Professor John H. Lienhard
PI at MIT
Professor Greg Rutledge
PI at MIT
Professor Hassan A. Arafat
PI at Masdar Institute
This project is focused on the development of a membrane distillation (MD) desalination technology. MD is a method of thermal desalination whereby a hot, saline, feed stream is passed over a microporous hydrophobic membrane . The membrane is a thin polymer typically made of Teflon or polypropylene. The temperature difference between the two sides of the membrane leads to a vapor pressure difference that causes water to evaporate and pass through the pores. The water is held back by surface tension as the fluid forms a meniscus on the small pores. This pressure limits the pressure difference across the membranes and is primarily governed by the contact angle of the material and the pore size. MD systems can be run in a variety of configurations, which govern how fluid is collected from the permeate side. There is direct contact MD (DCMD), air gap MD (AGMD), sweeping gas MD (SGMD). SGMD is typically used for removing volatile vapors and is typically not used in desalination.
MD configurations (DCMD, AGMD, and VMD) have been analyzed from an energy efficiency standpoint and VMD was found to have fundamentally limited performance, due to the low condensing temperatures which limit how much heat can be recovered from the permeate vapor. AGMD and DCMD have the potential to produce low-cost water if properly optimized. Multi-stage, multi-pressure, cycles for VMD will be investigated for their energy efficiency to reduce the effect of low saturation temperature.
This research project has several key aspects of relevance to Masdar Institute's mission as well as Abu Dhabi, as it addresses sustainable energy (Solar and Wind) utilization and clean water supply. The project addresses a promising new technology for water desalination (membrane distillation). The research will also help in educating participating students to innovate in desalination system design and it will establish new capacity in the UAE.