Building roof with conical holes containing PCM to reduce the cooling load: Numerical study

The thermal effectiveness of a building's roof with phase change material (PCM) is presented in this paper. The considered model consists of a concrete slab with vertical cone frustum holes filled with PCM. The objective of incorporating the PCM into the roof structure is to utilize its high latent heat of fusion to reduce the heat gain during the energy demanded peak hours, by absorbing the incoming energy through the melting process in the roof before it reaches the indoor space. The thermal effectiveness of the proposed roof-PCM system is determined by comparing the heat flux at the indoor surface to a roof without the PCM during typical working hours. A parametric study is conducted to assess the effects of the cone frustum geometry, and the kind of PCM used. The n-Eicosane shows the best performance among the examined PCMs, and the conical geometry of the PCM container is the best in term of thermal effectiveness. The results indicate that the heat flux at the indoor surface of the roof can be reduced up to 39% for a certain type of PCM and geometry of PCM cone frustum holes. (C) 2011 Elsevier Ltd. All rights reserved.