Nanoengineered Surfaces for Thermal Energy Conversion

Abstract

Abstract.We provide an overview of the impact of using nanostructured surfaces to improve the performance of solar thermophotovoltaic (STPV) energy conversion and condensation systems. We demonstrated STPV system efficiencies of up to 3.2%, compared to ≤1% reported in the literature, made possible by nanophotonic engineering of the absorber and emitter. For condensation systems, we showed enhanced performance by using scalable superhydrophobic nanostructures via jumping-droplet condensation. Furthermore, we observed that these jumping droplets carry a residual charge which causes the droplets to repel each other mid-flight. Based on this finding of droplet residual charge, we demonstrated electric-field-enhanced condensation and jumping-droplet electrostatic energy harvesting.

Design of Lubricant Infused Surfaces

“…Condensation experiments were performed inside of a controlled environmental chamber. TFTS-functionalized CuO coatings were applied to the exterior surface of copper condenser tubes . The TFTS-coated CuO was infused with lubricant by first placing a few droplets of lubricant onto the surface and allowing them to spread completely, then using a nitrogen stream (99.9%, Airgas) to shear off excess lubricant.…”

“…TFTS-functionalized CuO coatings were applied to the exterior surface of copper condenser tubes. 56 The TFTS-coated CuO was infused with lubricant by first placing a few droplets of lubricant onto the surface and allowing them to spread completely, then using a nitrogen stream (99.9%, Airgas) to shear off excess lubricant. Following the addition of lubricant, the chamber was sealed and noncondensable gases were evacuated with a vacuum pump (except in the case of the ethanol lubricant, where the vacuum pump was not used so as not to evaporate the ethanol).…”