Development of a Unique, Passive, Microgravity Vortex Separator

Abstract

In the microgravity environment experienced by space vehicles, liquid and gas do not naturally separate as on Earth. This behavior presents a problem for two-phase space systems, such as environment conditioning, waste water processing, and power systems. Furthermore, with recent renewed interest in space nuclear power systems, a microgravity Rankine cycle is attractive for thermal to electric energy conversion and would require a phase separation device. Responding to this need, researchers have conceived various methods of producing phase separation in low gravity environments. These separator types have included wicking, elbow, hydrophobic/hydrophilic, vortex, rotary fan separators, and combinations thereof. Each class of separator achieved acceptable performance for particular applications and most performed in some capacity for the space program. However, increased integration of multiphase systems requires a separator design adaptable to a variety of system operating conditions. To this end, researchers at Texas A&M University (TAMU) have developed a Microgravity Vortex Separator (MVS) capable of handling both a wide range of inlet conditions as well as changes in these conditions with a single, passive design. Currently, rotary separators are recognized as the most versatile microgravity separation technology. However, compared with passive designs, rotary separators suffer from higher power consumption, more complicated mechanical design, and higher maintenance requirements than passive separators. Furthermore, research completed over the past decade has shown the MVS more resistant to inlet flow variations and versatile in application. Most investigations were conducted as part of system integration experiments including, among others, propellant transfer, waste water processing, and fuel cell systems. Testing involved determination of hydrodynamic conditions relating to vortex stability, inlet quality effects, accumulation volume potential, and dynamic volume monitoring. In most cases, a 1.2 liter separator was found to accommodate system flow conditions. This size produced reliable phase separation for liquid flow rates from 1.8 to 9.8 liters per minute, for gas flow rates of 0.5 to 180 standard liters per minute, over the full range of quality, and with fluid inventory changes up to 0.35 liters. Moreover, an acoustic sensor, integrated into the wall of the separation chamber, allows liquid film thickness monitoring with an accuracy of 0.1 inches. Currently, application of the MVS is being extended to cabin air dehumidification and a Rankine power cycle system. Both of these projects will allow further development of the TAMU separator.

A novel arterial Wick for gas–liquid phase separation

“…These systems can be classified by the types of forces they use to facilitate the separation process into capillary and membrane separators, active and passive centrifugal, and separators that use alternative forces such as electric, magnetic, and acoustic forces . In general, passive separators that have no moving mechanical parts are preferred to active separators due to their zero power consumption and less overall weight, volume, and complexity, and they have been investigated intensively . For instance, Jenson et al employed the wedge conduit geometry as a passive bubble phase separating device that can remove single bubbles with a diameter larger than 7.2 mm.…”

Development of a passive phase separator for space and earth applications

“…To meet this demand, various methods to produce phase separation in low gravitational environment have been developed. These have included wicking, using membranes and hydrophobic/hydrophilic meshes, designing the flow to contain sudden direction changes or elbows, or a combination of the above [1][2][3][4][5][6][7][8][9][10][11]. For instance, recent publications have discussed the effects of the gravity level on using flow pattern modulation to passively enhance the separation using suspended mesh cylinders [2][3][4].…”

Development of an Efficient Phase Separator for Space and Ground Applications

“…In the second, the tank is fixed, and the rotation is induced by eccentric injection of the mixture (Free Vortex Separator or FVS). These passive separators have no moving mechanical parts, require low power, and have been investigated intensively owing to their simplicity and dependability [1][2][3]. McQuillen et al at NASA Glenn Research center have been developing the Cascade Cyclonic Separation Device (CSD-C) since the mid 90's [4,5].…”