Residence time and carbon dioxide scrubbing efficiency in life support systems

Residence time affects the CO2 absorption rate and CO2 absorption capacity of different CO2 absorbents used in an enclosed space. For a given CO2 contents in the air stream at any given environmental condition, there is a corresponding residence time between CO2 and the absorbent which results in the maximum CO2 absorption efficiency. Different porosities for lithium hydroxide, Sodasorb, and Baralyme granules were studied. The residence time effects on the CO2 absorption patterns and CO2 absorption capacities were observed. Lithium hydroxide and the highest CO2 absorption capacity when the residence time was about 0.8 s. The CO2 absorption capacity of both Sodasorb and Baralyme was increased as residence time increased. However, when the residence time was less than 1.0 s, the CO2 absorption capacity of both absorbents was greatly reduced.