Development, characterization, and charging performance of a novel nano-enhanced phase change material with lauric acid and fatty ester

This study enhances the thermal reliability of lauric acid, a promising phase change material with high latent heat, by mitigating degradation over thermal cycles. Lauric acid was blended with a fatty acid ester at varying weight fractions, and the optimal composition (70% lauric acid and 30% fatty acid ester) was determined based on latent heat retention between 200 and 1600 cycles. Differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and thermogravimetric analyses characterized the thermal, morphological, and chemical properties. The optimal blend maintained latent heat values of 140 J/g and 144 J/g after the 1st and 1600th cycles, confirming strong stability. To improve thermal conductivity, graphite and graphene nanoparticles were added. Their effects on melting behavior, latent heat, and supercooling were examined, and thermal diffusivity was measured via photothermal radiometry. A two-dimensional computational fluid dynamics model of a solar-assisted thermal energy storage system was developed to assess system performance by varying the aspect ratio of a shell-and-tube tank. Incorporating 4 wt% graphene into the optimal blend improved energy efficiency by 8.97% at an aspect ratio of 3.6, reaching 27.04%. The highest exergy efficiency, 2.72%, was achieved with the same composite at an aspect ratio of 2.4, marking 15.53% improvement. These results highlight the coupled influence of phase change material composition and system geometry on energy performance.