Dynamic thermal behavior of a nanocomposite phase change material roof with an elevated overhead roof subjected to sinusoidal variations in external temperature

A two-dimensional heat transfer model for a nanocomposite phase change material (PCM) roof with an open roof was developed utilizing the enthalpy-porosity approach. This study numerically examined and discussed the effects of sinusoidal fluctuations in external temperature on the variations of internal and external surface temperatures, heat fluxes, and temperature distribution of four distinct roofs. These roofs included an ordinary roof without PCM, as well as three different nanocomposite PCM roofs with varying positions of the nanocomposite PCM layer. The computed results indicate that the presence of a nanocomposite PCM layer on the roof of the building has the potential to decrease the magnitude of the internal surface temperature fluctuations of the roof and improve the time delay between external and internal temperature changes. The placement of the nanocomposite PCM layer has varying impacts on the heat flux of the internal surface of the roof. Integrating the nanocomposite PCM layer inside the middle of the roof yields superior results compared to positioning it on either the exterior or interior surface of the roof. The temperature distribution within the roof is notably influenced by variations in external temperature. Specifically, the presence of a nanocomposite PCM layer on the interior surface of the roof enhances the amount of heat into the roof.