Efficiency Analysis of An Integrated Cascade Sorption Energy Storage into A Solar DHW System
Abstract
Sorption heat storage has garnered significant interest for its potential in long-term thermal energy storage, particularly in domestic hot water (DHW) systems. This paper explores the concepts and operating principles of single material and cascade thermochemical energy storage systems, focusing on their application in solar DHW production. Single material sorption systems store and release energy based on reversible physicochemical phenomena, while cascade systems utilize two different storage materials to optimize energy density and discharge temperature. The study assesses and compares the integration of salt-hydrates-based cascade sorption energy storage, specifically using MgCl₂·6H₂O and SrBr₂·6H₂O, with a solar DHW system for a single-family dwelling in the distinct climates of Coimbra (Portugal) and Shiraz (Iran). The findings indicate that the cascade system can result in a 21% and 43% reduction in auxiliary energy demand respectively in Coimbra and Shiraz, thus significantly increasing the renewable energy share and enhancing energy efficiency in DHW systems.