Direct contact membrane water distillation assisted with solar energy

• The effect of operating and geometric parameters on the unit performance was studied.
• Maximum productivity and daily efficiency reached 40.587 kg/day, 60.06%, respectively.
• Gain output ratio (GOR) reached 0.624.
• Membrane inner diameter should be higher than 2.5 mm to reduce pressure loss in membrane.

An experimental and theoretical investigation for salt water desalination using tubular direct contact membrane distillation is introduced. The effect of operating and geometric parameters on the unit performance was studied. These parameters include feed water inlet temperature, feed water flow rate, salt concentration, cooling water temperature and membrane inner diameter and length. System thermal efficiency and gain output ratio (GOR) are also evaluated. The investigated parameters were set as follows: 70 °C for inlet feed water temperature, 15–20 L/min for feed water flow rate, 0–40 g Nacl/L water for feed water salt concentration, 20–56 °C for the inlet cooling water temperature, and 15–20 L/min for cooling water flow rate. Maximum productivity, daily efficiency, and Gain output ratio (GOR) of the system reached 40.587 kg/day, 60.06% and 0.624 respectively. Finally, a good agreement has been found between the present numerical data and experimental results.