These dryers use atomizers to feed liquid into the drying chamber. When the small droplets of liquid enter the room, they are exposed to the hot air and the water evaporates the device into powder. The hot air is supplied by an indirect air heater or a direct air heater. Since the use of air heaters depends on the thermal sensitivity of the feed, indirect combustion air heaters are usually used in the food, pharmaceutical, and dairy industries.
According to Wikipedia, "The hot drying gas can pass through the atomizer in a cocurrent or countercurrent direction. The cocurrent flow makes the particle system have a shorter residence time and the particle separator operates effectively. The countercurrent method makes the residence time of large particles The room is usually equipped with a fluidized bed system".