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102. Experimental and numerical investigation of evaporating fuel films in combustion

Author

Jüngst, Niklas, Frapolli, Nicolò, Wright, Yuri Martin, Boulouchos, Konstantinos, and Kaiser, Sebastian A.

Abstract

Fuel films evaporating throughout combustion can cause soot formation in spark-ignited direct-injection (DI) engines. In this work, laser-induced fluorescence (LIF), combustion imaging, 3D computational fluid dynamics (CFD), and a low-dimensional model (LDM) were used to investigate fuel-film evaporation, combustion, and soot formation in an atmospheric-pressure constant-flow facility that serves as a DI model experiment. A six-hole injector laterally injects isooctane doped with toluene as a fluorescent tracer. Most of the fuel evaporates into the preheated air crossflow, but some impinges on a quartz window on the opposite side, forming fuel films. The fuel/air-mixture can be ignited by spark electrodes protruding into the chamber. LIF was used to image the fuel-film thickness at different times after start of injection (aSOI). From that, the film mass and evaporation rate are calculated. The large eddy simulation (LES) CFD employs a Lagrangian treatment for the dispersed phase in combination with models for spray/wall interaction and the wall film. CFD and LIF consistently find that evaporation rates are highest for early times aSOI and remain constant from about 10 ms aSOI. At ambient temperature the evaporation rates from LIF and CFD are almost the same while at elevated temperatures the CFD predicts about a two times higher evaporation rate than measured. LIF, CFD, and LDM reveal a strong dependence of the evaporation rate on the wall temperature, while there is very little influence of combustion and thus convective heat transfer. The simulations show that the fuel-film temperature rapidly reaches the wall temperature that remains approximately constant throughout evaporation. High-speed combustion imaging and CFD show the inception of soot pockets at similar times, close to the evaporating fuel films, and consistent in spatial extent., Applications in Energy and Combustion Science, 7, ISSN:2666352X

Published
2021

118. Investigations on spark pre-chamber ignition and subsequent turbulent jet main chamber ignition in a novel optically accessible test rig.

Author

Vera-Tudela, Walter, Barro, Christophe, and Boulouchos, Konstantinos

Abstract

Turbulent jet ignition (TJI) is a promising strategy to ignite diluted air-fuel mixtures; this is usually generated by igniting a fraction of the mixture inside a small pre-chamber. Nevertheless, the processes that take place inside the pre-chamber, as well as the injection of the turbulent jet into the main chamber and its subsequent re-ignition are not fully understood. The current work presents an experimental investigation that studies the effects of the nozzle size, turbulence level, and air-fuel mixture on the pre-chamber ignition and main chamber re-ignition and combustion. To accomplish this, a series of experiments have been carried out under different boundary conditions. To understand the phenomena taking place in the pre- and main chamber, two different approaches were taken: On one hand, (1) pressure-based diagnostics were applied by fitting a pressure sensor in each of the chambers. This was done to trace the pressure evolution during the whole combustion event and to calculate the heat-release. On the other hand, (2) optical diagnostics were setup on both combustion chambers, using dual schlieren setups synchronized at the same frame rate. The optically accessible test rig and the combination of schlieren in the pre-chamber (PC) & main-chamber (MC) allows to visualize the ignition, flame propagation, quenching mechanisms and re-ignition under a wide range of boundary conditions. This combined with the pressure traces and heat-release give a full understanding of the ignition and combustion processes. Higher turbulence levels and equivalence ratios increase the propagation of the flame front and the peak pressure in the pre-chamber. The resulting higher nozzle-exit velocities lead, on one hand, to faster mixing and therefore to a larger portion of main chamber fuel within the jet, which decrease the main chamber combustion duration. On the other hand, to high quenching and longer re-ignition times, which show the adverse effect. [ABSTRACT FROM AUTHOR]

Published
2022
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124. Multiple Cycle LES Simulations of a Direct Injection Natural Gas Engine

Author

Schmitt, Martin, Hu, Rennan, Wright, Yuri, Soltic, Patrik, Boulouchos, Konstantinos, Schmitt, Martin, Hu, Rennan, Wright, Yuri, Soltic, Patrik, and Boulouchos, Konstantinos

Abstract

In this work the flow field evolution, mixture formation and combustion process in an engine with methane Direct Injection (DI) is investigated using Large Eddy Simulations. The supersonic methane injection is modeled according to Müller et al. (2013) and combustion by a level set approach. The flame propagation showed to be dependent on the grid resolution. Higher grid resolutions have two opposing effects: first the fraction of unresolved turbulence is reduced, which decrease the flame speed and second flame wrinkling is increased resulting in faster flame propagation. For the observed setup the wrinkling effect was stronger. The average in-cylinder pressure traces as well as the cyclic variability thereof were compared to experimental data and very good agreement was found. During the supersonic gaseous injection the turbulence level in the cylinder is significantly increased, which dissipates quickly and thus has only a minor effect on the flame propagation. The introduced momentum showed a larger impact, since it enhances the tumble motion resulting in increased turbulence levels as the tumble decays shortly before ignition. During DI the cyclic differences in the tumble motion are preserved, but the impact on the average tumble level results in changing relative differences of the cyclic turbulence levels at ignition timing. Thus an injection direction supporting the tumble flows is expected to reduce the Cycle-to-Cycle Variations (CCV), while a reduction of the tumble strength could increase the CCV level. Compared to the fluctuations in the turbulence levels, the cyclic variability of the equivalence ratio at the injection location with DI showed a minor effect on the simulated CCVs.

Published
2021

129. Exhaust-stream and in-cylinder measurements and analysis of the soot emissions from a common rail diesel engine using two fuels

Author

Kirchen, Patrick, Obrecht, Peter, Boulouchos, Konstantinos, and Bertola, Andrea

Subjects
Diesel motor exhaust gas -- Environmental aspects, Diesel motor exhaust gas -- Composition, Soot -- Environmental aspects, Diesel motor -- Environmental aspects, Diesel motor -- Fuel and fuel systems, Diesel motor -- Mechanical properties, Engineering and manufacturing industries, Science and technology
Abstract

The operation and emissions of a four cylinder, passenger car common-rail diesel engine operating with two different fuels was investigated on the basis of exhaust-stream and in-cylinder soot measurements, as well as a thermodynamic analysis of the combustion process. The two fuels considered were a standard diesel fuel and a synthetic diesel (fuel two) with a lower aromatic content, evaporation temperature, and cetane number than the standard diesel. The exhaust-stream soot emissions, measured using a filter smoke number system, as well as a photo-acoustic soot sensor (AVL Micro Soot Sensor), were lower with the second fuel throughout the entire engine operating map. To elucidate the cause of the reduced exhaust-stream soot emissions, the in-cylinder soot temperature and the KL factor (proportional to concentration) were measured using miniature, three-color pyrometers mounted in the glow plug bores. Using the maximum KL factor value to quantify the soot formation process, it was seen that for all operating points, less soot was formed in the combustion chamber using the second fuel. The oxidation of the soot, however, was not strongly influenced by the fuel, as the relative oxidized soot fraction was not significantly different for the two fuels. The reduced soot formation of fuel two was attributed to the lower aromatic content of the fuel The soot cloud temperatures for operation with the two fuels were not seen differ significantly. Similar correlations between the cylinder-out soot emissions, characterized using the pyrometers, and the exhaust-stream soot emissions were seen for both fuels. The combustion process itself was only seen to differ between the two fuels to a much lesser degree than the soot formation process. The predominant differences were seen as higher maximum fuel conversion rates during premixed combustion at several operating points, when fuel two was used. This was attributed to the lower evaporation temperatures and longer ignition delays (characterized by the lower cetane number) leading to larger premixed combustion fractions. [DOI: 10.1115/1.4001083]

Published
2010

130. Reicht der Strom für die Transformation?

Author

Castiglioni, Luca, Gysler, Matthias, and Boulouchos, Konstantinos

Subjects
INFRASTRUCTURE (Economics), SYNTHETIC fuels, CARBON emissions, FREIGHT & freightage, HYDROGEN as fuel
Abstract

Copyright of Volkswirtschaft is the property of State Secretariat for Economic Affairs (SECO) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2022

136. Hydrogen-enhanced gasoline stratified combustion in SI-DI engines

Author

Conte, Enrico and Boulouchos, Konstantinos

Subjects
Internal combustion engines -- Energy use, Internal combustion engines -- Mechanical properties, Hydrogen -- Chemical properties, Hydrogen -- Thermal properties, Combustion -- Observations, Engineering and manufacturing industries, Science and technology
Abstract

Experimental investigations were carried out to assess the use of hydrogen in a gasoline direct injection (GDI) engine. Injection of small amounts of hydrogen (up to 27% on energy basis) in the intake port creates a reactive homogeneous background for the direct injection of gasoline in the cylinder. In this way, it is possible to operate the engine with high exhaust gas recirculation (EGR) rates and, in certain conditions, to delay the ignition timing as compared to standard GDI operation, in order to reduce N[O.sub.x] and HC emissions to very low levels and possibly soot emissions. The results confirmed that high EGR rates can be achieved and N[O.sub.x] and HC emissions reduced, showed significant advantage in terms of combustion efficiency and gave unexpected results relative to the delaying of ignition, which only partly confirmed the expected behavior. A realistic application would make use of hydrogen-containing reformer gas produced on board the vehicle, but safety restrictions did not allow using carbon monoxide in the test facility. Thus, pure hydrogen was used for a best-case investigation. The expected difference in the use of the two gases is briefly discussed. [DOI: 10.1115/1.2795764]

Published
2008

137. The Flex-OeCoS—a Novel Optically Accessible Test Rig for the Investigation of Advanced Combustion Processes under Engine-Like Conditions

Author

Schneider, Bruno, Schürch, Christian, Boulouchos, Konstantinos, Herzig, Stefan, Hangartner, Marc, Humair, David, Wüthrich, Silas, Gossweiler, Christoph, and Herrmann, Kai

Subjects
Fine Wire Thermocouples, Research Facilities, Experimental Apparatus, Engine Combustion, Dual Fuel, High Pressure High Temperature, Optical Access, Pressure Indication, PIV measurements, lcsh:T, lcsh:Technology
Abstract

A new test rig has been designed, built and commissioned, and is now jointly pursued to facilitate experimental investigations into advanced combustion processes (i.e., dual fuel, multi-mode) under turbulent conditions at high, engine-like temperature and pressure levels. Based on a standard diesel engine block, it offers much improved optical access to the in-cylinder processes due to its separated and rotated arrangement of the compression volume and combustion chamber, respectively. A fully variable pneumatic valve train and the appropriate preconditioning of the intake air allows it to represent a wide range of engine-like in-cylinder conditions regarding pressures, temperatures and turbulence levels. The modular design of the test rig facilitates easy optimizations of the combustion chamber/cylinder head design regarding different experimental requirements. The name of the new test rig, Flex-OeCoS, denotes its Flexibility regarding Optical engine Combustion diagnostics and/or the development of corresponding Sensing devices and applications. Measurements regarding in-cylinder gas pressures, temperatures and the flow field under typical operating conditions are presented to complete the description and assessment of the new test rig., Energies, 13 (7), ISSN:1996-1073

Published
2020

138. tji_sup – Supplemental material for Development and validation of a novel quasi-dimensional combustion model for un-scavenged prechamber gas engines with numerical simulations and engine experiments

Author

Bardis, Konstantinos, Kyrtatos, Panagiotis, Guoqing Xu, Barro, Christophe, Wright, Yuri Martin, and Boulouchos, Konstantinos

Subjects
FOS: Other engineering and technologies, 99999 Engineering not elsewhere classified
Abstract

Supplemental material, tji_sup for Development and validation of a novel quasi-dimensional combustion model for un-scavenged prechamber gas engines with numerical simulations and engine experiments by Konstantinos Bardis, Panagiotis Kyrtatos, Guoqing Xu, Christophe Barro, Yuri Martin Wright and Konstantinos Boulouchos in International Journal of Engine Research

Published
2020
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139. Estudio de evaluación económica de la inversión necesaria en Suiza para la implementación del transporte eléctrico

Author

Boulouchos, Konstantinos, Mancera Sugranes, Albert, Universitat Politècnica de València. Departamento de Máquinas y Motores Térmicos - Departament de Màquines i Motors Tèrmics, Universitat Politècnica de València. Escuela Técnica Superior de Ingenieros Industriales - Escola Tècnica Superior d'Enginyers Industrials, Belanche Guadas, Ignacio, Boulouchos, Konstantinos, Mancera Sugranes, Albert, Universitat Politècnica de València. Departamento de Máquinas y Motores Térmicos - Departament de Màquines i Motors Tèrmics, Universitat Politècnica de València. Escuela Técnica Superior de Ingenieros Industriales - Escola Tècnica Superior d'Enginyers Industrials, and Belanche Guadas, Ignacio

Abstract

[ES] Se lleva a cabo un estudio económico de la capacidad del país para suministrar la electricidad que sería necesaria tener disponible ante un escenario de electrificación total del transporte de mercancías por carretera, teniendo en cuenta las diferentes tecnologías disponibles en Suiza para la generación de electricidad, tanto costes como emisiones de cada una de ellas, y el cumplimiento del objetivo de cero emisiones netas establecido para 2050. Un estudio en el que se tendrá en cuenta la actual demanda eléctrica de Suiza, más una demanda extra supuesta debida a la necesidad de tener que cargar todos esos nuevos vehículos eléctricos. Además, para la distribución eficiente de los nuevos niveles de demanda eléctrica, será necesario la instalación de nuevos transformadores. Por otro lado, uno de los problemas principales cuando se presenta un vehículo eléctrico es su tiempo de recarga de las baterías, así como la autonomía que posee. Por lo que, en el estudio también serán incluidos tanto costes de instalación y mantenimiento de transformadores y diferentes puestos de carga por el territorio Suizo, que permitan la recarga periódica de las baterías y no tener que recargar el vehículo solamente cuando esté estacionado durante un largo periodo, [EN] To assess the impact of growing emissions, the decarbonisation of the heavy-duty freight transportation is considered. This sector of the road transport accounts for 25% of the emissions. Its electrification would have a significant influence in achieving the objective of net-zero emissions by 2050. However, the introduction of electric vehicles in the road network will cause an impact to the electricity market. This study evaluates different approaches for freight transportation full electrification and the necessary investment to accomplish it. In chapter 2, a full analysis of the Swiss energy sector is done. Then, chapter 3 makes an analysis of the Swiss freight transportation sector. Chapter 4 presents the Swiss power grid, its characteristics and the consequences to the grid of having an electric freight transportation sector. Finally, the following chapters address the methodology, results and discussion, respectively, of the required investment for electrification of the sector.

Published
2020

140. Numerische Simulation der Zündung und Verbrennung von mit Diesel pilotierten Erdgasstrahlen

Author

Boulouchos, Konstantinos (Prof. Dr.), Sattelmayer, Thomas (Prof. Dr.), Jud, Michael, Boulouchos, Konstantinos (Prof. Dr.), Sattelmayer, Thomas (Prof. Dr.), and Jud, Michael

Abstract

Die Hochdruck-Direkteinblasung von Erdgas mit Diesel-Pilotzündung hat das Potenzial, den Methanschlupf von Gasmotoren zu minimieren. Diese Arbeit verfolgt das Ziel, ein Simulationsmodell auf Basis detaillierter Chemie zur Vorhersage der Zündung und Verbrennung von Erdgasstrahlen zu entwickeln, zu validieren und anzuwenden. Die Auswahl der benötigten Reaktionskinetik erfolgt auf Basis experimenteller und numerischer Untersuchungen an einer schnellen Kompressions-Expansionsmaschine. Die Eignung des numerischen Modells zur Vorhersage der räumlichen sowie zeitlichen Interaktion von Diesel- und Gasstrahl wird anhand des Vergleichs mit experimentellen Daten nachgewiesen., High-pressure direct injection of natural gas with diesel pilot ignition has the potential to minimize the methane slip of gas engines. The aim of this work is to develop, validate and apply a simulation model based on detailed chemistry for predicting the ignition and combustion of natural gas jets. The required reaction kinetics are selected on the basis of experimental and numerical investigations on a rapid compression-expansion machine. The suitability of the numerical model for predicting the spatial and temporal interaction of diesel and gas jets is demonstrated by comparison with experimental data.

Published
2020

141. Numerische Simulation der Zündung und Verbrennung von mit Diesel pilotierten Erdgasstrahlen

Author

Sattelmayer, Thomas (Prof. Dr.), Sattelmayer, Thomas (Prof. Dr.);Boulouchos, Konstantinos (Prof. Dr.), Jud, Michael, Sattelmayer, Thomas (Prof. Dr.), Sattelmayer, Thomas (Prof. Dr.);Boulouchos, Konstantinos (Prof. Dr.), and Jud, Michael

Abstract

Die Hochdruck-Direkteinblasung von Erdgas mit Diesel-Pilotzündung hat das Potenzial, den Methanschlupf von Gasmotoren zu minimieren. Diese Arbeit verfolgt das Ziel, ein Simulationsmodell auf Basis detaillierter Chemie zur Vorhersage der Zündung und Verbrennung von Erdgasstrahlen zu entwickeln, zu validieren und anzuwenden. Die Auswahl der benötigten Reaktionskinetik erfolgt auf Basis experimenteller und numerischer Untersuchungen an einer schnellen Kompressions-Expansionsmaschine. Die Eignung des numerischen Modells zur Vorhersage der räumlichen sowie zeitlichen Interaktion von Diesel- und Gasstrahl wird anhand des Vergleichs mit experimentellen Daten nachgewiesen., High-pressure direct injection of natural gas with diesel pilot ignition has the potential to minimize the methane slip of gas engines. The aim of this work is to develop, validate and apply a simulation model based on detailed chemistry for predicting the ignition and combustion of natural gas jets. The required reaction kinetics are selected on the basis of experimental and numerical investigations on a rapid compression-expansion machine. The suitability of the numerical model for predicting the spatial and temporal interaction of diesel and gas jets is demonstrated by comparison with experimental data.

Published
2020

150. Decarbonisation of transport: options and challenges

Author

Gillett, William, Bettzüge, Marc Oliver, Blok, Kornelius, Boulouchos, Konstantinos, Bradshaw, Alexander, Bruce, Peter, Duic, Neven, Frank, Harry, Giannopoulos, George, Hamacher, Thomas, Kretzschmar, Jan, Johnsson, Filip, La Poutre, Han, Lauriko, Juhani, Oswald, Kirsten, Schmidt, Thomas Justus, Sturm, Peter-Johann, and Ulleberg, Oystein

Subjects
options for reducing greenhous gas, EU carbon emission targets, policy framework for the decarbonisastion of transport
Abstract

The focus of this report is on EU policies for the decarbonisation of passenger and freight transport, on urban and inter-urban roads in the period from 2020 to 2050, when major changes are expected to result from replacing gasoline and diesel engine vehicles with low- emission vehicles, and from the continuing growth in the use of ICT. Key issues include the need to contain growth of transport demand, the need for more low-carbon electricity generation to support the electrification of vehicle powertrains in parallel with growing demands for electricity from industry and the buildings sector, new business models for road vehicle ownership and use, and the introduction of autonomous vehicles. The report reviews and analyses the available scientific evidence relating to the management of road transport demand, mobility and traffic, as well as driver behaviour and decision-making, clean vehicle powertrains and energy carriers (fuels), the implications of coupling with the electricity sector, and the overall design and operation of road transport systems. Policies relating to other forms of transport, including rail, inland waterways, maritime and aviation, are also briefly addressed.

Published
2019

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