الفهرس 
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Abstract
Nanofluids are suspensions of metallic or nonmetallic nano-powders in base liquid and can be employed to increasing heat transfer rate in various applications. In this work laminar flow forced convection heat transfer of (Al2O3 or CuO)/water nanofluid inside a circular tube with constant wall heat flux is investigated experimentally. The Nusselt numbers of nanofluids are obtained for different nano¬particle concentrations as well as various Reynolds number. Experimental results emphasize the enhancement of heat transfer due to the nano-particles presence in the fluid. Heat transfer coefficient increases by increasing the concentration of nano-particles in base fluid. The increase in heat transfer coefficient due to the presence of nano-particles is much higher than that obtained from single phase heat transfer correlation used with nanofluid properties. Considering the factors affecting the convective heat transfer coefficient of the nanofluid, a new convective heat transfer correlation for nanofluid under single-phase flows in tube is established. Comparison between the experimental data and the calculated results indicate that the obtained correlation describes correctly the energy transport of the nanofluid. The range of operating parameter is Reynolds number from 500 to 2500 and nano-particle volume concentrations up to 2.0%.