observations were conducted in a transparent test section that consisted of a vertical pipe, elbow bend and horizontal pipe with an inside diameter of 0.036 m. The CFD simulations were performed by using a computer software package, FLUENT 6.2. Bubbly flow conditions were created in the vertical test section with the variation of superficial liquid Reynolds number from 13 497 to 49 488 and volumetric gas quality from 0.05 to 0.2. The CFD results showed a good agreement with experimental results in the following observations. The results showed that gas-liquid flow pattern inside and downstream of the elbow bend mainly depended on liquid velocity and it is also influenced by gas quality at high liquid velocities. At lower liquid velocities, gas-liquid separation began early in the elbow bend and gas-phase migrated to outer bend. Then, it smoothly transformed to stratified flow at elbow outlet. When the liquid velocity was further increased, the liquid phase occupied the outer bend rubbing the gas phase to the inner bend and delayed the formation of gas layer in the horizontal pipe. The increase of gas quality in higher liquid velocities promoted gas core formation at the elbow exit and caused wavy gas layers at the downstream of the elbow.

Analysis and Modeling of Liquid Holdup in Low Liquid Loading Two-Phase Flow Using Computational Fluid Dynamics and Experimental Data

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Miguel Ballesteros ◽  
Nicolás Ratkovich ◽  
Eduardo Pereyra
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Oil And Gas ◽  
Operating Conditions ◽  
Liquid Holdup ◽  
Liquid Loading ◽  
Two Phase ◽  
Acceptable Error ◽  
Pharmaceutical Industries

Abstract Low liquid loading flow occurs very commonly in the transport of any kind of wet gas, such as in the oil and gas, the food, and the pharmaceutical industries. However, most studies that analyze this type of flow do not cover actual industry fluids and operating conditions. This study focused then on modeling this type of flow in medium-sized (6-in [DN 150] and 10-in [DN 250]) pipes, using computational fluid dynamics (CFD) simulations. When comparing with experimental data from the University of Tulsa, the differences observed between experimental and CFD data for the liquid holdup and the pressure drop seemed to fall within acceptable error, around 20%. Additionally, different pipe sections from a Colombian gas pipeline were simulated with a natural gas-condensate mixture to analyze the effect of pipe inclination and operation variables on liquid holdup, in real industry conditions. It was noticed that downward pipe inclinations favored smooth stratified flow and decreased liquid holdup in an almost linear fashion, while upward inclinations generated unsteady wavy flows, or even a possible annular flow, and increased liquid holdup and liquid entrainment into the gas phase.

Comparison of Particle-Wall Interaction Boundary Conditions in the Prediction of Cyclone Collection Efficiency in Computational Fluid Dynamics (CFD) Modeling

2010 ◽  
Vol 660-661 ◽  
pp. 158-163
Author(s):  
M.Ramirez Valverde ◽  
José Renato Coury ◽  
José Antônio Silveira Gonçalves
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Collection Efficiency ◽  
Cfd Modeling ◽  
Wall Boundary Conditions ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Interaction

In recent years, many computational fluid dynamics (CFD) studies have appeared attempting to predict cyclone pressure drop and collection efficiency. While these studies have been able to predict pressure drop well, they have been only moderately successful in predicting collection efficiency. Part of the reason for this failure has been attributed to the relatively simple wall boundary conditions implemented in the commercially available CFD software, which are not capable of accurately describing the complex particle-wall interaction present in a cyclone. According, researches have proposed a number of different boundary conditions in order to improve the model performance. This work implemented the critical velocity boundary condition through a user defined function (UDF) in the Fluent software and compared its predictions both with experimental data and with the predictions obtained when using Fluent’s built-in boundary conditions. Experimental data was obtained from eight laboratory scale cyclones with varying geometric ratios. The CFD simulations were made using the software Fluent 6.3.26.

A Renewed CFD Model for Prediction of Gas-Solid Flow in Downer Reactors

2004 ◽  
Author(s):  
Karolline Ropelato ◽  
Henry F. Meier ◽  
Marco A. Cremasco
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Solid Phase ◽  
Fluid Dynamic ◽  
Space Time ◽  
Good Representation ◽  
Flow Reactors ◽  
Steady State Condition ◽  
Solid Flow

This work provides a renewed space-time muitiphase model known as “insviscid model”, according to terminology of the multiphase flows theory, where the gas-solid modeling presents some special characteristics such as: unsteady and 3D flow for two fluid on an Eulerian-Eulerian appoach; dissipation of turbulent kinetic energy only on the gas as real fluid; and with assumption of solid phase behaves like some kind of hypothetical fluid without shear stress from molecular causes. By using Computational Fluid Dynamics Techniques (CFD), it was carried out the development of the model with studies of Verification and Validation in Computational Fluid Dynamics (V&V in CFD), in order to predict the main fluid dynamic features of down flow reactors of petroleum industry. Despite the simplified modeling, the renewed gas-solid model has shown a good representation of the main phenomenological characteristics of the turbulent gas-solid flow. Numerically, the model does not present difficulties for convergence with traditional finite volume methods with collocated grids and body fitted arrangement of the control volumes. The model considers, as initial condition for space-time integration, the flow of the single phase (gas) to guarantee stability and to achieve the steady state condition. Experimental data obtained in the literature, Cheng et al. [1], were used for model validation, and three others cases for verification of the fluid dynamics effects from different gas-solid inlet condition. By comparison between the model predictions with experimental data, it is possible to conclude there is a good agreement. CFD techniques proved to be also a powerful tool to predict the fluid dynamic of inlet changing of the down flow reactors, and it can be used with success in chemical process optimization.

scholarly journals Using computational fluid dynamics to describe H2S mass transfer across the water–air interface in sewers

2019 ◽  
Vol 79 (10) ◽  
pp. 1934-1946 ◽  
Author(s):  
Katharina Teuber ◽  
Tabea Broecker ◽  
Thomas Ruby Bentzen ◽  
Dietmar Stephan ◽  
Gunnar Nützmann ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Mass Transfer ◽  
Computational Fluid Dynamics ◽  
Ph Value ◽  
Three Dimensional ◽  
Test Case ◽  
Two Phase ◽  
The Past ◽  
Time Flow ◽  
Flow Velocities

Abstract For the past 70 years, researchers have dealt with the investigation of odour in sewer systems caused by hydrogen sulphide formations and the development of approaches to describe it. The state-of-the-art models are one-dimensional. At the same time, flow and transport phenomena in sewers can be three-dimensional, for example the air flow velocities in circular pipes or flow velocities of water and air in the reach of drop structures. Within the past years, increasing computational capabilities enabled the development of more complex models. This paper uses a three-dimensional two-phase computational fluid dynamics model to describe mass transfer phenomena between the two phases: water and air. The solver has been extended to be capable of accounting account for temperature dependency, the influence of pH value and a conversion to describe simulated air phase concentrations as partial pressure. Its capabilities are being explored in different application examples and its advantages compared to existing models are demonstrated in a highly complex three-dimensional test case. The resulting interH2SFoam solver is a significant step in the direction of describing and analysing H2S emissions in sewers.

scholarly journals Modeling of H2 Permeation through Electroless Pore-Plated Composite Pd Membranes Using Computational Fluid Dynamics

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 123
Author(s):  
Alberto Fernández ◽  
Cintia Casado ◽  
David Alique ◽  
José Antonio Calles ◽  
Javier Marugán
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Hydrogen Permeation ◽  
Membrane Surface ◽  
Molar Fraction ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Wide Range ◽  
The Impact

This work focused on the computational fluid dynamics (CFD) modeling of H2/N2 separation in a membrane permeator module containing a supported dense Pd-based membrane that was prepared using electroless pore-plating (ELP-PP). An easy-to-implement model was developed based on a source–sink pair formulation of the species transport and continuity equations. The model also included the Darcy–Forcheimer formulation for modeling the porous stainless steel (PSS) membrane support and Sieverts’ law for computing the H2 permeation flow through the dense palladium film. Two different reactor configurations were studied, which involved varying the hydrogen flow permeation direction (in–out or out–in). A wide range of experimental data was simulated by considering the impact of the operating conditions on the H2 separation, such as the feed pressure and the H2 concentration in the inlet stream. Simulations of the membrane permeator device showed an excellent agreement between the predicted and experimental data (measured as permeate and retentate flows and H2 separation). Molar fraction profiles inside the permeator device for both configurations showed that concentration polarization near the membrane surface was not a limit for the hydrogen permeation but could be useful information for membrane reactor design, as it showed the optimal length of the reactor.

scholarly journals Flow Characteristics of Multiphase Glass Beads-Water Slurry through Horizontal Pipeline using Computational Fluid Dynamics

2019 ◽  
Vol 16 (2) ◽  
pp. 6605-6623 ◽  
Author(s):  
Shofique Uddin Ahmed ◽  
Rajesh Arora ◽  
Om Parkash
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Control Volume ◽  
Particle Diameter ◽  
Solid Particles ◽  
Slurry Flow ◽  
Two Phase ◽  
Horizontal Pipe

Over the decades conveying solid particles through pipelines is a prevalent usage for many industries like food industries, pharmaceutical, oil and gas-solid handling, power generations etc. In the present study, slurry flow through 54.9 mm diameter and 4 m long horizontal pipe with solid particle diameter 0.125 mm and specific gravity 2.47 has been numerically analysed using a granular version of Eulerian two-phase model and RNG K-  model. The solid particles are considered as mono-dispersed in the Eulerian model. These models are available in computational fluid dynamics (CFD) fluent software package. Non-uniform structured three-dimensional mesh with a refinement near wall boundary region has been selected for discretising the flow domain, and governing equations are solved using control volume finite difference method. Simulations are conducted at velocity varying from 1 m/s to 5 m/s and efflux concentration varying from 0.1 to 0.5 by volume. Different slurry flow parameters such as solid concentration distribution, velocity distribution, pressure drop etc. have been analysed from the simulated results. The simulated results of pressure drop are correlated with the experimental data available in previous literature and are found to be in excellent compliance with the experimental data.

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