We are pleased to announce that Marie Gollsch, researcher at the Institute of Engineering Thermodynamics of the German Aerospace Center (DLR), will give the SFB 1313 "Pretty Porous Science Lecture" #50. Her talk will be on "Thermochemical energy storage: Experimental investigations on structural changes of CaO/Ca(OH)2 bulks".
Date: Thursday, 29 February 2024
Time: 4:00 pm CET
Speaker: Dipl.-Ing. Marie Gollsch (DLR)
Lecture title: "Thermochemical energy storage: Experimental investigations on structural changes of CaO/Ca(OH)2 bulks"
Place: Multi Media Lab (MML), U1.003, Pfaffenwaldring 61, 70569 Stuttgart, Campus Vaihingen. If you are interested in participating in the lecture, please contact edward.coltman@iws.uni-stuttgart.de
Remote Access: (Webex Access)
Abstract
Storage of thermal energy has the potential to become a major part of future energy systems due to versatile integration possibilities as well as relatively low cost. Thermochemical energy storage (TCS), in which thermal energy is stored as chemical potential, is particularly promising for certain applications such as long-term energy storage and thermal upgrade of waste heat. However, this technology still requires considerable efforts in research and development in order to deliver market-ready solutions.
The presented work investigates a widely recognised factor that is a major obstacle to the technical implementation of TCS based on chemical reactions: As the TCS materials react during charging and discharging of the storage, they change their chemical composition and thus their chemical and physical properties. In case of gas-solid reaction systems, which represent a majority of the materials studied, the changes in solid morphology can be significant, leading to correlating changes in any related properties of the storage material, often in the order of magnitudes. Design and predictive modelling of reactors and storage systems are therefore challenging.
To improve the knowledge of the relevant processes leading to changes in reaction and transport behaviour within TCS material bulks, the reaction system CaO/Ca(OH)2 is studied in depth as challenges caused by restructuring of this system's solids are widely reported in literature.
In this work, bulk storage materials consisting of powder, nanoparticle-modified powder, shaped and encapsulated granules are investigated over the course of several reaction cycles. Changes in gas permeability and thermal conductivity are discussed qualitatively and – where feasible – quantitatively. Additional analyses are carried out with regard to reactivity, morphology and phase composition. In summary, it is concluded that the inhomogeneities that develop within the reaction beds are likely to be so pronounced that they can lead to reaction temperature variations in the range of tens of Kelvin within a distance of centimetres. Further studies on the microstructure development of the reacting storage materials are identified as very promising to further TCS technologies. Based on the results regarding material tailoring, a combination of the studied approaches is proposed. Shaped materials such as granules with diameters in the range of a few millimetres are promising to prevent material agglomeration and improve material handling while minimising limitations due insufficient heat and mass transfer. Mechanical stabilisation is possible either through a “breathing” nanocoating or by an inert fraction within the particle. The presentation concludes with an outlook on the demonstration of this approach on a technical scale and on the ongoing investigations into the microstructure of reacting TCS materials.
About the presenter
Dipl.-Ing. Marie Gollsch is a staff researcher at the Institute of Engineering Thermodynamics of the German Aerospace Center (DLR) in Stuttgart.