internal diffusion

internal diffusion

[in′tərn·əl di′fyü·zhən]
(chemical engineering)
The diffusion of liquid or gaseous reactants to the innermost pore depths of an adsorbent-base catalyst, necessary for full catalytic effect.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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Broadening this view, Wu, Gu and Zhang (2008) bring cycles with four capabilities: acquisition, assimilation, internal diffusion and improvement and synergy.
The mass transfer process is considered as internal diffusion controlled, so the first kind of boundary condition is adopted to the model, which means moisture content [C.sub.r,b] on the boundary, surface of which is exposed to helium atmosphere, is constant.
[17], in examining the dynamic process of peanut protein extracted by enzyme-containing reverse micelles, found that the rate-determining step in this extraction process may be the internal diffusion control.
Formaldehyde emission from wood composites includes mainly three mass transport processes: (1) the internal diffusion process: the diffusion of formaldehyde from inside the wood composites to the surface; (2) the thermodynamic equilibrium process: absorption and stripping of formaldehyde between the air and the source interface; and (3) the convection transfer process: the diffusion of formaldehyde from the source boundary layer to the air.
In the outer diffusion zone, the controlling factor is the effect of C[O.sub.2] diffusing to coke surface, while the internal diffusion zone is affected by both chemical reaction and diffusion.
In general, porous adsorbents show many steps in adsorption process [20]; such as, a) Internal diffusion, b) External diffusion and c) Surface diffusion.
* The tradeoff between a battery's useful power and energy capacity is partly the result of internal diffusion dynamics.
Leaf internal diffusion conductance limits photosynthesis more strongly in older leaves of Mediterranean evergreen broad-leaved species.
Correlations between the internal diffusion and equilibrium partition coefficients of volatile organic compound (VOCs) in building materials and the VOC properties.
If we analyze from the viewpoint of mass transfer resistance, the small convective mass transfer coefficient corresponds to large boundary layer resistance ([1/[h.sub.m1]) and it becomes analogous to the internal diffusion resistance (L/[D.sub.e,trad]).
To gauge the influence of knowledge diffusion on economic growth, this study proposes that VC provides an internal diffusion channel in addition to the external diffusion channel for enhancing TFP growth.

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