Session: 03-01 Hydrogen Combustion

Paper Number: 103247

103247 - Impact of Fuel Type on Aircraft Range: An Initial Optimization Study 

In order to reduce polluting emissions in aviation, liquid hydrogen fuel could replace kerosene currently used to propel aircraft. Aeronautics is today responsible for about 2.5% of global CO2 emissions. A recent report by the International Council on Clean Transportation released in October 2020 indicates that the average distance traveled by narrow-body aircrafts between 2013 and 2019 was 1350 km. Consequently, a majority of flights around the world are done by such narrow-body aircrafts. In addition, the data also shows that this type of aircraft is responsible for half CO2 emissions from all aircrafts. In other words, the narrow-body aircraft is responsible for most of CO2 emission in aviation. It is thus a central focus of this article.

Liquid hydrogen aircraft fuel tanks volume and mass evaluations are a critical challenge for the future zero emission aircraft. One first needs to consider the heat release per mass vs per volume for hydrogen and the consequences in term of tank volume. Considering an aircraft with 21 487 kg of kerosene fuel aboard, the corresponding volume taken is V = mass/density = 21487/800 = 27 m³ of tanks. For hydrogen, one thus expects to need a mass of 7700 kg of liquid hydrogen to keep the same thermal power as the heat released by combustion between hydrogen and kerosene is roughly 2.8 time higher per kg of fuel. This leads to a tank volume of 110 m³ nearly four times that for kerosene, as the density is roughly 11 times less for hydrogen. One very important aspect, though, is to also consider the aircraft range rather than only those previous estimates. For a 6300 km range, one can shows with the Breguet range equation that there is a factor 3.6 (4*0.9) and not 4 between a kerosene and LH2 aircraft tank volume. And this factor is obtained without considering the global effect of mass reduction on the aircraft structure itself due to lower fuel mass for LH2 aircraft, the subsequent aerodynamics lift (L) and drag (D) reduction, thus the power requirement reduction and then the fuel requirement reduction. In addition, the maximum take-off weight (MTOW) of the aircraft will also be reduced.

This article presents a method for estimating key parameters to travel a given range by a retrofitted A320 fed by liquid hydrogen engines. These parameters include: the mass of liquid hydrogen required, the corresponding fuel flow rate, and both the tank volume and mass. A model is developed and presented here to calculate these variations in key characteristics.

The results obtained through this program show that it would take about one ton of cryogenic liquid hydrogen, corresponding to a volume of 15 m³, in order to travel a distance of 1500 km for a narrow-body aircraft, and thus to cover a significant part of the worldwide flights used for an average distance of 1350 km. This volume is roughly twice below the current volume available on a narrow-body aircraft.

These results confirm that retrofitting an A320 powered by liquid hydrogen would be possible to cover a large part of daily flights and are encouraging for the use of liquid hydrogen as a future aviation fuel. This method can also be extrapolated to long range aircrafts or other fuels to determine estimate of the amount of LH2 required.

Presenting Author: Hugo de Nercy University of Tennessee Space Institute

Presenting Author Biography: Hugo de Nercy-Maingard is an engineering student from France. He studied aeronautical engineering for 5 years at ESTACA and specialized in engine and energy system integration. He graduated ESTACA this year in 2022. In addition, he’s currently doing a specialized master’s degree at ISAE-SUPAERO this year in order to learn even more about aerospace propulsion.

Authors:

Hugo de Nercy University of Tennessee Space Institute
Paul P. Palies University of Tennessee Space Institute