Lattice-Boltzmann numerical simulation of double-diffusive natural convection and entropy generation in an n-shaped partially heated storage tank

Energy and mass storage in various single-phase fluid flows is of particular interest, as the world currently faces energy challenges. Double-diffusive natural convection in an n-shaped storage tank is numerically studied which can be a general guideline to maintain a storage tank with higher exergy. Lattice-Boltzmann's approach in an in-house computational code is used to simulate the problem. To display the results, it is considered that the Rayleigh number lies between 103 and 105, and the Lewis number in the range of 0.1 and 10. The average Nusselt and Sherwood number, as well as entropy generation, showing the energy loss, are illustrated. It is observed that the average Nusselt and Sherwood number rises with increasing Rayleigh number and buoyancy ratio. Further, the average Sherwood number boosts by increasing the Lewis number. The most promising parameter in increasing the heat and mass transfer are found to be Rayleigh and Lewis number, respectively, with a maximum 300 percent improvement. The flow friction can be regarded as the main source of entropy generation, with a share of 90 percent. The Rayleigh number increment from 103 to 105 leads to the rise in the total entropy generation by approximately fivefold.