Fractionation in a one-stage film evaporator can only be done by draining t
he condensate from different heights of a divided condenser. We have shown
the capabilities of this distillation in a short-path (molecular) evaporato
r with a falling liquid film in a model study, taking into account heat and
mass transfer in both liquid films on the evaporating and condensing surfa
ces, and mass transfer in the vapour phase. The data on flows and compositi
ons of fractions were obtained for a binary test mixture at various feed ra
tes, feed compositions, evaporating and condensing temperatures, and at var
ious condenser arrangements. This mode of short-path distillation in an eva
porator with a divided condenser can be used for fractionation and in cases
where recycling of some portion of distillate is required. The comparison
of the experimental results with the model study results shows a satisfacto
ry qualitative agreement between the experiment and the theory. (C) 2000 El
sevier Science S.A. All rights reserved.