Abstract
This paper deals with the liquid-vapor structure under vapor mass in the high heat flux region of water and R141b. The liquid-vapor structure was measured in two dimensional space by an optical fiber probe (tip diameter < 10 μm). Experimental data were analyzed with emphasis upon the void fraction, the vapor contact frequency to which the boundary of liquid-vapor contacted at the tip of the optical fiber probe, and the time series of optical probe signal with surface temperature. Time-space averaged results confirm the existence of a liquid layer and very rapid liquid-vapor phase-changes in the liquid layer in water. On the other hand, the time-space averaged results of R141b do not indicate the existence of the liquid layer. This suggests that the liquid-vapor structure of R141b differs from that of the water and the so-called macrolayer model owing to its small surface tension.
