The use of pulsatile flow to separate species.

Pulsatile motion greatly enhances the mass transfer of a dilute species compared to that due to pure molecular diffusion. If two dilute species are present in a carrier, the mass transfer of the faster diffusing species may be higher, lower, or the same as the slower diffusing species. This depends on the time constants associated with the system and the ability of a species to remain in the fast moving portion of the flow field. The difference in the mass transfer of each species can lead to a separation that can be used in a number of processes including the removal of carbon dioxide from the air. This phenomenon is modeled in an open tube geometry and in the annular space between two concentric cylinders. In annular pulsatile flow, the effect of the inner cylinder being off center from the outer cylinder on the mass transfer and separation is also analyzed. Finally, experimental results are presented to prove the validity of the models and the separation that can be achieved using this process.