Investigation of Heat Transfer of Nanoencapsulated Phase Change Material and Water in a Trapezoidal Cavity With a Sliding Wall

In recent years, nanoencapsulated phase change materials (NEPCMs) have gained great interest in thermal management and control applications. This paper addresses the mixed convection of water and NEPCM confined within a lid-driven trapezoidal cavity. The bottom wall of the cavity is of a wavy shape; moreover, the cavity includes a hot flame and is subjected to a magnetic field. The Galerkin-finite element method was used to address the system governing equations and the results obtained were validated by preceding research works. The impacts of bottom wall undulation number (N = 1–4), Hartmann number (Ha) of 0–100, Reynolds number (Re) of 0–500, and hot flame location (left, center, and right) on thermal fields and flow pattern are presented and discussed. The findings show that placing the hot flame at the center gives the maximum thermal transfer rate while augmenting the undulation number of the bottom wall obstructs the liquid flow and hence reduces heat transmission rates. At the maximum Reynolds number, increasing the undulation number of the bottom wall from 1 to 4 and Ha from 0 to 100 reduces the Nusselt number by 26.7% and 54%, respectively.