An analysis of turbulent film boiling on a sphere with variable wall temperature

摘要

The present theoretical study investigates turbulent film boiling on a sphere immersed in a stagnant saturated liquid. By assuming the cosine function, the condition of variable wall temperature is expressed. The study includes the analysis of non-linear vapour velocity, vapour temperature, thermal property, and Eddy diffusivity in the vapour film; the radiation effect, temperature ratio, and the Rayleigh number are all considered. The result shows that in a free-convection film, when film boiling has higher Rayleigh number, the turbulent film boiling has a better heat transfer efficiency than the laminar one. Finally, a comparison between the results of the present study and those reported in previous studies is presented. It is found that a good agreement exists between them.