Combustion of Methanol, NH ₃ , and NH ₃ /H ₂ Blends in a Constant Volume Chamber with an Energy-Enhanced Igniter

This contribution focuses on the effect of an energy enhanced igniter based on breakdown-transient discharge principles on fuel combustion efficiency using a shadowgraphy technique with the constant volume combustion chamber. The experimental results of visualized ignition characteristics indicated that the energy-enhanced igniter markedly increased flame propagation speed across various ignition voltages, with the most substantial enhancement observed at 800 V. The igniter also significantly improved combustion performance under low initial temperature conditions. Moreover, it achieved the greatest increase in combustion efficiency for ammonia–air premixed mixtures under both varying initial pressures and lean combustion conditions. These findings provide valuable insights for enhancing the combustion efficiency of ammonia-fueled engines and reducing carbon emissions.