Browsing by Author "Okada, Osamu"
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Item CO2 Control in Space Station and Space Suit by Novel Facilitated Transport Membranes(46th International Conference on Environmental Systems, 2016-07-10) Okada, Osamu; Teramoto, Msaaki; Hanai, Nobuaki; Miyata, Jyunya; Kiyohara, Yasato; Sakurai, MasatoFor the CO2 control in the space station, membrane separation is attractive as it is a simple continuous system with low energy consumption and no capacity limit as CO2 uptake at the feed side of the membrane and release at the permeate side occur simultaneously. In order to apply membranes for space use, development of membranes with extremely high CO2 selectivity over O2 and N2 is required for minimizing the O2 and N2 losses. In our previous paper (ICES - 2014), we reported novel CO2 selective facilitated transport membranes. These are gel-type membranes supported on microporous membranes. The CO2 permeance and CO2/N2 selectivity measured by the sweep gas method were favorably compared to those reported so far. In the present study, a 0.75% CO2/99.3% O2 mixture was mainly used as a feed gas, and the membrane performance was evaluated by the vacuum mode method where the permeate side PS was kept at low pressures at room temperature without sweep gas. We found that PS was very important factor, which influences the membrane performance. As PS increased, both CO2 and O2 permeances increased with CO2/O2 selectivity higher than 4000. The CO2 permeance was 1.2E4 Ncm3/(cm2 s cmHg) at 75% of relative humidity. The CO2/N2 selectivity was about twice the CO2/O2 selectivity. As the CO2 partial pressure decreased, CO2 permeance increased. The performance of the membrane module, in which the developed membranes are supposed to be incorporated, was simulated. When the module is applied to space station, the estimated membrane area was about 43 m2 at the CO2 removal rate (CRR) of 1 kg/day. In the case of space suit, the area was about 46 m2 at CRR=93g/h. The CO2 concentration recovered from the permeate side of the membrane is higher than 95% suggesting very small O2 and N2 losses.Item Novel CO2 Selective Membranes for CO2 Control in Space Station and Space Suit(44th International Conference on Environmental Systems, 2014-07-13) Okada, Osamu; Teramoto, Masaaki; Nonouchi, Tamotsu; Hanai, Nobuaki; Miyata, Junya; Kiyohara, Yasato; Sakurai, MasatoFor the CO2 control in the space station, attention has been mainly paid to the adsorption method. One of the alternatives to this method is the separation using membranes, which is a simple continuous system with low energy consumption and no capacity limit since CO2 absorption at the feed side of the membrane and desorption at the permeate side occur simultaneously. In order to apply membranes for the CO2 removal in space stations and also in space suits, development of membranes with extremely high CO2 selectivity over O2 and N2 is required for minimizing the O2 and N2 losses. In the present work, we developed several types of CO2 selective facilitated transport membranes. These are gel-type membranes supported on microporous membranes. The gel layer contains a CO2 carrier, which enhances CO2 permeability, and also an additive, which improves the permeation characteristics. Typical membrane performances observed at low CO2 partial pressures (0.7kPa) and room temperature are as follows. CO2 permeance: 1.23104 1.71104 Ncm3 cm-2 s-1 cmHg-1 (4.1105 5.7105 mol m-2 s-1 kPa-1), CO2/N2 selectivity: 570013700, which is much larger than those reported so far. CO2/O2 selectivity was about half the CO2/N2 selectivity. The performance of membrane module, in which the developed membranes are supposed to be used, was estimated when the module is applied to space stations and space suits. It was found that the mol fraction of CO2 recovered from the permeate side of the membrane is higher than 0.96 (dry basis), which suggests very small O2 and N2 losses. When this membrane is applied to a space suit, the membrane area and volume of the membrane module required for removing CO2 at the rate 2.23 kg/day were approximately estimated as 31.6 m2 and 16 L, respectively. The membrane module works also for removing water vapor from space suits.