Analysis and optimization of phase transition in L, U and T-shaped cavities having encapsulated phase change material during nano-enhanced non-uniform magneto convection

Abstract

Container shape and operating parameters are among the important factors that determine the efficiency of phase change material integrated energy systems along with the material. In this study, phase transition performance of encapsulated phase change material in L, U and T shaped enclosures are numerically investigated under spatially varying magnetic field. The numerical analysis is conducted for a range of Hartmann number (Ha) values (from 0 to 80), magnetic field inclination ( γ ) (from 0 to 90), and non-uniform amplitude (Amp) (from 0 to 0.9). To obtain the maximum liquid fraction amount for a specified time period, an optimization study is conducted to determine the optimal magnetic field parameters for each of the cavities. It is observed that magnetic field controls the vortex number and its distribution for each of the cavities. Among different cavities, the lowest impact on transition time (t-C) is found for T-shaped cavity. By varying strength of magnetic field, t-C varies by roughly 21.4 % and 23.4 % for L and U-shaped cavities while they become 13 % and 11 % with varying inclination of magnetic field. The amplitude of non-linear part of magnetic field contributes to phase change dynamics. The highest amount of liquid fraction for L, U and T-shaped cavities is achieved at optimal values of (Ha, γ , Amp) = (33.33, 46.5, 0.825), (56.07, 6.35, 0.783), and (79.11, 80.03, 0.836), respectively by using optimization. When compared to the reference scenario of using pure fluid without magnetic field, the optimization provides the largest improvement in the liquid fraction amount for T-shaped cavities, followed by U and L-shaped cavities. The increment amounts for these enclosures are found as 18.3 %, 12.3 %, and 10.4 %. Using nanofluid is found to be beneficial for accelerating the process for all cavities. The outcomes show that enclosure type is very important for phase change process dynamics when varying operating parameters.