Some results for reflux condensation of hydrocarbon vapour mixtures

This paper presents some data for condensation of pure and mixed vapours from a new reflux condenser research facility at NEL. The facility contains a single tube test condenser and a dump condenser to allow partial condensation in the test condenser. Single component data for condensation of iso-octane are well predicted using a correction to the Nusselt theory for gravity-controlled condensation for the effects of waves and turbulence. Some initial data for condensation of mixtures of pentane and iso-octane are compared with the predictions of a Colburn and Drew model. The basic Colburn-Drew model gave good agreement with the measured overall heat transfer coefficient, but underestimated the vapour composition and temperature changes. Improved agreement with the data could be obtained by enhancing the diffusive heat and mass transfer coefficients to allow for the relative velocity of the liquid and vapour phases and for the effects of waves on the condensate film. However, the measured separation of the components was still significantly greater than predicted.