This conference paper was submitted for presentation at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

The rapid decarbonization of industry and transport is a central challenge to the transition to a more competitive and greener economy. Hydrogen is seen by many as an energy vector with potential to decarbonize industries such as aerospace and heavy goods transport which cannot be easily electrified. In these sectors which need a higher energy density than is available from existing battery technology, hydrogen is likely to play a significant role in the decarbonization strategy. Whereas gaseous hydrogen in high pressure storage tanks is a feasible solution for ground-based and water-based transport, the associated weight penalty of high pressure tanks makes it less suited for the aerospace industry, where liquid Hydrogen is the preferred alternative. In order to utilize the hydrogen as fuel, either by producing electricity in fuel cells, or otherwise burning it in gas turbines, it is required for it to be evaporated and then brought up in temperature. This requirement is derived for a number of reasons, including, safety, integrity, and efficiency of the propulsion system. One option is to utilize excess produced by the powerplant and through a thermal management system redirect that heat to evaporate the LH2. This approach has, in the past, been used in traditional hydrocarbon-fueled aerospace propulsion systems. The Clean Aviation NEWBORN program has been awarded to develop a megawatt propulsion system with hydrogen as its energy source and develop it to TRL level 4. As part of this program, the consortium are developing the thermal management system which utilizes excess powerplant heat to thermally condition the hydrogen prior to entering the fuel cell. This paper outlines the development cycle of a liquid hydrogen evaporator heat exchanger; with a focus on the role of simulation in determining key design features necessary order to meet the stringent requirements over the wider operating envelope of the device. Insights into the thought process behind selecting the right simulation approach and stepping through complexity are given. Solutions necessary to minimize the risk of icing of the heating fluid are presented, in the form of both operating requirements as well as geometrical design of the device. Assessments conducted to verify that the large thermal gradients does not compromise the structural integrity of the device are also summarized. The key performance metrics, related to the efficiency and integrity of the evaporator are also outlined. Finally, the paper summarizes the performance testing conducted and test results obtained which validated the design, ahead of it being integrated into the thermal management system developed by the NEWBORN team.