Abstract
This study investigates and evaluates systematically the combustion,
performance, and emissions characteristics of heavy-duty diesel engines
fueled by diesel–ammonia–compressed natural gas triple blends. While
dual-fuel systems are well-documented, the interactive effects of ammonia
and CNG within a single compression ignition (CI) engine remain largely
unexplored. Experiments were conducted on a 300 Nm, 660 rpm diesel engine by
testing pure diesel, diesel–ammonia blends (10–20 wt.% aqueous ammonia), and
triple-fuel mixtures containing 10% of the total energy from compressed
natural gas. Pure diesel was first tested to provide baseline data, and
subsequently blends were tested for a comparative study. The primary
contribution of this work is the identification of a synergistic effect of
the fuel triple blends on engine performance and emissions.
Results indicate that all fuel blends improve thermal efficiency and reduce
fuel consumption compared to conventional diesel. The blend containing 20%
aqueous ammonia, 80% diesel, and 10% of the total fuel energy supplied by
compressed natural gas achieved the highest thermal efficiency of 39.7% (7%
higher than diesel) and the lowest brake specific fuel consumption of 211.22
g/kWh. Furthermore, emissions analysis revealed that carbon dioxide and
nitrogen oxide emissions were significantly reduced with this triple blend.
The blend decreased carbon dioxide by 26.6% and nitrogen oxide emissions by
32.1%, while hydrocarbon emissions were also lowered by up to 29.2%. Carbon
monoxide emissions increased slightly for the triple blends, reaching a
maximum value of 3.9028 g/kWh for the A20D80CNG10 mixture, compared to
diesel operation. The slight increase in carbon monoxide emissions for
triple blends highlights a trade-off in emission behavior.
These findings address the combined utilization of diesel–ammonia–compressed
natural gas triple-fuel mixtures in heavy-duty engines, demonstrating that
strategic blending can simultaneously improve efficiency while mitigating
environmental impact.
