Thermophysical Characterization of MgCl(2)·6H(2)O, Xylitol and Erythritol as Phase Change Materials (PCM) for Latent Heat Thermal Energy Storage (LHTES)

The application range of existing real scale mobile thermal storage units with phase change materials (PCM) is restricted by the low phase change temperature of 58 [Formula: see text] for sodium acetate trihydrate, which is a commonly used storage material. Therefore, only low temperature heat sinks like swimming pools or greenhouses can be supplied. With increasing phase change temperatures, more applications like domestic heating or industrial process heat could be operated. The aim of this study is to find alternative PCM with phase change temperatures between 90 and 150 [Formula: see text]. Temperature dependent thermophysical properties like phase change temperatures and enthalpies, densities and thermal diffusivities are measured for the technical grade purity materials xylitol (C [Formula: see text] H [Formula: see text] O [Formula: see text]), erythritol (C [Formula: see text] H [Formula: see text] O [Formula: see text]) and magnesiumchloride hexahydrate (MCHH, MgCl [Formula: see text] [Formula: see text] 6H [Formula: see text] O). The sugar alcohols xylitol and erythritol indicate a large supercooling and different melting regimes. The salt hydrate MgCl [Formula: see text] [Formula: see text] 6H [Formula: see text] O seems to be a suitable candidate for practical applications. It has a melting temperature of 115.1 ± 0.1 [Formula: see text] and a phase change enthalpy of 166.9 ± 1.2 [Formula: see text] with only 2.8 [Formula: see text] supercooling at sample sizes of 100 [Formula: see text]. The PCM is stable over 500 repeated melting and solidification cycles at differential scanning calorimeter (DSC) scale with only small changes of the melting enthalpy and temperature.