Evaluation of the energy and environmental impact of using Jet A1 and Jet A1-biojet blends with hydrogen as a dual fuel in a small turbojet engine

The depletion of petroleum reserves and the increasing environmental damage caused by petroleum-based fuels have accelerated the search for alternative fuels for the aviation sector. An effective way to lessen the aviation industry's environmental impact is to use hydrogen, a carbonless fuel, and biojet, which is made from biological raw materials. While the use of biojet and jet A1 blends as aviation fuels is widely investigated, there is a significant lack of research on the effects of dual-fuel combustion conditions with hydrogen. Therefore, in this paper, a small turbojet engine was operated at 50,000, 70,000, and 90,000 rpm with pure jet A1 and 61 % jet A1+ 39 % biojet blended liquid fuel as the primary fuel. Then, instead of liquid fuel, which was reduced to keep the engine speed constant, the performance and environmental impacts of dual-fuel combustion conditions were examined by adding hydrogen at flow rates of 50–200 l/min. Results indicated that jet A1 has somewhat higher performance, lower fuel consumption, and a higher environmental effect than the 61 % jet A1+39 % biojet blend in the experiments without hydrogen. However, the 61 % jet A1+39 % biojet blend has remarkably higher performance, lower fuel consumption, and environmental effect than jet A1 in dual-fuel combustion conditions with hydrogen at all speeds. The performance and fuel consumption improvement of jet A1 fuel in dual-fuel combustion conditions continues to increase with the hydrogen amount. Whereas, for a blend of 61 % Jet A1 and 39 % biojet, the effect of this improvement decreases after a hydrogen flow rate of 50 l/min. For both fuels, the improvement in environmental impact factors under dual-fuel combustion conditions increases continuously with the increase in hydrogen amount.