Combustion and Emission Characteristics of Ammonia-Blend Fuels

In recent decades, the depletion of fossil fuels and strengthening of emission regulations has attracted increasing attention to the study of alternative fuels. One of the prospective alternative fuels is ammonia (NH3), demonstrating many favorable properties. This present study investigates ammonia blend fuel (i.e. ammonia-gasoline) for its practical automotive implementation. Experiments were performed using a single-cylinder spark-ignited research engine, which has been modified to accommodate ammonia duel fuel injection. The experiment setup is equipped with single cylinder research engine, electronic dual-fuel injection system, data acquisition system and 5-gas 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. This study investigates the combustion characteristics of ammonia blend fuels (in order to counteract NH3’s unfavorable combustion properties, gasoline has been used as a fuel enhancer). Characterization of emission profiles of species such as HC, O2, H2O, NO2, and CO2 is crucial in understanding combustion with ammonia blend fuels. For every NH3 concentration blend, different exhaust species HC, CO, CO2, O2, and NO2 are measured and compared. CO emissions were found to decrease but emissions of NOx and hydrocarbons were increased with NH3. The tests were performed at variable spark timings and variable engine speeds. The results show that the use of NH3 blend fuels shows comparative results in the brake specific fuel consumption (BSFC), thermal efficiency and combustion efficiency. In addition, the cylinder gas pressure and heat release rate shows promising results; carbon dioxide (CO2) emission increased while hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx) emissions decreased. The results show that NH3 blend can be utilized as an alternative green fuel and energy source.