From Drying & Cooling
Counterflow coolers are used for cooling pellets and extrudates to almost ambient temperature. The counterflow principle is the most efficient cooling system for both granulated products and meal. The cooling air flows through the cooler in the opposite direction to the product flow and the air temperature gradually rises from inlet to outlet, with a resultant even, gradual cooling of the product. This prevents pellet damage due to a great difference in temperature between product and cooling air. Modified (special) discharge systems are available depending on the specific application.