Abstract
The lack of robust and low-cost sorbent materials still represents a formidable technological barrier for long-term storage of (renewable) thermal energy and more generally for Adsorptive Heat Transformations—AHT. In this work, we introduce a novel approach for synthesizing cement-based composite sorbent materials. In fact, considering the number of available hygrosopic salts that can be accommodated into a cementitious matrix—whose morphological properties can be also fine-tuned—the new proposed in situ synthesis paves the way to the generation of an entire new class of possible sorbents for AHT. Here, solely focusing on magnesium sulfate in a class G cement matrix, we show preliminary morphological, mechanical and calorimetric characterization of sub-optimal material samples. Our analysis enables us to theoretically estimate one of the most important figures of merit for the considered applications, namely the energy density which was found to range within 0.088–0.2 GJ/m3 (for the best tested sample) under reasonable operating conditions for space heating applications and temperate climate. The above estimates are found to be lower than other composite materials in the literature. Nonetheless, although no special material optimization has been implemented, our samples already compare favourably with most of the known materials in terms of specific cost of stored energy. Finally, an interesting aspect is found in the ageing tests under water sorption-desorption cycling, where a negligible variation in the adsorption capability is demonstrated after over one-hundred cycles.
Highlights
The lack of robust and low-cost sorbent materials still represents a formidable technological barrier for long-term storage of thermal energy and more generally for Adsorptive Heat Transformations—AHT
Approaches, the use of cement-based host matrices enables to both fine tune porosity and to introduce an innovative in situ synthesis
The new in situ synthesis proposed in this study aims at a direct production of sorbents by properly mixing the cement paste with a salt-containing aqueous solution
Summary
The lack of robust and low-cost sorbent materials still represents a formidable technological barrier for long-term storage of (renewable) thermal energy and more generally for Adsorptive Heat Transformations—AHT. Thermochemical and sorption based energy storage has attracted much attention in the scientific community due to a strong potential to achieve large energy density combined to negligible losses even for long-term applications. Salt hydrates are largely studied for their high energy density They are prone to deliquescence and cracks formation leading to low cyclability. Solid microporous sorbents, Scientific Reports | (2020) 10:12833 Such as zeolites or silica gels, are characterized by a high level of hydrothermal stability, with higher power outputs and cyclability, at the expenses of lower energy densities and higher c ost[5,6,7]. The matrix porosity must not be filled completely with the active material, otherwise the water vapour flow reveals problematic and the solution formed inside the pores can leak out due to the volume expansion[9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
