Optimization of module length for continuous direct contact membrane distillation process

Module length plays an important role in dictating the overall performance of membrane distillation (MD) process. In current study, the performance behavior of a small scale module applied for direct contact membrane distillation (DCMD), has been simulated and extrapolated to obtain temperature and flux profiles along the modules with lengths varying from 10 to 2000 cm. The profiles obtained under various conditions have been used to calculate the key performance parameters of a plant treating seawater at feed capacity of 1000 m3/h. The operational mode of the plant comprises of multiple stages connected in series to achieve a desired recovery factor. The effect of module length on key performance parameters including specific energy consumption, membrane area and number of stages has been analyzed. To calculate the optimum module length, the performance parameters have been translated into operational and fixed capital costs by performing a detailed cost analysis based on existing pilot MD units installed under the framework of European project MEDIRAS. Dependence of optimum module length on operating conditions, membrane thickness and overall recovery factor has been analyzed.