Porous and Wettability-Controlled Microstructures for Enhanced Heat Transfer Coefficient in Pool Boiling

Microstructures on boiling surfaces had been adopted to study heat transfer enhancement mechanism because of its controllability of precise geometries by MEMS techniques. In addition, several bubble-inducing surfaces such as porous or hydrophobic surfaces were verified to be combined with microstructures for further enhancement of cooling efficiency. In this research, microstructures with porous and dual-wettability (Janus) were fabricated by soft-lithography with replicating molds. In saturated pool boiling at atmospheric pressure, the porous and Janus microstructures increased the heat transfer coefficient by 50% over that of plain-cylindrical microstructures. The increase occurred because the porous and wettability-controlled structures favored vigorous bubble generation, and supported high contact line density, which is strongly related to effective cooling through the near-bubble region.