Characterization and thermophysical properties of erythritol/expanded graphite as phase change material for thermal energy storage

Abstract

The main aim of this paper is to enhance the thermal conductivity of erythritol as phase change material (PCM). The expanded graphite (EG, thermal conductivity: 151 W/(m•K)) is dispersed into erythritol (melting point: 118 °C, thermal conductivity: 0.844 W/(m•K)) as the high thermal conductivity additive, in which erythritol can be adsorbed effectively. The 2% EG/erythritol composite PCM has better cycle stability and its thermal conductivity enhances obviously. The 1% calcium pimelate (CaPi) is used as nucleating agent to inhibit the supercooling of the composite PCM further. The 2%EG/1%CaPi/erythritol composite PCM starts to solidify at 98.5 °C and the equilibrium temperature is about 115 °C during 100 cycles. The latent heat is 352.66 J/g and the thermal conductivity measured by the laser flash method is 1.287 W/(m•K), which is 52.5% higher than pure erythritol. Therefore, it is a new candidate to be used in waste heat recovery, solar energy medium temperature heat collection and other fields.