Friday, October 5, 2012 - 11:00
1 hour (actually 50 minutes)
MRDC, Room 4211
Nanoengineered surfaces offer new possibilities to manipulate fluidic and thermal transport processes for a variety of applications including lab-on-a-chip, thermal management, and energy conversion systems. In particular, nanostructures on these surfaces can be harnessed to achieve superhydrophilicity and superhydrophobicity, as well as to control liquid spreading, droplet wetting, and bubble dynamics. In this talk, I will discuss fundamental studies of droplet and bubble behavior on nanoengineered surfaces, and the effect of such fluid-structure interactions on boiling and condensation heat transfer. Micro, nano, and hierarchical structured arrays were fabricated using various techniques to create superhydrophilic and superhydrophobic surfaces with unique transport properties. In pool boiling, a critical heat flux >200W/cm2 was achieved with a surface roughness of ~6. We developed a model that explains the role of surface roughness on critical heat flux enhancement, which shows good agreement with experiments. In dropwise condensation, we elucidated the importance of structure length scale and droplet nucleation density on achieving the desired droplet morphology for heat transfer enhancement. Accordingly, with functionalized copper oxide nanostructures, we demonstrated a 20% higher heat transfer coefficient compared to that of state-of-the-art dropwise condensing copper surfaces. These studies provide insights into the complex physical processes underlying fluid-nanostructure interactions. Furthermore, this work shows significant potential for the development and integration of nanoengineered surfaces to advance next generation thermal and energy systems.