https://www.finfancooler.com/H....eat-Exchanger/Stacke
How Stacked Heat Exchangers Work
Typically, stacked heat exchangers are made up of fluid-flowing channels and alternating layers of plates or fins. Large surface areas for heat transfer are produced by the fins or plates, and effective heat exchange is ensured by the channels that let the fluids flow in different directions. It is possible to greatly increase the heat transfer surface area without appreciably expanding the exchanger's size by stacking several layers on top of one another.