The use of a Phenomenological, multizone combusion Model to investigate emissions from Marine diesel engines (original) (raw)
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Possibilities to Reduce Pollutant Emissions in Naval Diesel Engines
Mechanical Testing and Diagnosis
The combustion process is, by far, the most important and complex process that takes place in engines. Its importance is given by the fact that it provides the flow of energy used in the engine and is the source of all pollutant emissions, the efficiency of the engine being directly influenced by it. The mechanisms of combustion are particularly complex and are not fully known even today, the most difficult problem being the mechanisms of mixture formation and the chemistry of the combustion process. Over time, depending on the evolution of knowledge in the field and computer technology, various mathematical models have been developed, which have. Emission estimation and theoretical verification, in the first phase, of the solutions applicable to in-service enginescould greatly reduce research and production costs, given that there are a variety of engines onboard ships and measurements in operation are very difficult.
Journal of Thermal Analysis and Calorimetry, 2020
The main energy source in marine industry is fossil fuel. Diesel engines are main power supply in sea transport at present times and will also be in the future. Energy conservation and environmental protection are the main problems that engine manufacturers are facing. Researchers have been making a lot of effort over the last decades to analyse energy conversion in large two-stroke engines. A 1-dimensional large two-stroke low-speed diesel engine model is developed, along with a multi-zone combustion model (MZCM), in which the losses of exchanging working medium and gas composition are calculated in the whole engine, unlike the preceding 0-dimensional and quasi-dimensional engine models that are only calculated in engine cylinder chamber. The model of a low-speed two-stroke marine diesel engine is calibrated and validated with experimental data and is used for simulation and analysis of the engine performance, combustion behaviour and emission of harmful exhaust gases. Large two-stroke marine diesel engines are problematic for modelling due to very few researches on this issue, due to the unsuitability of applying model on a low-speed two-stroke big diesel engines, large number of parameters that affect combustion behaviour, shape of ports and exhaust valves, working medium flow as well as because of shape of combustion chambers in these engines. For the reasons above, this research paper and its experiments contribute to better understanding large two-stroke low-speed marine diesel engine process. Analysis of engine characteristic was done by varying the most important parameters. Optimization of fuel injection characteristic and exhaust timing is achieved. The parameter of changing injection profile from classic to pre-injection was performed, and the effects on engine performance, NOx, CO and soot emissions were showed. With a pre-injection profile it is possible to reduce NOx emission by 9%, but a decrease in engine power is significant. Keywords Combustion • Modelling • Engine performance • NOx emission List of symbols NOx Nitrogen oxides SOx Sulphur oxides PM Particulate matter HC Hydrocarbons CO Carbon monoxide CO 2 Carbon dioxide 3D Three dimensional w air Mass fraction of air w FV Mass fraction of fuel vapour w CP Mass fraction of combustion products AF CP Air fuel ratio of combustion products W FB Mass fraction of burned fuel d(m c ⋅u) d Change of the internal energy in the cylinder p c ⋅ dV d Piston work dQ F d Fuel heat input dQ w d
International Journal of Energy Research, 2003
A two-zone model for the calculation of the closed cycle of a direct injection (DI) diesel engine is presented. The cylinder contents are taken to comprise a non-burning zone of air and another homogeneous zone in which fuel is continuously supplied from the injector holes during injection and burned with entrained air from the air zone. The growth of the fuel spray zone, consisting of a number of fuel-air conical jets equal to the injector nozzle holes, is carefully modelled by incorporating jet mixing to determine the amount of oxygen available for combustion. Application of the mass, energy and state equations in each one of the two zones yields local temperatures and cylinder pressure histories. For calculating the concentration of constituents in the exhaust gases, a chemical equilibrium scheme is adopted for the C-H-O system of the 11 species considered, together with chemical rate equations for the calculation of nitric oxide (NO). A model for the evaluation of soot formation and oxidation rates is incorporated. A comparison is made between the theoretical results from the computer program implementing the analysis, with experimental results from a vast experimental investigation conducted on a fully automated test bed, direct injection, standard 'Hydra', diesel engine located at the authors' laboratory, with very good results, following a multiparametric study of the constants incorporated in the various sub-models. Pressure indicator diagrams and plots of temperature, NO, soot density and of other interesting quantities are presented as a function of crank angle, for various loads and injection timings, elucidating the physical mechanisms governing combustion and pollutants formation.
Optimization of Ship Propulsion Diesel Engine to Fulfill the New Requirements for Exhaust Emissions
Impacts of exhaust gas emissions on the environment and air pollution from ships have received considerable attention in the past few decades. Due to the characteristics of the combustion process, typical for large marine two-stroke low-speed engines, and the use of residual fossil fuels, the world's fleet emits into the atmosphere significant amount of pollutants such as nitrogen oxides (NO x), carbon monoxide (CO), carbon dioxide (CO 2), hydrocarbons (HC), sulphur oxides (SO x) and carbon particles (PM). Impact assessment of the process of their formation, emitted amounts and the influence of emission are important factors for decision making in regulation development and also for engine designers who aim to improve low-speed two-stroke marine engines, for further tightening of regulations regarding limiting emissions. This paper consists of three parts: the first section describes the injection and combustion process in lowspeed two-stroke marine engines, the second part describes the formation of the exhaust gas emissions as a product of the combustion process and the third part, in which the known techniques to reduce harmful emissions that are currently used in low-speed two-stroke marine engines are described. 1
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. Our interest is in investigating the potential for emissions reduction and overall optimization of combustion in large two-stroke marine diesel engines, using numerical simulation. In this context, we study the effects of advanced injection strategies by utilizing Computational Fluid Dynamics (CFD) tools. We use the KIVA-3 code as the modeling platform, with improved models for spray breakup, autoignition and combustion. Here, we report first results, corresponding to pilot injections, which are visualized for the fuel injection and combustion processes, and are also mapped on temperature-equivalence ratio charts (T-φ maps). This analysis reveals important information on pollutant formation mechanisms in large marine diesel engines.
Journal of Mechanical Science and Technology, 2008
Taking into account the complexity and cost of a direct experimental approach, the recourse to simulation, which can also predict inaccessible information by measurement, offers an effective and fast alternative to apprehend the problem of pollutant emissions from internal combustion engines. An analytical model based on detailed chemical kinetics employed to calculate the pollutant emissions of a marine Diesel engine in general gave satisfactory results compared to experimentally measured results. Especially, the nitric oxide (NO) emission values were found to be higher than the limiting values tolerated by the International Maritime Organization (IMO). Thus, this study was undertaken to reduce to the maximum these emissions. The reduction of pollutant emissions is apprehended with exhaust gas recirculation (EGR).
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.
Analysis of Exhaust Gas Emission in the Marine Two-Stroke Slow-Speed Diesel Engine
Brodogradnja, 2016
This paper explores the problem of exhaust emissions of the marine two-stroke slowspeed diesel engines. After establishing marine diesel engine regulations and defining the parameters influencing exhaust emissions, the simulation model of the marine two-stroke slow-speed diesel engine has been developed. Furthermore, the comparison of numerical and experimentally obtained data has been performed, resulting in achieving the model validity at 100% load, which represents a requirement for further exhaust gas analysis. Deviations obtained at the real engine and the model range from 2% to 7%. An analysis of the influential parameters such as compression ratio, exhaust valve timing and fuel injection timing has been performed. The obtained results have been compared and conclusions have been drawn.
NOx emission reduction in marine diesel engines
2018
Pollutant gases emitted from marine thermal engines cause degradations of the eco-systems. The aim of this paper is to propose competent measures for the reduction of NOx emissions from marine diesel engines in order to be in compliance with the technical code alongside promoting energy efficiency and environmental sustainability in the marine sector. Based on the code’s instructions, all marine ships constructed or renovated after January the 1st of the year 2000, that are propelled by diesel engines of power output over 130 kW, are obliged to be certified by the NOx technical code and also to meet the emissions’ limit according to the Annex VI of MARPOL 73/78. To this end, recommendation for the most efficient and cost-effective resolution in relation to the studied engines is made. The findings can be applied to similar vessels that face similar levels of excess emissions
Advances in Mechanical Engineering, 2009
Taking into account the complexity and cost of a direct experimental approach, the recourse to simulation, which can also predict inaccessible information by measurement, offers an effective and fast alternative to apprehend the problem of pollutant emissions from internal combustion engines. An analytical model based on detailed chemical kinetics employed to calculate the pollutant emissions of a marine Diesel engine in general gave satisfactory results compared to experimentally measured results. Especially, the nitric oxide (NO) emission values were found to be higher than the limiting values tolerated by the International Maritime Organization (IMO). Thus, this study was undertaken to reduce to the maximum these emissions. The reduction of pollutant emissions is apprehended with exhaust gas recirculation (EGR).