Temperature polarization in non-isothermal mass transport through membranes

Abstract

The water flux induced by transmembrane temperature gradients through five PTFE membranes has been studied. Two sets of experiments have been carried out. In the first set the temperature difference between the two bulk phases was fixed at 10 K while the mean temperature and the stirring rate were varied independently. The mean temperature values were varied between 30 and 55 °C and the stirring-rate values were varied between 0 and 360 r.p.m. In the second set the mean temperature was fixed at 45 °C and the temperature difference and the stirring rate were varied independently. The temperature difference was varied between 5 and 25 K and the stirring rate was varied as above. The results permit us to obtain a ‘correction factor’ for the temperature polarization in non-isothermal water transport. In the literature this correction factor is supposed to be independent of mean temperature and temperature difference. In the present paper this assumption has been experimentally checked. The experiments state that the correction factor is virtually independent of mean temperature but grows with temperature difference.