AN EXPERIMENTAL STUDY OF POST-CHF HEAT TRANSFER IN A 3x3 ROD BUNDLE

Abstract

This chapter describes post-critical heat flux (CHF) heat transfer experiments in a 3×3 rod bundle. The objective of these experiments was to obtain measurements of thermodynamic nonequilibrium in the post-CHF regime and to characterize its effects on two-phase heat transfer. In boiling heat transfer systems a maximum value of heat flux called critical heat flux occurs when the heated surface can no longer support continuous liquid contact. A two-phase heat transfer loop was designed and built specifically for convective boiling heat transfer studies using steam-water mixtures. Each fuel rod simulator was equipped with 12 thermocouples such that two thermocouples were in the lower extension, one thermocouple in the upper extension and the remaining nine were in the test length. The data acquisition system consisted of a HP series 200, 9816A computer, HP 3497A Data Acquisition/Control unit and an HP34S6A Digital Voltmeter with all the devices on a single HP-IB interface bus, and a Bascom-Turner fast multichannel data recorder.