Convective heat transfer and flow performance analysis for a non-homogeneous nanofluid in a circular minichannel

This study investigates convective laminar flow and heat transfer of alumina-water nanofluid inside a circular minichannel subjected to constant heat flux and wall temperature. The results of numerical studies on non-homogeneous two-component and single phase homogeneous methods revealed that the non-homogeneous model provides more accurate results, while homogeneous model highly underestimates the experimental data available in literature. The nanofluid showed higher performance and efficiency rates at lower Pe number, although decrease in particle size raised the friction factor and pressure drop. The comparison of numerical results between non-homogeneous and homogeneous methods, applying the Ryzhkov and Minakov thermophoresis coefficient [68] showed higher performance and efficiency rates compared to the McNab and Meisen thermophoresis coefficient [90]. The results on the effect of thermophoresis strength showed higher heat transfer coefficient, Nusselt number, and lower wall shear stress. The performance results show higher values at low Pe numbers. The results of numerical studies on non-homogeneous model presented higher performance compared to the base fluid with increasing the particle size and decreasing the Pe number. The results obtained via nanofluid properties dependent on additional parameters such as particle size and temperature have higher accuracy compared to applying only particle concentration dependent nanofluid properties. Further experimental and numerical studies on mechanisms of heat transfer, and thermophoresis effect in nanofluids are strongly recommended.