Aviation has a significant contribution to climate change, which must be decreased. The A321 APPU could offer a substantial improvement, by introducing a hydrogen-powered Auxiliary Power and Propulsion Unit (APPU). This turboshaft engine is located in the tail cone and powers a b
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Aviation has a significant contribution to climate change, which must be decreased. The A321 APPU could offer a substantial improvement, by introducing a hydrogen-powered Auxiliary Power and Propulsion Unit (APPU). This turboshaft engine is located in the tail cone and powers a boundary layer ingestion propulsor, taking over 10% of the thrust. The Steam Injection and Recovery (SIR) cycle is introduced to improve the efficiency of the APPU. This semi-closed water cycle can reduce fuel consumption and NOx emissions. Both the baseline and SIR APPU are modelled in pyCycle, an open-source gas turbine parametric analysis tool. Water properties and heat exchangers are added so pyCycle can model the SIR cycle. The baseline APPU has a thermal efficiency of 45% and a mass of 502 kg. The SIR cycle can increase the efficiency by 1.54% and decrease the NOx emissions by 33.4%, at the cost of a 15.7% mass increase.
