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With the tightening of emission regulations for marine engines, it has become increasingly important to explore efficient and clean combustion strategies in diesel–natural gas dual–fuel marine engines. This study, for the first time, compared and analyzed the effects of single and split injection strategies on the combustion process in a marine medium-speed dual-fuel engine with a natural gas substitution rate of 93.3%. Optimal strategies were compared for single injection [Case A: start of injection (SOI)=−15° crank angle (CA) after top dead center (ATDC)] and split injection (Case B: SOI1=−60°CA ATDC, SOI2=−10°CA ATDC). The analysis of Cases A and B revealed that employing a split pilot diesel injection strategy enhances engine thermal efficiency—Case B had a 0.77% increase in efficiency compared with Case A. More importantly, the split injection strategy proved to be more effective in reducing emissions; compared with Case A, Case B had a 36.3% and 49.4% decrease in NOx and CH4 emissions, respectively. A deeper examination of the combustion process in Case B revealed that the reactivity in specific cylinder regions was enhanced, thereby increasing the flame propagation speed in those areas. Moreover, the strategy reduced the proportion of pilot diesel diffusion combustion, leading to lower high temperatures and aiding in the reduction of NOx formation. These findings provide a technological reference for improving energy conversion efficiency and facilitating cleaner combustion in future applications of low-carbon fuels in dual-fuel marine engines. [ABSTRACT FROM AUTHOR]

This document discusses the importance of computational and data-driven modeling in understanding and optimizing combustion in reciprocating engines and gas turbines. The Paris Agreement's goals to reduce greenhouse gas emissions and global warming necessitate the reduction of pollutants emitted by transportation and energy production. While new technologies like electrification and carbon capture are emerging, internal combustion engines and gas turbines remain crucial in the short and medium term. Computational modeling allows for the investigation of various operating conditions, reducing costs and risks. The document includes research articles and a review on the role of micro gas turbines in distributed energy production, covering topics such as reducing emissions in internal combustion engines, exploring alternative fuels, and improving the efficiency of gas turbines. [Extracted from the article]

Due to increasing emissions and global warming, in parallel with the increasing world population and energy needs, IMO has introduced severe rules for ships. Energy efficiency on ships can be achieved using the organic and inorganic Rankine cycle (RC) driven by exhaust heat from marine diesel engines. In this study, toluene, R600, isopentane, and n-hexane as dry fluids; R717 and R718 as wet fluids; and R123, R142b, R600a, R245fa, and R141b as isentropic fluids are selected as the working fluid because they are commonly used refrigerants, with favorable thermal properties, zero ODP, low GWP and are good contenders for this application. The cycle and exergy efficiencies, net power, and irreversibility of marine diesel engine exhaust-driven simple RC and RC with a recuperator are calculated. For dry fluids, the most efficient fluid at low turbine inlet temperatures is n-hexane at 39.75%, while at high turbine inlet temperatures, it is toluene at 41.20%. For isentropic fluids, the most efficient fluid at low turbine inlet temperatures is R123 with 23%, while at high turbine inlet temperatures it is R141b with 23%. As an inorganic fluid, R718 is one of the most suitable working fluids at high turbine inlet temperatures of 300 °C onboard ships with a safety group classification of A1, ODP of 0, and GWP100 of 0, with a cycle efficiency of 33%. This study contributes to significant improvements in fuel efficiency and reductions in greenhouse gas emissions, leading to more sustainable and cost-effective maritime operations. [ABSTRACT FROM AUTHOR]

Decarbonizing maritime transport hinges on transitioning oil-fueled ships (98.4% of the fleet) to renewable and low-carbon fuel types. This shift is crucial for meeting the greenhouse gas (GHG) reduction targets set by the IMO and the EU, with the aim of achieving climate neutrality by 2050. Ammonia, which does not contain carbon atoms that generate CO2, is considered one of the effective solutions for decarbonization in the medium and long term. However, the concurrent increase in nitrogen oxide (NOx) emissions during the ammonia combustion cycle, subject to strict regulation by the MARPOL 73/78 convention, necessitates implementing solutions to reduce them through optimizing the combustion cycle. This publication presents a numerical study on the optimization of diesel and ammonia injection phases in a ship's medium-speed engine, Wartsila 6L46. The study investigates the exhaust gas emissions and combustion cycle parameters through a high-pressure injection strategy. At an identified 7° CAD injection phase distance between diesel and ammonia, along with an optimal dual-fuel start of injection 10° CAD before TDC, a reduction of 47% in greenhouse gas emissions (GHG = CO2 + CH4 + N2O) was achieved compared to the diesel combustion cycle. This result aligns with the GHG reduction target set by both the IMO and the EU for 2030. Additionally, during the investigation of the thermodynamic combustion characteristics of the cycle, a comparative reduction in NOx of 4.6% was realized. This reduction is linked to the DeNOx process, where the decrease in NOx is offset by an increase in N2O. However, the optimized ammonia combustion cycle results in significant emissions of unburnt NH3, reaching 1.5 g/kWh. In summary, optimizing the combustion cycle of dual ammonia and diesel fuel is essential for achieving efficient and reliable engine performance. Balancing combustion efficiency with emission levels of greenhouse gases, unburned NH3, and NOx is crucial. For the Wartsila 6L46 marine diesel engine, the recommended injection phasing is A710/D717, with a 7° CAD between injection phases. [ABSTRACT FROM AUTHOR]

Particle emissions from marine activities next to gaseous emissions have attracted increasing attention in recent years, whether in the form of black carbon for its contribution to global warming or as fine particulate matter posing a threat to human health. Coastal areas are particularly affected by this. Hence, there is a great need for shipping to explore alternative fuels that both reduce greenhouse gas emissions, as anticipated through IMO, and also have the potential to reduce particle emissions significantly. This paper presents a comparative study of the particulate emissions of two novel synthetic/biofuels (GTL and HVO), which might, in part, substitute traditionally used distillate liquid fuels (e.g., MDO). HFO particulate emissions, in combination with an EGCS, formed the baseline. The main emphasis was laid on particle concentration (PN) and particulate matter (PM) emissions, combining gravimetric and particle number measurements. Measurements were conducted on a 0.72 MW research engine at different loads (25%, 50%, and 75%). The results show that novel fuels produce slightly fewer emissions than diesel fuel. Results also exhibit a clear trend that particle formation decreases as engine load increases. The EGCS only moderately reduces particle emissions for all complaint fuels, which is related to the formation of very fine particles, especially at high engine loads. [ABSTRACT FROM AUTHOR]

There is a consensus on the need to reduce the emissions of carbon compounds. The increase in global greenhouse gas (GHG) emissions in the maritime industry poses a serious challenge to environmental sustainability, climate change, and the operating costs of ships. This article shows how hybrid versus diesel propulsion technology for ships can help reduce carbon dioxide (CO2) emissions and fuel consumption, and how these changes can be achieved. The need to reduce exhaust emissions and the increasing need for the shipping industry to seek alternative fuels means that existing regulations for marine engines and engine emissions are being updated almost constantly and new regulations are being formulated. The cost implications of the new regulations may lead to an increase in emissions as engines with lower fuel consumption are chosen, i.e., larger marine engines. Alternative approaches are needed to reduce CO2 emissions and fuel consumption, which could ultimately lead to hybrid propulsion for ships. This paper examines the current state of greenhouse gas emissions in shipping by analyzing the CO2 emissions and operating costs of two ships of the same type with similar technical and technological characteristics and different propulsion systems to gain insight into the problem. This paper compares the reductions in CO2 emissions, fuel consumption, and fuel costs for two suction hopper dredgers with standard diesel and hybrid propulsion. The technical characteristics, CO2 emissions, fuel consumption, and price of the two ships were analyzed to determine the advantages and disadvantages of each propulsion system. The novelty of this study is that two suction hopper dredgers from the same company with similar technical–technological characteristics but different propulsion systems were used for the case study and a mathematical procedure for calculating CO2 and other greenhouse gasses was presented in comparison, all to determine to what extent and in what way the hybrid propulsion system of a ship can contribute to reductions in CO2 emissions and fuel costs at the ship and company levels compared to a standard diesel propulsion system. This comparative analysis shows how much lower CO2 emissions, fuel consumption, and fuel cost savings can be expected when using a hybrid propulsion system compared to a standard diesel propulsion system. Finally, a conclusion is drawn on the efficiency and environmental compatibility of the two systems. [ABSTRACT FROM AUTHOR]

In diesel-ignited natural gas marine dual-fuel engines, the pilot diesel injection timing (PDIT) determines the premixing time and ignition moment of the combustible mixture in the cylinder. The PDIT plays a crucial role in the subsequent development of natural gas flame combustion. In this paper, four PDITs (− 8 °CA, − 6 °CA, − 4 °CA, and − 2 °CA) were studied. The results show that the advancement of PDIT increased the engine's power, thermal efficiency, and natural gas flame spread velocity, and increased NO emissions and CH4 emissions of the marine engine. The PDIT affected the ignition delay period and the rapid combustion period to a greater extent than the slow combustion period and the post combustion period. With each 2 °CA advancement of PDIT, the engine's power increased by 69.87 kW, thermal efficiency increased by 0.42%, radial flame spread velocity increased by 2 m/s, axial flame spread velocity increased by 1.7 m/s, NO emissions increased by 6.1%, and CH4 emissions increased by 3.75%. [ABSTRACT FROM AUTHOR]

The capability of operational marine diesel engines to adapt to renewable and low-carbon fuels is considered one of the most influential methods for decarbonizing maritime transport. In the medium and long term, ammonia is positively valued among renewable and low-carbon fuels in the marine transport sector because its chemical elemental composition does not contain carbon atoms which lead to the formation of CO2 emissions during fuel combustion in the cylinder. However, there are number of problematic aspects to using ammonia in diesel engines (DE): in-tensive formation of GHG component N2O; formation of toxic NOx emissions; and unburnt toxic NH3 slip to the exhaust system. The aim of this research was to evaluate the changes in combustion cycle parameters and exhaust gas emissions of a medium-speed Wartsila 6L46 marine diesel engine operating with ammonia, while optimizing ammonia injection intensity within the limits of Pmax, Tmax, and minimal engine structural changes. The high-pressure dual-fuel (HPDF) injection strategy for the D5/A95 dual-fuel ratio (5% diesel and 95% ammonia by energy value) was investigated within the liquid ammonia injection pressure range of 500 to 2000 bar at the identified optimal injection phases (A −10° CAD and D −3° CAD TDC). Increasing ammonia injection pressure from 500 bar (corresponding to diesel injection pressure) in the range of 800–2000 bar determines the single-phase heat release characteristic (HRC). Combustion duration decreases from 90° crank angle degrees (CAD) at D100 to 20–30° CAD, while indicative thermal efficiency (ITE) increases by ~4.6%. The physical cyclic deNOx process of NOx reduction was identified, and its efficiency was evaluated in relation to ammonia injection pressure by relating the dynamics of NOx formation to local combustion temperature field structure. The optimal ammonia injection pressure was found to be 1000 bar, based on combustion cycle parameters (ITE, Pmax, and Tmax) and exhaust gas emissions (NOx, NH3, and GHG). GHG emissions in a CO2 equivalent were reduced by 24% when ammonia injection pressure was increased from 500 bar to 1000 bar. For comparison, GHG emissions were also reduced by 45%, compared to the diesel combustion cycle. [ABSTRACT FROM AUTHOR]

Steam-methane reformers are one of the most effective environmental systems used to obtain hydrogen with the effect of temperature. This study investigated hydrogen production efficiency numerically with exhaust waste heat. Two different scenarios were studied parametrically at five various engine loads. In this study, steam methane reactor temperature change, hydrogen, CO and CO 2 formation amounts were determined according to each exhaust temperature and mass flow rate. As a result of the study, the temperature changes for the scenario 1 and scenario 2 conditions of the steam methane reformer were examined and it was found that the maximum temperature change was 26.7% at the 25% engine load condition. The maximum hydrogen production mass flow rate in proportion to the temperature was approximately 7020 g/h in scenario 2 at 25% engine load condition. Radical CO formation showed that system performance is not realized efficiently enough. The study's significant finding is that increasing the temperature and using catalysts throughout the system increases hydrogen production. • A 2D CFD reforming model is developed to predict H 2 production. • Investigation of H 2 production potential with waste heat of marine diesel engine. • CFD shows that H 2 production increases with rising temperature. • The effect of modified exhaust temperatures on H 2 production was simulated. • The use of catalysts obviously promotes H 2 production. [ABSTRACT FROM AUTHOR]

The current study is focused on the analysis of methods and means for reducing marine engine exhaust and greenhouse gases (GHGs). The research method consists in identifying equipments that have been applied in the case of small four-stroke marine engines used as emergency generators on board large ships, specifically the Cummins Qsb6.7-G16 model. The results, which were demonstrated by practical experiences of the different possible configurations for the engine studied showed high potential for reducing emissions, but the most suitable alternative is the Selective Catalytic Reduction (SCR). [ABSTRACT FROM AUTHOR]

Post-combustion carbon capture is a direct and effective way for onboard carbon capture. Therefore, it is important to develop onboard carbon capture absorbent that can both ensure a high absorption rate and reduce the energy consumption of the desorption process. In this paper, a K2CO3 solution was first established using Aspen Plus to simulate CO2 capture from the exhaust gases of a marine dual-fuel engine in diesel mode. The lean and rich CO2 loading results from the simulation were used to guide the selection and optimization of the activators used in the experiment. During the experiment, five amino acid salt activators including SarK, GlyK, ProK, LysK, and AlaK and four organic amine activators including MEA, PZ, AEEA, and TEPA were used. Experiments only considered the activation effect of CO2 loading between lean and rich conditions. The results showed that after adding a small amount of activator, the absorption rate of CO2 by the absorbent was greatly improved, and the activation effect of organic amine activators was stronger than that of amino acid salts. Among the amino acid salts, the SarK-K2CO3 composite solution showed the best performance in both absorption and desorption. Among the amino acid salts and the organic amino activators, SarK-K2CO3 showed the best performance in strengthening the CO2 desorption while PZ-K2CO3 enhanced the CO2 absorption process the most. In the study of the concentration ratio, it was found that when the mass concentration ratio was 1:1 for SarK:K2CO3 and PZ:K2CO3, the CO2 absorption and desorption processes improved well. [ABSTRACT FROM AUTHOR]

For many years, the Suez Canal (also known as the Suez Route) has been the main route connecting Europe and Asia. However, compared with the Suez Route, the Northeast Passage could save up to 41% of the journey. The ship carbon intensity index (CII) rating system of the International Maritime Organization (IMO) came into effect in 2023. This study took an existing bulk carrier on the Europe–Asia route as an example to calculate the attained CII values at different sailing speeds. It was found that, regardless of external factors, when the ship speed dropped from 14.4 knots (85% maximum continuous rating (MCR)) to 12.6 knots (55% MCR), the corresponding attained CII value decreased from 6.48 g/ton·nm to 5.19 g/ton·nm. Therefore, sailing speed was the key factor influencing the attained CII value, and it was independent of the shipping distance. In addition, when the ship's sailing output power was between 85% MCR and 75% MCR, for every 5% decrease in MCR, its attained CII value would decrease by 0.13 g/ton·nm, and the fuel consumption amount would decrease by 1 ton/day. However, when the ship sailed at an output power of 75% MCR to 55% MCR, for every 5% decrease in MCR, the attained CII value would decrease even more, up to 0.26 g/ton·nm. In addition, the attained CII value would be reduced by up to 100% and fuel consumption amount would be reduced by up to 1.5 ton/day, resulting in a 50% fuel saving effect. Therefore, to obtain a better CII rating, the optimal ship speed should be set between 75% MCR and 55% MCR according to the wave and wind strengths. However, although slow-speed sailing is the most efficient factor, the number of sailing days would also be extended. Through the ratio created by dividing the distance of the Northeast Passage by the Suez Route, whether the Northeast Passage has the benefit of balancing shipping schedules could be judged. The outcome indicated that a ratio lower than 1 would result in a more balanced shipping schedule. Compared with 2019, the number of ships sailing through the Northeast Passage in 2021 increased significantly by 132%, and the average dead weight tonnage of the ships also rose from 18,846 tons to 23,736 tons. This study found that, with the implementation of the carbon reduction policy of the CII rating, ships sailing through the Northeast Passage could continue to develop toward the trend of large-sized vessels and steady increase in ship number. [ABSTRACT FROM AUTHOR]

In this study, the influence of direct steam injection (DSI) on the performance and emissions of marine engines is investigated. Simulation models are developed and tested based on experimental data. Steam is obtained by waste heat recovery in a marine engine. The limitations of DSI parameters are investigated based on the exhaust gas temperature. The steam quantity and temperature decrease with a decrease in load. The results show that steam mass plays an important role in NOx reduction and improving power. For a steam/fuel ratio of 1.27 at 100% load, the brake power improved by 3.09% and NOx emissions decreased by 4.67%. A higher degree of improvement is obtained with an increase in steam mass. The steam temperature and injection timing only slightly influenced the brake power and NOx emissions. When steam-injection timing improved to 12°CA at 100% load with injection duration decreasing from 85°CA to 25°CA, brake power improved from 3,485.7 to 3,529.7 kW. All of this demonstrates that the DSI approach has excellent energy-saving and emission reduction potential for marine engines. The steam-injection strategy should be optimized in the future. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) is a major pollutant in the exhaust of marine diesel engines, which seriously endangers human health and the atmospheric environment, and how to reduce particulate matter emissions from marine engines has become a key research direction in the field of environmental protection and diesel engines. In this study, we analyzed the components and sources of PM from marine engines and conducted tests on the performance of Wärtsilä 20DF Diesel Particulate Filter (DPF) catalysts to verify the capture efficiency, gaseous pollutant removal rate, regeneration effect and the relationship between carbon loading and pressure loss of DPF catalysts in the context of Tier III emission regulations. The results showed that PM emissions of 20DF in diesel mode after adding the DPF system meet the requirements of the regulatory limit, but the pressure drop of the engine increases after adding the DPF system. Therefore, numerical simulation was used to optimize the DPF structure by evaluating the system velocity field, flow field distribution uniformity and system pressure drop to improve the pressure drop. [ABSTRACT FROM AUTHOR]

In this study, the ammonia-diesel stratified injection (ADSI) is explored on a marine low-speed engine., The effect of three injection timings(IT S = −3°CA ATDC, −1°CA ATDC, and 1°CA ATDC) coupling with three diesel energy fractions (DEF S = 1%,5%, and 10%) on combustion and emission characteristics of the engine under full load is investigated. The results show that advancing IT has an obvious effect on increasing peak cylinder pressure while enhancing DEF can increase the heat release rate under ADSI mode, and the ignition delay time is less than original diesel engine. The ADSI has higher indicated thermal efficiency than original diesel engine except for IT of 1°CA ATDC coupling DEF of 1%, and its combustion efficiency can be significantly improved. Furthermore, the NO x increases with advancing IT and increasing DEF while the unburned ammonia is the opposite. The NO x emissions are all lower than original diesel engine under different IT coupling DEF. Advancing IT is an effective measure to reduce unburned ammonia. The greenhouse gas (GHG) can be greatly reduced. A priority strategy of the IT coupling DEF is proposed through comprehensive comparison under the ADSI mode, which can meet the Tier III regulations. This strategy reduces indicated specific fuel consumption and GHG around by 4% and 94% compared with the diesel engine respectively, and the combustion efficiency reaches more than 99%. The unburned ammonia is limited to less than 150 ppm. • A new ammonia-diesel stratified injection (ADSJ) mode was explored in detail. • The effect of multi-parameter coupling was studied on combustion and emissions. • The ADSJ mode was easier ignition than the original diesel engine. • The ADSJ had better combustion characteristics than the original diesel engine. • An optimized parameter control strategy is proposed. [ABSTRACT FROM AUTHOR]

The quaternary blends (diesel–biodiesel-vegetable oil-alcohol) offer enormous potential for reducing fossil fuel usage and mitigating air pollution caused by marine diesel engines. Biodiesel and alcohol are alternate fuels possessing high oxygen content, ensuring clean combustion. Vegetable oil is beneficial in saving diesel contribution and increasing engine lubrication. The objective of the present work was to reduce the dependency on conventional diesel and to come up with cleaner fuel that can also improve engine performance. This experimental work aims to lower exhaust emissions by fueling a single-cylinder, four-stroke direct-injection diesel engine with novel quaternary blends comprising diesel (50%), sunflower biodiesel (25%), sunflower oil (5%), and alcohol (20%). In order to develop cleaner fuel than diesel, different quaternary blends were prepared by varying the length of the carbon chain of alcohols in the blends, namely, DBOEth20, DBOProp20, DBOBut20, DBOHep20, and DBODec20. The performance emissions of quaternary blends were tested at varied engine loads from 5 to 20 Nm (full load), while engine speed was fixed at 1800 rpm. The results indicate that DBOProp20 resulted in the lowest fuel consumption and highest thermal efficiency. DBOProp20 reduced CO2, NOx, and smoke emissions by 19.6%, 9.9%, and 85.7%, as compared to diesel. However, DBODec20 succeed in mitigating CO emission by 41.37% at 100% load. DBOBut20 proved to be most promising in reducing UHC emission by a maximum of 71.69% at 100% load. The highest BTE of 10.98% with lowest BSFC of 13.04% was recorded for DBOProp20 at 100% engine load, in comparison to pure diesel. [ABSTRACT FROM AUTHOR]

Most large commercial vessels are propelled by low-speed two-stroke diesel engines due to their fuel economy and reliability. With increasing international concern about emissions and the rise in oil prices, improvements in engine efficiency are urgently needed. In the present work, a zero-dimensional model for a low-speed two-stroke diesel engine is developed that considers the exhaust gas bypass and geometry structures for the gas exchange model. The model was applied to a low-speed two-stroke 7G80 ME-C9 marine diesel engine and validated with engine shop test data, which consisted of the main engine performance parameters and cylinder pressure diagrams at different loads. The simulation results were in good agreement with the experimental data. Thus, the model has the ability to predict engine performance with good accuracy. After model validation, the variations in compression ratio, fuel injection timing, exhaust gas bypass valve opening portion, exhaust valve opening timing, and exhaust valve closing timing effects on engine performance were tested. Finally, the influence level of different parameters on engine performance was summarized, which can be used as a reference to determine the reasons for high fuel consumption in some cases. The developed engine performance model is considerable in digital twins for performance simulation, health management, and optimization. [ABSTRACT FROM AUTHOR]

Techniques such as exhaust gas recirculation (EGR) and water-in-fuel emulsions (WFEs) can significantly decrease NOx emissions in diesel engines. As a disadvantage of adopting EGR, the afterburning period lengthens owing to a shortage of oxygen, lowering thermal efficiency. Meanwhile, WFEs can slightly reduce NOx emissions and reduce the afterburning phase without severely compromising thermal efficiency. Therefore, the EGR–WFE combination was modeled utilizing the KIVA-3V code along with GT power and experimental results. The findings indicated that combining EGR with WFEs is an efficient technique to reduce afterburning and enhance thermal efficiency. Under the EGR state, the NO product was evenly lowered. In the WFE, a considerable NO amount was created near the front edge of the combustion flame. Additionally, squish flow from the piston's up–down movement improved fuel–air mixing, and NO production was increased as a result, particularly at high injection pressure. Using WFEs with EGR at a low oxygen concentration significantly reduced NO emissions while increasing thermal efficiency. For instance, using 16% of the oxygen concentration and a 40% water emulsion, a 94% drop in NO and a 4% improvement in the Indicated Mean Effective Pressure were obtained concurrently. This research proposes using the EGR–WFE combination to minimize NO emissions while maintaining thermal efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • The combustion characteristics of ammonia/hydrogen in marine engine were studied; • HPDP-1C mode improves engine performance; • A 30 % hydrogen was proposed based on the overall performance of marine engines; • The NO x emissions should be concerned for ammonia/hydrogen combustion; Studies show that blending ammonia and hydrogen fuels is a feasible approach to achieve zero carbon emissions in internal combustion engines. The prevalent use of high-pressure dual fuel (HPDF) injection primarily originates from its high efficiency and relatively low emission. However, ammonia exhibits poor ignition performance, and adding hydrogen increases cylinder temperatures, leading to the formation of nitrogen oxides. The present study explores various injector arrangements, ignition modes, and ammonia/hydrogen blend ratios to devise effective combustion strategies and mitigate NO x emissions. Comparative analysis reveals that the injector arrangement in close position of ammonia and hydrogen exhibits superior performance in terms of indicated power, thermal efficiency, and heat release rate. Regarding ignition modes, transitioning from ammonia/hydrogen blend compression ignition mode to hydrogen piloted ammonia mode increases the indicated power by 0.7 %, while remarkably raising NO x emissions by 29.4 %. Moreover, increasing hydrogen content enhances indicated power by 3.7 % but elevates nitrogen oxide emissions by a factor of 2.2, while reducing ammonia and hydrogen escape, with a maximum not exceeding 0.058 %. Consequently, a 30 % ammonia/hydrogen blend ratio coupled with HPDF-1C arrangement is recommended for marine engines, prioritizing combustion stability and lower NO x emissions. The findings of the present research offer invaluable insights into advancing the development of ammonia/hydrogen blended fuel engines and provide a guideline for blending fuels in engineering and industrial applications. [ABSTRACT FROM AUTHOR]

The reported findings help to understand the treatment technology for studying shipping emissions and air pollution, especially in the context of near-zero emissions. Ship emissions primarily consist of two categories: air pollutants such as SOx, NOx, PM, CO, and NMVOCs, as well as greenhouse gases, including CO SB 2 sb , CH SB 4 sb , and N SB 2 sb O [[5], [7]]. However, engine combustion will produce a lot of harmful emissions such as particulate matter (PM), sulfur oxides (SOx), and nitrogen oxides (NOx), which cause severe pollution to the atmosphere and marine environment [[4]]. [Extracted from the article]

Ship emissions are one of the main sources of air pollution in port cities. The prosperous maritime trade has brought great harm to the air quality of port cities while promoting the development of the world economy. During the berthing process, ship auxiliary machines emit a large amount of air pollutants, which have a great impact on air quality and public health. Alternative marine fuels are being studied and used frequently to reduce ship emissions. This research was carried out to investigate the gaseous and particles emission characteristics of a marine diesel engine during the application of experimental biodiesel fuels. To study the influence of mixed fuels on engine performance, measurements were made at different engine loads and speeds. Different diesel fuels were tested using various ratios between biodiesel and BD0 (ultra-low sulfur diesel) of 0%, 10%, 30%, 50%, 70%, 90%, and 100%. The results indicated the use of biodiesel has little influence on the combustion performance but has a certain impact on exhaust emissions. The octane number and laminar flame speed of biodiesel are higher than those of BD0, so the combustion time of the test diesel engine is shortened under the mixed mode of biodiesel. In addition, a high ratio of biodiesel leads to a decrease of the instantaneous peak heat release rate, causing the crank angle to advance. As the biodiesel blending ratio increased, most of the gaseous pollutants decreased, especially for CO, but it led to an increase of particle numbers. The particle size distribution exhibits a unimodal distribution under various conditions, with the peak value appearing at 30–75 nm. The use of biodiesel has no effect on this phenomenon. The peak positions strongly depend on fuel types and engine conditions. The particulate matter (PM) emitted from the test engine included large amounts of organic carbon (OC), which accounted for between 30% and 40% of PM. Whereas the elemental carbon (EC) accounted for between 10% and 20%, the water-soluble ions components accounted for 6–15%. Elemental components, which accounted for 3–8% of PM emissions, mainly consisted of Si, Fe, Sn, Ba, Al, Zn, V, and Ni. Generally, biodiesel could be a reliable alternative fuel to reduce ship auxiliary engine emissions at berth and improve port air quality. [ABSTRACT FROM AUTHOR]

IMO has pushed out strict regulations to limit marine diesel engine emissions. EGR is a mature measure to reduce NOx emissions which would lead PM emissions risen. In this paper, An EGR system combined with a scrubber was built on a marine diesel engine. Based on the experimental platform, the characteristics of PM emissions were studied when the engine burning two kinds of sulfur diesel oils. The results showed that the particle size concentration curves show multimodal distribution and the average particle sizes increased. Most of the PM emissions were distributed in the nuclear mode interval. Moreover, EGR scrubber had a significant effect on removing PM with an efficiency of over 98% and the weighted value of PM emissions was 22.136 mg / kWh, which met China's first and second-stage emission regulations and US EPA Tier 4 emission regulations. [ABSTRACT FROM AUTHOR]

NO has been described as one of the most harmful gases produced under high-temperature conditions from combustion chambers of marine diesel engines. Researchers have stressed the adverse effects of marine diesel engine emissions on human health and other biological systems. The International Convention on the Prevention of Pollution from Ships (MARPOL Annex VI) established NOx global emission limits. It provided a platform to encourage technological innovations toward reduction in NO emissions. Several specialized methods have been in application for NOx emission reductions, but their operational processes and technical efficiencies remain poorly understood. Therefore, a comprehensive review has been conducted on various NO emission reduction methods, classified into primary and secondary methods. The formation process of NOx was assessed in detail, and the multiple methods in application toward NO emission reduction were evaluated based on their technological efficiencies. It was established that scavenge humidification and SNCR-selective noncatalytic reduction is the most efficient NOx emission reduction method, given their emission reduction potentials at 80% and 95%, respectively. [ABSTRACT FROM AUTHOR]

Ocean oil slicks can be attributed to natural seepages or to anthropogenic discharges. To date, the global picture of their distribution and relative natural and anthropogenic contributions remains unclear. Here, by analyzing 563,705 Sentinel-1 images from 2014–2019, we provide the first global map of oil slicks and a detailed inventory of static-and-persistent sources (natural seeps, platforms, and pipelines). About 90% of oil slicks were within 160 kilometers of shorelines, with 21 high-density slick belts coinciding well with shipping routes. Quantified by slick area, the proportion of anthropogenic discharges was an order of magnitude greater than natural seepages (94 versus 6%), in contrast to the previous estimate quantified by volume during 1990–1999 (54 versus 46%). Our findings reveal that the present-day anthropogenic contribution to marine oil pollution may have been substantially underestimated. [ABSTRACT FROM AUTHOR]

Multiple operating modes and flexible outputs are typical characteristics of multimode electricity-cooling cogeneration systems (ECCS). The present study proposes an innovative multimode ECCS driven by exhaust gas from marine engines and presents a corresponding thermodynamic system model. The thermodynamic performance, distribution region of operating modes, and exergoeconomic performance of the system are comprehensively investigated under various operational conditions. A novel comprehensive evaluation index, namely, the system net output per unit total mass flow rate (NOPF), is introduced to ensure that the analysis of system performance remains unaffected by the variations in the mass flow rate of the working fluid. The findings indicate that the operational modes exhibit diverse responses to influencing variables, while the distribution region of the operational modes is more sensitive to the separation ratio of the working fluid flow rate (X). Under the electricity-cooling generation mode of the system, the maximum NOPF reaches 156.01 kJ⋅kg−1. Furthermore, the proposed system achieves a peak exergy efficiency (η ex) of 13.83 %, concurrently decreasing the energy production cost (EPC) to a mere 0.0981 Dollar·kWh−1. Finally, this study offers new research insights that can inform future regional analyses of other multimodal and multigeneration systems. • A novel multimode electricity-cooling cogeneration system (ECCS) was proposed. • A new comprehensive performance evaluation index (NOPF) was proposed. • The distribution of operating modes and the performance of the system were examined. • The electricity-cooling generation mode achieved a peak NOPF of 156.01 kJ⋅kg−1. • Balanced system performance reached 13.83 % (η ex) and 0.0981 Dollar·kWh−1 (EPC). [ABSTRACT FROM AUTHOR]

In recent years, the International Maritime Organization (IMO), Europe, and the United States and other countries have set up different emission control areas (ECA) for ship exhaust pollutants to enforce more stringent pollutant emission regulations. In order to meet the current IMO Tier III emission regulations, an after-treatment device must be installed in the exhaust system of the ship power plant to reduce the ship NOx emissions. At present, selective catalytic reduction technology (SCR) is one of the main technical routes to resolve excess NOx emissions of marine diesel engines, and is the only NOx emission reduction technology recognized by the IMO that can be used for various ship engines. Compared with the conventional low-pressure SCR system, the high-pressure SCR system can be applied to low-speed marine diesel engines that burn inferior fuels, but its working conditions are relatively harsh, and it can be susceptible to operational problems such as sulfuric acid corrosion, salt blockage, and switching delay during the actual ship tests and ship applications. Therefore, it is necessary to improve the design method and matching strategy of the high-pressure SCR system to achieve a more efficient and reliable operation. This article summarizes the technical characteristics and application problems of marine diesel engine SCR systems in detail, tracks the development trend of the catalytic reaction mechanism, engine tuning, and control strategy under high sulfur exhaust gas conditions. Results showed that low temperature is an important reason for the formation of ammonium nitrate, ammonium sulfate, and other deposits. Additionally, the formed deposits will directly affect the working performance of the SCR systems. The development of SCR technology for marine low-speed engines should be the compromise solution under the requirements of high sulfur fuel, high thermal efficiency, and low pollution emissions. Under the dual restrictions of high sulfur fuel and low exhaust temperature, the low-speed diesel engine SCR systems will inevitably sacrifice part of the engine economy to obtain higher denitrification efficiency and operational reliability. [ABSTRACT FROM AUTHOR]

The objective of this review is to illustrate the emissions of biodieselblends employed in marine engines, focusing on the impact of mixed fuels on marine engine emission characteristics, discussing the limitations of the application of biodiesel-diesel blends in marine engines and suggesting possible solutions. The sulfur oxide (SOx), carbon monoxide (CO), carbon dioxide (CO2), particulate matter (PM) and hydrocarbon (HC) emissions are reduced to a great extent when biodiesel-diesel blends are used in marine diesel engines. The excessively fast burning rate increases the temperature in the cylinder, thereby promoting nitrogen oxides (NOX) generation. Research shows that biodiesel will reduce dependence on imported petroleum and reduce emissions of ship exhaust. Biodiesel and its blended fuels have bright application prospects as alternative fuels for marine diesel. [ABSTRACT FROM AUTHOR]

Although the exhaust gas recirculation (EGR) technology has been proven effective to decrease the marine engine's nitrogen oxides (NOx) emissions, it is associated with a considerable fuel consumption increase and challenges to the engine–turbocharger matching. This study aims to parametrically optimise the EGR and turbocharging system settings of a large marine two-stroke engine with the objective of obtaining the highest engine efficiency whilst ensuring compliance with the prevailing NOx emissions limits. Two typical configurations of the investigated engine (baseline and alternative) are modelled in the GT-SUITE software. Parametric simulations are performed with EGR rates up to 40% along with cylinder bypass rates up to 50%, and the simulation results are analysed to quantify the impact of the engine operation with EGR on the performance and NOx emissions parameters. For the baseline engine configuration, the EGR rate increase considerably deteriorates the brake specific fuel consumption (BSFC), which is attenuated by opening the cylinder bypass valve. The optimal combinations of the EGR and cylinder bypass rates for each operating point are identified for both configurations. Following the comparative assessment between the two engine configurations, recommendations for the engine operating modes are proposed, leading to BSFC improvement in the region of 0.7 to 2.9 g/kWh. This study provides insights for the operational settings optimisation of two-stroke engines equipped with EGR systems, contributing towards the reduction of the associated environmental carbon footprint. [ABSTRACT FROM AUTHOR]

Black carbon (BC) mass concentration from internal combustion engines can be quantified using a variety of different BC measurement techniques. We compare the relative response of several commercial instruments with different measurement principles to different types of marine exhaust emissions. Exhaust samples were generated using a high-speed 4-stroke marine diesel engine at various engine operating conditions from low to high engine loads. Three different fuel types—diesel, distillate marine oil grade A (DMA) and intermediate fuel oil (IFO)—were used to generate soot particles with a wide range of physical, chemical and optical properties. Based on the standard deviation of the results at all engine conditions evaluated in the present study, the overall spread between the instruments was 24% for diesel, 30% for DMA and 37% for IFO samples. For samples with extremely high organic content (at 10% engine power), the agreement was poor and the standard deviation of the mass concentrations estimated from different instruments was 50% for diesel with OC/EC ≈ 45 and 72% for DMA with OC/EC ≈280. For IFO particles, more scattered mass concentrations were reported by different instruments at all engine loads, possibly due to very complex chemical composition and different optical properties in comparison with well-characterized soot particles. We explain the differences in reported values by combining information on exhaust composition with the measurement principles used in each instrument. [ABSTRACT FROM AUTHOR]

In modern conditions, there is an active interest in continuing research to reduce harmful emissions of marine engine exhaust gases into the atmosphere and prepare ships for the use of technologies with zero level of these emissions. It is known that the European Green Deal concept announced by the European Union is aimed not only at the modernization of the inland vessels, and coordinated qualitative change in its composition, but within this framework also at the large-scale implementation of the energy transition as the most effective way to achieve zero emissions into the atmosphere. At the same time, environmental aspects and issues of energy efficiency are considered as a complex task of transition to energy efficient eco-navigation. To date, for the European inland navigation participants, the stages of reducing harmful emissions into the atmosphere are clearly defined and regulated with established numerical standard (reference) values for each of the components (CO, HC, NOx, PM). As for energy efficiency, discussions are still ongoing at the international level about the advisability of introducing criteria according to the principle established by the International Maritime Organization for ships based on the specific mass of harmful emissions (in terms of CO2) per unit of transport work. At the same time, there is an understanding of the specifics of navigation conditions and technologies for transporting goods, which makes us return to comparing energy efficiency and economy indicators. The team of authors made an attempt to find and offer the most comprehensive approach to assessing the energy efficiency and economy of the inland navigation vessels operation, in particular for Danube vessels, with the maximum possible consideration of the features of their operation. An integrated approach to the use of estimated indicators of the efficiency of the existing pushers with heavy convoys allows to achieve an increase in the energy efficiency of the operation of the existing fleet, as well as lead to an improvement in environmental indicators. [ABSTRACT FROM AUTHOR]

The article briefly describes the problem of air pollution caused by sea-going ships and the resulting restrictions on the emission of toxic and harmful chemical compounds in the exhaust of marine engines, introduced by the International Maritime Organization (IMO) under the International Convention for the Prevention of Sea Pollution from Ships (MARPOL 73/78). Such emissions provide a significant metrological problem, not only for the owners of operating sea-going ships, but also for shipyards, maritime administration offices and environmental protection inspectors. For this reason, the article's author is developing research issues related to the diagnosing the exhaust emissions of marine engines under operating conditions, i.e. with limited control (measurement) susceptibility. This is particularly important in the period of intensive implementation of a new category of marine fuel, so-called modified fuels with low sulphur content. As part of the problem, a computational model of the parameters characterising the exhaust emissions of a marine engine in operation is presented in this article. This model is based on the measurement of the engine's control parameters, using a standard (stationary) measurement system and a portable diagnostic system, configured for the purpose of this research. Presented here are representative measurements and calculation results (both obtained by the author and provided by the manufacturer) from the chemical exhaust gas emissivity of one of the ship engines operated. These confirm the adequacy of the calculation model developed and the diagnostic effectiveness of the measuring equipment applied. The methodology developed for experimental testing may also be implemented for the operation of other types of marine engines, provided that the basic chemical composition of the fuel supply and the engine load characteristics and hourly fuel consumption are known. Moreover, there is the possibility of indicating the cylinders and measuring the chemical composition of exhaust gases in the high-temperature part of the exhaust duct. [ABSTRACT FROM AUTHOR]

Natural gas marine engines are widely used in the commercial shipping. It is a hot research topic for carbon reduction, energy saving, and emission reduction in shipping. The over-expansion cycle with natural gas high-pressure direct-injection (HPDI) is a promising approach for reducing fuel consumption and emissions in marine engine. Two types of over-expansion cycles in a large-bore (500 mm) low-speed dual-fuel engine were investigated and compared. The variable compression (VC) cycle decreases the effective compression ratio by adjusting the exhaust valve closing (EVC) timing, and the variable expansion (VE) cycle raises the effective expansion ratio by varying the exhaust valve opening (EVO) timing and scavenging ports opening (SPO) timing. A specific sleeve mechanism was designed to precisely control the opening and closing of scavenging ports. The results reveal that the VC cycle exhibits an operable limit with a delay of 40 °CA in EVC, while the VE cycle has a limit with a delay of 60 °CA in EVO. The scavenging effect obtains improvement in the VC cycle, whereas it deteriorates in the VE cycle. Both the two cycles lead to reduced peak pressure and extended combustion duration. Compared to the baseline, the VC cycle and VE cycle can reduce nitrogen oxides (NO x) emissions by a maximum of 51.9% and 70.7%, respectively. However, the VE cycle can even reduce the equivalent indicated specific fuel consumption (EISFC) by 1.14 g/kWh when the EVO is delayed by 5 °CA. Importantly, the VE cycle exhibits a more favorable cost-effectiveness and potential for NO x emission reduction compared to the VC cycle, and it also demonstrates the capability to optimize NO x and EISFC simultaneously. This provides a method to produce cleaner marine engines with less fuel consumption in the future. [ABSTRACT FROM AUTHOR]

Water/steam direct injection is an effective method to lower emissions and improve the power of engines by using waste heat recovery (WHR). The parameters of water injection (WI) and steam injection (SI) were analyzed at compression stroke on the effect of brake power and emissions in marine engines, including injected timing, mass, and temperature. The results demonstrated that NOx emissions were substantially reduced by using WI method. However, brake power was also decreased. The SI method not only decreased NOx emissions but also improved brake power. The NOx emissions were ascended with increasing temperature and delaying injected timing of water. Opposing trends were found for SI method. The injected mass has a large effect on power and emissions compared with the influence of temperature and timing. The NOx emissions can be reduced by 72.8% with 2.08% power loss when the 20 g of water was injected into the cylinder at −50 °CA, 15 bar and 400 K. The NOx emissions can be reduced by 38.9% with 24.7% power improvement when the same mass of superheated steam with 500 K of temperature was injected into the cylinder. It can be obvious that SI method can increase power while reducing fuel consumption and emissions. [ABSTRACT FROM AUTHOR]

Black carbon (BC) emissions intensify global warming and are linked to adverse health effects. The International Maritime Organization (IMO) considers the impact of BC emissions from international shipping. A prerequisite for the anticipated limits to BC emissions from marine engines is a reliable measurement method. The three candidate methods (photoacoustic spectroscopy (PAS), laser-induced incandescence (LII), and filter smoke number (FSN)) selected by the IMO were evaluated with extensive ship exhaust matrices obtained by different fuels, engines, and emission control devices. A few instruments targeted for atmospheric measurements were included as well. The BC concentrations were close to each other with the smoke meters (AVL 415S and 415SE), PAS (AVL MSS), LII (Artium-300), MAAP 5012, aethalometers (Magee AE-33 and AE-42), and EC (TOA). In most cases, the standard deviation between instruments was in the range of 5–15% at BC concentrations below 30 mg Sm−3. Some differences in the BC concentrations measured with these instruments were potentially related to the ratio of light-absorbing compounds to sulphates or to particle sizes and morphologies. In addition, calibrations, sampling, and correction of thermophoretic loss of BC explained differences in the BC results. However, overall differences in the BC results obtained with three candidate methods selected by the IMO were low despite challenging exhaust compositions from marine diesel engines. Findings will inform decision making on BC emission control from marine engines.

A study is presented to determine the technical, regulatory, and economic feasibility of a coastal research vessel (named the "Zero-V") powered solely by hydrogen fuel cells. Feasibility is examined in the context of science mission profiles of particular significance in coastal oceanography that require a modern, capable, general-purpose coastal research vessel. These missions translate into the primary Zero-V vessel requirements against which technical feasibility is assessed. Hull form analysis indicated a trimaran design enables a vessel that can meet all of the space and volume requirements as well as for fitment of the machinery, service, and control spaces necessary for operation of the vessel. To meet speed and range (endurance) requirements, the vessel needs to be constructed of aluminum to reduce weight. The beam (56 feet), length (170 feet) and draft (12 feet) of the vessel enable it to dock at all primary ports of call. With 1800 kW of installed proton exchange membrane (PEM) fuel-cell power for primary propulsion, the cruising speed is 10 knots. With 10,900 kg of consumable LH 2 stored in two LH 2 tanks, the range of the vessel is 2400 nautical miles, with an endurance of 15 days. Both the greenhouse gas (GHG) and criteria pollutant (NO x , HC, PM 10) emissions were estimated based on a complete "well-to-waves" (WTW) analysis. Using renewable hydrogen, the annual WTW GHG emissions predicted for the Zero-V are 91.4% less than those from an equivalent vessel running on conventional diesel fuel. Analysis of the WTW criteria pollutant emissions show that hydrogen PEM fuel-cell technology can reduce these emissions below stringent U.S. Environmental Protection Agency (EPA) Tier 4 marine diesel engine emissions limits regardless of whether the hydrogen is made using natural gas or renewable methods. The capital construction cost is estimated to be ~ $79 M, not unreasonable when compared to other modern diesel-fueled research vessels of similar size and capabilities. The operations and maintenance (O&M) costs of the Zero-V were estimated to be 7.7% higher than operating the equivalent diesel-fueled vessel at the assumed fuel prices for LH 2 made from steam reforming of fossil natural gas. The approach to safety for the Zero-V is described in terms of the arrangement of hazardous areas on the vessel. Regulatory review of the vessel design by the United States Coast Guard (USCG) and the Class society DNV GL found no fundamental or "show-stopping" design concerns that would prevent eventual deployment of the Zero-V. Overall, this study found it feasible from technical, regulatory, and economic perspectives to design, build and operate a coastal research vessel powered solely by hydrogen fuel cells. [ABSTRACT FROM AUTHOR]

The scientific article deals with new directions in reducing the harmful emissions in the exhaust gases of marine engines. For the first time in the world shipping practice, a scientific and production company "Eco-Auto-Titan" Ukraine used a fuel oil filter catalyst (FOFC) on the vessels of the "Ukrainian Danube Shipping Company" (the PJSC "UDP") All research work was carried out by the Danube Institute NU "OMA" with the monitoring and confirmation of the results by Institute for Environment and Energy Conservation (Kyiv). [ABSTRACT FROM AUTHOR]

For accurately analyzing the emission performance of dual-fuel engine, an experimental scheme was designed based on response surface methodology, and the central composite design was applied to this study. Speed and load were used as the influencing factors, and NOX, CO, CO2, and HC were the corresponding responses. Data of dual-fuel engine emissions were utilized to set up mathematical model to analyze the emission characteristics of engine. Results of data analysis were found to match the original engine's emissions. The significance of the model test showed that P-values of mathematic model are less than 0.05, which verified the validity of the designed model. Speed of 800 r/min and load of 64% were found to have better emission performance with higher desirability of 65.4% for the tested engine. Corresponding emissions were 0.16% of CO, 3.97% of CO2, 463.92 ppm of NOX, and 224.27 ppm of HC. [ABSTRACT FROM AUTHOR]

Purpose: The emission from marine engines has a crucial effect on energy economy and environment pollution. One of the effective emission reduction schemes is to minimize the friction loss of main friction pairs such as cylinder liner-piston ring (CLPR). Micro-groove textures were designed to accomplish this aim. Design/methodology/approach: The authors experimentally investigated the effects of micro-groove textures at different cylinder liner positions. The micro-groove texture was fabricated on samples by chemical etching and cut from the real CLPR pair. Sliding contact tests were conducted by a reciprocation test apparatus. Findings: The average friction coefficient of grooves at 30° inclination were reduced up to 58.22% and produced better tribological behavior at most conditions. The operating condition was the critical factor that determined the optimum texture pattern. The surface morphology indicated that textures could produce smoother surfaces and less scratches as compared with the untextured surface. Originality/value: Inclined grooves and V-grooves were designed and applied to real CLPR pairs. The knowledge obtained in this study will lead to practical basis for tribological design and manufacturing of CLPR pair in marine diesel engines. [ABSTRACT FROM AUTHOR]

The characteristics of black carbon and nitrogen oxide reduction versus the water content of emulsion fuel were studied by numerical methods, and a method of reducing fuel consumption was achieved by adjusting the turbocharger compression ratio. The results of the combustion period characteristics, versus the three types of emulsion fuel and the turbocharger compression ratios, shows that the combustion period is shortened in the order of CR00 > CR01 > CR02 > CR03, according to the compression ratio of the turbocharger. As the fuel water content increases, the combustion period is shortened in the order of EMDO16 < EMDO13 < EMDO10. The nitrogen oxide and black carbon reduction was because the combustion period increased, with increasing compression ratio, while the combustion period was shortened, with increasing moisture content of emulsion fuel. This also caused is an increase in the combustion pressure and a shortening of the combustion period, due to the expansion of the volume, in turn due to the micro-explosion of water. This may be due to the shortening of the post combustion period and the reduction of black carbon emissions. In addition, combustion was accelerated in the order—CR00 > CR01> CR02> CR03. By optimizing the water content of the emulsion fuel and turbocharger compression ratio, while considering the exhaust emission and combustion state, reduction of the fuel consumption rate and output improvement are shown. [ABSTRACT FROM AUTHOR]

Increasing demands on energy efficiency and environmental acceptance are being imposed on marine propulsion plants. The fulfilment of the conditions set by the MARPOL Convention, Annex VI, regarding the emissions from exhaust gases of marine diesel engines is of particular interest. This paper presents the development and validation of a zero-dimensional, single-zone diesel engine numerical model. Presented numerical model is based on the law of conservation of energy and mass and solving the resulting differential equations. The single-zone model will serve as the basis for a model where the cylinder space is divided into two or three zones during combustion. In this way, the multi-zone model will allow the modelling of nitrogen oxide emissions with satisfactory accuracy. Validation of the diesel engine model was carried out for the Wärtsilä 12V50DF 11700 kW motor designed to drive a synchronous alternator. Obtained results and deviations of certain parameters in the operation of the engine with respect to the data obtained from the measurements on the test bed, are more than satisfactory regarding complexity of the numerical model. This confirmed the usability of the model for research purposes to optimize the marine diesel engine. [ABSTRACT FROM AUTHOR]

• Exhaust gas CO 2 absorption (EGCA) system was installed on MW-scale marine engine. • EGCA performance was certified as per the test procedure described in NTC 2008. • 29/30 wt%(E2/E3 mode) of CO 2 absorption was obtained by EGCA system. • Pretreatment reactor needs to be combined for stable operation of EGCA system. The management of CO 2 emissions from fossil fuel-powered ships has been considered for complying with future enhancements in CO 2 emission regulations in the shipbuilding industry. These regulations are (or will be) enforced using indexes such as the energy efficiency design index, energy efficiency existing index, energy efficiency operational indicator, and carbon intensity indicator. Hence, developing technology for reducing CO 2 emissions from ships is necessary. This paper reports on the CO 2 absorption performance of a pilot-scale CO 2 capture system installed on a 1.075-MW HiMSEN 5H22CDF engine. The proposed technology is an exhaust gas CO 2 absorption (EGCA) system. Our CO 2 capture system is based on an exhaust gas cleaning system, which is already commercialized to reduce SO x emissions from ships that use heavy fuel oil. The CO 2 absorption performance of the EGCA system was evaluated following the test procedure described in the NO x Technical Code 2008 (NTC 2008). Under the certified test procedure described in NTC 2008, the EGCA system exhibited 29/30 wt% (E2/E3 test mode) of CO 2 absorption. On the basis of the test results, we expect that ships will be able to comply with future CO 2 emission regulations by using the proposed EGCA system. [ABSTRACT FROM AUTHOR]

Container ships are the type of ships that produce the most emissions in maritime transport. In container transportation not only in navigation but also at container ports, a lot of emissions are formed. Ports are generally close by and highly interacted with the inner parts of the city, the impacts of the gas emissions are quite high on people. The study investigated port selection criteria, in terms of cost, efficiency and especially in terms of environmental impacts in order to create awareness. Container port selection problem was solved using fuzzy TOPSIS (The Technique for Order Preference by Similarity to Ideal Situation) method considering the perspective of carriers. In the study, the container port selection was carried out among the four largest container ports in Turkey. [ABSTRACT FROM AUTHOR]

The SOx emissions of the marine engine are regulated by international maritime conventions. In this paper, the effect of various parameters, including SO2 partial pressure, liquid to gas ratio (L/G), alkalinity and pH, was investigated by seawater scrubbing experiment in a turbulent contact absorber (TCA) and a spray absorber (SA) on a laboratory scale. The experimental data showed that the desulfurization efficiency of TCA was mainly dependent on the value of L/G and irrelevant to the changing way of L/G; the appropriate L/G of TCA was 2.3 dm³/m³ and pH of effluent water was 2.4-2.8 at the L/G of 1.1-2.8 dm³/m³. Comparatively, the desulfurization efficiency of increasing liquid flow rate was better than that of decreasing gas flow rate in the SA experiment. At the gas velocity of 1.58 m/s and L/G of 2.3 dm³/m³, the desulfurization efficiencies and drop pressures of TCA and SA were 75.9% and 42.4%, 690 and 260 Pa, respectively. The results indicate that TCA chosen as an absorber is likely to be a competitive desulfurization technique for controlling marine diesel emission. [ABSTRACT FROM AUTHOR]

Highlights • The spray and evaporation characteristics in the large marine diesel engine were investigated. • Three kinds of optical diagnostic technologies were used. • The empirical correlations of spray tip penetrations and SMDs were updated. Abstract The spray and evaporation characteristics of injector used in the large marine diesel engine directly affect the combustion and emission performance of marine engine. But these characteristics are rarely studied. In this work, three kinds of optical diagnostic technologies (backlight high speed imaging technique, UV-LAS and LIF/MIE) were applied to measure the spray liquid and vapor penetrations, spreading angles, SMDs and the distribution of fuel vapor mass of an injector used in the large marine engine under different conditions. The detailed description of the experiment setups and principle of the three optical diagnostic techniques are provided in this work. The experimental results show that the liquid and vapor penetrations decrease with increasing the ambient density. Increasing the ambient temperature can reduce the liquid penetration, but has no obvious effect on the vapor penetration. For spreading angle, the ambient temperature and ambient density are the main influence factors. Increasing the injection pressure is an effective method to reduce SMD, and also the ambient temperature acts as an important role in the fuel evaporation process. What's more, the empirical correlations of spray tip penetrations and SMDs have been updated to fit the spray characteristics of marine diesel engine injector. In general, this work is helpful to understand the spray and evaporation characteristics within diesel-fueled marine engine conditions, and can provide valuable direction for the design of marine engine combustion system. [ABSTRACT FROM AUTHOR]

Highlights • A novel system for removing NO in marine diesel engine exhaust gases was studied. • The NO removal efficiency was 100% in 0.15 mol/L or 0.2 mol/L Na 2 S 2 O 8 solution at 80 °C. • Urea which can remove nitrate promoted the NO removal. • The Na 2 S 2 O 8 /urea system not only highly removes the NO but also reduces the nitrate in wastewater. Abstract NO is the main precursor of photochemical smog. Since the SCR system of marine diesel engines has many disadvantages, this paper proposes an effective wet method to remove NO from the exhaust gases of marine diesel engines. Experiments were performed in a bubble column reactor to study the absorption of NO using sodium persulfate (Na 2 S 2 O 8)/urea ((NH 2) 2 CO) solutions from a simulated gas stream. The effects of various operating parameters on NO removal were investigated, including reaction temperature, urea concentration, Na 2 S 2 O 8 concentration and the initial pH value of Na 2 S 2 O 8 /urea solutions. The experimental results showed that the NO removal efficiency increased with increasing reaction temperature (25–80 °C) and increasing Na 2 S 2 O 8 concentration (0.01–0.2 mol/L). When the concentration of urea was higher than 0.5 mol/L at 60 °C, 1 mol/L at 70 °C or 2 mol/L at 80 °C, the NO removal efficiency increased with the increase of urea concentration (0.1–4 mol/L). The highest NO removal efficiency was 99.7%, occurring at 80 °C when the concentrations of Na 2 S 2 O 8 and urea were 0.1 mol/L and 4 mol/L, respectively, and the concentration of nitrate was 14.93 mg/L. The optimal urea conditions were well below the legal limit of 60 mg/L. The NO removal efficiency increased with the increase of initial pH value within the herein investigated range of 7–9. All the experimental data showed that the novel system not only achieved effective NO removal efficiency, but also reduced the nitrate in wastewater, which could thus be applied to denitrification of marine engine exhaust gases. [ABSTRACT FROM AUTHOR]