Thermal behaviour and combustion characteristics of JET A-1, HEFA-derived SAF and their blends for aeronautical applications

Abstract

The thermal behavior and combustion characteristics of aviation fuels are critical for engine performance optimization and sustainable aviation fuel (SAF) integration. However, there is a knowledge gap in understanding the thermal stability and combustion efficiency of HEFA-derived SAF (Hydroprocessed Esters and Fatty Acids Sustainable Aviation Fuel) and its blends compared to JET A-1. This study addresses this gap by evaluating the thermal and combustion properties of pure JET A-1 (J100), HEFA-SAF (HS100), and their blends (JxHSy) using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), supported by gas chromatography-mass spectrometry (GC-MS) for compositional insights. Results indicate that HS100 exhibits superior thermal stability, with degradation occurring between 100 °C and 205 °C, compared to J100's 85 °C to 168 °C range. TGA data show that HS100 degrades more gradually, while J100 undergoes rapid mass loss, suggesting differences in chemical composition. DSC analysis revealed that HS100 has a broader and higher exothermic peak (248 °C) compared to J100 (234 °C), supporting its cleaner combustion characteristics. Blended fuel samples demonstrated intermediate stability, with J30HS70 optimizing both thermal resilience and energy efficiency. GC-MS analysis showed higher paraffinic content in HS100 (79%) compared to J100 (55%), reducing soot emissions and improving combustion efficiency. However, HS-rich blends exhibited lower ignition and comprehensive performance indices, indicating trade-offs between cleaner combustion and ignition properties. This study demonstrated enhanced thermal stability and cleaner combustion characteristics of HEFA-SAF and its blends. It advances knowledge on fuel composition-thermal behavior relationships, offering insights into how SAF blending ratios influence combustion efficiency, ignition properties, and fuel system compatibility. By demonstrating that specific blends (e.g., J30HS70) optimize both thermal resilience and energy efficiency, this research contributes to refining fuel standards (ASTM D7566) and shaping SAF adoption strategies for commercial aviation.