Water Solubility in Different Alternative Jet Fuels: A Comparison with Petroleum-Based Jet Fuel

The paper presents an extensive assessment of the hygroscopic characteristics of a number of alternative jet fuel blends. These are blended with conventional Jet A-1 to conform with current aviation standards at a 50:50 ratio by volume, except for DSHC (Direct Sugar to Hydrocarbon), which is blended at 10% DSHC and 90% Jet A-1. Given the lack of information available on the water solubility of alternative jet fuels, an effective analysis of experimental data about this characteristic in six different alternatives was performed. These included four ASTM approved alternatives (two Fischer-Tropsch (FT) synthetics from coal and natural gas, one HEFA (Hydroprocessed Esters and Fatty Acids) derived from camelina and DSHC. An extra two alternatives currently under consideration for ASTM approval were also tested; ReadiJet and an ATJ (Alcohol to Jet). Water solubility-temperature curves were created and compared to the Jet A-1 reported in the CRC (Coordinating Research Council) Handbook of Aviation Fuel Properties. All samples were subjected to a temperature range of −20°C to 50°C, significantly wider than that illustrated in recent studies and the CRC Handbook. The preliminary results suggest that the alternative fuel blends followed a different pattern to the CRC Jet A-1 for water solubility at different temperatures. Unlike the conventional fuels, the curves did not fit an exponential trend. The preliminary results need to be verified to assert confidence in the results with further testing. The results for the water absorption between −20°C and 50°C for each alternative blend were measured and it was found that DSHC:Jet A-1 absorbed the most water, and ReadiJet:Jet A-1 the least. Further work is planned to validate the trends observed.