Date of Award

1-1-2008

Degree Name

Master of Science

Department

Mechanical Engineering

First Advisor

Nsofor, Emmanuel

Abstract

The study on the modeling of energy transport in nanofluids divided the heat transfer in nanofluids into two portions - heat transferred by stationary particles and heat transferred by moving particles. Each portion was studied individually and then together. An equation for the thermal conductivity of nanofluids was developed based on the nanolayer thickness, Brownian motion and the size distribution of the nanoparticles. The expression developed successfully explained the enhanced thermal conductivity of nanofluids and led to some important conclusions. It was found that in this study Kinetic theory is not enough to explain the enhanced thermal conductivity of nanofluids. The contribution of Brownian motion of nanoparticles to the overall thermal conductivity of nanofluids was found to be very small. The study investigated the size distribution of nanoparticles which has been suggested to be an important factor and it gave satisfactory results. The Values of the thermal conductivity for different nanofluid combinations were calculated using the expression developed from this study and they agreed with published experimental data. The present model was tested against several nanofluid combinations. So far no study has reported the results of these many kinds of nanofluid combinations. To understand the properties that influence the thermal conductivity of nanofluids, parametric studies of a number of nanofluids were carried out. From the study, it was observed that Brownian motion is significant only when the particle diameter is less than 10 nm. So, this advanced technology of suspending nanoparticles in base fluids might provide answers to improved thermal management. Improved understanding of complex nanofluids will have an even broader impact.

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