Papers by Thanos Megaritis
Processes, Nov 1, 2022
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Fuel, Oct 1, 2022
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Energies, May 27, 2023
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Energy, Aug 1, 2019
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ACS Omega
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SAE technical paper series, Jun 23, 2008
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Day 3 Wed, May 03, 2023
This paper analyzes the benefits of employing reciprocating engines to power offshore oil and gas... more This paper analyzes the benefits of employing reciprocating engines to power offshore oil and gas (O&G) loads using methanol as fuel instead of (or mixing with) diesel that has been used conventionally. The study is carried out on a methanol-based single-cylinder, 50-liter, heavy-duty reciprocating engine for two test cases of power (30 kW and 111 kW) at different boost pressure and injection timing. In this investigation, 1-dimensional modeling and analysis using Ricardo Wave software was performed. Then, the effect of adding small amounts (<10%) of hydrogen into the engine in terms of performance improvement and emissions’ reduction is explored. Moreover, engine performance, indicated thermal efficiency, and CO/NOx emissions are compared for different boost pressure values at varied injection timing and constant power. The tests are carried out by modeling multiple use cases and comparing them, including (i) direct injection of methanol, and (ii) direct injection of methanol wi...
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International Journal of Hydrogen Energy
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Soot particles are noxious emissions that are associated with global warming and are known to be ... more Soot particles are noxious emissions that are associated with global warming and are known to be harmful to humans. They are partly produced from the combustion of hydrocarbon fuels, and can be reduced by altering the fuel structure. For this, adding an oxygen moiety becomes an attractive solution to simultaneously reduce the soot formation and to enhance its oxidation. Nonetheless, the oxygenated fuel must meet several criteria to be a candidate to replace or to blend with diesel in the current engine infrastructure. For example, it must have similar physical properties and a similar energy content to diesel. One of the promising fuels that could meet these criteria is octanal. However, data on its spraying and combustion characteristics are not known, and neither fundamental studies nor studies under engine-like conditions are available in the literature to characterise the spray combustion of octanal. To fully characterise the potential of an oxygenated fuel and its sooting prope...
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Volume 1: Applied Mechanics; Automotive Systems; Biomedical Biotechnology Engineering; Computational Mechanics; Design; Digital Manufacturing; Education; Marine and Aerospace Applications, 2014
This study investigates the effect of combustion phase (premixed and diffusion phases) duration o... more This study investigates the effect of combustion phase (premixed and diffusion phases) duration on the emissions emitted from a high speed direct injection (HSDI) diesel engine fueled with neat (100%) rapeseed methyl ester (RME) and run at a constant speed (1500 rpm) with single injection strategy at constant fuel injection pressure (800 bar) and varying fuel injection timings (−12,−9,−6,−3,0) ATDC, for two loads (2.5 and 5 bars) BMEP. The obtained results were compared with those obtained when the engine run at the same conditions but with ultra-low sulfur diesel fuel (ULSD). In-cylinder pressure was measured and analyzed using (LABVIWE) program. calculation program specially written in (MATLAB) software was used to extract the apparent heat release rate, the ignition delay, combustion duration and specify the amount of heat released during the premixed and diffusion combustion phases (premixed burn fraction PMBF) and (diffusion burn fraction DBF). Emission measurements included; N...
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Urea-based selective catalytic reduction (SCR) system is widely used to reduce NOx emission from ... more Urea-based selective catalytic reduction (SCR) system is widely used to reduce NOx emission from diesel engines. The NOx conversion efficiency, as well as the adverse effects of wall-wetting is mainly influenced by the atomization characteristics of urea water solution (UWS). Under extreme winter conditions, the UWS can reach temperatures as close as its freezing temperatures. Under these adverse weather conditions the flow and spray characteristics of UWS are not well defined. In order to gain an understanding of these factors, an attempt has been made in this work to study the effect of varying the temperatures of UWS to evaluate the spray characteristics of UWS used in SCR systems. In this work, the temperatures of UWS were varied from 20°C to -10°C to consider the variations in the ambient temperatures from normal up to freezing point of UWS. Effect of temperature of UWS was significant at lower gauge pressures (ΔP) of the atomizing air. Bag breakup was observed at 20 0 C and ΔP...
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An attempt has been made to study the combustion and emission characteristics of ultra-low diesel... more An attempt has been made to study the combustion and emission characteristics of ultra-low diesel fuel for high speed direct injection ( HSDI) diesel engine at different fuel injection timings( -12,-9,-6,-3,0 )ATDC . The fuel injection pressure was 800 bar and at high load ( 80Nm= 5BMAP) , low load ( 40Nm=2.5BMAP ) , With constant engine speed ( 1500rpm) . In-cylinder pressure was measured and then analyzes this pressure using LABVIWE program and calculation program in MATLAB software to extract the apparent heat release rate, the ignition delay, combustion duration and the amount of heat released during the premixed and diffusion combustion phases . The influence of injection timing on the exhaust emissions such as carbon monoxide (CO), total hydrocarbons (THCs), nitric oxides (NOx), smoke number (SN) and fuel consumption were also investigated. A result referring to that the retardation of the injection timing lead to increase the ignition delay and therefore the premixed burn fra...
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Energy & Fuels, 2005
... In the present study, the particulate emissions of the diesel−hydrogen fueled engine were stu... more ... In the present study, the particulate emissions of the diesel−hydrogen fueled engine were studied using an ... in terms of mass %) is as follows: 41% carbon (soot), 14% sulfate and water, 13% ash ...fuel reforming of diesel fuel as well as of alternative fuels (ie, biodiesel, bioethanol). ...
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Energy, 2021
Abstract An experimental study was performed to explore the effect of pilot and main injection st... more Abstract An experimental study was performed to explore the effect of pilot and main injection strategy on injection interactions and the spray characteristics of biodiesels that were derived from different feedstocks. Biodiesel considered in this investigation ranged from rapeseed methyl ester, sunflower oil methyl ester, coconut oil methyl ester, waste cooking methyl ester, and tallow methyl ester. The sprays of these biodiesel were characterized through the measurement of macroscopic parameters such as spray penetration, spray angle and spray area, which were compared against ULSD for both pilot and main injection. This investigation was performed in a constant volume chamber maintained under non-reactive conditions. The magnitude of cone angle and spray area for most biodiesel were lower than ULSD. Conversely, the spray tip penetrations for most biodiesels were higher than ULSD. The main injection showed relatively larger magnitude for all macroscopic spray parameters than those of pilot injection. Expulsion of liquid was observed in the dwell period between pilot and main injection as well as end of main injection for all fuels. The end-of-injection expulsions are mainly due to injector needle dynamics rather than variation in physical properties of fuels.
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International Journal of Multiphase Flow, 2020
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IEEE Access, 2019
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Fuel, 2019
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SSRN Electronic Journal
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Fuel, 2021
NOx conversion efficiency of urea-selective-catalytic reduction (SCR) systems are governed by dis... more NOx conversion efficiency of urea-selective-catalytic reduction (SCR) systems are governed by dispersion of urea-water-solution (UWS) injected in exhaust manifold. Impingement of larger size urea droplets on mixture distribution fans as well as to the internal surfaces of SCR systems will lead to formation of deposits, which has potential to deteriorate the effectiveness of urea-SCR system. In this work, detailed analyses on droplet-wall interactions of UWS droplets impinging on a hot plate under urea-SCR-relevant conditions have been presented. The effect of lowering surface tension of UWS on droplet morphology and impact dynamics were also explored. The surface tension of UWS was lowered from 73.7 to 30.2 mN/m by adding a surfactant (DDA75). Distinct modes of droplet impact viz., deposition, thermal atomization, rebound and breakup were identified. The DDA75 droplets showed a significant increase in maximum spreading factor ( β max ) by 37% due to 59% reduction in surface tension....
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Papers by Thanos Megaritis