Innovative Nanostructured Wicks for Heat Pipes

A good wicking structure is necessary for the design of a highly efficient heat pipe. Several unique aluminum oxide nanostructures were developed as wicks for heat pipes. The wicks were manufactured via an anodization process at various anodization voltages and etching times. This allows for the manufacture of spatially variable wicking structures that can be tuned for specific applications. The resulting nanostructures were characterized with a scanning electron microscope. Six distinct wicking structures are shown in Fig. 1. The honeycomb nanostructure is a self-ordered, hexagonal columnar array. The clumped nanotube structure is composed of bundles of nanotubes separated by deep grooves. The teepee nanostructure has a honeycomb bottom covered with a conical structure top. The horizontal nanofiber structure consists of nanofibers laying parallel to the substrate surface. The ridge network nanostructure is a multiscaled structure with nanoporous ridges. The clumped nanofiber structure is formed from long tangled fibers that meet in a thin ridge. Each of these structures has features useful for nucleation, evaporation, and condensation. These wicks will have many applications in the fields of heat pipes and two-phase heat transfer.