Two Phase Fluid Management for Hydroponics

Hydroponics is the cultivation of plants in water containing dissolved inorganic nutrients. Over the past two decades, hydroponics has established itself as a valued component in the overall effort to achieve closed cycle environmental systems. This has a particularly significant impact on future long-duration missions such as lunar colony and exploration of the solar system where resupply is either impossible or impractical.

In order to make hydroponics a truly practical solution in the microgravity conditions found in space, it is essential that techniques be developed for separating liquid from air in a simple and effective manner. The liquid gas separator proposed is an improvement on existing LGS designs because it simply and effectively meets the four basic requirements for liquid gas separation in space flight hydroponics systems: (1) the ability to handle liquids in terms of tens of liters per day, (2) extremely low power consumption, (3) high reliability with constant use over long duration, and (4) nominal 100 percent efficiency in the removal of air from water. The separation of water from air is much less critical since it is assumed that a hydroponic unit would operate at very high humidity (60-80%) and small amounts of liquid water could occasionally be accommodated.* However; air bubbles in the water supply system could lead to catastrophic failure of the system.

This paper will primarily concentrate on the separation of air from the liquid water stream and will present several concepts which will advance the practical application of hydroponics in a microgravity environment.