Integrated Design Optimization of Environmental Control Systems for Next-Generation Aircraft

The use of an electrically driven vapor compression cycle (VCC) for the environmental control system (ECS) of next-generation aircraft could substantially reduce fuel consumption. The renovated interest in this technology is due to the advent of new refrigerants featuring low global warming potential and the latest developments in high-speed centrifugal compressors and ultracompact heat exchangers. This paper documents the development of an integrated design optimization method for aircraft ECS, whereby the system-level design is performed along with the preliminary design of its main components. The methodology is used to perform the multipoint and multi-objective design optimization of a bleedless air cycle machine (ACM), i.e., the state-of-the-art ECS installed onboard the Boeing 787, and an electrically driven VCC system for a single-aisle, short-haul aircraft. The performance of the two optimal architectures is compared, showing that the VCC system is characterized by lower weight and electric power consumption than the bleedless ACM but features a higher drag penalty. Overall, the optimal VCC system leads to an 18% reduction in fuel weight penalty with respect to the bleedless ACM for the prescribed application.