Rupture of a Subcooled Liquid Film Falling Down a Heated Grooved Surface

This paper presents an experimental study of rupture of a subcooled water film falling down an 1 m long heated copper plate with longitudinal grooves of 0.5x0.15 mm(2) cross sectional area and 2 mm spacing. It was found that the threshold heat flux at which an initial stable dry patch forms on the grooved surface is about two times higher than that on a smooth surface. Furthermore, the grooves prevent dry patches from spreading over the total heated surface thus essentially delaying the onset of the heat transfer crisis. The main governing parameters of the experiment and their respective values are: initial film temperature (20-95 degrees C), heat flux (0-1.26 W/cm(2)) and volumetric flow rate (11.1-38.2 l/h) (Re=56.2-653.2).