Leonidas Ntziachristos

Leonidas Ntziachristos
Aristotle University of Thessaloniki | AUTH · School of Mechanical Engineering

Professor

About

190
Publications
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7,624
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Publications

Publications (190)
Article
Full-text available
This review provides a community's perspective on air quality research focusing mainly on developments over the past decade. The article provides perspectives on current and future challenges as well as research needs for selected key topics. While this paper is not an exhaustive review of all research areas in the field of air quality, we have sel...
Article
This study presents the energy consumption of Battery Electric Vehicles (BEVs) and Internal Combustion Engine (ICEVs: Petrol, Diesel) over more than 100 driving cycles. This aims at identifying the relative impact of a range of traffic conditions on the energy consumption of powertrains. Minimum consumption of BEVs appears at low-speed urban traffi...
Article
Concerns regarding noxious emissions from internal combustion engines have increased over the years. There is a strong need to understand the nature of sub-23 nm particles and to develop measurement techniques to evaluate the feasibility of new regulations for particle number emissions in the sub-23 nm region (down to at least 10 nm). This paper pr...
Article
Full-text available
Road transport significantly contributes to air pollution in cities. Emission regulations have led to significantly reduced emissions in modern vehicles. Particle emissions are controlled by a particulate matter (PM) mass and a solid particle number (SPN) limit. There are concerns that the SPN limit does not effectively control all relevant particu...
Article
The current study investigates gaseous and particulate emissions of a diesel passenger car (Euro 6d-temp), under specific operation events, including diesel particulate filter (DPF) active regeneration. The contribution of DPF active regeneration to sub-23nm volatile and solid particle emissions was investigated in a dedicated measurement campaign....
Chapter
Full-text available
The operation of a diesel power station located near the urban area of Mytilene has resulted in elevated air pollution levels throughout the past decades, especially during the summer period. In order to assess the polluting potential of the plant, an evaluation of emissions from the diesel generators was performed on the basis of average and trans...
Article
The maritime sector is characterized by high contribution in the emission of harmful pollutants such as NOX, PM, and SOX. The sector is making decisive steps to drastically reduce its environmental footprint by applying new technology and fuels as a reaction to the increasingly stringent emissions regulatory framework. In order to calculate the con...
Article
Full-text available
The maritime sector significantly contributes on the major environmental problems that humanity is being confronted with their consequences. The Greenhouse Gases (GHGs) emitted from the sector, which are responsible for the global phenomenon of climate change, are estimated in 2,89% of total anthropogenic GHGs. Ships are also an important source of...
Preprint
Full-text available
This review provides a community's perspective on air quality research focussing mainly on developments over the past decade. The article provides perspectives on current and future challenges as well as research needs for selected key topics. While this paper is not an exhaustive review of all research areas in the field of air quality, we have se...
Article
Full-text available
Attention to Black Carbon (BC) has been rising due to its effects on human health as well its contribution to climate change. Measurements of BC are challenging, as currently used devices are either expensive or impractical for continuous monitoring. Here, we propose an optoacoustic sensor to address this problem. The sensor utilizes a novel ellips...
Article
Full-text available
A vehicle’s air drag coefficient (Cd) and rolling resistance coefficient (RRC) have a significant impact on its fuel consumption. Consequently, these properties are required as input for the certification of the vehicle’s fuel consumption and Carbon Dioxide emissions, regardless of whether the certification is done via simulation or chassis dyno te...
Article
Shipping is the main source of anthropogenic particle emissions in large areas of the globe, influencing climate, air quality, and human health in open seas and coast lines. Here, we determined, by laboratory and on-board measurements of ship engine exhaust, fuel-specific particle number (PN) emissions for different fuels and desulfurization applie...
Technical Report
Full-text available
In March 2020 MSC-W hosted an expert workshop on condensable organic compounds (funded by the Nordic Council of Ministers, NMR), which brought together experts in emissions, measurements, emission inventories, atmospheric chemistry, air quality models and policy from Europe and North America, to create a much better understanding of the issues and...
Article
The current study investigates the nonvolatile particle number emissions of three bi-fuel passenger cars (Euro 6b, 6d-temp), which operate on compressed natural gas (CNG), as a primary fuel, and gasoline as a secondary one. The CNG fuel was injected into the engine using port fuel injection (PFI) while the gasoline fuel was either by PFI or by dire...
Article
The latest generation of internal combustion engines may emit significant levels of sub-23 nm particles. The main objective of the Horizon 2020 “DownToTen” project was to develop a robust methodology and provide policy recommendations towards the particle number (PN) emissions measurements in the sub-23 nm region. In order to achieve this target, a...
Article
This study offers emission factors for earlier and late technology medium duty diesel particulate filter (DPF) -equipped trucks, operating on real-world conditions. The analysis includes levels of nitrous oxide (N2O) emissions as well as the impacts of DPF regenerations on emission levels. The real-driving gaseous and particulate emissions, as well...
Article
Full-text available
The current experimental study presents particulate emissions from 30 Euro 1-4 L-category vehicles (i.e. 2-, 3- and 4-wheelers such as mopeds, motorcycles, quads and minicars, registered in Europe between 2009 and 2016) tested on a chassis dynamometer. The objectives were to identify those sub-categories with high emissions, to assess whether the m...
Article
The current experimental study presents solid (non-volatile) particle number emissions with a size cut-off at 23 nm (SPN23, referred to as PN hereinafter) under real-world driving conditions for 8 passenger cars powered by diesel, gasoline, Liquefied Petroleum Gas (LPG), Compressed Natural Gas (CNG) and hybrid-electric powertrains. The objective wa...
Article
This study aims to demonstrate a new approach for estimating fuel consumption from vehicles circulating on urban roads with different levels of congestion. A microscopic dynamic traffic model (AIMSUN) was coupled with an instantaneous emissions model (CRUISE) and their output was used to refine the average speed model (COPERT) functions. The integr...
Article
Full-text available
Heavy-duty diesel trucks (HDDTs) comprise a key source of road transport emissions and energy consumption worldwide mainly due to the growth of road freight traffic during the last two decades. Addressing their air pollutant and greenhouse gas emissions is therefore required, while accurate emission factors are needed to logistically optimize their...
Article
Full-text available
Emissions from passenger cars are one of major sources that deteriorate urban air quality. This study presents characterization of real-drive emissions from three Euro 6 emission level passenger cars (two gasoline and one diesel) in terms of fresh particles and secondary aerosol formation. The gasoline vehicles were also characterized by chassis dy...
Conference Paper
Full-text available
Shipping is facing major challenges with decarbonising targets (2050) and tightening emission regulations. SOx is already limited in the Emission Control Areas (ECA), and global limit for fuel sulphur content of 0.5 wt-% will apply in 2020. Tight Tier III NOx limits are applied for new builds in the NOx ECAs. So far, there is not explicit particula...
Article
Full-text available
Particle emissions and secondary aerosol formation from precursors from internal combustion engines deteriorate air quality and significantly affect human wellbeing and health. Both the direct particle emissions and the atmospheric emissions of compounds contributing the secondary aerosol formation are highly dependent on choices made in selecting...
Article
The current study investigates the effect of diesel fuel density, cetane number (CN), polycyclic aromatic hydrocarbons (PAH) and fatty acid methyl ester (FAME) content on the mass, size distribution, and chemical composition of particulate matter emissions from modern light-duty vehicles. Thirteen test fuels were evaluated against a reference one o...
Article
Full-text available
The scientific literature indicates that solid particle number (SPN) emissions of motorcycles are usually higher than that of passenger cars. The L-category (e.g., mopeds, motorcycles) Euro 4 and 5 environmental steps were designed to reduce the emissions of particulate matter and ozone precursors such as nitrogen oxides and hydrocarbons. In this s...
Article
Full-text available
The particulate matter (PM) emissions of gasoline vehicles were much lower than those of diesel vehicles until the introduction of diesel particulate filters (DPFs) in the early 2000s. At the same time, gasoline direct injection (GDI) engines started to become popular in the market due to their improved efficiency over port fuel injection (PFI) one...
Conference Paper
Current study aims to investigate sub-23nm solid particles (SPN<23nm) from spark ignition engine using compressed natural gas (CNG) as a primary fuel working in port fuel injection (PFI) mode and gasoline working as direct injection (GDI). For that reason, a state-of-the-art exhaust gas sampling system used for solid particle detection up to 2.5nm....
Technical Report
Full-text available
The emissions from transport and residential sectors have significant shares in total emissions of Europe. In this study, we identified key priorities in support to the EU Macro-regional Strategies implementation based on an ex-ante assessment focusing on two EU macro-regions: Adriatic-Ionian (AIR) and Alpine (ALP).
Article
Full-text available
In order to meet stringent fuel sulfur limits, ships are increasingly utilizing new fuels or, alternatively, scrubbers to reduce sulfur emissions from the combustion of sulfur-rich heavy fuel oil. The effects of these methods on particle emissions are important, since particle emissions from shipping traffic are known to have both climatic and heal...
Article
The current study presents a detailed analysis of the gaseous emissions, focusing on CO 2 and NO x , of diesel vehicles under several operating conditions. An assessment is also made on the impact and effectiveness of the Real Driving Emissions (RDE) test, which is mandatory by the European Union (EU) type approval regulation for passenger cars sin...
Article
Full-text available
Problems related to the quality of life in big cities are increasingly relevant, especially with regard to environmental issues. Motor transport is responsible for pollutant emissions and noise that decisively affect life in modern cities. In this context, evaluating, monitoring and forecasting urban environmental quality in short-term and long-ter...
Article
Full-text available
Real-driving emissions of NOx, CO, and THC, as well as fuel consumption (FC) were studied from 18 liquefied petroleum gas (LPG) fueled taxis operating in a metropolitan road network. Euro 2 to Euro 5 technology vehicles were measured with the use of portable emission measurement systems (PEMS). Statistical processing was implemented to derive mean...
Article
Full-text available
This study investigates pollutant emissions and fuel consumption of six Euro VI hybrid-diesel public transport buses operating on different scheduled routes in a metropolitan urban road network. Portable emission measurement systems (PEMS) are used in measurements and results are compared to those obtained from a paired number of Euro V conventiona...
Conference Paper
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,...
Article
Full-text available
The performance of a thermal denuder (thermodenuder—TD) and a fresh catalytic stripper (CS) was assessed by sampling laboratory aerosol, produced by different combinations of sulfuric acid, octacosane, and soot particles, and marine exhaust aerosol produced by a medium-speed marine engine using high sulfur fuels. The intention was to study the effi...
Article
Increasing divergence in fuel consumption and associated carbon dioxide (CO2) emissions between certification and in-use levels has called for improvements in passenger car type-approval procedure. The procedure used for vehicle certification in the European Union changes in September 2017. The first objective was to explore whether the new procedu...
Conference Paper
Full-text available
The gap between real-world and type approval CO 2 emission values is growing, and the forthcoming WLTP is expected to have limited impact to close that gap. Laboratory tests take place in idealized circumstances, which do not capture all of the usual conditions experienced during daily driving and such a test can be optimized for attaining low CO2...
Article
Τhis study demonstrates the combination of a microscopic traffic simulator (AIMSUN) with an instantaneous emissions model (AVL CRUISE) to investigate the impact of traffic congestion on fuel consumption on an urban arterial road. The micro traffic model was enhanced by an improved car-following law according to Morello et al. (2014) and was calibra...
Conference Paper
Full-text available
Global warming and the associated climate change are among the greatest problems of today, primarily caused by the greenhouse gases (GHG) produced by fossil fuels combustion. In Europe, the transport sector is responsible for 23% of total manmade GHG emissions, from which 44% is produced solely by passenger cars. In order to meet future commitments...
Article
The objective of this study was to test the potential for NOx 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...
Article
This work presents a new set of exhaust particulate emission factors for light and heavy duty vehicles and different driving conditions (urban, rural and highway). The emission factors, building upon COPERT methodology, are expressed in terms of particulate mass (PM), particle number (PN) and as particle size distributions, addressing current and f...
Article
In this article we present a design of a new miniaturized sensor with the capacity to measure exhaust particle concentrations on board vehicles and engines. The sensor is characterized by ultra-fast response time, high sensitivity, and a wide dynamic range. In addition, the physical dimensions of the sensor enable its placement along the exhaust li...
Article
This study contributes to the understanding of cycle-to-cycle emissions variability (CEV) in premixed spark-ignition combustion engines. A number of experimental investigations of cycle-to-cycle combustion variability (CCV) exist in published literature; however only a handful of studies deal with CEV. This study experimentally investigates the imp...
Article
Full-text available
The paper presents an overview of the final results of the 7FP ICT-EMISSIONS project that developed and validated a novel methodology and tool set to evaluate the impact of ICT-related transport measures on mobility and CO2 emissions of vehicle fleets under real-world conditions. The methodology combines traffic and emission modelling at micro and...
Article
Particle emission characteristics for a medium-speed four-stroke marine diesel engine were studied using a variety of sampling systems. Measurements were conducted at 25% and 75% load employing a heavy fuel oil (HFO) and a lighter marine distillate oil. The measurements, especially with HFO, revealed that marine exhaust particles mostly consist of...
Article
This study reports high numbers of exhaust emissions particles during engine motoring. Such particles were observed in the exhaust of two heavy duty vehicles with no diesel particle filter (DPF), driven on speed ramp tests and transient cycles. A significant fraction of these particles was non-volatile in nature. The number-weighted size distributi...
Article
In this study we explore the performance of a recently introduced exhaust particle detection concept, the dual PPS (dPPS), to simultaneously measure motor vehicle exhaust particle size, number, and mass in real-time. To this end, the dPPS was evaluated in two laboratories in measuring diesel and gasoline direct injection (GDI) exhaust particulate m...
Article
Diesel NOx emissions have been at the forefront of research and regulation scrutiny as a result of failures of late vehicle technologies to deliver on-road emissions reductions. The current study aims at identifying the actual emissions levels of late light duty vehicle technologies, including Euro 5 and Euro 6 ones. Mean NOx emission factor levels...
Chapter
In this chapter, the authors present a study on the impact of a variety of super credit scenarios on type-approval and real-world CO2 emissions with respect to the new fleet and the total passenger car fleet. The study assumes different electric vehicle penetration scenarios upon which the super credit scenarios are based. The case study investigat...
Chapter
Full-text available
This chapter discusses the main points of COPERT Micro methodology, focusing on input data, vehicle classification, emission factors and the calculation procedure. It presents the software and its user interface and demonstrates two typical case studies that were handled with COPERT Micro. COPERT Micro can be used in a number of applications. Its m...
Chapter
This chapter deals with the quantification of road transport non-exhaust particulate matter (PM) emissions in terms of emission factors (EFs). It presents the methodology applied for the determination of the EFs of various key pollutants and the vehicle categories taken into account and discusses the database produced. The pollutants include PM2.5,...