Two-phase flashing flow in conduits

Abstract

The two-phase flashing flow in conduits is analyzed. The continuity, momentum and energy equations for a one-dimensional homogeneous flow model are derived. The two components are treated as pseudo-fluid having average properties. These equations relate the pressure, quality ratio, flow rate, conduit geometry, the rate of flashing and the distance along the conduit. Also, two correlations are developed by the use of dimensional analysis and the available experimental data for horizontal and vertical conduits. The correlations relate the flow rate, pressure drop, initial pressure and conduit geometry for flashing flow in conduits between flashing chambers. Simultaneous solution of the continuity and momentum equations is performed numerically using a modified Rung-Kutta-Gill method. The developed correlations together with a semi-empirical expression for the rate of flashing developed earlier by Dickson and Silver ( 1) are applied to develop polynomial equations expressing physical properties such as saturated temperature, vapor specific volume, enthalpy and latent heat in terms of pressure by the least square method. The expressions are then used in solving the equations. The solution gives the distribution of pressure, quality, and velocity along the conduit length for horizontal conduits. The equations for vertical conduits are given and the same method can be applied to obtain their solution.