This is an open access article distributed under the CC BY-NC-ND 4.0 terms and conditions.
Volume 13 article 334 pages: 235-240
The aim of this
experiment was to investigate convection heat transfer in the cooling processes
of Al2O3-water nanofluid in concentrations of 0.15%, 0.25% and 0.5% by volume,
respectively. The test section was a 1.25 m brass pipe with a 4.9 mm inner
diameter and outer pipe of 38.5 mm diameter of a counter flow double-pipe heat
exchanger. The temperatures at the nanofluid inlet in the inner pipe were a
constant 40oC, and 23oC for the water at the inlet of the outer pipe. The
results of this study indicated a more enhanced coefficient convective heat
transfer of the cooling process than that of the heating process. The new
equation of the Nusselt number obtained in the cooling process was Nunf=0.75Re 0.846
Pr -2.28 φ0.03 at particle volume concentrations of 0.15%, 0.25% and 0.5%. The maximum
ratio enhancement of the nanofluid heat transfer in the cooling process was
45.2% at a particle volume concentration of 0.25%, while for the heating process
nanofluid heat transfer was same as that for distilled water.
The authors would like to thank the Ministry of Higher
Education of Indonesia for the financial support.
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