Traditional jet aircraft use engine compressor bleed air to power their Environmental Control Systems (ECS). The ECS conditions this hot, high-pressure bleed air to provide a comfortable cabin environment. Collins' bleed-free ECS produces its own hot, high-pressure air via electric air compressors. Jet engines can be more efficient when providing power to ECS electrically instead of pneumatically. Collins replaced bleed with electrical power to condition a commercial aircraft cabin, carts and cargo. Collins electric compressors replace bleed air in the electric pack architecture. Electric compressors require unique architectural considerations. Electric architecture enables efficiency gain by depowering the ram fans in flight. Replacing bleed-powered air cooling with electrically powered Vapor Cycle Systems (VCS) improves efficiency. A modular Supplemental Cooling Unit (SCU) design improves aircraft maintainability. A modular Galley Cooling Unit (GCU) design speeds aircraft assembly. Vapor cycle cargo cooling offers improved efficiency compared to one with engine bleed air. High power density electronics may require liquid cooling. The Cabin Pressure Control System (CPCS) remains conventional despite the bleed-free ECS. The dedicated Nitrogen Generation System (NGS) air source reduces system contamination in service. In summary: Electrically powered ECS can be more efficient than bleed powered ECS for certain aircraft types. Collins designed electric air compressors to replace bleed air on commercial passenger aircraft. Transferring some of the aircraft thermal load from air cycle cooling to electrically powered vapor cycle cooling can improve efficiency. Extending electric vapor cycle cooling to cargo systems may provide similar benefits. Inert gas generation systems (NGS) may benefit from clean air provided by electric air compressors in lieu of engine bleed air. Extensive deployment of high power electric architecture may require the added complexity of a liquid cooling system.
This is a publication from the International Aircraft Cabin Air Conference 2024 (London, 17-18 September 2024)