Direct Contact Air Revitalization

Spacecraft air must be treated to control the concentrations of carbon dioxide and other contaminants while also controlling oxygen concentration, humidity and temperature. These requirements in a low gravity environment currently lead to complex systems requiring substantial volume and mass. A direct liquid contact system can be used to contact recirculation air with small liquid droplets to control humidity and temperature, while managing the concentrations of carbon dioxide and other air impurities. The absorbent liquid concentration and temperature, combined with the recirculation rate can be used to independently control temperature, humidity, and carbon dioxide concentrations. The absorbent liquid is removed from the air stream using a centrifugal separator, and carbon dioxide is vented or chemically pumped to a higher pressure receiver for reuse. This integrated system has potential for reduced energy, volume and mass, relative to more conventional combination of adsorbents and air conditioning. The chemistry of the absorption system, properties of the absorbent liquid, and its integration direct contact air purification into the environmental control system is discussed.