4 ms·

Check Wikipedia, the article has examples: https://en.wikipedia.org/wiki/Countercurrent_exchange https://en.wikipedia.org/wiki/Countercurrent_exchange

• pfdietz 6y ago
  The page also talks about a variant, countercurrent multiplication. There's a really nice example of this in hydrogen isotope separation. The technique, called CECE (Combined Electrolysis Catalytic Exchange), was developed in Canada for production of heavy water and removal of tritium from heavy water. The centerpiece of the system is a catalytic exchange column. In the column, liquid water flows down, while hydrogen gas (of various isotopes) flows up. At each point, a wet-proofed catalyst promotes the exchange of hydrogen atoms between the water and the gas. In equilibrium, protium partitions more into the gas phase than into the liquid, so as the gas goes up the tower the heavier isotopes are stripped into the liquid phase and carried back down. At the bottom, the water is fed into electrolysis cells to produce gas to feed back into the tower. Over time, the water in the cells becomes enriched in heavier isotopes and can be tapped off. With this system, any H2 electrolysis plant could modified to also produce heavy water. This has troubling implications for nuclear proliferation in the coming "hydrogen economy", as heavy water reactors can be small and easy to hide, and have been used in the past for nations to enter the "Nuclear Club".