Role of Hierarchically Structured Surfaces in Boiling Critical Heat Flux Enhancement

We report large enhancements in critical heat flux (CHF) on hierarchically-structured surfaces, fabricated using electrophoretic deposition of silica nanoparticles on microstructured silicon and electroplated copper microstructures covered with copper oxide (CuO) nanostructures. A critical heat flux of ≈250 W/cm2 was achieved on the CuO hierarchical surface and good agreement between the model proposed in our recent study and the current data was found. These results support the idea that roughness-amplified surface forces are responsible for CHF enhancement on structured surfaces. This high heat removal capability promises an exciting opportunity for new surface designs for high flux thermal management.