Temperature dependence of thermophysical properties of polyethylene glycol in solid/liquid phase change region

Abstract

The knowledge of the thermophysical properties of phase change materials (PCMs) is of great importance in the design of thermal energy storage systems. In this work, several thermophysical properties of four PEGs with different molecular weights from 800 to 2000 were studied experimentally. Differential scanning calorimetry (DSC) was used to study the phase change temperatures and latent heat in the melting and crystallization processes of PEGs. The thermal conductivities of PEGs covering both solid and liquid phases were measured by a transient hot-wire thermometer at a temperature range from 283.15 to 353.15 K. Density and viscosity of liquid PEGs were determined by densimeter and viscometer, respectively. Phase change latent heat, thermal conductivity, and density increase with PEG molecular weight, which indicates that PEGs with higher molecular weight show better energy storage ability per volume. Phase change temperatures vary with molecular weight, so a wide range of operating temperatures can be satisfied using different molecular weight PEGs. Viscosity increases dramatically with PEGs molecular weight, so higher pump energy consumption is needed for larger PEG when it flows in the liquid phase. Furthermore, available literature data were used to compare with our results, our data agree well with most literature data.