Effects of Non-Uniform Temperature of the Walls on the Soret Experiment

We present a numerical study of a Soret experiment, which is conducted in a cell filled with a binary mixture and placed between differently heated horizontal walls. In real experiments, in the corner regions of the cell, where glass is in contact with metal, the uniformity of temperature can be perturbed. We study the effect of the temperature non-uniformity on the Soret separation considering two variable parameters: the local deviation of temperature from the value on the rest of the wall, and the length of the interval on which temperature perturbations occur. The cases of symmetric and non-symmetric perturbations are examined. Our non-linear numerical simulations reveal two distinct regimes of mass transfer in a mixture with Soret effect: diffusive and convective. The diffusive regime is sustained until temperature non-uniformity less than 3-5% of the applied temperature difference and occupies 5% of the wall length at each corner. In the convective regime, the emerging flow prohibits component separation by mixing of liquid components. It is noted a strong flow appears at the earliest moment of the experiment which rapidly attenuates.SCOPUS: ar.j