Hierarchically structured surfaces for 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 a CuO hierarchical surface with a roughness factor of 13.3, and good agreement between the model proposed in our recent study and the current data was found. These results highlight the important role of roughness using structures at multiple length scales for CHF enhancement. This high heat removal capability promises an opportunity for high flux thermal management.