Sublimation in a Porous Continuum Developed From Nonequilibrium Thermodynamics

1974 ◽  
Vol 96 (3) ◽  
pp. 319-323 ◽  
Author(s):  
M. D. Burghardt ◽  
W. W. Bowley
Keyword(s):  
Mass Transport ◽  
Nonequilibrium Thermodynamics ◽  
Transport Equations ◽  
General Energy ◽  
Sublimation Dehydration

The case of sublimation dehydration of a porous continuum is analyzed from the viewpoint of nonequilibrium thermodynamics. The general energy and mass transport equations are shown and the application of sublimation is illustrated.

scholarly journals Stochastic Risk and Uncertainty Analysis for Shale Gas Extraction in the Karoo Basin of South Africa

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Abdon Atangana ◽  
Gerrit van Tonder
Keyword(s):  
South Africa ◽  
Mass Transport ◽  
Sampling Method ◽  
Latin Hypercube Sampling ◽  
Transport Equations ◽  
Upward Migration ◽  
Karoo Basin ◽  
Fracking Fluid ◽  
Stochastic Risk ◽  
Flow And Mass Transport

We made use of groundwater flow and mass transport equations to investigate the crucial potential risk of water pollution from hydraulic fracturing especially in the case of the Karoo system in South Africa. This paper shows that the upward migration of fluids will depend on the apertures of the cement cracks and fractures in the rock formation. The greater the apertures, the quicker the movement of the fluid. We presented a novel sampling method, which is the combination of the Monte Carlo and the Latin hypercube sampling. The method was used for uncertainties analysis of the apertures in the groundwater and mass transport equations. The study reveals that, in the case of the Karoo, fracking will only be successful if and only if the upward methane and fracking fluid migration can be controlled, for example, by plugging the entire fracked reservoir with cement.

Effects of Mass Transport on the Performance of Solid Oxide Fuel Cells Composite Electrodes

2006 ◽  
Vol 4 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Marco Cannarozzo ◽  
Simone Grosso ◽  
Gerry Agnew ◽  
Adriana Del Borghi ◽  
Paola Costamagna
Keyword(s):  
Fuel Cells ◽  
Mass Transport ◽  
Solid Oxide Fuel Cells ◽  
Gas Diffusion ◽  
Transport Equations ◽  
Solid Oxide ◽  
The Other ◽  
Oxide Fuel ◽  
Composite Electrodes ◽  
The Impact

Composite electrodes are of great interest in the field of solid oxide fuel cells because their use can improve the performance of these cells. However, an important correlation exists between composition, microstructure, and thickness of an electrode and its performance. This correlation has been investigated in this work using a theoretical model. The model, in order to consider all the losses occurring in an electrode, includes Ohm’s law for ionic and electronic charge transport, and the Butler-Volmer equation to evaluate the activation polarizations, and mass transport equations, taking into account diffusion through porous media, to evaluate the concentration losses. The model shows that the best electrode performance is a trade-off between activation and concentration losses. This is because a decrease in the dimensions of the particles or an increase in its thickness result, on the one hand, in a reduction of the activation polarizations, because of a larger active area for the electrochemical reaction, and, on the other hand, in an increase in the concentration losses due to a more difficult gas diffusion. In particular, in order to understand the impact of concentration losses on the performance of composite electrodes, the simulations have been run with two models, one including and the other one neglecting the mass transport equations. The results show that concentration losses play a role only with thick electrodes composed of small particles, operating at high fuel utilization.

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