Numerical study on the nano-droplets formation process from superheated steam condensation flow effected by nozzle convergent profile

Abstract

Based on the phase transition phenomenon of nano-droplets formed from the condensation flows of superheated steam, a mathematical model appropriate for predicting the process of condensation flows is developed under the Eulerian- Eulerian two-phase flow reference frame, and then the effects of the convergent profile for nozzle on the condensation flows process of superheated steam are numerically investigated using the commercial computational fluid dynamics package FLUENT as computational platform. The results show that the nano-droplets are formed when the phase transition from steam to liquid occur within the ultra-limited time and space scale. With the shrink of subsonic convergent profile being slow, the delay effect of condensation flow phenomenon of superheated steam appears, thereby resulting in a raft of changes involving the backward moving of the position of phase transition from condensation, the consequent increasing in the amount and decreasing in the size of nano-droplets as well as lowering in steam humidity of vapor-droplet two phase mixing systems.