Development of a shape-stabilized phase change material utilizing natural and industrial byproducts for thermal energy storage in buildings

A comprehensive study was conducted to develop and utilize a novel shape-stabilized phase change material utilizing two abundantly available and low-cost natural materials, namely scoria and expanded perlite and an industrial byproduct, heavy oil ash, in combination with polyethylene glycol. The thermal and energy storage characteristics of the composite materials were evaluated with the aim of using them to conserve energy in the domestic facilities. The results of differential scanning calorimetry showed that expanded perlite composite has the highest melting and solidification latent heat values, 150.7 J/g and 134.6 J/g, respectively, compared to scoria and oil ash composite. However, expanded perlite composite has lower thermal conductivity compared to other composites. Consequently, a novel system incorporating carbon nano tubes (0.5 wt.% and 1 wt.%) in the expanded perlite composite was developed to improve its thermal conductivity. The thermal conductivity (0.453 W/m.K) of the new system with 0.5% carbon nano tubes is remarkably more than that of commonly used phase change materials. Further, the developed PCM with 0.5% carbon nano tubes can transform sunlight into thermal energy with a solar-to-thermal energy conversion efficiency of 59.4% and it has a thermal conductivity that is 97% more than that of polyethylene glycol alone. Besides, the newly developed PCM also shows excellent energy storage and release performance. All these favorable characteristics indicate that the developed phase change material can be beneficially utilized in thermal storage systems.