A correlation for pool entrainment phenomenon

Abstract

The present work aims to study the phenomena of droplet entrainment from water pool in a confined atmosphere, which could be either a consequence of boiling or depressurization. Eventually, these droplets are entrained by the streaming gas (superficial gas velocity) or settling down due to gravity.The number of correlations developed so far quantify the entrainment based on empirical, semi-empirical and theoretical approaches, but they have been generally limited to a specific flow-regime in the water pool, thermal hydraulic conditions or even to a specific geometry. In this context, the present work aims to develop an empirical correlation to cover the flow regimes from bubbly to churn turbulent, and could be applied to a wide range of geometries. The present correlation shows an increase until a maximum entrainment of about 2.10-4, corresponding to superficial gas velocity of 0.05 m/s for bubbly flow regime, and then a slight decrease to 2·10−5, for the transition regime corresponding superficial gas velocity of 0.1 m/s, and a sharp increase in the churn turbulent flow regime as the gas velocity goes up to 5 m/s.The experimental database used to develop the present empirical correlation covers a broader range of boundary conditions, namely pressure [1 bar–15 bar], water pool thermal condition [subcooled – boiling], vessel diameter [0.19 m- 3.2 m], pool diameter [0.1 m–1.4 m], superficial gas velocity up to 5.0 m/s Therefore, the proposed empirical correlation aims to constitute an important tool to transfer the experimental results to reactor application.