Analysis of Entropy and Heat Transfer of Non-Newtonian Ferrofluid Under the Effect of Various External and Internal Factors

The target of this research is to investigate the amount of entropy production during natural convection inside a 2D chamber containing a non-Newtonian nanofluid using the lattice Boltzmann method. The chamber is exposed to uniform heat absorption/production and uniform and non-uniform magnetic field at different angles. The feature of the present work is to evaluate the effect of thermal radiation and the shape of the cavity cold wall in three shapes: smooth, curved and diagonal on the flow characteristics. Application in the design of electronic coolers and solar collectors is one of the practical cases of this numerical research. Acceptable agreement of the obtained results with previous related studies confirmed the validity of the presented results. Based on the results, the presence of radiation parameter leads to the improvement of heat transfer, which is more evident due to the increase of fluid power-law index. In addition to reducing the Nusselt value for enhancing the fluid power-law index, the effectiveness of the presence of the magnetic field in reducing the entropy and heat transfer rate enhances as the fluid power-law index decreases. It is feasible to attain the flow strength and the Nusselt value up to 40% and 61% more, respectively, by applying a vertical and non-uniform magnetic field. Although for heat production mode, there will be the lowest value of thermal performance index and the Nusselt value, the greatest influence of the magnetic field is observed in the heat production mode. By designing the wall in a smooth shape, in addition to increase the thermal performance coefficient, it is possible to decline the Bejan value.