E205 STUDY ON FORCED-CONVECTION FILM BOILING HEAT TRANSFER : HEAT TRANSFER CHARACTERISTICS IN HIGH REYNOLDS NUMBER REGION AND BEHAVIOR OF LIQUID-VAPOR INTERFACE(Boiling two-phase flow)

概要

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The forced-convection film boiling heat transfer was investigated experimentally focusing on the heat transfer mechanism, the transition condition, the correlation and the behavior of liquid-vapor interface on film boiling heat transfer in high liquid Reynolds number region. Quenching tests of a vertical-long-thick cylindrical pipe were conducted for subcooled R-113 at a pressure of 0.1 MPa. The test section made of pure copper was 50, 15 and 110 mm in outer diameter, thickness and height, respectively. A range of bulk-liquid velocity was 0.1 to 10 m/s. The characteristics of the heat-transfer coefficients for the velocity of R-113 flow above 2.4m/s were qualitatively close to the Dittus-Boelter type correlation based upon the turbulent flow. A correlation using Nusselt number, Reynolds number, Prandtl number and density-viscosity ratio was presented for experimental data on some liquids. The critical condition on the film boiling heat transfer characteristics was about Re_1=3.4×10^4 for R-113 flow. Furthermore, it was noticeable that thickness of vapor film in the film boiling at the critical condition was just as that of the viscous sublayer in turbulent boundary layer of the bulk liquid. The liquid-vapor interface in the film boiling tended to be smooth as the liquid velocity increased.
一般社団法人日本機械学会の論文
2000-10-01