Modeling and assessment of a thermochemical energy storage using salt hydrates

Summary Several research studies have revealed the potential use of salt hydrates in thermal energy storage applications. These materials dissociate into anhydrous salts and release water vapor when subjected to heat source. The latter salt has the capability to store the energy that was supplied for dehydration upon heating. This thermal energy can be extracted by flowing cooler water or water vapor through the salt to obtain sensible heat that can be exploited for several applications, such as heating residential buildings during cold seasons. In this study, a numerical model that describes the overall thermochemical process of salt hydrates when being heated is developed. In comparison with previous published studies, the main contribution of the present work is to account for the impact of the temperature on the thermodynamic properties of the system. The obtained results agree well qualitatively and quantitatively with their experimental counterparts. A comparative study between three different salt hydrates, namely, the magnesium sulfate  (MgSO 4  ∙ 7H 2 O) , the cupric sulfate ,(CuSO 4  ∙ 5H 2 O) , and the gypsum  (CaSO 4  ∙ 2H 2 O) , is conducted in order to investigate their capabilities to efficiently store thermochemical energy. The present performance analysis aims at identifying the proper salt hydrates for the intended applications. It is shown that the cupric sulfate enables the best performance in terms of efficiency (defined as the ratio of stored energy over the supplied energy), and it requires the minimum heating time to initiate the chemical reaction. Copyright © 2017 John Wiley & Sons, Ltd.