With compact structure and enhanced heat transfer capacity, helical tube once through steam generators (HTSGs) are widely used in the small modular reactors. Nevertheless, the inside centrifugal forces make the flow more complicated, and increase the frictional pressure drop, which is closely related to the dual test of alternating thermal stress and flow instability. Therefore, the analysis of the friction factor in helically coiled tubes is significant to the efficient and safe operation of HTSGs.While the friction factor of single-phase flow in helically coiled tubes were fully studied and extensive correlations have been validated by a large amount of experimental data, the friction factor of two-phase flow is still lack of feasible prediction due to its much more complexity. The existed correlations of two-phase flow in helically coiled tubes are mostly based on specified experimental parameters, so the applicable range is limited. Few scholars have tried to extend these correlations to a broader applicability. The trivial applicable range is unsuitable for program development or engineering design, which needs an accurate prediction of frictional factor in a wider range.In this paper, the prediction of the existed correlations is evaluated by comparing the results with experimental data for friction pressure drop of two-phase flow in helically coiled tubes and the error under the operating conditions is derived. Since the known experimental data cannot cover a wide range of parameters, a method for predicting reasonable friction factor based on known correlations and subjective judgment is proposed. The accuracy of this method is also validated by the experimental data. The applicability of every friction factor correlation&nbsp;under operating parameters within D/d=15-100, P=0.1-6.3MPa and G=200-1500kg/m2s is determined through the proposed prediction method. Finally, a calculation model of friction factor suitable for a relatively larger range of operating parameters are established, which are sufficient to support the design and operation of steam generators and the development of the simulation programs.

Analysis of Friction Factor of Two-Phase Flow in Helically Coiled Tubes

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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