Investigation of mixed convection heat transfer in a vertical duct for electronic obstacle surfaces employing TiO 2 -pure water nanofluid

In this work, the numerical investigation of mixed convection heat transfer and flow structures around four trapezoid obstacle geometries in a duct was carried out using TiO₂-pure water nanofluid and pure water. Geometries have a constant heat flux, and they were placed opposed each other on the parallel plates forming the duct, two on the left side and two on the right side. The numerical investigation was performed by solving the continuity, momentum, and energy equations in a steady, laminar, and two-dimensional flow using the academic Ansys-Fluent software. To direct the flow to the warmed trapezoid obstacle elements, flow director fins were placed on the upper inlet surfaces of the duct at angles of 30^o and 60^o. Except for the obstacle elements, all surfaces of the duct and the fins are adiabatic. The results of the work were compared with those from experimental and numerical studies in the literature. It was found that in the case of using TiO₂-pure water nanofluid in the 60^o fin angle duct at Ri* = 200 and Re = 200, the Nu_m number of the object on the upper left side is 8.22% higher than the one on the lower left side. In addition, it was found that the performance evaluation criterion number value achieved in the 60^o fin angle for Re = 200 and Ri* = 50 was 9.98% and 6.55% higher than that in the Re = 200 and Ri* = 200 when nanofluid and pure water were used, respectively.