A Simple Model to Evaluate Direct Contact Heat Transfer and Flow Characteristics in Annular Two Phase Flow

Calculations are performed to study the behavior of air-water mixtures in vertical flows employing a simple model for the description of mass, momentum, and energy transfer in annular gas-liquid flows. The model is applied to various flow conditions including thermal nonequilibrium and variable cross section ducts. Theoretical results agree reasonably well with experimental data regarding well-known isothermal flows. A contribution is provided to the understanding of the two-phase mixtures interactions for gas-liquid internal heat transfer in two-phase, annular, nonisothermal flows.