2LEMI (Laboratory of Energy, Mechanics and Engineering), Department of Mechanical Engineering, Faculty of Technology, University M’Hamed Bougara Boumerdes, 35000, Algeria
3Laboratory of Hydrocarbons Physical Engineering, Faculty of Hydrocarbons and Chemistry, University of M’Hamed Bougara Boumerdes, 35000, Algeria
4Department of Mechanical Engineering, Mechanical Engineering Faculty, Yildiz Technical University, Istanbul, 34349, Türkiye
Abstract
In this study, we numerically investigate the thermal behavior of two types of nanofluids under mixed convection, both subjected to the same operating conditions. One nanofluid contains nanoencapsulated phase change material particles with gallium cores and silica shells (Ga@
SiO2), while the other uses conventional SiO2 nanoparticles. This approach enables us to assess the impact of the latent heat associated with the PCM core and provides a clearer understanding of its influence on heat transfer performance. The physical model is a square cavity with a
top moving wall and a rotating inner cylinder. The analysis is performed for Richardson numbers between 0.1 and 100, while the nanoparticle concentration varies from 0% to 4%. A finite volume technique is employed to solve the governing equations for momentum and energy. Validation
against published results confirms the accuracy of our numerical approach. It has been found that the Ga@SiO2/water nanofluids perform better than the SiO2/water nanofluids. At Ri = 10 and a particle fraction of 4%, the Ga@SiO2/water nanofluid achieves a maximum heat transfer
enhancement of 20.31%, whereas the SiO₂/water nanofluid only reaches 1.68%. The observed enhancement can be explained by the combined contribution of the phase change occurring within the gallium core, which allows energy to be absorbed and released. The addition of Ga@SiO₂
particles enhances heat transfer, making this suspension suitable for thermal applications.
