Cryogenic Fuel Storage Modelling And Optimisation For Aircraft Applications

Designing commercial aircraft to use liquid hydrogen (LH2)
is one way to substantially reduce their life-cycle CO2 emissions.
The merits of hydrogen as an aviation fuel have long been
recognized, however, the handling of a cryogenic fuel adds
complexity to aircraft and engine systems, operations,
maintenance and storage. The and fuel tanks could account for
8-10% of an aircraft’s operating empty weight, as such
designing them for the least added weight is of high significance.
This paper describes the heat transfer model developed in
the EU Horizon 2020 project that is used to predict heat ingress to a cylindrical tank with hemispherical end caps with external foam insulation. It accounts for heat transfer according to the state of the tank contents, the insulation material properties, the environment and the dimensions of the tank. The model also estimates the rate of pressure change according to the state of the fuel and the rate at which fuel is withdrawn from the tank. In addition, a methodology is presented, that allows for tank sizing
taking into consideration the requirements of a design flight
mission, the maximum pressure developed and the fuel
evaporated.
Finally, the study demonstrates how to select optimal
insulation material and thickness that provides the lightest
design for the case where gaseous hydrogen is not vented and
when venting during cruise is applied, leading to gravimetric
efficiencies as high as 74%.