Influence of carbon free gaseous ammonia induction on combustion, performance and emissions in an agricultural diesel engine operated on dual fuel mode

The transition towards cleaner fuels is very important due to its potential to reduce greenhouse emissions and favor the decarbonized engine operation. Recently, Ammonia (NH₃) has emerged as a promising carbon-free energy carrier and alternative fuel, which can replace traditional fossil fuels. This study aims to showcase the procedure of using NH₃ as a primary fuel with 20% Jatropha biodiesel and 80% diesel, designated as JME20 as a pilot fuel in dual-fuel mode. Hence, a single-cylinder DI diesel engine was retrofitted to induct NH₃ into the intake manifold, whereas JME20 is being injected and sprayed into the engine cylinder to initiate the combustion. NH₃ was inducted at different proportions, such as 8, 10, 12, and 16 lpm, which are designated as DFX, DFX1, DFX2, and DFX3, respectively. Experimentation was carried out at different engine loading conditions, such as 0%, 25%, 50%, 75% and 100%. At each load, the corresponding engine characteristics, namely combustion, performance, and emissions, were measured, compared with standard diesel fuel and given in the paper. Results reveal that a maximum of 24.3% NH₃ was replaced for the DFX3 test fuel at full load. Increasing NH₃ share will extend the delay period from 10.9°CA to 12.6°CA for 12 lpm (DFX2); and lengthen the combustion duration (CD) from 43.3°CA to 48.3°CA for the same fuel at full load. Moreover, the peak cylinder pressure increased from 55.4 bar to 58.6 bar, also a 6.7% rise in maximum heat release rate and 4.2% improvement in BTE at 12 lpm. A percentage increase in CO & HC emissions by about 54.3% and 51.8% respectively, than diesel at full load. These findings confirm that 12 lpm (DFX2) is the most balanced and optimum condition, validating NH₃-JME20 as a promising strategy as a sustainable pathway for agricultural engines.