Microchannel-elevated micromembrane for sustainable phase-separation condensation

A sustainable high heat transfer coefficient is critical for water and energy systems that utilize steam condensation. Current techniques cannot achieve a high heat transfer performance at a high heat flux. It is desired to separate vapor and liquid flow to provide a large surface area for condensation. Here, we report sustainable phase separation on microchannel-elevated micromembrane (MEM) by (1) separating the vapor and liquid using a hydrophobic micromembrane that rapidly removes condensed droplets to achieve a high heat transfer coefficient and (2) sustaining continual condensate removal inside the hydrophobic microchannels beneath the micromembrane to prevent flooding. We found that MEM could sustain phase separation at a heat flux of 1,000 kW/m2 without apparent failure. The heat transfer coefficient is 300% higher than that of the dropwise condensation on a hydrophobic flat surface. The phase separation on MEM provides a paradigm for sustainable high-performance condensation regardless of subcooling.