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Calibration and Validation of a Diesel Oxidation Catalyst Model: from Synthetic Gas Testing to Driving Cycle Applications

SAE International Journal of Engines

Aristotle Univ. Thessaloniki-Grigorios Koltsakis, Zissis Samaras
Exothermia S.A.-Maria Kalogirou
  • Journal Article
  • 2011-01-1244
Published 2011-04-12 by SAE International in United States
To meet future stringent emission regulations such as Euro6, the design and control of diesel exhaust after-treatment systems will become more complex in order to ensure their optimum operation over time. Moreover, because of the strong pressure for CO₂ emissions reduction, the average exhaust temperature is expected to decrease, posing significant challenges on exhaust after-treatment. Diesel Oxidation Catalysts (DOCs) are already widely used to reduce CO and hydrocarbons (HC) from diesel engine emissions. In addition, DOC is also used to control the NO₂/NOx ratio and to generate the exothermic reactions necessary for the thermal regeneration of Diesel Particulate Filter (DPF) and NOx Storage and Reduction catalysts (NSR). The expected temperature decrease of diesel exhaust will adversely affect the CO and unburned hydrocarbons (UHC) conversion efficiency of the catalysts. Therefore, the development cost for the design and control of new DOCs is increasing. To select the best quality product at affordable price, the authors have evaluated exhaust simulation as an additional development tool.In this study, a multidimensional exhaust modeling tool based on physical background was used.…
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Exhaust Particle Sensor for OBD Application

Aristotle Univ. Thessaloniki-Leonidas Ntziachristos, Pavlos Fragkiadoulakis, Zissis Samaras
Pegasor Oy-Kauko Janka, Juha Tikkanen
Published 2011-04-12 by SAE International in United States
Efforts to develop a sensor for on-board diagnostics (OBD) of diesel vehicles are intensive as diesel particulate filters (DPFs) have become widespread around the world. This study presents a novel sensor that has been successfully tested for OBD diagnosis of damaged DPFs. The sensor is based on the "escaping current" technique. Based on this, a sample of exhaust gas is charged by a corona-ionized flow and is pumped by an ejector dilutor built in the sensor's construction. While the majority of ions return to the grounded sensor's body, a small quantity is lost with the charged particles exiting the sensor. This "escaping current" is a measurement of the particle concentration in the exhaust gas. Such a sensor has been developed and tested in real-exhaust of a diesel car and a diesel engine. The sensor provides high resolution (1 Hz, 0.3 s response time) and high sensitivity superseding OBD requirements. The sensor was used on an engine to monitor the efficiency of damaged DPFs. The signal was found to perform similar to the smokemeter, a widespread…
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Implications of Engine Start-Stop on After-Treatment Operation

SAE International Journal of Engines

Aristotle Univ. Thessaloniki-Grigorios C. Koltsakis, Zissis Samaras, Apostolos Karvountzis-Kontakiotis, Theodora Zacharopoulou
Exothermia SA-Onoufrios Haralampous
  • Journal Article
  • 2011-01-1243
Published 2011-04-12 by SAE International in United States
It is commonly accepted that future powertrains will be based to a large extent on hybrid architectures, in order to optimize fuel efficiency and reduce CO₂ emissions. Hybrid operation is typically achieved with frequent engine start-and-stops during real-world as well as during the legislated driving cycles. The cooling of the exhaust system during engine stop may pose problems if the substrate temperature drops below the light-off temperature. Therefore, the design and thermal management of after-treatment systems for hybrid applications should consider the 3-dimensional heat transfer problem carefully. On the other hand, the after-treatment system calculation in the concept design phase is closely linked with engine calibration, taking into account the hybridization strategy. Therefore, there is a strong need to couple engine simulation with 3d aftertreatment predictions.In this paper, we perform measurements in flow-through catalytic substrates and wall-flow DPF systems to monitor the thermal losses after engine shut-off. In parallel, we use an existing 3-dimensional modeling platform (axisuite®/Exothermia SA), which is enhanced with a heat transfer submodel to account for free convection and radiation from the…
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A Modeling and Experimental Investigation on an Innovative Substrate for DPF Applications

Aristotle Univ. Thessaloniki-G.C. Koltsakis, Z.C. Samaras
Auto Filter Technology GmbH-T. Wolff
Published 2010-04-12 by SAE International in United States
XP-SiC is an innovative type of a porous substrate material on the basis of a reaction formed SiC for DPF applications. The high porosity, large pore size inside the cell wall and low specific weight are the special characteristics of this substrate. The aim of the current paper is to present an investigation based on the experimental and modeling approaches to evaluate the back pressure, filtration efficiency and the thermal durability. The latter one was assessed by measuring and predicting the temperature field, as well as calculating the thermal stresses. For this purpose the filter was modeled in the commercial computational code axitrap as a stand-alone tool, in which the conservation equations of mass continuity, momentum, energy and species were solved. The soot filtrations, loading as well as the regeneration by fuel-borne catalyst were modeled. The microstructure properties of the filter and the chemistry parameters for the fuel-borne catalyst were calibrated against engine test bench data. On the engine test bench, the regeneration behavior was determined by loading the filter to different amount of initial…
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