A numerical investigation of heat transfer and entropy generation during jet impingement cooling of protruding heat sources without and with porous medium. (1st January 2015)

• Record Type: Journal Article
• Authors: Lam, Prasanth Anand Kumar; Arul Prakash, K.
• Is Part Of: Energy conversion and management. Volume 89(2015)
• Page Start: 626
• Page End: 643
• Publication Date: 2015-01-01
• Subjects: Impinging jet -- Porous medium -- Darcy–Forchheimer–Brinkman model -- SUPG-finite element method -- Entropy generation -- Nusselt number; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2014.10.026
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: Effect of porous layer on impingement cooling of protruding heat sources is studied. Entropy generation due to heat transfer and fluid friction has been predicted. Local and surface averaged Nusselt number along heat sources are analyzed in detail. Optimum model for maximum heat transfer and minimum entropy generation is reported. Abstract: In the present study, fluid flow and thermal characteristics associated with forced convection cooling of an array of discrete protruding heat sources mounted on impingement plate of channel by an impinging laminar jet is investigated for various Reynolds number ( Re ) and channel height ( H / L ) . It is observed that, the magnitude of average Nusselt number for all heat sources increases with increasing Re and decreasing H / L, except the regions of heat sources covered by recirculation bubbles which may be due to accumulation of heat resulting in hot spots. In order to eliminate these hot spots, a porous layer is attached to the impingement plate. A parametric study is conducted to predict the performance of porous layer on fluid flow pattern, heat transfer and entropy generation for various values of Darcy number ( Da ), Reynolds number ( Re ), channel height ( H / L ), porosity ( ∊ ) and porous layer thickness ( h / H ) . For the purpose, equations governing two-dimensional, time-dependent, incompressible and laminar flow are solved in a Cartesian framework by using Streamline Upwind Petrov–Galerkin (SUPG) Finite Element (FE) method. The generalized Darcy–Forchheimer–Brinkman model is adopted to model the flow in porous medium. The recirculation bubbles on heat sources are completely eliminated with the inclusion of porous layer at Darcy number, Da = 10 - 2 . The magnitude of overall Nusselt number and global entropy generation due to heat transfer ( S θ, Ω ‾ ) and fluid friction ( S ψ, Ω ‾ ) increases with increasing Da, Re, h / H and decreasing ∊ and H / L . The optimum configuration for maximum heat transfer and minimum entropy generation is observed at Da = 10 - 2, Re = 1000, H / L = 1.0, h / H = 0.75 and ∊ = 0.5 .