Performance of a liquid thermal-diffusion column with temperature asymmetry over the width

The theory of thermal diffusion 1] employs an idealized model in which the temperature at all points on the hot or cold surface is assumed to be the same. In practice, however, such a model cannot be realized, since even the most careful design of the column will result in asymmetry in the temperature distributions on these surfaces. This asymmetry is more pronounced in liquid columns because of the small width of the annulus, and so the column acquires parasitic convection 1], which results in resolution worse than theory predicts. The origin of this effect, which is extremely undesirable in practical operation is explained in Fig. 1a 1]. The azimuthal temperature gradient in regions I and II causes the mean temperature of the liquid to vary, so the liquid as a whole moves in one direction in region I and in the opposite direction in region II; in each of these regions there are also two flows caused by the radial temperature gradient, which is incorporated in the theory of the column.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 5, pp. 809–817, November 1970.One prime and two primes refer, respectively, to the column parts shown in Fig. 1 as I and II.