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A Model Based Definition of a Reference CO2 Emissions Value for Passenger Cars under Real World Conditions

Aristotle University of Thessaloniki-Zissis Samaras, Dimitris Tsokolis, Athanasios Dimaratos, Leonidas Ntziachristos, Stylianos Doulgeris
TNO Automotive-Norbert Ligterink, Willar Vonk, Rob Cuelenaere
Published 2018-05-30 by SAE International in United States
With the adoption of the Worldwide harmonized Light Vehicles Test Procedure (WLTP) and the Real Driving Emissions (RDE) regulations for testing and monitoring the vehicle pollutant emissions, as well as CO2 and fuel consumption, the gap between real world and type approval performances is expected to decrease to a large extent. With respect to CO2, however, WLTP is not expected to fully eliminate the reported 40% discrepancy between real world and type approval values. This is mainly attributed to the fact that laboratory tests take place under average controlled conditions that do not fully replicate the environmental and traffic conditions experienced over daily driving across Europe. In addition, any uncertainties of a pre-defined test protocol and the vehicle operation can be optimized to lower the CO2 emissions of the type approval test.Such issues can be minimized in principle with the adoption of a real-world test for fuel consumption. However, repeatability and an accuracy of a few gCO2/km is difficult to achieve due to the actual drag, the road surface effect on driving resistance, the road…
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Experimental Investigation of Cyclic Variability on Combustion and Emissions of a High-Speed SI Engine

Aristotle University of Thessaloniki-Apostolos Karvountzis-Kontakiotis, Leonidas Ntziachristos, Zissis Samaras, Athanasios Dimaratos
Cambustion Ltd-Mark Peckham
Published 2015-04-14 by SAE International in United States
Cyclic combustion variability (CCV) is an undesirable characteristic of spark ignition (SI) engines, and originates from variations in gas motion and turbulence, as well as from differences in mixture composition and homogeneity in each cycle. In this work, the cycle to cycle variability on combustion and emissions is experimentally investigated on a high-speed, port fuel injected, spark ignition engine. Fast response analyzers were placed at the exhaust manifold, directly downstream of the exhaust valve of one cylinder, for the determination of the cycle-resolved carbon monoxide (CO) and nitric oxide (NO) emissions. A piezoelectric transducer, integrated in the spark-plug, was also used for cylinder pressure measurement. The impact of engine operating parameters, namely engine speed, load, equivalence ratio and ignition timing on combustion and emissions variability, was evaluated. The variations in mixture stoichiometry were found to have a strong effect on engine combustion variability. Rich cyclic mixture compositions exhibit lower coefficient of variation (COV) for the indicated mean effective pressure (IMEP) and NO emissions (COVNO) compared with lean mixtures. The mean value of CO emission was…
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Evaluating Particulate Emissions from a Flexible Fuel Vehicle with Direct Injection when Operated on Ethanol and Iso-butanol Blends

Aristotle University of Thessaloniki-Leonidas Ntziachristos, Stavros Amanatidis
Instrumentation and Control Systems-Alexander Bergmann
Published 2014-10-13 by SAE International in United States
The relationship between ethanol and iso-butanol fuel concentrations and vehicle particulate matter emissions was investigated. This study utilized a gasoline direct injection (GDI) flexible fuel vehicle (FFV) with wall-guided fueling system tested with four fuels, including E10, E51, E83, and an iso-butanol blend at a proportion of 55% by volume. Emission measurements were conducted over the Federal Test Procedure (FTP) driving cycle on a chassis dynamometer with an emphasis on the physical and chemical characterization of particulate matter (PM) emissions. The results indicated that the addition of higher ethanol blends and the iso-butanol blend resulted in large reductions in PM mass, soot, and total and solid particle number emissions. PM emissions for the baseline E10 fuel were characterized by a higher fraction of elemental carbon (EC), whereas the PM emissions for the higher ethanol blends were more organic carbon (OC) in nature. The higher ethanol blends and the iso-butanol blend showed lower concentrations of accumulation mode particles and size distributions shifted to smaller particle sizes compared to E10. In addition, the majority of trace elements…
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Use of a PPS Sensor in Evaluating the Impact of Fuel Efficiency Improvement Technologies on the Particle Emissions of a Euro 5 Diesel Car

Aristotle University of Thessaloniki-Stavros Amanatidis, Leonidas Ntziachristos, Zissis Samaras
EMISIA SA-Chariton Kouridis
Published 2014-04-01 by SAE International in United States
The effect of “Start & Stop” and “Gear Shift Indicator” - two widespread fuel saving technologies - on fuel consumption and particle emissions of a Euro 5 passenger car is evaluated in this paper. The vehicle was subjected to a series of different driving cycles, including the current (NEDC) and future (WLTC) cycles implemented in the European type approval procedure at cold and hot start condition and particle number was measured with an AVL Particle Counter. In addition, we have utilized two Pegasor Particle Sensor units positioned in different locations along the sampling line to assess the impact of the sampling location on the particle characteristics measured during highly transient events.The results showed that the particle number emission levels over the WLTC were comparable to the NEDC ones, whereas NOx emissions were more than twofold higher. Both fuel saving technologies can lead to reduced fuel consumption and, subsequently CO2 emissions, in the order of 5%. However, their impact on particle emissions was not straightforward, as the impact of the DPF loading was found much more…
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Applicability of the Pegasor Particle Sensor to Measure Particle Number, Mass and PM Emissions

Aristotle University of Thessaloniki-Stavros Amanatidis, Leonidas Ntziachristos, Zissis Samaras
Pegasor Oy-Kauko Janka, Juha Tikkanen
Published 2013-09-08 by SAE International in United States
The Pegasor Particle Sensor (PPS) has been earlier presented by Ntziachristos et al. (SAE Paper 2011-01-0626) as a novel small and robust instrument that can be directly installed in the exhaust line to measure exhaust particles without any dilution. The instrument is based on the electrical detection of aerosol. It is increasingly being used to measure exhaust particles from engines and vehicles with different exhaust configurations. In this study, a number of tests have been conducted using two sensors in parallel, one directly installed in the tailpipe and one installed in the CVS, side by side to the PM sampling filter. Aim of the study was to make recommendations on the proper use of the sensor and to check how the sensor signal compares to particulate mass, soot concentration, and particle number. A first finding is that external heating has to be provided to the sensor to avoid condensation. Second, very good linearity of the sensor signal is established for all three particle concentrations examined. The only exception was PM at very low concentrations, where…
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Application of the Pegasor Particle Sensor for the Measurement of Mass and Particle Number Emissions

SAE International Journal of Fuels and Lubricants

Aristotle University of Thessaloniki-Leonidas Ntziachristos, Stavros Amanatidis, Zissis Samaras
Pegasor Oy-Kauko Janka, Juha Tikkanen
  • Journal Article
  • 2013-01-1561
Published 2013-04-08 by SAE International in United States
The Pegasor Particle Sensor (PPS) is a small and lightweight sensor that can be used directly in raw exhaust to provide the mass and number concentration of exhaust aerosol. Its operation principle is based on the electrical charging of exhaust aerosol and determination of particle concentration by measuring the charge accumulated on the particles. In this paper we have applied the PPS in a variety of vehicle exhaust configurations to evaluate its performance characteristics. First, the output signal of the instrument was calibrated with diesel exhaust to deliver either the mass or the number concentration of exhaust aerosol. Linear response with the soot mass concentration measured by a Photo Acoustic Soot Sensor and number concentration measured by an Electrical Low Pressure Impactor was established. Based on this calibration, the instrument was then used to measure particle concentrations at levels produced by a gasoline direct injection vehicle and diesel exhaust filtered by particle filters of variable efficiency. Hence, the complete range of concentrations and particle characteristics typically encountered in automotive exhaust has been examined. The results…
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Use of a Catalytic Stripper as an Alternative to the Original PMP Measurement Protocol

SAE International Journal of Fuels and Lubricants

AVL LIST GmbH-Barouch Giechaskiel, Alexander Bergmann
Aristotle University of Thessaloniki-Leonidas Ntziachristos, Stavros Amanatidis, Zissis Samaras
  • Journal Article
  • 2013-01-1563
Published 2013-04-08 by SAE International in United States
The Particle Measurement Programme (PMP) developed an exhaust particle number measurement protocol that has been adopted by current light duty vehicle emission regulations in Europe. This includes thermal treatment of the exhaust aerosol to isolate solid particles only and a number counting device with a lower cutpoint of 23 nm to avoid measurement of smaller particles that may affect the repeatability of the measurement. In this paper, we examine a potential alternative to the PMP system, where the thermal treatment is replaced by a catalytic stripper (CS). This offers oxidation and not just evaporation of the volatile components. Alternative sampling systems, either fulfilling the PMP recommendations or utilizing a CS, have been explored in terms of their volatile particle removal efficiency. Tests have been conducted on diesel exhaust, diesel equipped with DPF and gasoline direct injection emissions. The results showed that the CS offers similar performance characteristics to the PMP when tested on diesel exhaust. In tests with the gasoline vehicle, the CS has been shown of leading to lower particle concentrations than the PMP,…
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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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Evaluation of Biodiesel Blends on the Performance and Emissions of a Common-Rail Light-Duty Engine and Vehicle

Laboratory of Applied Thermodynamics, Aristotle University Thessaloniki, Greece-Marina Kousoulidou, Georgios Fontaras, Leonidas Ntziachristos, Zissis Samaras
Published 2009-04-20 by SAE International in United States
Today most of the European member states offer diesel fuel which contains fatty acid methylesters (biodiesel) at a range between 0.5 to 5% vol. In order to meet longer term objectives, the mixing ratio is expected to rise up to 10% vol. in the years to come. The question therefore arises, how current engine technologies, which were not originally designed to operate on biodiesel blends, perform at this relatively high mixing ratio. A number of experiments were therefore performed over several steady-state operation modes, using a 10% vol. biodiesel blend (palm oil feedstock) on a light-duty common-rail Euro 3 engine. The experiments included measurement of the in-cylinder pressure during combustion, regulated pollutants emissions and fuel consumption. The analysis showed that the blends tested present good fuel characteristics. Combustion effects were limited but changes in the start of ignition and heat release rate could still be identified. The palm-oil biodiesel resulted in both higher and lower smoke and NOx emissions over the engine map, depending on the operation point. This was attributed to effects of both…
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A New Constant Dilution Ratio Concept for Vehicle and Engine Exhaust Particle Sampling

SAE International Journal of Engines

University Thessaloniki, Greece-Leonidas Ntziachristos, Theodoros Tzamkiozis, Athanasios Mamakos, Zissis Samaras
  • Journal Article
  • 2008-01-0762
Published 2008-04-14 by SAE International in United States
This paper presents a new concept of a partial flow sampling system (PFSS), involving a two-stage dilutor which operates at underpressure, while exhaust is sampled through a capillary. The sample flowrate is in the order of few cubic centimeters per minute. Due to the low flowrate, no tight fixation is required between the exhaust line and the capillary inlet. The dilutor may sample from an opening in the exhaust line which freely exhausts to ambient pressure. As a result, the PFSS operates at constant pressure conditions even upstream of diesel particle filters (DPF). A straightforward mathematical model is then developed to calculate the dilution ratio (DR), depending on the dilution air flowrate and the dilutor underpressure. The model is validated using CO2 as a trace gas, and a very good agreement is demonstrated between the calculated and the measured DR values. After validation, the PFSS is combined with electrical aerosol detection devices to measure the exhaust particle concentration of a diesel engine operating at different steady-state modes. Also, the filtration efficiency of two particle filters…
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