Enhancement of phase change material melting using nanoparticles and magnetic field in the thermal energy storage system with strip fins

Abstract

In this work, the numerical analysis of heat transfer and the enhancement of the melting of phase change material (PCM) in a three-dimensional cylindrical thermal energy storage system has been investigated. The RT82 is as PCM and the finite volume method is as the numerical solution method. Porosity-enthalpy method has been used to simulate the phase change melting process. The effects of strip fins, Fe3O4 nanoparticles, and uniform and non-uniform magnetic fields on the PCM melting are studied in details. Different modes have been considered for the non-uniform magnetic fields, both constant and variable with location. The predicted results display that the PCM melting time of the energy storage system using the new arrangement of strip fins is reduced by about 51 % compared to the that without fins. The addition of nanoparticles in PCM with volume fractions of 2.5 % and 5 % has improved the melting time by about 15 % and 22 % compared to those without nanoparticle. The use of a uniform magnetic field does not have much effect on the melting process without fins. But in the finned cases, in the initial melting (<1000 s), it has a noticeable effect on the amount of releasing energy in the desired system compared to the that without magnetic field, the mount of releasing energy is almost doubled. Using a variable magnetic field has a positive effect on the melting process of thermal energy storage and has improved the phase change process by about 39 % compared to the case without a field. It has also been concluded that in the case where the changes of the origin of the variable magnetic field (electric voltage) in the z-direction are parabolic, >60 % reduction in the melting time is noted.