Experimental study of unstable film boiling on a modified heating surface

Abstract

An experimental investigation is conducted on a specific boiling regime of a subcooled water flow, leading to the formation of superintensive heat exchange with a metal heater. To analyze the influence of surface modification, several heaters with different micro-geometries were used: a smooth one with R_c = 0.5 µm and a modified one processed using laser ablation. In the latter case, the surface micro-relief is characterized by a roughness of R_c = 10 µm, as well as the presence of cylindrical protrusions with a height and diameter of 200 µm. The experiments were carried out in a vertical channel at an initial pressure of 0.29 MPa, a maximum heater temperature of 450 °C, and an average flow velocity of 0.52 m/s.