Analytical study on forced convection of nanofluids with viscous dissipation in microchannels

Hung Y.M., Heat Transfer Engineering 31, 1184–1192 , 2010

This paper presents an analytical study on the heat transfer characteristics of fully developed forced convection of nanofluids across a microchannel. Closed form solutions for the temperature distributions in the radial direction with the incorporation of viscous dissipation are obtained and the governing parameters include Brinkman number, thermal conductivity ratio, and nanoparticle volume fraction of the nanofluids. The effects of these parameters on the temperature distributions are investigated and analyzed for both heating and cooling processes. The heat transfer performance characterized by the Nusselt number is investigated based on the effects induced by these parameters. In the comparison between the models with and without viscous dissipation, it is found that the thermal performance of a microchannel is overrated when viscous dissipation is excluded in the analysis. It is concluded that these governing parameters are intimately interrelated in the flow and thermal analysis of nanofluids in microchannels. The interrelationship of the viscous dissipation effect and the nanoparticle volume fraction is examined in a contour deviation map of Nusselt numbers between the model with and without considering the viscous dissipation.

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