Condensation of FC-72

摘要

Heat transfer coefficients for condensing FC-72~® vapor on vertical copper and Teflon plates are reported as a function of sub-cooling at one atmosphere. Results include the evolution of the average heat transfer coefficient with time and a visual record of droplet formation and coalescence owing to non-condensable gas. Experiments are run for a Reynolds number of 15.1, wall heat flux of 0.92-2.88 W/cm~2, and 6-44 K sub-cooling. Film condensation heat transfer coefficients compare reasonably well with those of prior studies run under different convective conditions. High resolution video captures evolution of droplet size (average diameter) and number density. A correlation is shown to exist between overall heat transfer coefficients and droplet size and number density. When droplet number density exceeds 10 cm~2 and droplet area exceeds ～1.5 mm~2, average heat transfer coefficients approach a limiting value.