Numerical Study on Pool Film Boiling of Liquid Hydrogen over Horizontal Cylinders

Due to the low boiling point of hydrogen, the boiling phenomenon is usually encountered in the applications of liquid hydrogen. The underlying mechanism as well as the physical performance of film boiling over horizontal cylinders are not yet fully understood, especially for the various diameters. In this paper, pool film boiling of hydrogen over horizontal cylinders with diameters ranging from 0.2 to 30 mm is investigated based on the volume-of-fluid method. By the analysis of the gas-liquid interface evolution and the heat transfer mechanism, the cylinders are divided into wire heaters, transition heaters, and tube heaters. The results show that the heat transfer of the wire is affected by the evolution of a single bubble, while the heat transfer of the tube is mainly affected by the movement of multiple crescent-shaped gas structures along the surface. Besides, with the increase in cylinder diameter, the bubble detachment diameter increases, the heat flux decreases correspondingly, and the bubble growth period experiences a complicated principle.