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At least 253 records · Page 14

Regeneration of oxygen from carbon dioxide and water.

In a closed ecological system it is necessary to reclaim most of the oxygen required for breathing from respired carbon dioxide and the remainder from waste water. One of the advanced physicochemical systems being developed for generating oxygen in manned spacecraft is the solid electrolyte-electrolysis system. The solid electrolyte system consists of two basic units, an electrolyzer and a carbon monoxide disproportionator. The electrolyzer can reclaim oxygen from both carbon dioxide and water. Electrolyzer preparation and assembly are discussed together with questions of reactor design and electrolyzer performance data.

Weissbart, J.↗

An Assessment of the Ability of Potential Space-Borne Instruments to Resolve Spatial and Temporal Variability of Atmospheric Carbon Dioxide

Mounting concern regarding the possibility that increasing carbon dioxide concentrations will initiate climate change has stimulated interest in the feasibility of measuring CO2 mixing ratios from satellites. Currently, the most comprehensive set of atmospheric CO2 data is from the NOAA CMDL cooperative air sampling network, consisting of more than 40 sites where flasks of air are collected approximately weekly. Sporadic observations in the troposphere and stratosphere from airborne in situ and flask samplers are also available. Although the surface network is extensive, there is a dearth of data in the Southern Hemisphere and most of the stations were intentionally placed in remote areas, far from major sources. Sufficiently precise satellite observations with adequate spatial and temporal resolution would substantially increase our knowledge of the atmospheric CO2 distribution and would undoubtedly lead to improved understanding of the global carbon budget. We use a 3-D chemical transport model to investigate the ability of potential satellite instruments with a variety of orbits, horizontal resolution and vertical weighting functions to capture the variation in the modeled CO2 fields. The model is driven by analyzed winds from the Goddard Data Assimilation Office. Simulated CO2 fields are compared with existing surface and aircraft data, and the effects of the model convection scheme and representation of the planetary boundary layer are considered.

Andrews, Arlyn E.↗

An Assessment of the Ability of Potential Spaceborne Instruments to Resolve Spatial and Temporal Variability of Atmospheric Carbon Dioxide

Mounting concern regarding the possibility that increasing carbon dioxide concentrations will initiate climate change has stimulated interest in the feasibility of measuring CO2 mixing ratios from satellites. Currently, the most comprehensive set of atmospheric CO2 data is from the NOAA CMDL cooperative air sampling network, consisting of more than 40 sites where flasks of air are collected approximately weekly. Sporadic observations in the troposphere and stratosphere from airborne in situ and flask samplers are also available. Although the surface network is extensive, there is a dearth of data in the Southern Hemisphere and most of the stations were intentionally placed in remote areas, far from major sources. Sufficiently precise satellite observations with adequate spatial and temporal resolution would substantially increase our knowledge of the atmospheric CO2 distribution and would undoubtedly lead to improved understanding of the global carbon budget. We use a 3-D chemical transport model to investigate the ability of potential satellite instruments with a variety of orbits, horizontal resolution and vertical weighting functions to capture the variation in the modeled CO2 fields. The model is driven by analyzed winds from the Goddard Data Assimilation Office. Simulated CO2 fields are compared with existing surface and aircraft data, and the effects of the model convection scheme and representation of the planetary boundary layer are considered.

Andrews, Arlyn E.↗

Miniature carbon dioxide sensor

Sensor with no moving parts measures carbon dioxide partial pressures of 0 to 40 mm Hg for total pressures up to 14 psia with a full scale accuracy of 5 percent.

Mc Henry, T. F.↗

Transition Experiments on Blunt Bodies with Distributed Roughness in Hypersonic Free Flight in Carbon Dioxide

Blunt-body geometries were flown through carbon dioxide in the NASA Ames Hypervelocity Free Flight Aerodynamic Facility to investigate the influence of distributed surface roughness on transition to turbulence in CO2-dominated atmospheres, such as those of Mars and Venus. Tests were also performed in air for direct comparison with archival results. Models of hemispherical and spherically-blunted large-angle conical geometries were flown at speeds between 2.8 km/s and 5.1 km/s and freestream pressures between 50 Torr and 228 Torr. Transition fronts were determined from global surface heat flux distributions measured using thermal imaging techniques. Distributed surface roughness was produced by grit-blasting the model surfaces. Real-gas Navier-Stokes solutions were used to calculate non-dimensional correlating parameters at the measured transition onset locations. Transition-onset locations correlated well with a constant roughness Reynolds number based on the mean roughness element height. The critical roughness Reynolds number for transition onset determined for flight in CO2 was 223 +/- 25%. This mean value is lower than the critical value of 250 +/- 20% previously-established from tests conducted in air, but within the bounds of the expected measurement uncertainty.

ballistic ranges↗

Electrochemical carbon dioxide concentrator subsystem math model

A steady state computer simulation model has been developed to describe the performance of a total six man, self-contained electrochemical carbon dioxide concentrator subsystem built for the space station prototype. The math model combines expressions describing the performance of the electrochemical depolarized carbon dioxide concentrator cells and modules previously developed with expressions describing the performance of the other major CS-6 components. The model is capable of accurately predicting CS-6 performance over EDC operating ranges and the computer simulation results agree with experimental data obtained over the prediction range.

Marshall, R. D.↗