Abstract
There have been relatively few publications detailing correlations for heat-transfer in SuperCritical Water (SCW) flowing inside bundle geometry compared to SCW heat-transfer in bare-tubes. Since flow geometry is impeded by bundle geometry, heat-transfer to the coolant occurs differently in bundles than in bare tubes. In this paper, results of heat-transfer to supercritical water flowing upward in a vertical 1-rod annular channel and 3-rod bundle (rods are equipped with helical ribs) are discussed. The data obtained in this study could be applicable for a reference estimation of heat transfer in future designs of fuel bundles. The Jackson (2002) bare-tube heat-transfer correlation most accurately predicted Heat Transfer Coefficients (HTCs) in annular channel trials at heat fluxes less than 2.5 MW/m2. However, this correlation (along with others) did not predict HTCs accurately in annular channel trials at heat fluxes above 2.5 MW/m2 and in 3-rod bundle geometry at all values of heat flux tested. Changes in thermophysical properties of a coolant, especially, within the pseudocritical region, caused discontinuity in the calculated HTC profiles in most correlations.
