Ignition and combustion study of premixed ammonia using GDI pilot injection in CI engine

In this study ignition of premixed ammonia was tested using a compression-ignited (CI) pilot fuel. n-heptane (C7H16) used as fuel, injected with GDI injector, enabling very small fuel injections. With setup, the engine run up to 98.5 % energy from – higher than seen in other CI-engine studies at time writing. The contribution varied 80–98.5 %, while keeping total λ-value constant. An important result observed an increase combustion efficiency 81%–90% due lower local ammonia–air mixture, indicating that for ammonia-ignition easily ignitable mixture is preferable compared strong injection. Lean mixtures showed gap heat release between and phases, which lowered efficiency. Increased led reduced ammonia-slip N2O-emissions increased NO-emissions, CO-formation better oxidation.