Numerical Modeling and Experimental Analysis of Air-Droplet Interaction in the Channel of a Proton Exchange Membrane Fuel Cell

2010 ◽  
Vol 7 (3) ◽  
Author(s):  
Angelo Esposito ◽  
Aaron Motello ◽  
Cesare Pianese ◽  
Yann G. Guezennec
Keyword(s):  
Fuel Cell ◽  
Water Transport ◽  
Gas Flow ◽  
Air Flow ◽  
Gas Diffusion ◽  
Mean Value ◽  
Proton Exchange ◽  
Computational Time ◽  
Droplet Growth ◽  
Experimental Apparatus

An accurate low order model (mean value model) that captures main water transport mechanisms through the components of a PEM fuel cell was developed. Fast simulation time was achieved through a lumped approach in modeling the space-dependent phenomena. Evaporation and capillarity were assumed to be the predominant mechanisms of water flow through the gas diffusion media. The innovative features of the model are not only to simulate the water transport inside the porous media with relative simplicity, but also to simulate the water transport at the interface between the gas diffusion layer and gas flow channel. In order to preserve a light computational burden, the complex air flow-droplet interaction was modeled with several simplifying assumptions, and with the support of measured data. The physics that characterizes the single droplet-air flow interaction was analyzed with an experimental apparatus constructed to study the droplet growth and detachment process. Furthermore, the experimental findings were exploited to feed the numerical model with the missing theoretical information, and empirical submodels to guarantee accuracy. Thanks to the followed fast computational time of the mean value approach, the model is suitable for fuel cell design and optimization, as well as diagnosis and control strategies development studies.

Numerical Modeling and Experimental Analysis of Air-Droplet Interaction in the Channel of a PEM Fuel Cell

2009 ◽  
Author(s):  
Angelo Esposito ◽  
Aaron Motello ◽  
Cesare Pianese ◽  
Yann G. Guezennec
Keyword(s):  
Fuel Cell ◽  
Water Transport ◽  
Gas Flow ◽  
Air Flow ◽  
Pem Fuel Cell ◽  
Gas Diffusion ◽  
Mean Value ◽  
Computational Time ◽  
Droplet Growth ◽  
Experimental Apparatus

An accurate low order model (MVM, Mean Value Model) that captures the main water transport mechanisms through the components of a PEM Fuel Cell was developed. Fast simulation time was achieved through a lumped approach in modeling space-dependent phenomena. Evaporation and capillarity were assumed to be the predominant mechanisms of water flow through the gas diffusion media. The model innovative features are not only to simulate the water transport inside the porous media with relative simplicity but also to simulate the water transport at the interface between gas diffusion layer and gas flow channel. In order to preserve a light computational burden, the complex air flow–droplets interaction was modeled with several simplifying assumption and with the support of measured data. The physics that characterizes the single droplet-air flow interaction was analyzed with an experimental apparatus constructed to study the droplet growth and detachment process. Furthermore, the experimental findings were exploited to feed the numerical model with the missing theoretical information and empirical sub-models to guarantee accuracy. Thanks to the fast computational time of the mean value approach followed, the model is suitable for fuel cell design and optimization as well as diagnosis and control strategies development studies.

A Low Order Control-Oriented Model of Liquid Water Transport in PEM Fuel Cell

2008 ◽  
Author(s):  
Angelo Esposito ◽  
Cesare Pianese ◽  
Yann G. Guezennec
Keyword(s):  
Fuel Cell ◽  
Water Transport ◽  
Diffusion Layer ◽  
Liquid Water ◽  
Gas Diffusion Layer ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Computational Time ◽  
Liquid Water Transport

In this work, an accurate and computationally fast model for liquid water transport within a proton exchange membrane fuel cell (PEMFC) electrode is developed by lumping the space-dependence of the relevant variables. Capillarity is considered as the main transport mechanism within the gas diffusion layer (GDL). The novelty of the model lies in the simulation of the water transport at the interface between gas diffusion layer and gas flow channel (GFC). This is achieved with a phenomenological description of the process that allows its simulation with relative simplicity. Moreover, a detailed two-dimensional visualization of such interface is achieved via geometric simulation of water droplets formation, growth, coalescence and detachment on the surface of the GDL. The accomplishment of reduced computational time and good accuracy makes the model suitable for control strategy implementation to ensure PEM fuel cells operation within optimal electrode water content. Furthermore, the model is useful for optimization analysis oriented to both PEMFC design and balance of plant.

scholarly journals The Effects of the PEM Fuel Cell Performance with the Waved Flow Channels

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Yue-Tzu Yang ◽  
Kuo-Teng Tsai ◽  
Cha’o-Kuang Chen
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Gas Flow ◽  
Gas Diffusion ◽  
Flow Channel ◽  
Proton Exchange ◽  
Electrical Performance ◽  
Wave Number ◽  
Gap Size ◽  
Fuel Cell Performance

The objective of this study is to use a new style of waved flow channel instead of the plane surface channel in the proton exchange membrane fuel cell (PEMFC). The velocity, concentration, and electrical performance with the waved flow channel in PEMFC are investigated by numerical simulations. The results show that the waved channel arises when the transport benefits through the porous layer and improves the performance of the PEMFC. This is because the waved flow channel enhances the forced convection and causes the more reactant gas flow into the gas diffusion layer (GDL). The performance which was compared to a conventional straight gas flow channel increases significantly with the small gap size when it is smaller than 0.5 in the waved flow channel. The performance is decreased at the high and low velocities as the force convection mechanism is weakened and the reactant gas supply is insufficient. The pressure drop is increased as the gap size becomes smaller, and the wave number decreases. (gap size)δ> 0.3 has a reasonable pressure drop. Consequently, compared to a conventional PEMFC, the waved flow channel improves approximately 30% of power density.

Effect of Gravity on Droplet Growth and Detachment Inside a Simulated PEM Fuel Cell Air Flow Channel With Hydrophobic Walls

2013 ◽  
Author(s):  
Andres Munoz ◽  
Abhijit Mukherjee
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Air Flow ◽  
Pem Fuel Cell ◽  
Proton Exchange ◽  
Droplet Growth ◽  
Flow Rates ◽  
Air Supply ◽  
Supply Channel ◽  
Exchange Membrane

Water management still remains a challenge for proton exchange membrane fuel cells. Byproduct water formed in the cathode side of the membrane is wicked to the air supply channel through the gas diffusion layer. Water emerges into the air supply channel as droplets, which are then removed by the air stream. When the rate of water production is higher than the rate of water removal, droplets start to accumulate and coalesce with each other forming slugs consequently clogging the channels and causing poor fuel cell performance. It has been shown in previous experiments that rendering the channels hydrophobic or super-hydrophobic cause water droplets to be removed faster, not allowing time to coalesce, and therefore making channels less prone to flooding. In this numerical study we analyze water droplet growth and detachment from a simulated hydrophobic air supply channel inside a proton exchange membrane (PEM) fuel cell. In these numerical simulations the Navier-Stokes equations are solved using the SIMPLER method coupled with the level set technique in order to track the liquid-vapor interface. The effect of the gravity field acting in the −y, −x, and +x directions was examined for an array of water flow rates and air flow rates. Detachment times and diameters were computed. The results showed no significant effect of the gravity field acting in the three different directions as expected since the Bond and Capillary numbers are relatively small. The maximum variations in detachment time and diameter were found to be 8.8 and 4.2 percent, respectively, between the horizontal channel and the vertical channel with gravity acting in the negative x direction, against the air flow. Droplet detachment was more significantly affected by the air and water flow rates.

Investigation of Water Vapor Diffusivity Through GDL of a PEMFC

2009 ◽  
Author(s):  
Jacob LaManna ◽  
Satish G. Kandlikar
Keyword(s):  
Mass Transfer ◽  
Water Vapor ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Effective Diffusivity ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Transfer Model ◽  
Operational Conditions ◽  
Experimental Apparatus

Water transport through the gas diffusion layer (GDL) of a proton exchange membrane (PEM) fuel cell is of critical importance in the operation of the fuel cell. In this study, the transport of water vapor through the GDL is investigated. A one-dimensional, single-phase heat and mass transfer model is developed to investigate the diffusivity of water vapor through the GDL of a PEMFC. An experimental apparatus is developed to induce water vapor gradients across the GDL while varying humidity levels and flow rates comparable to actual fuel cell operational conditions. Experimental data is then used to extract an effective water vapor diffusivity from the numerical model. Effective diffusivity was found to be 0.104×10−4 m2/s and the overall mass transfer coefficient was found to be 0.019 m/s at a temperature of 40°C.

Effect of Gas Diffusion Layer Surface Wettability Gradient on Water Behavior in a Serpentine Gas Flow Channel of Proton Exchange Membrane Fuel Cell

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Sneha Malhotra ◽  
Sumana Ghosh
Keyword(s):  
Fuel Cell ◽  
Diffusion Layer ◽  
Gas Flow ◽  
Proton Exchange Membrane ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Flow Channel ◽  
Proton Exchange ◽  
Surface Wettability ◽  
Exchange Membrane

Water removal and behavior, in proton exchange membrane fuel cell (PEMFC) gas flow channel has been investigated in this work. Single serpentine gas flow channel has been simulated. Hydrodynamics of water drops in a serpentine channel are studied as a function of nature of gas diffusion layer (GDL) surface wettability. In one case, the surface becomes gradually hydrophobic starting from 90 deg to 170 deg. In this second case, the value of contact angle reduces to 10 deg. A three-dimensional model has been developed by using cfd software. Two different drop of diameter 0.2 mm and 0.4 mm are simulated for all the cases. It is observed that, water coverage is always lesser for a gradual hydrophobic surface. Also at low air velocity and gradual hydrophobic GDL surface results in lesser pressure drop as well as water coverage.

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