Measurement of Trace Water Vapor in a Carbon Dioxide Removal Assembly Product Stream

摘要

The International Space Station Carbon Dioxide Removal Assembly (CDRA) uses regenerable adsorption technology to remove carbon dioxide (CO_2) from cabin air.CO_2 product water vapor measurements from a CDRA test bed unit at the NASA Marshall Space Flight Center were made using a tunable infrared diode laser differential absorption spectrometer (TILDAS) provided by NASA Glenn Research Center.The TILDAS instrument exceeded all the test specifications,including sensitivity,dynamic range,time response,and unattended operation.During the CO_2 desorption phase,water vapor concentrations as low as 5 ppmv were observed near the peak of CO_2 evolution,rising to levels of ~40 ppmv at the end of a cycle.Periods of high water concentration (>100 ppmv) were detected and shown to be caused by an experimental artifact.