Experimental and theoretical study on a heat pump driven open-air humidification dehumidification desalination system

This article presents experimental and theoretical investigations of a new configuration of an open-air open-water (OAOW), water-heated (WH), humidification-dehumidification (HDH) desalination system coupled with a vapor compression heat pump (HP) that considers two possibilities of energy recovery. Three different HDH system configurations including the basic system HDH-HP (without brine energy recovery), system A (basic system with brine energy recovery for pre-heating saline water), and system B (basic system with brine energy recovery for pre-heating ambient air) are presented. The performance of the basic system is examined experimentally; while that of systems A and B are assessed theoretically. Furthermore, the theoretical analysis is extended to the basis system to address the boundaries, constraints and limitations of experimental equipment, by analyzing the system performance at extended operation conditions. Results reveal that the developed model shows a good agreement against the experimental findings. Results also show that systems A and B portrayed superior performance over the basic system (especially system A), due to the energy recovery from the rejected brine. A maximum GOR of 2.72, RR of 2.56%, water productivity of 9.23 kg/h and a minimum freshwater cost of 15.14$/m³ are attained experimentally, while theoretical results for system A revealed a maximum GOR of 5.06, RR of 3.98%, water productivity of 11.46 kg/h, and a minimum price of freshwater of 12.38$/m³.