Critical point is the end point of liquid-vapor coexistence line. The properties of liquid and vapor become identical in the critical point.
Published in Chapter:
High-Power Heat Transfer in Supercritical Fluids: Microscale Times and Sizes
Pavel V. Skripov (Institute of Thermal Physics, Ural Branch, Russian Academy of Sciences, Russia), Aleksandr D. Yampol'skiy (Institute of Thermal Physics, Ural Branch, Russian Academy of Sciences, Russia), and Sergey B. Rutin (Institute of Thermal Physics, Ural Branch, Russian Academy of Sciences, Russia)
Copyright: © 2021
|Pages: 27
DOI: 10.4018/978-1-7998-5796-9.ch012
Abstract
Non-stationary heat transfer in supercritical fluids at relatively small temporal and spatial scales was studied experimentally. The aim of the study was to clarify the peculiarities of conductive heat transfer mode at significant heat loads. An unexpected stepwise decrease in the instant heat transfer coefficient has been revealed in the course of crossing the vicinity of the critical temperature along the supercritical isobar. This means that the peaks of isobaric heat capacity and excess thermal conductivity, which are known from stationary measurements, do not affect the experimental results. It is assumed that the action of considerable gradient in temperature and the presence of heat-transfer surface in pulse heated system can serve as factors that suppress large-scale fluctuations, leading to a “smoothing” the critical enhancement of the thermophysical properties. As an important consequence, this study gives new insight into selection of the operating pressure of supercritical heat transfer agent.