The rate of thermal diffusion in mixtures of carbon dioxide and hydrogen

Abstract

An equation is derived for the time rate of change of composition of a binary gas mixture of initially uniform composition by thermal diffusion in an apparatus consisting of two chambers, one above the other, connected by a straight tube. The upper chamber is held at a given constant high temperature and the lower chamber at a given constant lower temperature. Using the thermal conductivity method of analysis the rate of change of composition in the lower chamber has been measured for carbon dioxide-hydrogen mixtures for various compositions, pressures and higher temperatures. From the experimental results and the derived equation, values are determined for the thermal diffusion coefficient, the ordinary or concentration diffusion coefficient and the temperature exponent for these coefficients.