Nanoscale study on the effect of random roughness and wettability of alloy surface on boiling performance

DY Gao and ZY Sun and JY Han and ZW Liu and W He and CR Zhao and HL Bo, CASE STUDIES IN THERMAL ENGINEERING, 75, 107001 (2025).

DOI: 10.1016/j.csite.2025.107001

Boiling is widely observed in industrial applications such as nuclear power plants, where high heat transfer efficiency is required. Therefore, in-depth investigations of bubble nucleation at microscale and its impact on heat transfer remain essential. This study focuses on the boiling phenomena occurring in the steam generator tubes of pressurized water reactor (PWR). Molecular dynamics (MD) simulations are employed to investigate the phase change and heat transfer characteristics of water on nickel-based alloy surfaces with random rough structures. Based on experimental data, the effects of surface roughness on thermal performance are examined across a contact angle range of 60 degrees-90 degrees. The results reveal that wettability and surface roughness synergistically enhance bubble inception and heat transfer performance. Compared with the B = 90 degrees, 6 = 0 & Aring; surface, the B = 60 degrees, 6 = 5 & Aring; surface exhibits a 59.7 % earlier bubble inception time and a 39.9 % reduction in interfacial thermal resistance. The instantaneous maximum heat flux qmax is increased by 135.6 %. Notably, these two surface properties exhibit different degrees of influence on various key parameters. Roughness more effectively promotes bubble inception under poor wettability (B = 90 degrees), primarily through synergistic effects of enlarged contact area and reduced phase-change barriers. In contrast, the additional contact area resulting from increased roughness more effectively amplifies interfacial heat transfer on more hydrophilic surfaces (B = 60 degrees), leading to a substantial improvement in maximum heat flux qmax.

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