Interfacial Heat Transfer Between Erythritol and Xylitol Crystals As a Mixture Heat Storage Material

The binary eutectic mixtures of sugar alcohols, which can maintain their high latent heat of fusion while extending the range of melting points for more flexible utilizations, have attracted increased attention. The eutectic mixture of erythritol and xylitol, with a melting point of 82 °C and a latent heat of fusion of 270 kJ/kg, has been identified as a promising latent heat storage material at the temperature range around 80 °C. In comparison to the pure components, the changes in thermal conductivity of mixture sugar alcohols are of great interest, which are investigated in this work with emphasis on the interfacial heat transfer across erythritol and xylitol molecules. Molecular dynamics simulations were performed to study the nanoscale heat transfer over an artificial interface between two crystal layers of erythritol and xylitol in contact with each other. Based on the non-equilibrium molecular dynamics method and eHEX algorithm, a constant heat flux was imposed over the simulated box. The dependence of the erythritol-xylitol interfacial thermal resistance on the system length was studied by adapting different system lengths. With increasing the length from 26 to 78 Å, the interfacial thermal resistance was predicted to decrease from 5.5 × 10⁻¹⁰ to 3.8 × 10⁻¹⁰ m²·K/W, which then becomes nearly unvaried while further increasing the system length to over 100 nm. The knowledge on the interfacial thermal resistance will help understand the changes in thermal conductivity of bulk mixtures of sugar alcohols.