Wärmeübertragung mit Phasenänderung in verfahrenstechnischen Prozessen

Abstract

AbstractHeat transfer with change of phase in chemical engineering processes. Heat transfer with change of phase in multicomponent fluid systems depends on whether the liquid is homogeneous or consists of several phases. In condensation of vapours where a homogeneous liquid is formed, the temperature of the interface may change considerably, an effect which is mostly neglected in heat transfer calculations. In cases where the liquid consists of several phases heat transfer coefficients may be evaluated to a good approximation. However, an additional heat resistance must be taken into account when the vapour condenses at an immiscible liquid interface. Heat transfer coefficients for boiling of homogeneous liquid mixtures may be derived from those of the pure components and an additional term allowing for the different composition of liquid and vapour. For multicomponent mixtures this term may be evaluated from the terms of the corresponding binary systems. Heat transfer in boiling of immiscible liquid mixtures is mainly governed by the physical properties of the liquid phase adjacent to the heating wall.