Abstract
•Free convection due to hot lower wall and nonuniformly heated heater at a lesser temperature.•Enclosure with corrugated walls is more effective in entropy reduction as compared to flat walls.•The local entropy higher at the troughs lower at the crests.•Significant role of triangular cavity in minimizing entropy production.
All heat transfer phenomena are always escorted with entropy production and hence destruct the available work and energy resources. One way to minimize valuable energy rescores, especially in convective heat transfer augmentation situations, is to develop a thermal design that reduces the temperature differences inside the system and thus the entropy generation. This study analyzes an optimal thermal design for an augmented free convective situation considering a hybrid nanofluid flow in a corrugated triangular annulus heated by an underneath partial heater. Three approaches are applied to reduce entropy production: the corrugated walls, an inner heater at a lower non-uniform temperature, and the magnetic field effects. A numerical solution is presented for the normalized governing equations by a finite element method. A comparison with previously published investigation confirms the validity of results. The study reveals the influential role of the presented design in reducing entropy production due to the higher thermal conductivity of hybrid nanofluid. It is noticed that if the inner triangular body is heated at uniform or non-uniform temperature, keeping the magnitude of temperature lesser than the bottom heat source, the overall entropy significantly reduces. Moreover, overall, entropy is minimized if, instead of flat walls, corrugated walls are considered.