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Simulating natural convection and entropy generation of a nanofluid in an inclined enclosure under an angled magnetic field with a circular fin and radiation effect

Journal: Journal of Thermal Analysis and Calorimetry
Author:  Masoud Afrand
Link: https://link.springer.com/article/10.1007/s10973-019-08729-0
Abstract:

Natural convection and radiation heat transfer of alumina (Al2O3)–water nanofluid are assessed in an enclosure under a magnetic field in different angles. The enclosure is a cavity at an angle of 45° with respect to the horizon, and a circular quadrant fin with the temperature Th is placed at the bottom corner of the cavity. The right wall is considered at the temperature Tc, and the rest of the walls are defined as adiabatic. The governing equations of flow are solved using algebraic finite volume method and the SIMPLE algorithm. In this work, the entropy generation is also evaluated other than heat transfer. The parameters in the present work include Rayleigh and Hartmann numbers, radiation parameter, magnetic field angle, nanoparticles volume fraction and aspect ratio. The results indicate higher Nusselt number and entropy generation and a lower Bejan number for a higher Rayleigh number and a lower Hartmann number. Addition of 6% of the nanoparticles causes an increase of 10% in the heat transfer rate and 11% in the entropy generation in the absence of radiation. The addition of the radiation mechanism to the enclosure leads to an increase in the heat transfer rate and entropy generation. It is also demonstrated that the vertical magnetic field is more intense than the horizontal magnetic field in the enclosure. With an increase in the fin aspect ratio from 0.3 to 0.7, the rate of heat transfer and entropy generation increases by 36 and 27%, respectively.