Boiling Heat Transfer on Superhydrophilic, Superhydrophobic, and Superbiphilic Surfaces

TL;DR

This study investigates how different wettability surfaces, especially biphilic and superbiphilic, enhance pool boiling heat transfer, revealing that combining hydrophilic and hydrophobic regions significantly improves heat transfer performance.

Contribution

It introduces the first superbiphilic surfaces, demonstrating their superior boiling heat transfer capabilities and providing an analytical model for their effectiveness.

Findings

Biphilic surfaces achieve higher heat transfer coefficients than uniform wettability surfaces.

Superbiphilic surfaces exhibit critical heat fluxes over 100 W/cm2.

Enhanced heat transfer performance with superbiphilic surfaces surpasses previous benchmarks.

Abstract

With recent advances in micro- and nanofabrication, superhydrophilic and superhydrophobic surfaces have been developed. The statics and dynamics of fluids on these surfaces have been well characterized. However, few investigations have been made into the potential of these surfaces to control and enhance other transport phenomena. In this article, we characterize pool boiling on surfaces with wettabilities varied from superhydrophobic to superhydrophilic, and provide nucleation measurements. The most interesting result of our measurements is that the largest heat transfer coefficients are reached not on surfaces with spatially uniform wettability, but on biphilic surfaces, which juxtapose hydrophilic and hydrophobic regions. We develop an analytical model that describes how biphilic surfaces effectively manage the vapor and liquid transport, delaying critical heat flux and maximizing the heat transfer coefficient. Finally, we manufacture and test the first superbiphilic surfaces (juxtaposing superhydrophobic and superhydrophilic regions), which show exceptional performance in pool boiling, combining high critical heat fluxes over 100 W/cm2 with very high heat transfer coefficients, over 100 kW/m2K.