Numerical Study of Adsorption–Desorption Dynamics in a Desiccant Compressed-Air Dryer

Efficient moisture removal from compressed air is essential to prevent corrosion, freezing, and product defects in industrial systems. Desiccant dryers can achieve low dew points while offering advantages in energy consumption and maintenance over refrigerated and membrane-based systems. Despite their practical importance, the coupled adsorption–desorption behavior in these systems has not been thoroughly modeled. This study develops a two-dimensional, transient computational fluid dynamics (CFD) model of a desiccant compressed-air dryer using ANSYS Fluent. The compressed air–water vapor mixture is treated as an incompressible ideal gas, and intraparticle mass transfer is modeled using a user-defined Linear Driving Force (LDF) approach. The model was validated against benchmark CO₂ breakthrough data and compressed-air experiments, showing good agreement with the measured humidity profiles and breakthrough times. The proposed model offers a robust framework for predicting dryer performance and optimizing energy-efficient operation of compressed-air drying systems.