Scientific and Technical Aerospace Reports Volume 39 April 6, 2001

20010024956 NASA Ames Research Center, Moffett Field, CA USA
Separation of Carbon Monoxide and Carbon Dioxide for Mars ISRU-Concepts
LeVan, M. Douglas, Vanderbilt Univ., USA; Finn, John E., NASA Ames Research Center, USA; Sridhar, K. R., Arizona Univ.,
USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp.
1204-1216; In English; See also 20010024890; No Copyright; Avail: CASI; A03, Hardcopy; A10, Microfiche
Solid oxide electrolyzers, such as electrolysis cells utilizing yttria-stabilized zirconia, can produce oxygen from Mars atmospheric
carbon dioxide and reject carbon monoxide and unreacted carbon dioxide in a separate stream. The oxygen-production
process has been shown to be far more efficient if the high-pressure, unreacted carbon dioxide can be separated and recycled back
into the feed stream. Additionally, the mass of the adsorption compressor can be reduced. Also, the carbon monoxide by-product
is a valuable fuel for space exploration and habitation, with applications from fuel cells to production of hydrocarbons and plastics.
In our research, we will design, construct, and test an innovative, robust, low mass, low power separation device that can recover
carbon dioxide and carbon monoxide for Mars ISRU. Such fundamental process technology, involving gas-solid phase separation
in a reduced gravitational environment, will help to enable Human Exploration and Development of Space. The separation device
will be scaled to operate with a CO2 sorption compressor and a zirconia electrolysis device built at the NASA Ames Research
Center and the University of Arizona, respectively. In our research, we will design, construct, and test an innovative, robust, low
mass, low power separation device that can recover carbon dioxide and carbon monoxide for Mars ISRU, Such fundamental process
technology, involving gas-solid phase separation in a reduced gravitational environment, will help to enable Human Exploration
and Development of Space. The separation device will be scaled to operate with a CO2 sorption compressor and a zirconia
electrolysis device built at the NASA Ames Research Center and the University of Arizona, The separation device will be scaled
to operate with a CO2 sorption compressor and a zirconia electrolysis device built at the NASA Ames Research Center and the
University of Arizona, Research needs for the design shown are as follows: (1) The best adsorbent for the process must be determined.
(2) Adsorption isotherms must be measured, both for pure components and mixtures. (3) Mathematical modeling must
be performed to provide a solid framework for design. (4) The separation system must be constructed and tested. (5) System
integration must be studied.
Author (revised)
Mars Atmosphere; Carbon Dioxide; Carbon Monoxide; Electrolysis; Oxygen Production
20010024957 Iowa Univ., Iowa Inst. of Hydraulic Research, Iowa City, IA USA
Rivulet Dynamics with Variable Gravity and Wind Shear
Marshall, J. S., Iowa Univ., USA; Ettema, R., Iowa Univ., USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport
Phenomena Conference; December 2000, pp. 1217-1227; In English; See also 20010024890; No Copyright; Avail: CASI; A02,
Hardcopy; A10, Microfiche
This study investigates rivulet dynamics under conditions of variable gravity and wind shear. Particular attention is focused
on the dynamics of systems comprising a large number of interacting rivulets, which typically form following breakup of a liquid
sheet. Rivulets form when the upper free surface of a liquid sheet flowing over a rigid plate deflects downward and connects to
the plate. The flow within the liquid layer may be driven by forces such as wind shear or gravity. The onset of rivulet formation
may be triggered by a variety of effects, such as surface roughness of the solid plate, turbulence in the air stream, or thermocapillary
instability of the liquid-gas interface. At the head of the rivulet, the liquid-gas-solid contact line forms a U-shaped pattern on the
plate. Downstream of the formation point, rivulets exhibit a variety of instabilities, including lateral meandering and vertical instabilities
that lead to beading and drop fall-off from the rivulet tip. Rivulets play an important role in a wide variety of applications
in the energy, chemical and aerospace industries. Rivulet formation on the wings of an airplane flying in rain decrease the aerodynamic
efficiency and (under freezing conditions) control the pattern of ice formation on the wings. Rivulet formation enhances
heat transfer rate to the liquid stream due to the large ratio of liquid surface area to cross-sectional area. This fact has been used
in a variety of cooling systems, including cooling streams of solar panels, tubes of mist-cooled heat condensers, and liquid-metal
blanket cooling of fusion reactors. Mass transfer rates to rivulets is important for applications such as trickle-phase chemical reactors,
flow over a catalytic pellet bed, and flow within columns with structured packing. Rivulet formation in two-phase liquid-gas
flow in a tube controls the transition between annular flow to droplet flow. Rivulet formation is an undesirable feature in several
coating processes that limits the minimum thickness of the coating sheet and results in inefficient and non-uniform coating of the
substrate. The project will utilize microgravity conditions to investigate rivulet dynamics with variable gravity and wind shear.
The planned experiments will be conducted using a centrifugal ”Couette flume”, consisting of inner and outer cylinders and a
liquid water layer of a prescribed thickness coating the inner surface of the outer cylinder. Rotation of the outer cylinder produces
different effective gravitational conditions due to the radial centrifugal force. Differential rotation of the inner cylinder is used
to generate a prescribed wind shear. Data on rivulet formation and geometry will be obtained using two different laser-induced
fluorescent imaging methods. The experiments will be conducted through the NASA Parabolic Flight Program. A computational
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