An international team from the Middle East has investigated the characteristics of diesel engines powered by petroleum diesel fuel blended with different volumetric percentages of aqueous ammonia. A paper on their findings—including useful literature background on combustion of diesel/gasoline and ammonia—is published in the journal Fuel.
The researchers used Diesel-RK modeling and simulation software—developed at Bauman Moscow State Technical University—in their analysis of three volumetric blends of ammonia along with diesel: 40% NH4OH + 60% Diesel; 50% NH4OH + 50% diesel; and 60% NH4OH + 40% diesel. The numerical analysis is based on a multizone combustion model. In the zone-based approach, the governing equations for each zone are solved as open systems.
In the simulations, the team used a constant engine speed of 1500 RPM, an injection pressure of 160 bar, and 20° BTDC injection timing. The compression ratio was kept constant at 15.5.
The results show that adding ammonia solutions decreases combustion pressure and heat release and increases Sauter mean diameter (a representation of the mean diameter of a collection of particles) and ignition delay.
The researchers found that generally the use of aqueous ammonia drops engine performance regardless of the percentage of NH4OH used. Since 40%, 50%, and 60% of NH4OH have lower heating values than diesel, BSFC is reduced by 7.15, 10.4%, and 15.38%, respectively.
Because the addition of ammonia reduces combustion temperature significantly, a noticeable reduction in NOx emissions was achieved, reaching up to 61.75% in the case of 60% NH4OH. The results highlighted a reduction in soot emissions (43.4% for 40% NH4OH, 51.04% for 50% NH4OH, and 49% for 60% NH4OH) because the diesel was replaced with a no-carbon fuel, hence the engine produced less smoke compared to with the baseline case (pure diesel).
Mohamed F. Al-Dawody, Wisam Al-Obaidi, Emad D. Aboud, Mohammed A. Abdulwahid, Khaled Al-Farhany, Wasim Jamshed, Mohamed R. Eid, Zehba Raizah, Amjad Iqbal (2023) “Mechanical engineering advantages of a dual fuel diesel engine powered by diesel and aqueous ammonia blends,” Fuel, Volume 346, doi: 10.1016/j.fuel.2023.128398