Material Preparation
A dry air dryer is a closed-loop dryer that first passes the air through a molecular sieve (desiccant) bed to remove its moisture, then heats it and delivers it to the drying hopper. The dew point of the air it produces falls to levels of down to −40 °C; this dry air draws the moisture out of the inside of hygroscopic granulate. The difference from a hot air dryer is that the air is dry as well as hot.
Two desiccant beds work alternately: while one supplies dry air to the process, the other gives off its moisture with regeneration heat. That is why the dryer's regeneration heater is a separate energy item and remains invisible in the energy calculation.
Capacity selection starts with consumption: hourly consumption × drying time ÷ bulk density gives the hopper volume; the air flow in connected systems requires about 1.9 m³/h per kg/h. A hopper larger than necessary leads to over-drying — PA yellows, TPU degrades.
A hot air dryer heats ambient air and delivers it; it only removes surface moisture (PE, PP, PS). A dry air dryer first dries the air and then heats it; it draws out the moisture inside the granule (PA, PC, PET, ABS).
The dryer selection tool calculates the hopper volume and air flow according to the material, consumption and regrind share, and lists the suitable Ferlin models with the real residence time.