Advanced Thermal Management for High-Efficiency Engine Cycles

The commercial aviation industry is undergoing a transformative shift toward more efficient and sustainable propulsion systems. Emerging engine architectures such as hybrid-electric, all-electric, and advanced non-electric cycles with recuperation and intercooling promise significant improvements in fuel efficiency, emissions reduction, and operational costs. However, these next-generation propulsion systems generate higher thermal loads and rely more heavily on thermal technologies than conventional gas turbine engines. Hybrid-electric and all-electric propulsion systems introduce new thermal management challenges. High-power-density electric motors and battery systems generate concentrated heat that must be efficiently dissipated to maintain safe operating temperatures and prevent performance degradation or premature failure. NASA-funded research on electrified propulsion has identified that current electric motors achieve approximately 2 kW/kg, with 2035 projections reaching 9-16 kW/kg, while power electronics are projected to reach 9-19 kW/kg [1]. All these electrical components generate waste heat requiring effective thermal management. Lithium-ion and next-generation battery chemistries are particularly sensitive to temperature, with performance, cycle life, and safety all critically dependent on maintaining optimal thermal conditions. Advanced gas turbine cycles, such as intercooled and recuperated cycles, offer the potential for substantial fuel efficiency gains by recovering waste heat from the turbine exhaust. Historical NASA studies found that recuperated cycles with heat exchangers operating at 80-85% effectiveness could theoretically reduce fuel consumption by 15% [2]. However, realizing these efficiency improvements in aviation applications requires compact, lightweight heat exchangers capable of operating at high effectiveness while withstanding the demanding temperature, pressure, and vibration environment. Past implementations faced severe weight penalties adding 60% to engine weight and 70% to engine volume which eliminated the theoretical benefits [2]. Recent studies using compact heat exchangers have reduced the weight and volume penalty, but further improvements are needed for these cycles to become feasible. Current thermal management solutions developed for ground-based applications are often inadequate for aviation due to weight, volume, reliability, or performance constraints. NASA research has also shown that engine bypass streams are highly sensitive to pressure losses from thermal management hardware, making low-pressure-drop designs critical [3]. NASA seeks innovative thermal management devices, systems, and strategies that can enable high-efficiency engine cycles for commercial aviation applications while meeting stringent aviation constraints.