https://pure.tue.nl/ws/files/51662523/1_s2.0_S0306261916319316_main.pdf

Sorption heat storage for long-term low-temperature applications: A review on the advancements at material and prototype scale

A viable way to manage the inherently intermittent availability of solar energy in concentrated solar power plants is to store solar energy during on-sun hours to be able to use it later during off-sun hours, enabling on-demand electricity delivery. Thermochemical heat storage systems present some noteworthy advantages when compared with latent and sensible heat storage, namely (i) high energy storage density because the storage capacity by unit of mass or volume corresponding to the reaction enthalpy is generally high, (ii) heat storage at room temperature and long term energy storage because the products can be cooled and stored at room temperature without energy losses as heat can be stored indefinitely in chemical bonds, (iii) facility of transport because solid materials can be transferred over long distances, (iv) constant restitution temperature providing constant heat source because exothermic reactions are carried out at sufficiently high temperatures to generate electricity in constant conditions and therefore to produce a constant power. This paper presents an overview of the different potential thermochemical systems based on reversible solid-gas reactions operating at high temperatures and a screening of suitable materials that are interesting candidates in the 400–1200 °C range for thermochemical heat storage in concentrated solar power systems. The most promising materials belonging to the metal oxides, hydroxides, and carbonates solid-gas systems are selected for experimental validation and further investigations.

Screening of thermochemical systems based on solid-gas reversible reactions for high temperature solar thermal energy storage

https://pure.tue.nl/ws/files/65069212/1_s2.0_S0306261917304750_main.pdf

A review of salt hydrates for seasonal heat storage in domestic applications

Development and thermochemical characterizations of vermiculite/SrBr2 composite sorbents for low-temperature heat storage

Salt hydrates have promising potential as heat storage materials by use of their hydration/dehydration reaction. These hydration/dehydration reactions are studied in this paper for CuCl2, CuSO4, MgCl2 and MgSO4. During a hydration/dehydration reaction, the salt shrinks and expands as a result of the differences in densities of the phases. As a result, after the first dehydration cycle, the crystal is fractured into a pseudomorphic state that releases the water molecules more easily. The effect of fracturing is larger in case of hydrates with larger volumetric changes. In this study the performance of hydrates during cyclic loading is related to the pore water production and volume variations. On the basis of such data, it is concluded that CuCl2 is the most promising heat storage material. © 2015.

https://pure.tue.nl/ws/files/20527854/1_s2.0_S2352152X1530027X_main.pdf

Experimental studies for the cyclability of salt hydrates for thermochemical heat storage

Experimental Studies of the Mechanism and Kinetics of Hydration Reactions

Thermochemical investigation of the water uptake behavior of MgSO4 hydrates in host materials with different pore size

The mechanism and the kinetics of hydration reactions are important for the application of a salt hydrate as a thermochemical heat storage material. MgSO4∙H2O and Na2SO4 were chosen in this study because they are both promising candidates for such an a pplication. Considering that the hydration of these salts yields MgSO4∙7H2O and Na2SO4∙10H2O as the reaction products, the maximum overall heat effect can be calculated from the heat of condensation of water vapor (44 kJ mol –1 ) and the heats of hydration of 75 kJ∙mol -1 (for MgSO4∙H2O) and 81 kJ mol -1 (for Na2SO4). Based on the densities of the two hydrated phases, this results in the very high theoretical energy densities of 2.3 GJ·m -3 and 2.4 GJ·m -3 , respectively, for MgSO4∙7H2O and Na2SO4∙10H2O. Not only the energy density is important for the dimensioning of a storage system, but also the kinetics of h ydration reactions play a major role for the application as storage material. In the present study, hydration reactions under varying climatic conditions were investigated by using water vapor sorption measurements and in-situ Raman microscopy. Using t he phase diagrams, it can be clearly shown that the mechanism and the kinetics depend on the climatic conditions. Below the deliquescence humidity of the lower hydrated phase the hydration proceeds as solid state reaction, whilst above the deliquescence humidity a through solution mechanism takes place.

SHC 2013, International Conference on Solar Heating and Cooling for Buildings and Industry September 23-25, 2013, Freiburg, Germany Experimental studies of the mechanism and kinetics of hydration reactions

Michael Niermann

Papers

Experimental Studies of the Mechanism and Kinetics of Hydration Reactions

Thermochemical investigation of the water uptake behavior of MgSO4 hydrates in host materials with different pore size

SHC 2013, International Conference on Solar Heating and Cooling for Buildings and Industry September 23-25, 2013, Freiburg, Germany Experimental studies of the mechanism and kinetics of hydration reactions