MHD Mixed Double‐Diffusive Convection of NEPCM in Porous Staggered Lid‐Driven Cavities

This article employs numerical methods to study double‐diffusion convection when nano‐encapsulated phase‐change materials (NEPCMs) suspension flows through a porous staggered lid‐driven cavity that is subjected to a magnetic field. The upper wall motion, which moves in one direction, while the lower wall motion, which moves in the opposite direction, creates shear‐driven flow at the same time that vertical boundaries receive thermal and solutal gradients. The research employs a finite‐element method to solve governing equations with NEPCM latent heat effects for examining how Reynolds number ( Re = 1–100), Darcy number ( Da = 10 −5 –10 −2 ), Hartmann number ( Ha = 0–100), and Lewis number ( Le = 0.1–10) affect flow behavior and phase‐change distribution and heat transfer and mass transfer. The research results established that permeability is the primary factor determining transport behavior. The Nusselt number increases from 0.16 to 4.26 while the Sherwood number rises from 1.51 to 10.82 at Re = 1 when we increase the Da from 10 −5 to 10 −2 , which shows the change from diffusion‐dominant transport to convection‐dominant transport. Low permeability ( Da = 10 −4 ) enables heat transfer to increase by approximately 140% when Re increases from 1 to 100, whereas high permeability ( Da = 10 −2 ) provides only a 15% improvement. Mass transfer decreases by over 90% while heat transfer diminishes by up to 35% when we increase the Lewis number from 0.1 to 10 because solutal buoyancy becomes weaker. A strong magnetic field ( Ha = 100) leads to reductions in the Nusselt and Sherwood numbers of approximately 46% and 69%, respectively. The numerical data establish the specific parameters required to develop optimal NEPCM‐based porous thermal energy storage systems and magnetically controlled cooling systems. This work aligns with and supports Sustainable Development Goal 7 (SDG7) and Sustainable Development Goal 11 (SDG11) by driving efficient NEPCM‐based thermal systems that facilitate low‐emissions energy utilization.