Heat transfer under high-power heating of liquids. 3. Threshold decrease of heat conduction in supercritical region

Abstract

The peculiarities of heat transfer in isopropanol in the course of rapid transition from the state of compressed liquid to supercritical state along the isobar have been studied experimentally. The temperature plateau mode, as a specific case of the technique of controlled pulse heating of a wire probe was used. The characteristic heating time was of the order of tens milliseconds, the characteristic heating layer thickness was of the order of micrometers. The pressure range was from 1pc to 6pc, where subscript “c” corresponds to the critical point of a substance. A sharp decrease in the heat transfer intensity for supercritical isopropanol with respect to that of subcritical one has been revealed. The similar effect, which was found previously by the technique of constant heating power as well, is uncharacteristic for well-known stationary measurements. A discussion of the origin of discrepancies between the results from pulse and stationary measurements has been initiated by us.