The biggest deciding factor when it comes to compressed air dryers is the need or desired dew point. As previously learned, refrigerated air dryers are capable of providing dew point of 3-5 °Celsius (37-41 °Fahrenheit), which is sufficient for most applications. However, if a process requires compressed air of higher quality, a desiccant dryer would need to be introduced into the system. Regenerative desiccant dryers are capable of achieving up to -70 °C (-100 °F) as standard, providing your compressed air system with clean and dry air. Unlike refrigerated air dryers, regenerative desiccant dryers utilize desiccant beads that adsorb the water vapors out of the compressed air. 

During the adsorption process, water vapors adhere to the desiccant bead without changing the composition of the desiccant. Once the desiccant beads get saturated with moisture, a process of regeneration occurs via dry purge air, heat or combination of both application to dry the wet desiccant. This type of a desiccant dryer typically uses a twin tower construction design, in which one tower dries the wet air, while the other tower regenerates and purges the moisture out of the desiccant beads.