Paper 5: A Comparison of the Natural Convective Heat Transfer Performance of Three Fluids from a Horizontal Flat Surface near the Critical Point

Abstract

One of the main problems with heat transfer research in the critical region is the lack of accurate thermodynamic and transport property data. This lack of information makes the actual heat transfer performance very difficult to correlate, whilst the extreme property variations produce other effects, which are also dependent on the heating surface geometry. Three fluids, carbon dioxide, nitrous oxide, and chlorotrifluoromethane, were therefore tested with a view to establishing whether they had similar regions of heat transfer and whether any similarity with boiling existed. The results show that in the critical region the normal convective heat transfer is augmented by a process to give results which look very like the lower portion of the normal boiling curve. Finally the authors show evidence to support the theory that there are preferential areas of heat transfer in the supercritical region.