Abstract
The combined effects of surface rotation and using binary nanoparticles on the phase change process in a 3D complex-shaped vented cavity with ventilation ports were studied during nanofluid convection. The geometry was a double T-shaped rotating vented cavity, while hybrid nanofluid contained binary Ag-MgO nano-sized particles. One of the novelties of the study was that a vented cavity was first used with the phase change-packed bed (PC-PB) system during nanofluid convection. The PC-PB system contained a spherical-shaped, encapsulated PCM paraffin wax. The Galerkin weighted residual finite element method was used as the solution method. The computations were carried out for varying values of the Reynolds numbers (100 & LE;Re & LE;500), rotational Reynolds numbers (100 & LE;Rew & LE;500), size of the ports (0.1L1 & LE;di & LE;0.5L1), length of the PC-PB system (0.4L1 & LE;L0 & LE;L1), and location of the PC-PB (0 & LE;yp & LE;0.25H). In the heat transfer fluid, the nanoparticle solid volume fraction amount was taken between 0 and 0.02%. When the fluid stream (Re) and surface rotational speed increased, the phase change process became fast. Effects of surface rotation became effective for lower values of Re while at Re = 100 and Re = 500; full phase transition time (tp) was reduced by about 39.8% and 24.5%. The port size and nanoparticle addition in the base fluid had positive impacts on the phase transition, while 34.8% reduction in tp was obtained at the largest port size, though this amount was only 9.5%, with the highest nanoparticle volume fraction. The length and vertical location of the PC-PB system have impacts on the phase transition dynamics. The reduction and increment amount in the value of tp with varying location and length of the PC-PB zone became 20% and 58%. As convection in cavities with ventilation ports are relevant in many thermal energy systems, the outcomes of this study will be helpful for the initial design and optimization of many PCM-embedded systems encountered in solar power, thermal management, refrigeration, and many other systems.