Phase change materials: Agents towards energy performance improvement in inclined, vertical, and horizontal walls of residential buildings

Abstract

The numerical research of a wall (wall or ceiling) in the presence of phase change materials is undertaken in this work due to the relevance of energy consumption in buildings. One side of the wall has a high temperature, and the other side has a low temperature. The phase change materials is placed inside a cavity with an aluminum panel. For better examination, the number of cavities varies from 1 to 15 in the wall. The effect of different ceiling angles from 0 to 90° is evaluated. Graphene nanoparticles are added to increase the thermal conductivity of phase change materials, and the effects of varying the volume percentage of nanoparticles from 0 to 5% are explored. Finally, for phase change materials charging and discharging processes, as well as phase change time and wall temperature, a wall with variable numbers of cavities and angles for nano-phase change materials with varied volume percentage is simulated. The finite element method is used for the simulations by employing COMSOL. The findings of this research show that using nanoparticles in phase change materials decreases the melting time in the charging process and the freezing time in the discharging process, particularly with high volume percentages. Thus, in the cases of 1 and 15, a 5% enhancement in the number of nanoparticles in PCM intensifies the amount of molten PCM by 4.51% and 4.79%, respectively. The addition of nanoparticles also reduces the wall temperature. An increment in the number of cavities causes the charge and discharge processes to become faster. Further, it enhances the molten fraction of phase change materials in the charging process and the solid fraction of phase change materials in the discharging process.