Search Results (1,990)

With the increasingly prominent environmental and energy issues, emission regulations are becoming more stringent. Ammonia diesel dual fuel (ADDF) engine is one of the effective ways to reduce carbon emissions. This study investigated the effect of multiple injection strategy on the combustion and emission characteristics of liquid ammonia/diesel dual direct injection (DI) engines through numerical simulation. The results showed that under the condition of maintaining the same pre injection diesel fuel and high ammonia energy ratio (80%), with the introduction of multiple injection, the peak cylinder pressure decreased and the peak phase advanced, the combustion start angle (CA10) advanced, the heat release showed a multi-stage pattern. The times of injection (TSOI) has a significant effect on combustion and emissions. As TSOI increased, ignition delay decreased, the combustion duration is shortened, and the combustion is accelerated. Notably, overall emissions of NOx and N₂O have decreased, but the emissions of unburned NH₃ have increased. Optimized the state of ammonia injection (SOAI) timing and ammonia injection pressure (AIP), showed that advancing SOAI timing and increasing AIP improved combustion. Advanced the SOAI timing to −8 °CA ATDC, resulted in a significant NOx emissions decrease with an increase in TSOI, reaching over 50%. Although increasing injection pressure can improve combustion, it also results in higher N₂O emissions. Full article

The growing demand for chicken meat products has increased the amount of wastewater associated with their production; their treatment has increased the generation of sludge and oils trapped in the trap process treatment. This work presents a process for the valorization of this residual oil recovered through the production of biodiesel. An oil degumming process was applied, and the quality of the treated oil was evaluated. This was transesterified with alkaline conditions and a homogeneous catalyst (KOH); a 3^k experimental design was applied with two factors: the temperature at 50, 60, and 70 °C and the molar ratios of 5, 6, and 7 moles of methanol per mole of recovered chicken oil. The biodiesel quality parameters were evaluated based on the ASTM standard. The process achieved a yield of 90.2%. The biodiesel obtained met all the quality parameters; however, only the process conditions with a molar ratio of 6:1 and a temperature of 60 °C achieved a kinematic viscosity of 5.64 ± 0.15 mm² s⁻¹, meeting the limits of 1.9–6.0 mm² s⁻¹ of the ASTM regulation. The fluidity of this biodiesel in mixtures of 25, 50, and 75% v with petroleum diesel was also evaluated, and a better adjustment of the Bingham mixing rule model and rheological analysis revealed that the mixtures did not lose their Newtonian behavior. This allows for the application of this biodiesel in internal combustion engines, achieving the valorization of residual oil. Full article

Two engine oil additives with graphene were tested in diesel engines. The first was a graphene oxide (GO)-based, commercially available additive that the supplier recommends using at a 3% v/v concentration in engine oil. The second was a graphene nanoplatelet (GNP)-based additive that is under development, which is more concentrated and allows for the addition of a much smaller amount of additive. Using the GO additive results in a reduction of brake-specific fuel consumption from 0.2% to 0.7%, depending on the engine load, and a 2% reduction in fuel consumption when the engine is run without load. The use of 0.1% wt of GNPs led to 0.4% of fuel savings on an ESC emission cycle. Increasing the GNP concentration to 0.2% did not further reduce fuel consumption. Full article

Ni₃Sn₄ intermetallic compound (IMC) is a critical material in modern electronic packaging and soldering technology. Although Ni₃Sn₄ enhances the strength of solder joints, its brittleness and anisotropy make it prone to crack formation under mechanical stress, such as thermal cycling or vibration. To improve the plasticity of Ni₃Sn₄ and mitigate its anisotropy, this study employs first-principles calculations to investigate the mechanical properties and electronic structure of the doped compounds Ce_x Ni_3−xSn₄ (x = 0, 0.5, 1, 1.5, 2) by adding the rare earth element Ce. The results indicate that the structure Ce_0.5 Ni_2.5Sn₄ has a lower formation enthalpy (${\mathrm{H}}_{\mathrm{f}}$) compared to other doped structures, suggesting enhanced stability. It was found that all structures exhibit improved plasticity with Ce doping, while the Ce_0.5 Ni_2.5Sn₄ structure shows relatively minor changes in hardness (H) and elastic modulus, along with the lowest anisotropy value (${\mathrm{A}}^{\mathrm{U}}$). Analysis of the total density of states (TDOS) and partial density of states (PDOS) reveals that the electronic properties are primarily influenced by the Ni-d and Ce-f orbitals. At the Fermi level, all Ce_x Ni_3−xSn₄ (x = 0, 0.5, 1, 1.5, 2) structures exhibit metallic characteristics and distinct electrical conductivity. Notably, the TDOS value at the Fermi level for Ce_0.5 Ni_2.5Sn₄ lies between those of Ni₃Sn₄ and other doped structures, indicating good metallicity and conductivity, as well as relative stability. Further PDOS analysis suggests that Ce doping enhances the plasticity of Ni₃Sn₄. This study provides valuable insights for the further application of rare earth elements in electronic packaging materials. Full article

To mitigate the effects of climate change, novel carbon capture technologies need to be developed. Since 2020, a new solution has been to adopt an energy-efficient combination of “amine blend + heterogeneous catalysts” in large CCUS demonstration plants. This study adopted the specific tri-solvent MEA-EAE-AMP and solid catalysts CaSO₄, HND-580, and HND-8 in a novel bench-scale pilot plant with hot oil as the heat source. Three key parameters were investigated—absorption efficiency (AE), cyclic capacity (CC), and heat duty (HD)—to analyze the technology under a steady state. The results indicated that the solid acid significantly reduced α_lean and the solid base increased αrich, while the CC was increased and HD was reduced to its minimum at 2.47 GJ/tCO₂ and at optimized doses of the catalysts, 40 g CaSO₄ and 100 HND-580. These results verified another energy-efficient solution that could be further scaled up into an industrial amine scrubbing pilot plant. Full article

Agriculture may hold the key to a sustainable future. By efficiently capturing atmospheric CO₂, we can simultaneously produce food, feed, biomass, and biofuels. For more eco-friendly soil processing practices, biofuels can replace diesel in agricultural machinery, significantly reducing the carbon footprint of crop production. Thus, biofuel production can be a sustainable solution for a future with a decreasing carbon footprint. This paper examines the possibility of replacing petroleum-based fuels with 100% biofuels to continue powering heavy-duty vehicles, where the use of electric vehicles is not the optimal solution. This study particularly focused on the operating scenario of heavy-duty engines under medium to high loads, typical of transport or soil processing in agriculture. Diesel was used as a benchmark, and each alternative, such as vegetable oil, methyl ester (B100), and methyl ester–ethanol blends (90B10E, 80B20E, and 70B30E), was tested individually. To find a sustainable fuel substitute, the goal was to identify a biofuel with a kinematic viscosity similar to that of diesel for a comparable spray process. Experimental results showed that an 80% methyl ester and 20% ethanol blend had a kinematic viscosity close to that of diesel. In addition to diesel, this blend resulted in a 48.6% reduction in exhaust gas opacity and a 6.54% lower specific fuel consumption (BSEC). The main aim of the tests was to find a 100% biofuel substitute without modifying the fuel injection systems of existing engines. Full article

Marine two-stroke dual-fuel (DF) engines with a low-pressure gas concept normally face the problem of inferior fuel economy in diesel mode, mainly due to their lower compression ratio. To address this issue, a numerical study is performed to investigate the applicability of variable compression ratio (VCR) in a marine two-stroke DF engine, aiming at improving fuel economy in diesel mode. First, an engine simulation model is established and validated. Then, parametric investigation is performed to obtain insights on the effects of VCR on engine combustion, performance, and emissions. Finally, regression models of selected engine response variables are determined based on the response surface methodology (RSM), which are then optimized by particle swarm optimization (PSO) to obtain the optimal solution of engine setting parameters. The results show that with the application of VCR, the brake specific fuel consumption (BSFC) decreases by 9.65, 11.38, 11.13, and 11.27% at 25, 50, 75, and 100% maximum continuous rating (MCR), respectively. Meanwhile, the nitrogen oxides (NOx) emissions are maintained at the original levels, and the engine’s operating parameters are within specified limits. This study contributes to the delineation of the benefits and limits of VCR and provides a feasible method to facilitate the implementation of VCR in marine engines. Full article

Ammonia, being 17.6% hydrogen by mass, is regarded as a hydrogen carrier and carbon-free fuel as long as its production methods rely on renewable energy sources. The production and combustion of green ammonia do not generate carbon dioxide, offering a promising avenue for substantial reductions in greenhouse gas (GHG) emissions from a well-to-wake perspective. This paper presents a comprehensive methodology for the development and validation of a thermodynamic model for a two-stroke low-speed marine engine incorporating a hybrid ammonia-diesel diffusion combustion system. The simulation tools are rigorously validated using experimental data obtained during diesel operation. Subsequently, the study explores various aspects of the novel ammonia-diesel combustion system, addressing combustion and emissions characteristics. The investigation incorporates diverse simulation scenarios involving direct fuel injection through dedicated valves into the cylinder head of a six-cylinder, turbocharged compression-ignition engine. The engine features two diesel injection valves, employed to initiate the combustion process, and two ammonia injection valves. Simulation scenarios include variations in the injection timing of the pilot diesel injector and the relative orientation of diesel and ammonia sprays. Case C emerges as the preferred configuration, demonstrating superior metrics in terms of combustion stability, air-fuel mixing, and emissions profile compared to other cases. The results indicate a reduction of CO₂ emissions of approximately 95% in mass compared to the baseline diesel operation. Furthermore, notable reductions in NO_x emissions are observed, preliminarily attributed to the lower flame temperature of ammonia. Despite the appearance of N₂O emissions as a result of ammonia oxidation, the overall potential reduction in GHG emissions, in CO₂-equivalent terms, exceeds 85% at selected operating points. This work contributes valuable insights into the optimization of cleaner propulsion systems for maritime applications, facilitating the industry’s transition toward more sustainable and environmentally friendly practices. Full article

2-Methylfuran (2-MF) has emerged as a promising renewable alternative fuel, primarily due to its sustainable production processes and its potential to significantly reduce soot emissions. However, when blended with diesel, it presents challenges, including an increase in NOx emissions, which is attributed to the lower cetane number (CN) of the M30 blend. This study investigates the effect of adding 2-ethylhexyl nitrate (2-EHN), a cetane enhancer, to the M30 blend (30% 2-MF by volume), on combustion characteristics and exhaust emissions. Experiments were conducted using a modified four-cylinder, four-stroke, direct-injection compression ignition (DICI) engine featuring a common rail fuel injection system. The engine was evaluated under different load conditions, with brake mean effective pressure (BMEP) ranging from 0.13 to 1.13 MPa, while maintaining a constant engine speed of 1800 rpm. The incorporation of 1.5% and 2.5% 2-EHN into the M30 blend enhanced combustion performance, as indicated by a reduction in the maximum pressure rise rate, a shorter ignition delay (ID), and an extended combustion duration (CD). Furthermore, the brake-specific fuel consumption (BSFC) reduced by 2.78% and 5.7%, while the brake thermal efficiency (BTE) increased by 3.54% and 7.1%, respectively. Moreover, the inclusion of 2-EHN led to a significant reduction in Nox by 9.20–17.57%, with the most significant reduction observed at a 2.5% 2-EHN, where hydrocarbon (HC) decreased by 7.93–21.59%, and carbon monoxide (CO) reduced by 12.11–33.98% as compared to the M30 blend without 2-EHN. Although a slight increase in soot emissions was observed with higher concentrations of 2-EHN, soot levels remained significantly lower than those from pure diesel. The results indicate that the addition of 2-EHN can effectively mitigate the trade-off between NOx and soot emissions in low cetane number oxygenated fuels. Full article

With the development of China’s social economy and urbanization, there is a significant stock of urban industrial architectural heritage. Considering the increasing demand for urban land and the renewal of idle sites, the reuse of industrial architectural heritage has become an important measure for urban development, while preserving the city’s industrial memory and the authenticity of architectural heritage. This paper conducts a reuse study on the industrial architectural heritage in Hefei based on human thermal comfort. The motor factory welding workshop and the diesel engine factory cylinder casting workshop in Hefei are selected as research objects. By measuring the physical parameters of the indoor thermal environment and the thermal comfort of human bodies before and after the renovation of these two workshops and by conducting data statistics and regression analyses on the measured data and questionnaire data, an actual mean thermal sensation MTS model of human thermal comfort in the indoor space of the industrial architectural heritage before and after reuse is established. This paper compares the neutral temperature, comfortable temperature range, and duration of thermal comfort at different times for the research objects; analyzes the reasons for the differences in the results; and draws conclusions from the comparative analysis, providing a theoretical basis for the practice of comfortable environment transformation of industrial architectural heritage. Full article

Diesel engines employed in non-road machinery are significant contributors to nanoparticulate matters. This paper presents a novel device based on the principle of split-stream rushing to mitigate particulate matter emissions from these engines. By organizing and intensifying the airflow movement of the jet in the rushing region, the probability of collisions between nanoparticles is enhanced. This accelerates the growth and coagulation of nanoparticles, reducing the number density of fine particulate matter. This, in turn, facilitates the capture or sedimentation of particulate matter in the diesel engine exhaust aftertreatment system. The coagulation kernel function tailored for diesel engine exhaust nanoparticles is developed. Then, the particle balance equation is solved to investigate the evolution and coagulation characteristics. Afterwards, three-dimensional numerical simulations are performed to study the flow field characteristics of the split-stream rushing device and the particle evolution within it. The results show that the device achieves a maximum coagulation efficiency of 59.73%, increasing the average particle diameter from 96 nm to 121 nm. The particle number density uniformity index exceeded 0.93 in most flow regions, highlighting the effectiveness of the device in ensuring consistent particle distribution. Full article

As modern marine diesel engine systems become increasingly complex, effective condition monitoring methods are essential for ensuring optimal performance and preventing anomalies. This paper proposes a data-driven condition monitoring approach specifically designed for the lubrication system of marine diesel engines. Unlike traditional methods, the proposed approach eliminates the need for explicit modeling and leverages a novel optimization algorithm for data denoising. Additionally, a new noise-resistant monitoring index is introduced to enhance monitoring reliability. The paper is structured into two main sections for validation. The first section addresses advanced data preprocessing, where the Improved Sparrow Search Algorithm (ISSA) is employed to optimize the parameters of Random Singular Value Decomposition (RSVD). This step effectively minimizes noise, reduces manual intervention, and handles high-dimensional data. The second section focuses on analyzing the data characteristics using the Random Matrix Theory (RMT) and establishing novel condition monitoring indicators to achieve more reliable monitoring outcomes. The proposed methodology captures the intricate relationships among key variables within the system, providing a more robust framework for condition monitoring. Applied to a marine diesel engine lubrication system, the method demonstrates significant improvements in noise immunity and monitoring reliability. Comparative analyses of condition monitoring models before and after denoising reveal that the relative error of the proposed monitoring index under varying noise amplitudes is within 1%, substantially lower than that of other indices. Furthermore, the monitoring accuracy is improved by 4.95% when the proposed index is employed for system condition monitoring. Full article

This study conducts a detailed analysis of the mixed combustion of dissociated methanol gas (DMG) and methanol in a marine medium-speed methanol engine through numerical simulation methods. The research focuses on the impact of partially replacing methanol with DMG on engine combustion characteristics and emissions under both stoichiometric and lean-burn conditions. Employing the MAN L23/30H diesel engine as the experimental model, direct injection of DMG is achieved by installing gas injectors on the cylinder head. Utilizing the CONVERGE software, we simulate the injection and combustion processes of methanol and DMG and subsequently analyze the effects of varying DMG blending ratios on in-cylinder pressure, heat release rate, mean chamber temperature, as well as NOx, HC, CO, and soot emissions. The research findings indicate that, under stoichiometric combustion conditions at both rated and idle speeds, the incorporation of DMG leads to increases in the peak in-cylinder pressure, peak heat release rate, and peak in-cylinder temperature, with these peaks occurring earlier. Additionally, it is observed that emissions of HC, CO, and soot are reduced. Under lean combustion conditions at rated speed, in the absence of DMG blending, increasing the excess air ratio results in an initial increase followed by a decrease in both fuel-indicated and overall-indicated thermal efficiency. However, with the blending of DMG, these efficiencies improve as the excess air ratio increases. Notably, the highest efficiencies are achieved when the excess air ratio is 1.8 and the blending ratio of DMG is 30%. Full article

Predicting end-of-process variables in internal combustion engines, such as brake-specific fuel consumption or pollutant emissions, is crucial for engine design decisions. However, errors in common multi-layer-perceptron-based artificial neural network models often match the magnitude of the expected fuel consumption improvements, potentially leading to incorrect decisions. This study introduces a hybrid model where artificial neural networks replace engine block elements, while the 1D gas circuit and turbocharger models are retained. To enhance metamodel accuracy, two modifications are proposed: incorporating a pulsating mass flow rate in the exhaust line to capture pulsating effects missing in mean-value engine models and using a hierarchical arrangement of several multi-layer perceptrons instead of a parallel arrangement. The pulsating mass flow rate approach improves the accuracy of all tested configurations by replicating pulsating effects from a detailed 1D engine model. Meanwhile, the hierarchical arrangement refines predictions of end-of-process variables, such as fuel consumption, by increasing the total layers, with a minimal trade-off in the accuracy of other variables. These findings are validated using a metamodel derived from a calibrated 1D engine model in GT-Suite. The proposed methods are expected to enhance the accuracy of data-driven artificial neural network approaches, contributing to more reliable engine design optimization. Full article

One of the solutions contributing to the development of energy independence is the utilization of biogas as an alternative fuel for agricultural tractors. Biogas is recognized as a renewable energy source, and its usage aids in the reduction in greenhouse gas emissions on a global scale. The reuse of this material/waste exemplifies the concept of a circular economy. Several models of agricultural tractors designed explicitly for biogas utilization or adaptable for its use are available in the market. This study aimed to evaluate the energy-ecological parameters of the MP tractor (T6.180 Methane Power) powered by Compressed Natural Gas (CNG) in comparison to its structurally identical counterpart fueled by Diesel (T6.180 Electro Command). Based on the Air–Fuel Ratio (AFR) coefficients for diesel and methane, as well as values of air excess ratios (λ) and the proportions of CO and CO₂ emissions determined for various engine load states, the mass emission of selected exhaust components for the examined tractors was estimated. This research highlights that biogas-powered tractors hold the potential to contribute to the sustainable development of agriculture through the reduction in greenhouse gas emissions, improvement in farm energy autonomy, and optimal resource utilization, closely aligned with the principles of a circular economy. Full article