Prediction of Liquid Film Dryout in Two-Phase Annular-Mist Flow in a Uniformly Heated Narrow Tube Development of Analytical Method under BWR Conditions
A method was developed based on the conservation lows to predict critical heat flux (CHF) causing liquid film dryout in two-phase annular-mist flow in a uniformly heated narrow tube under BWR conditions. The applicable range of the method is within the pressure of 3-9MPa, mass flux of 500-2, 000kg/m<SUP>2</SUP>•s, heat flux of 0.33-2.0MW/m<SUP>2</SUP> and boiling length-to-tube diameter ratio of 200-800.<BR>The two-phase annular-mist flow was modeled with the three-fluid streams with liquid film, entrained droplets and gas flow. Governing equations of the method are mass continuity and energy conservation on the three-fluid streams. Constitutive equations on the mass transfer which consist of the entrainment fraction at equilibrium and the mass transfer coefficient were newly proposed in this study.<BR>Confirmation of the present method were performed in comparison with the available film flow measurements and various CHF data from experiments in uniformly heated narrow tubes under high pressure steam-water conditions. In the heat flux range (q"<2MW/m<SUP>2</SUP>) practical for a BWR, agreement of the present method with CHF data was obtained as, (Averaged ratio)±(Standard deviation)=0.984+0.077, which was shown to be the same or better agreement than the widely-used CHF correlations.
- Journal of nuclear science and technology
Journal of nuclear science and technology 35(9), 643-653, 1998-09-25
Atomic Energy Society of Japan