NH3 - The Optimal Alternative Fuel

In recent decades, the depletion of fossil fuels and strengthening of emission regulations has attracted increasing attention to the study of al- ternative fuels. One of the prospective alternative fuels is ammonia (NH3), demonstrating many favourable properties: (a) it is free of CO2, SOx, and soot emission because no carbon is present in the fuel; (b) it can be synthesized utilizing fossil fuels (e.g. petroleum, coal, natural gas), or renewable sources (e.g. wind, solar, biomass, manure); and (c) it can be easily and economically stored and transported in the liquid phase in large quantities via existing infrastructure. This present study investigates NH3 as a fuel, conducting experiments (using a single-cylinder spark-ignited research engine) for further automotive implementation.
The first part of this study investigates the Minimum Ignition Energy (MIE) requirements of NH3 and NH3 blend fuels (in order to counteract NH3’s unfavorable combustion properties where fuel enhancers such as H2 and gasoline are used). The single-cylinder engine is equipped with an electronic dual-fuel injection system, data acquisition system, and exhaust gas analyzer. NH3 will be introduced through the primary fuel line and different fuel enhancers from the secondary line. A long intake manifold will ensure proper mixing takes place before the fuel blend mixture enters the combustion chamber. Different spark plugs are used to change the ignition energy input. Different values of MIE at various NH3 concentrations have been measured. The MIE requirement for lean NH3 + Air mixture is found to be close to 10mJ, which is consistent with previous studies.
Emissions from NH3 combustion play a crucial role in the development, thus dedicated research has been focussed in this area. The second part of this study concentrates on the exhaust emission characteristics. Char- acterisation of emission profiles of species such as HC, O2, H2O, NO, and CO2 is crucial in understanding combustion with ammonia fuels. For every NH3 concentration blend, different exhaust species HC, CO, CO2, O2, and NOx are measured and compared against emission standards. CO emis- sions were found to decrease but emissions of NOx and hydrocarbons were increased with NH3. This is expected as the high nitrogen content of the ammonia molecule.
The preliminary results show that NH3 can be utilized as an alternative green fuel and energy source. Finally, research and development of NH3 will be of increasing interest due to economic and industrial demands.