Which outcome limits operational efficiency of hydrogen fueled internal combustion engines running lean?

💡 Explanation

When hydrogen engines run lean, a higher oxygen concentration leads to greater thermal efficiency and lower unburned fuel, but it significantly promotes the Zeldovich mechanism of NOx formation due to high flame temperatures and oxygen availability, hence limiting efficiency improvements. Therefore, increased NOx is the consequence, instead of faster flame, higher hydrocarbons, or valve corrosion which have different dependencies.

• Which constraint causes reduced efficiency when superheated steam undergoes gas-to-liquid phase transition in a turbine?
• Which mechanism causes increased coercive field strength in nanocrystalline magnets?
• Which outcome occurs when a microwave oven's magnetron tube operates with a significantly reduced magnetic field strength?
• Which risk increases when insufficient binding energy exists within fissile isotopes within a nuclear reactor's fuel pellets?
• Which outcome causes the energy splitting when degenerate atomic orbitals form molecular bonds?
• Which efficiency decrease results when a gas turbine cycle experiences turbine blade fouling?