The amount of air needed for cooling depends on diameter of pellet:

• pellet, diameter 2 - 4 = 1.2 m3/kg/h
• pellet, diameter 5- 7= 1.4 m3/kg/h
• pellet, diameter 8 - 11 = 1.5 m3/kg/h
• pellet, diameter 12 - 16 = 1.6 m3/kg/h
  

Cooling time:
Time of staying pellets in cooler depends on dimensions of pellet. For example, for a pellet of diameter about 5-7mm it is 15 min.

It is very important to remember, that speed of air flow wouldn’t be more than 1 m/s for small pellets and 1,2 m/s for big pellets.