The F-22 Environmental Control/Thermal Management System (ECS) represents a highly integrated application of thermal control technologies in a tactical aircraft. Its 135 components and integrated software comprise an air cycle refrigeration pack, two liquid cooling loops, vapor cycle pack, and active fuel cooling.
The two liquid cooling loops use polyalphaolephin (PAO) as a working fluid. They function to remove heat from essential equipment and transport that heat to the fuel system. The fuel system then rejects heat to ram air via two fuel coolers or sends the fuel to the engine to burn.
Reliable and lightweight fluid transport was a key design focus for these cooling loops. This paper discusses the system design evolution of the F-22 ECS fluid transport equipment from its original concept to the current system architecture.