Ceramic Oxygen Generator: A Method for Extracting High Pressure, High Purity Oxygen from Spacecraft Cabin Air.

Ion Transport Membranes (ITMs) are ceramic membranes permeable to oxygen and only oxygen. They are capable of extracting pure oxygen from air, or other gaseous process streams that contain oxygen. For several decades, ITMs have been the subject of research: particularly for the supply of ultra-high purity oxygen and as a method for providing oxygen to zero emission power plants. ITMs have not been put into widespread practice. ITM devices have not been qualified for human spaceflight, and they have not been used to supply medical oxygen to hospitals. ITM oxygen generators have not seen widespread use because previous ITM systems suffered low production rates and high energy consumption. NASA, in partnership with American Oxygen, has developed a ceramic oxygen generator (COG) with substantially higher oxygen production rates, and substantially lower energy consumption than earlier systems. Three key elements are essential to increased production and improved energy efficiency: the cell stack, the thermal management system, and the oxygen delivery system. This paper describes recent improvements in these three elements, along with results of testing that demonstrates unprecedented system level performance. Two forms of this technology are in development: one form produces oxygen at pressures up to 1 MPa, another version produces oxygen at pressures as high as 20 MPa. The prototype described in this paper is designed for 1 MPa operations, but advances in cell stack manufacture, thermal management, and oxygen delivery apply to high pressure applications.