2017 Volume 43 Issue 2 Pages 95-102
Substantial heat transfer enhancement is possible using a passage filled with a nanofluid-saturated metal foam, because of its high specific surface area, high thermal conductivity and comparatively low pressure drop. In addition to the Brownian diffusion and thermophoresis associated with nanofluids, both thermal dispersion and particle mechanical dispersion must also be fully understood in order to elucidate their combined effects on the heat transfer enhancement mechanism. Microscopic numerical calculations were conducted using a numerical model describing a structural unit of a passage filled with nanofluid-saturated metal foam. The results were integrated over a local control volume to evaluate the mechanical dispersion terms purely from the theoretical basis. The present study revealed that particle volume fraction has a limited effect on the thermal dispersion correlation, so that the correlations obtained for the base fluid are universally applicable. On the other hand, the nanoparticle mass flux was found to be sensitive to the interstitial heat transfer rate from the metal to nanofluid, since it increases with the interstitial heat transfer rate.
