An approach to the kinetics of barrier formation of supercritical gas bubbles in a strongly supersaturated liquid solution is presented. A common assumption of uniform reduction of a dissolved gas supersaturation in a liquid solution via stationary diffusion to nucleating gas bubbles is shown to be not applicable to the case of high gas supersaturations. The approach recognizes that the diffusi...

Gas exchange is governed by the combined action of oxygen consumption and carbon dioxide production, and the transport of these gasses by diffusion. The diffusion component is formally neglected and implicitly incorporated in respiration and fermentation parameters of the current Michealis-Menten-based respiration models. The aim was to extend existing modelling approaches by including a diffus...

The large amount of nanoscale pores in shale results in the inability to apply Darcy's law. Moreover, the gas adsorption of shale increases the complexity of pore size characterization and thus decreases the accuracy of flow regime estimation. In this study, an apparent permeability model, which describes the adsorptive gas flow behavior in shale by considering the effects of gas adsorption, st...

in the present study, a new gas diffusion electrode (gde) (based on pt/nafion membrane) is fabricated. the electrochemical results show that the new gde has the highest electrochemical activity toward the oxygen reduction reaction (orr) among the three electrodes. the sem and xrd findings show that a platinum layer can be attached to nafion membrane closely and firmly with a strong peak corresp...

A three-dimensional computational fluid dynamics model of a proton exchange membrane fuel cell (PEMFC) with both gas distribution flow channels and Membrane Electrode Assembly (MEA) is developed. A set of conservation equation is numerically solved by developing a CFD code based on the finite volume technique and SIMPLE algorithm. In this research, some parameters like oxygen consumption, water...

The ability of foam to control the gas mobility in porous media is determined in part by the trapped (stationary) fraction of foam, Xt. The common approach to determining Xt is to replace some part of the gas by a “tracer gas” during the steady-state stage of the experiments and fitting the effluent data to a capacitance mass-transfer model. Diffusion between bubbles is quantified by the film p...

This Letter describes the theoretical structure of the plasma diffusion layer that develops from an initially sharp gas-metal interface. The layer dynamics under isothermal and isobaric conditions is considered so that only mass diffusion (mixing) processes can occur. The layer develops a distinctive structure with asymmetric and highly nonlinear features. On the gas side of the layer the diffu...

Simulations showing the effect of shear on the collisional diffusion of a 2D point vortex gas are compared to theory. For finite shear the diffusion is considerably smaller than previous zero-shear theories predict. Surprisingly, changing the sign of the applied shear changes the diffusion by an order of magnitude.  2001 Elsevier Science B.V. All rights reserved. The self-diffusion of a 2-dime...