Normal and deteriorated heat transfer upon heating of turbulent flows of heat carriers with variable physical properties in tubes

摘要

A short survey of the available knowledge on heat transfer of gaseous heat carriers with variable physical properties (gases and their mixtures, in particular, those catalytically reacting on a wall, high pressure vapor, as well as single-phase supercritical pressure heat carriers) to turbulent flows upon intense heating in tubes is presented. The problem of heat transfer deterioration under high heat loads (in particular, in the context of flow laminarization) is discussed. The existing knowledge about the nature of these phenomena and methods for their prediction are considered. The empirical relationships for estimating the temperature regime of the wall under conditions of normal and deteriorated heat transfer are presented. The consequences of the transition to new standards in properties of supercritical pressure heat carriers are shown from the viewpoint of accuracy in the engineering analysis of heat transfer by the existing methods. Ways of rehabilitation for old empirical formulas are proposed for the case of using new standards of thermophysical properties.