The flow of alumina-water nanofluid across heated circular tubes arranged in inline and staggered arrays in a heat exchanger has been studied. The thermophysical properties of the nanofluid are determined using Corcione correlations, which are based on several experiments. The nanoparticle diameter dp is between 10 and 50 nm, with particle volume fraction ϕ varying from 0.01 to 0.05 and Reynolds number Re ranging from 10 to 200. Heat transfer augmentation takes place when nanoparticle concentration is increased. Mean Nusselt number NuM is increased by 31% when ϕ is increased from 0.01 to 0.05 at Re = 200 and dp = 10 nm in an inline array and by 25% in a staggered array. The use of smaller nanoparticles significantly promotes the thermal performance of the heat exchange arrays; NuM is enhanced by 20% for the inline array and by 16% for the staggering array when dp decreases from 50 nm to 10 nm at Re = 200 and ϕ = 0.05. NuM of the staggering array of cylinders at Re = 200, dp = 10 nm and ϕ = 0.05 is 60% greater than NuM of an inline array of cylinders. Finally, correlations are derived for the calculation of NuM of inline as well as staggered arrays.

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