Charging and discharging characteristics of absorption energy storage integrated with a solar driven double-effect absorption chiller for air conditioning applications

The operation of solar driven air conditioning systems is limited to the availability of solar radiation. Consequently, to achieve extended cooling period, energy storage is necessary. This study presents performance evaluation and charging and discharging characteristics of an absorption energy storage coupled with solar driven double-effect water-lithium bromide (H₂O-LiBr) absorption system through thermodynamic modeling and simulation. The absorption energy storage stores the solar heat in the form of chemical energy during the day and discharges later for cooling application. The integrated system achieved effective cooling for about fourteen hours on daily basis. The results indicate an average coefficient of performance (COP) of 1.35 for the integrated absorption chiller-storage unit and exergy efficiency of 25%. Furthermore, the overall COP of the integrated solar cooling system is 0.99 and the overall exergy efficiency is 6.8%, while the energy storage density for typical climatic conditions of Dhahran, Saudi Arabia is found to be 444.3 MJ/m³. The energy storage density obtained from the integrated solar driven H₂O-LiBr double-effect absorption system is found to be higher by 13–54% compared to other integrated systems based on single-effect configuration.