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Hybridization offers great potential for decreasing pollutant and carbon dioxide emissions of diesel cars. However, an assessment of the real-world emissions performance of modern diesel hybrids is missing. Here, we test three... more
Hybridization offers great potential for decreasing pollutant and carbon dioxide emissions of diesel cars. However, an assessment of the real-world emissions performance of modern diesel hybrids is missing. Here, we test three diesel-hybrid cars on the road and benchmark our findings with two cars against tests on the chassis dynamometer and model simulations. The pollutant emissions of the two cars tested on the chassis dynamometer were in compliance with the relevant Euro standards over the New European Driving Cycle and Worldwide harmonized Light vehicles Test Procedure. On the road, all three diesel-hybrids exceeded the regulatory NOx limits (average exceedance for all trips: +150% for the Volvo, +510% for the Peugeot, and +550% for the Mercedes-Benz) and also showed elevated on-road CO2 emissions (average exceedance of certification values: +178, +77, and +52%, respectively). These findings point to a wide discrepancy between certified and on-road CO2 and suggest that hybridiza...
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Airborne urban particulate and gaseous pollutants measurements were conducted at the kerbside of a busy road and at a nearby urban background site of Thessaloniki, Greece, during a winter and a summer period. The main objective was to... more
Airborne urban particulate and gaseous pollutants measurements were conducted at the kerbside of a busy road and at a nearby urban background site of Thessaloniki, Greece, during a winter and a summer period. The main objective was to observe how the financial crisis has affected the air quality in the city, compared to previous measurements. Compared to a study conducted in 2006, the current work suggests that although average concentrations at the traffic affected site remain higher that in the urban background station, the differences are much smaller than in the past. A number of observations suggest a scenario of decrease in traffic activity and increase in biomass burning for residential heating. On this basis, the results suggest that traffic may be less important as an air quality contributor in a financially hit city. On the contrary, domestic heating appears as a significant contributor and affects areas of the city that were earlier not being of environmental concern. Because of the impact of biomass burning in residential areas, exposure calculations are required to estimate whether traffic or biomass burning is the overall highest contributors to daily PM dosages that citizens of the city are exposed to.
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We present an overview of the modelling of particle number concentrations (PNC's) in five major European cities, namely Helsinki, Oslo, London, Rotterdam and Athens, in 2008. Novel emission inventories of particle numbers have been... more
We present an overview of the modelling of particle number concentrations (PNC's) in five major European cities, namely Helsinki, Oslo, London, Rotterdam and Athens, in 2008. Novel emission inventories of particle numbers have been compiled both on urban and European scales. We use atmospheric dispersion modelling for PNC's in the five target cities and on a European scale, and evaluate the predicted results against available measured concentrations. The concentrations of PN in the selected cities were mostly influenced by the emissions originated from local vehicular traffic; however, in some of the cities, also harbour and airport activities were significant. The highest values of the predicted PNC's were higher in the megacities, London and Athens, and also in Rotterdam, whereas these were lower in Helsinki and Oslo. It was numerically evaluated that the influence of coagulation and dry deposition on the predicted PNC's was substantial for urban background in Oslo...
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ABSTRACT This paper reviews the state of liquid biofuels in Greece and presents the current situation in production and research. The first part presents the production potential in terms of cultivated crops along with the industrial... more
ABSTRACT This paper reviews the state of liquid biofuels in Greece and presents the current situation in production and research. The first part presents the production potential in terms of cultivated crops along with the industrial activity on biofuels and their distribution in the country. In the second part, the research activities are discussed. It is shown that the Greek biofuel potential is significant, although some problems in the allocation of the fuel resulted in severe constraints to efficiency. Research on the optimization of biodiesel properties and on the development of 2nd generation biofuels as well on the assessment of their impacts on engine performance and emissions is remarkable and promising.
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Research Interests: Engineering, Environmental Monitoring, Air pollution, Automotive Engineering, Environmental Sciences, and 13 moreEurope, Dynamometer, Vehicle Emissions, Measurement, Specification Tests, MEASUREMENTS, Exhaust emissions, Time Factors, Ambient Temperature, Gasoline, Exhaust Gases, Motor vehicles act, and Air Pollutants
Research Interests: Environmental Engineering, Mechanical Engineering, Environmental Science, Chemistry, Ecotoxicology, and 15 moreEnvironmental Monitoring, Energy and Environment, Environmental Pollution, Medicine, Multidisciplinary, Emission reduction, Light, Environmental Impact, Diesel Fuel, Exhaust emissions, Environmental, Environment, Motor vehicles act, Air Pollutants, and Aliivibrio fischeri
Research Interests: Environmental Engineering, Mechanical Engineering, Environmental Science, Chemistry, Energy and Environment, and 11 moreAtmospheric sciences, Nucleation, Airborne Particulates, Particle, Surface Area, Particulate Matter, Condensation, Sulphuric Acid, Particle Size Distribution, Mass Balance, and Atmospheric Environment
Transport activities contribute significantly to air pollutant emissions in Europe and the impact on emissions is a key element in the evaluation of any transport policy or plan. Calculation of emissions has therefore gained institutional... more
Transport activities contribute significantly to air pollutant emissions in Europe and the impact on emissions is a key element in the evaluation of any transport policy or plan. Calculation of emissions has therefore gained institutional importance in the European Community, particularly with the development of the CAFÉ (EC, 2005a) and ECCP (EC, 2005b) programmes. Reliable and credible emission estimates are a central prerequisite, but comparisons of the results from emission models such as COPERT (Ntziachristos & ...
The demand for fossil fuel in the transport sector is constantly increasing and transportation is ranked amongst the highest greenhouse emitting sectors globally. Today, tackling CO 2 emissions from road transport a widely discussed topic... more
The demand for fossil fuel in the transport sector is constantly increasing and transportation is ranked amongst the highest greenhouse emitting sectors globally. Today, tackling CO 2 emissions from road transport a widely discussed topic and constitutes a milestone towards reaching a sustainable, carbon neutral economy. This challenge is being described in various initiatives adopted in the European Union and other parts of the world. So far several measures have been proposed and adopted for reversing the increasing greenhouse gas emissions trends. This paper attempts an overview of the existing policy framework in various countries focusing on European Union. In addition, the main technical measures proposed and promoted in this direction are presented and evaluated with respect to their greenhouse reduction potential. Special attention is paid to emerging technologies, such as hybrid vehicles and biofuels. The main factors differentiating the officially reported CO 2 emissions f...
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To meet the upcoming CO2 reduction challenges, the further electrification of vehicle powertrains is indispensable. In combination with the post-Euro 6 requirements for criteria pollutants, the exhaust system is expected to be more... more
To meet the upcoming CO2 reduction challenges, the further electrification of vehicle powertrains is indispensable. In combination with the post-Euro 6 requirements for criteria pollutants, the exhaust system is expected to be more complex to allow for extremely low emissions under all driving conditions, potentially involving technologies such as electrical heating and phase-change materials. The longer ‘zero-flow’ operation of the exhaust system in hybrid applications and the associated light-out risk have demanding accuracy requirements for heat loss calculations and require additional thermal management strategies. This paper discusses the additional challenges posed with regard to catalyst modeling in the boundary conditions of electrified vehicles and the necessary improvements that go beyond the state-of-the-art techniques. Most of the necessary improvements are linked to advanced 3D modeling of the exhaust system components accounting for free convection and radiative heat t...
Research Interests: Catalysts and Powertrain
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ABSTRACT The successful design and especially the control of the SCR system is a challenging process that can be supported by the application of simulation tools. As a first step, we employ physico-chemically informed ‘off-line’ models... more
ABSTRACT The successful design and especially the control of the SCR system is a challenging process that can be supported by the application of simulation tools. As a first step, we employ physico-chemically informed ‘off-line’ models that are calibrated with the help of targeted small- and full-scale tests. Despite their high level of sophistication, this SCR model is able to be integrated in a control-oriented simulation software platform and connected to other powertrain simulation blocks. The target is to use this simulation platform as a virtual environment for the development and optimization of SCR control strategies. The above process is demonstrated in the case of a passenger car SCR. The model is calibrated at both fresh and aged catalyst condition and validated using experimental data from the engine bench under a wide variety of operating conditions. Next, the calibrated model was coupled with embedded control models, developed for Euro 6 passenger car powertrains. The final simulation platform enabled the precalibration and optimization of dosing control strategies, saving significant experimental effort and costs. Finally, it allowed the realization of the sensitivity analysis of the embedded control strategies, a procedure which guaranties the controlled system's robustness to engine dispersion and drift.
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In the first part of this study, an improved model for the calculation of pressure drop in particulate filters was presented with special emphasis on the soot permeability properties and its dependence on temperature and pressure. With... more
In the first part of this study, an improved model for the calculation of pressure drop in particulate filters was presented with special emphasis on the soot permeability properties and its dependence on temperature and pressure. With the assumption of uniform wall flow distribution throughout the channel length, it was also possible to derive an analytical expression that was validated against experimental data on an engine bench. Using the results of pressure drop modelling, it is possible to carry out ‘inverse’ calculations of the soot mass in the filter based on the measurements of flowrate, temperature and backpressure, which forms the main subject of the present work. This approach is tested successfully against experimental data in filters of different geometry and material, yielding promising results. Such computations may be very helpful for the interpretation of experimental results in engine testing. In this paper, typical applications in the field of reaction rate asses...
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Research Interests: Chemistry, Air Quality, Biodiesel, Environmental Monitoring, Environmental Pollution, and 15 moreMedicine, Automobiles, Biofuels, Biofuel, Environmental degradation, Environmental Impact, Diesel Fuel, Ketone, Feedstock, Elsevier, Health Effect, Carcinogen, Low molecular weight, Air Pollutants, and Carbonyl compound
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Transportation is one of the major global consumers of energy, currently representing 20% of aggregate energy consumption and CO 2 emissions. Strong growth in energy consumption to 2050 is projected in all sectors, with the transport... more
Transportation is one of the major global consumers of energy, currently representing 20% of aggregate energy consumption and CO 2 emissions. Strong growth in energy consumption to 2050 is projected in all sectors, with the transport proportion projected to remain stable up to 2050. In parallel, energy consumed by transportation results in numerous pressures: on human health, on the environment, and on the planet. Several measures have been taken to reduce these pressures. As a result, air pollution induced by transportation has been significantly reduced, although the effect on planet (greenhouse effect) is a remaining issue to be addressed.
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Portable Emissions Measurement Systems (PEMS) are a valuable source of real-world operation data to support the development and validation of vehicle emission factors. For the purposes of our research, a Euro 5 compliant diesel passenger... more
Portable Emissions Measurement Systems (PEMS) are a valuable source of real-world operation data to support the development and validation of vehicle emission factors. For the purposes of our research, a Euro 5 compliant diesel passenger car equipped with a particulate filter was fitted with a PEMS system and subsequently driven over predefined driving routes designed to include a variety of driving conditions. The exhaust flow and the concentration of exhaust pollutants at the tailpipe were recorded on a second-by-second basis. Engine speed, torque and other data readings provided by the ECU of the test vehicle were also recorded, along with GPS position and vehicle-mounted weather station data. The resulting data logs were run through a Matlab-based model (CEMOD) that performs a correction of the signal from the PEMS analyzers to account for instrument time lag and response characteristics. These synchronized emission data are then used to develop engine emission maps. The use of ...
The objective of this study was to test the potential for NO emissions improvements on a typical Euro 6 diesel vehicle, following modifications to its emissions control system, under Real Drive Emissions (RDE) testing conditions. A... more
The objective of this study was to test the potential for NO emissions improvements on a typical Euro 6 diesel vehicle, following modifications to its emissions control system, under Real Drive Emissions (RDE) testing conditions. A commercially available car was selected and was first measured in its original configuration according to RDE on the road and an initial conformity factor (CF) of 5.4 was determined. Subsequent engine calibration and installation of a Selective Catalytic Reduction (SCR) device were conducted and tested on a fully transient engine dyno setup, which precisely reproduced the engine operation under the on-road RDE test. The NO reduction achieved with those upgrades was 90%, leading to a CF of 0.53, with no CO or fuel consumption penalty. These findings demonstrate that diesel vehicles can reach low NO levels under real world driving conditions, when well-designed modern exhaust aftertreatment components are installed and properly calibrated.
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ABSTRACT A new average CO2 emissions limit for passenger cars was introduced in EU in 2009 imposing gradual average CO2 emissions reduction to 130Â g/km until 2015. This paper attempts to study possible changes in vehicle characteristics... more
ABSTRACT A new average CO2 emissions limit for passenger cars was introduced in EU in 2009 imposing gradual average CO2 emissions reduction to 130Â g/km until 2015. This paper attempts to study possible changes in vehicle characteristics for meeting this limit taking into account the average European passenger car of 2007-2008. For this purpose first the most important factors affecting vehicle fuel consumption over the reference cycle (NEDC) are identified. At a second step, the CO2 benefit from the optimisation of these factors is quantified, through simulations of 6 different passenger cars commonly found in the European fleet. For the simulations Advisor 2002 was employed and validated against published type approval data. The analysis indicated that substantial reductions in vehicle weight, tyre rolling resistance and engine efficiency are necessary to reach even the 2008 target. A 10% reduction in average vehicle weight combined with 10% better aerodynamic characteristics, 20% reduced tyre rolling resistance and a 7.5% increase in average powertrain efficiency can lead to CO2 reductions of approximately 13% (about 138Â g/km based on 2007-2008 fleet-wide performance). Complying with the 130Â g/km within the next six-year timeframe will be a rather difficult task and additional technical measures appear to be necessary.
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Abstract A prototype mobile gasification-ICE unit for decentralized Combined Heat and Power (CHP) production is designed and constructed within the framework of the LIFE+ project “SMARt-CHP” for the energy utilization of agricultural... more
Abstract A prototype mobile gasification-ICE unit for decentralized Combined Heat and Power (CHP) production is designed and constructed within the framework of the LIFE+ project “SMARt-CHP” for the energy utilization of agricultural residues generated in Greek rural areas, where large amounts of biomass wastes are available. This unit applies the technology of biomass gasification coupled to an Internal Combustion Engine (ICE) for electricity generation. The CHP unit has a maximum output of 12 kWth in addition to approximately 5 kWel. The unit is tested and operated in different locations close to biomass feedstock origin in the rural areas of Western Macedonia in Greece. Peach, olive and grape kernels are utilized as biomass feedstock while the unit is operated constantly on a 24/7 basis overcoming technical issues. The present research work describes the unit performance in terms of constant operation, energy output and process efficiency by utilizing different agricultural residues. The obtained results show the effect of biomass type, gasification parameters and engine intake mixture to long-term operation and process efficiency. The unit envisages the production of cost effective renewable energy for rural areas while it promotes the concept of mobile energy production units that utilize by-products of agricultural and forestry activities, which are otherwise treated as waste.
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The introduction of selective catalytic reduction (SCR) aftertreatment to meet stringent diesel NOx emission standards around the world increases exhaust ammonia. Further to the direct air quality and health implications of ammonia, this... more
The introduction of selective catalytic reduction (SCR) aftertreatment to meet stringent diesel NOx emission standards around the world increases exhaust ammonia. Further to the direct air quality and health implications of ammonia, this may also lead to particle formation in the exhaust. In this study, an ammonia SCR system was examined with respect to its impact on both solid and total exhaust particle number and size distribution, downstream of a diesel particulate filter (DPF). Fuel post-injection was conducted in some tests to investigate the effect of ammonia during active DPF regeneration. On average, the post-DPF solid >23 nm and total <23 nm particle number emissions were increased by 129% (range 80-193%) and by 67% (range 26-136%), respectively, when 100 ppm ammonia level was induced downstream of the SCR catalyst. This is a typical level during ammonia overdosing, often practiced for efficient NOx control. Ammonia did not have a significant additional effect on the high particle concentrations measured during DPF regeneration. Based on species availability and formation conditions, sulfate, nitrate, and chloride salts with ammonium are possible sources of the new particles formed. Ammonia-induced particle formation corresponds to an environmental problem which is not adequately addressed by current regulations.
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This paper: contrasts the fuel efficiency and emissions characteristics of the automotive technologies of Iran and developed countries; studies the tail pipe emissions of various vehicle types; reviews the applicability of international... more
This paper: contrasts the fuel efficiency and emissions characteristics of the automotive technologies of Iran and developed countries; studies the tail pipe emissions of various vehicle types; reviews the applicability of international standards for tail pipe emissions to developing countries; and assesses various technological options for reducing greenhouse gas emissions for the tail pipes.
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The particulate emissions of a diesel passenger car running on 13 fuels (including a reference one), featuring major differences in aromatic content and minor differences in specific energy were measured, following the legislated European... more
The particulate emissions of a diesel passenger car running on 13 fuels (including a reference one), featuring major differences in aromatic content and minor differences in specific energy were measured, following the legislated European certification procedure. ...
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An investigation of the effects of metal-based fuel-borne catalysts on the loading and regeneration performance of Diesel Particulate Filters (DPFs) installed on a test vehicle is presented. A test protocol that comprises regeneration... more
An investigation of the effects of metal-based fuel-borne catalysts on the loading and regeneration performance of Diesel Particulate Filters (DPFs) installed on a test vehicle is presented. A test protocol that comprises regeneration attempts at steady state speeds following a loading phase for about 100 km was applied for the performance screening. None of the additives tested led to a complete regeneration of the filter under normal driving conditions. This was possible only if engine operation was modified in order to increase exhaust temperature. Methylcyclopentadienyl Manganese Tricarbonyl (MMT) in the higher concentration mixture in the fuel was found to be the most effective of the additives tested in terms of regeneration onset temperature.
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ABSTRACT A detailed study of the sulfation and desulfation phenomena of a NOx storage reduction catalyst using synthetic gas bench is presented. The experimental observations and results were put together, in order to develop a model,... more
ABSTRACT A detailed study of the sulfation and desulfation phenomena of a NOx storage reduction catalyst using synthetic gas bench is presented. The experimental observations and results were put together, in order to develop a model, which can simulate the NOx storage reduction catalyst behavior during the sulfation and desulfation conditions. The target is to use the model for simulation of the lean/rich desulfation strategies, in order to comprehend the complicated phenomena and ultimately predict the sulfur speciation at the outlet of the NOx storage reduction catalyst. Sulfation tests in the presence and in the absence of O2 at different temperatures were conducted, in order to identify the different sulfation sites. Desulfation tests with constantly rich conditions and lean/rich oscillation, using H2 as the reducing gas, were performed in order to investigate the reaction pathways of the decomposition of the sulfates. Additionally, some preliminary investigation was performed using CO and decane in the reducing gas mixture, in order to evaluate the NOx storage reduction behavior under more realistic gas composition for diesel exhaust gas. The important role of the accurate prediction of sulfur axial distribution at the desulfation onset was identified. It was found that cerium oxides play a critical role in the sulfation process by increasing the sulfur capacity of the NOx storage reduction catalyst. Finally, it was clarified that the oxygen stored on cerium oxides strongly affects the selectivity of the desulfation products by oxidizing H2S and controlling H2 availability.
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This paper presents the emission characteristics of a diesel passenger car operated on low sulphur fuels (8 and 38ppm) when fitted with either a catalysed diesel particle filter (DPF) or a non-catalysed one combined with a fuel-borne... more
This paper presents the emission characteristics of a diesel passenger car operated on low sulphur fuels (8 and 38ppm) when fitted with either a catalysed diesel particle filter (DPF) or a non-catalysed one combined with a fuel-borne catalyst. Measurements were conducted ...
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The importance of traffic on air quality has dropped in a financial crisis hit city. Biomass for domestic heating has significantly worsened the air in residential areas. Better control of biomass burning needed to alleviate air quality... more
The importance of traffic on air quality has dropped in a financial crisis hit city. Biomass for domestic heating has significantly worsened the air in residential areas. Better control of biomass burning needed to alleviate air quality impacts. a b s t r a c t Airborne urban particulate and gaseous pollutants measurements were conducted at the kerbside of a busy road and at a nearby urban background site of Thessaloniki, Greece, during a winter and a summer period. The main objective was to observe how the financial crisis has affected the air quality in the city, compared to previous measurements. Compared to a study conducted in 2006, the current work suggests that although average concentrations at the traffic affected site remain higher that in the urban background station, the differences are much smaller than in the past. A number of observations suggest a scenario of decrease in traffic activity and increase in biomass burning for residential heating. On this basis, the results suggest that traffic may be less important as an air quality contributor in a financially hit city. On the contrary, domestic heating appears as a significant contributor and affects areas of the city that were earlier not being of environmental concern. Because of the impact of biomass burning in residential areas, exposure calculations are required to estimate whether traffic or biomass burning is the overall highest contributors to daily PM dosages that citizens of the city are exposed to.