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Scalable Nanomanufacturing using Self-Assembled Biological Templates

Dry-Cooling Technologies using Phase Change Materials

Biotemplated Nanostructured Coatings for Enhanced Boiling and Evaporation

The Tobacco mosaic virus (TMV) is a rigid, rod-shaped plant virus defined by helical coat proteins wrapped around a single strand of RNA. It is an extremely stable bio-molecule measuring 300 nm in length and 18 nm in outer diameter, and can withstand temperatures up to 60 C and a pH range of 2 to 11. Through a novel genetic mutation, near-vertical assembly of the TMV onto various materials and conformal metalization can be achieved using a simple solution-based room-temperature fabrication technique. This provides a mechanism to develop simple, cheap, and scalable nanomanufacturing techniques for the realization of biotemplated surface-bound high surface area coatings. These nano-structured coatings can be used to enhance phase-change heat transfer processes, as well as the creation of nanoporous virus-structured membranes.

Transport and Separation through Virus-Structured Nanoporous Membranes

The TMV is a 300 nm long hollow cylindrical biomolecule with a 4 nm diameter central pore defined by 2130 helical coat proteins. The inner surface of the central pore is highly negatively charged, making it an ideal material for chemical and biological separations. The repeatable nanoscale pore size, along with its high surface charge, facilitates ion exclusion through the formation of overlapping electric double layers. Current research focuses on developing nanoporous membranes based on the TMV and experimentally investigating the transport and separation mechanisms for fluid flowing through the TMV protein channel.

Superhydrophobic surfaces repel water and resist wetting, leading to a large equilibrium contact angle and a small contact angle hysteresis. These surfaces provide a mechanism to realize efficient dropwise condensation, where microscale condensate droplets form into near perfect spheres. These spherical droplets are highly mobile and easily removed from the surface through a variety of mechanisms including coalescence-induced ejection.  This mobility inhibits the formation of an insulating liquid film, and therefore increases heat transfer rates. Ongoing research is focused on investigating and enhancing dropwise condensation using superhydrophobic surfaces with micro- and nano-scale structures with mixed surfaces wettability.

Biotemplated Superhydrophobic Surfaces for Enhanced Dropwise Condensation

This work is supported by:

The cooling of modern electric power plants accounts for over 40% of all fresh water withdrawals in the United States. Our research focuses on advanced dry-cooling technologies with the goal of eliminating the need for water altogether in these large-scale thermal systems. Specifically, the use of phase change materials (PCM) as an intermediate coolant is investigated as a means to transfer heat from the power plant condenser to the ambient air. The use of recirculating PCM flows, which undergo cyclical spray-freezing and slurry melting processes, has the potential to achieve this at low condenser temperatures and without the need for water. This work focuses on fundamental investigations of the spraying, freezing, transport, and melting of enhanced PCM materials.

Superhydrophilic nanostructured coatings can be used to enhance liquid-to-vapor phase change processes such as boiling and evaporation. By increasing the wettability of a surface and controlling the nature of the liquid-vapor-solid interface at the micro- and nano- scales, substantial increases in heat transfer can be achieved. Ongoing research in the Multiscale Thermofluidics Laboratory focuses on the use of virus-templated nanostructures to investigate the mechanisms of critical heat flux (CHF) and the enhancement of heat transfer coefficient (HTC) during nucleate pool boiling and flow boiling. Additional work focuses on studying and delaying the transition to film boiling during droplet evaporation and spray cooling using novel micro- and nano- structures.