The SAE MOBILUS platform will continue to be accessible and populated with high quality technical content during the coronavirus (COVID-19) pandemic. x

Your Selections

Chryssakis, Christos
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Events

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Computational Investigation of In-Cylinder NOX Emissions Reduction in a Large Marine Diesel Engine Using Water Addition Strategies

National Technical Univ. of Athens-Christos Chryssakis, Lambros Kaiktsis, Athanasios Frangopoulos
Published 2010-04-12 by SAE International in United States
In the present work, the effects of water introduction in a large two-stroke marine diesel engine operating at full load are studied via Computational Fluid Dynamics, utilizing a modified version of the KIVA-3V code. The impact of two techniques, namely intake air fumigation and Direct Water Injection (DWI) on pollutant emissions and Specific Fuel Oil Consumption (SFOC) is investigated. It is concluded that DWI is more effective in reducing NOx emissions; however, its performance in terms of soot emissions and SFOC is inferior. The analysis shows that the 2016 NOx emission standards set by the International Maritime Organization, dictating an 80% reduction, could be met with water addition strategies. The present results demonstrate the potential of water addition techniques, and suggest that a substantial improvement of engine operation with optimized water addition strategies may be feasible.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Influence of Heavy Fuel Properties on Spray Atomization for Marine Diesel Engine Applications

National Technical University of Athens (NTUA)-Nikolaos Kyriakides, Christos Chryssakis, Lambros Kaiktsis
Published 2009-06-15 by SAE International in United States
In the present work, a model with the thermophysical properties of Heavy Fuel Oil, typically used in marine diesel engines, has been developed and implemented into the KIVA CFD code. The effect of fuel properties on spray atomization is investigated by performing simulations in a constant-volume high-pressure chamber, using the E-TAB and the USB breakup models. Two different nozzle sizes, representative of medium- and low-speed marine diesel engines, have been considered. The simulations have been performed for two values of chamber pressure, corresponding to operation at partial and full engine load. The results indicate that, in comparison to a diesel spray, the Heavy Fuel spray is characterized by comparable values of penetration length, and larger droplet sizes. These findings are correlated to experimental results from the literature.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Optimization of Injection Characteristics in a Large Marine Diesel Engine Using Evolutionary Algorithms

National Technical University of Athens (NTUA)-Panagiotis Andreadis, Christos Chryssakis, Lambros Kaiktsis
Published 2009-04-20 by SAE International in United States
The reduction of pollutant emissions of marine diesel engines can be achieved by employing multiple injection strategies, similar to the ones used in automotive engines. In the present work, the options for advanced injection strategies, in terms of pilot injections, are explored for a large two-stroke marine diesel engine operating at full load, by utilizing Computational Fluid Dynamics simulations coupled with an Evolutionary Algorithm. The goals of the present Multi-Objective constrained optimization are the minimization of nitrogen oxides (NOx) emissions and engine specific fuel consumption. The constraint, imposed by structural limitations of the engine, is the maximum cylinder pressure. The design variables include parameters controlling the pilot and main injections, and the injected total mass. The problem is handled as a Multi-Objective Optimization Problem, and the final set of elite solutions is identified based on the Pareto dominance. The methodology yields two families of solutions, corresponding to early and late pilot injection, providing significant improvement, both in terms of NOX emissions and engine efficiency. The elite solutions are analyzed and interpreted by detailed processing of…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Coupling of a 1-D Injection Model with a 3-D Combustion Code for Direct Injection Diesel Engine Simulations

IFP Powertrain Engineering-Julien Bohbot, Christos Chryssakis, Pierre Pacaud, Adlène Benkenida
Published 2008-04-14 by SAE International in United States
Modern diesel engines operate under injection pressures varying from 30 to 200 MPa and employ combinations of very early and conventional injection timings to achieve partially homogeneous mixtures. The variety of injection and cylinder pressures, as well as injector dynamics, result in different injection rates, depending on the conditions. These variations can be captured by 1-D injection models that take into account the dynamics of the injector, the cylinder and injection pressures, and the internal geometry of the nozzle. The information obtained by these models can be used to provide initial and boundary conditions for the spray modeling in a 3-D combustion code. In this paper, a methodology for coupling a 1-D injection model with a 3-D combustion code for direct-injected diesel engines is presented. A single-cylinder diesel engine has been used to demonstrate the capabilities of the model under varying injection conditions. Moreover, this coupling strategy opens a new methodology for 3-D calculations that do not need to fit initial conditions but use directly a 0-D model for intake/exhaust conditions and injection conditions. Using…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Simultaneous Reduction of NOX and Soot in a Heavy-Duty Diesel Engine by Instantaneous Mixing of Fuel and Water

Komatsu Ltd.-Taisuke Murotani, Kazutaka Hattori, Etsuro Sato
University of Michigan-Christos Chryssakis, Aristotelis Babajimopoulos, Dennis N. Assanis
Published 2007-04-16 by SAE International in United States
Meeting diesel engine emission standards for heavy-duty vehicles can be achieved by simultaneous injection of fuel and water. An injection system for instantaneous mixing of fuel and water in the combustion chamber has been developed by injecting water in a mixing passage located in the periphery of the fuel spray. The fuel spray is then entrained by water and hot air before it burns.The experimental work was carried out on a Rapid Compression Machine and on a Komatsu direct-injection heavy-duty diesel engine with a high pressure common rail fuel injection system. It was also supported by Computational Fluid Dynamics simulations of the injection and combustion processes in order to evaluate the effect of water vapor distribution on cylinder temperature and NOX formation. It has been concluded that when the water injection is appropriately timed, the combustion speed is slower and the cylinder temperature lower than in conventional diesel combustion. The result is drastic NOX reduction with a simultaneous decrease of soot emissions. The computational results are in agreement with experimental measurements and provide detailed information…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Simulation of a 4-Cylinder Turbocharged Gasoline Direct Injection Engine Using a Direct Temporal Coupling Between a 1D Simulation Software and a 3D Combustion Code

Institut Français du Pétrole (IFP)-Julien Bohbot, Christos Chryssakis, Marjorie Miche
Published 2006-10-16 by SAE International in United States
This paper presents a novel methodology to investigate engine behaviour using an original numerical approach based on the direct temporal coupling between IFP-ENGINE, a 1D engine simulation tool used for the simulation of the gas exchange system, and IFP-C3D, a 3D CFD code used to simulate combustion and pollutant emissions. The coupling method is used to compute steady conditions of the whole engine dynamic system but could also be applied for transient operating conditions. To demonstrate the capabilities of the model a 4-cylinder turbocharged gasoline engine is modelled at two different operating points and the comparison with experimental measurements is shown.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Development and Validation of a Comprehensive CFD Model of Diesel Spray Atomization Accounting for High Weber Numbers

Korea Advanced Institute of Science and Technology-Choongsik Bae
University of Michigan-Christos Chryssakis, Dennis N. Assanis
Published 2006-04-03 by SAE International in United States
Modern diesel engines operate under injection pressures varying from 30 to 200 MPa and employ combinations of very early and conventional injection timings to achieve partially homogeneous mixtures. The variety of injection and cylinder pressures results in droplet atomization under a wide range of Weber numbers. The high injection velocities lead to fast jet disintegration and secondary droplet atomization under shear and catastrophic breakup mechanisms. The primary atomization of the liquid jet is modeled considering the effects of both infinitesimal wave growth on the jet surface and jet turbulence. Modeling of the secondary atomization is based on a combination of a drop fragmentation analysis and a boundary layer stripping mechanism of the resulting fragments for high Weber numbers. The drop fragmentation process is predicted from instability considerations on the surface of the liquid drop. Validation of the model has been performed by comparing the computational results with experimental measurements from isolated drops in shock tube experiments as well as with observations from fully developed diesel sprays.
Annotation ability available