The Effect of Nanoparticle Agglomeration on Enhanced Nanofluidic Thermal Conductivity

Abstract

The study and understanding of the enhanced thermal conductivity of nanofluids is a relatively young and growing research area. Thus far sample characterization at this scale, especially for in situ properties, has been incomplete and not well defined. Without adequate sample description capabilities, progress in understanding and ultimately realizing the full potential of enhanced nanofluidic thermal conductivity will be hampered. Presented here are thermal conductivity measurements, using the transient hot wire method, of samples prepared by systematic variation of both ultrasonication time and pH for alumina nanoparticle solutions. A marked shift in enhanced thermal conductivity relative to the carrier fluid alone is observed. The working hypothesis that the prevention of particle agglomeration leads to improved thermal conductivity is supported by in situ effective particle size distribution measurements using dynamic light scattering methods.