This study experimentally examines the influence of ammonia substitution ratio on the combustion behavior of a dual-fuel diesel engine. In the proposed configuration, ammonia was supplied through the intake manifold, while diesel served as the pilot fuel, directly injected into the combustion chamber. Experiments were conducted under constant engine speed and load conditions, with systematic variations in the ammonia energy fraction. Key combustion parameters, including in-cylinder pressure, heat release rate (HRR), ignition delay (ID), and combustion duration, were analyzed to assess the effects of ammonia concentration. The results reveal that increasing the ammonia fraction leads to an extended ignition delay and slower combustion rates, primarily attributed to the low reactivity of ammonia. Nevertheless, at moderate substitution levels, the heat release pattern becomes smoother, and the peak cylinder pressure remains within an acceptable range. Furthermore, higher ammonia content tends to lower the combustion temperature, potentially contributing to a reduction in NOx emissions. These findings demonstrate that ammonia can be effectively utilized as a partial substitute for diesel fuel when its ratio is carefully optimized. Nevertheless, the results remain constrained by the fixed SOI, constant-load operation, and the absence of boost or EGR, indicating that further optimization and wider operating conditions must be explored in future studies.

The decarbonization of internal combustion engines (ICE) necessitates advanced predictive tools for ammonia, a zero-carbon fuel with complex combustion dynamics. This study develops a deep neural network (DNN) framework to predict performance parameters and emissions in ammonia-fueled spark ignition engines. Experimental data from a V-twin engine and AVL-BOOST simulations were integrated to train a multi-layer DNN architecture. Data partitioning followed a 70%-15%-15% split for training, validation, and testing. The model achieved exceptional accuracy, with training/validation losses converging range from 10–4 to 10–3, MAE below 0.5%, and R2 > 0.99 across all datasets. The DNN captured critical non-linear phenomena: BMEP’s dependence on ignition timing, showing peak performance at optimal phasing, and NOx reduction under advanced ignition due to lowered peak temperatures.

Ammonia (NH3) is a promising carbon-free fuel, but its adoption in spark-ignition engines is hindered by a low laminar flame speed and high ignition energy requirement. This study investigates a multi-coil ignition strategy to overcome these combustion challenges in a direct-injection ammonia engine. Through CFD simulations of a Rapid Compression Expansion Machine (RCEM), the impact of increased spark energy on combustion and emissions was analyzed. The results demonstrate that the multi-coil system transforms the combustion process by generating a larger, more robust initial flame kernel. This is critical for stabilizing the flame and leads to a peak in-cylinder pressure of 5.22 MPa, which is significantly higher than conventional single-coil ignition. Consequently, indicated thermal efficiency and engine power output are substantially improved due to a more complete and accelerated combustion event. However, the higher combustion temperatures responsible for these performance gains also result in a substantial increase in nitrogen oxide (NOx) emissions. The analysis reveals that a 3 ms spark duration offers an optimal balance, minimizing NOx production without compromising combustion quality. This work concludes that a multi-coil ignition system offers a practical and effective pathway for adapting conventional engines to ammonia operation, providing a key engineering solution to the combustion limitations of this zero-carbon fuel.

This study investigated the performance of an advanced oxidation process (AOP) combining hypochlorous acid (HOCl) and ultraviolet (UV) irradiation for the effective abatement of ammonia (NH3) and hydrogen sulfide (H2S), which are both typically emitted from livestock facilities. The removal characteristics were systematically evaluated through a three-phase approach using basic Tedlar bag experiments, controlled chamber tests, and a lab-scale packed-bed scrubber validation. The initial Tedlar bag tests confirmed the superior chemical oxidation capacity of HOCl. It achieved a 10 to 20%p higher NH3 removal efficiency compared to distilled water, including 100% removal at low concentrations. However, the efficiency declined at high concentrations due to the inherent limitations of simple absorption. Subsequent chamber experiments demonstrated that increasing the scrubbing liquid flow rate and incorporating UV irradiation significantly enhanced NH3 removal. This is attributed to improved gas-liquid (G/L) mass transfer and the synergistic effect of radical generation. In the lab-scale scrubber validation, HOCl alone provided a 5 to 10%p improvement over the distilled water baseline. Crucially, the integration of UV resulted in an NH3 removal efficiency exceeding 98% across all tested operating conditions. For H2S, which exhibited a lower initial removal efficiency, performance was enhanced by enlarging the nozzle diameter and increasing the packing height to optimize the scrubber’s physical parameters in combination with high-concentration HOCl and UV application.

Activated carbon has been widely used to control odorous gases due to its high surface area and microporous structure. However, adsorption efficiency for polar ammonia and reactive hydrogen sulfide is limited because of its nonpolar and hydrophobic surface characteristics. In this study, the feasibility of simultaneous removal of ammonia and hydrogen sulfide was evaluated by depositing a Prussian blue analogue (PBA) onto the surface of activated carbon. Palm-based activated carbon and coalbased activated carbon coated with PBA exhibited similar characteristics in ammonia adsorption. When mixed-gas adsorption tests for ammonia and hydrogen sulfide were conducted using PBA-impregnated palm-based activated carbon and ion exchange resin, the activated carbon showed relatively better removal efficiency for both gases than the ion exchange resin. In ammonia adsorption experiments in which the immersion time of K4Fe(CN)6 used in PBA synthesis was varied between 90 and 180 minutes, a slight improvement in adsorption capacity was observed with increasing immersion duration. Since K+ ions can occupy the interstitial sites within the PBA lattice and exchange with NH4 +, the sample with a single K+ post-treatment exhibited an adsorption capacity of 3.18 mg g–1 at 50% breakthrough point. However, additional immersion cycles resulted in decreased adsorption capacity. Under humid conditions, ammonia adsorption performance improved for both PBA-AC and PBA-IER. This enhancement is attributed to the conversion of NH3 into NH4 +, which activates ion-exchange-driven adsorption, as supported by the significantly delayed breakthrough observed for PBA-IER.