A Study on the Boiling Heat Transfer from Flat Surfaces under High Heat Flux : 2nd Report, Nucleate Boiling from Vertical Surfaces and Upward Facing Horizontal Surfaces

Abstract

Pool boiling of water from a vertical surface and two upward-facing flat surfaces was experimentally studied under atmospheric pressure by making use of the apparatus described in the first report. The range of heat flux covered the entire region of nucleate boiling up to the burnour limit. The shape of the curve showing the relation between the heat flux and the temperature difference was similar to the curve for thin wires. When the heat flux exceeded 4×105 kcal/m2h, bubbles coalesced on the heating surface before leaving it. In the vicinity of the burnout limit, very large lumps of vapor rose intermittently from the heating surface. Experimental equations were set up by making use of Stanton number for the heat transfer coefficient, Reynolds number for the steam velocity leaving the surface, and the size of the heating surface.