Caesium doping accelerates the hydration rate of potassium carbonate in thermal energy storage

Potassium carbonate has recently been identified as a promising candidate for thermochemical energy storage. However, as for many salt hydrates, its reaction kinetics is relatively slow. KCO has a metastable zone, where the reaction is kinetically hindered, which limits the temperature operating window. This work aims to improve the material...

Diffusion limited hydration kinetics of millimeter sized salt hydrate particles for thermochemical heat storage

Potassium carbonate is a promising salt for thermochemical heat storage. For an application mm-sized salt hydrate particles are manufactured to be loaded inside a reactor. The step towards larger particles is necessary to prevent a large pressure drop over the reactor bed during hydration/dehydration in a given air flow. Therefore, in this work...

Encapsulation of Salt Hydrates by Polymer Coatings for Low-Temperature Heat Storage Applications

Efficient and cheap storage of energy from renewable resources presents a key technology to facilitate the ongoing energy transition. Storing heat in thermochemical materials (TCMs), such as salt hydrates, provides a promising concept to meet this demand. TCMs can capture heat reversibly and loss-free by relying on equilibrium hydration...

K2CO3 in closed heat storage systems

Potassium carbonate, K2CO3, has been identified as one of the most promising thermochemical storagematerials for the built environment. Where a lot of knowledge has been gained on hydration/dehydrationbehavior at atmospheric (open system) conditions, little is known of this process under pure water vaporconditions (closed vacuum system). In this...

Trouton's rule for vapor sorption in solids

Hygroscopic salts exhibiting fast and reversible hydration are promising systems for seasonal heat storage, providing the possibility of storing excess solar energy from the warm season for later use during the cold season. For heat storage, the salt is dehydrated with the available heat, and for heat recovery, the salt is rehydrated. There are...

Thermochemical Heat Storage: From Reaction Storage Density to System Storage Density

Long-term and compact storage of solar energy is crucial for the eventual transition to a 100% renewable energy economy. For this, thermochemical materials provide a promising solution. The compactness of a long-term storage system is determined by the thermochemical reaction, operating conditions, and system implementation with the necessary...

Thermophysical characterization and thermal cycling stability of two TCM: CaCl2 and zeolite

At this moment, the global energy consumption in buildings is around 40% of the total energy consumption in developed countries. Thermal energy storage (TES) is presented as one way to address this energy-related problem proposing an alternative to reduce the gap between energy supply and energy demand. One way to store energy is using...

Thermochemical heat storage - system design issues

Thermochemical materials (TCMs) are a promising solution for seasonal heat storage, providing the possibility to store excess solar energy from the warm season for later use during the cold season, and with that all year long sustainable energy. With our fixed bed, vacuum reactors using zeolite as TCM, we recently demonstrated long-term heat...

Experimental results of a 3 k Wh thermochemical heat storage module for space heating application

A 3 kWh thermochemical heat storage (TCS) module was built as part of an all-in house system implementation focusing on space heating application at a temperature level of 40 ºC and a temperature lift of 20 K. It has been tested and measurements showed a maximum water circuit temperature span (released by adsorption) of 20 – 51 K which is by all...

Thermophysical characterization of sorption TCM

Thermochemical materials (TCM) are proposed for thermal energy storage as one of the future options to achieve lower energy consumption in buildings and other industrial applications, as well as to store energy from solar energy. In this study, the thermophysical properties of two TCM, CaCl2 and zeolite, are determined with TGA and DSC and...

A review on the properties of salt hydrates for thermochemical storage

Solar energy is capable of supplying enough energy to answer the total demand of energy in dwellings. However, because of the discrepancy between energy supply and energy demand, an efficient way of storing thermal energy is crucial. Thermochemical storage of heat in salt hydrates provides an efficient and compact way of storing solar energy....

Design of a modular 3 kWh thermochemical heat storage system for space heating application