Effect of multiple injection strategies on emissions and performance in the Wärtsilä 6L 46 marine engine. A numerical approach (original) (raw)
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International Journal of Engine Research, 2010
Reductions in the emissions of nitrogen oxides (NO x) and soot from marine diesel engines can be supported by employing multiple-injection strategies, similar to those used in automotive engines. In the present computational study, the possibility of improving the operation of a large two-stroke marine diesel engine at full load by implementing an appropriate pilot injection is explored. A KIVA-3-based computational fluid dynamics code is used, coupled with an evolutionary algorithm. Multi-objective engine optimization is performed by parameterizing the fuel injection profiles in terms of four design variables, which fully define the pilot and main injections. Two objective functions are defined: the final NO x concentration and the specific fuel oil consumption (SFOC), both normalized by the corresponding values of a reference case of continuous injection. Three problem setups have been considered: first, an unconstrained problem; second, a problem constrained by the maximum cylinder pressure; third, a problem constrained by both the maximum pressure and the minimum work output per engine cycle. It is found that, in both the unconstrained and the one-constraint problems, the optimum solutions are characterized by substantial improvements in the NO x emissions (of the order of 15-20 per cent) and the SFOC (of the order of 2 per cent). The improvements are less pronounced when both constraints are imposed. A detailed sensitivity analysis of the effects of each of the design variables is presented.
Revista de Chimie, 2019
Maritime University of Constanta, Faculty of Naval Electromechanics, 104 Mircea cel Batran Str., 900663, Constanta, Romania Combustion inside diesel engine cylinders is the critical factor that controls the emission and combustion gases. Fuel injection in the engine cylinder is the decisive factor in the combustion of diesel engines and, consequently, combustion can be effectively controlled if the fuel injection process is efficiently controlled. From this perspective, the simulation of the complex processes of fuel injection in diesel engines in various situations can make a positive contribution to the optimization of marine propulsion systems. Also, correct dimensioning of the injection system components and its optimization and, implicitly, the combustion parameters, can have positive results in the context of reducing the impact of combustion gases of internal combustion engines, on the greenhouse effect and global warming.
Evaluation of Pilot Injections in a Large Two-Stroke Marine Diesel Engine, Using CFD and T-φ Mapping
In 2002 the European Commission adopted a European Union strategy to reduce atmospheric emissions from seagoing ships. The strategy reports on the magnitude and impact of ship emissions in the EU, and sets out a number of actions to reduce the contribution of shipping to health and climate change. One possible approach for the reduction of NO X and soot emissions of marine diesel engines is the use of multiple injection strategies, similar to the ones used in automotive diesel engines. In this way, diesel combustion could be optimized with respect to pollutant emissions, without compromising fuel efficiency.
The implementation of multiple-injection strategies in marine Diesel engines may partially contribute to compliance with emission regulations, while also maintaining a high engine performance. The present computational study investigates the possibility of implementing Partially Premixed Compression Ignition (PPCI) combustion in two-stroke marine Diesel engines. In particular, the concept is implemented in terms of pilot fuel injection with proper orientation of the spray jets, and tested by Computational Fluid Dynamics (CFD) simulations in a large two-stroke marine Diesel engine operating at full load. An early fuel injection is accompanied by long ignition delay, thus allowing fuel-air premixing.
Journal of KONES, 2015
The advancing emissions requirements and the customer demand for increased performance and fuel efficiency are forcing the diesel engine technology to keep improving. In particular, the large diesel engines are undergoing to a significant restriction in emission standards. Reaching the new limits requires innovative solutions, improved calibration and controls of the engine combustion technology, as well as the optimization of the injection system that has experienced the most fundamental development over the last decade. The objective of the paper is to present preliminary results of an investigation for the development of an efficient combustion system for marine diesel engines. The effect of different engine parameters on performance and engine out emissions were evaluated. Specifically, different nozzle geometries, injection pressure, injection timings were taken into account. The investigation was carried out both experimentally and numerically. Three different nozzles geometries for three different values of the start of injection were tested. The in-cylinder pressure, rate of heat release, NOx and soot were evaluated for a high load engine condition. The experimental activity was carried out on a large displacement single cylinder direct injection diesel engine equipped with a high-pressure common rail injection system able to manage multiple injections. The engine test bench was equipped with an external air supercharger able to set high air boost levels. The system controls the intake air temperature by means of a heater exchanger. The numerical investigation was carried out using the commercial CFD STAR-CD code in a three-dimensional domain including the cylinder head and piston bowl. Combustion behaviour was simulated using the 3 Zones Extended Coherent Flame Model (ECFM3Z).
The Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines, 2017
A modified 2-D Flamelet model was further developed and validated under various engine operating conditions. It was extended from 2-D flamelet model (C. Hasse, 2004) by simplifying the calculation procedures in extremely rich and lean region which can reduce the CPU time from the original one. Additionally, the collapsing method (C. Felsch, 2009) was introduced, and the model was extended to quadruple injection by applying the collapsing method twice. The simulation cases cover multiple injection strategies including triple and quadruple injection with different EGR rate, and the simulations were carried out by a commercial light-duty diesel engine with n-heptane skeletal chemical mechanism of which considers 29 species and 52 reactions. Simulation results show that the model can capture auto-ignition, mass and heat transfer of each fuel stream, in-cylinder pressure, heat release rate and NOx emissions under multiple fuel stream conditions. Particularly, the model could analyze the combustion process by the interaction of multiple fuel stream, which gives important information on the emissions reduction by multiple injection strategies. Based on the model, the effect on the advanced injection strategies to the reduction of emissions was quantitatively investigated. The quantitatively investigated results could be specified by analyzing how the change of injection timing, duration and the number of injection event can affect the solution of governing equation and corresponding mixture fraction domain.
Journal of Marine Science and Engineering
The medium-speed diesel engine in diesel-electric propulsion systems is increasingly used as the propulsion engine for liquefied natural gas (LNG) ships and passenger ships. The main advantage of such systems is high reliability, better maneuverability, greater ability to optimize and significant decreasing of the engine room volume. Marine propulsion systems are required to be as energy efficient as possible and to meet environmental protection standards. This paper analyzes the impact of split injection on fuel consumption and NOx emissions of marine medium-speed diesel engines. For the needs of the research, a zero-dimensional, two-zone numerical model of a diesel engine was developed. Model based on the extended Zeldovich mechanism was applied to predict NOx emissions. The validation of the numerical model was performed by comparing operating parameters of the basic engine with data from engine manufacturers and data from sea trials of a ship with diesel-electric propulsion. The...
Investigation of injection timing and different fuels on the diesel engine performance and emissions
2020
Start of fuel injection and fuel type are two important factors affecting engine performance and exhaust emissions in internal combustion engines. In the present study, a one-dimensional computational fluid dynamics solution with GT-Power software is used to simulate a six-cylinder diesel engine to study the performance and exhaust emissions with different injection timing and alternative fuels. Starting the fuel injection was from 10 °CA BTDC to the TDC with an interval between two units and from alternative fuel bases (diesel), including methanol, ethanol, diesel, and ethanol compounds, biodiesel and decane was used. To validate the model, a comparison is made between simulation data and experimental data (including torque and power) showing the validation error is less than 6.12% and indicating the software model validation. Also, the modeling results show that decane fuel has higher brake power and brake torque of more than 6.10 % while fuel is injected at 10 °CA BTDC compared t...
International journal of automotive engineering, 2016
Modern diesel engines should have higher pollutant emissions standards with better performance and by using split injection strategies which could optimize the air – fuel mixture, this purpose could be achieved. After achieving the successful validation between modeling and experimental results for both single and double injection strategies, for the first time and in this paper, double injection strategies with new nozzle configuration were used in which number of nozzle holes were doubled and located below the previous holes and then double injection strategies were implemented in a case that for each pulse of injections upper or below holes were used, then this study focused on the effects of the new nozzle configuration holes angle in each pulse of injections. This study confirms that split injection could decrease Nox emission, because it has lower maximum in-cylinder temperature than single injection case due to its separate second stage of combustion, also results showed that...
Energies, 2013
An advanced numerical investigation has been carried out in order to study the effect of multiple injection strategies on Caterpillar heavy-duty diesel engine emissions. Both different injected fuel percentages for each pulse and several dwells between main and post phase were investigated via computational fluid dynamics (CFD) and large eddy simulation (LES). Two sets of simulations were taken into account for 10% and 20% exhaust gas recirculation (EGR) fractions. In the first one, the main injection was split into two identical phases, while in the second one into three pulses. Within each set, three strategies were considered, increasing the amount of fuel injected during the main and concurrently decreasing the post pulse. Overall, 48 simulations were employed, since four different dwells between the last phase of the main and post injection were considered. Results show that the pollutant emissions minimization has been obtained for the Schemes injecting 65% and 70% of fuel for both two and three split strategies, but for different values of dwell. In fact, emissions very close to each other for NO x and particulate matter have been reached for these cases. Reductions of about −30% and −71% were respectively obtained for NO x and soot in comparison with experimental emissions related to the single injection case.