▎ 摘　　要

This research paper describes the experimental investigation of the phase change characteristics of deionized (DI) water with the addition of functionalized graphene nanoplatelets (FGNP) in a spherical container used in cool thermal energy storage (CTES) systems. The nano-enhanced phase change materials (NEPCMs) are developed by the dissolution of FGNP in the mass concentrations of 0.25%, 0.50%, and 0.75% with DI water. The thermal conductivity (TC) and phase change enthalpy (H) of the NEPCMs were measured experimentally using the transient hot-wire method and DSC 214 polymer, respectively. At heat transfer fluid (HTF) temperatures of -10 degrees C and 15 degrees C, the mass fraction of 0.75 improves thermal conductivity by 48.2% and 33.2% in the solid and liquid phases, respectively. At a heating rate of 1K min-1, the addition of FGNP significantly reduces the H of the base PCM in both crystallization and melting processes. The maximum reduction in crystallization and melting time was recorded to be 32.4% and 52.4% in a spherical container with the addition of maximum concentration of FGNP at the HTF temperatures of -8 degrees C and 25 degrees C, respectively.