Search Results (68)

This study creates and tests a machine learning model that can predict fuel use and emissions (NO_x, CO₂, CO, HC, PN) from a marine internal combustion engine when it is running normally. The model learned from data collected from conventional diesel fuel experiments. Subsequently, we evaluated its ability to transfer by employing the parameters associated with waste cooking oil (WCO) biodiesel and its 60/40 diesel mixture. The machine learning model demonstrated exceptional proficiency in forecasting diesel mode (R² > 0.95), effectively encapsulating both long-term trends and short-term fluctuations in fuel consumption and emissions across various load regimes. Upon the incorporation of WCO data, the model maintained its capacity to identify trends; however, it persistently overestimated emissions of CO, HC, and PN. This discrepancy arose primarily from the differing chemical composition of the fuel, particularly in terms of oxygen content and density. A significant correlation existed between indicators of incomplete combustion and the utilization of fuel. Nonetheless, NO_x exhibited an inverse relationship with indicators of combustion efficiency. The findings indicate that the model possesses the capability to estimate emissions in real time, requiring only a modest amount of additional training to operate effectively with alternative fuels. This approach significantly diminishes the necessity for prolonged experimental endeavors, rendering it an invaluable asset for the formulation of fuel strategies and initiatives aimed at mitigating carbon emissions in maritime operations. Full article

Marine transportation contributes approximately 2.5% of global greenhouse gas emissions. While previous studies have examined biodiesel effects on automotive engines, research on marine applications reveals critical gaps: (1) existing studies focus on single-parameter analysis without considering the complex interactions between biodiesel ratio, engine load, and operating conditions; (2) most research lacks comprehensive lifecycle assessment integration with real-time operational data; (3) previous optimization models demonstrate insufficient accuracy (R² < 0.80) for practical marine applications; and (4) no adaptive algorithms exist for dynamic biodiesel ratio adjustment based on operational conditions. These limitations prevent effective biodiesel implementation in maritime operations, necessitating an integrated multi-parameter optimization approach. This study addresses this research gap by proposing an integrated optimization model for fuel efficiency and emissions of marine diesel engines using biodiesel mixtures under diverse operating conditions. Based on extensive experimental data from two representative marine engines (YANMAR 6HAL2-DTN 200 kW and Niigatta Engineering 6L34HX 2471 kW), this research analyzes correlations between biodiesel blend ratios (pure diesel, 20%, 50%, and 100% biodiesel), engine load conditions (10–100%), and operating temperature with nitrogen oxides, carbon dioxide, and carbon monoxide emissions. Multivariate regression models were developed, allowing prediction of emission levels with high accuracy (R² = 0.89–0.94). The models incorporated multiple parameters, including engine characteristics, fuel properties, and ambient conditions, to provide a comprehensive analytical framework. Life cycle assessment (LCA) results show that the B50 biodiesel ratio achieves optimal environmental efficiency, reducing greenhouse gases by 15% compared to B0 while maintaining stable engine performance across operational profiles. An adaptive optimization algorithm for operating conditions is proposed, providing detailed reference charts for ship operators on ideal biodiesel ratios based on load conditions, ambient temperature, and operational priorities in different maritime zones. The findings demonstrate significant potential for emissions reduction in the maritime sector through strategic biodiesel implementation. Full article

With the implementation of the ISO 8217-2024 marine fuel standard, the use of high-concentration biofuels in ships has become viable. However, relatively few studies have been conducted on the effects of biofuels on cylinder lubrication performance in low-speed, two-stroke marine diesel engines. In this study, catering waste oil was blended with 180 cSt low-sulfur fuel oil (LSFO) to prepare biofuels with volume fractions of 24% (B24) and 50% (B50). These biofuels were evaluated in a MAN marine diesel engine under load conditions of 25%, 50%, 75%, and 90%. The experimental results showed that, at the same engine load, the use of B50 biofuel led to lower kinematic viscosity and oxidation degree of the cylinder residual oil, but higher total base number (TBN), nitration level, PQ index, and concentrations of wear elements (Fe, Cu, Cr, Mo). These results indicate that the wear of the cylinder liner–piston ring interface was more severe when using B50 biofuel than when using B24 biofuel. For the same type of fuel, as the engine load increased, the kinematic viscosity and TBN of the residual oil decreased, while the PQ index and the concentrations of Fe, Cu, Cr, and Mo increased, reflecting the aggravated wear severity. Ferrographic analysis further revealed that ferromagnetic wear particles in the oil mainly consisted of normal wear debris. When using B50 biodiesel, a small amount of fatigue wear particles were detected. These findings offer crucial insights for optimizing biofuel utilization and improving cylinder lubrication systems in marine engines. Full article

This study presents a comprehensive analysis of combustion mechanisms and emission formation in marine diesel engines using biodiesel blends through experimental validation and computational fluid dynamics simulation using Matlab 2024a. Two marine engines were tested—YANMAR 6HAL2-DTN (200 kW, 1200 rpm) and Niigatta Engineering 6L34HX (2471 kW, 600 rpm)—with biodiesel ratios B0, B20, B50, and B100 at loads from 10% to 100%. The methodology combines detailed experimental measurements of exhaust emissions, fuel consumption, and engine performance with three-dimensional CFD simulations employing k-ε RNG turbulence model, Kelvin–Helmholtz–Rayleigh–Taylor droplet breakup model, and extended Zeldovich mechanism for NOx formation modeling. Key findings demonstrate that biodiesel’s oxygen content (10–12% by mass) increases maximum combustion temperature by 25 °C at 50% load, resulting in NOx emissions increase of 5–13% across all loads. Conversely, CO emissions decrease by 7–10% due to enhanced oxidation reactions. CFD analysis reveals that B100 exhibits 12% greater spray penetration depth, 20% larger Sauter Mean Diameter, and 20–25% slower evaporation rate compared to B0. The thermal Zeldovich mechanism dominates NOx formation (>90%), with prompt-NO and fuel-NO contributions increasing from 6.5% and 0.3% for B0 to 7.2% and 1.3% for B100, respectively, at 25% load. Optimal injection timing varies with biodiesel ratio: 13–15° BTDC for B0 reducing to 10–12° BTDC for B100. These quantitative insights enable evidence-based optimization of marine diesel engines for improved environmental performance while maintaining operational efficiency. Full article

The growth of global trade has fueled a booming shipping industry, but high pollutant emissions from low-speed marine diesel engines have become a global concern. In this study, it is hypothesized that the combustion efficiency of biodiesel B10 in low-speed two-stroke diesel engines can be improved and pollutant emissions can be reduced by optimizing the exhaust gas recirculation (EGR) rate and injection time. This study systematically analyzed the effects of EGR rate (5%, 10%, and 20%) and injection time (0 °CA to 6 °CA delay) on combustion and emission characteristics using numerical simulation combined with experimental validation. The results showed that the in-cylinder combustion temperature and NOx emission decreased significantly with the increase in EGR rate, but the soot emission increased. Specifically, NOx emissions decreased by 35.13%, 59.95%, and 85.21% at EGR rates of 5%, 10%, and 15%, respectively, while soot emissions increased by 12.25%, 26.75%, and 58.18%, respectively. Delaying the injection time decreases the in-cylinder pressure and temperature peaks, decreasing NOx emissions but increasing soot emissions. Delaying the injection time from 2 °CA to 4 °CA and 6 °CA decreased NOx emission by 16.01% and 25.44%, while increasing soot emission by 4.98% and 11.64%, respectively. By combining numerical simulation and experimental validation, this study provides theoretical support for the combustion optimization of a low-speed two-stroke diesel engine when using biodiesel, and is of great significance for the green development of the shipping industry. Full article

This study introduces a novel approach to biodiesel production by repurposing starfish, an abundant marine waste, as a sustainable catalyst material. Starfish, primarily composed of Ca-Mg carbonate, were calcined to produce calcium oxide (CaO) and magnesium oxide (MgO), which were subsequently doped with varying zinc loadings through hydrothermal treatment. This innovative use of marine waste not only addresses environmental concerns but also provides a cost-effective catalyst source. Among the tested compositions, the catalyst doped with 10 wt% Zn achieved the highest biodiesel yield of 96.6%, outperforming both lower and higher Zn loadings. Zinc incorporation significantly improved the catalyst’s surface area, pore volume, and active site density, as confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) surface analysis. These enhancements facilitated a biodiesel yield of 96.6% within 10 h, a substantial increase compared to the undoped catalyst (86.5%) under identical conditions. Reusability tests further confirmed the catalyst’s high activity over three consecutive cycles, with yields of 96.6%, 94.2%, and 86.5%, respectively, while SEM-EDS analysis demonstrated effective Zn retention after repeated use. This study demonstrates a pioneering strategy for transforming marine waste into a high-performance catalyst, paving the way for sustainable biodiesel production. Full article

The decarbonization of the operational fleet through the implementation of renewable and low-carbon fuels (LCFs) is considered a key factor in achieving the regulatory greenhouse gas (GHG) reduction targets set by the IMO and the EU. In parallel with optimizing engine energy efficiency and emission characteristics during retrofitting for LCF operations, it is equally important to assess and ensure the reliability of engine components under permissible thermal and mechanical loads. This study investigated the key factors influencing thermal and mechanical stresses on the cylinder–piston assembly components as the engine’s operation shifts from diesel to biodiesel, natural gas, methanol, or ammonia. The methodological foundation of this research was an original comparative analysis method that evaluates the impacts of thermal stress and combustion cycle energy efficiency factors. The combustion cycle energy parameters were modeled using a single-zone mathematical model. The thermal load factor was determined based on the ALPHA (α_gas) coefficient of heat transfer intensity and the average combustion gas temperature (T_avg). The optimization of the combustion cycle during retrofitting was simulated without changes to the engine structure (or without “major” modernization, according to IMO terminology), with modifications limited to the engine’s combustion adjustment parameters. A key characteristic of the transition from diesel to LCFs is a significant increase in the maximum cycle pressure (Pmax), a factor influencing mechanical stresses: ammonia, +43%; LNG, +28%; methanol, +54–70%; biodiesel, no significant changes. This study confirms the adopted strategy to maintain thermal load factors for engine components equal to Dmax conditions. It is emphasized that, after ensuring Pmax-idem conditions, the thermal load during LCF operation aligns closely with the characteristic diesel level with minimal deviation. The thermal load reduction is associated with an increase in the excess air coefficient (λ) and a controlled reduction in the compression ratio within an allowable variation of ±1 unit. Based on statistical correlations, a rational increase in λ was identified, reaching up to 2.5 units. Considering the real-world operational load cycle structure of marine engines, further research will focus on analyzing thermal and mechanical stresses according to ISO 81/78, as well as E2 and E3 operational cycles. Full article

This paper aims to consider the issue of increasing the environmental friendliness of shipping by using alternative fuels in marine diesel engines. It has been determined that marine diesel engines are not only the main heat engines used on ships of sea and inland waterway transport, but are also sources of emissions of toxic components with exhaust gases. The main compounds whose emissions are controlled and regulated by international organizations are sulfur oxides (SO_X) and nitrogen oxides (NO_X), as well as carbon dioxide (CO₂). Reducing NO_X and CO₂ emissions while simultaneously increasing the environmental friendliness of shipping is possible by using fuel mixtures in marine diesel engines that include biodiesel fuel. During the research carried out on Wartsila 6L32 marine diesel engines (Shanghai Wartsila Qiyao Diesel Co. Ltd., Shanghai, China), RMG500 and DMA10 petroleum fuels were used, as well as their mixtures with biodiesel fuel FAME. It was found that when using mixtures containing 10–30% of FAME biodiesel, NO_X emissions are reduced by 11.20–27.10%; under the same conditions, CO₂ emissions are reduced by 5.31–19.47%. The use of alternative fuels in marine diesel engines (one of which is biodiesel and fuel mixtures containing it) is one of the ways to increase the level of environmental sustainability of seagoing vessels and promote ecological shipping. This is of particular relevance when operating vessels in special ecological areas of the World Ocean. The relatively low energy intensity of the method of creating and using such fuel mixtures contributes to the spread of its use on many means of maritime transport. Full article

The FuelEU Maritime Regulation, part of the European Union’s (EU’s) Fit for 55 initiative, aims to achieve significant reductions in greenhouse gas (GHG) emissions within the maritime sector. This study assesses the feasibility of alternative fuels for the Estonian pilot fleet using a Well-to-Wake (WtW) life cycle assessment (LCA) methodology. Operational data from 18 vessels, sourced from the Estonian State Fleet’s records, were analyzed, including technical specifications, fuel consumption patterns, and operational scenarios. The study focused on marine diesel oil (MDO), biomethane, hydrogen, biodiesel, ammonia, and hydrotreated vegetable oil (HVO), each presenting distinct trade-offs. Biomethane achieved a 59% GHG emissions reduction but required a volumetric storage capacity up to 353% higher compared to MDO. Biodiesel reduced GHG emissions by 41.2%, offering moderate compatibility with existing systems while requiring up to 23% larger storage volumes. HVO demonstrated a 43.6% emissions reduction with seamless integration into existing marine engines. Ammonia showed strong potential for long-term decarbonization, but its adoption is hindered by low energy density and complex storage requirements. This research underscores the importance of a holistic evaluation of alternative fuels, taking into account technical, economic, and environmental factors specific to regional and operational contexts. The findings offer a quantitative basis for policymakers and maritime stakeholders to develop effective decarbonization strategies for the Baltic Sea region. Full article

With increasingly strict emission regulations, research on diesel engine combustion and emissions is urgently needed. This study conducted computational fluid dynamics modeling on diesel engines. The effects of intake humidity and oxygen concentration of a diesel engine on the combustion emission of biodiesel were studied. The results indicate that when the humidity ratio is below 0.4 (WR = 0.4), intake humidification has a certain promoting effect on the combustion reaction process. Water molecule pyrolysis can promote the pyrolysis of biodiesel, and the peak pressure in the cylinder slightly increases. As the intake humidification ratio increases, the cylinder temperature decreases, and the oxygen concentration also decreases due to the increase in water molecular weight. The combustion reaction process is suppressed, and the cylinder pressure decreases. When the humidity ratio is 1 (WR = 1), the peak pressure decreases by 2.61% compared to when it is not humidified (WR = 0). The concentration of O radicals decreases with an increase in humidity ratio. When WR = 1.0, the emissions of NO_x decreased by 55.02%, but with the decrease in oxygen concentration in the high-temperature area, the emissions of soot increased. The results indicate that as the oxygen concentration increases, the cylinder pressure and average temperature increase, the ignition-delay time decreases, the heat-release rate increases, and it ultimately leads to an increase in NO_x emissions. Full article

The sustainable utilization of co-products derived from the salmon processing industry is crucial for enhancing the viability and decreasing the environmental footprint of both capture and aquaculture operations. Salmon (Salmo salar) is one of the most consumed fish worldwide and a major species produced in aquaculture. As such, significant quantities of salmon co-products are produced in pre-commercialization processing/steaking procedures. The present study characterized a specific co-product derived from the processing of salmon: minced salmon heads. More specifically, this work aimed to reveal the nutritional profile of this co-product, with a special focus on its lipid content, including thoroughly profiling fatty acids and fully appraising the composition in complex lipids (polar lipids and triglycerides) for the first time. The antioxidant potential of lipid extracts from this salmon co-product was also studied in order to bioprospect lipid functional properties and possibly unveil new pathways for added-value applications. Our analysis indicated that these minced salmon heads are exceptionally rich in lipids. Oleic acid is the most prevalent fatty acid in this co-product, followed by palmitic acid, stearic acid, and linoleic acid. Moreover, relevant lipid indexes inferred from the fatty acid composition of this co-product revealed good nutritional traits. Lipidome analysis revealed that triglycerides were clearly the predominant lipid class present in this co-product while phospholipids, as well as ceramides, were also present, although in minimal quantities. The bioprospecting of antioxidant activity in the lipid extracts of the minced salmon heads revealed limited results. Given the high concentration of triglycerides, minced salmon heads can constitute a valuable resource for industrial applications from the production of fish oil to biodiesel (as triglycerides can be easily converted into fatty acid methyl esters), as well as possible ingredients for cosmetics, capitalizing on their alluring emollient properties. Overall, the valorization of minced salmon heads, major co-products derived from the processing of one of the most intensively farmed fish in the world, not only offers economic benefits but also contributes to the sustainability of the salmon processing industry by reducing waste and promoting a more efficient use of marine bioresources. Full article

This study addresses the need to implement sustainable alternatives in marine vessels, particularly in vulnerable environments, highlighting the potential of biofuels as a viable option for the transition towards renewable energy. The objective of the research was to evaluate the interest and perception of tourism service providers in Los Cabos, B.C.S., Mexico, regarding the alternative use of biofuels in their vessels. A total of 56 random surveys were applied and validated, and the results were as follows: 92% consider fuel to be their largest operational cost, 84.6% acknowledge that their activities impact the environment, and 80% are aware of biodiesel biofuel. Notably, more than 94% expressed interest in learning how to produce biodiesel and in using it as an alternative in their operations, while 95% believe that the use of biofuels could be a positive differentiating feature for their businesses, contributing to an eco-friendlier service. This introductory assessment is crucial as it highlights the importance of understanding the willingness of key stakeholders before adopting new technologies. It concludes that there is strong interest in exploring and adopting sustainable alternatives, reinforcing the need for further research to provide viable solutions, promoting a circular economy and fostering sustainable tourism in alignment with the Sustainable Development Goals. Full article

This article considers the issues of ensuring operational performance and environmental sustainability of marine diesel engines by using biodiesel fuel. This research was conducted on 5S60ME-C8 MAN-B&W Diesel Group and 6DL-16 Daihatsu Diesel marine diesel engines, which are operated using RMG380 petroleum fuel and B10 and B30 biodiesel fuels. The efficiency of biofuel usage was assessed based on environmental (reduced nitrogen oxide concentration in exhaust gases) and economic (increased specific effective fuel consumption) criteria. It was found that the use of B10 and B30 biofuels provides a reduction in nitrogen oxide concentration in exhaust gases by 14.71–25.13% but at the same time increases specific effective fuel consumption by 1.55–6.01%. Optimum fuel injection advance angles were determined that ensure the best thermal energy, economic and environmental performance of diesel engines. The optimum angle of biofuel supply advance is determined experimentally and should correspond to the limits recommended by the diesel engine operating instructions. It has been proven experimentally that the use of biofuel increases the environmental sustainability of marine diesel engines by 13.75–29.42%. It increases the diesel engines environmental safety in case of emergency situations as well as accidental and short-term emissions of exhaust gases with an increased content of nitrogen oxides into the atmosphere phenomena that are possible in starting modes of diesel engine operation as well as in modes of sudden load changes. It is the increase in the environmental friendliness of marine diesel engines in the case of using biofuel that is the most positive criterion and contributes to the intensity of biofuel use in power plants of sea vessels. Full article

The conventional utilization of fossil fuels precipitates uncontrolled carbon dioxide and sulfur oxides emissions, thereby engendering pronounced atmospheric pollution and global health ramifications. Within the maritime domain, concerted global initiatives aspire to mitigate emissions by 2050, centering on the adaptation of engines, alteration of fuel compositions, and amelioration of exhaust gas treatment protocols. This investigation pioneers experimentation with marine gas oil augmented by methanol, a practice conventionally encumbered by prohibitively expensive additives. Successful amalgamation of methanol, animal-derived biodiesel, and marine gas oil (MGO) is empirically demonstrated under meticulously controlled thermal conditions, creating a homogeneous blend with virtually zero sulfur content and reduced carbon content, featuring characteristics akin to conventional marine gas oil but with no use of expensive emulsifiers. This new blend is suitable for employment in maritime engines utilizing Delaval technology, yet with significantly lower energy requirements compared to those necessitated using conventional very low sulfur fuel oil (VLSFO) with a maximum sulfur content of 0.5% w/w. Full article

Solving strategic IMO tasks for the decarbonization of maritime transport and the dynamics of its controlling indicators (EEDI, EEXI, CII) involves the comprehensive use of renewable and low-carbon fuels (LNG, biodiesel, methanol in the mid-term perspective of 2030, ammonia, and hydrogen to achieve zero emissions by 2050) and energy-saving technologies. The technology of regenerating secondary heat sources of the ship’s power plant WHR in the form of an Organic Rankine Cycle (ORC) is considered one of the most promising solutions. The attractiveness of the ORC is justified by the share of the energy potential of WHR at 45–50%, almost half of which are low-temperature WHR (80–90 °C and below). However, according to DNV GL, the widespread adoption of WHR-ORC technologies, especially on operating ships, is hindered by the statistical lack of system prototypes combined with the high cost of implementation. Developing methodological tools for justifying the energy efficiency indicators of WHR–ORC cycle implementation is relevant at all stages of design. The methodological solutions proposed in this article are focused on the initial stages of comparative evaluation of alternative structural solutions (without the need to use detailed technical data of the ship’s systems, power plant, and ORC nodes), expected indicators of energy efficiency, and cycle performance. The development is based on generalized results of variation studies of the ORC in the structure of the widely used main marine medium-speed diesel engine Wärtsilä 12V46F (14,400 kW, 500 min⁻¹) in the operational load cycle range of 25–100% of nominal power. The algorithm of the proposed solutions is based on the established interrelationship of the components of the ORC energy balance in the P-h diagram field of thermodynamic indicators of the cycle working fluid (R134a was used). The implemented strategy does allow, in graphical form, for justifying the choice of working fluid and evaluating the energy performance and efficiency of alternative WHR sources for the main engine, taking into account the design solutions of the power turbine and the technological constraints of the ORC condensation system. The verification of the developed methodological solutions is served by the results of comprehensive variation studies of the ORC performed by the authors using the professionally oriented thermoengineering tool “Thermoflow” and the specification data of Wärtsilä 12V46F with an achieved increase in energy efficiency indicators by 21.4–7%. Full article