Search Results

A generalized computer program for analysis of pressure and composition in multiple volume systems has been under development by the National Aeronautics and Space Administration (NASA) since 1976. This paper describes the most recent developments in the program. These improvements include the expansion of the program to nine volumes, improvements to the model of the International Space Station (ISS) carbon dioxide removal system, and addition of a detailed Sabatier carbon dioxide reduction mode. An evaluation of the feasibility of adding of trace contaminant tracking was also performed. This paper will also present the results of an analysis that compares model predictions with ISS flight data for carbon dioxide (CO2) maintenance.

A closed-loop air revitalization system requires continuous removal of CO2 from the breathing air and an oxygen recovery system to recover oxygen from the waste CO2. Production of oxygen from CO2 is typically achieved by reacting CO2 with hydrogen in a reduction unit such as a Sabatier reactor. The air revitalization system of International Space Station (ISS) currently operates on an open loop mode where CO2 is being vented into the space vacuum due to lack of a Sabatier Reactor. A compressor and a storage device are required to interface the Carbon Dioxide Removal Assembly (CDRA) and the Sabatier reactor. This compressor must acquire the low-pressure CO2 from CDRA and provide it at a high enough pressure to the Sabatier reactor. The compressor should ensure independent operations of CDRA and Sabatier reactor at all times, even when their operating schedules are not synchronized.

A SINDA/FLUINT model was developed for performing the thermal analysis of the compressible gaseous nitrogen (GN2) flow of X-38 pressure control system (PCS). The purpose of this analysis is to predict the thermal performance of X-38 PCS for the first mission phase, and to ensure that the GN2 pressure in tank stays above 1000 psi and the GN2 temperature in tank stays above −65°F during a real mission phase. The model simulations of the X-38 PCS have been conducted with the flowrates of the first mission phase for different ambient and GN2 temperatures with/without heating the GN2 tank wall. The predicted results show that the GN2 pressures and temperatures fulfill the requirements and limitations of the X-38 pressure control system without heating the GN2 tank wall. The electrical heaters on the GN2 tank exterior may be eliminated.