Introduction During gas ventilation, gas transport within the alveolar sac is dominated by diffusion. In liquid ventilation, perfluorocarbon (PFC) introduced into the alveolar space acts as a diffusion barrier to gas transport since the diffusivities of oxygen and carbon dioxide in this medium are four orders of magnitude lower than in air. Therefore convection in the PFC layer resulting from t...

The diffusivities of methane in single-walled carbon nanotubes (SWNTs) are investigated at various temperatures and pressures using classical molecular dynamics (MD) simulations complemented with grand canonical Monte Carlo (GCMC) simulations. The carbon atoms at the nanotubes are structured according to the (m, m) armchair arrangement and the interactions between each methane molecule and all ...

In the current work, we present a comprehensive modeling framework to predict the effective gas diffusivity, as a function of liquid water saturation, based on realistic 3-D microstructures of the uncompressed as well as compressed gas diffusion layer (GDL). The presented approach combines the generation of a virtual microscopic GDL and different physical modeling. We develop a reduced model in...

A one dimensional isothermal mathematical modeling of cathode side of a Proton Exchange Membrane (PEM) fuel cell is developed for the water management problem. Water transport is investigated in both cathode Gas Diffusion Layer (GDL) and membrane through solving appropriate equations for fluid flow and mass transport in GDL and water transport within the membrane. The gaseous mixture flowing in...

in this study, mass transfer coefficients (mtc’s) of natural gas components during hydrate formation are reported. this work is based on the assumption that the transport of gas molecules from gas phase to aqueous phase is dominant among other resistances. several experiments were conducted on a mixture of natural gas at different pressures and temperatures and the consumed gas was monitored an...

The transport resistance of oxygen in a PEMFC flow field and gas diffusion layer interface was numerically investigated in a 3D model. This model solved for the convection of air and the diffusion of oxygen in the air in a single flow field channel. The interfacial oxygen transport resistance was expressed with the Sherwood number. For a dry channel, the numerically obtained Sherwood number was...

A measurement system for current distribution mapping for a PEFC has been developed. The segmented anode is constructed so as to have high thermal conductivity in order to prevent the formation of large temperature gradients between the electrodes. The construction is therefore feasible for use at high current densities. Both segmented and unsegmented gas diffusion layers are used. The effect o...

Gas diffusion medium (GDM) is a crucial component in proton exchange membrane fuel cells (PEMFCs). Being composed of a gas diffusion layer (GDL) with a micro-porous layer (MPL) coated onto it, it ensures a proper water management due to the highly hydrophobic materials employed in cell assembly. In current commercial applications, the desired water repellent behaviour is usually obtained by usi...

In this work, molecular dynamics (MD) was performed to simulate the dynamic processes of 1:4 acetone/nitrogen permeating through different Al2O3 membranes by Materials Studio 2.2 software package. Three modeling systems were constructed applying different modeling box lengths as well as different hollow size and texture of Al2O3 membranes to compare different permeation behaviors. In each syste...