Enhanced inorganic (SP26) phase change material with Na2HPO4 and graphene nanoplatelets for latent heat storage applications

Phase change material (PCM) thermal energy storage (TES) technology is a sustainable energy savings option that is especially lucrative in building energy management. PCM(s) can be applied directly for free cooling to reduce the building energy requirement for air conditioning. However, the practical application of PCMs remains hindered by challenges of poor heat transfer which causes long charging and discharging times, incongruent phase transitions, and poor thermal stability among others. To address these challenges, this study produces a nanocomposite-PCM containing 94.25 mass% PCM-sp26, 5 mass% disodium phosphate (DSP), and 0.75 mass% graphene nanoplatelets (GnP). The composite was observed to have faster melting and solidification cycles by 12.5 and 18.5%, respectively, compared to the base PCM-sp26. Thermal reliability is presented using temperature v time graphs, and material characterizations are presented using FTIR, XRD, and SEM analyses. The composite shows improved pH by ~ 21.3%, reduced sedimentation only noticeable after + 48 h compared to 30 min for the base PCM-sp26, a narrower phase change range of 27–27.5 °C, and ~ 8% larger density. The GnP improves the melting/solidification behavior of the base PCM without significantly altering the crystalline structure and functional groups of the material. Deterioration of the latent heat is limited to ~ 24.2% only, to provide a material with a storage capacity of ~ 136.4 kJ kg⁻¹.

Graphical abstract