Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Transport phenomena in binary gas mixtures

The fundamental purpose of the research programme concerns theoretical and experimental studies of transport phenomena in binary gas mixtures: rare gas-simple polyatomic gas. Experiments on concentration diffusion and thermal diffusion in helium-carbon monoxide and argon-carbon monoxide systems have been carried out in a two bulbs apparatus at a pressure of 0.5 atmospheres. Data have been obtained for the concentration diffusion coefficient, D12 , and for the thermal diffusion factor, alphaT, for five temperatures in the range 308-356 K and, at each temperature, for three concentrations of the heavy component close to 25, 50 and 75 %. Theoretical comparisons for the system helium-carbon monoxide have already been studied, assuming the infinite order sudden approximation (IOSA) for the ab initio calculations. Seven potential energy surfaces have been considered: Thomas, Kraemer and Diercken potential (TKD potential); Gianturco et al. modification of the TKD potential (POT-11 potential); LeRoy et al. empirical anisotropic potentials, V(3,3,3) and XC9 ; three potentials proposed by Gianturco and Paesani calculated ab initio on the basis of the Hartrie-Fock approximation and on the theory of the density function. Ab initio calculations for potential energy surfaces for the argon-carbon monoxide system is intended. Experiments have also been carried out on concentration diffusion and thermal diffusion in mixtures of technical interest, namely in two helium-fluorocarbon systems that are important in environment studies related with the ozone layer of the Earth's atmosphere.