A hybrid substrate for practical applications in dropwise condensation enhancement

We introduce a durable hybrid substrate consisting of superhydrophilic micropillars surrounded by superhydrophobic depressions for practical industrial applications. The proposed surface can be mass-produced via a facile and affordable method. Moreover, the stability tests show that the wettability properties of fabricated surfaces do not vary after the imposition of hot steam flow for 110 h. Two hybrid samples with different patterns of micropillars are compared with superhydrophobic and bare aluminum samples to explore the physics behind the condensation improvement ability of hybrid surfaces. The results reveal that the heat transfer coefficient and heat flux can be significantly increased with the incorporation of micropillars with optimized dimensions. Among the tested surfaces, the hybrid one, whose pillar's diameters are 500 μm, increases the heat transfer coefficient by 33.50% and 19.60% with respect to the superhydrophobic and bare surfaces, respectively, at a subcooling temperature of 18.50 °C.