Modeling of Water-Steam Slug Flow in Inclined Pipes Undergoing a Heating Process

This work presents a one-dimensional transient mathematical model for the steam-water slug flow. The model is based on the two-fluid modeling technique. This consists in mass and momentum equations for each phase. Total thermal equilibrium was assumed, nucleation is neglected and the difference between steam and water pressures is taken into account. The model was solved using the finite difference technique. The model allows estimating: pressure, steam volume fraction, velocity, mixture temperature, and internal-wall pipe temperature. Different slug frequency correlations were evaluated. It was found that the best prediction of pressure drop was obtained with the Greskovic and Shrier (1971) correlation. The pressure predictions are in agreement with simulations obtained from a commercial simulator.