Convection heat transfer of alkali liquid metals and LBE in hexagonal bundles of uniformly heated tubes with helical spacers | Academic Article individual record

© 2018 High temperature heat exchangers for solar thermal power and alkali liquid metals and lead–bismuth eutectic (LBE) cooled small modular nuclear reactors (SMRs) employ bundles of heated tubes or fuel rods with and without helical spacers for enhancing convection heat transfer. However, applicable Nusselt number correlations are not available and the reported data is relatively scarce. This work reviews, compiles, and correlates the reported experimental data and numerical analysis results for convection heat transfer of sodium, sodium–potassium (NaK) alloys, and lead–bismuth eutectic (LBE) in hexagonal bundles of uniformly heated tubes with helical wire-wrap and finned spacers. The compiled experimental data of fully developed Nusselt number for NaK alloys and LBE is for bundles of 19 and 37 uniformly heated tubes with pitch-to-diameter ratio (P/D) = 1.053–1.2824. It includes 103 Nusselt number values for a wide range of Peclet number (Pe) (9–2560). In addition, the compiled database includes 42 numerical Nusselt number values for liquid sodium and LBE at Pe = 30–1070 in bundles of 7–217 uniformly heated tubes with P/D = 1.194–1.31. The complied database for the bundle average Nusselt Number, Nub,ww, and the Nusselt number in central subchannels, Nuww, is correlated, respectively, as: Nub,ww=[4.387+0.00878(P/D)20.6]+[0.0306-1.647×10-4(P/D)14.03]Pe0.85 Nuww=1.515[4.387+0.00878(P/D)20.6]+1.364[0.0306-1.647×10-4(P/D)14.03]Pe0.85 Both correlations agree with the majority of the compiled experimental and numerical data to within ±15%. Nuww is consistently lower than Nub,ww, and the difference is independent of P/D, but increases from 38% at low Pe (<100) to as much as 52% at Pe = 1100. Nuww, is also higher than that reported earlier by the authors for bare heated tubes, Nus, with the difference increasing from 42% to 111% with increased Pe from 300 to 1100, and decreased P/D from 1.3 to 1.1.

author list (cited authors)
El-Genk, M. S., & Schriener, T. M.
publication date
Elsevier BV Publisher
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