Effect of Compression Ratio and Ignition Energy on Ammonia Premixed Combustion Process in a Single Cylinder Engine

Attempts in reducing CO2 emissions due to greenhouse gas effect with the help of a carbonfree fuel like the hydrogen and its derivate, ammonia, in the transportation sector are expected to increase. However, not only ammonia is toxic and corrosive due to its alkaline properties, but also the narrow flammability limits, the high auto-ignition temperature and the low flame velocity are the challenges to overcome for ammonia (NH3) fueled internal combustion engine. The combustion instabilities at low loads and / or high engine speed and unburnt NH3 emissions minimization are the key points to make NH3 a potential candidate as a fuel for premixed combustion engines. In this study, the spark ignited combustion of pure NH3 in a single cylinder engine, based on a compression ignition engine architecture, for different high compression ratios (CR: 16.4, 18.4 and 20) was evaluated as a function of combustion phasing and air fuel ratio in order to improve fuel consumption and engine stability. The experiments were performed over a wide range of operating conditions and the best hardware was defined mainly based on low-load improvement criteria. The experimental results addressed the combustion behavior with the exhaust gases emissions (NOX, and NH3) to state about the potential of using pure NH3 as a sustainable fuel on a diesel-like architecture engine.