Unique properties of thermochemical materials and their impact on thermochemical systems
Thermal energy storage materials with superior thermophysical and thermochemical properties are important to develop efficient and cost effective thermal energy storage solutions, e.g. to increase waste recovery of industrial process heat, to improve the performance of combined heat and power systems or even balance seasonal fluctuations of low grade heat demand. In addition to the primary aspect of thermal energy storage, thermochemical systems based on reversible gas-solid reactions offer unique characteristics in terms of storage duration, energy and power density, the possibility to upgrade thermal energy or to generate heat and cold on demand.
However, since these unique characteristics are directly related to the chemical reaction they are often accompanied by structural changes of the bulk material during cycling. These structural changes may have a severe impact on the necessary gas and heat transfer inside the reaction bed and therefore on the performance of a thermochemical system in general.
The presentation will outline exemplary thermochemical systems for different applications and discuss the various approaches to understand, to control or to handle these structural changes in laboratory prototypes. Based on these technical examples, the current state-of-the art of thermochemical materials will be discussed and relevant research and development aspects will be deduced.