Optimizing heat flow: Nano-encapsulated phase change materials in vibration-enhanced gravity-driven thermal convection

In cavities differentially heated at the sides and subjected to mechanical vibration, the natural convection incoming from buoyancy effects is not the only factor affecting the flow dynamic and heat transfer. The current work aims to address vibrational convection in a square chamber filled with a Nano-Encapsulated Phase Change Material (NEPCM) suspension. The non-dimensional equations of fluid and heat flows in the cavity are developed and solved numerically. The gravity term in the momentum equation is modified to include the effect of vibration. It is shown that the vibrational Rayleigh number has the most effect on the convective heat transfer, followed by the conductivity of the NEPCM suspension. Increasing the vibrational Rayleigh number from 10³ to 10⁷ leads to up to 3 times rise in the time-averaged Nusselt number. The NEPCM concentration has a moderate influence, as around 12% increase in the time-averaged Nusselt number is found when a 5% volume fraction of particles is employed. An increase in the Stefan number from 0.2 to 0.8 is associated with a 6.1% reduction in the time-averaged Nusselt number. Additionally, the peak heat transfer is achieved at the melting point of 0.5, with a 6.5% increase compared to the melting temperature of 0.1.