Heat transfer analysis at supercritical pressure using two layer theory

Supercritical fluids are gaining popularity mostly after introduction of supercritical power plants. Efficiency increment, elimination of dry out problem are some major advantages. But due to steep variations of thermophysical properties at supercritical pressure, heat transfer may 'enhance' or 'deteriorate' depending upon temperature range. Several correlations specific to supercritical pressure are available in the literature to deal with it but, are mostly unable to take deterioration into account. This study aims to analyze heat transfer phenomena at supercritical pressure. Two layer turbulent theory for heat transfer has been used to analyze the heat transfer phenomena with two separate models viz. wall function and thermal resistance analogy. Theoretical results were compared qualitatively and quantitatively for carbon dioxide and HCFC-22 and agreement was seems to be good at lower heat flux. Theory is able to take deterioration into account at higher heat flux but further work is needed to improve the reliability and accuracy of the theory. (C) 2015 Elsevier B.V. All rights reserved.