Heat transfer and hydraulic resistance of supercritical-pressure coolants. Part I: Specifics of thermophysical properties of supercritical pressure fluids and turbulent heat transfer under heating conditions in round tubes (state of the art)

The specifics of the thermophysical properties of single-phase supercritical pressure (SCP) coolants and the typical ranges of their thermodynamic state that determine the peculiarities of their turbulent heat transfer are considered. An assessment of the effect that dissolved gases with low critical parameters have on water and carbon dioxide properties is given. A brief analysis is presented of experimental studies on heat transfer of turbulent flows of SCP fluids in tubes when heating. Specific features of typical heat transfer modes (normal, deteriorated, and improved) are pointed out. The existing concepts concerning the nature of heat transfer deterioration are discussed. A simple classification of heat transfer regimes under high heat loads is proposed, which makes it possible to determine the reasons for and assess the degree of danger of heat transfer deterioration