Abstract
We developed a CO2 removal device as a part of life-sustaining devices in ISS. We measured CO2 discharge rate and CO2 concentration in discharge gas from adsorption/desorption beds including zeolite 5A with aspect ratios (bed length L/ diameter D) of 0.5, 3.9 and 8.5. The discharge rate had two peaks caused by flow of remained air among zeolite pellets and desorption of CO2 from the zeolite during heating and evacuation. The CO2 concentration in the discharge gas was independent from the aspect ratio. The upper limit of bed length Li was found to be 0.32m to avoid the effect of the pressure gradient in the longitudinal direction, which reduces the obtained CO2 recovery efficiency. The adsorption band length Za and its moving velocity VZa increased from 0.20 to 1.31 m and from 2.1 x 10-3 to 1.4 x 10-2 m/min with decreasing bed diameter, respectively. The optimum bed length L is between taVZa (ta: adsorption time) and Li to obtain the highest CO2 recovery efficiency. The optimum combination of D and L is 0.3 and 0.32m, respectively, for minimization of diameter.
