Integration of Circular Fins into Exhaust Gas Recuperators for Innovative Propulsion Concepts in Aviation

Overview

This investigation addresses thermal resistance limitations in exhaust-side heat transfer within the Water-Enhanced Turbofan (WET) concept's evaporator, a waste heat recovery system designed to meet 2050 aviation emission targets. The WET concept integrates an evaporator into aero engine exhaust flow to recover waste heat through liquid water evaporation, though industrial prioritization has diminished. The study focuses on modifying the heat exchanger architecture through annular finned tube bundle configurations to enhance exhaust-side thermal conductance.

Methods and approach

Three-dimensional computational fluid dynamics analysis was applied to evaluate a finned tube bundle configuration integrated into the WET concept's evaporator. The numerical investigation characterized local heat transfer coefficients and flow field behavior across the finned tube arrangement. The analysis assessed thermal performance relative to baseline non-finned tube bundle configurations, with particular attention to fin effectiveness and overall heat exchanger capacity. Interdependencies between engine component integration and heat exchanger performance were considered within the computational framework.

Results

The finned tube bundle configuration achieved fin effectiveness of 10, representing a significant enhancement in heat transfer capability relative to non-finned baseline configurations. This effectiveness metric indicates substantial improvement in the thermal resistance of the exhaust-side flow path, the principal limitation previously constraining evaporator performance. The enhanced heat transfer translates to increased thermal recovery capacity without modification to the fundamental component geometry or integration constraints.

Implications

Integration of circular fins into exhaust-side heat exchangers demonstrates technical feasibility for reducing thermal resistance bottlenecks in waste heat recovery systems for advanced propulsion architectures. The reported fin effectiveness of 10 provides quantitative validation for design modifications applicable to other exhaust gas recuperator configurations beyond the WET concept framework. These findings support continued development of heat exchanger models that account for component-level interdependencies in full engine cycle analysis.

The results indicate that passive heat transfer enhancement through finned geometries can address the dominant thermal resistance barrier identified in previous WET concept evaluations. This approach enables improved waste heat recovery effectiveness while remaining compatible with constraints imposed by aerospace applications, including mass penalties and spatial integration requirements.