Free convection heat transfer and entropy generation in an odd-shaped cavity filled with a Cu-Al2O3 hybrid nanofluid

The present paper aims to analyze the thermal convective heat transport and generated irreversibility of water-Cu-Al2O3 hybrid nanosuspension in an odd-shaped cavity. The side walls are adiabatic, and the internal and external borders of the enclosure are isothermally kept at high and low temperatures of Thand Tc, respectively. The control equations based on conservation laws are formulated in dimensionless form and worked out employing the Galerkin finite element technique. The outcomes are demonstrated using streamlines, isothermal lines, heatlines, isolines of Bejan number, as well as the rate of generated entropy and the Nusselt number. Impacts of the Rayleigh number, the hybrid nanoparticles concentration (ϕhnf), the volume fraction of the Cu nanoparticles to ϕhnf ratio (ϕr), width ratio (WR) have been surveyed and discussed. The results show that, for all magnitudes of Rayleigh numbers, increasing nanoparticles concentration intensifies the rate of entropy generation. Moreover, for high Rayleigh numbers, increasing WR enhances the rate of heat transport

Study of paraffin-based composite-phase change materials for a shell and tube energy storage system: A mesh adaptation approach

Energy storage systems based on phase change materials are very innovative and useful in different engineering applications. The present study deals with numerical simulation of energy transport performance in a shell and tube energy storage system, including the paraffin wax or copper foam insertion with paraffin wax. The mathematical description of the considered problem consists of the basic equations grounded on the conservation laws with appropriate initial and boundary conditions. These equations were solved by the finite element method. The developed code was verified using the mesh sensitivity analysis and numerical data of other authors. Effects of the porosity, Rayleigh number, melting temperature, heat pipes location on melting flow structures and energy transport, and Nusselt number and melting volume fraction were scrutinized for charging and discharging modes. It was found that in the case of porous metal foam, the phase change intensity increases for the mentioned two regimes in comparison with pure paraffin wax. The vertical placement of the heating tubes results in the best charging time