Pool Boiling Studies on Nano-Structured Surfaces
The effect of nano-structures on pool boiling heat transfer is explored in this study. The silicon nano-structures are fabricated on 4″ double-side polished silicon wafers using Step and Flash Imprint Lithography (SFIL) process. An array of “nano-fins” consisting of 200 nm diameter pillars of 100 nm height, lateral pitch of 1 μm and transverse pitch of 0.9 μm are created in a rectangular pattern on the wafer surface. The test surface is used for pool boiling experiments using PF-5060 as the test fluid (Manufacturer - 3M Co., boiling point - 56 °C). Experiments are performed under saturation and liquid sub-cooling conditions. The heat flux measurements on the nanostructures are compared with that of bare surfaces. The test rig is of constant heat flux type. Results are reported at the maximum heat flux point. The nano-structured test surface showed a 41% increase in heat flux compared to the bare test surface under the saturation test condition. The 10-degree sub-cooling and 20-degree sub-cooling test conditions showed a 19% and 27% enhancement at the maximum heat flux point respectively.