Study of thermal and hydrodynamic characteristics of water-nano-encapsulated phase change particles suspension in an annulus of a porous eccentric horizontal cylinder

•The free convection of nano-encapsulated phase change material (NEPCM)-suspension in a porous enclosure is addressed.•The NEPCM particles are made of a phase change core which is encapsulated in a polymer shell.•The NEPCM particles are suspended in a host liquid and can circulate with the host fluid and store/release latent heat.•The NEPCM control parameters such as the fusion temperature, Stefan number, and volume fraction are investigated.•The phase change core of particles improves the heat transfer rate, and the improvement depends on the fusion temperature. In this paper, the thermal and hydrodynamic characteristics of a suspension with water-Nano-Encapsulated Phase Change Material (NEPCM) in an annulus of a porous eccentric horizontal cylinder are investigated. The NEPCM particles have a core-shell structure and stability suspended in water. Hence, the particles, along with the liquid, could freely circulate inside the annuli of the horizontal cylinder due to the buoyancy forces. The cores of these particles are made from a Phase Change Material (PCM). Moreover, such cores are in a continuous exchange of heat transfer between the solid and liquid phases. The heat transfer is acting in a combination of absorption, storage, and release mechanisms. The governing equations for the fluid motions and conservation of energy could be written in partial differential forms and by using the appropriate non-dimensional variables converted into non-dimensional ones. Then, the numerical approach is applied by implementing the finite element method (FEM) to solve such equations iteratively. The impact of various non-dimensional parameters including the fusion temperature, Stefan number, Rayleigh number, Darcy number, the volume fraction of nanoparticles, and eccentricity of the inner cylinder is addressed on the flow and heat transfer. It is observed that the most favourable fusion temperature ranges for the maximum heat transfer rate vary as a function of the Rayleigh number. In addition, the heat transfer rate can be enhanced by applying the phase change core of nanoparticles.