Experimental Study on Behaviors of Two Successive Bubbles in Subcooled Flow Boiling at High Degrees of Subcooling

摘要

Subcooled flow boiling is an effective heat transfer approach and used widely in industries. In this paper, an experimental study was conducted on the bubble behaviors in subcooled flow boiling in an upward annular flow at relatively high degrees of subcooling. The bubble images during its whole lifetime were captured with high spatial and temporal resolutions by using a high speed video camera and a Cassegrain telemicroscope. The degree of subcooling in this study was above 30 K. The phenomenon of two successive bubbles was observed and analyzed. This phenomenon was caused by the severe deformation of the first bubble departing from the wall, and the second bubble grows from the remaining vapor of the first bubble after its departure from the wall. Consequently, its dynamical behaviors were strongly influenced by the first bubble. Quantitative data were also obtained to analyze the bubble behavior, such as the maximum size of the second bubble was smaller than the first one, and both the growth and condensation rates of the second bubble were slower than the first bubble.