An improved wall boiling model for numerical simulation of subcooled flow boiling on a new hybrid micro/nanostructured surface

Abstract

Previous studies have demonstrated that micro/nanostructured surfaces have great potential for heat transfer enhancement. However, simulating subcooled flow boiling on such surfaces is difficult owing to the lack of proper bubble characteristic parameter models, because most models used in flow boiling simulations were developed based on smooth surface conditions, which may limit their applications in engineering design. In this study, we improved upon one validated bubble characteristic parameter model suitable for subcooled flow boiling on smooth surfaces to adapt to the new hybrid micro/nanostructured surfaces proposed by Huang et al. [“Experimental investigation of a new hybrid structured surface for subcooled flow boiling heat transfer enhancement,” Appl. Therm. Eng. 192, 116929 (2021)]. The new bubble characteristic parameter model incorporates both basic correction terms to account for boiling bubble behaviors and ad hoc parameters to account for other unknown effects. Through sensitivity analysis and detailed calibration, the model was simplified to a set of correlations and only one constant parameter. With this improved model, subcooled flow boiling heat transfer simulations were conducted for three target surface specifications under conditions of 4–10 MW/m2 incident heat flux and 1–5 m/s flow velocity and the related heat-transfer mechanisms were further compared and discussed. The maximum error between the simulation and experimental results remains less than 3.5%, indicating that the established model has considerable accuracy in predicting the heat transfer performance for this type of micro/nanostructured surface in high-heat-flux engineering design applications. The heat transfer enhancement for subcooled flow boiling on this type of hybrid micro/nanostructured surface is greatly beneficial owing to its proper organization of convection, evaporation, and quenching heat transfer.