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Effective wall heat transfer coefficients and thermal resistances in mathematical models of packed beds
Author(s) -
Crider J. E.,
Foss A. S.
Publication year - 1965
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.690110613
Subject(s) - heat transfer coefficient , heat transfer , thermodynamics , packed bed , péclet number , mechanics , thermal resistance , chemistry , materials science , physics , chromatography
Expressions are derived for an effective wall heat transfer coefficient useful in one‐dimensional representations of heat transport in packed beds. These expressions are obtained with two mathematical models of a cylindrical packed bed: a partial differential model and a finite stage model. These expressions relate the effective wall heat transfer coefficient, which is a local coefficient, to the actual wall heat transfer coefficient and the bed diameter (and the radial Peclet number in the partial differential model) in regions of the bed where similar temperature profiles obtain. These relations involve a single dominant root of an equation characteristic of the heat balance equations of each model. From these relations, expressions for an effetive thermal resistance of the bed are obtained. For each model, this bed resistance is found to be an approximately linear function of the bed diameter and to be rather insensitive to the actual wall heat transfer coefficient. For each model, an approximate bed resistance is found that is not dependent upon the actual wall heat transfer coeficient and with which the effective wall heat transfer coefficient can be estiamted with an error of less than 7%.