A STUDY ON CRITICAL HEAT FLUX MECHANISMS AND THE TRANSITION TO FILM BOILING

Abstract

An infrared (IR) thermometry technique was used to study the critical heat flux (CHF) and the transition to film boiling during pool boiling and submerged jet impingement. Highly resolved temporal and spatial heat transfer measurements were obtained by measuring temperature distributions on the surfaces of an IR transparent test heater with a mid-range IR camera. Measurements were obtained for the nucleate boiling regime, CHF, early transition boiling regime, and through the transition to film boiling. The local heat flux, temperature, and dryout characteristics were used to compare the submerged jet and pool boiling conditions. It was found that similar mechanisms govern CHF and the transition to film boiling. This finding supports that the hydrodynamic models are incorrect, and CHF is governed by the surface characteristics and the dynamics of the microlayer.