Study of advancement to higher temperature membrane distillation

It is well known that the mass flux (J) and the membrane thermal efficiency (η) of membrane distillation increase with the feed flow temperature. A comprehensive laminar and turbulent flow model for simulating and evaluating the performance of direct contact membrane distillation (DCMD) when operated at inlet feed temperature (Tf,i) from 80 °C to 180 °C, higher than the customary maximum of ~80 °C, was developed and used to explain and assess the performance of such high temperature DCMD, as well as the potential associated problems of the needed higher operating pressure, and provide knowledge useful for their future design and optimization. Some of the key results are that raising Tf,i from 80 °C to 180 °C, increases J 9.4-fold, and η 2.1-fold, and decreases the specific energy consumption (SEC) 2.9-fold. Raising the flow Reynolds number from 1200 to 7000 increases J 2.6-fold and η by 15%, but SEC increases 2.3-fold. The needed system pressurization does not affect the process performance significantly. The higher operating temperatures also provide more practical opportunities for heat recovery, which could significantly further raise overall system efficiency.