2:15 PM - 2:30 PM
[AOS14-03] Physico-chemical Life Support System for Manned Space Exploration
★Invited Papers
Keywords:ECLSS, Air re-vitalization, Water re-vitalization, Oxygen Circulation
Spacecraft air
The International Space Station (ISS) flies at an altitude of 400 km. About six astronauts are staying there. The interior of the ISS is kept at 1 atmospheric pressure, the same as on the ground, and the environment control and life support system ECLSS (Environmental Control Life Support System) maintains the temperature and humidity by purifying the air and water you need to bring with you. Is required. Human lungs are designed to breathe air with an oxygen partial pressure of 0.2 atm. The space station is filled with the same ratio of nitrogen and oxygen as on Earth. Nitrogen and oxygen for the station will come from the ground.
NASA's water electrolysis equipment (OGA: Oxygen Generation Assembly) generates oxygen through water electrolysis, and since hydrogen is dangerous, it is exhausted into space. It consumes oxygen and expels carbon dioxide into the cabin, increasing the carbon dioxide concentration. The concentration of carbon dioxide on Earth is about 350ppm-400ppm, but inside the ISS it is more than 4000ppm, about 10 times higher than on the ground. On the Space Shuttle, LiOH was the main device for carbon dioxide removal, but on the ISS, it is used as a backup in an emergency.
2LiOH+CO2 -> Li2CO3+H2O (1)
LiOH canisters need to be replaced frequently, and regenerative air purifiers are required for long missions. CDRA (Carbon Dioxide Removal Assembly) is a carbon dioxide removal device in the United States. After passing through a filter, the air is dehumidified in an adsorption column containing silica gel and then passed through a zeolite adsorption column. Carbon dioxide is adsorbed by the zeolites, while oxygen and nitrogen pass through. When the zeolite adsorption column is saturated with carbon dioxide, the saturated adsorbent is heated to desorb the absorbed carbon dioxide and discharge it overboard. Since the CDRA has two adsorption units for carbon dioxide, continuous operation is possible because one adsorption unit can adsorb carbon dioxide during the regeneration process in which the other unit is heated to release carbon dioxide. In the initial operation of the ISS, oxygen was generated by water electrolysis, and hydrogen was exhausted into space. On the other hand, the carbon dioxide in the cabin is also separated and concentrated and thrown into space. Couldn't we get something useful out of this discarded water and carbon dioxide? The idea to solve it is the idea of generating water by the Sabatier reaction. NASA has a Sabatier reactor to reduce the CO2 emitted by the three to produce water. Oxygen is produced by electrolyzing the water. The chemical formula of the Sabatier reaction is as shown in formula (2), and the oxygen contained in carbon dioxide is the oxygen contained in water.
CO2 + 4H2 -> CH4 + 2H2O (2)
Plants absorb carbon dioxide and produce oxygen on the ground, but on spacecraft, the air is regenerated using physicochemical methods.
water in a spaceship
The average American consumes 605 liters of water per day. Space station crews live on about 3.5 liters of water a day.
The urine processor UPA (Urine Processor Assembly) is mainly mounted on WRS rack 2 and recycles urine into drinking water. The principle of urine processing is to heat water containing urine with a heater to generate steam. The most important part of this process is the Distillation Assembly (DA). The boiling point is lowered by reducing the pressure inside to 0.048 atm. Urine is rotated at 220 rpm in a cylindrical heater, centrifugal force pushes the liquid inside the cylinder, and vapor is collected from the center and taken out as distilled water. Non-volatile impurities do not evaporate, so 97% can be removed, but ammonia and alcohol volatilize. Volatile components are oxidized by an oxidation catalyst, treated with an ion exchange resin to produce pure water, and iodine is added for sterilization to make drinking water.
The International Space Station (ISS) flies at an altitude of 400 km. About six astronauts are staying there. The interior of the ISS is kept at 1 atmospheric pressure, the same as on the ground, and the environment control and life support system ECLSS (Environmental Control Life Support System) maintains the temperature and humidity by purifying the air and water you need to bring with you. Is required. Human lungs are designed to breathe air with an oxygen partial pressure of 0.2 atm. The space station is filled with the same ratio of nitrogen and oxygen as on Earth. Nitrogen and oxygen for the station will come from the ground.
NASA's water electrolysis equipment (OGA: Oxygen Generation Assembly) generates oxygen through water electrolysis, and since hydrogen is dangerous, it is exhausted into space. It consumes oxygen and expels carbon dioxide into the cabin, increasing the carbon dioxide concentration. The concentration of carbon dioxide on Earth is about 350ppm-400ppm, but inside the ISS it is more than 4000ppm, about 10 times higher than on the ground. On the Space Shuttle, LiOH was the main device for carbon dioxide removal, but on the ISS, it is used as a backup in an emergency.
2LiOH+CO2 -> Li2CO3+H2O (1)
LiOH canisters need to be replaced frequently, and regenerative air purifiers are required for long missions. CDRA (Carbon Dioxide Removal Assembly) is a carbon dioxide removal device in the United States. After passing through a filter, the air is dehumidified in an adsorption column containing silica gel and then passed through a zeolite adsorption column. Carbon dioxide is adsorbed by the zeolites, while oxygen and nitrogen pass through. When the zeolite adsorption column is saturated with carbon dioxide, the saturated adsorbent is heated to desorb the absorbed carbon dioxide and discharge it overboard. Since the CDRA has two adsorption units for carbon dioxide, continuous operation is possible because one adsorption unit can adsorb carbon dioxide during the regeneration process in which the other unit is heated to release carbon dioxide. In the initial operation of the ISS, oxygen was generated by water electrolysis, and hydrogen was exhausted into space. On the other hand, the carbon dioxide in the cabin is also separated and concentrated and thrown into space. Couldn't we get something useful out of this discarded water and carbon dioxide? The idea to solve it is the idea of generating water by the Sabatier reaction. NASA has a Sabatier reactor to reduce the CO2 emitted by the three to produce water. Oxygen is produced by electrolyzing the water. The chemical formula of the Sabatier reaction is as shown in formula (2), and the oxygen contained in carbon dioxide is the oxygen contained in water.
CO2 + 4H2 -> CH4 + 2H2O (2)
Plants absorb carbon dioxide and produce oxygen on the ground, but on spacecraft, the air is regenerated using physicochemical methods.
water in a spaceship
The average American consumes 605 liters of water per day. Space station crews live on about 3.5 liters of water a day.
The urine processor UPA (Urine Processor Assembly) is mainly mounted on WRS rack 2 and recycles urine into drinking water. The principle of urine processing is to heat water containing urine with a heater to generate steam. The most important part of this process is the Distillation Assembly (DA). The boiling point is lowered by reducing the pressure inside to 0.048 atm. Urine is rotated at 220 rpm in a cylindrical heater, centrifugal force pushes the liquid inside the cylinder, and vapor is collected from the center and taken out as distilled water. Non-volatile impurities do not evaporate, so 97% can be removed, but ammonia and alcohol volatilize. Volatile components are oxidized by an oxidation catalyst, treated with an ion exchange resin to produce pure water, and iodine is added for sterilization to make drinking water.