Study and development of a mini-tube gas separator utilizing the Soret effect

The Soret effect is a phenomenon in which a temperature gradient gives rise to a concentration gradient. In this study, we attempted a simple technique for the separation of hydrogen from a gas mixture by utilizing the Soret effect. A gas mixture of hydrogen and carbon dioxide was introduced into a metal mini tube in which a temperature gradient was established in the direction normal to the flow. The experiment demonstrated that hydrogen was actually separated from the gas mixture, although the separation was very small with the present apparatus. From results of the experiments and computational fluid dynamics (CFD) analysis, we believe that the layer of high hydrogen concentration that moved toward the heating wall was very thin. It would be necessary to extract the high concentration of hydrogen flowing near the wall to increase the separation efficiency.