Analysis of inherent irreversibility in a reacting variable viscosity MHD mixed convection of nanofluid in a space between two concentric pipes

Abstract

This study explores mixed convection of an electrically conducting and reacting variable viscosity nanofluid in a space between two concentric vertical pipes under the combined influence of an imposed magnetic field, variable viscosity, buoyancy forces, viscous dissipation, Joule heating, axial pressure gradient, velocity slip, thermophoresis and Brownian motion. Based on the Buongiorno two-phase nanofluid model assumption, the nonlinear differential equations governing the problem are obtained and numerically solved via the shooting technique with the Runge-Kutta- Fehlberg integration scheme. The nanofluid velocity, temperature and concentration profiles are further utilized to compute the skin friction, Nusselt number, Sherwood number, entropy generation rate and the Bejan number. The impact of various emerging parameters is examined and presented graphically. It was found that  the entropy generation rate escalates with an upsurge in buoyancy forces, reaction rate, thermal Biot number, thermophoresis and Brownian motion. In contrast, a rise in magnetic field intensity lessens it.