A molecular dynamics-based study on the microstructural phase transition mechanisms of novel paraffin composite phase change materials

Abstract

The thermodynamic mechanisms and properties of paraffin-based composite phase change materials at microscopic scale directly influence their potential applications in energy storage and conversion. This study employs molecular dynamics simulations to construct two models of composite phase change materials. Both experimental and simulation results demonstrate that, compared to two pure alkanes (n-octadecane and n-eicosane), thermal conductivity increases from 0.14 W/(m·K) to 0.31 W/(m·K) for the MOT (n-octadecane mixed with glycerol trimyristate) system and from 0.13 W/(m·K) to 0.27 W/(m·K) for the MET(n-eicosane mixed with glycerol trimyristate) system, indicating a twofold increase. Further investigation into thermodynamic properties, such as van der Waals energy, phase change temperature, and specific heat capacity, reveals microscopic interactions governing the phase transitions in the two binary composite systems. These findings enhance understanding of the molecular structural mechanisms during the phase change process in composite phase change material systems.