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Diffusion in slurries and in non‐Newtonian fluids
Author(s) -
Clough S. B.,
Read H. E.,
Metzner A. B.,
Behn V. C.
Publication year - 1962
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690080316
Subject(s) - newtonian fluid , viscosity , diffusion , slurry , thermodynamics , work (physics) , non newtonian fluid , rheology , generalized newtonian fluid , mechanics , chemistry , materials science , physics , shear rate
Diffusivities in slurries and in non‐Newtonian solutions are predicted by means of an extension of the general Eyring rate theory. The fluid is considered as consisting of a number of discrete regions, each with its own contribution to the overall diffusion process. This model overcomes the unrealistic effects of fluid viscosity predicted by the conventional (empirical) equations. Whereas diffusivities predicted by means of prior art correlations were as much as 230 times lower than the experimental values in the systems, the maximum error in diffusivities predicted with the equations developed in this work was about 40%. Experimental data are provided on two kinds of fluids: slurries and a polymer solution. Both were highly non‐Newtonian (flow behavior indexes as low at 0.15). Benzoic acid and β napthol were employed as the diffusing solutes. The principal limitation of the experimental data is that only aqueous systems were investigated. Much further experimental work will be required to provide a truly adequate test of the theory and to evaluate the several unknown parameters in sufficient detail to enable highly accurate predictions. Additionally the model used suggests a possible mechanism for increasing diffusion rates in these systems which is worthy of exploration. It may also be applied to an analysis and prediction of diffusion rates in viscous Newtonian fluids, for which no adequate method is presently available.