https://orcid.org/0000-0002-5103-0870
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ABSTRACT
In recent times, the thermochemical energy storage (TCES) method is gaining prominence due to its high energy storage density and minimal heat losses compared to the conventional thermal energy storage (TES) methods. This paper presents the cyclability behavior of selected zeolites for the TCES applications. The zeolites were subjected to sequential desorption and adsorption processes for five times using a differential thermogravimetric analyzer (DTG-60H). To investigate their suitability for the commonly available sources of thermal energy (e.g. solar energy, industrial waste heat), the samples were heated up to 150°C. These zeolites were also tested on Brunauer–Emmet–Teller (BET) analyzer for total surface areas and pore volumes, thus to read their sorption behavior. A field emission scanning electron microscope (FESEM) equipped with an energy dispersive X-ray (EDX) analyzer was used to examine the surface morphology and elemental composition of zeolite sorbents before and after the multi-cycle test run. The changes in the mass of a material during a process, either desorption or adsorption, were notably almost the same across the cycles tested, which confirms the cyclability of the materials tested. Amongst the tested materials, Zeolite-NaY and Zeolite-HY exhibited relatively better process enthalpies owing to their active water adsorption capacities. Of the six materials tested, Zeolite-NaY has offered better results and its enthalpies range from 287.5 J g−1 to 348.5 J g−1 for the desorption and from 81 J g−1 to 292.1 J g−1 for the adsorption. A mass gain was noticed for each of the tested materials as they undergo the cooling process, thus affecting water vapor adsorption capacity negatively.
Acknowledgments
The authors are grateful to the Central Analytical Labs at Hyderabad Campus, BITS-Pilani, and College of Technology, Osmania University, Hyderabad for granting permission to use their facilities. The authors also express special thanks to Prof. Ramakrishnan Ganesan, Department of Chemistry, Hyderabad Campus, BITS-Pilani for his valuable suggestions on the experiments.
Conflicts of interest
The authors declare that they have no conflict of interest.
Additional information
Notes on contributors
Ankammarao Padamurthy
Ankammarao Padamurthy is presently a Ph.D. scholar in the Mechanical Engineering department, BITS-Pilani, Hyderabad Campus, INDIA. His research interests are thermochemical materials and thermochemical energy storage systems.
Jalaiah Nandanavanam
Jalaiah Nandanavanam is faculty in the department of Mechanical Engineering, BITS-Pilani, Hyderabad Campus, INDIA. His research interests are thermodynamics and heat transfer, fluid dynamics and computational fluid dynamics, nano and composite materials and thermochemical energy storage systems.
Parameshwaran Rajagopalan
Parameshwaran Rajagopalan is faculty in the department of Mechanical Engineering, BITS-Pilani, Hyderabad Campus, INDIA. His research interests are thermal energy storage technologies, nanomaterials and nanoscale heat transport, biomaterials and composites, materials for energy efficient and sustainable buildings and artificial intelligence.