Thermochemical energy storage - experimental investigation of the discharging process in a suspension reactor with a special focus on K2CO3

Abstract

Climate change and the recently added gas crisis require research and rapid implementation of new technologies for energy production or effective energy storage. One very promising technology is the principle of thermochemical energy storage. Here, surplus industrial waste heat or, quite simply, heat in the summer is used. The heat is stored in a storage system using a reversible reaction and released again when required by adding water. The advantages of this approach are the high storage densities as well as low thermal losses.In this work, the focus is on the investigation of the systems calcium chloride, copper sulfate, and potassium carbonate.The main part of this work deals with experiments to avoid agglomeration in the promising salt potassium carbonate. Potassium carbonate does not agglomerate when pure silicone oil is used as the suspension medium, but very strong agglomeration is observed when pure mineral oil is used. However, pure silicone oil is too expensive to be considered for industrial scale. Therefore, the first approach was to optimize oil mixing ratios and subsequently perform experiments with surface-treated particles up to the first coating experiments. In addition, the enthalpy of reaction was determined and the resilience of the individual methods was tested at low pressure. Furthermore, experiments were carried out at high pressure. For copper sulfate, the focus was on determining optimal conditions to obtain the highest possible reaction enthalpy and temperature rise. In addition, the influence of the rate concerning water addition was determined for all 3 systems.The results show that potassium carbonate in oil mixtures exhibits significantly lower agglomeration and that both the surface-treated particle experiments, as well as initial experiments on coating work without agglomeration, occur. Copper sulfate shows the highest enthalpy of reaction at high suspension temperature. The speed of water addition showed decisive influences only with the system potassium carbonate in pure silicone oil