scholarly journals Capabilities and Limitations of 3D-CFD Simulation of Anode Flow Fields of High-Pressure PEM Water Electrolysis

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 968
Author(s):  
Christoph Haas ◽  
Marie-Gabrielle Macherhammer ◽  
Nejc Klopcic ◽  
Alexander Trattner
Keyword(s):  
High Pressure ◽  
Liquid Water ◽  
Single Phase ◽  
Cfd Simulation ◽  
Flow Analysis ◽  
Two Phase ◽  
Gaseous Oxygen ◽  
Geometry Model ◽  
Exact Geometry ◽  
Phase Liquid

In this work, single-phase (liquid water) and two-phase (liquid water and gaseous oxygen) 3D-CFD flow analysis of the anode of a high pressure PEM electrolysis cell was conducted. 3D-CFD simulation models of the anode side porous transport layer of a PEM electrolyzer cell were created for the flow analysis. For the geometrical modelling of the PTL, two approaches were used: (a) modelling the exact geometry and (b) modelling a simplified geometry using a porosity model. Before conducting two-phase simulations, the model was validated using a single-phase approach. The Eulerian multiphase and the volume-of-fluid approaches were used for the two-phase modelling and the results were compared. Furthermore, a small section of the PTL was isolated to focus on the gas bubble flow and behaviour in more detail. The results showed plausible tendencies regarding pressure drop, velocity distribution and gas volume fraction distribution. The simplified geometry using the porous model could adequately replicate the results of the exact geometry model with a significant reduction in simulation time. The developed simulation model can be used for further investigations and gives insight into two-phase flow phenomena in the PTL. Additionally, the information obtained from simulation can aid the design and evaluation of new PTL structures.

scholarly journals Numerical Model for Cavitational Flow in Hydraulic Poppet Valves

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Sandor I. Bernad ◽  
Romeo Susan-Resiga
Keyword(s):  
Liquid Flow ◽  
Bubble Dynamics ◽  
Flow Analysis ◽  
Cavitating Flow ◽  
Absolute Pressure ◽  
Two Phase ◽  
Current Effort ◽  
Flow Models ◽  
Density Distributions ◽  
Phase Liquid

The paper presents a numerical simulation and analysis of the flow inside a poppet valve. First, the single-phase (liquid) flow is investigated, and an original model is introduced for quantitatively describing the vortex flow. Since an atmospheric outlet pressure produces large negative absolute pressure regions, a two-phase (cavitating) flow analysis is also performed. Both pressure and density distributions inside the cavity are presented, and a comparison with the liquid flow results is performed. It is found that if one defines the cavity radius such that up to this radius the pressure is no larger than the vaporization pressure, then both liquid and cavitating flow models predict the cavity extent. The current effort is based on the application of the recently developed full cavitation model that utilizes the modified Rayleigh-Plesset equations for bubble dynamics.

A Robust Asymptotically Based Modeling Approach for Two-Phase Flow in Porous Media

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
M. M. Awad ◽  
S. D. Butt
Keyword(s):  
Porous Media ◽  
Pressure Gradient ◽  
Single Phase ◽  
Present Model ◽  
Flow In Porous Media ◽  
Pressure Gradients ◽  
Two Phase ◽  
New Model ◽  
Proposed Model ◽  
Phase Liquid

A simple semitheoretical method for calculating the two-phase frictional pressure gradient in porous media using asymptotic analysis is presented. The two-phase frictional pressure gradient is expressed in terms of the asymptotic single-phase frictional pressure gradients for liquid and gas flowing alone. In the present model, the two-phase frictional pressure gradient for x≅0 is nearly identical to the single-phase liquid frictional pressure gradient. Also, the two-phase frictional pressure gradient for x≅1 is nearly identical to the single-phase gas frictional pressure gradient. The proposed model can be transformed into either a two-phase frictional multiplier for liquid flowing alone (ϕl2) or a two-phase frictional multiplier for gas flowing alone (ϕg2) as a function of the Lockhart–Martinelli parameter X. The advantage of the new model is that it has only one fitting parameter (p), while the other existing correlations, such as the correlation of Larkins et al., Sato et al., and Goto and Gaspillo, have three constants. Therefore, calibration of the new model to the experimental data is greatly simplified. The new model is able to model the existing multiparameter correlations by fitting the single parameter p. Specifically, p=1/3.25 for the correlation of Midoux et al., p=1/3.25 for the correlation of Rao et al., p=1/3.5 for the Tosun correlation, p=1/3.25 for the correlation of Larkins et al., p=1/3.75 for the correlation of Sato et al., and p=1/3.5 for the Goto and Gaspillo correlation.

Experimental Study on Two-Phase Flows in Scavenge Pump for Aircraft Engine Oil System

2016 ◽  
Author(s):  
Laurent Ippoliti ◽  
Olivier Berten ◽  
Patrick Hendrick
Keyword(s):  
Single Phase ◽  
Aircraft Engine ◽  
Engine Oil ◽  
Test Rig ◽  
Feed Pump ◽  
Two Phase ◽  
Turbofan Engine ◽  
Flow Capacity ◽  
Scavenge System ◽  
Phase Liquid

This work is the continuation of previous studies on gerotor-type pump performance in turbofan engine oil systems operated as feed pumps in single-phase liquid oil. The focus here is on scavenge pumps whose role is to pump a mix of air and oil. This paper is intended to present the modifications that had to be made on the test rig from the previous studies to model a scavenge system and more generally to add two-phase flow capacity. The paper presents results from the first successful experimental test campaign. The aim is to characterize the performance of a typical pump, already tested as a feed pump, in the scavenge system. The critical performance parameter studied is the volumetric efficiency which determines the size and weight of the pump. This paper ends by drawing conclusions on the rig and the results, and linking them with the previous single-phase flows studies.

scholarly journals Simulation of Drag Reducer Polymer (DRP) for Single and Annular Two Phase Flow in Horizontal Pipe

2018 ◽  
Vol 13 (2) ◽  
pp. 154-164
Author(s):  
Cindy Dianita ◽  
Asep Handaya Saputra ◽  
Puteri Amelia Khairunissa
Keyword(s):  
Drag Reduction ◽  
Annular Flow ◽  
Single Phase ◽  
Cfd Simulation ◽  
Fluid Velocity ◽  
Flow Equation ◽  
Equation Model ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase

Drag reducing polymers (DRP) is one of drag reducer types that is widely used in industry as an additive to improve fluid flow efficiency in pipes. This study is conducted to analyze the parameters that influence the efficiency of DRP through developing equation model, and to see the phenomenon of drag reduction that occurs in fluid flow through computational fluid dynamic (CFD) simulation. The data used are obtained from experiments by Vancko (1997) for a single phase flow of water. As for two-phase annular flow, four experiments data are used namely by Vancko (1997), Al-Sarkhi and Hanratty (2001a,b) and Fernandes et al. (2004). Parameters such as fluid velocity and pipe diameter are analyzed based on the model equations proposed in this study. The final single phase flow equation model as the output of this study gives a value for onset drag reduction i.e 4.00 with an error up to 18%. While the proposed annular flow equation with and without drag reduction effect is only suitable when the condition of fluid film distribution is uniform and symmetrical with the error around 20%, i.e. for smaller diameter pipes. The CFD simulation results shows a change in the fluid velocity profile; becoming more parabolic, indicating an increase in the mean fluid velocity up to 0.43%, as the effect of DRP.

A Robust Asymptotically Based Modeling Approach for Two-Phase Flow in Porous Media

2008 ◽  
Author(s):  
M. M. Awad ◽  
S. D. Butt
Keyword(s):  
Porous Media ◽  
Pressure Gradient ◽  
Single Phase ◽  
Theoretical Method ◽  
Flow In Porous Media ◽  
Pressure Gradients ◽  
Two Phase ◽  
New Model ◽  
Proposed Model ◽  
Phase Liquid

A simple semi-theoretical method for calculating two-phase frictional pressure gradient in porous media using asymptotic analysis is presented. Two-phase frictional pressure gradient is expressed in terms of the asymptotic single-phase frictional pressure gradients for liquid and gas flowing alone. In the present model, the two-phase frictional pressure gradient for x ≅ 0 is nearly identical to single-phase liquid frictional pressure gradient. Also, the two-phase frictional pressure gradient for x ≅ 1 is nearly identical to single-phase gas frictional pressure gradient. The proposed model can be transformed into either a two-phase frictional multiplier for liquid flowing alone (φl2) or two-phase frictional multiplier for gas flowing alone (φg2) as a function of the Lockhart-Martinelli parameter, X. The advantage of the new model is that it has only one fitting parameter (p) while the other existing correlations such as Larkins et al. correlation, Sato et al. correlation, and Goto and Gaspillo correlation have three constants. Therefore, calibration of the new model to experimental data is greatly simplified. The new model is able to model the existing multi parameters correlations by fitting the single parameter p. Specifically, p = 1/3.25 for Midoux et al. correlation, p = 1/3.25 for Rao et al. correlation, p = 1/3.5 for Tosun correlation, p = 1/3.25 for Larkins et al. correlation, p = 1/3.75 for Sato et al. correlation, and p = 1/3.5 for Goto and Gaspillo correlation.

scholarly journals Modelling of Boiling Flows for Nuclear Thermal Hydraulics Applications—A Brief Review

Inventions ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 47
Author(s):  
Giovanni Giustini
Keyword(s):  
Heat Transfer ◽  
Liquid Water ◽  
Cfd Simulation ◽  
High Surface ◽  
Computational Modelling ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Thermal Hydraulics ◽  
Two Phase ◽  
Water Reactors

The boiling process is utterly fundamental to the design and safety of water-cooled fission reactors. Both boiling water reactors and pressurised water reactors use boiling under high-pressure subcooled liquid flow conditions to achieve high surface heat fluxes required for their operation. Liquid water is an excellent coolant, which is why water-cooled reactors can have such small sizes and high-power densities, yet also have relatively low component temperatures. Steam is in contrast a very poor coolant. A good understanding of how liquid water coolant turns into steam is correspondingly vital. This need is particularly pressing because heat transfer by water when it is only partially steam (‘nucleate boiling’ regime) is particularly effective, providing a great incentive to operate a plant in this regime. Computational modelling of boiling, using computational fluid dynamics (CFD) simulation at the ‘component scale’ typical of nuclear subchannel analysis and at the scale of the single bubbles, is a core activity of current nuclear thermal hydraulics research. This paper gives an overview of recent literature on computational modelling of boiling. The knowledge and capabilities embodied in the surveyed literature entail theoretical, experimental and modelling work, and enabled the scientific community to improve its current understanding of the fundamental heat transfer phenomena in boiling fluids and to develop more accurate tools for the prediction of two-phase cooling in nuclear systems. Data and insights gathered on the fundamental heat transfer processes associated with the behaviour of single bubbles enabled us to develop and apply more capable modelling tools for engineering simulation and to obtain reliable estimates of the heat transfer rates associated with the growth and departure of steam bubbles from heated surfaces. While results so far are promising, much work is still needed in terms of development of fundamental understanding of the physical processes and application of improved modelling capabilities to industrially relevant flows.

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