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This project primarily focuses and uses one-step chemical reduction method for synthesizing copper nanofluids by reducing copper sulfate by sodium hypophosphite using microwave irradiation. Thermal conductivity of the product obtained is measured and the variation of thermal conductivity with pH and concentration of precursor is studied. Stability of the dispersion formed is studied by measuring zeta potential at different pH values. One-step method for synthesizing nanofluids has been used to produce nickel nanofluids and properties of the product formed were studied by transmission electron microscopy and x-ray diffraction techniques. High energy ball milling was used to produce copper nanoparticles to be used in the two step method for synthesizing copper nanofluids. The effect of milling time on the size of the crystallites formed was studied.

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The efficacy of a parabolic trough solar collector (PTSC) was improved by using TiO 2 /DI-H 2 O (De-Ionized water) nanofluid. Working samples consisting of nanofluids with concentrations of 0.05%, 0.1%, 0.2%, 0.3% and 0.5% were compared with deionized water (the base fluid) at different flow rates under turbulent flow regimes (2850 ˂Re ˂ 7440). The experiments were designed as per ASHRAE 93 (2010) standards. Heat transfer and the flow characteristics of nanofluids through the collector were studied, and empirical correlations were developed in terms of the Nusselt number, friction factor, and performance index. The convective heat transfer coefficient was improved up to 23.84% by using TiO 2 nanofluids instead of the base fluid. It was found that TiO 2 nanofluid with a volume fraction of 0.3% (at a mass flow rate of 0.0689 kg/s) will provide the maximum efficiency enhancement in the PTSC (9.66% higher than the water-based collector). Consequently, the absorbed energy parameter was found to be 10.3% greater than that of the base fluid.