Microchannel Rapid Temperature Swing Adsorption of CO2 for Methane Production

A rapid thermal swing adsorption system combined with Sabatier reactor was developed to demonstrate the applicability of a NASA microchannel Mars In Situ Propellant Production (ISPP) system.  A thermal swing adsorption pump was designed to collect and compress CO₂ by rapidly temperature cycling eight cells filled with Molesieve 13X.  Recuperation of energy between cells was used to minimize heat and cooling requirements.  The collected CO₂ can be combined hydrogen from electrolyzed water to produce methane fuel using a microchannel Sabatier reactor. 

Tests were performed to compress CO₂ by 10 fold using a feed stream of 10% CO₂ and 90% N₂ at 1, 2, and 4 minute cycle times.  With the initial testing, a compression ratio of 5.3 was achieved with 71 to 79% thermal recuperation efficiency.  Subsequent modeling work has refined the design and the number of cells required to improve the overall system efficiency and simplify the process.  These results indicate similar thermal efficiencies can be achieved using a system with only four cells rather than eight.  Modeling results further demonstrate design changes required to obtain improved efficiencies and compression ratios.  Results of both the original experimental work and the more recent modeling efforts will be presented.