Numerical study of heat transfer and pressure drop of nanofluids in a combined porous media of hydrophobic and hydrophilic surfaces

Abstract

The present study provides a 3D numerical research on the hydro-thermal performance of water-Al2O3/CuO nanofluids and water/Al2O3-CuO hybrid nanofluid inside a U-bend tube incorporating a porous medium with both hydrophilic and hydrophobic surfaces. Furthermore, a single-phase flow is adopted to simulate the nanofluid flow. Taking into consideration the equation of the Darcy-Brinkman-Forchheimer, to simulate the flow of fluids in the porous media. The influence of Dean number on hydro-thermal performance in the range of (600–1750) was investigated. And according to the results, Dn = 600 had the best performance. Considering the outcomes, a completely hydrophobic wall has a better hydro-thermal performance than a completely hydrophilic one and other hydrophilicity and hydrophobicity combinations. As well, improvement in heat transfer efficiency is considerably influenced by the Darcy number (10−4–10−1) and the augmentation of the porous thickness ratio. Additionally, average Nusselt number and pressure losses for any and all types of nanofluids show an incremental schema with augmenting volume fraction, while PEC exhibits a reducing pattern. Besides this, structures with permeable porous media or ones with Da = 0.1 and rp = 0.6 present the highest PEC. Also, among the reviewed nanoparticles, Al2O3 with a volume percentage of 1% had the maximum PEC.