The University of Tokyo · Engineering
Professor Kai Wang's research lab specializes in thermal hydraulics, boiling heat transfer, and nuclear reactor safety, with a strong focus on critical heat flux (CHF) mechanisms in nucleate and flow boiling under various conditions. The lab investigates material effects on CHF, surface wettability, roughness, and thermal effusivity, particularly in reactor components such as debris beds and in-vessel retention systems for sodium-cooled fast reactors. Advanced experimental techniques, including high-speed imaging and 3D facial scanning for non-intrusive data analysis, are employed to study bubble dynamics and surface evolution. The lab also develops predictive models and numerical simulations for coastal ocean circulation and reactor safety systems.
Figures are computed from collected data and may differ slightly.
This study conducts a critical heat flux (CHF) experiment on a carbon steel block, and the block is positioned on slope that is declined at angles of 5° and 10°. The results of the carbon steel block experiment were then analyzed and compared with the results obtained from a copper block experiment that had been conducted previously at the same test facility. The comparison showed that several different types of phenomena had occurred, and the carbon steel block CHF at both 5° and 10° was much l
In this study, experiments of downward-facing flow boiling were conducted to investigate material effects on CHF. Experiments were conducted using aluminum, copper, and carbon steel. It was found that different materials had different CHFs. Aluminum has the biggest CHF while copper has the lowest CHF for each mass flux. After experiment, surface wettability increased and surface became rougher, which was probably due to the oxidation process during nucleate boiling. The CHF difference is likely
Based on the idea of Lagrangian time-average residual current, a coastal water circulation model which can describe the circulation in a coastal water-shelf s ea system where tidal currents and some quasi-steady flows, such as the Kuroshi o in the East China Sea, are of the same order and dominant in the observable fl ow field, is developed. In this paper, the summer circulations in the Bohai, Yel low and East China Seas are diagnostically simulated by a sigma coordinate semi -implicit numerical
Due to the important role critical heat flux (CHF) plays in the boiling field, it is of great significance to study CHF, especially the mechanism of CHF in the nucleate boiling. In this study, a new model to predict CHF both in pool boiling and flow boiling of downward-face was proposed and the relationship between CHF and nucleation site density (NSD) was studied. The model was based on the bubble interaction theory, which assumed that CHF happened due to the coalescing of the bubbles generated
For the Japan Sodium-cooled Fast Reactor (JSFR), should the hypothesized core disruptive accident (CDA) happened, the in-vessel retention (IVR) will be the main target to achieve. In the heat-removal phase of the CDA, the debris bed will be piled up on the debris catcher. The capability of stable cooling and avoiding recriticality on the debris bed will be the main issues for achieving IVR. Previous studies have shown that the homogeneous debris bed can attain stable cooling and eliminate the pr
Facial landmarking locates the key facial feature points on facial data, which provides not only information on semantic facial structures, but also prior knowledge for other types of facial analysis. However, most of the existing works still focus on the 2D facial image which is quite sensitive to the lighting condition changes. In order to address this limitation, this paper proposed a coarse-to-fine method only based on the 3D facial scan data extracted from professional equipment to automati
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