AbstractThis study evaluates the recovery of pure water by vacuum membrane distillation (VMD). The VMD process has been experimentally studied using a polytetrafluroethylene (PTFE) membrane for aqueous sodium chloride solution containing salt concentration of 20,000 ppm and permeate pressure of 7 kPa. The percentage recovery was observed to increase with time of operation and in 183 h, it became 86%. A mathematical model for recovery has also been developed and validated with experimental data. Heat transfer and mass transfer correlations have been developed for the range of feed flow rate of 0.5–2 lpm and feed bulk temperature of 40–60°C. The effect of feed salt concentration and membrane fouling was also studied on permeate flux. Permeate flux was found to decrease by 15 and 10% at 55 and 60°C, respectively, on increasing feed salt concentration from 5 to 40 g/l. The permeate flux was observed to decrease by 8% from 26.1 to 24 kg/m2 h after continuous operation of 180 h at 60°C and 20,000 ppm feed salt ...