Abstract
Membrane distillation (MD) is a newly emerging technology that receives growing attention in the water desalination and purification industries. A mathematical model for MD unit is validated using experimental data. The mass and energy balances were simultaneously calibrated against the collected distillate production rate and measured temperature of the reject permeate stream. The validated model is utilized to evaluate the performance of the process using energy and exergy analysis. This analysis tool will help in process design and operating condition selection that saves energy and improve performance. It is revealed that the exiting warm permeate is responsible for great amount of exergy losses if disposed to the environment. Repeated recycling the outlet permeate to successive MD units arranged in parallel improves the thermal energy effectiveness and increases the production rate. In fact, recovery ratio is increased from 6 to 25% and the exergy lost from the system with exiting permeate is reduced from 1.2 kW to almost null.