# Evaluation of High Thermal Stability Fuels

Project Number: 066
Category: Aircraft Technology Innovation, Alternative Fuels

Preliminary theoretical investigations show significant reductions in fuel burn when high thermal stability fuels are used. This study will investigate if fuels with high thermal stability, when used as coolants or subjected to engine temperatures higher than currently realizable with typical conventional fuel thermal stability, result in fuel burn improvements in jet engines. Alternative jet fuels have shown improved thermal stability and are good candidates for this type of investigation. The research team will conduct a systematic and comprehensive study of the potential benefits of high thermal stability fuels in an aircraft engine and the impact of fuel composition on the thermal stability of alternative fuels. Work under this project will document bottlenecks for performance gains and quantify each potential gain and which hydrocarbon compositions that lead to the greatest benefit. From these identified bottlenecks, experimental campaigns will focus on testing of the theoretical work. The research team will also examine the benefits of utilizing alternative jet fuels as well as conventional fuels with changes in terms of their composition.

### Outcomes

Use of high thermal stability fuels has the potential for significant reductions in fuel burn and emissions. These fuels have higher heat-sink capability, and therefore, are good coolant candidates. The quantification and documentation of the thermal stability benefits will provide insight into this additional aspect as well. Unlike other research trajectories towards these goals, the improved thermal stability utilization is currently not as well characterized.

Thermal management of a jet engine is a vital aspect that ensures proper functioning and structural resistance for several engine components. Higher thermal stability fuels could reveal a redundancy of various engine components currently used in thermal management, leading to engine weight reduction, and in turn, fuel burn benefits. Moreover, higher thermal stability fuels may enable certain hybrid electric concepts where thermal management is a key challenge.