Molecular dynamics study of the effects of the porosity and initial pressure on phase transition of porous phase change materials

Using renewable energy sources is possible via thermal energy storage (TES) systems which use phase change materials (PCMs) to store energy. PCMs store and release a large amount of energy in terms of their high melting heat. This study considered paraffin as PCM within the porous carbon matrix and copper oxide (CuO) as the nanoparticles (NPs). The molecular dynamics (MD) simulation method studied the simulated structure's phase transition process. The effect of atomic porosity and the initial pressure (IP) was considered and used in the atomic samples to survey the studied structure's thermal performance (TP). For this purpose, the changes in the charge time, discharge time, heat flux (HF), and phase transition time (PTT) were studied. The temperature and the total energy (TE) converged to 300 K and-1580 eV after 5 ns. It indicated that the defined matrix was physically stable. The increase in porosity from 1 % to 3 % increased HF from 1452 to 1642 W/m2 and decreased PTT from 3.92 to 3.73 ns. But, a further increase in porosity reduced the TP of simulated samples. On the other hand, the results show that the simulated atomic structure's TP was reduced by increasing the IP. HF decreased from 1452 to 987 W/m2 (1 to 5 % range), and the PTT increased from 3.92 to 4.05 ns (1 to 3 % range).

Automated summary

This study explores the use of phase change materials (PCMs) in thermal energy storage (TES) systems for renewable energy. The study focuses on the use of paraffin as PCM and copper oxide nanoparticles in a porous carbon matrix. Molecular dynamics simulation is used to study the phase transition process and the effects of atomic porosity and initial pressure on thermal performance.