Diffusion of ideal gases in capillaries and porous solids

Abstract

The steady state diffusion of gases through capillaries or through the pores of a solid when fusion, bulk flow of the gases is free to the total pressure in the system is constant is considered. I t is shown that the ratio of the molar occur, but in the present situation diffusion rate of the lighter gas to that of the heavier gas must be equal to the square root such bulk flow is effectively prohibited by the mechanics of flow in the fine of the ratio of the molecular weight of the heavier to the lighter. diffusion for a constant pressure sys-

Diffusion of Gases in Porous Solids. II. Diffusion of an Isotope Trace through Binary Gaseous Mixtures in a Porous Graphite

“…The mean value of (aAc/B,,) ,,,,, calculated for the same mixtures from the bulk diffusion data (14, 15) is 1.196. Thus [22], and hence [3], is valid. However, the ratio of the a effects extrapolated to zero pressure gives for the ratio of the Knudsen diffusion coefficients of Kr and Xe a value soinewhat different from that predicted by [2] (Table 8).…”

“…The form of the S.D.-E.W.M. model applicable to our experiments can be derived by specializing the equation for multi-component diffusion (19) for the case where NA = -N,*, NB = 0, and x,, is sufficiently small to be neglected in comparison to x,, and adding a term for Knudsen diffusion, thus If, following Scott, [3] is assumed to hold for porous media, then Now DL, is pressure independent and bulk gaseous diffusion coefficients are proportional to lip where K, , is some function of the molecular properties of A and B, so [12] may be put in the form where and Using the cell constant F and [7], [14] may be rewritten…”

“…Previous workers (3)(4)(5)(6)10) have concentrated on the first two parts of the problem by observing the counter diffusion of a pair of essentially nonadsorbable gases such as He, N,, Ar, and 0,. We attempted to solve the first part of the problem only.…”

“…Figures 1 and 2 show5 a, and a,' respectively plotted against logp, while Figs. [3][4][5] show the linearity obtained using [8] for regression of the active gas, inactive gas, and concentration effects. Our analysis gave the model + e l l i j k t r where…”

IRRADIATION PERFORMANCE OF THORIA-URANIA FUEL MATERIALS. Quarterly Technical Report No. 1, May-September 1964

“…Liquid-volume displacement27,28 and flowmeters, such as 31 the wet-test gas meter , rotanneter 24,33,36 , and bubble meter25 have 23,35 been used to measurethe volumetric flow.…”