Superiority Analysis of the Ammonia Fuel Turboprop Engine with Regenerative Heater for Regional Aviation

This paper proposed a turboprop engine utilizing ammonia as fuel and incorporated a recuperator. Firstly, by referring to the Saab 340B aircraft and its engine CT7-9B, a typical aircraft flight mission model, thrust demand calculation model, and classic turboprop engine model were sequentially developed. Immediately, the established engine model was cross-verified with the simulation outcomes of commercial software GasTurb, revealing a calculation error margin of approximately 5%. This confirmation verified the precision and reliability of the model's calculations. Subsequently, ammonia was substituted for the engine fuel, then the updated engine model was seamlessly integrated with the aforementioned aircraft flight mission model and thrust demand calculation model, serving as the benchmark model for the aircraft and its engine. In addition, this paper conducted the thrust demand analysis of the benchmark model in typical flight stages, including takeoff, climb, cruise and landing, and thus achieved the matching of engine working condition as well as the calculation of ammonia fuel consumption for each flight stage. The calculation results revealed that the takeoff and climb stages exhibited the peak fuel demand per unit time, whereas the cruise stage contributed to about 70% of the total fuel consumption throughout the entire flight mission. Based on the above work content, the paper incorporated a serpentine tube heat exchanger model as the regenerator which adapted to the size of the engine model, using the logarithmic mean temperature difference (LMTD) method to simulate the authentic heat transfer process and flow resistance loss. Consequently, a comprehensive model scheme with a regenerator was established, then the paper computed its thrust requirement, engine performance, and ammonia fuel consumption for each stage of the aforementioned typical flight state. The computation findings indicated that, in comparison to the benchmark scheme, the scheme with a regenerator could achieve a noteworthy reduction of approximately 2.23% in fuel consumption during cruise stage, thereby demonstrating a significant energy-saving effect. Furthermore, this paper explored the influence of heat recovering efficiency on both the regenerator's weight gain and the engine's fuel consumption, utilizing the temperature increase of ammonia fuel due to the regenerator as the evaluation metric for heat recovery. The result showed that during the cruise stage, as the fuel temperature rise elevated from approximately 41K to 113K, the regenerator's mass would increase from about 0.75kg to 1.07kg, concurrently, there would be a substantial improvement in fuel efficiency, with savings increasing from approximately 0.7% to 3.6%. The ammonia-fuel turboprop engine with a regenerative heater exhibited significant environmental friendliness and notable economic advantages. It has the potential to apply in the regional aviation sectors.