How does a counterflow heat exchanger work?

In the counterflow heat exchanger, two neighboring aluminum plates create channels for the air to pass through. The supply air passes on one side of the plate and the exhaust air on the other. Airflows are passed by each other along parallel aluminum plates instead of perpendicular like in a crossflow heat exchanger. The heat in the exhaust air is transferred through the plate from the warmer air to the colder air.

Sometimes, the exhaust air is contaminated with humidity and pollutants, but airflows never mix with a plate heat exchanger, leaving the supply air fresh and clean.