Spatial Distribution of Active Sites and Bubble Flux Density

Abstract

<p>An experimental investigation is presented for boiling of water at atmospheric pressure on a single copper surface. The distribution of active site was investigated at different levels of heat flux and subcooling. The results obtained indicated that the active sites were distributed randomly on the heating surface, since the distribution of active sites followed the Poisson distribution.</p> <p>Changes in heat flux and subcooling did not affect the distribution of active sites, although additional active sites formed among the sites which had been already activated when heat flux was increased.</p> <p>The frequency of vapour bubble emission and the bubble flux density have been studied as well. The results obtained showed that the surface superheat had a great effect on the vapour bubble emission frequency, although the influence of subcooling was of lesser significance. The bubble flux density showed a marked tendency to cluster and was not uniformly distributed over the heating surface.</p>