HEAT TRANSFER IN AN ANNULAR TWO-PHASE FLOW.

An analytic model is presented for modeling annular-dispersed two-phase flows with heat transfer in a vertical upflow. The analysis incorporates a two-layer liquid film turbulence structure and is supplemented by using two recent developments for the entrainment of liquid droplets in the core. It is shown that the prediction of hydrodynamics and heat transfer from the model depends on the model for entrainment, and that the best prediction is achieved with an entrainment correlation that is not developed from any specific model of the liquid film. The two-layer liquid film turbulence structure also yields predicted heat transfer coefficients that are in better agreement with the experiments that those predicted by utilizing the single-layer model and turbulent velocity profile of single-phase flow.