Nanorefrigerants are produced by dispersion of nanometer sized (1-100 nm) solid particles having high thermal conductivity such as Cu, Al2O3, ZnO, CuO, etc. in a refrigerant and used in engineering devices to enhance the heat transfer capabilities. They are used in numerous applications such as tribology, chemistry, environmental areas, surfactants and coating, pharmaceutical and medical applications, microprocessors, jacket water cooling in vehicles and fuel cells. In this study, forced convection fluid flow and heat transfer characteristics of R600a/Al2O3 nanorefrigerant have been investigated numerically. Three different nanoparticle volume fractions (0.8, 2.0 and 4.0%) were used in numerical calculations. Numerical study has been implemented under three-dimensional steady-state laminar flow condition. The circular cross-sectioned duct geometry with uniform surface heat flux has been used as computational domain. The effect of nanorefrigerant and nanoparticle volume fraction on the average convective heat transfer coefficient and average Darcy friction factor have been analyzed in detail. The velocity and temperature distributions inside the duct were obtained for different nanoparticle volume fractions and Reynolds numbers. Variation of local heat transfer coefficient and local Darcy friction factor along the duct length have also been investigated. It is seen that increasing nanoparticle volume fraction increases the convective heat transfer in the duct. However, pressure drop are not affected by the change of nanoparticle volume fraction.
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