An SEM Study of Nucleation Sites in Pool Boiling From 304 Stainless Steel

Abstract

A Scanning Electron Microscope (SEM) was used to examine pool boiling nucleation sites on 304 stainless steel in contact with distilled, degassed water. Nucleation sites were located during the boiling process by noting the coordinates of the bubble locations on the surface. These locations were then magnified using the SEM and photographs made of the nucleation sites. The radii of the cavities varied from 14.8μ-in. to 180μ-in. and the widths of grooves varied from 75μ-in. to 154μ-in.

Selective Ultrasonic Cavitation on Patterned Hydrophobic Surfaces

“…The drastic change in surface texture in this case may be due to the fact that initially formed pits present secondary nucleation sites. [24,29] Altogether, these results confirm the expectation according to Equation (1) that a higher contact angle causes a lower energy barrier, and thus cavitation occurs predominantly at the hydrophobic surface.…”

Reexamination of correlations for nucleate site distribution on boiling surface by fractal theory

“…In general we should have the following relation: g8 = KIR"" (7) where N, is the number of the total nucleate sites on boiling surface and R is the radii of counting circle. In general we should have the following relation: g8 = KIR"" (7) where N, is the number of the total nucleate sites on boiling surface and R is the radii of counting circle.…”

Elements of Boiling Heat Transfer

“…It is difficult to obtain quantitative information by a n a l y z i n g surface roughness parameters or by studying photographs such as those obtained by a scanning electron microscope (Nail et al [11]), as it is not clear which "pits" represent potential active nucleation sites. Gas diffusion experiments patterned after that of Brown [12] have also been attempted, but also with limited success (Lorenz et al [13], Eddington et 4 al.…”