Thermal conductivity and phase change characteristics of hierarchical porous diamond/erythritol composite phase change materials

Highlights: • A new type of hierarchical porous diamond/erythritol composite PCM was proposed. • The thermal conductivity of the composite is 207% higher than that of erythritol. • Hierarchical porous diamond is favorable for mass transfer and leakage prevention. Erythritol as a phase change material (PCM) has the advantage of extremely high latent heat, excellent thermal stability. However, its low thermal conductivity and easy leakage greatly limit its practical application, so the development of novel shape-stabilized PCM with high thermal conductivity is of great significance. In this paper, thermal conductivity, melting point and adsorption properties of hierarchical porous diamond/erythritol composite PCM were calculated using molecular dynamics simulation. When the load of erythritol is 12.91 wt%, the thermal conductivity can reach 2.06 W ⋅m⁻¹K⁻¹, which is 207% higher than that of pure erythritol. The phonon vibration of erythritol plays an important role in the composite. Erythritol enhanced the mass transfer and shared part of the heat flux, which acted as an auxiliary heat channel. With the increase of load, the melting point increased and tended to bulk erythritol. The flexibility of erythritol in confined space was better, resulting in lower melting point than that in free space. The advantage of hierarchical porous diamond was verified by calculating centroid position of erythritol and interaction energy between host and guest. Significantly, the meso pore is conducive to heat and mass transfer, and the micro pore has stronger interaction with the core material.