Extruded Water Adsorbent APO-Tric for Adsorption Thermal Battery Utilizing Solar Energy
Abstract
An adsorption thermal battery utilizes the reversible adsorption and desorption of water on porous solids and is of particular interest in combination with solar thermal collectors. The efficiency of this technology depends on the performance of the adsorbents, which should have high water adsorption capacity and, consequently, a high energy storage density, stability under humid conditions, and fast kinetics of adsorption and desorption. New synthetic approaches and improved performance of the adsorbents and the systems are being studied to improve the energy storage performance. The microporous aluminophosphate APO-Tric adsorbent with chabazite structure was shaped into extrudes and granules on laboratory scale, showing higher water adsorption capacity of the extrudes in comparison to the granules. The APO-Tric extrudes were tested in 15 adsorption-desorption cycles between 40 ⁰C and 90 ⁰C at a water vapour pressure of 12.5 mbar and showed good hydrothermal stability under these conditions. Good mass balances between adsorbed and desorbed water were achieved in the sorption cycles. In all cycles, maximum temperatures from 53 to 57 °C were reached during adsorption.