Heat transfer analysis at supercritical pressure using two layer theory

• Brief review of heat transfer to supercritical fluids is presented.
• Two separate model has been developed for finding out heat transfer coefficient and wall temperature based upon two layer theory.
• Both the models are able to take ‘heat transfer deterioration’ into account.
• Validation with experimental observation is also provided.

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.

Figure optionsDownload as PowerPoint slide