Characteristics of liquid–wall contact in post-CHF flow boiling

Abstract

In several industrial applications, highly heated metal channels are quenched by advancing fronts of cold liquid. The transient heat transfer in the vicinity of the advancing quench front governs the dynamics of the overall process, controlling the rate of quench front advancement. Most analyses to date assume that the hot metal in front of the quench front is above the Leidenfrost temperature and cannot sustain direct liquid contacts. This investigation sought to experimentally assess the validity of the no-contact assumption, and to record specific characteristics of such contacts if they occur. In order to detect and record potential liquid contacts in the vicinity of an advancing quench front, a special rapid-response probe was utilized. Tests were carried out with water at atmospheric pressure and over a range of wall superheats and quench front propagation velocities. Analysis of the experimental data provided information on the probability, duration, and time fraction of liquid contacts as functions of wall superheat and distance from the quench front.