Visual investigation on the boiling crisis post the flow instability in the channel with bypass

• Published in: Annals of nuclear energy 2019-09, Vol.131, p.171-184
• Main Authors: Lu, Qi, Liu, Yu, Huang, Huijian, Shen, Caifen, He, Hangxing, Zhou, Linglan, Chen, Deqi
• Format: Article
• Language: English
• Subjects: Boiling crisis; Channel with bypass; Flow instability; Two-phase interface morphology; Visual experiment
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2019.03.036

•A visual experiment was conducted for the boiling crisis post the flow instability in the channel with bypass.•The trigger mechanism of boiling crisis was analyzed based on the flow state and the two-phase interface morphology.•A CHF model appropriate for the test-sections with different inner diameters was proposed. In this study, a visual experiment was conducted in the channel with bypass for the boiling crisis post the flow instability. Also, the trigger mechanism of boiling crisis was researched combined with the flow state and the two-phase interface morphology. Meanwhile, all the boiling crisis occurred in this study belonged to DO (Dry Out) type boiling crisis. As for the high liquid mass fluxes (Gl = 1500 kg/m2s, Gl = 2000 kg/m2s) and the large inlet subcoolings (Tsub = 40 K, Tsub = 30 K) in the channel of Din = 2.15 mm, the liquid film near the heating wall was rapidly broken up due to the intense evaporation of itself and the significant dragging of vapor core, which lead to the simultaneously occurrence of the flow instability and the boiling crisis. As for other working conditions, the boiling crisis subsequently occurred with the heat flux further increasing as the flow instability happened. Finally, a CHF model was established based on Confinement number (Nconf), Subcooling number (Nsub), Weber number (We) and the geometric structure characteristics of test-section (Lh/Din) with all the errors less than ±25%.