Performance assessment of a Multi-fuel Hybrid Engine for Future Aircraft

This paper presents performance assessment of the proposed hybrid engine concept using Liquid Natural Gas (LNG) and kerosene. The multi-fuel hybrid engine is a new engine concept integrated with contra rotating fans, sequential dual combustion chambers to facilitate “Energy Mix” in aviation and a Cryogenic Bleed Air Cooling System (CBACS). The current analysis focuses on three aspects: 1) effects of the CBACS on the HPT cooling air requirement and the associated effects on the cycle efficiency; 2) performance optimization of the hybrid engine; 3) assessment of the emission reduction by the hybrid engine. An integrated model framework consisting of an engine performance model, a turbine cooling model, and a Cryogenic Heat Exchanger (CHEX) model is used to perform the analyses. The parametric analysis shows that using the CHEX, the bleed air temperature can be reduced significantly (up to 600 K), which reduces the turbine cooling air requirement by more than 50%, while increasing the LNG temperature by 300K. Consequently, the cycle efficiency improves even further. Depending on the fuel flow distribution between two combustors. The CO2 emission from the hybrid engine is lower by 15% to 30%. The mission analysis along with the Multi-Fuel Blended Wing Body aircraft shows a reduction in NOx emissions by 80% and CO2 emission by 50% when compared to B-777 200ER.