Thermal Performance Assessment of PCM-Enhanced Solar Absorption Cooling Systems Under Various Operating Conditions in Morocco

Abstract

A transient numerical model was developed to assess a solar-driven single-effect H2O/LiBr absorption cooling system coupled to a stratified hot-water tank containing spherical PCM capsules. Following validation against published data, the model was applied under Moroccan climatic conditions to examine three PCMs with phase-transition temperatures of 60, 70 and 80 °C; volume fractions of 20–50%; Flat-Plate and Evacuated Tube Collectors; different collector areas and tank volumes; and three cooling demand profiles. Reference PCM-A (Na(CH3COO)·3H2O), with a transition temperature of 60 °C, exhibited the most suitable thermal response for the investigated operating range because its phase-change interval closely matched the tank temperatures, thereby maintaining suitable generator conditions and enabling transient coefficient of performance values near 0.70. A PCM volume fraction of 30% provided the most effective balance between latent heat storage and the sensible storage capacity of water. Under Marrakech summer conditions, PCM integration increased the solar fraction from 64% to 69%, 54% to 85% and 57% to 60% for the Morning, Evening and Day profiles, respectively. Annually, useful thermal energy increased from 12,353 to 12,456 MJ, whereas auxiliary electricity consumption decreased from 1820 to 1705 MJ (−6.3%). Among the configurations examined, combining Reference PCM-A at 30% with Evacuated Tube Collectors resulted in the most favourable overall performance, emphasizing the importance of matching the PCM transition range to the system operating temperatures.