Alternative Method for the Formulation of Surrogate Liquid Fuels Based on Evaporative and Sooting Behaviors

This study proposes a novel approach to design and evaluate surrogates for liquid fuels, aimed at replicating their evaporative and sooting behaviors. The method was demonstrated for a commercial heating oil. The lack of surrogates found in the literature for this relevant fuel, in addition to its physicochemical complexity, was the primary reason for its choice to test the proposed method. A first surrogate aiming to emulate the evaporative behavior of the target fuel was designed through the combination of a theoretical evaporation model and experimental tests. The second surrogate was formulated to replicate the sooting behavior of heating oil, whereas a third surrogate aimed to match the physicochemical properties relevant for both processes. The so-designed surrogates were validated afterward by means of single-droplet evaporation tests under high-temperature conditions. The obtained evaporation curves served as a benchmark for evaluating the evaporative characteristic, whereas an aspirating probe collecting all of the soot produced at a high-temperature and reducing atmosphere was used for the validation of the sooting tendency. It was found that surrogates specifically designed to match the evaporative and sooting behaviors of the target fuel displayed a remarkably good agreement when validated against experimental data for heating oil. Overall, the obtained results confirmed the validity of the methodologies proposed for surrogate formulation, combining predictive methods and droplet evaporation tests at high temperatures.