Dispersed flow film boiling

Abstract

Dispersed flow consists of small liquid droplets entrained in a flowing vapor. This flow regime can occur in cryogenic equipment, in steam generators, and during nuclear reactor loss of coolant accidents. A theoretical analysis of dispersed flow film boiling has been performed using mass, momentum and energy conservation equations for both phases. A numerical solution scheme, including wall-to-drop, vapor to drop, and wall-to-vapor heat transfer mechanisms was used to predict wall temperatures for constant heat flux, vertical upflow conditions. Wall temperature predictions were compared to liquid nitrogen, Freon-12 and water data of four separate investigators with reasonable results. A local conditions solution was developed by simplifying the governing equations, using conclusions from the numerical model. A non-dimensional group was found which solely determined the non-equilibrium with the flow, and allowed hand calculation of wall temperatures. The local conditions solution was compared to data taken by five investigators with good results.