Abstract
Proton Exchange Membrane Fuel Cell (PEMFC) powered propulsion is anticipated to play a leading role in decarbonising aviation. Megawatts of heat generated by PEMFCs must be transferred to atmosphere via cooling systems, and the drag incurred by these systems can be offset by heat dissipation to the airstream via ducted radiators, a phenomenon termed the ‘Meredith effect’. This phenomenon is relatively unexplored for ducted radiators on aircraft. This paper therefore presents thermodynamic analysis that provides unprecedented insight into the fundamental physics of the problem and demonstrates that it is feasible to develop fan-fed ducted radiators with low drag for 1 MW PEMFC propulsion systems at stack temperatures of 80 to 200 °C.
Parameters relevant to ducted radiators were analysed for several flight-representative cases to investigate their effect on specific thrust, and radiator exit temperature and frontal area. This detailed study enabled the duct and inlet fan assembly to be sized for zero internal drag. A multi-objective Genetic Algorithm was subsequently used to develop optimised radiators for this duct for 80 °C, 120 °C and 200 °C stack temperatures.
The results demonstrated that increasing stack temperature from 80 to 200 °C had several favourable effects: the radiator frontal area reduced by ∼55 %, the radiator core mass decreased from ∼8 kg to ∼3.6 kg, the fan assembly efficiency improved by ∼7 %, and the predicted external drag reduced by ∼36 %. The approach and findings from this study provide important information for the design and realisation of PEMFC powered aircraft propulsion systems.
Parameters relevant to ducted radiators were analysed for several flight-representative cases to investigate their effect on specific thrust, and radiator exit temperature and frontal area. This detailed study enabled the duct and inlet fan assembly to be sized for zero internal drag. A multi-objective Genetic Algorithm was subsequently used to develop optimised radiators for this duct for 80 °C, 120 °C and 200 °C stack temperatures.
The results demonstrated that increasing stack temperature from 80 to 200 °C had several favourable effects: the radiator frontal area reduced by ∼55 %, the radiator core mass decreased from ∼8 kg to ∼3.6 kg, the fan assembly efficiency improved by ∼7 %, and the predicted external drag reduced by ∼36 %. The approach and findings from this study provide important information for the design and realisation of PEMFC powered aircraft propulsion systems.
| Original language | English |
|---|---|
| Article number | 126697 |
| Journal | Applied Thermal Engineering |
| Early online date | 2 May 2025 |
| DOIs | |
| Publication status | E-pub ahead of print - 2 May 2025 |
Data Availability Statement
The data that supports the findings of this study are available within the article.Acknowledgements
The authors would like to thank Hydrogen Systems at GKN Aerospace for their financial and expert advice.Funding
This work was supported by the Hydrogen Systems team at GKN Aerospace, who are actively researching and developing hydrogen propulsion systems as part of a decarbonization strategy for aerospace. This includes the H2GEAR project, led by GKN Aerospace and supported by the ATI, which was launched in 2020 to develop scalable hydrogen electric propulsion systems for zero-carbon emission aircraft.