Steam Condensation on Various Gold Surfaces

Abstract

Gold surfaces were investigated as promoters of dropwise condensation (DWC) of steam at atmospheric pressure. Very high heat fluxes at low ΔT’s may be achieved in this manner. Seven gold electroplating baths, one electroless immersion gold bath, and vacuum vapor deposition of gold were used. Five surface preparations for pure gold were tested. Gold deposits ranged in thickness up to 20,000 A.U. Auger electron spectroscopy and scanning electron microscopy were used to describe the surfaces chemically and physically. Deposits from the bright pure gold plating baths and the “acid, hard” baths promoted DWC. Deposits from alloyed baths, the ultrapure bath, and vapor deposition gave mixed or filmwise condensation. Two surface preparations on solid gold gave DWC, one gave mixed, and two gave filmwise condensation. The results indicate that gold provides an oxide-free surface which adsorbs trace organics from the surroundings. These promote DWC.

Gold surfaces for condensation heat transfer

“…It gives the atomic analysis of a surface, but unfortunately does not identify compounds. The technique was used in conjunction with the heat transfer tests described in this article (27). Carbon, undoubtedly present as organic compounds, was detected on every surface which produced dropwise condensation.…”

“…A study of the minimum gold requirement to obtain dropwise condensation was carried out (27) varying the electroplating process. Brief consideration was also given to electroless immersion deposition and to vacuum deposition of gold on topper.…”

The development and application of advanced analytical methods to commercial ICF reactor chambers. Final report

“…However, it can be shown that the following relation approximates Eq. (4) to a high degree of accuracy (to within less than 0.5%).…”

“…Dropwise condensation is senerally the preferred mode of condensation because the resulting heat transfer coefficient may be as much as an order of magnitude higher than that for film condensation under comparable circumstances. Recent studies by Westwater and co-workers [4,5] have demonstrated that dropwise condensation of steam can be consistently obtained on gold and silver surfaces. The occurrence of dropwise condensation on gold and silver surfaces would appear to contradict the reasoning that high-surface-energy metal surfaces should be well wetted by the liquid phase, producing film condensation instead of dropwise condensation.…”

“…In collaboration with Professor P. Peterson from the University of California -Berkeley, results for spherical shelIs were reported at the 12th Topical Meeting on the Technology of Fusion Power [3]. Hemispherical shells were investigated by Sprague and results are presenting in his undergraduate thesis [4]. Perforated plates were studied using finite element and experimental techniques by Kaap and [7].…”