Performance analysis of a thermal-driven tubular direct contact membrane distillation system. (August 2019) - Shafieian, Abdellah
Highlights: An accurate and cost-effective multi-step model has been proposed for DCMD systems. Flows should be kept near the end or beyond the transition range for higher productivity. Heating up the feed stream is more efficient than cooling the permeate stream down. The performance of the tubular DCMD system is independent of the feed water salinity. Abstract: This paper examines the performance of a thermal-driven tubular direct contact membrane distillation (DCMD) system theoretically and experimentally. A multi-step mathematical model was developed to predict the freshwater productivity of the tubular DCMD module applicable for both small and large-scale applications by considering the changes in the operational variables along the membrane's length. The proposed model was verified by building an experimental rig which was tested under different operational conditions. The results showed that keeping the mass flow rates in the hot and cold channels either near the end or beyond the transition range of the flows results in higher water production. In addition, heating up the feed stream is more efficient for enhancing water productivity than using the same amount of energy to cool the permeate stream down. Finally, the effects of operational and physical factors on the freshwater productivity were identified and discussed.