Prediction of Liquid Film Dryout in Two-Phase Annular-Mist Flow in a Uniformly Heated Narrow Tube Development of Analytical Method under BWR Conditions

• Published in: Journal of nuclear science and technology 1998-09, Vol.35 (9), p.643-653
• Main Authors: UTSUNO, Hideaki, KAMINAGA, Fumito
• Format: Article
• Language: English
• Subjects: annular-mist flow; Applied sciences; BWR type reactors; critical heat flux; deposition; droplets; Energy; Energy. Thermal use of fuels; entrainment; Exact sciences and technology; Fission nuclear power plants; heated tube; Installations for energy generation and conversion: thermal and electrical energy; liquid film dryout; three-fluid streams; tight lattice
• ISSN: 0022-3131; 1881-1248
• DOI: 10.1080/18811248.1998.9733920

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 3-9 MPa, mass flux of 500-2,000 kg/m 2 ·s, heat flux of 0.33-2.0 MW/m 2 and boiling length-to-tube diameter ratio of 200-800. 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. 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"