The thermal diffusion in binary gaseous mixtures while a third component is being added is studied. A modified two-bulb method is used for experimental measurements. The thermal diffusion factor (TDF) measurements are performed for gaseous systems, containing He, Ar,      and  held under atmospheric pressure and at cold- and hot-chamber temperatures of  and  respectively. For every gas mixture, measurements are made at different values of the mole fraction of the additive. The dependence of the TDFs on the additive’s mole fraction and mass of molecules is studied. To calculate TDF values, a proposed semi-empirical formula is used; calculation results coincide with experimental data within the respective limits of experimental error.

mass transfer, binary gaseous system, experiment, ternary gas mixture, thermal diffusion factor, two-bulb method.