In espresso brewing, soluble content is extracted from a bed of ground coffee beans by forcing hot water through the at high pressure. An important part this process infiltration stage in which permeates initially dry bed. This investigated combination x-ray tomography and fluid mechanical modeling. Tomography used to track front via contrast density. The experimental data are compared with one-dimensional unsaturated porous medium flow model, divides into wet regions incorporates pump...

A non-isothermal, two-phase model for a polymer electrolyte fuel cell (PEFC) is presented, analyzed, and solved numerically under three different thermal, two hydrodynamic, modeling assumptions; the consequences of these are then discussed in terms thermal water management performance. The study motivated by recent experimental results that suggest presence previously unreported, thus unmodeled, contact resistances between components PEFCs discrepancy value capillary pressure used authors...

A recently derived numerical algorithm for one-dimensional one-phase Stefan problems is extended the purpose of two-phase moving boundary in which second phase first appears only after a finite delay time; this can occur if change caused by heat-flux condition. In tandem with Keller box finite-difference scheme, so-called immobilization method used. An important component work use variable transformations that must be built into to resolve boundary-condition discontinuity associated onset...

An isothermal two-dimensional liquid phase model for the conservation of mass, momentum, and species in anode a direct methanol fuel cell (DMFC) is presented analyzed. The inherent electrochemistry DMFC active layer reduced to boundary conditions via parameter adaption. developed case when geometry aspect ratio small, it shown that, under realistic operating conditions, model, which nonetheless describes all essential physics full can be derived. significant benefits this approach are that...

An isothermal two-phase ternary mixture model that takes into account conservation of momentum, mass, and species in the anode a direct methanol fuel cell (DMFC) is presented analyzed. The slenderness allows considerable reduction mathematical formulation, without sacrificing essential physics. reduced then verified validated against data obtained from an experimental DMFC outfitted with transparent end plate. Good agreement achieved. effect mass-transfer resistances flow field porous...

High-power positive composite porous electrodes are known to be the main source of impedance increase in batteries based on GEN2 chemistry. The electrodes, both fresh and harvested from coin cells aged an accelerated EUCAR hybrid electric vehicle lifetime matrix, was measured a three-electrode setup results fitted with physically model. A methodology for fitting data, including optimization strategy incorporating global genetic routine, used fit either or simultaneously at different states...

In industrial electrolytic pickling, a steel strip with oxidized surfaces is passed through an aqueous electrolyte between configuration of electrodes, across which potential difference applied. The thereby indirectly polarized, and electrochemical reactions at the surface result in dissolution oxide layer evolution hydrogen oxygen. To obtain better understanding this process, we derive paper mathematical model for predicting potential, current density ionic species distributions vertical...

Vertical cylinders of bubble-enriched, chemically evolved volcanic rock are found in many inflated pahoehoe lava flows. We provide a putative theoretical explanation for their formation, based on description crystallising three-phase (liquid, solid, gas) crystal pile which the water-saturated silicate melt exsolves steam and becomes more silica-rich as it crystallises anhydrous minerals. These resemble pipes that form solidifying binary alloys result sufficiently vigorous porous medium...

Abstract The work presented here examines the surface cracks that can form during continuous casting of near peritectic steels due to volume changes reaction/transformation. investigated samples were collected plant trials from two different steel grades. role and mode reaction/transformation are found depend on composition alloy, resulting in types cracks. effect local variation cooling rate formation present each grade, which be due, for example, oscillation marks, is demonstrated....

Abstract A two‐dimensional, non‐isothermal, two‐phase model of a polymer electrolyte fuel cell (PEFC) is presented. The developed for conditions where variations in the streamwise direction are negligible. In addition, experiments were conducted with segmented comprised net flow fields. The, experimentally obtained, current distributions used to validate PEFC developed. includes species transport and phase change water, coupled conservation momentum mass, porous backing cathode, charge heat...

The formation of an air gap at the mould–metal interface in vertical continuous casting has long been known to have a detrimental effect on efficiency process, and therefore attracted attempts mathematical modelling. While almost all current efforts consist complex three-dimensional numerical simulations phenomenon, this paper considers instead asymptotic model that captures essential characteristics. is thermomechanical derived for geometry, where generalized plane strain approximation...

The dissolution of a solid spherical particle is canonical problem that finds many areas application. In this work, we provide generalized theory takes into account the role forced convection in solvent (or, alternatively, relative motion solvent), showing can be formulated terms four dimensionless parameters. Focusing on case when one these (the Reynolds number) small, consider asymptotic and numerical approaches to problem, with key outcome being method, implemented finite-element software...