(628b) Development of a TSA Process for Metabolic CO2 Removal from Spacecraft Cabins Using a Structured 13X Adsorbent

NASA has a great deal of interest in the use of structured sorbents in environmental systems for space applications for a variety of reasons. The most important reason perhaps is to minimize or even eliminate the formation of sorbent dust. Sorbent dusting most recently caused the failure of a TSA unit on board the International Space Station (ISS). The use of a Catacel structured 13X adsorbent may alleviate the dusting problem associated with the TSA unit in the CDRA and possibly provide even better performance characteristics.

The Catacel structured 13X adsorbent is constructed of corrugated metal sheets rolled into a cylindrical shape in such a way that it forms parallel triangular channels with all three walls coated with zeolite crystals. One of the Catacel structured 13X adsorbents available for testing at USC contains 741 cells per square inch (CPSI)), has a 13X coating thickness of about 31 m, a bulk density of 171 kg/m³, and a low pressure drop of < 12 kPa/m at 20 m/s (a very high velocity). These properties make it ideal for use in high flow rate, low pressure drop applications where low attrition (i.e., minimal dusting) is a requirement. Moreover, since it is made of 50 m thick metal foil sheets, it should also have a very high thermal conductivity. This property may give rise to shorter cycle times in a TSA process, thus making the TSA beds much smaller than those in the current CDRA TSA unit.

The overall goal of this project is to design a temperature swing adsorption (TSA) process that utilizes a structured 13X adsorbent. This TSA cycle design would a drop-in replacement for the TSA unit on board the ISS. This design is based on simulations being carried out with the USC dynamic adsorption process simulator (DAPS) and validated experimentally using the USC single bed apparatus in a TSA mode. The latest results of this project will be presented.