Breaking process of boiling film around a solid hot sphere immersed in forced convection of sub-cooled water

Abstract

Visualization experiments were conducted for the study of the breaking process of the boiling vapor film over the surface of a hot sphere immersed in sub-cooled forced convection. From the experimental results, a distinct circle of quenching front formed on the surface of the sphere during the breaking process. Through the analysis of the motion track of the quenching front, a few qualitative conclusions were drawn. The maximum heat flux occurs on the fully wetted area of the sphere surface after the quenching front passes through. The speed of the quenching front is fluctuated. When the quenching front moves to the middle of the sphere, its velocity increases first and then decreases. The movement of the quenching front on the sphere surface was affected by the temperature of the sphere, the flow rate of the liquid, the sub-cooling degree and the heat dissipation of the support rod. With the increase of liquid velocity or subcooling degree, the movement of the quenching front accelerates.