Air gap membrane distillation: Desalination, modeling and optimization

Abstract

Response surface methodology has been applied for modeling and optimization of air gap membrane distillation process used in desalination. Regression models have been developed to predict the performance index and the specific performance index that takes into consideration the energy consumption as function of different variables. The developed models have been statistically validated by analysis of variance. The rejection factors were found to be greater than 99.9%. Two optimal operating conditions have been determined for each response. For the performance index the optimal solution was a cooling inlet temperature of 13.9 degrees C, a feed inlet temperature of 71 degrees C and a feed flow rate of 183 L/h. Under these conditions the experimental performance index, 47.189 kg/m(2).h, was found to be the greatest value among all performed experiments. For the specific performance index, the optimal solution was also 13.9 degrees C cooling inlet temperature, 59 degrees C feed inlet temperature and 205 L/h feed flow rate. When applying these last optimum conditions, the obtained experimental specific performance index, 188.7 kg/kWh, was also found to be the highest value. This corresponds to a specific energy consumption of 5.3 kWh/m(3). In all cases, the experimental results are in good agreement with the predicted ones by the developed models.