Browsing by Author "Imperato, Matteo"

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    Dieselmoottorien suorituskyvyn parantaminen
    (2014-04-29) Vahtila, Vesa; Imperato, Matteo; Insinööritieteiden korkeakoulu; Mikkola, Tommi
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    The engine of the future: spark ignited (SI) or compression ignited (CI)?
    (2013-11-29) Isotalo, Henri; Imperato, Matteo; Insinööritieteiden korkeakoulu; Pietola, Matti
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    Future Combustion Technology for Synthetic and Renewable Fuels in Compression Ignition Engines (REFUEL) - Final report
    (Aalto University, 2012) Aakko-Saksa, Päivi; Brink, Anders; Happonen, Matti; Heikkilä, Juha; Hulkkonen, Tuomo; Imperato, Matteo; Kaario, Ossi; Koponen, Päivi; Larmi, Martti; Lehto, Kalle; Murtonen, Timo; Sarjovaara, Teemu; Tilli, Aki; Väisänen, Esa; Energiatekniikan laitos; Department of Energy Technology; Internal Combustion Engine Research Group; Insinööritieteiden korkeakoulu; School of Engineering
    This domestic project, Future Combustion Technology for Synthetic and Renewable Fuels in Compression Ignition Engines (ReFuel), was part of a Collaborative Task "Future Combustion Technology for Synthetic and Renewable Fuels in Transport" of International Energy Agency (IEA) Combustion Agreement. This international Collaborative Task is coordinated by Finland. The three-year (2009-2011) project was a joint research project with Aalto University (Aalto), Tampere University of Technology (TUT), Technical Research Centre of Finland (VTT) and Åbo Akademi University (ÅAU). The project was funded by TEKES, Wärtsilä Oyj, Neste Oil Oyj, Agco Sisu Power, Aker Arctic Technology Oy and the research partners listed above. Modern renewable diesel fuels have excellent physical and chemical properties, in comparison to traditional crude oil based fuels. Purely paraffinic fuels do not contain aromatic compounds and they are totally sulphur free. Hydrotreated Vegetable Oil (HVO) was studied as an example of paraffinic high cetane number (CN) diesel fuels. HVO has no storage and low temperature problems like the fatty acid methyl esters (FAMEs) have. The combustion properties are better than those of crude oil based fuels and FAME, because they have very high cetane numbers and contain no polyaromatic hydrocarbons (PAH). With low HVO density, viscosity and distillation temperatures, these advantageous properties allow far more advanced combustion strategies, such as very high exhaust gas recirculation (EGR) rates or extreme Miller timings, than has been possible with current fossil fuels. The implementation of these advanced combustion technologies, together with the novel renewable diesel fuel, brought significant nitrogen oxides (NOx), particulate matter (PM) emission reductions with no efficiency losses. The objective of ReFuel project was to develop new extremely low emission combustion technologies for new renewable fuels in compression ignition engines. The target was to decrease emissions at least by 70%. The scope was to utilize the physical and chemical properties of the renewable fuels that differ from properties of the traditional crude oil based fuels and to develop optimum combustion technologies for them. The project focused firstly, on paraffinic high cetane number fuels i.e. hydrotreated vegetable oil fuel as a typical representative of this kind of fuel and secondly, on fuels with high content of oxygenates. This was implemented by blending oxygenate to HVO fuel.
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    Studies on the reduction of nitrogen oxides emission in a large-bore diesel engine
    (Aalto University, 2016) Imperato, Matteo; Sarjovaara, Teemu, Dr., Neste Corporation, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Internal Combustion Engine Technology; Insinööritieteiden korkeakoulu; School of Engineering; Larmi, Martti, Prof., Aalto University, Department of Mechanical Engineering, Finland
    This experimental research studied different technologies for reducing nitrogen oxides (NOx) in the exhaust gases, running with a large-bore medium-speed diesel research engine. NOx mainly form during combustion in local high temperature zones. This study considered primary methods, avoiding high combustion temperatures. In particular, the Miller cycle, which is a proven concept for NOx reduction, was deeply studied. This technology was applied by closing early the intake valves to create a first gas expansion before the compression stroke, thus reducing the effective compression ratio. At high load, a detailed analysis of the mixing-controlled combustion, which constitutes the most influent part of the combustion process, was carried out, reaching in-cylinder pressure of 300 bar. Same NOx level and no soot were achieved increasing the output power, while keeping the same fuel injection pressure.At partial load, a more extensive study of different Miller rates was performed. An advanced Miller rate resulted in NOx reduction up to 55%. Since the Miller cycle presented some limitations, other techniques were implemented together with the Miller cycle. First, a split injection strategy was tested with low fuel injection pressure. Then, a paraffinic fuel, hydrotreated vegetable oil (HVO), was tested, while keeping lower oxygen content in the combustion chamber, obtained by retaining a part of the exhaust gases. The results of the experiments with split injection showed that it was difficult to decrease further NOx emissions compared to the values obtained with the Miller cycle alone, but specific fuel consumption decreased when a small pilot injection was used. However, a later injection timing could be used to obtain lower NOx values with a small drawback in fuel consumption. HVO's ignitability allowed running with very advanced Miller cycle and low oxygen content. It was possible to obtain low NOx figures, but a certain increase of specific fuel consumption took place.This thesis showed that a unique tool for obtaining a significant NOx reduction without drawbacks in the whole engine load spectrum could not be found. Due to lower combustion temperatures, a higher specific fuel consumption was a common downside. Optimization of injection strategy, use of alternative fuels and dilution with inert mass are valuable tools to implement for achieving low engine-out NOx in large-bore engines. However, the investment costs the possible drawbacks must be accurately evaluated in each case.