Epsomite dehydration: A molecular dynamics study

摘要

Salt hydrates such as epsomite (MgSO4 · 7H2O) has recently found potential applications in the area of seasonal energy storage systems due to its high energy storage density and wide availability. These materials can be used to store solar energy during summer and regenerate it during winter for room/water heating using reversible dehydration/hydration reaction. During dehydration, these materials undergo substantial changes in crystal structure, and it poses a problem with the reusability of the material. Here a molecular dynamics study is presented to understand the changes in crystal structure as a function of dehydration. Besides, the vacant fraction, RDFs are also studied as a function of dehydration. These results show that the dehydration is a diffusion limited process. The effect of hydrogen bonds on dehydration is also tested by switching off the hydrogen bond. The dehydration rates appear to be faster when hydrogen bonds are switched off proving the previous understanding that the hydrogen bonds slow down the dehydration kinetics in salts hydrates.