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Space Station Freedom Carbon Dioxide Removal Flight Design
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Abstract
Boeing is responsible for Space Station Freedom (Work Package (WP) 01) which includes the Habitat and U.S. Laboratory modules, which includes the integration of the Environmental Control and Life Support System (ECLSS). Included as part of the ECLSS is the Atmosphere Revitalization (AR) subsystem. The AR subsystem provides for removal of metabolic carbon dioxide, removal of trace contaminants, and continuous monitoring of the cabin atmosphere major constituent composition during the Manned Tended Configuration (MTC) phase of station operations. The focus of this paper is on the Carbon Dioxide Removal Assembly (CDRA) flight design aspects of the Space Station Freedom (SSF) AR subsystem.
A Four Bed Molecular Sieve (4BMS) has been selected by Boeing as the CDRA for SSF. The CDRA removes carbon dioxide from an air slip stream pulled from the Cabin Air Temperature & Humidity Control (THC) assembly. The carbon dioxide is then desorbed to space vacuum using thermal/pressure swing methodology. Carbon dioxide will be removed at a rate equal to the time averaged carbon dioxide generation rate of the crew members.
The CDRA operates cyclically using me four beds to achieve a continuous removal process with simultaneous adsorption and regeneration of desiccant beds and carbon dioxide adsorbent beds. The 4BMS design is completely regenerative and has no scheduled maintenance requirements during the entire MTC phase of station operations.
To date 4BMS technology has been used in four generations of development testing. They are the NASA Core Module Integration System (CMIS), the Boeing Comparative Test, the Boeing Pre-development Operational Systems Test (POST), (1) and Subcontractor testing at AlliedSignal. The molecular sieve material has also successfully operated during the entire Skylab program removing carbon dioxide and humidity from the Skylab habitable atmosphere (2).
SSF is being designed for a crew of four astronauts with scarring in place for a closed loop AR, and to allow growth to the Eight Man Crew Capability (EMCC) configuration. The carbon dioxide removal function must remove experiment animal carbon dioxide at EMCC as well as crew metabolic carbon dioxide and store it for subsequent conversion in the closed loop AR carbon dioxide reduction system.
The MTC CDRA Normal mode of operation will remove 0.17 kg/hr of carbon dioxide (nominal 4-person generation rate) with an inlet carbon dioxide partial pressure of 3.0 mm Hg and a cabin pressure of 99.9-104.8 kPa. The CDRA has the ability to adjust the removal rate by +/-10% resulting in an effective range of 0.15 to 0.19 kg/hr.
The MTC CDRA Degraded mode of operation will remove 0.33 kg/hr of carbon dioxide (nominal 8-person generation rate) with an inlet carbon dioxide partial pressure of 6.0 mm Hg and a cabin pressure of 99.9-104.8 kPa. The Degraded mode also has the capacity to effective range of 0.30 - 0.36 kg/hr.
This paper will discuss the technology and operation of the MTC open loop CDRA, its functional interfaces within AR, ECLSS, and SSF, scars for growth to the closed loop CDRA operation, and specific performance attributes of the flight hardware design that is expected to be launched with the U.S. Laboratory A module on Mission Build (MB) flight six in 1996.
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Authors
Citation
Gentry, G. and Kay, R., "Space Station Freedom Carbon Dioxide Removal Flight Design," SAE Technical Paper 932108, 1993, https://doi.org/10.4271/932108.Also In
References
- Woodward L. Ka Robert “Space Station Freedom Pre-development Operational Systems Test Carbon Dioxide Removal Assembly,” Paper No. 901392 International Conference on Environmental Systems Williamsburg, Virginia July 1990
- Coull Tom “Skylab Regenerable Carbon Dioxide Removal System,” Paper No. 72-ENAv-4 Aviation & Space Division of The American Society of Mechanical Engineers San Francisco, CA May 1972
- Knox J. C. Gilley S. D. “Evaluation of the Carbon Dioxide Removal Assembly Requirements for the Space Station Freedom in the Manned Tended Capability through the Permanently Manned Capability Configurations,” Paper No. 921231 22nd International Conference on Environmental Systems Seattle, WA July 1992
- Russell Madison “Developing 4BMS Math Model for Space Station Freedom Carbon Dioxide Removal,” Paper No. 911470 International Conference on Environmental Systems San Francisco, CA July 1991
- von Jouanne Roger Barker Robert S. Sitler Glenn A. “Dew Point Analysis for Space Station Freedom,” Paper No. 921227 22nd International Conference on Environmental Systems Seattle, WA July 1992
- Hafale Bernard “Development of the Carbon Dioxide Removal System Blower Used on Space Station Freedom,” Paper No. 921188 International Conference on Environmental Systems Seattle, WA July 1992
- Matteau Dennis “Space Station Freedom Carbon Dioxide Removal Assembly Two-Stage Rotary Sliding Vane Pump,” Paper No. 921187 International Conference on Environmental Systems Seattle, WA July 1992
- Rowe Stephen, A. Morando Alexander, R. “Developing Real-Time Control Software for Space Station Freedom Carbon Dioxide Removal,” Paper No. 9164442 International Conference on Environmental Systems Seattle, WA July 1991