A parametric study of nucleate boiling on structured surfaces, part I: Effect of tunnel dimensions

This two-part experimental work identifies the effect of geometric dimensions on the boiling performance of ''tunneled'' enhanced boiling surfaces. The surface is formed on an integral-fin tube having a copper foil wrapped over the fin tips. Pores of known diameter and pitch are pierced in the foil cover. Tests were performed on a 19.1-mm diameter horizontal tube using R-11 and R-123 at 26.7 degrees C for heat fluxes from 2 to 70 kW/m(2). The first part of the study defines the effect of the tunnel dimensions. The data show that greater tunnel height and smaller tunnel pitch are preferred Sharp tunnel earners provides greater enhancement.