Adding small amounts of nanoparticles to thermal fluids is known to increase the thermal conductivity of the liquid substantially. Enhancements of the order of 30% to 40% can be achieved with as little particulate content as 10% by volume. The potential benefits of such enhancement are substantial: smaller size of heat transfer equipment, faster rate of heat exchange, and overall higher efficiency of energy utilization. Nanoparticle suspensions, more commonly referred to as nanofluids, have the potential to produce energy savings of several trillion BTU per year in the electric power industry, with a corresponding reduction of emissions in carbon dioxide, nitrogen and sulfur oxides. The ideal nanofluid should exhibit maximum heat transfer properties with minimal increase in viscosity and maximum stability of performance over repeated cycles of operation under shear and temperature swings. At present, there is no established theory by which such optimization can be attempted. If the presence of clusters is in fact beneficial, as it is has been suggested, it is not known how their size, structure, or volume fraction affects their heat transfer rate or their flow properties.
The PIs will apply the tools of colloid engineering and computational material science to produce and study stable nanofluids with controlled degree of clustering. Nanoparticles will be surface treated with molecules of varying chain length and ionic character to produce a thin surface layer that protects particles against aggregation. The same technique will be used to produce stable nanoclusters of well-defined size. The formulated nanofluids will be used to test the prevailing theories for heat enhancement and in particular, to determine whether chain-like clusters could in fact enhance heat transfer by providing efficient pathways for the conduction of heat. Multiscale simulations will employ molecular dynamics, for atomistic-level detail, and dissipative particle dynamics, for mesoscale modeling, to study the effect of clustering on heat transfer.
The broader aim of this research project is directed towards enhanced energy utilization through the application of colloid science and state-of-the-art multiscale modeling with the ultimate goal to formulate commercial nanofluids. The collaboration between academia (Penn State) and industry (Advanced Cooling Technologies) will provide the graduate and undergraduate students in this program with the opportunity to contribute to research that is both fundamental and industrially relevant. The interdisciplinary character of the proposed research and the integration of science and technology, both at the experimental and computational levels, are particularly suited for a presentation to a wider audience. The PIs will produce a computer animation based on atomistic simulations, to demonstrate heat transfer through nanoparticles nanocluster and serve a demonstration module for elementary and middle-school students.
