Utilization of waste heat by means of an adsorptive heat storage system and simulation tools

Heat storage is an important aspect in many applications like heat recovery of waste heat from industrial process or in renewable energy plants. The principle of the adsorption storage system is based on a gaseous working fluid, e.g., water, which gets adsorbed by a highly porous material, e.g., zeolite. This adsorption process is an exothermal one. In order to recharge the heat storage system, desorption of the working fluid is done by heating the porous material. A thermochemical method was used with a reversible adsorption/desorption process in order to improve the heat transfer and storage density. Therefore, an experimental sorption unit has been set to measure the invested and stored heat in the adsorbent packed bed. In addition, simulations were performed in order to predict the optimal operating conditions of the system. This gives also the possibility to virtually add and remove components to the heat storage unit. Experiments were carried out to validate the heat storage model. The results have shown good comparison to the simulation, with an average deviation of 2.4 %. The simulations also indicated that by applying a multiple-reactor system, the invested heat can be reduced by 15 %.