Gefei Wu

Thermal and rheological properties of carbon nanotube-in-oil dispersions

Prior work on asymmetric thermally conducting nanoparticle dispersions has shown that it is possible to raise the thermal conductivity of low thermal conductivity liquids at modest volume fractions of nanoparticles. Stable and reproducible nanotube dispersions require careful control of the dispersant chemistry as well as an understanding of their response to input energy. This paper addresses the effects of dispersant concentration, dispersing energy, and nanoparticle loading on thermal conductivity and steady shear viscosity of nanotube-in-oil dispersions. The thermal conductivity and viscosity of these dispersions correlate with each other and vary with the size of large scale agglomerates, or clustered nanoparticles, in the fluids. Fluids with large scale agglomerates have high thermal conductivities. Dispersion energy, applied by sonication, can decrease agglomerate size, but also breaks the nanotubes, decreasing both the thermal conductivity and viscosity of nanotube dispersions. Developing practica...

Integration of Nanofluids into Commercial Antifreeze Concentrates with ASTM D15 Corrosion Testing

Abstract : Originally five candidates of nano material were chosen for making stable nano dispersions. Nano graphite particles remain a practical choice for nanofluids thermal application after taking divergent performance attributes into full account: significant thermal conductivity increases, minimal viscosity increase, low density for better dispersion stability, and relatively low cost, among others. Three different types of commercial antifreeze coolants were chosen for the integration with graphite nano fluids. Without corrosion inhibitors our nano coolants typically fail both ASTM D15 engine coolant corrosion tests: D1384 and D4340. Yet, heating up and adding in electrolytes are two common ways to destroy a nano particle dispersion. After making adjustments in particle loading, choosing an effective dispersant, and establishing proper dispersant levels, two nano graphite coolants made from two different nano sources passed both engine coolant corrosion tests plus the CID AA-52624A compatibility and storage stability tests. Compared with the base fluid, the nano graphite coolants thermal conductivity has more than a 25% increase at 2 volume percent particle loading, which is a significant enhancement.