Progress on the development of new correlations under the framework of the IAEA Coordinated Research Programme on heat transfer in SCWR's

摘要

This paper begins with an introduction designed to provide researchers who are new to field of heat transfer to fluids at supercritical pressure with a brief picture of early developments, and to set the scene for the review of work on the development of new correlations for such fluids under the framework of the IAEA CRP. These are needed because of the active consideration now being given to water-cooled nuclear reactors operating at pressures above the critical value. Work on the development of a trans-critical look-up table aimed at covering the region near the critical point is outlined. A very large heat transfer databank has been compiled and subjected to a thorough screening process. It covers a wide range of conditions and has been used for the assessment of the performance of a number of empirical equations. A detailed error analysis was carried out for the most promising ones and an examination of parametric trends was made. A new correlation is described which has been specifically designed to combine simplicity of structure, explicit connection with physically-based phenomena whilst being able to cover both normal and deteriorated heat transfer conditions. It avoids direct dependence of heat transfer coefficient on wall temperature. The performance of this correlation was evaluated using the data set of Herkenrath et al for water at supercritical pressure. Results from a recent experimental study of heat transfer to carbon dioxide at supercritical pressure under conditions of mixed convection have been used to develop a set of equations to describe the general behaviour observed. Comparisons are made between the performance of a number of equations and the data from the carbon dioxide experiments and also some for water. Finally, the development is outlined of physically-based, semi-empirical models aimed at extending an empirical equation for variable property forced convection heat transfer to fluids at supercritical pressure to account for influences of buoyancy and flow acceleration.