Specifics of forced-convection heat transfer to supercritical water flowing upward in annular and bundle flow geometries

Abstract

Since annulus- and bundle-flow geometries impede coolant flow, heat transfer to the coolant would occur differently than in bare tubes. The main objective of this work is to propose and verity a universal method to accurately predict Heat Transfer Coefficients (HTCs) and wall temperatures using HTC correlation(s) for various annular- and bundle-flow geometries cooled with upward flow of SCW. The bare tube correlation proposed by Jackson (2002) [3] predicted heat transfer within experimental uncertainties for most trials and, to some extent, followed wall temperature trends in regions of Deteriorated Heat Transfer (DHT). However, it was found that, in general, most bare tube HTC correlations could not be used beyond onset of DHT in bare tubes. Furthermore, analysis of the experimental data showed that the heat flux at which DHT appears in bare tubes is significantly lower (up to three times) than in single-rod and 3-rd bundle channels.