Transient pool boiling from downward-facing curved surfaces

Abstract

Quenching experiments were performed to investigate the effects of wall thickness on pool boiling from downward-facing curved surfaces in water. Experiments employed three copper sections of the same diameter (50.8 mm) and surface radius (148 mm), but of different thicknesses (12.8, 20 and 30 mm). Local and average pool boiling curves were obtained at saturation and 5, 10 and 14 K subcooling. The maximum and minimum film boiling heat fluxes, which increased with increased subcooling, were independent of wall thickness > 19 mm and Biot number >0.8 and 0.008, respectively, indicating that boiling curves for the 20 and 30 mm thick sections were representative of quasi steady-state, but not those for the 12.8 mm thick section. When compared to that of a flat surface section of the same material and dimensions, the average pool boiling curve for the 12.8 mm thick section showed significant increases in the maximum heat flux (from 0.21 to 0.41 MW m −2) and the minimum film boiling heat flux (from 2 to 13 kW m −2) and about 11.5 and 60 K increase in the corresponding wall superheats, respectively.