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electro-osmotic
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Numerical study on water distribution in different layers of direct methanol fuel cells
, Article Journal of the Electrochemical Society ; Vol. 161, issue. 8 , 2014 , pp. E3110-E3124 ; ISSN: 00134651 ; Baghalha, M ; Sharif University of Technology
Abstract
In this paper, a two-dimensional, two-phase, isothermal model is presented to investigate the water transport characteristic and water distribution in a direct methanol fuel cell (DMFC) with emphasis on exploring the water distribution in different layers of DMFC. The liquid-gas two-phase mass transport in the porous anode and cathode is formulated based on multi-fluid model in porous media and water and methanol crossover through the membrane are considered with the effect of diffusion, electro-osmotic drag, and convection. The modeling results agree well with the three different experimental data in an extensive range of operation conditions. A parametric study is also performed to examine...
Modeling water content distribution in the polymer electrolyte membrane of pem fuel cell
, Article ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology. Collocated with ASME 2011 5th International Conference on Energy Sustainability, FUELCELL 2011, 7 August 2011 through 10 August 2011, Washington, DC ; 2011 , Pages 851-858 ; 9780791854693 (ISBN) ; Roshandel, R ; Sharif University of Technology
Abstract
Models play an important role in fuel cell design and development. One of the critical problems to overcome in the proton exchange membrane (PEM) fuel cells is the water management. In this work a steady state, two dimensional, isothermal model in a single PEM fuel cell using individual computational fluid dynamics code was presented. Special attention was devoted to the water transport through the membrane which is assumed to be combined effect of diffusion, electro osmotic drag and convection. The effect of current density variation distribution on the Water content (λ) in membrane/electrode assembly (MEA) was determined. After that detailed distribution of oxygen concentration, water...
Enhancing active electro-kinetic micro-mixer efficiency by introducing vertical electrodes and modifying chamber aspect ratio
, Article Chemical Engineering and Processing - Process Intensification ; Volume 142 , 2019 ; 02552701 (ISSN) ; Sani, M ; Saidi, M. S ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Micro-mixers are considered as vital components of Micro Total Analysis systems (μTAS). Major objective in the design of micro-mixers is achieving high mixing quality in short mixing times. In this paper, numerical simulation of some micro-mixer designs has been carried out to understand the detailed flow pattern and thereby to propose modifications for improving mixing efficiency. It is well known that inducing convection will provide turbulent like behavior with corresponding mixing enhancement. In micro systems to drive the flow, electro-osmotic force is usually used by introducing electrodes. In this work, mixing electrodes have been implemented to induce convection and eddies. This...
Numerical simulation for efficient mixing of newtonian and non-Newtonian fluids in an electro-osmotic micro-mixer
, Article Chemical Engineering and Processing: Process Intensification ; Volume 107 , 2016 , Pages 11-20 ; 02552701 (ISSN) ; Mirzakhanloo, M ; Dabirzadeh, M. R ; Sharif University of Technology
Elsevier
2016
Abstract
The present study, deals with a new mixing technique using a two-phase electrode array, which is charged with alternating current (AC) signals, located in specific parts of the geometry. This significantly contributes to a chaotic mixing mechanism using a low amplitude AC voltage within a micro-channel. Study analysis demonstrates that the optimization of the effective parameters such as geometrical features, voltage amplitude, fluid inlet velocity, AC frequency and phase lag for a defined fluid can lead to an optimum and highly efficient mixer by considerably increasing disturbances in a primary highly ordered laminar flow. Three different geometries of micro mixer are studied; one-ring...
Thermally developing electroosmotic flow of power-law fluids in a parallel plate microchannel
, Article International Journal of Thermal Sciences ; Volume 61 , 2012 , Pages 106-117 ; 12900729 (ISSN) ; Saidi, M.H ; Veisi, H ; Fattahi, M ; Sharif University of Technology
2012
Abstract
The present investigation considers the thermally developing electroosmotic flow of power-law fluids through a parallel plate microchannel. Both the viscous dissipation and Joule heating effects are taken into account and a step change in wall temperature is considered to represent physically conceivable thermal entrance conditions. Expressions for the dimensionless temperature and Nusselt number in the form of infinite series are presented. In general, the resultant eigenvalue problem is solved numerically; nevertheless, an analytical solution is presented for the regions close to the entrance. A parametric study reveals that increasing amounts of the Peclet number result in higher wall...
The effect of fuel cell operational conditions on the water content distribution in the polymer electrolyte membrane
, Article Renewable Energy ; Volume 36, Issue 12 , December , 2011 , Pages 3319-3331 ; 09601481 (ISSN) ; Roshandel, R ; Sharif University of Technology
2011
Abstract
Models play an important role in fuel cell design and development. One of the critical problems to overcome in the proton exchange membrane (PEM) fuel cells is the water management. In this work a steady state, two-dimensional, isothermal model in a single PEM fuel cell using individual computational fluid dynamics code was presented. Special attention was devoted to the water transport through the membrane which is assumed to be combined effect of diffusion, electro-osmotic drag and convection. The effect of current density variation distribution on the water content (λ) in membrane/electrode assembly (MEA) was determined. In this work the membrane heat conductivity is considered as a...