Evaluating performance of desalination plant integrating absorption cycle, humidification-dehumidification system, and internal heat recovery process for sustainable water production
Ehab S. Ali, Ahmed S. Alsaman, K. Harby, Abdulrahman Alanezi, Ridha Ben Mansour, Rached Ben‐Mansour
Abstract
Freshwater scarcity and the utilization of low-grade thermal energy motivate this study. Conventional absorption desalination–cooling (ABDC) systems and humidification–dehumidification (HDH) units each face limited water productivity, highlighting a need for configurations that recover and cascade heat more effectively. The main objective of this study is to enhance water productivity and the utilization of low-grade thermal energy in the conventional absorption desalination-cooling (ABDC) plant. This study proposes unique combinations integrating the conventional absorption cycle, HR, and HDH desalination systems. Three novel configurations of ABDC integrating with the HDH desalination plant and with an internal HR scheme are presented, compared, and evaluated theoretically in this study. The internal heat recovery scheme is used between the evaporator and condenser of the absorption cycle. This enhances the condensation process in the condenser and the evaporator's evaporation process, thereby improving the water production of absorption plants. In the second configuration scheme, the seawater supplied to the humidification-dehumidification plant passes first to the absorber and condenser heat exchangers of the absorption cycle to absorb the heat of absorption and condensation. In addition, preheating the feed seawater before going into the humidification-dehumidification enhances the water evaporation rate in the humidifier, increasing the water production from the humidification-dehumidification plant. The second configuration delivers both cooling effects along with fresh water. In the third configuration, the absorption cycle with internal heat recovery is combined with the humidification-dehumidification plant to get only fresh water. Mathematical models are developed and then validated with data available from the literature to simulate the performance of the proposed configurations. Results demonstrated that the improvement of three configurations at 85 °C regeneration temperature for water production was 84, 128, and 197 %, while the improvement for the gain output ratio was 14, 128, and 84.3 %, respectively, more than a traditional absorption cycle. • Innovative internal heat recovery for absorption desalination is investigated. • Three novel absorption and humidification-dehumidification cycles are investigated. • The proposed combined system improves water production by 197 %. • The proposed combined system improves the gain output ratio by 128 %.