Investigation of temperature-dependent structural and thermal behavior in capric acid–silica nanocomposites via molecular dynamics simulation

Energy storage systems have become increasingly vital to the transition to renewable energy, enabling the effective storage of excess energy and its release during periods of peak demand. In this study, molecular dynamics simulations were employed to investigate the structural and thermal properties of a nanocomposite comprising capric acid and silica aerogel nanoparticles. The objective was to assess its potential for thermal energy storage applications. The simulation process was divided into two phases, each lasting 10 ns, resulting in a total simulation time of 20 ns. During the equilibration phase, the system stabilized, with the temperature and kinetic energy converging to 300 K and 0.98 kcal/mol, respectively, indicating the system reached thermal and dynamic equilibrium. In the final phase, the thermophysical properties of the system were analyzed as a function of initial temperature, ranging from 300 K to 350 K. The results indicated that as the temperature increased, the maximum density decreased from 0.032 atom/ų to 0.0273 atom/ų, while the maximum velocity and temperature increased from 0.0015 Å/fs to 0.0029 Å/fs and from 364.64 K to 396.17 K, respectively. On the other hand, the heat flux decreased slightly from 8.95 W/m² to 8.57 W/m², and the thermal conductivity decreased from 0.34 to 0.25 W/m·K. Additionally, the charging time decreased from 4.18 ns to 3.70 ns, whereas the discharging time changed only marginally, decreasing from 5.72 ns to 5.71 ns. These findings provided a fundamental understanding of the material's nanoscale thermal behavior, which may inform future studies evaluating its suitability for thermal energy storage applications.