Development of the Liquid Amines Ground-Based Test System

Removing carbon dioxide from breathable air is of vital safety and importance to future crewed missions. NASA Ames Research Center (ARC) is specifically investigating how to do this more efficiently using a liquid sorbent. One approach utilizes liquid amines as a liquid sorbent manipulated and contained via capillary flow. A test stand originally designed at NASA Johnson Space Center (JSC) is currently being used for testing which allows for air plug flow across a liquid sorbent contactor assembly. The current contactor configuration is set up with vertically oriented capillary flow wedges, but carbon dioxide (CO2) capture rates were found to be significantly lower than expected. Due to gravity, the liquid flow through the vertical wedges results in very low Diglycolamine Agent (DGA) retention time in the contactor assembly giving the DGA mixture insufficient time to absorb CO2. Furthermore, the current wedge orientation unfortunately does not allow for testing of different flow regimes because gravity-assist is currently the main limiting flow driver. Alternatively, it can be hypothesized that using a horizontal wedge configuration will allow for increased liquid retention time and testing of different flow regimes in the liquid sorbent contactor. Preliminary 3D modeling and air flow simulations are being created for a horizontally oriented wedge contactor. Since the original NASA JSC test stand allows for removal and replacement of the vertical contactor assembly, the new horizontal wedge configuration contactor is being designed to connect to the existing structure. With the new contactor design, it would then be possible to experimentally investigate the CO2 absorption relationship on liquid flow rate and other various liquid sorbent properties.