From design to operation: Integrated optimization of intermediate cycle heat exchange systems for aero engines

Advanced aero-engine thermal management systems increasingly rely on intermediate cycle heat exchange (ICHE) systems to enable safe and efficient heat transfer between fuel and high-temperature air. While the ICHE configuration offers significant safety and anti-coking advantages over direct-contact cooling, current research lacks a unified optimization framework that jointly addresses system weight and thermal performance in design, as well as thermal adaptability in operation. To fill this gap, this study develops an integrated optimization framework for ICHE systems in aero engines, encompassing both design-stage trade-offs and operational regulation. For system design, a coordinated multi-objective optimization model is constructed using total heat transfer area and system-equivalent thermal conductance as objectives, and solved via a hybrid algorithm combining genetic algorithms with gradient-based methods. The resulting Pareto front reveals the nonlinear coupling between weight and heat transfer performance, offering flexible design choices. For operational optimization, a transfer matrix-based model is developed for multi-branch ICHE configurations and experimentally validated using a platform with aviation kerosene, high-pressure water, and air. By adjusting the intermediate working fluid mass flow rate and its distribution, the system heat transfer rate is maximized, with results indicating the dominant role of mean temperature difference over thermal conductance. Operational optimization yields a 7.98% increase in heat transfer rate, demonstrating the framework's effectiveness. This work provides a comprehensive method for optimizing ICHE systems across the full engine lifecycle, offering valuable insights into high-efficiency, lightweight thermal management design and operation for next-generation aero engines.