Numerical approach to the suppression of film boiling on hot-spots by radial control of patterned wettability

This paper proposes a novel method for controlling the boiling phenomena of a thermally heterogeneous field on a surface. To achieve thermal heterogeneity, we used a heat flux gradient. The control method is based on radial pitch control of the patterned wettability using hydrophobic dots. The area fraction of the hydrophobic dots was set to be small near the center of the hot-spot and large in the marginal region. Consequently, the boiling phenomena at the center changed from a film boiling regime to a nucleate boiling regime. Compared with an uncontrolled surface, the critical heat flux was enhanced at the center region, and the heat transfer rate was enhanced at the marginal region. Pitch control prevents film generation at the center and film propagation over the whole surface, thus enhancing the overall critical heat flux of the whole surface.