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Journal of Flow Visualization and Image Processing

ISSN Print: 1065-3090
ISSN Online: 1940-4336

Journal of Flow Visualization and Image Processing

DOI: 10.1615/JFlowVisImageProc.v12.i3.40
pages 271-284

NUMERICAL VISUALIZATION OF TURBULENT FILM BOILING HEAT TRANSFER AND VAPOR FILM GROWTH ON HORIZONTAL ELLIPTICAL TUBES

Sheng-An Yang
Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, TAIWAN (R. O. C.)
Jung-Yu Lee
Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, TAIWAN (R. O. C.)
Wen-Jei Yang
University of Michigan, Ann Arbor, Michigan 48109

ABSTRACT

Numerical visualization is conducted to investigate turbulent film boiling heat transfer and vapor film growth on horizontal isothermal elliptical tubes. The effects of both eddy diffusivity and thermal radiation are taken into account. Theellipticity, heat capacity parameter, radiation parameter, and wal-to-saturated-vapor temperature ratio are varied to determine their effects on turbulent film boiling heat transfer performance and vapor film growth. It is concluded that the vapor film grows monotonically around the periphery of the elliptic tube from the lower to upper stagnation point. In contrast, the local Nusselt number is enhanced, reaching a maximum value and then diminishing rapidly along the lower to upper stagnation point. The average Nusselt number is augmented with an increase in both the ellipticity and temperature ratio. Results compared satisfactorily well with the existing experimental data obtained using Freon 12 and liquid nitrogen as the boiling media.