Study of the effect of phase state on the interfacial thermal conductance between PCMs and ceramic skeletons

Composite phase change materials with sugar alcohol as the phase change material and highly thermally conductive ceramics as the porous skeleton are widely used in various thermal storage systems. The interfacial thermal conductance (ITC) between the phase change materials under different phases and the skeleton is an important factor affecting the rate of heat storage (release) in thermal storage systems. The ITC between ceramics(AlN, SiC) and sugar alcohols (mannitol and galactitol) in the solid and liquid states is investigated by means of both time-domain thermoreflectance and molecular dynamics simulations. The results show that the ITC between phase change materials and ceramic is better in liquid state than in solid state, and that the ITC between mannitol and ceramic is better, and that the ITC betweenAlN and sugar alcohol is better. More low-frequency phonons are involved in the thermal transport of the sugar alcohols in the liquid state, with an average overlap energy of about 9.5% higher than that of the solid state and an average phonon participation rate of about 6.8% higher. It was also found that it isthe H atom in the sugar alcohol that is linked to the C atom that governs the ITC.