Optimum constituents for MHD heat transfer of nanofluids within porous cavities

Abstract

In this paper, the Taguchi experimental design method is utilized to determine optimum combination of constituents for MHD heat transfer of nanofluids in porous cavities in natural and mixed convection configurations. The tested constituents include ethylene glycol and water for the base fluid, silver, aluminum oxide, carbon nanotubes, cobalt, copper, copper oxide, ferroferric oxide, and titanium oxide for the nanoparticles, and aluminum foam and glass balls for the solid matrix. The governing equations are those presented by Buongiorno that include Brownian diffusion and thermophoresis effect which are solved numerically. In the Taguchi experimental design method, the mean Nusselt number is considered as the performance parameter and an L16 orthogonal array is used as the experimental plan for the control factors. Analysis is undertaken for several Hartmann numbers (i.e., $$Ha = 0, \,1,\, 30$$ ). The optimum design in all of the circumstances is achieved for CuO–water nanofluid within glass balls. In the mixed convection configuration, the most important factor affecting the heat transfer is found to be the solid matrix material. But, in the natural convection configuration, with an increase in the strength of the magnetic field, the highest contribution shifts from the nanoparticles type to the solid matrix material. The outcomes of this contribution provide insight into design of thermal systems.