| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1740768 | Progress in Nuclear Energy | 2014 | 6 Pages |
•The flow and heat transfer in U-tubes of steam generator are investigated with CFD.•The curve of the total pressure drop with mass flow rate is obtained.•In the curve there exists the negative slope used to judge where the flow instability occurs.•The inlet subcooling and U-tube length have large influence on the reverse flow.
It is known that the parallel flow in inverted U-tubes of steam generator (SG) may occur the non-uniform or unstable flow under the natural circulation condition. Though the unstable flow phenomena in the SG are thought as the Ledinegg-type flow excursion that is dominated by the flow resistance and gravitation pressure drop, it has not been studied well. In the present work, the U-tubes in the SG are divided into three groups by their length, and the flow behavior of single phase water in the U-tubes is investigated with CFD method. The curves of total pressure drop with mass flow rate are obtained. The influences of the inlet subcooling and U-tube length on the flow stability are discussed. It is found that when the total pressure drop of parallel U-tubes is given, the higher the inlet subcooling is, the more easily the reverse flow occurs. As the inlet subcooling is low, the reverse flow occurs more easily in U-tubes with the shorter length. However as the inlet subcooling is high, the reverse flow occurs more easily in U-tubes with the longer length.
