Impact of finite wavy wall thickness on entropy generation and natural convection of nanofluid in cavity partially fille
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ORIGINAL ARTICLE
Impact of finite wavy wall thickness on entropy generation and natural convection of nanofluid in cavity partially filled with non-Darcy porous layer Ammar I. Alsabery1,2
•
Muneer A. Ismael3 • Ali J. Chamkha4 • Ishak Hashim2
Received: 18 July 2019 / Accepted: 5 February 2020 Ó Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract This paper investigates the natural convection inside a partially layered porous cavity with a heated wavy solid wall; the geometry is encountered in compact heat exchangers. Alumina nanoparticles are included in the water to enhance the heat exchange process. The incidental entropy generation is also studied to evaluate the thermodynamic irreversibility. The nanofluid flow is taken as laminar and incompressible while the advection inertia effect in the porous layer is taken into account by adopting the Darcy–Forchheimer model. The problem is explained in the dimensionless form of the governing equations and solved by the finite element method. The Darcy number (Da), porosity of the porous layer (e), number of undulations (N), and the nanoparticles volume fraction (/) are varied to assess the heat transfer and the incidental entropy generation. It is found that the waviness of the solid wall augments the average Nusselt number and minimizes the generation of entropy. The results show for some circumstances that the Nusselt number is augmented by 43.8% when N is raised from 0 (flat solid wall) to 4. It is also found that the porosity of the porous layer is a more crucial parameter than its permeability, where a 37.4% enhancement in the Nusselt number is achieved when the porosity is raised from 0.2 to 0.8. Keywords Entropy generation Natural convection Nanofluid-porous composite Forchheimer model Wavy solid wall FEA
1 Introduction A nanofluid encompassed by an undulated-wall enclosure is an appropriate and convenient strategy to follow for enhancing the natural heat convection. If the natural & Ammar I. Alsabery [email protected] 1
Refrigeration and Air-Conditioning Technical Engineering Department, College of Technical Engineering, The Islamic University, Najaf, Iraq
2
Department of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
3
Mechanical Engineering Department, Engineering College, University of Basrah, Basrah 61004, Iraq
4
Department of Mechanical Engineering, Prince Sultan Endowment for Energy and the Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952, Saudi Arabia
convection coincides with a transport process in porous media, this will be of great interest in many technical and engineering applications. Treatment of toxicity exhausted from automobiles, heat exchangers, cooling of gas turbine blades [1], filtration processes, crystal solidification, etc. are sample examples of these applications. The topic of nanofluid has become familiar since the research of Choi and Eastman [2] who did no
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