Influences of feed and condenser temperature on molecular distillation of ideal binary mixtures

Balanced equations of a binary mixture for molecular distillation (MD) were derived on the basis of relation of heat and mass transfer in liquid films on both the evaporating and condensing surface. Effects of feed temperature and condenser temperature on film thickness, film surface temperature and concentration, degree of evaporation and concentration of distillate were analyzed for MD. The length of evaporating cylinder along with surface temperature of evaporating film reached steady state decreasing with increasing of feed temperature. Evaporation rate decreased with increasing of condenser temperature because of re-evaporation. Influences of splashing on distillate and re-evaporation were minimized and gradient concentration of distillate and increased degree of evaporation were obtained by the divided evaporator and condenser. Evaporating film temperature was increased with the gradient increase of divided evaporator temperature. Mode of divided molecular still could be used for the separation of mixtures with largely different saturated pressure at one stage operation. Model values agreed well with the experimental values of Cvengros. Maximum relative differences did not exceed 5.1%.