Computational modelling and Simulation of Entropy Generation and heat Transfer analysis in Triangular Solar Stills Using TiO₂ Nanofluid flow with the Darcy-Brinkman Forchheimer and Ree-Eyring Model

Resumen

This research focused on entropy generation in the triangular solar still based on a nanofluid of TiO₂ under the influences of magnetohydrodynamics (MHD), double-diffusive convection, and the Darcy-Brinkman-Forchheimer and Ree-Eyring models. The non-dimensional forms of the governing equations were solved by means of the Galerkin Finite Element Method (FEM) using COMSOL Multiphysics. The analysis of the major parameters with regard to flow, temperature distribution, entropy generation, and their combined effect on heat transfer has been supported with comparative sketches and tables, all validated by grid independence tests to assure computational accuracy. It is found that the flow circulation and hence convective heat transfer increased with increasing values of the Ree-Eyring parameter (η). It was also found that for high values of the Ree-Eyring parameters, the nature of heat transfer progressively changed and became conduction dominant beyond a certain value. Increased Darcy numbers (Da) promote a flow towards convection-dominance in heat transfer processes by allowing a more superior permeability of flow and local Nusselt number. Increased porosity (ϵ) reduces resistance and on the other hand strengthens convection and temperature uniformity with a graph where the local Nusselt number is taken down to a lower level because of reduced effective thermal conductivity. Magnetic effects (Ha) suppress convection but bring about a considerable increase of 100% in the magnetic entropy generation while reducing the viscous entropy generation by

25.77%. These will provide very good guidance in model optimization of nanofluid based solar stills, following the interrelationship of MHD, fluid dynamics, and thermal efficiencies of sustainable energy systems.