Numerical simulation of mass transfer in a wiped film molecular distillator

Mass and heat transfer on liquid films are important parameters for the modification and optimization of wiped film molecular distillators. In this paper, a 3-D CFD model of a wiped film molecular distillator was established, which was used to study variations of temperature, concentration, evaporation rate and liquid phase mass transfer rate in three-dimensional direction and explore effects of flow rate and heat evaporationon heat and mass transfer. The results indicate that surface temperature of head wave liquid films gradually reduces along the circumferential and radial direction, while it gradually increases along the axial direction. The temperature gradients are larger at positions including first wave head, wall surface and liquid film surface. The concentration of volatile components keeps unchanged near wall surface, but it decreases in three-dimensional direction. The evaporation rate shows a similar trend as that of temperature in three-dimensional direction. Smaller flow rate, higher heating temperature and higher surface temperature can result in higher evaporation rate and total liquid phase mass transfer coefficient, which is beneficial to mass transfer. However, higher heating temperature will increase production cost and material decomposition. Therefore, appropriate heating temperature should be used. © 2016, Editorial Board of “Journal of Chemical Engineering of Chinese Universities”. All right reserved.