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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]

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]

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]

• Port injection combustion of methanol is limited to 50% methanol energy fraction. • Direct injection combustion of methanol allows for 95% methanol energy fraction. • NOx emissions reduce between 1% and 84% for all methanol cases. • Indicated thermal efficiency increases up to 4% comparing to diesel operation. Methanol is identified as a transition fuel to improve the environmental footprint of shipping operations. However, high methanol shares cannot be achieved in premixed combustion marine dual-fuel engines. This study aims at parametrically investigating the impact of two types of methanol injection, namely port and direct injection, on marine engines by employing CFD modelling. A large medium speed marine engine with nominal power of 10.5 MW at 500 rev/m is considered. CFD models are developed for the engine diesel and dual fuel modes with methanol port or direct injections. Several cases with methanol energy fractions ranging up to 50 % for the port injection and 95 % for the direct injection cases are investigated. The developed CFD models were validated for the investigated engine operation in the diesel gas modes, as well as for a small engine with methanol port injection. A parametric study considering the engine settings and methanol energy fraction is performed to identify the engine settings and limits for the combustion knock-free operation for high methanol shares. Subsequently, the comparative assessment of the investigated marine engine performance and emissions parameters is performed for the considered cases. This study results reveal that the methanol direct injection can use up to 95 % methanol energy fraction retaining knock-free combustion conditions, whilst reducing NOx emissions by 85 %. The engine indicated thermal efficiency increases at higher methanol energy fractions for direct injection, whereas opposite trade-offs are exhibited for premixed combustion. Methanol use shortens the combustion durations compared to the diesel mode, reducing the maximum temperature by 1–3 %. This study provides valuable insights delineating the impact of the settings to the marine engines performance and emissions trade-offs, hence contributing to developing methanol fuelled marine engines. [ABSTRACT FROM AUTHOR]

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]

The performance of marine engines has been consecutively improved over the years, and current marine engines are more efficient year by year. 10.3390/jmse8020109 8 Witkowski K. Research of the Effectiveness of Selected Methods of Reducing Toxic Exhaust Emissions of Marine Diesel Engines. According to this, the Special Issue, "Marine Engines Performance and Engines", published as a book [[1]], was prepared to collect works relating to marine engine performance and emissions in general. [Extracted from the article]

The article discusses the results of actions performed by marine engine manufacturers towards the reduction of emission of harmful substances in the exhaust gas from these engines. The discussion is limited to main engines produced by MAN B&W. A model is proposed to describe the process of emission of harmful substances from Diesel engines based on the semi-Markov process, discrete in states and continuous in the operating time. The states of this process are: engine ability state (s1) and engine inability state (s2). A method to calculate probabilities P1 and P2 of the appearance of states s1 and s2 is proposed. State s1 is interpreted as corresponding to the inequality ekek(dop), where ek represents the mass of harmful substances emitted by the engine during its operation and ek(dop) is the maximum mass of emission of these substances permitted by relevant regulations. [ABSTRACT FROM AUTHOR]

The purpose of this research was to achieve the best performance, combustion and emission characteristics of a marine engine fueled with hydrogen (5%, 10% and 15% energy fraction), water (2, 4 and 6 wt%) and rapeseed methyl ester (RME) blend fuel by the multi-objective optimization. Based on the experimental results of the engine at 50%, 75% and 100% loads, the computational fluid dynamics (CFD) model was developed, and an improved chemical kinetic mechanism was developed to simulate the fuel combustion process. The response surface methodology (RSM) was used to optimize the combustion and emission characteristics of the marine diesel engine. The result showed that the hydrogen and water can improve the combustion and emission characteristics of the marine engine. The best solution was to select the desirable value of 0.632, and the engine achieves the best state by fueling R + 15H + 2.5W at 74.69% load. At the point, the optimum values of brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), nitrogen oxide (NO x), hydrocarbon (HC) and carbon monoxide (CO) emissions were 208.31 g/kW·h, 39.22%, 941.21 ppm, 325.86 ppm and 1073.4 ppm, respectively. For this study, adding appropriate hydrogen and water to biodiesel can achieve efficient, low carbon and clean combustion in marine engine. • Effects of hydrogen/biodiesel/water blend fuels on combustion and emission characteristics are compared. • Optimum blend fuel is obtained for diesel engine. • An improved 3D model and chemical kinetics mechanism are developed. • The performance optimization was carried out by the response surface methodology. [ABSTRACT FROM AUTHOR]

Marine engines often use diesel as an alternative fuel to improve the economy. In recent years, waste oil, biodiesel and alcohol fuel are the most famous research directions among the alternative fuels for diesel. With the rapid development of the shipping industry, the air of coastal areas is becoming increasingly polluted. It is now necessary to reduce the emission of marine engines to meet the strict emission regulations. There are many types of alternative fuels for diesel oil and the difference of the fuel may interfere with the engine emissions; however, PM, HC, CO and other emissions will have a negative impact on SCR catalyst. This paper reviews the alternative fuels such as alcohols, waste oils, biodiesel made from vegetable oil and animal oil, and then summarizes and analyzes the influence of different alternative fuels on engine emissions and pollutant formation mechanism. In addition, this paper also summarizes the methods that can effectively reduce the emissions of marine engines; it can provide a reference for the study of diesel alternative fuel and the reduction of marine engine emissions. [ABSTRACT FROM AUTHOR]

• Regulations on marine diesel engine emissions are listed and compared. • The contribution of marine diesel engine emissions to regional emissions is given. • The emission levels of marine diesel engines are reviewed. • Integrated multi-pollutant aftertreatment technologies are reviewed. Marine diesel engines, which provide main power source for ships, mainly contribute to air pollution in ports and coastal areas. Thus there is an increasing demand on tightening the emission standards for marine diesel engines, which necessitates the research on various emission reduction strategies. This review covers emission regulations and emission factors (EFs), environmental effects and available emission reduction solutions for marine diesel engines. Not only the establishment of the emission control areas (ECAs) in the regulations but also many experiments show high concerns about the sulfur limits in fuels, sulfur oxides (SOx) and nitrogen oxides (NOx) emissions. Research results reveal that NOx emissions from marine diesel engines account for 50% of total NOx in harbors and coastal regions. Sulfur content in fuel oil is an important parameter index that determines the development direction of emission control technologies. Despites some issues, biodiesel, methanol and liquefied nature gas (LNG) play their important roles in reducing emissions as well as in replacing fossil energy, being promising fuels for marine diesel engines. Fuel-water emulsion (FWE) and exhaust gas recirculation (EGR) are effective treatment option for NOx emissions control. Common rail fuel injection is an effective fuel injection strategy to achieve simultaneous reductions in particulate matter (PM) and NOx. Selective catalytic reduction (SCR) and wet scrubbing are the most mature and effective exhaust aftertreatment methods for marine diesel engines, which show 90% De-NOx efficiency and 95% De-SOx efficiency. It can be concluded that the integrated multi-pollutant treatment for ship emissions holds great promise. [ABSTRACT FROM AUTHOR]