NOTES ON THE LIQUID-METAL BOILING PHENOMENON

Abstract

A brief review of boiling for ordinary fluids with emphasis on the wall superheat required for bubble initiation from different sur-faces at varying pressures is presented. Calculations based on an equation valid for normal fluids indicate that superheats from two to eight times that for water are required to initiate a vapor bubble in some of the alkali metals. This high superheat and the high ther-mal conductivity peculiar to liquid metals are combined to explain the unstable liquid-metal boiling phenomenon in natural- and forced-circulation loops. Forced-convection boiling-potassium heat-transfer coefficients correlated by the Lockhart-Martinelli two-phase flow parameter are in reasonable agreement with the forced-convection boiling-water data of Dengler and Addoms. Some recommendations on bubble initiation sites and future wor