Modeling and experimental validation of helium-based thermal management system with transcritical heat sink for hydrogen-fueled aero engines

Liquid hydrogen (LH 2 ) fuel offers a pathway toward decarbonizing aviation but introduces thermal management challenges arising from its cryogenic and chemically reactive nature. Intermediate cycle heat exchange (ICHE) systems employing a chemically inert intermediate fluid to decouple the cryogenic fuel from high-temperature air have emerged as a promising architecture. However, as the cryogenic working fluid traverses the pseudo-critical region, drastic thermophysical property variations propagate through the intermediate loop, producing a coupled nonlinear response that conventional analyses cannot capture. Existing transfer matrix-based formulations remain restricted to the constant-property regime, and experimental data on cryogenic ICHE configurations are scarce. Here, a helium-based ICHE system with transcritical heat sink is investigated through coupled modeling and experiment. A HEX segmental transfer matrix model is developed within a system-level analytical framework, recasting the nonlinear heat transfer under drastic property variation into a 2×2 coefficient transfer matrix. The model is validated on a cryogenic ICHE platform employing liquid nitrogen as a surrogate for LH 2 , with the predicted printed circuit heat exchanger (PCHE) heat transfer rate deviating from experimental data by only 1.46% and 87.1% of system-level predictions falling within the ±15% deviation band. Parametric analysis reveals that heat-source and cold-source boundary adjustments produce a global synchronous variation of the system temperature field, while the intermediate fluid mass flow rate serves as an independent means for redistributing thermal load between series-connected components. The framework provides a system-level modeling and design basis for thermal management of hydrogen-fueled aero engines.