A continuous desalination system using humidification – dehumidification and a solar still with an evacuated solar water heater

• The different water mass flow rate on HDH is investigated.
• Enhancement of the gain output ratio of the desalination unit.
• Enhancing the thermal performance of the desalination unit with reusing rejected water from HDH.

A continuous solar still (SS) integrated with a solar humidification–dehumidification (HDH) is investigated. An evacuated solar water collector is utilized in the HDH. The idea of closed-air and open-water cycles is considered as the operating principle of HDH process. The different water mass flow rates (1.5, 2, 2.5 and 3 L/min) of HDH is investigated. To avoid a large water loss during HDH desalination, a SS is fed with the exit warm water from HDH during day and night time. Therefore, the productivity of the SS with exit warm water from HDH is greater than that of the conventional solar still (CSS) by approximately 242% and the gain output ratio (GOR) is increased by about 39%. The daily water productions of the CSS, SS with exit warm water from HDH, HDH unit and continuous solar desalination unit are 3.9, 13, 24 and 37 L/day, respectively.