Surface Coating, Dropwise Condensation, Heat Transfer Coefficient, Horizontal Tube, Nanotechnology
In this work, an amorphous silica nanospring (SN) coating is considered as a method to induce hydrophobicity and dropwise condensation on aluminum tubes for both water and methanol. Silica nanosprings offer several advantages over other one-dimensional nanostructures including high surface area (350 m2 g-1), mild growth conditions (350°C, atmospheric pressure), and thermal stability (< 1000°C in air). Special focus in this work will be given to baseline testing and the performance of functionalized SN tubes. Testing to investigate the performance of SN-coated tubes and compare against the performance of uncoated tubing will be conducted in a purpose-built environmental chamber. In order to increase the amount of heat transfer possible within this chamber, 3D-printed fluid-carrying manifolds were designed to significantly increase the amount of available tube surface area. Two different methods of calculating condensation heat transfer coefficients from collected data are compared. Additionally, the existence of an ideal SN coating thickness for maximizing heat transfer and condensation rate is investigated. Future work will focus on using the printed and optimized manifolds to collect data from both a set of uncoated and sets of SN-coated tubes.