Two-Phase CFD Model of the Bubble-Driven Flow in the Molten Electrolyte Layer of a Hall–Héroult Aluminum Cell

2015 ◽  
Vol 46 (4) ◽  
pp. 1959-1981 ◽  
Author(s):  
Yuqing Feng ◽  
M. Philip Schwarz ◽  
William Yang ◽  
Mark Cooksey
Keyword(s):  
Cfd Model ◽  
Electrolyte Layer ◽  
Two Phase ◽  
Molten Electrolyte ◽  
Aluminum Cell

scholarly journals CFD analysis of flashing flow in two-phase geothermal turbine design

2020 ◽  
Vol 7 (2) ◽  
pp. 238-250 ◽  
Author(s):  
Sham Rane ◽  
Li He
Keyword(s):  
Water Pressure ◽  
Thermal Power ◽  
Feed Water ◽  
Multiphase Model ◽  
Cfd Model ◽  
East African ◽  
Two Phase ◽  
Power Estimate ◽  
Thermal Plant ◽  
Bubble Number

Abstract A thermal power plant for the East African Rift countries is under study for combined energy and freshwater generation using geothermal water, available at above 500 kPa pressure and temperature exceeding 150°C. This article presents the computational fluid dynamics (CFD) model and analysis of the two-phase turbine used for power generation in this total flow thermal plant. Flash boiling was implemented using a two-fluid multiphase model with the thermal phase-change criteria for heat, mass, and momentum transfer in the CFD solver ANSYS CFX. Initially, flashing flow in a converging–diverging nozzle was validated. This stationary nozzle model was then extended to a curved rotating nozzle reaction turbine and the results of flow and power were evaluated against available test data at 400 kPa feed water pressure under subcooled condition of 117°C and a very low backpressure of 6 kPa. Flow through this turbine was predicted within 8% deviation. An overestimate in thermodynamic power by 30–50% was predicted at speeds below 4000 rpm, while at the design speed of 4623 rpm the deviation was less than 5%. Rotor torque and hence power estimate was found to be dependent on the bubble size, bubble number density, and heat transfer parameters prescribed in the CFD model. The vapour dryness fraction at turbine exit was close to an isentropic expansion vapour quality. The isentropic efficiency was 7.5–17% for the analysed speed range.

Developing an Advance Tire Hydroplaning Model Using Co-Simulation of Fully Coupled FEM and CFD Codes to Estimate Cornering Force

2018 ◽  
Author(s):  
Ashkan Nazari ◽  
Lu Chen ◽  
Francine Battaglia ◽  
Saied Taheri
Keyword(s):  
Cfd Model ◽  
Fluid Structure Interactions ◽  
Two Phase ◽  
Fluid Structure ◽  
The Public ◽  
Element Size ◽  
Road Surfaces ◽  
Computational Fluid Dynamics Cfd ◽  
Fully Coupled ◽  
Surrounding Fluid

Hydroplaning is a phenomenon which occurs when a layer of water between the tire contact patch and pavement pushes the tire upward. The tire detaches from the pavement, preventing it from providing sufficient forces and moments for the vehicle to respond to driver’s control inputs such as breaking, acceleration and steering. This work is mainly focused on the tire and its interaction with the pavement to address hydroplaning. Fluid Structure Interactions (FSI) between the tire-water-road surfaces are investigated through two approaches. In the first approach, the coupled Eulerian-Lagrangian (CEL) formulation was used. The drawback associated with the CEL method is the laminar assumption and that the behavior of the fluid at length scales smaller than the smallest element size is not captured. As a result, in the second approach, a new Computational Fluid Dynamics (CFD) Fluid Structure Interaction (FSI) model utilizing the shear-stress transport k-ω model and the two-phase flow of water and air, was developed that improves the predictions with real hydroplaning scenarios. Review of the public literature shows that although FEM and CFD computational platforms have been applied together to study tire hydroplaning, developing the tire-surrounding fluid flow CFD model using Star-CCM+ has not been done. This approach, which was developed during this research, is explained in details and the results of hydroplaning speed and cornering force from the FSI simulations are presented and validated using the data from literature.

scholarly journals Study on Propellers Distribution and Flow Field in the Oxidation Ditch Based on Two-Phase CFD Model

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2506 ◽  
Author(s):  
Yuquan Zhang ◽  
Chengyi Li ◽  
Yanhe Xu ◽  
Qinghong Tang ◽  
Yuan Zheng ◽  
...  
Keyword(s):  
Flow Field ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Dead Zone ◽  
Production Costs ◽  
Oxidation Ditch ◽  
Cfd Model ◽  
Two Phase ◽  
Flow Field Characteristics ◽  
Increasing Demand

The oxidation ditch (OD) plays an important role in wastewater treatment plants. With increasing demand and production costs, the energy consumption and sludge deposition occurring in the OD must be diminished to enhance its development. In this paper, a two-phase computational fluid dynamics (CFD) model of water and activated sludge examined the flow field characteristics of an OD, consisting of two side-by-side propellers. The system was studied under five configurations, where the spacing between the propellers was set equal to −0.2, −0.1, 0, 0.1, 0.2 times the length of the OD. The viscosity and settling rate of activated sludge was imported in the numerical simulation through a user defined function (UDF). The optimal scheme of the propeller’s power consumption, velocity distribution, and sludge concentration distribution was obtained. The result shows that sludge concentrations are linked with dead zone velocity but not necessarily with low velocities. Experiments confirmed the validity of the velocity flow field simulated by the two-phase CFD model. Overall, these findings form the basis for the propellers distribution optimization and allow a deeper insight into the flow field of OD systems.

scholarly journals Comparative Study of CFD and LedaFlow Models for Riser-Induced Slug Flow

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3733
Author(s):  
Rasmus Thy Jørgensen ◽  
Gunvor Rossen Tonnesen ◽  
Matthias Mandø ◽  
Simon Pedersen
Keyword(s):  
Slug Flow ◽  
Oil And Gas ◽  
Cfd Simulation ◽  
Numerical Models ◽  
Oil And Gas Industry ◽  
Test Facility ◽  
Cfd Model ◽  
Two Phase ◽  
Transient Model ◽  
Vof Model

The goal of this study is to compare mainstream Computational Fluid Dynamics (CFD) with the widely used 1D transient model LedaFlow in their ability to predict riser induced slug flow and to determine if it is relevant for the offshore oil and gas industry to consider making the switch from LedaFlow to CFD. Presently, the industry use relatively simple 1D-models, such as LedaFlow, to predict flow patterns in pipelines. The reduction in cost of computational power in recent years have made it relevant to compare the performance of these codes with high fidelity CFD simulations. A laboratory test facility was used to obtain data for pressure and mass flow rates for the two-phase flow of air and water. A benchmark case of slug flow served for evaluation of the numerical models. A 3D unsteady CFD simulation was performed based on Reynolds-Averaged Navier-Stokes (RANS) formulation and the Volume of Fluid (VOF) model using the open-source CFD code OpenFOAM. Unsteady simulations using the commercial 1D LedaFlow solver were performed using the same boundary conditions and fluid properties as the CFD simulation. Both the CFD and LedaFlow model underpredicted the experimentally determined slug frequency by 22% and 16% respectively. Both models predicted a classical blowout, in which the riser is completely evacuated of water, while only a partial evacuation of the riser was observed experimentally. The CFD model had a runtime of 57 h while the LedaFlow model had a runtime of 13 min. It can be concluded that the prediction capabilities of the CFD and LedaFlow models are similar for riser-induced slug flow while the CFD model is much more computational intensive.

scholarly journals Validation of NEPTUNE-CFD Two-Phase Flow Models Using Experimental Data

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Jorge Pérez Mañes ◽  
Victor Hugo Sánchez Espinoza ◽  
Sergio Chiva Vicent ◽  
Michael Böttcher ◽  
Robert Stieglitz
Keyword(s):  
Experimental Data ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Model Parameters ◽  
Phase Flow ◽  
Cfd Model ◽  
Two Phase ◽  
Flow Models ◽  
Phase Models ◽  
Good Agreement

This paper deals with the validation of the two-phase flow models of the CFD code NEPTUNEC-CFD using experimental data provided by the OECD BWR BFBT and PSBT Benchmark. Since the two-phase models of CFD codes are extensively being improved, the validation is a key step for the acceptability of such codes. The validation work is performed in the frame of the European NURISP Project and it was focused on the steady state and transient void fraction tests. The influence of different NEPTUNE-CFD model parameters on the void fraction prediction is investigated and discussed in detail. Due to the coupling of heat conduction solver SYRTHES with NEPTUNE-CFD, the description of the coupled fluid dynamics and heat transfer between the fuel rod and the fluid is improved significantly. The averaged void fraction predicted by NEPTUNE-CFD for selected PSBT and BFBT tests is in good agreement with the experimental data. Finally, areas for future improvements of the NEPTUNE-CFD code were identified, too.

A self-standing two-fluid CFD model for vertical upward two-phase annular flow

2011 ◽  
Vol 241 (5) ◽  
pp. 1636-1642 ◽  
Author(s):  
Y. Liu ◽  
W.Z. Li ◽  
S.L. Quan
Keyword(s):  
Annular Flow ◽  
Cfd Model ◽  
Two Phase ◽  
Two Fluid

scholarly journals CFD Modeling of Gas-Liquid Flow and Heat Transfer in a High Pressure Water Electrolysis System

2006 ◽  
Author(s):  
V. Agranat ◽  
S. Zhubrin ◽  
A. Maria ◽  
J. Hinatsu ◽  
M. Stemp ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Water Electrolysis ◽  
Phase Flow ◽  
Cfd Model ◽  
Two Phase ◽  
Pressure Water ◽  
Electrolysis System

A high-pressure water electrolysis system has been investigated numerically and experimentally. The advanced CFD model of two-phase flow, which calculated the 3D distributions of pressure, gas and liquid velocities and gas and liquid volume fractions, has been developed to account for all the major components in the system, and appropriate constitutive equations for two-phase flow parameters were selected for various parts of the system, such as the cell stack, riser, separator and downcomer. Heat transfer between the two phases, and between the gas-liquid mixture and cooling coils located in the gas-liquid separator was also accounted for. The model was validated using comparisons of predicted liquid flow rate with the liquid flow rate measured in the downcomer, where a single-phase liquid flow existed. The effects of pressure, current density, number of cells, and bubble size were investigated with the numerical model. The numerical predictions matched the general trends obtained from the experimental results with regard to the effects of pressure and current density on the liquid flow rate. The validated CFD model is being used as a cell design tool at Hydrogenics Corporation.

Three-dimensional, two-phase, CFD model for the design of a direct methanol fuel cell

2006 ◽  
Vol 162 (2) ◽  
pp. 992-1002 ◽  
Author(s):  
Valeri A. Danilov ◽  
Jongkoo Lim ◽  
Il Moon ◽  
Hyuk Chang
Keyword(s):  
Fuel Cell ◽  
Direct Methanol Fuel Cell ◽  
Three Dimensional ◽  
Cfd Model ◽  
Two Phase ◽  
Direct Methanol ◽  
Methanol Fuel Cell

scholarly journals Validation of a CFD Model Predicting the Effect of High Level Lateral Acceleration Sloshing on the Heat Transfer and Pressure Drop in a Small-Scale Tank in Normal Gravity

2018 ◽  
Author(s):  
O. Kartuzova ◽  
M. Kassemi
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Current Model ◽  
Lateral Acceleration ◽  
Small Scale ◽  
Cfd Model ◽  
Two Phase ◽  
Large Eddy Simulation Model ◽  
Tank Pressure ◽  
High Level

A two-phase CFD model is developed to study the effects of sloshing with high level lateral acceleration on the heat transfer and pressure drop in a small scale tank. Computational results are compared to the data provided by a non-isothermal sloshing experiment without phase change conducted by T. Himeno et al. at the University of Tokyo and JAXA in 2011 [1]. The results of the current model are, also, compared to CFD predictions reported by Himeno et al. [2]. A step change in lateral acceleration was applied in the experiment. Different levels of lateral acceleration amplitude, varying between 0G and 0.5G, were considered. CFD results for interface movement and tank pressure are presented and compared in this paper to the experimental data for the case in which the value of lateral acceleration was set to 0.5G. The effects of initial and boundary conditions and turbulence modeling approach on the tank pressure change during sloshing are discussed in detail. The effect of conjugate heat transfer in the tank wall is also studied to show its important role in determining the tank pressure evolution. The results of the Reynolds Averaged Navier Stokes (RANS) models are compared to the results of the Large Eddy Simulation model (LES) to underscore the importance of correctly capturing the effects of turbulence for high fidelity predictions.

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