Abstract:

At present，the liquid film model is widely used for predicting critical heat flux in gas-liquid annular flow.The model consists of the following parameters：onset of annular flow，entrainment fraction at the onset point and the equilibrium state，inception criteria for droplet entrainment，droplets deposition and entrainment rates，which all have predominant effects on the prediction accuracy.Most parameters in this model can be determined by some empirical correlations，which are valid in specific conditions.However，up to now，the entrainment fraction at the onset of annular flow has been always assumed.In this paper，based on the experimental data with steam-water as working fluid and obtained from the pressure range of 0.18—0.27 MPa，a new correlation was proposed for the entrainment fraction at the onset of annular flow，which could make the errors between calculations and experiments within 20%.