Using Molding to Fabricate Stable Salt Structures for Thermochemical Energy Storage

The present work investigates using a molding technique to fabricate stable salt structures for thermochemical energy storage. Two type of salts were investigated: pure MgSO4 and a blend of 53% CaCl2 with 47% MgSO4. These salts were mixed with two common binders and hot pressed. Various post-hot-pressing conditions were considered including the debinding temperature, whether the sample was sintered, and the sintering temperature. The samples were subjected to combined hydration and thermal cycling. The hydration reaction was monitored by measuring the relative humidity. The samples were visibly inspected for changes between each half cycle. The results indicate that molding can result in stable structures. All the samples of 53wt%CaCl2+47%wtMgSO4 and one sample of pure MgSO4 retained their integrity through the course of cycling. Of the samples that did not retain their integrity through cycling, the results show that fabrication parameters can be used to improve the cycle stability of the molded sample. The hydration data shows that, for the samples that retained their structure, stable hydration rates were achieved. This indicates that the structure stabilized. These results show the feasibility of using molding or similar manufacturing techniques to fabricate a stable structure of hygroscopic salts for thermochemical-based, thermal energy storage.