Membrane distillation (MD) is a thermally driven distillation process. In this process, hot feed stream is passed along one side of a hydrophobic membrane, which is only permeable for water vapor and retains liquid water, whereas the other side is kept at a lower (cooler) temperature. Due to temperature difference across the membrane, water evaporates at the feed-membrane interface and the induced partial vapor pressure difference drives only water vapor through the membrane where it condenses on the other side of the membrane, called the permeate side.

MD requires low-grade heat, which can be harvested from solar thermal energy, and other renewable or waste heat sources. Also, unlike the well-known reverse osmosis, MD operates at a lower water pressure, which in turns reduces the capital and operational costs. All these advantages make MD ideal for remote area desalination plants installations with minimal infrastructure and less demanding membrane characteristics.  However, MD is faced with challenges that are yet to be addressed in order for this technology to be competitive with conventional desalination techniques. In recent years, MD has been coupled with renewable energy sources, such as solar thermal collectors and photovoltaics (PV) panels, to capitalize on the attractive features of MD. However, the unsteady nature of renewable energy sources imposes a challenge on solar powered membrane distillation (SPMD) that requires special attention on process modeling and system control. Moreover, over time, membrane permeability changes due to scaling and fouling.  All these factors have to be taken into consideration when modeling MD.

The objective of this project is to

1. develop  dynamical model describing the membrane distillation process,
2.  characterize the membrane for an optimal utilization of the system
3.  design optimal control strategy to control the productivity of the system taking into account the economical aspect. 
   

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