Microgravity Phase Separation in a Fixed Cylinder

Texas A&M University

Phase separation under the influence of earth's gravity is a simple process. Low density gases naturally float to the surface of liquids as a result of gravity driven buoyancy forces. Unfortunately, the effects of gravity are negligible in space and natural phase separation is lost. Current methods of microgravity phase separation employ devices which create centripetally driven buoyancy forces to form a gaseous core surrounded by liquid, but require a great deal of power to operate and are often unreliable.

The proposed phase separator uses the intrinsic momentum of a two-phase flow to form a vortex in a fixed right cylinder. A gaseous core forms in the center of the cylinder as a result of centripetally driven buoyancy forces with low energy input. This method of microgravity separation was shown to be viable by the Texas A&M team in the 1997 Reduced Gravity Student Flight Opportunities Program, but this year's design is improved by reducing volume and surface area in order to minimize friction forces. Improved data acquisition mechanisms are also used to aid analysis and enable the design to be adapted and scaled to meet the requirements of many applications.

Improved phase separator technology will enable increased usage and control of two phase systems in future space missions. In space nuclear reactors, bubbles in liquid lithium coolant due to gaseous fission products and helium can adversely affect pumps and require a phase separator for removal. A phase separator is also required to operate bioreactor water purification systems in microgravity. In general, two phase flow increases efficiency in heating, cooling, and power systems.

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Last Modified: Tue May 19 1998
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