Technical Paper
A Direct Contact Membrane Separator for Diver Rebreather Carbon Dioxide Transfer to Seawater
1998-07-13
981671
Gas-permeable membranes that continuously transfer carbon dioxide (CO2) from air to water were investigated in an effort to bypass the operational limitations of expendable solid absorbents currently used for CO2 control in closed-circuit underwater breathing apparatus (UBA). Rebreather UBA CO2 control requirements and known membrane properties were used to create a functional hierarchy of membrane types and CO2 transfer mechanisms, from which one membrane configuration was selected for evaluation. This Direct Contact Membrane Separator (DCMS) employs microporous hydrophobic Hollow Fiber Membrane (HFM) modules to create large membrane areas in small volumes for air-water phase contact without intermixing. Since the micropores in the hydrophobic walls of the hollow fibers are air-filled, gas permeation rates through this membrane are far higher than for any solid or liquid membrane.