On the Choice of Corresponding Pressures in a Novel Fluid-to-Fluid Similarity Theory for Heat Transfer at Supercritical Pressure

A novel fluid-to-fluid similarity theory, developed in the past years and recently refined and better assessed, allows for achieving an appropriate scaling of heat transfer phenomena at supercritical pressures with different fluid systems. The theory is a sound contribution to define dimensionless groups constituting the boundary conditions to be imposed in designing similar heat transfer experiments for different fluids at supercritical pressure. This achievement is of great importance for broadening the basis of available data in view of the design of the supercritical water-cooled reactors (SCWRs). Previous publications and forthcoming papers describe different details of the similarity theory, showing its success in front of CFD analyses made by DNS, LES and RANS calculations. The aspect dealt with in the present paper relates to the choice of the most appropriate pressure for the different fluids, a necessary step to be performed, conditioning the accuracy of the obtained similarity in the selected operating conditions. Recipes were suggested in previous works for achieving this result, but a systematic analysis of their consequences and their relation to the classical choices dictated by the corresponding state theory was not yet performed in detail. This analysis is proposed in the present paper, better clarifying the issue in view of future refinements of the rationale at the basis of the similarity theory.