Simultaneous Study Of Bubble Dynamics And Heat Transfer Coefficients In A Two-phase Flow 5×5 Rod Bundle
Abstract
Quantifying the relationship between the bubble dynamics and the two-phase heat transfer coefficients in rod bundles is essential for the safe operation of pressurized water reactors (PWRs) and small modular reactors (SMRs). In this work, the heat transfer coefficients and the bubble dynamics in a 5x5 rod bundles were measured simultaneously by an advanced heat transfer probe and a four-tip optical fiber probe using air–water system. The experiments were conducted at several superficial inlet gas and liquid velocities, corresponding to bubbly flow conditions, at eleven locations covering the wall regions, the subchannels and the gaps between the rods at three axial locations. The heat transfer coefficients were found to be significantly affected by the bubble rise velocity, the bubble passage frequency, and the void fraction, as these bubble dynamics determine the contact time between the eddies moved by the bubbles' movement and the surface of the heat transfer probe. The heat transfer coefficients were found to be 15–27 % higher at the downstream of the mixing vane spacer grids (MVSG) because of the effect of the MVSG on the bubble dynamics. The predictions of the heat transfer coefficients using the mechanistic model of [40] showed unsatisfactory agreement with the experimental data with an AARE between 19.26 % and 98.73 % at Jf = 0.3 m/s and between 13.9 % and 60.41 % at Jf = 1 m/s. The comprehensive data obtained in this work could be useful for the development of models for the prediction of the heat transfer coefficients based on the bubble dynamics in rod bundles.
Recommended Citation
S. Aldawood et al., "Simultaneous Study Of Bubble Dynamics And Heat Transfer Coefficients In A Two-phase Flow 5×5 Rod Bundle," Applied Thermal Engineering, vol. 269, article no. 126085, Elsevier, Jun 2025.
The definitive version is available at https://doi.org/10.1016/j.applthermaleng.2025.126085
Department(s)
Chemical and Biochemical Engineering
Keywords and Phrases
Bubble dynamics; Four-tip optical probe; Heat transfer probe; Rod bundles; Two-phase heat transfer
International Standard Serial Number (ISSN)
1359-4311
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2025 Elsevier, All rights reserved.
Publication Date
15 Jun 2025
Comments
Ministry of Education - Singapore, Grant None