Measurements on thermodiffusion in ternary hydrocarbon mixturesat high pressure

摘要

Experimental investigations on thermodiffusion have been conducted for five different ternarymixtures of methane, n-butane, and n-dodecane at a high temperature and pressure. While the molefraction of methane was fixed at 0.2 the mole fraction of n-dodecane was varied from 0.7 to 0.2. Theexperiments were performed in a microgravity environment on board the satellite FOTON-M3. Itwas found that in all mixtures, n-dodecane separated to the cold side whereas methane segregatedto the hot side. n-butane, the species with an intermediate density, showed a change in sign as itsmole fraction was increased. At low concentrations it collected on the cold side but moved in theopposite direction with an increase in its mole fraction. The role of the relative density coupled withthe species concentrations has been used to explain the thermodiffusion factor in each mixture.Computational investigations showed a similar behavior. However, the theoretical model was notable to capture the sign change of n-butane accurately. The inadequate representation of thesignificance of the relative densities and the mole fraction of the species has been found as thereason for this.