Compact, Reliable Air Dryer to Prevent Icing in Air Cycle Machine

ABSTRACT: Reducing the temperature of air exiting an Air Cycle Machine (ACM) is an effective way to increase the cooling capacity of Environmental Control Systems. However, this requires a colder turbine inlet air, which can increase the risk of icing in the upstream condenser. To mitigate this problem, we propose a compact, reliable air dryer to reduce the humidity of the air flow entering the turbine. The proposed dryer employs an aerodynamic process to enable the humid air flow to cool itself to a temperature low enough to condense water vapor and separate the condensate from the air flow. The resulting air flow has a dew point below the water freezing temperature, thus minimizing the risk of icing inside the turbine. The proposed dryer has high turndown ratios for its flow rate and outlet humidity. It has no moving parts and is compact and maintenance-free. In Phase I, we will develop analysis models to determine the optimum geometry of the air dryer, and build and demonstrate a proof-of-concept air dryer. In Phase II, we will design, build, and demonstrate the operation of the air dryer and deliver it to the Air Force for further evaluation and integration into an ACM. BENEFIT: The proposed air dryer will enable advanced military aircraft to provide additional cooling power to address the ever increasing thermal loads without increasing the usage of bleed air. The air dryer will enhance the reliability of environmental control systems. Commercial applications for the technology developed in this program include environmental control systems in more-electric aircraft, large-scale air compression systems dryer and other gas dehydration systems.