Investigations into the Apparent Heat Release Rate of Neat Aerospace Fuels F-24, Iso-Paraffinic Kerosene (IPK) and Fischer-Tropsch Synthetic Kerosene (S8)

Abstract

Investigations were conducted into the thermophysical properties, Ignition Delay (ID), Combustion Delay (CD), Derived Cetane Number (DCN), and the Apparent Heat Release of neat aerospace fuels Jet-A, F-24, Iso-Paraffinic Kerosene (IPK), and Fischer-Tropsch Synthetic Kerosene (S8). The aviation industry is one of the largest producers of greenhouse gas emissions and due to increasing concerns regarding global warming, it is becoming increasingly urgent to find cleaner alternatives to the distillation process of crude oil. An investigation into the combustion and properties of fuels from different sources and production processes is required in order to mitigate climate change and reduce the demand for fossil fuels. The spray development and atomization of the fuels were analyzed with a Malvern Spraytec He-Ne laser based on Mie scattering theory. From this analysis, IPK was found to produce the smallest spray droplets, with a Sauter Mean Diameter (SMD) of 14.8 μm. Meanwhile, from the experiments in a Constant Volume Combustion Chamber (CVCC), the ID and CD of the fuels were analyzed for 15 combustion events. From the obtained ID and CD, the autoignition quality, or DCN, of the fuels was calculated. The ID and CD of Jet-A were 3.4 ms and 5.1 ms, F-24 was 4.1 ms and 5.8 ms, IPK was 4.9 ms and 15.5 ms, and S8 was 2.8 ms and 4.0 ms, respectively. The DCN for Jet-A was 47.0, F-24 was 43.4, IPK was 26.9, and S8 was 59.6, respectively. The peak pressure during combustion was analyzed, where S8 was observed to have the largest amount of peak pressure ringing at 42.7, while IPK had the lowest at 41.8, respectively. From the Apparent Heat Release Rate (AHRR) IPK was observed to have the longest Low-Temperature Heat Release (LTHR) duration releasing approximately 17.5% of its energy during this combustion phase. This long duration is due to the influence of ID and CD on the Negative Temperature Coefficient Region (NTCR). Additionally, IPK was observed to have little to no ringing after High-Temperature Heat Release.