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International Space Station Carbon Dioxide Removal Assembly Testing
| Content Provider | Semantic Scholar |
|---|---|
| Author | Knox, James C. |
| Copyright Year | 2000 |
| Abstract | Performance testing of the International Space Station Carbon Dioxide Removal Assembly flight hardware in the United States Laboratory during 1999 is described. The CDRA exceeded carbon dioxide performance specifications and operated flawlessly. Data from this test is presented. INTRODUCTION This paper reports the Carbon Dioxide Removal Assembly (CDRA) and Atmosphere Revitalization System (ARS) testing performed at Kennedy Space Center in support of the International Space Station program. The specific test discussed is the Closed Hatch Environmental Control and Life Support System (ECLSS) Qualification test. The test article is the US Laboratory (USL), to be launched on assembly flight 5A Closed Hatch ECLSS (CHE) Qualification testing was conducted in April and May of 1999. The CDRA is described first, as the primary subject of this paper. The overall Atmosphere Revitalization Subsystem will be described with respect to functionality, connectivity, and interfaces with other subsystems. The test configuration of the US Lab as it relates to the ARS operation will be described. Support equipment used during the CHE Qualification Test will be identified. The test objectives and operational steps will be outlined. Finally, test data pertaining to ARS operations will be presented and conclusions drawn. CDRA DESCRIPTION As show in Figure 1, the CDRA is tightly integrated and mounted on slides for installation in the Atmosphere Revitalization System rack. Air selector valves are visibly numbered 101 through 106. The blower and precooler orbital replacement unit (ORU) is visible in the right center section of the drawing. Process air and coolant water interfaces are on the lower right of the drawing. The sorbent beds are not clearly visible, but are behind the valves and tubing. Controllers for the bed heaters, air-save pump, and blower are on the left side, identified by the many electrical connectors. The air-save pump resides below the controllers. The operation of the CDRA can be explained with the aid of the schematic shown in Figure 2. The CDRA continuously removes carbon dioxide (CO2) from the ISS atmosphere. The four beds consist of two desiccant beds and two CO2 sorbent beds. The system operates such that one desiccant bed and one CO2 sorbent bed are adsorbing while the other two beds are desorbing. When a new half cycle begins, the beds switch sorbent modes. The incoming air stream to the CDRA is downstream of a condensing heat exchanger, and has a dewpoint and drybulb temperature of 4.4 to 10°C (40 to 50 °F) _. The air stream passes first through a desiccant bed to remove much of the moisture from the process air. The temperature of the air stream rises as it flows through the desiccant bed due to the heat of adsorption. The process air is then drawn through the system blower and then through an air-liquid heat exchanger or precooler. The precooler increases CO2 sorbent efficiency by reducing process air temperature before entering the CO2 sorbent bed. Prior to returning to the cabin, the air stream passes through the desiccant bed that adsorbed moisture from the previous half cycle. The wet desiccant bed desorbs this moisture to the air stream and returns it to the cabin atmosphere. This is calted a water-save system, in contrast to the 2-bed Skylab system, which vented adsorbed water to space. The alternate CO2 sorbent bed desorbs by heating with integral electrical heaters and application of space vacuum or, for ground testing, a simulated space vacuum. The heat supplied by the electrical heaters serve two purposes; it breaks the bond the CO2 has with the sorbent material, and in the subsequent half-cycle heats the passing air-stream to dry out the desorbing desiccant bed. For the first 15 minutes of each half-cycle, the air-save pump operates to remove residual air from the desorbing sorbent bed and returns it to the cabin. |
| File Format | PDF HTM / HTML |
| DOI | 10.4271/2000-01-2345 |
| Alternate Webpage(s) | https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000072884.pdf |
| Alternate Webpage(s) | https://doi.org/10.4271/2000-01-2345 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
