Vaporization of thin liquid films.

Abstract

Experimental results are presented for saturated nucleate pool boiling of distilled water and ethyl-alcohol from 1-7/8" diameter Nickel disks with pool depths from 1.0 inch to a thin film of 0.015 inch. Experimental runs were conducted on a mirrorlike surface utilizing distilled water and ethyl-alcohol; on a grooved surface with distilled water as the working fluid; and on a surface covered with 4 layers of Nickel 50 x 40 mesh with distilled water as the working fluid. Results show that liquid level has little effect on the heat transfer coefficient above a level of 0.2 inch on all three test surfaces; however, below 0.2 inch a rapid increase in the heat transfer coefficient occurs with the lowering of the liquid level. Two types of thin film dryout were noted on the mirrorlike surface: dryout under a dome and dryout in absence of a dome. A grooved surface appears to provide a means of obtaining a stable high heat transfer coefficient at liquid films as thin as 0.015 inch.