On the wetting behavior of surfaces in boiling

Nucleate boiling heat transfer is strongly influenced by surface wettability as characterized the Young's contact angle, [Formula: see text]. The angle usually obtained from measurements on sessile droplets horizontal test surfaces, but in case of water at high temperatures and pressures, text] values droplet experiments appear to be typically 30°–50° higher than needed explain bubble departure sizes for similar surfaces temperatures. We differences between vapor bubbles using adsorption theory Adamson. This suggests that formation pressure boiling, non-wetted inside with a saturated vapor, it will covered an adsorbed liquid layer nanoscale thickness. Droplet experiments, other hand, generally use autoclaves pressurized permanent gases which far below saturation: these relatively dry gases, nanolayer expected absent. suggest presence increase work new wetted amount comparable tension, resulting significant reduction show applying Adamson's model plausible choices unknown parameters, possible magnitude why appears much less sensitive material conditions departing droplets. conclude heated gas rather environments may not relevant should used directly models nucleate boiling.