The nature of wall temperature distributions in regions of deteriorated heat transfer

This note concerns the difficulty of fitting heat transfer correlations to data in deteriorated forced convective flows of supercritical pressure fluids. Experimental data suggests that the heat transfer coefficient depends inversely upon wall to bulk temperature difference, causing the wall temperature to become very sensitive to secondary features such as axial conduction in the test section wall. Under certain conditions the wall temperature level cannot be uniquely determined by a correlation. It is suggested that by noting the transient response of wall temperature to step changes in heat flux the influence of axial conduction may be deduced.