Forced convection heat transfer from confined circular/semi-circular heaters and coolers with various orientations

Abstract

The combined implementation of porous medium and hybrid nanofluid with heaters and coolers can be an effective technique to improve the efficiency of several types of electric equipment. In this regard, the present study has been conducted to analyze the forced convection heat transfer of ${\mathrm{Al}}_2{O}_3-\mathrm{CuO}$ water-based hybrid nanofluid in porous channel with pairs of heaters and coolers of various shapes. The circular and semi-circular heaters and coolers with distinct orientations are considered. The Peclet number $\left(25\le \mathrm{Pe}\le 200\right)$, Darcy number $\left({10}^{-6}\le \mathrm{Da}\le {10}^{-1}\right)$, porosity $\left(0.1\le \epsilon \le 0.9\right)$, and volume fraction of hybrid nanoparticles $\left(0.02\le \varphi \le 0.08\right)$ are chosen as the governing parameters. The governing equations are solved by using the finite element method based commercial software COMSOL Multiphysics. The acquired results exhibit that the heat transfer from heaters and coolers is enhanced by decreasing $\epsilon$ and $\mathrm{Da}$ for all the cases and values of $\mathrm{Pe}$ and $\varphi$. The lowest heat transfer has been obtained by circular heaters and coolers (case 1). Moreover, the semi-circular heaters and coolers with curved facing towards channel inlet (case 2) and flat surface towards the bottom channel wall (case 4) show higher heat transfer compared to other cases. The average Nusselt number for case 4 is around 3.63% higher from case 2 at the highest values of the considered parameters. Case 4 shows the minimum drag coefficient and maximum heat transfer at the highest values of the governing parameters.