Findings on thickening Glauber’s salt

Glauber’s salt (sodium sulfate decahydrate, SSD) has long drawn attention as a Phase Change Material (PCM) for latent heat storages because of its high enthalpy of fusion, density and melting point, suitable for space heating. Unfortunately, Glauber’s salt exhibits several drawbacks such as supercooling and phase segregation after repeated cycles, the latter being responsible for its limited long-term stability. This work shows the attempts on thickening Glauber’s salt in order to overcome the separation tendency of inherent solid particles due to the limited solubility of sodium sulfate in the water of crystallization. Different thickening/gelling agents and combinations thereof have been applied and evaluated. The long-term stability was assessed through thermal cycling and optical evaluation of the samples. Thermo-physical properties were measured through Differential Scanning Calorimetry (DSC) allowing to estimate the degradation of enthalpy through addition of thickeners. Suitability of different thickeners with regard to effectiveness and conservation of thermo-physical properties are discussed.