Comparison of Selected Heat-transfer Correlations for Supercritical Water Flowing Upward in Vertical Bare Tubes

Abstract

This paper presents an extensive study of selected heat-transfer correlations applicable to supercritical water flowing upward in vertical bare tubes. A comprehensive combined dataset was collected from 33 papers by 27 authors including more than 125 graphs within a wide range of parameters. These ranges are: pressures 22.5 - 34.5 MPa, inlet temperatures 85 - 350oC, mass fluxes 250 - 3400 kg/m2s, heat fluxes 75 - 5400 kW/m2 and tube lengths 0.6 - 27.4 m. This combined dataset was investigated and analyzed. Heat Transfer Coefficients (HTCs) and wall temperatures were calculated using several selected correlations and compared to the experimental data.Two of the most widely used correlations and a more recently developed one were chosen for this comparison: modified Bishop et al. correlation (1964), Swenson et al. correlation (1965) and Mokry et al. correlation (2009). The main objective of the study was to find the best correlation for supercritical water heat transfer in bare tubes, which might also be used for preliminary calculations of fuel bundles as a conservative approach. The examined correlations are intended for normal and improved heattransfer regimes.The comparison shows that the Bishop et al. correlation deviates quite significantly from the experimental data within some flow conditions. On the other hand, the Swenson et al. and Mokry et al. correlations show a significantly better fit within most of the examined operating conditions.