Numerical analysis of turbulent flow and heat transfer with nanofluid in elliptical cross-sectioned duct

In this study, varying major to minor axis ratio in an elliptic tube has been investigated numerically under the steady state, forced convection with turbulent heat flow conditions. Constant wall temperature was applied to tube wall. Mainly, hydrodynamically and thermally developed turbulent flow has been investigated. To obtain fully turbulent flow, study was performed Reynolds numbers between 10000 and 100000. Water was used as working fluid in the first part of study. ANSYS Fluent 17.0 tool was used for all simulations. After the end of numerical results, average Nusselt numbers and average friction factors were obtained and they were compared with correlations which are commonly used in the literature. Al2O3 / Water nanofluid was used as working fluid in the second part of study and all simulations were repeated. It is noticed that using of nanofluid increases average Nusselt number significantly. However, it leads to an increase in pressure drop inside the tube. As a result, it causes an increase in average friction factor. According to the results of the study, using of nanofluid increases average Nusselt number almost 13% in all models. At the same time, it causes an increase in average friction factor around 1.7%. It is noticed that different major to minor axis ratios have no significant effect on average Nusselt number and average friction factor. Also, correlations in the form of 𝑁𝑢=𝑎1 ×𝑅𝑒𝑏1 and 𝑓=𝑎2×𝑅𝑒𝑏2 are obtained for average Nusselt number and average friction factor in all models.