WEB Bulk-scale Testing of Pelletized SAPO-34 for Water Adsorption-based Thermal Energy Storage
The reversible process of water vapour adsorption on a porous adsorbent material is promising for long-term thermal energy storage and other heat transformation applications. SAPO-34 is a highly structured microporous silicoaluminophosphate that displays many favourable characteristics for thermal energy storage and heat transformations, such as relatively low temperature required for regeneration, an S-shaped water-adsorption isotherm, and high water-loading capacities.
In this study, using a binder, SAPO-34 powdered sample was pelletized into spherical particles. The pelletized sample was characterized using gravimetric, SEM, TEM, and PX-RD analysis. Approximately 50 g of the pelletized SAPO-34 was loaded into a packed bed column, then the energy storage performance was tested using a bulk-scale thermochemical energy storage apparatus. The effects of regeneration temperature, relative humidity, and column insulation were quantified with respect to energy storage performance variables such as energy storage density, temperature lift, rate of adsorption, and cyclic stability.
The presence of the binder reduced the amount of active material and therefore lowered its energy storage density. However, it was found that the pelletized SAPO-34 performed better than conventional materials like silica gel and zeolite 13X. The pelletized SAPO-34 had higher energy storage densities and temperature lifts. The sample also required lower regeneration temperatures and lower relative humidity levels. It also showed minimal degradation after multiple hydration and dehydration cycles. The results contained herein support that SAPO-34 has great potential for long-term thermal energy storage and various thermal energy transformation applications.