Key technologies being studied are:
1. H2 Micromix combustion
Jet A-1 has relatively narrow combustion flammability limits which presents several challenges for low NOx combustion technologies. H2 is a promising fuel as it has much wider flammability limits enabling leaner (lower flame temperature) combustion. Additionally, the molecular diffusivity and high flame speed of H2 offer good mixing and lower residence times, therefore significant reductions in NOx are possible. Micromix (diffusion) combustion enables superior fuel and air mixing without the risks of auto-ignition and flashback associated with premixing. The improved mixing reduces local high flame temperature regions, leading to ultra-low NOx emissions. Within WP3, ultra-low NOx H2 Micromix combustion technology is being matured through a combination of numerical and experimental research comprising injector array, full annular combustor segment and altitude-relight studies.
2. Fuel system heat management
In order to exploit the formidable heat sink potential of LH2, to enable more-efficient disruptive propulsion technologies, WP2 is maturing technologies for compressor integrated cooling, intercooling and variable cooling concepts, fuel pumps, heat exchangers, turbines for expander cycles and cryogenic cooling for electric systems for turboelectric distributed propulsion. WP1 is maturing LH2 fuel tank design and integration.
In WP1, a suite of models is being developed to evaluate LH2-fuelled aircraft with respect to energy efficiency, emissions, life cycle CO2 and costs, for potential fuel price and emissions taxation scenarios. The benefits and economic viability of LH2 will be quantified relative to best-case scenario projections for Jet A-1, Biofuels and LNG. WP4 is generating best-practice safety guidelines for LH2 at aircraft, airport and operational level. WP5 will deliver comprehensive roadmaps for the introduction of LH2.