An experimental study of nucleate pool boiling heat transfer from a Gewa-T finned surface in Freon-113

Abstract

A variety of experimental tests were made with a Gewa-T finned surface in Freon-113 to assist in understanding the physical mechanisms which occur during nucleate pool boiling from this type of surface. The influence of the channels between neighboring T-shaped fins was examined with the use of four aluminum shrouds which had top and bottom windows of various apertures, and which were fitted tightly over the Gewa-T surface. The influence of the fins was examined by progressively machining away the fin height to arrive at a smooth cylindrical surface. The application of the shrouds increased the heat transfer coefficient at low heat fluxes by as much as 153 percent, but decreased the heat transfer coefficient at high heat fluxes when compared to the unshrouded surface. The addition of the "T-caps" to straight fins produced the most significant improvement in heat transfer performance when compared to a smooth tube. Based upon these results, it appears that the heat transfer performance of the Gewa-T surface is mainly influenced by the effect of the channels created by neighboring T-shaped fins.