Heat-Transfer Conditions for SuperCritical Water Within Pseudocritical Region in a Short Bare Tube

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Roman Popov
Mohammed Mahdi
K. Barati Far
M. Panszczyk
K. Grassby
Igor Pioro

Abstract

SuperCritical Water-cooled Reactor (SCWR) is the Generation-IV nuclear-reactor concept. The main advantage of NPPs with SCWRs is higher thermal efficiencies (43% - 55%). For safe and reliable operation of future SCWRs more experimental data are required in bundle flow geometries cooled with SCW. However, such experiments are extremely complicated and expensive. As a preliminary, but a universal approach is to use experiment data obtained in bare tubes with heated lengths and diameters similar to those of fuel bundles.

Current paper provides experimental data obtained in a short (0.6 m) vertical bare tube (ID 6.28 mm) cooled with upward flow of SCW. Analysis of this dataset is included. Main emphasis of this research is on SCW behaviour within the pseudocritical region, where all thermophysical properties undergo significant variations. Usually, three heat-transfer (HT) regimes are encountered at these conditions: 1) Normal HT, 2) Improved HT; and 3) Deteriorated HT. Conditions at which the DHT regime appears are also discussed.

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