Second law analysis of MHD mixed convection heat transfer in a vented irregular cavity filled with Ag–MgO/water hybrid nanofluid

• Published in: Journal of thermal analysis and calorimetry 2019-08, Vol.137 (3), p.1113-1132
• Main Authors: Benzema, Mahdi, Benkahla, Youb Khaled, Labsi, Nabila, Ouyahia, Seif-Eddine, El Ganaoui, Mohammed
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Computational fluid dynamics; Empirical equations; Engineering Sciences; Entropy; Fluid flow; Hartmann number; Heat transfer; Inorganic Chemistry; Laws, regulations and rules; Magnesium oxide; Magnetic fields; Measurement Science and Instrumentation; Nanofluids; Nanoparticles; Partial differential equations; Physical Chemistry; Polymer Sciences; Reynolds number; Thermal boundary layer; Thermal conductivity
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-019-08017-x

The present paper investigates numerically the effect of an external magnetic field on heat transfer and entropy generation of Ag–MgO (50:50 vol%)/water hybrid nanofluid flow in a partially heated irregular ventilated cavity. A finite-volume FORTRAN code has been written to solve the governing partial differential equations. New empirical correlations specifically dedicated to predict the dynamic viscosity and the thermal conductivity of the considered hybrid nanofluid were employed. After validation of model, the analysis has been done for a wide range of Reynolds number (10 ≼  Re  ≼ 600), Hartmann number (0 ≼  Ha  ≼ 80) and total nanoparticle volume fraction (0 ≼  φ  ≼ 0.02). The results are presented in terms of streamlines, isotherms and isentropic lines as well as the average Nusselt number ( Nu m ), the average entropy generation ( S gen , m ) and the Bejan number ( Be avg ). The criterion ξ  =  S gen , m / Nu m is adopted to discuss the thermal performances of the system. The results reveal that the intensification of the magnetic field tends to attenuate the heat transfer convection and to reduce the thickness of the thermal boundary layer, close to the active walls. Globally, adding nanoparticles to the base fluid improves the heat transfer but increases the total entropy generation.