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Numerical study on the effect of non-uniform magnetic fields on melting and solidification characteristics of NEPCMs in an annulus enclosure

Rostami Dibavar, M., Mohammadpourfard, M., Mohseni, F., Zeinali Heris, S.
Energy conversion and management 2018 v.171 pp. 879-889
electric current, enthalpy, liquid-solid interface, liquids, magnetic fields, mathematical models, melting, nanofluids, solidification
In this study, the effects of non-uniform magnetic fields on melting and solidification of Nanoparticle-Enhanced Phase Change Materials (NEPCM) in an annulus enclosure are numerically investigated. Magnetic fields are applied on electrically conductive magnetic nanofluids by positioning a wire carrying the electric current in the center of the annulus. For the numerical simulation, a homogenous single-phase model and finite volume method are used and the melting and solidification processes are studied using the enthalpy-porosity method, where, instead of explicitly tracking the liquid-solid interface, the so-called liquid fraction quantity is computed based on the enthalpy balance in each cell and in each time iteration. The results show that, for the case with non-electrical conductive magnetic nanofluids, by increasing the magnetic number, the time required for the melting and solidification processes are reduced up to 39.91% and 14.29%, respectively. However, for the case with electrical conductive magnetic nanofluids at Ra = 104 and at specific magnetic numbers, the rate of both melting and solidification processes decreases by increasing the Hartmann number.