Role of graphitized mesoporous carbon on solidification and melting characteristics of water for cool thermal storage

Abstract

Cool thermal energy storage systems (CTES) using phase change materials (PCM) are paramount in the energy management of buildings. This work aims to investigate the role of graphitized mesoporous carbon (GMC) on the thermal storage behavior of water based nanofluid PCM (NFPCM) in a spherical capsule. The NFPCMs exhibit a lower contact angle, indicating a reduction in the nucleation energy barrier. Thermal conductivity of NFPCM shows an enhancement of 36% with the presence of graphitized walls and isotropic nature of GMC. Temperature–time history method is used to evaluate the latent heat of fusion for the NFPCMs and the results are compared with differential scanning calorimetry measurements. Addition of GMC shortens the solidification duration by 6% and reduces the subcooling of NFPCM compared to base PCM. The charging results of NFPCMs demonstrate a cool energy storage of 96% in accelerated mode. The melting rate of NFPCM is expedited at a minimal GMC concentration and melting duration prolongs with further GMC addition. In conclusion, the proposed NFPCMs exhibiting a lower subcooling, improved nucleation behavior and accelerated mode of charging shows great potential for CTES applications.