Nano‐Encapsulated Phase Change Materials Heat Transfer Analysis Inside a Permeable Closed Chamber With Microorganisms

This work explores the coupled transport phenomena of heat and mass within a square cavity filled with a suspension of nano‐encapsulated phase change materials (NEPCMs) in water. The NEPCMs, consisting of n ‐eicosane as the latent heat core and polyvinyl alcohol as the protective shell, are utilized to enhance thermal energy storage and heat transfer. The system incorporates a heat source, porous medium, thermal radiation, magnetic parameter, and the influence of chemically reactive species with activation energy. Additionally, the motion of motile microorganisms is considered to study bio‐convective effects. A comprehensive mathematical model is developed using the Finite Element Method to solve the governing nonlinear equations. The analysis demonstrates that variations in porous structure, magnetic field strength, and radiation parameter significantly alter the flow structure, thermal behavior, and species distribution. The important findings reveal that, a rise in Cattaneo‐Christov heat flux parameter leads to reduced flow circulation and a broader temperature distribution, reflecting the impact of thermal relaxation on delaying heat propagation. As the values of heat source parameter rise, the formation of vortices becomes more pronounced and intricate, indicating enhanced thermal mixing and improved heat transfer within the cavity. The proposed model has several applications in thermal energy storage systems, solar thermal devices, and bio‐assisted thermal management applications.