Page 76 - Adsorption Technology & Design, Elsevier (1998)
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Rates of adsorption of gases and vapours by porous media 73
Figure 4.1 Ratio of measured to calculated diffusivities as a function of porosity
(source: Currie 1960).
conform to a monodisperse nor a bidisperse porous structure. If f(r)dr is the
volume fraction of pores having a size between r and (r + dr) then the
effective diffusivity may be calculated from the integral
oo
De = - D(r)f(r)dr (4.14)
~2 0
arising from the parallel pore model of Johnson and Stewart (1965). The
integral can be evaluated numerically provided the volume distribution of
pores is known from a pore size analysis.
