Experimental study of CaO/Ca(OH)₂ in a fixed-bed reactor for thermochemical heat storage

Highlights: • A new approach (Li-doped Ca(OH)₂) is used to improve the heat storage process. • Air can seriously affect the heat release process in a fixed-bed test. • A lower initial sample temperature leads to a higher extent of the dehydration reaction. • A higher vapor pressure obviously improves the heat release capacity. - Abstract: The CaO/Ca(OH)₂ thermochemical heat storage system is a very promising method to realize solar thermal energy utilization and industrial waste heat recycling. In this study, a CaO/Ca(OH)₂ test-bed is setup to investigate the heat storage and release processes. In the heat storage process of pure Ca(OH)₂, a higher dehydration temperature results in a faster heat storage speed. In addition, the heat storage process of Li-doped Ca(OH)₂ can obtain a faster heat storage speed and produce more thermal energy than that of pure Ca(OH)₂. The results of the experiment show that the air can seriously affect the heat release process in a fixed-bed test. Therefore, the method of pumping out the air is used in this study to improve the heat release process. According to the results of the heat release experiment, a lower initial sample temperature can lead to a higher extent of the dehydration reaction. Furthermore, a higher vapor pressure obviously improves the heat release capacity.