Continued Development of the Brine Evaporation Bag
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The Brine Evaporation Bag (BEB) is a membrane based bag system for the dewatering of brine. Previous studies showed the ability of the BEB to dewater brine at low temperatures with a 96% mass reduction. Additionally, a microgravity flight showed the BEB is microgravity compatible. Current work focuses on the effects of temperature, vacuum, purge gas flow rate, membrane area, and membrane permeability on the rate of dewatering within a vacuum oven configured to mimic the Heat Melt Compactor. Within this study, it was found that changing the temperature or level of vacuum would change the rate of dewatering. The purge gas, membrane area, and membrane permeability did not affect the dewater rate. The reason for this behavior may be that the dewatering is heat transfer limited, and out of all the parameters studied, only the temperature and vacuum have an effect on the heat transfer rate. The ISS produces brine at a rate of 1.2 L/day. This initial study showed that it is possible to remove water from a BEB at a rate of 1.6 L/day in this breadboard configuration; even at moderate temperatures. Development of a dedicated BEB Evaporator will be discussed. In addition, it is further postulated that a specifically designed BEB Evaporator would result in an increased dewatering rate allowing for even lower operating temperatures or faster dewatering rates.