How does a sealed box in a sliding tray stripper allow air water mass transfer - is there an air circulation system?

Yes - a blower attached to the side of the stripper box is blows air upward through the holes in the trays. The air makes a single pass through the trays and is then exhausted out the top of the stripper.

When we say that the box is “sealed” in a sliding tray stripper, we’re referring to the lack of gasket seals around the body of the unit as you would have with a stacking tray stripper. Those gasket seals can become leak points over time as the trays are lifted off for cleaning and then restacked. By contrast, the sliding tray stripper box has a single gasket seal on the access door, and this requires minimal pressure to maintain a leak-proof seal.