To improve the pollutant removal efficiency by non‐thermal plasma (NTP), the effect of H ₂ O vapor and O ₂ on removal efficiency of NO and SO ₂ as well as the reduction of CO was investigated in H ₂ O/O ₂ /SO ₂ /NO/C ₃ H ₆ /CO ₂ /N ₂ system. To analyse the reaction mechanism, the effects of H ₂ O vapor and O ₂ on the emission intensity of and were investigated. The experimental results show that the increase of H ₂ O vapour (0%–9.8%) promotes the generation of OH radicals, increases the removal efficiency of NO from 18.9% to 57.3%, decreases the energy per NO removed from 449.0 to 148.1 eV/NO, increases SO ₂ removal efficiency from 4.8% to 35.3%, decreases the energy per SO ₂ removed decreases from 2784.0 to 582.9 eV/SO ₂ , and reduces the generation of CO from 460 to 229 ppm. In the range of 0%–15%, the increase of O ₂ content promotes the formation of O radicals, increases the removal efficiency of NO from 8.5% to 54.2%, and decreases the energy per NO removed from 994.3 to 156.4 eV/NO. In the range of 0%–5%, increasing O ₂ content promotes SO ₂ removal efficiency from 8.7% to 24.8%, and decreases the energy per SO ₂ removed from 2485.7 to 876.6 eV/SO ₂ . However, CO generation increases from 200 to 350 ppm with the increase of O ₂ in 0%–5% due to the incomplete oxidation of C ₃ H ₆ . In the range of 5%–15%, the increase of O ₂ produces more O radicals, decreases the removal efficiency of SO ₂ from 24.8% to 23.5% and the generates of CO from 350 to 311 ppm. This study is helpful for improving the efficiency of NTP for desulfurization and denitrification, while reducing the by‐product CO.

To address the issues of the high cost of marine turbocharger fault simulation testing and the difficulties in obtaining fault sample data, a multi-body dynamics model of a marine turbocharger was developed. The simulation approach was used to acquire the turbocharger vibration signals. The result shows that the amplitude of the 1× vibration signal power spectrum drops as the bearing surface roughness increases. However, the amplitude of the 2× and 9× vibration signal power spectra increases as the roughness increases. The TrAdaBoost transfer learning method is used to develop a marine turbocharger diagnosis model. The validation results of 2040 simulated fault samples reveal that when the desired sample number is 20, the diagnostic model has an accuracy of 87%. When the desired number of samples is 40, the diagnostic model’s accuracy is 96%. The diagnosis model may perform diagnosis information transfer between the actual turbocharger and the simulation model.

To improve NO oxidation and energy efficiency, the effect of dielectric barrier discharge reactor structure on NO oxidation was studied experimentally in simulated diesel exhaust at atmospheric pressure. The mixture of 15% O₂/N₂ (balance)/860 ppm NO_X (92% NO + 8% NO₂) was used as simulated diesel exhaust. The results show that DBD reactor with 100-mm electrode length has the highest oxidation degree of NO_X and energy efficiency. NO oxidation efficiency is promoted and the generation of NO is inhibited significantly by increasing the inner electrode diameter. Increasing the inner electrode diameter not only improve the E/N, but also makes the distribution of E/N more concentrated in the gas gap. The secondary electron emission coefficient (γ) of electrode material is closely related to electron energy and cannot be considered as a constant, which causes the different performance of electrode material for NO oxidation under different gas gap conditions. Compared with the rod electrode, the screw electrode has a higher electric field strength near the top of the screw, which promotes the generation of N radicals and inhibits the generation of O radicals. Rod electrode has a higher NO oxidation and energy efficiency than screw electrode under oxygen-enriched condition.

Compared to diesel, liquefied natural gas (LNG), often used as an alternative fuel for marine engines, comes with significant advantages in reducing emissions of particulate matter (PM), SO_x, CO₂, and other pollutants. Promoting the use of LNG is of great significance for achieving carbon peaking and neutrality worldwide, as well as improving the energy structure. However, compared to diesel engines, medium- and high-speed marine LNG engines may produce higher methane (CH₄) emissions and also have nitrogen oxide (NO_x) emission issues. For the removal of CH₄ and NO_x from the exhaust of marine LNG engines, the traditional technical route of combining a methane oxidation catalyst (MOC) and an HN₃ selective catalytic reduction system (NH₃-SCR) will face problems, such as low conversion efficiency and high operation cost. In view of this, the technology of non-thermal plasma (NTP) combined with CH₄-SCR is proposed. However, the synergistic mechanism between NTP and catalysts is still unclear, which limits the optimization of an NTP-CH₄-SCR system. This article summarizes the synergistic mechanism of NTP and catalysts in the integrated treatment process of CH₄ and NO_x, including experimental analysis and numerical simulation. And the relevant impact parameters (such as electrode diameter, electrode shape, electrode material, and barrier material, etc.) of NTP reactor energy optimization are discussed. The work of this paper is of great significance for guiding the high-efficiency removal of CH₄ and NO_x for an NTP-CH₄-SCR system.

The inner electrode diameter on performances of dielectric barrier discharge reactor for desulfurization and denitrification was systematically investigated in H ₂ O/O ₂ /SO ₂ /NO/ C ₃ H ₆ /CO ₂ /N ₂ system. For analysis of the mechanism, the emission intensity of O(3p ⁵ P → 3s ⁵ S ₂ ⁰ ) and OH(A ² Σ ⁺ → X ² Π) , gas temperature, and reduced field strength (E/N) were measured by optical emission spectra (OES). The experimental results show that increasing of inner electrode diameter can improve the oxidation degree of NOx and reduce energy consumption. For SO ₂ removal, the SO ₂ concentration at the outlet of the dielectric barrier discharge (DBD) reactor decreases linearly with the increase of specific energy density (SED) for different inner electrode diameter, and inner electrode diameter has little effect on SO ₂ removal. Increasing SED can increase the emission intensity of OH and O radicals, which makes more SO ₂ been oxidized to SO ₃ and H ₂ SO ₄ by O and OH. The DBD reactor with a bigger inner electrode diameter has a lower gas gap temperature and higher E/N under the same SED, which effectively improves the electron energy, increases the formation of oxidative radicals, and reduces energy consumption.

With the continuous growth of international maritime trade, black carbon (BC) emissions from ships have caused great harm to the natural environment and human health. Controlling the BC emissions from ships is of positive significance for Earth’s environmental governance. In order to accelerate the development process of ship BC emission control technologies, this paper proposes a BC emission prediction model based on stacked generalization (SG). The meta learner of the prediction model is Ridge Regression (RR), and the base learner combines four models: Extreme Gradient Boosting (XGB), Light Gradient Boosting Machine (LGB), Random Forest (RF), and Support Vector Regression (SVR). We used mutual information (MI) to measure the correlation between combustion characteristic parameters (CCPs) and BC emission concentration, and selected them as the features of the prediction model. The results show that the CCPs have a strong correlation with the BC emission concentration of the diesel engine under different working conditions, which can be used to describe the influence of the changes to the combustion process in the cylinder on the BC generation. The introduction of the stacked generalization method reconciles the inherent bias of various models. Compared with traditional models, the fusion model has achieved higher prediction accuracy on the same datasets. The research results of this paper can provide a reference for the research and development of ship black carbon emission control technologies and the formulation of relevant regulations.