scholarly journals Study of the Pressure Drop and Flow Field in Standard Gas Cyclone Models Using the Granular Model

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Nabil Kharoua ◽  
Lyes Khezzar ◽  
Zoubir Nemouchi
Keyword(s):  
Pressure Drop ◽  
High Temperatures ◽  
Turbulence Models ◽  
Conical Part ◽  
The Core ◽  
Simplifying Assumptions ◽  
Vortex Finder ◽  
Computational Fluid Dynamics Cfd ◽  
Rsm Model ◽  
Particle Laden Flow

A particle-laden flow inside solid gas cyclones has been studied using computational fluid dynamics (CFD). The effects of high temperatures and different particle loadings have been investigated. The Reynolds stress (RSM) model-predicted results, in the case of pure gas, are within engineering accuracy even at high temperatures. Using the granular mixture model for the cases of particle-laden flow, discrepancies occurred at relatively high loadings (up to 0.5 kg/m3). Since the pressure drop is strongly related to the friction inside the cyclone body, the concept of entropy generation has been employed to detect regions of high frictional effects. Friction has been observed to be important at the vortex finder wall, the bottom of the conical-part wall, and the interface separating the outer and the core streams. The discrepancies between the present numerical simulation and the experimental results taken from the existing literature, which are caused by the mixture and turbulence models simplifying assumptions, are discussed in this paper.

CFD Prediction of Pressure Drop and Flow Field in Standard Gas Cyclone Models

2009 ◽  
Author(s):  
Nabil Kharoua ◽  
Lyes Khezzar ◽  
Zoubir Nemouchi
Keyword(s):  
Pressure Drop ◽  
Conical Part ◽  
The Core ◽  
Cfd Models ◽  
Different Temperatures ◽  
Simplifying Assumptions ◽  
Vortex Finder ◽  
Computational Fluid Dynamics Cfd ◽  
Particle Laden Flow ◽  
Standard Gas

Pressure drop is an important performance parameter for cyclone separators. A computational fluid dynamics (CFD) study of the pressure drop in cyclones using the Reynolds stress (RSM) and the granular mixture models is presented in this paper. The study includes three different cases; pure gas at ambient temperature, pure gas at different temperatures, and particle-laden flow. The first two cases were reasonably well predicted while the presence of particles with a relatively high loading (up to 1 kg/m3 of fluid) caused some discrepancies in the predicted results. The concept of entropy generation, used in this work, has permitted to detect regions of high frictional effect in the vortex finder, the bottom of the conical part, and at the interface separating the outer and the core streams. The simplifying assumptions employed in the CFD models and some numerical details are discussed.

CFD Prediction of Gas-Liquid Separation Efficiency of Geothermal Steam-Water Cyclone Separator Using a Verified Turbulence Model

2017 ◽  
Author(s):  
Xidong Hu ◽  
Shaoxiang Qian ◽  
Kaori Yamauchi ◽  
Haruo Okochi
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Velocity Distribution ◽  
Flow Velocity ◽  
Separation Efficiency ◽  
Turbulence Models ◽  
Phase Flow ◽  
Cyclone Separator ◽  
Steam Quality ◽  
Rsm Model

The present paper aims to predict the separation efficiency and pressure drop of a vertical geothermal cyclone type separator using CFD (Computational Fluid Dynamics) simulations, for optimizing the design of such separator. A benchmark study was firstly performed for a single phase flow in a Stairmand design cyclone using four different turbulence models, in order to verify the prediction accuracy of flow velocity distribution by comparison with experimental data in literature. The investigated turbulence models include (1) Renormalization Group (RNG) k-ε, (2) Realizable k-ε, (3) Reynolds stress turbulence model (RSM) and (4) Large eddy simulation (LES). Results show that RNG k-ε and Realizable k-ε models are not capable of reproducing the experimental data while the RSM and LES models reproduce the flow velocity distribution very well. Then, CFD simulations of two-phase flow in a steam-water cyclone separator were carried out for different stream inlet velocities applying the RSM model. This is based on the consideration that steady state analysis can be done for the RSM model, and however, transient analysis is needed for the LES model, and hence, more expensive and time-consuming for engineering applications. The CFD results for outlet steam quality and pressure drop were obtained under different stream inlet velocities. The separation efficiency and outlet steam quality decreases a little when the inlet velocity increases from 34.5m/s to 72m/s. However, the outlet steam quality predicted in the present CFD analysis is close to that of Lazalde-Crabtree.

scholarly journals CFD Modeling of Hydrocyclones—A Study of Efficiency of Hydrodynamic Reservoirs

Fluids ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 118 ◽  
Author(s):  
Marvin Durango-Cogollo ◽  
Jose Garcia-Bravo ◽  
Brittany Newell ◽  
Andres Gonzalez-Mancera
Keyword(s):  
Pressure Drop ◽  
Separation Efficiency ◽  
Collection Efficiency ◽  
Saddle Points ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Cfd Modeling ◽  
Eddy Simulation ◽  
Discrete Phase ◽  
Rsm Model

The dynamics of hydrocyclones is complex, because it is a multiphase flow problem that involves interaction between a discrete phase and multiple continuum phases. The performance of hydrocyclones is evaluated by using Computational Fluid Dynamics (CFD), and it is characterized by the pressure drop, split water ratio, and particle collection efficiency. In this paper, a computational model to improve and evaluate hydrocyclone performance is proposed. Four known computational turbulence models (renormalization group (RNG) k- ε , Reynolds stress model (RSM), and large-eddy simulation (LES)) are implemented, and the accuracy of each for predicting the hydrocyclone behavior is assessed. Four hydrocyclone configurations were analyzed using the RSM model. By analyzing the streamlines resulting from those simulations, it was found that the formation of some vortices and saddle points affect the separation efficiency. Furthermore, the effects of inlet width, cone length, and vortex finder diameter were found to be significant. The cut-size diameter was decreased by 33% compared to the Hsieh experimental hydrocyclone. An increase in the pressure drop leads to high values of cut-size and classification sharpness. If the pressure drop increases to twice its original value, the cut-size and the sharpness of classification are reduced to less than 63% and 55% of their initial values, respectively.

Numerical Analysis of the Effects of Processing Conditions on the Casting of High Temperature PEMFC Membrane Solutions

2009 ◽  
Author(s):  
Kanthi Latha Bhamidipati ◽  
Tequila A. L. Harris
Keyword(s):  
Pressure Drop ◽  
High Temperatures ◽  
Failure Modes ◽  
Platinum Catalyst ◽  
Cost Effective ◽  
Processing Conditions ◽  
Thermally Induced ◽  
Electrolyte Membranes ◽  
Low Humidity ◽  
Computational Fluid Dynamics Cfd

Polymer Electrolyte Membranes have numerous failure modes resulting from chemical, mechanical and thermal influences. The conventional state–of–the–art low temperature Nafion® membrane is susceptible to such failures due to its sensitivity to high temperatures and the presence of carbon monoxide (CO) in the reactant streams, which poisons the platinum catalyst at low temperatures. To circumvent these problems, novel, cost-effective membranes that operate at high temperatures (>120°C) and low humidity levels, such as phosphoric acid doped polybenzimidazole (PBI/PA) membranes, have been developed. However, an optimized manufacturing process for the PBI membranes is required to negate failure mechanisms that are mechanically and thermally induced; e.g., gas cross-over due to pinholes. This paper focuses on understanding defects arising in the fluid state during manufacturing, using Computational Fluid Dynamics (CFD) techniques. Simulations are performed to understand the effects of processing conditions (substrate velocity, inlet velocity and temperature) on the quality of the cast and pressure drop through the system. It is found that processing speeds affected both the cast quality and pressure drop, while temperature only affected the pressure drop.

scholarly journals Computational Study of Operating Parameters on Performance of Compound Hydrocyclone

2021 ◽  
Vol 9 (VII) ◽  
pp. 2517-2524
Author(s):  
R. Giridhar
Keyword(s):  
Pressure Drop ◽  
Separation Efficiency ◽  
Collection Efficiency ◽  
Computational Study ◽  
Saddle Points ◽  
Turbulence Models ◽  
Pressure Drops ◽  
Eddy Simulation ◽  
Discrete Phase ◽  
Rsm Model

The dynamics of hydro cyclones is complex, because it is a multiphase flow problem that involves interaction between a discrete phase and multiple continuum phases. The performance of hydro cyclones is evaluated by using Computational Fluid Dynamics (CFD), and it is characterized by the pressure drop, split water ratio, and particle collection efficiency. In this paper, a computational model to improve and evaluate hydro cyclone performance is proposed. Computational turbulence models (renormalization group (RNG) k-ε, Reynolds’s stress model (RSM), and large-eddy simulation (LES)) are implemented, and the accuracy of each for predicting the hydro cyclone behavior is assessed. Four hydro cyclone configurations were analyzed using the RSM model. By analyzing the streamlines resulting from those simulations, it was found that the formation of some vortices and saddle points affect the separation efficiency. Furthermore, the effects of inlet width, cone length, and vortex finder diameter were found to be significant. The cut-size diameter was decreased compared to the Hsieh experimental hydro cyclone. An increase in the pressure drops leads to high values of cut-size and classification sharpness. If the pressure drop increases to twice its original value, the cut-size and the sharpness of classification are reduced to their initial values, respectively.

Numerical and Experimental Analysis of Turbulent Flow in Corrugated Pipes

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Henrique Stel ◽  
Rigoberto E. M. Morales ◽  
Admilson T. Franco ◽  
Silvio L. M. Junqueira ◽  
Raul H. Erthal ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Velocity Magnitude ◽  
Geometric Configurations ◽  
Corrugated Surfaces ◽  
Friction Factors

This article describes a numerical and experimental investigation of turbulent flow in pipes with periodic “d-type” corrugations. Four geometric configurations of d-type corrugated surfaces with different groove heights and lengths are evaluated, and calculations for Reynolds numbers ranging from 5000 to 100,000 are performed. The numerical analysis is carried out using computational fluid dynamics, and two turbulence models are considered: the two-equation, low-Reynolds-number Chen–Kim k-ε turbulence model, for which several flow properties such as friction factor, Reynolds stress, and turbulence kinetic energy are computed, and the algebraic LVEL model, used only to compute the friction factors and a velocity magnitude profile for comparison. An experimental loop is designed to perform pressure-drop measurements of turbulent water flow in corrugated pipes for the different geometric configurations. Pressure-drop values are correlated with the friction factor to validate the numerical results. These show that, in general, the magnitudes of all the flow quantities analyzed increase near the corrugated wall and that this increase tends to be more significant for higher Reynolds numbers as well as for larger grooves. According to previous studies, these results may be related to enhanced momentum transfer between the groove and core flow as the Reynolds number and groove length increase. Numerical friction factors for both the Chen–Kim k-ε and LVEL turbulence models show good agreement with the experimental measurements.

The Effect of Different Turbulence Models on the Emitter Discharge by Using Computational Fluid Dynamics

2013 ◽  
Vol 662 ◽  
pp. 586-590
Author(s):  
Gang Lu ◽  
Qing Song Yan ◽  
Bai Ping Lu ◽  
Shuai Xu ◽  
Kang Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulent Model ◽  
Simulation Results ◽  
Rsm Model ◽  
Dynamics Method ◽  
Emitter Discharge

Four types of Super Typhoon drip emitter with trapezoidal channel were selected out for the investigation of the flow field of the channel, and the CFD (Computational Fluid Dynamics) method was applied to simulate the micro-field inside the channel. The simulation results showed that the emitter discharge of different turbulent model is 4%-14% bigger than that of the experimental results, the average discharge deviation of κ-ω and RSM model is 5, 4.5 respectively, but the solving efficiency of the κ-ω model is obviously higher than that of the RSM model.

Computational Investigation of Different Turbulent Models When Predicting Airflow in an Enclosure

2008 ◽  
Author(s):  
Xi Wang ◽  
Hassan Naji ◽  
Ahmed Mezrhab
Keyword(s):  
Numerical Investigation ◽  
Turbulence Models ◽  
Turbulent Stress ◽  
Computational Investigation ◽  
Isothermal Case ◽  
The Mean ◽  
Turbulent Models ◽  
Rsm Model ◽  
Cold Case ◽  
Good Agreement

In the present study, a numerical investigation is carried out for an isothermal case, a hot case and a cold case with FLUENT code. Three turbulence models are considered: the k-ε realisable model, the RNG k-ε model and the RSM linear model. The obtained results are compared to experiments and show generally a good agreement for the mean velocities and temperatures, but less satisfactory for the turbulent stress. The performance of the RSM model is remarkable. Even if none of the models is able to give the exact experimental pattern on the map of turbulence, the RSM model seems able to predict such configuration.

Assessment of Different Turbulence Models in Helically Coiled Pipes Through Comparison With Experimental Data

2012 ◽  
Author(s):  
Marco Colombo ◽  
Antonio Cammi ◽  
Marco E. Ricotti
Keyword(s):  
Turbulent Flow ◽  
Great Influence ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Test Facility ◽  
Wall Functions ◽  
Pressure Drops ◽  
Fully Developed Turbulent Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Helical Geometry

This paper deals with a comprehensive study of fully developed single-phase turbulent flow and pressure drops in helically coiled channels. To the aim, experimental pressure drops were measured in an experimental campaign conducted at SIET labs, in Piacenza, Italy, in a test facility simulating the Steam Generator (SG) of a Generation III+ integral reactor. Very good agreement is found between data and some of the most common correlations available in literature. Also more data available in literature are considered for comparison. Experimental results are used to assess the results of Computational Fluid Dynamics (CFD) simulations. By means of the commercial CFD package FLUENT, different turbulence models are tested, in particular the Standard, RNG and realizable k-ε models, Shear Stress Transport (SST) k-ω model and second order Reynolds Stress Model (RSM). Moreover, particular attention is placed on the different types of wall functions utilized through the simulations, since they seem to have a great influence on the calculated results. The results aim to be a contribution to the assessment of the capability of turbulence models to simulate fully developed turbulent flow and pressure drops in helical geometry.

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