Assessment of a hybrid propulsion system for short-mid range application with a low-order code

Abstract

The increase in air traffic expected in the next years must be accompanied by innovation to ensure the lowest possible environmental impact. Hybrid electric-thermal propulsion systems are currently being investigated and could represent a breakthrough for environmental sustainability in the sector. However, the transition to electric propulsion remains challenging due to the current level of energy density related to storage systems, the additional components associated with power conversion and control systems, not to mention the cost of all the associated equipment. The purpose of this study is to carry out a preliminary assessment of a hybrid propulsion system for a short-mid range aircraft. This study investigates the series hybrid configuration, where a turboshaft, a high temperature superconducting (HTS) electric motor, batteries and power converters interact to provide the necessary propulsion for flight. A zero-dimensional procedure is developed to estimate the mass and efficiency of the powertrain components for a selected flight mission. Thermal engines are modeled with the low-order code and coupled with the components of the electric system through a python routine. A comparison in terms of weight and emissions is reported for the designed hybrid propulsion system and the conventional one. The analysis shows that the weight of the two propulsion systems is similar but, the presence of batteries, even considering a higher level of technology than the current one, leads to a significant increase in the weight of the hybrid aircraft. The second part of the study focuses on pollutant emissions, showing that the hybrid system can reduce CO2 emissions by 58% and NOx emissions by 68% compared to the conventional system. Despite the excellent premise, the reduction in payload for the hybrid aircraft causes a reduction in pollutant emissions per passenger only for NOx. For this reason, further technological improvement is needed to make hybrid propulsion advantageous in terms of both payload and pollutant emissions.

Numerical Modeling of Lean Spray Lifted Flames in Inclined Multi-Burner Arrangements

“…The respect for the goals set by Flightpath 2050 [2] to cut down 75% of CO2 levels and 90% of current NOx emissions concerning the current standards could be reached only if new technologies will be developed. While pollutants such as carbon monoxide (CO) and unburnt hydrocarbon (UHC) can be handled through the improvement of the combustion efficiency, carbon dioxide (CO2) could be reduced only by improving the fuel consumption, and ultimately by employing alternative fuels and novel engines architectures [3][4][5][6]. Furthermore, the other main concern about aircraft pollution is represented by nitrogen oxides (NOx), which are promoted by high pressure and temperature [7].…”