Fe3O4-Water Nanofluid Free Convection within an Inclined 2D Rectangular Enclosure Heated by Solar Energy Using Finned Absorber Plate

Rached Nciri,Faouzi Nasri,Chaouki Ali,Yahya Ali Rothan

doi:10.3390/app11020486

Abstract

This work investigates a hydrodynamic problem involving the Fe3O4-Water nanofluid. The novelty of this investigation lies in the fact that the nanofluid free convection is evaluated within a specific rectangular enclosure having a finned absorber plate as the top wall, heated by solar energy. The fins below the absorber plate permit to enhance heat transfer towards the nanofluid. A numerical simulation is carried out in order to predict the influence of Rayleigh number, nanofluid layer position, enclosure inclination angle, and absorber plate fins height on the nanofluid flow (in terms of streamlines and velocity magnitude) and heat transfer (in terms of temperature and Nusselt number divided by a certain thermal conductivity ratio). Numerical results show a nanofluid buoyancy enhancement and a temperature distribution homogenization, when the Rayleigh number increases, all the more important and pushed to the right area of the enclosure, as the inclination angle of the enclosure is higher. For relatively low fin heights, the nanofluid buoyancy enhancement is all the more important and pushed to the right area of the enclosure as the inclination angle is high. As the fin height increases, the temperature distribution becomes more homogenous.

Highlights

Nanofluids [1,2,3] are used more and more in industrial heat transfer applications thanks to their thermo-physical properties, characterized by good capacity to store heat, without considerably increasing the temperature, and good thermal conductivity
As the Rayleigh number increased from Ra = 103 to Ra = 105, the nanofluid temperature distribution became globally more homogenous, especially in the central area of the enclosure, away from walls where the cold and hot temperatures were imposed
The flow and heat transfer of the Fe3O4 nanofluid were investigated within a specific rectangular enclosure

Summary

Introduction

Nanofluids [1,2,3] are used more and more in industrial heat transfer applications thanks to their thermo-physical properties, characterized by good capacity to store heat, without considerably increasing the temperature, and good thermal conductivity. The effects of enclosure inclination angle, porous Rayleigh number and nanoparticles volume fraction on nanofluid flow. Results show that the Nusselt number increases when nanoparticle volume fraction and porosity number increase, while the heat transfer rate decreases when the enclosure inclination angle increases at high porous Rayleigh numbers. The effects of emissivity and Rayleigh number on nanofluid flow and radiated/free convection heat transfer are investigated. Results show that the heat transfer is improved when nanoparticle volume fraction and Rayleigh number increase and when the cooled wall length is extended. This work aims to numerically investigate the flow and the heat transfer within a specific rectangular enclosure, filled with Fe3O4-Water nanofluid. The effects of Rayleigh number, enclosure inclination angle and fins height on nanofluid flow and heat transfer are studied.

Dimensionless Nanofluid Hydrodynamic Problem

Numerical Approach and Validation

Findings

Conclusions