Theoretical and experimental investigation of the performance of adsorption heat storage system

摘要

Theoretical and experimental investigation of the thermal energy storage of an open adsorption system is presented. The theoretical model describes the mass and energy transfers in the system. The coupled energy and mass balance equations have been solved using the COMSOL (TM) software. The model was validated against laboratory experiments performed at varying conditions using AA13X as well as silica gel as adsorbent. Laboratory experiments have been conducted to study the effect of flow rate and inlet relative humidity on the amount of energy stored. Temperature and energy density profiles during the adsorption process have been obtained and analyzed for various conditions. Results showed that there is a trade-off between released energy and temperature output and an optimization is recommended before choosing the operating flow rate. It was found that a flow rate of 21 m(3)/hr has the best performance for a bed volume of 5. 09 x 10(-4) m(3). Furthermore, the results show that the storage density increases with the increase of the air inlet relative humidity. For the predefined working conditions and assumptions, the numerical solution shows satisfied agreement with the experimental measurements. A parametric study was performed using silica gel as adsorbent to predict the behavior of the thermal energy storage system for varying operating conditions and parameters. The studied parameters include the system flow rate, relative humidity, regeneration temperature, and the particle diameter. It was found that a flow rate of 0.7 m(3)/min, regeneration temperature of 95 degrees C and average particle diameter of 1.0 mm gave the best performance for the bed with a volume of 1.57 x 10(-3) m(3).