Latent Thermal Storage for Solar Cooling Applications: Materials Characterization and Numerical Optimization of Finned Storage Configurations

ABSTRACT

The present paper presents the development of a thermal energy storage system for application with non-concentrating solar plants using phase change materials (PCMs). The outcomes of an experimental analysis on commercial PCMs and laboratory-grade chemical compounds suitable for latent heat storages in a temperature range of 80–100°C is presented, with main focus on to the enthalpy and the cycle stability of the materials. Particularly, a first evaluation of possible degradation mechanisms in hydrated salts was investigated by means of nuclear magnetic resonance spectroscopy. The best performing materials have been implemented in a numerical model, based on the enthalpy method, used for the design of a thermal storage system. The configuration of the system, starting from a simple shell-and-tube layout, has been optimized by inserting asymmetric fin-and-tubes and the results with two selected materials have been compared. The analysis has shown that the most promising materials are the commercial ones belonging to the classes of paraffinic materials and hydrated salts and that, with the designed configuration, it is possible to store up to 200 kJ/m³ and get a peak power during discharge of about 1.5 kW.

Acknowledgments

The present work has been partially funded by PON “Ricerca e Competitività 2007–13” PON03PE_00206_2 S5 – Smart Small Scale Solar Systems. Prof. Marco Geppi from Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Italy, is kindly acknowledged for giving access to Solid State NMR instrumentation

Additional information

Notes on contributors

Valeria Palomba

Valeria Palomba graduated in Materials Engineering at the University of Messina in 2012 and holds a PhD in Engineering and Chemistry of Materials and Structures at the University of Messina. She is currently holding a research grant at CNR-ITAE. Her scientific activity is mainly focused on the development, through design and testing, of components for thermally driven systems and heat storages. She has co-authored 30 papers in international journals and conference proceedings.

Vincenza Brancato

Vincenza Brancato is a post-doc researcher at CNR – ITAE of Messina. She studied Materials Engineering at University of Messina and took her bachelor's degree in 2009. In 2012 she received her PhD in Chemistry and Engineering of Materials from the same university. Prior to joining CNR ITAE, she received a student fellowship at CNR IMM of Catania, during which she studied microscopic and electrical characterization techniques of materials used in solar cells. Her research interests include: materials for energetic applications and materials for storage and transformation of thermal energy. She has co-authored 26 papers in international journals and conference proceedings.

Giulia Palomba

Giulia Palomba is a PhD student in Engineering and Chemistry of Materials and Structures at the University of Messina. She obtained her Bachelor's degree in Industrial Engineering in 2015 and her Master's Degree in Mechanical Engineering in 2017 from the University of Messina. Her Bachelor thesis was focused on the characterization of PCM and multiphysics simulation.

Silvia Borsacchi

Silvia Borsacchi is a researcher at the Italian National Council of Research- Institute for the Chemistry of OrganoMetallic Compounds (CNR – ICCOM) – Pisa, Italy. She holds a PhD in Chemical Sciences from the University of Pisa, where she was a Post-Doc researcher before joining CNR. Her research specialty is the Solid State NMR spectroscopy of materials, on which she coauthored 45 papers on international scientific journals, several chapters in books and more than 100 communications at conferences.

Claudia Forte

Claudia Forte is a senior researcher at the Institute of the Chemistry of Organometallic Compounds of the Italian National Research Council. She received her PhD in Chemistry from the University of Pisa in 1987. She studied at the University of Pisa and at the Scuola Normale Superiore in Pisa where she obtained her MS degree in chemistry in 1982. Her research activity is focused on the application of solution and solid state NMR techniques for the investigation of the structural and dynamic properties of complex materials of interest for biomedical, environmental and technological applications. She is co-author of more than 100 publications on international peer-reviewed journals and over 200 contributions to international conferences.

Angelo Freni

Angelo Freni is a researcher at the Italian National Council of Research- Institute for the Chemistry of OrganoMetallic Compounds (CNR – ICCOM) – Pisa, Italy. Prior to joining CNR-ICCOM, he worked at the Institute for Advanced Energy Technologies (CNR-ITAE) – Messina, Italy. He holds a PhD in Materials and Chemical engineering from the University of Messina. His scientific interest concerns the field of energy technologies with special regard to thermally driven heat pumps, heat storage and hydrogen storage systems. He has co-authored more than 150 papers in international journals and conference proceedings.

Andrea Frazzica

Andrea Frazzica graduated in Materials Engineering at the University of Messina, Italy, in 2008 and completed his PhD in Chemical and Materials Engineering at the University of Messina in 2012. Currently he is working as researcher at CNR-ITAE, Institute for Advanced Energy Technologies, Messina. His scientific activity is mainly focused on the development and characterization of adsorbent materials and components for thermally driven heat pumps and on advanced materials, components and systems for thermal energy storage. He has published more than 60 printed papers on international journals and conference proceedings.