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Abstract
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In this work, the experimental heat transfer of metal oxide nanofluids in a plate heat exchanger was investigated.
For this purpose, Al2O3 20 and 40 nm?water, TiO2 10–15 and 25 nm?water, and SiO2 20–30 nm?water
nanofluids with 0.05, 0.1, and 0.2 wt%of nanoparticle concentration were used to investigate the increment of the heat
transfer coefficient for each nanofluid against distilled water. Nanofluid characterization was conducted by dynamic
light scattering analysis. Significant enhancements on the heat transfer coefficient in the present nanofluids were
observed. The results clearly show that increasing the nanofluid Reynolds number and concentration results in an
increase in their heat transfer coefficient. The maximum observed heat transfer enhancement for SiO2 was obtained
at 0.2 wt%and Reynolds number 37, which is 2.82. Furthermore, the minimum heat transfer enhancement for
Al2O3 (20 nm) was achieved at 0.1 wt%and Reynolds number 158 with 1.64. A new correlation was derived for
Nusselt number based on the experimental data of the mentioned nanofluids with an average relative error percentage
of 3.78%. Moreover, the variations of Nusselt number vs Peclet number, the overall heat transfer coefficient vs
Reynolds number, and the nanofluid friction factor vs Reynolds number were considered, and interesting results were
reported.
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