Colloquia

Samenvatting

Hydrogen-based aircraft propulsion technologies are being investigated as a low-emission alternative technology for cleaner aviation. Specifically, one of the potential hydrogen-based propulsion systems for future aircraft is based on hydrogen fuel cell-electric powertrains with low voltages and high transport currents. 

This thesis focuses on three aspects of hydrogen technology development for the energy transition in aviation:

In the first part, through an experimental study on superconducting CORC cables, the effect of current (im)balances between the constituting layers of the cable on the performance of the cable under Alternating Current (AC) conditions was investigated. Inductive sensors, based on pickup loops consisting of copper wire coils and copper lines printed on a PCB were placed around or adjacent to the cable. It was found that the measured induction voltages correspond well to previously developed current distribution models, forming a validation tool for these models and showing that such inductive sensor methods may be used to obtain useful information on current (im)balances in cables. Such current imbalances and their relation to cable loss and stability are important for cables intended to be used in aircraft powertrains with changing currents.

The second part involved modeling of a synergetic cryogenic cooling system for aircraft propulsion systems. In an aircraft where liquid hydrogen (LH2) fuel is stored at 20K, the hydrogen flowing towards a fuel cell may simultaneously be used to cool part of the electric powertrain to cyrogenic temperatures, improving their efficiency or enabling the use of superconductors, in turn allowing mass reduction. A closed-loop helium circuit functions as intermediate coolant between hydrogen and electric componenets. In this part of the thesis, a thermal system model was developed to simulate the thermal behaviour of this cryogenic cooling system. This provided a tool to study the influence of operational- and system parameters on component stability.

Thirdly, a broader system-perspective on low-emission aviation and the role for hydrogen herein was set up, based on a literature review and interviews with a number of companies and organizations involved in aviation R&D. This not only focused on technical aspects, but also on renewability-, infrastructural, economical, and organizational aspects. Hydrogen was compared to aviation bio-fuels, synthetic fuels and battery-electric aviation propulsion systems. Through this, the main opportunities and challenges for hydrogen within future aviation were identified.