Search Results (9)

Dimethyl ether (DME) is a promising alternative fuel for compression ignition (CI) engines due to its potential to simultaneously reduce nitrogen oxides (NO_x) and particulate matter (PM) emissions while maintaining diesel-equivalent power. However, its combustion behavior under varying injection timing and exhaust gas recirculation (EGR) conditions remains insufficiently characterized for practical calibration. This study investigates the combustion, emissions, and performance of DME relative to diesel using a fully instrumented John Deere 6068CI550 single-cylinder research engine modified for high-pressure common-rail DME operation. Baseline tests were conducted at three ISO 8178 C1 steady-state modes with matched combustion phasing, load, and EGR to isolate fuel property effects. Injection timing and EGR sweeps were then performed at 1600 rpm and 50% load. Results show that DME produces 10–35% lower NO_x and orders-of-magnitude lower PM than diesel while maintaining comparable thermal efficiency. DME exhibits a single-stage premixed heat release structure with reduced peak apparent heat release rates and 4–5° shorter combustion durations than diesel. Stable combustion was sustained up to 55% EGR, beyond which incomplete combustion increased carbon monoxide (CO), total hydrocarbons (THC), and fuel consumption. Optimal low-emission operation occurred near CA50 ≈ 16° ATDC and EGR levels of 30–40%. These findings demonstrate DME’s ability to mitigate the traditional diesel NO_x–PM tradeoff and support its viability as a low-emission CI fuel. Full article

Biodiesel’s application in compression–ignition engines is mostly limited by the type of methyl esters it contains rather than the total amount of feedstocks. In order to modify the fatty acid methyl ester (FAME) profile for better combustion and emissions, cottonseed (CSOME), neem (NOME), and orange peel oil methyl esters (OPOMEs) were carefully mixed. Fuel chemistry was examined using Gas Chromatography–Mass Spectrometry (GC-MS) and Fourier Transform Infrared (FTIR), which confirmed variations in oxygenated functional groups, saturation levels, and volatility. In a single-cylinder CI engine, diesel, single, binary, and ternary biodiesel mixes were tested over 25–100% load at compression ratios of 17 and 18, both with and without 10% EGR. The ester-optimized ternary blend HBO70 delivered the best overall performance at CR 18 with EGR, exhibiting only a 0.61% reduction in BTE while achieving significant reductions in smoke (44%), PM (51%), NO_x (30%), HC (11%), CO (10%), and specific fuel consumption (SFC) (6.8%). Regression analysis confirmed a temperature- and oxygen-controlled NO_x–PM trade-off, demonstrating that ester-profile optimization is an excellent way to achieve cleaner and more efficient CI engine operation. Full article

The selection of a final operating point from a Pareto front set of marine diesel engine configurations relies on the critical task of translating operator priorities into quantitative criterion weights. This study isolates this pivotal weighting step and introduces an operator-defined fuzzy weighting module that maps linguistic importance ratings to normalized weights. This module systematically maps important ratings for Specific Fuel Consumption (SFC), Nitrogen Oxides (NOx), and Particulate Matter (PM) into a set of normalized weights for the Multi-Criteria Decision-Making method. The module’s core is a Mamdani-type fuzzy logic module that utilizes triangular membership functions and centroid defuzzification. These fuzzy weights are integrated with the TriMetric Fusion algorithm to generate a robust consensus ranking. Validation on a Pareto front from a two-stroke diesel engine demonstrates the framework’s efficacy: a Fuel-Economy priority selected a configuration with SFC advantage, while a Strict Environmental Compliance priority correctly identified dual emissions strengths. Furthermore, the system effectively mediated trade-offs in a high-competition scenario. Rank correlation analysis confirmed that while the Pareto front nature of the alternatives leads to inherent similarities in rankings, the fuzzy weights induce significant and logical divergences. Future work will focus on validation with real operator feedback and comparative studies with traditional weighting methods. Full article

Selecting an appropriate Multi-Criteria Decision-Making (MCDM) algorithm for optimizing marine diesel engine operation presents a complex challenge due to the diversity in mathematical formulations, normalization schemes, and trade-off resolutions across methods. This study systematically evaluates fourteen MCDM algorithms, which are grouped into five primary methodological categories: Scoring-Based, Distance-Based, Pairwise Comparison, Outranking, and Hybrid/Intelligent System-Based methods. The goal is to identify the most suitable algorithm for real-time performance optimization of two stroke marine diesel engines. Using Diesel-RK software, calibrated for marine diesel applications, simulations were performed on a variant of the MAN-B&W-S60-MC-C8-8 engine. A refined five-dimensional parameter space was constructed by systematically varying five key control variables: Start of Injection (SOI), Dwell Time, Fuel Mass Fraction, Fuel Rail Pressure, and Exhaust Valve Timing. A subset of 4454 high-potential alternatives was systematically evaluated according to three equally important criteria: Specific Fuel Consumption (SFC), Nitrogen Oxides (NO_x), and Particulate Matter (PM). The MCDM algorithms were evaluated based on ranking consistency and stability. Among them, Proximity Indexed Value (PIV), Integrated Simple Weighted Sum Product (WISP), and TriMetric Fusion (TMF) emerged as the most stable and consistently aligned with the overall consensus. These methods reliably identified optimal engine control strategies with minimal sensitivity to normalization, making them the most suitable candidates for integration into automated marine engine decision-support systems. The results underscore the importance of algorithm selection and provide a rigorous basis for establishing MCDM in emission-constrained maritime environments. This study is the first comprehensive, simulation-based evaluation of fourteen MCDM algorithms applied specifically to the optimization of two stroke marine diesel engines using Diesel-RK software. Full article

In this study, we utilized multi-regional input–output (MRIO) tables from 2012 to 2017 to determine the spatiotemporal characteristics of CO₂ emissions, air pollutant emissions, and value added associated with trade in different regions and industries, as well as the level of coupling coordination among them. Secondly, structural decomposition analysis (SDA) was used to identify the drivers of changes in the above indicators at the regional level. The results show that consumption-based emissions exceeded those based on production in developed regions such as Jing-Jin and the eastern coastal regions, while the opposite occurred in energy hubs such as the northern coastal and central regions; the results of the value added show higher levels in production areas than in consumption areas in the eastern coastal regions, while the opposite trend was observed in the northwestern regions. In different industries, energy production and heavy manufacturing contributed significantly to CO₂, PM_2.5, and SO₂ emissions, while the service industry contributed more to NO_x and VOC emissions and value added. The relationships among the changes in the three consumption-based indicators were divided into four categories: positive synergies, negative synergies, trade-offs A, and trade-offs B. Recommendations for targeted collaborative management strategies were delineated based on a regional resource-driven classification. Full article

Low temperature combustion (LTC) mitigates the nitrogen oxide (NO_x) and particulate matter (PM) trade-off in conventional compression ignition engines. Significant research on LTC using partially premixed charge compression ignition (PPCI) has typically reduced the compression ratio of the engine to control combustion phasing and lower peak temperatures. This study investigates LTC using PPCI with a high-compression-ratio (=21.2) engine by varying fuel injection timing (FIT) from 12.5° to 30.0° before top dead center (BTDC) while modulating EGR (0%, 7%, 14%, and 25%). Advancing FIT led to a gradual rise in the equivalence ratio of the mixture, in-cylinder pressure, temperature, and rate of heat release due to energy losses associated with ignition occurring before the end of the compression stroke. PPCI was successfully achieved with minimal performance impact using a combination of FIT advancements in the presence of high rates of EGR. Specifically, fuel injected at 25.0° BTDC and 25% EGR reduced PM emissions by 59% and total hydrocarbons by 25% compared with conventional FIT (12.5°) without EGR. Moreover, carbon monoxide and NO_x emissions were comparable across set points. As a result, PPCI using high compression ratios is possible and can lead to greater thermal efficiencies while reducing emissions. Full article

n-Octanol, as an oxygenated fuel, is considered as one of the most promising alternative fuels, owing to advantages such as its low hygroscopic nature, high cetane number, and high energy content. However, the introduction of n-octanol leads to a higher viscosity and latent heat of evaporation (LHOE), affecting the combustion and emission performances of compression ignition (CI) engines. This study sheds light on the effect of injection pressures (IPs, ranging from 60 to 160 MPa) on the combustion and emission performances of a turbocharged CI engine, in conjunction with n-octanol/diesel blends. According to the proportion of oxygen content, the test fuels contain pure diesel (N0), N2.5 (2.5% oxygen content in the blending fuels), and N5 (5% oxygen content in the blending fuels). The results indicate that the blending fuels have little influence on the in-cylinder pressure, ignition delay (ID), and CA50, but they improve the brake thermal efficiency (BTE). In terms of emissions, with the use of blending fuels, the levels of carbon monoxide (CO), soot, and nitrogen oxides (NO_X) decrease, whereas emissions of hydrocarbons (HC) slightly increase. With increasing IP, the ID, brake specific fuel consumption (BSFC), HC, CO, and soot decrease significantly, and the BTE and NO_X increase. In addition, the combination of n-octanol and IP improves the trade-off between NO_X and soot and reduces the CO emissions. Full article

This research studies the macroscopic spray structure from a single-hole common rail diesel injector using gasoline-blended 5% biodiesel for use in compression ignition engines. To reduce the NO_X/PM trade-off emissions, researchers are investigating gasoline used in compression ignition engines, called gasoline compression ignition. As a result that gasoline is injected directly into the combustion chamber, its spray field has a significant effect on combustion and emissions. Due to its low lubricity, gasoline is blended with biodiesel 5%, as a lubricity enhancer, to prevent the failure of the high-pressure injection system. The macroscopic spray structures of this gasoline blend were investigated Schlieren photography and planar laser-induced fluorescence-particle image velocimetry. Injection pressure was handled by a conventional common rail system, while ambient pressure was controlled by supplying nitrogen into the constant-volume combustion chamber. The effects of injection pressure and ambient pressure on the gasoline spray elucidated by Planar laser-induced fluorescence coupled with particle-image velocimetry (PLIF-PIV) imagery and comparisons with variations in neat diesel spray. In addition, the flow field of gasoline spray that formed vortexes and vorticity was characterized. The results show that the injection pressure and back pressure had the same effects on the gasoline spray structure, in terms of the penetration tip and cone angle, as on the diesel spray. However, the injection pressure had a greater effect on the diesel spray than the gasoline at low ambient pressure due to the occurrence of cavitation. Moreover, the images show the remarkable turbulent structure of gasoline spray and indicate air entrainment at the spray tip region. Full article

This study has focused on the PM emissions of diesel engines. Diesel engines are attractive power units that are used widely in many fields and have become one of the larger contributors of total petroleum consumption. However, diesel engines are among the main contributors of emissions into the air, especially particulate matter (PM) and nitrogen oxides (NOx). PM is one of the major pollutants emitted by diesel engines and has adverse effects on human health. Accordingly, many studies have been conducted to find alternative fuels that are clean and efficient. Biodiesel, which produces less PM than diesel fuel, is preferred as an alternative source for diesel engines. Therefore, using palm oil methyl ester (POME) for diesel engines would be a more economical and sustainable solution. This study has focused on the PM emissions of diesel engines fuelled by a diesel and POME blend (B5, B10, B20, and B100). A comparison between diesel and the POME blend has been made which involves PM mass concentration and its components (soluble organic fraction (SOF) and dry soot (DS)). Combustion characteristics, such as in-cylinder pressure and rate of heat release of the engine, as well as gaseous emissions, have also been observed at different operating engine loads (0.05 MPa 20%, 0.4 MPa 40%, and 0.7 MPa 60%). The results show that PM emissions of B100 are lower than those of diesel fuel owing to the oxygen content of POME. With regard to the SOF concentration, B100 has a higher SOF value than diesel fuel at all engine loads. Meanwhile, the DS for B100 is lower than that of diesel fuel. Moreover, as the engine load increased, PM and SOF concentrations increased, while DS concentration decreased. The observation of in-cylinder pressure showed that the increment of pressure with the increasing POME blend, as well as the increasing engine load due to the high cetane number for B100, led to a short ignition delay. The engine brake thermal efficiency between the POME blend and mineral diesel was comparable. Furthermore, B100 fuels showed lower engine power at higher brake-specific fuel consumption compared to other tested fuels. In terms of gaseous emissions, increasing POME blends led to an increase in NOx emissions. Meanwhile, as the engine load increased, NOx also continued to increase. The effect of the POME blend on the PM-NOx trade-off observation showed that B100 simultaneously increased the NOx and decreased the PM emissions. It can be concluded that POME creates a lower PM concentration while giving some negative feedback to NOx. Full article