Experimental investigation of a two-stage solar humidification–dehumidification desalination process

• A multistage HD process was investigated to improve efficiency of HD desalinator.
• 2-Stage process is the best choice from cost and performance point of view.
• A 2-stage solar HD desalination unit constructed and tested in an arid area
• Production is presented and compared during hot and cold days.
• Improvement in productivity and reduction of solar collector area were obtained.

This paper experimentally evaluates a two-stage technique to improve the humidification–dehumidification process in fresh water production from brackish water. According to modeling results of multi-stage process and on the basis of construction cost estimation, using a two-stage process is the most suitable choice that can improve important parameters such as specific energy consumption, productivity and daily production per solar collector area and thus, investment cost. A pilot plant was designed and constructed in an arid area with 80 m2 solar collector area to evaluate the two-stage process. This unit was tested on cold and hot days. The effect of main parameters on fresh water production of the unit is studied. Experimental results show that two-stage HD desalination unit can increase heat recovery in condensers and hence, reduce thermal energy consumption and investment cost of the unit. Moreover, productivity can be increased by 20% compared with the single-stage unit.