Biofuels from cardoon pyrolysis: Extraction and application of biokerosene/kerosene mixtures in a self-manufactured jet engine

The present work reports on the study of biofuel production from biooil obtained by cardoon pyrolysis (Cynara cardunculus L.). The main process was carried out at 700 °C and at 50 cm3 min−1 nitrogen flow rate for 1 h. The liquid yield in such pyrolysis process was 38.91% (wt/wt). Two solvents were used for biofuel extraction, namely ethyl ether and ethyl acetate, to achieve a 34.72% yield in biofuel. Subsequently, a distillation process in the range of kerosene (200-275 °C) was performed to finally obtain “biokerosene”, which was used to feed both a self-manufactured jet engine and an internal combustion engine (ICE). In the jet engine, experimental tests were run for four kerosene/biofuel mixtures in the range 0-20% biofuel, in atmospheric conditions (20 °C and 1015 mbar) and setting the engine in a slightly sloped arrangement in order to prevent excessive displacements. Fuel pressure at maximum power was recorded as 6 bar, which yielded 0.00252 kg s−1 fuel flow rate. Results -even for the mixture with 20% biofuel content- were found to be similar to those for pure kerosene. The turbocharger yield was 74% with 200,000 rpm and 0.091 kg s−1 air flow rate for all conditions, which equates to an approximate power of 100 hp for the use of the turbocharger in self-propulsion. On another note, the ICE was operated using a 80-20% diesel-biokerosene mix and was observed to show a satisfactory behaviour in terms of torque and power yields. The use of such biofuels to feed jet and ICE engines represents an excellent alternative to fossil fuels, and therefore quality improvement is a key topic for further research in the area.