Critical review on measured phase transition enthalpies of salt hydrates in the context of solid-liquid phase change materials

During the last decades, salt hydrates have become increasingly popular in research on phase change materials (PCM) due to their generally higher phase transition enthalpies and lower costs compared to organic PCM. However, in most published reviews on phase transition enthalpies of salt hydrates, the data stems from earlier data collections and the original experimental sources are often not mentioned. Therefore, a review on original experimental phase transition enthalpies of selected salt hydrates based on chlorides, hydroxides, and nitrates as well as some other materials popular in PCM literature is provided here. Additionally, information on the preparation process of the samples is contained along with the used calorimeter. This information helps to assess the experimental results especially for salt hydrates where considerable deviations for the phase transition enthalpies exist in literature. Even though salt hydrates are heterogeneous materials, the collected data shows that it is possible to obtain reliable values for their phase transition enthalpies via differential scanning calorimetry (DSC), but only under certain conditions.