Design, fabrication, and optimization of superbiphilic-pillar structures for extreme efficient boiling

Abstract

Boiling enhancement of engineering surfaces has important applications in energy systems and effective thermal management. This study developed the superbiphilic-pillar structures to maximize boiling efficiency. By utilizing micro-manufacturing methods and subsequent chemical modifications, superbiphilic-pillar specimen possesses both superhydrophobic pyramid-pillar and superhydrophilic channel were successfully fabricated. The developed superbiphilic-pillar structures can enhance the bubble nucleation through superhydrophobic pyramid-pillar, and achieve rapid detachment and effective coolant supply using superhydrophilic channel. The innovative structure and wettability design makes the superbiphilic-pillar specimen show an ultra-high heat transfer coefficient of 123.3 kW/m2K in the pool boiling test, and reach an excellent critical heat flux of 201.6 W/cm2, which is 216.2% and 97.1% higher than the flat specimen. To optimize the regional configuration, the effect of the proportion of superhydrophobic pyramid-pillar on boiling enhancement was studied. Combined with bubble dynamics analysis, it is shown that superhydrophobicity and pyramid-pillar structures have a competitive mechanism for the bubble coalescence and detachment. Thus, which leads to a non-monotonic relationship between boiling enhancement and the proportion of superhydrophobic pyramid-pillar, and the specimen with 56% superhydrophobic pyramid-pillar has the most efficient boiling performance.