Determination of the thermodiffusion coefficient in three binary organic liquid mixtures by the thermogravitational method (contribution of the Universidad del Pais Vasco, Bilbao, to the benchmark test)

Within the framework of an international benchmark test, the thermodiffusion coefficients D-T of the three binary systems formed with dodecane, isobutylbenzene and 1,2,3,4-tetrahydronaphthalene (with a mass fraction of 0.5 for each component at a temperature of 25degreesC) have been measured. Convective coupling in cylindrical thermogravitational columns has been used to determine DT based on the Furry-Jones-Onsager theory. For each system, several columns with different gaps and heights were employed. Our results for these three coefficients are in good agreement with those obtained by other benchmark tests; the maximum deviation from the proposed benchmark values is 8.5%, which is not too bad owing to the difficulties of measuring a thermodiffusion coefficient.