Conjugate heat transfer in a porous cavity filled with nanofluids and heated by a triangular thick wall

• Published in: International journal of thermal sciences 2013-05, Vol.67, p.135-151
• Main Authors: Chamkha, Ali J., Ismael, Muneer A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cavity; Chemistry; Colloidal state and disperse state; Condensed matter: structure, mechanical and thermal properties; Conjugate heat transfer; Darcy model; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Flows through porous media; Fluid dynamics; Fundamental areas of phenomenology (including applications); General and physical chemistry; Heat transfer; Nanofluids; Nonhomogeneous flows; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physics; Porous medium; Theoretical studies. Data and constants. Metering; Thermal properties of condensed matter; Thermal properties of small particles, nanocrystals, nanotubes; Triangular solid wall
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/j.ijthermalsci.2012.12.002

The conjugate natural convection–conduction heat transfer in a square domain composed of nanofluids filled porous cavity heated by a triangular solid wall is studied under steady-state conditions. The vertical and horizontal walls of the triangular solid wall are kept isothermal and at the same hot temperature Th. The other boundaries surrounding the porous cavity are kept adiabatic except the right vertical wall where it is kept isothermally at the lower temperature Tc. Equations governing the heat transfer in the triangular wall and heat and nanofluid flow, based on the Darcy model, in the nanofluid-saturated porous medium together with the derived relation of the interface temperature are solved numerically using the over-successive relaxation finite-difference method. A temperature independent nanofluids properties model is adopted. Three nanoparticle types dispersed in one base fluid (water) are investigated. The investigated parameters are the nanoparticles volume fraction φ (0–0.2), Rayleigh number Ra (10–1000), solid wall to base-fluid saturated porous medium thermal conductivity ratio Kro (0.44, 1, 23.8), and the triangular wall thickness D (0.1–1). The results are presented in the conventional form; contours of streamlines and isotherms and the local and average Nusselt numbers. At a very low Rayleigh number Ra = 10, a significant enhancement in heat transfer within the porous cavity with φ is observed. Otherwise, the heat transfer may be enhanced or deteriorated with φ depending on the wall thickness D and the Rayleigh number Ra. At high Rayleigh numbers and low conductivity ratios, critical values of D, regardless of φ, are observed and accounted. ► Conjugate heat transfer in a square porous cavity heated diagonally and filled with nanofluids is studied. ► Heat transfer may be enhanced or deteriorated with increasing nanoparticles volume fraction. ► The Rayleigh number and the triangular wall thickness are important factors. ► Copper nanoparticles give greater heat transfer than alumina oxide and titanium oxide.