C5.3 - Cryogenic hydrogen exergy utilisation: Less heat rejection to ambient and more useable energy for propulsion

Motivation

Low-temperature polymer electrolyte fuel cell systems (FCSs) in comparison to combustion engines need to transfer comparatively large amounts of heat at comparatively low temperature to ambient via their cooling system. Heat exchangers used for transferring such rejected FCS heat to ambient may be placed in a so called ram air channels to enhance convective heat transfer. Thereby introduced parasitic drag power during flight requires a significant share of fuel to produce counteracting thrust power.

Cryogenic hydrogen is therefore typically utilized as FCS coolant heat sink, even though such heat transfer destroys most hydrogen exergy. This project therefore investigates cryogenic exergy utilisation systems (CEUS) which convert a fraction of FCS waste heat partly to electrical or mechanical energy and use the remaining part for hydrogen conditioning. By using a CEUS, less heat has to be transferred to ambient and more energy for propulsion may become available - depending on CEUS size and mass.

Further application fields of this research

• hydrogen combustion drives
• trucks using liquid hydrogen
• on-ground hydrogen regasification
  • hydrogen transport in liquid form, pipeline feed
  • hydrogen refueling stations
  • boil-off gas management
• regasification of other cryogens, e.g. LNG, LIN, LOX

Members

Institute of Thermodynamics

M. Sc. Magnus Lenger

Dr.-Ing. Wilhelm Tegethoff (PI)

Prof. Dr.-Ing. Jürgen Köhler (PI)

Further reading

Lenger, M., Heinke, S., Tegethoff, W., Köhler, J.: Synergies of fuel cell system thermal management and cryogenic hydrogen exergy utilization. Scientific Reports 12, Article number 22065, 2022. http://www.nature.com/articles/s41598-022-26561-9