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ISSN Online: 2377-424X

ISBN Print: 0-89116-299-2

International Heat Transfer Conference 7
September, 6-10, 1982, Munich, Germany

AN IMPROVED INTERFEROMETRIC TECHNIQUE FOR MEASURING BINARY DIFFUSION COEFFICIENTS

Get access (open in a dialog) DOI: 10.1615/IHTC7.2710
pages 497-502

Abstract

An improved technique for the measurement of binary diffusion coefficients is described. The transient diffusion of vapor from a liquid layer through a gas column is examined using a Mach-Zehnder interferometer. A laser light source allows interfero-grams in both vapor and liquid, from which successive simultaneous vapor concentrations in the column and temperature profiles in the liquid are obtained. The boundary condition of zero vapor concentration at the upper end is assured by placing a covered thin porous stainless steel plate at the top of the vapor column, above which a steady flow of fresh gas is maintained. The experiments are started by uncovering the plate with no disturbance of the liquid surface. The effective diffusion column height and the diffusion coefficient are obtained by a least squares fit of the concentration profiles to the solution of the one-dimensional transient diffusion equation. The technique is believed to yield diffusion coefficients with a ±2% uncertainty. Experiments with hexane and atmospheric air are described.