Confirmation of the pressure history theory of boiling nucleation

Nucleation of the liquid-vapour phase change at surface cavities, and in particular the pressure history model of nucleation, is reviewed. An apparatus and procedure for obtaining reproducible values of initial superheat in pool boiling of water are described. An important aspect of the procedure is heating of the test section to 220 degrees C prior to each measurement. The results confirm the theory in showing a linear dependence of vapour pressure at nucleation on previously imposed deactivation pressure, over the deactivation pressure range 0.35 to 7.0 bar.