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Despite the increasing popularity of hybrid-electric vehicles (HEVs), few studies have quantified their real-world particle emissions from internal combustion engine (ICE) re-ignition events (RIEVs). RIEVs have been known to occur under unstable combustion conditions which frequently result in particle number emission rates (PNERs) that exceed stabilized engine operation. Tailpipe total PN (5 to 560 nm diameter) emission rates (#/s) from a conventional vehicle (CV) and hybrid electric vehicle (HEV) 2010 Toyota Camry were quantified on a 50 km (32 mi) route over a variety of roadways in Chittenden County, Vermont using the Total On-board Tailpipe Emissions Measurement System (TOTEMS). While HEVs are known to have significant fuel conserving benefits compared to conventional vehicles, less is known about the relative emissions performance of HEVs. This study is the first to characterize RIEVs under a range of real-world driving conditions and to directly compare HEV and CV PNER during driving on different road sections. A total of 28 CV and 33 HEV sampling runs were conducted over an 18-month period under ambient temperatures ranging between -4 and 35 °C. A road classification based upon speed and intersection density divided the route into four different road sections: Freeway, Rural, Urban I and Urban II. Due to the distinct on-off cycling of the HEV ICE, a new operational mode framework (ICE OpMode) was developed to characterize shutdown, off, re-ignition and stabilized HEV ICE operation. Road section was found to affect overall ICE OpMode distribution, with HEV engine-off operation averaging 57%, 36% and 5% of total operation for combined Urban, Rural and Freeway road sections, respectively. Re-ignition frequency was found to range between 11 and 133 events per hour, with spatial density ranging between 0.1 and 5.6 events per kilometer of roadway. A total of 3212 re-ignition events were observed and recorded, and mean HEV PNER during RIEVs, on average, ranged between 2.4 and 4.4 times greater than that of HEV Stabilized operation. Approximately 65% of all re-ignition events resulted in a peak PNER exceeding the 95% percentile for all ICE-on activity in both vehicles (9.3 x 1011 #/s), known as a High Emission Event Record (HEER). RIEV operation made up only 7.4% of total ICE-on operation for both vehicles but accounted for 35.4% of all HEERs. Overall, total particles emitted during HEV operation associated with re-ignition events ranged from 5% for Freeway driving to 60% for Urban I driving. Comparisons between vehicles found an average of 37% and 7% fuel conserving benefits of the HEV during Urban I and Freeway driving, respectively. However, a different effect was found for PN emissions. During Urban I driving, where RIEVs were most frequent, on average HEV PNER was 2.3 times greater than overall mean CV PNER. For Freeway driving, where the HEV operated similar to a conventional vehicle, mean CV PNER was 2.4 times greater than mean HEV PNER. PNER from partial re-ignition events following an incomplete ICE shutdown (no period of prior engine off operation) were on average 1.65 times greater than those occurring when the ICE shutdown for at least one second. The typical fuel consumption benefits of HEVs in urban driving are associated with a tradeoff in PN emissions. The HEV ICE operating behavior has implications for the spatial distribution of PN hot-spots as well as the associated micro-scale modeling of alternative vehicle technology emissions. It is likely that building a model of HEV behavior based upon CV activity will be appropriate, with consideration of a hybridization factor and, as a result of these analyses, a re-ignition factor.

Es wurde ein flexibles Messsystem zur Messung von Anzahlgrößenverteilungen von Partikeln, den Spurengasen NOx und CO2 sowie einiger thermodynamischer Parameter im Abgasstrom eines Diesel-Pkw und eines Benzin-Pkw unter realistischen Fahrbedingungen entwickelt. Das Messsystem besteht aus einem SMPS (Scanning Mobility Particle Sizer) System, einem Multigas-Emissionsanalysator, Thermoelementen, Vaisala-Sensoren, einem Prandtl-Pitot-Rohr und einem Lyman-α-Hygrometer. Es wurde ein spezielles Einlasssystem entwickelt, das variabel im Abgasstrom platziert werden kann. Die Messfahrten wurden zwischen Oktober 2004 und April 2005, sowohl auf der Autobahn als auch im Stadtverkehr, durchgeführt. Die Probenahme erfolgte dabei in einem Abstand von bis zu 95 cm zum Auspuffrohr. Die Ergebnisse werden in der vorliegenden Arbeit dargestellt und diskutiert. Darüber hinaus werden Emissionsfaktoren für die Partikelanzahl individuell für beide Pkws bestimmt und mit Literaturdaten verglichen. Emissionsfaktoren werden zum Beispiel für die Festlegung von Grenzwerten benötigt.

The diploma thesis deals with the exposure of nanoparticles in means of transport. The diploma thesis provides an overview of the current state of exposure to nanoparticles in vehicles that people use every day travelling to work. Moreover, the work describes the health risks that can be caused by these particles and have an adverse effect on human health. The work processed data (particle number concentration, particle size and LDSA) which monitored the exposure of nanoparticles in the tram of public transport in the city of Brno and the extent of pollution by nanoparticles at stops.

Numerous studies have shown that respirable particles contribute to adverse human health outcomes including discomfort in irritated airways, increased asthma attacks, irregular heartbeat, non-fatal heart attacks, and even death. Particle emissions from diesel vehicles are a major source of airborne particles in urban areas. In response to energy security and global climate regulations, the use of biodiesel as an alternative fuel for petrodiesel has significantly increased in recent years. Particle emissions from diesel engines are highly dependent on fuel composition and, as such, the increased use of biodiesel in diesel vehicles may potentially change the concentration, size, and composition of particles in respirable air. One indicator used to evaluate the potential health risk of these particles to humans is particle diameter (Dp). Ultrafine particles (UFPs, Dp Current research in automotive emissions primarily focuses on particle emissions measured on a total particle mass (PM) basis from heavy-duty diesel vehicles. The nation's light-duty diesel fleet is, however, increasing; and because the mass of a UFP is much less than that of larger particles, the total PM metric is not sufficient for characterization of UFP emissions. As such, this research focuses on light-duty diesel engine transient UFP emissions, measured by particle number (PN), from petrodiesel, biodiesel, and blends thereof. The research objectives were to determine: 1) the difference in UFP emissions between petrodiesel and blends of waste vegetable oil-based biodiesel (WVO), 2) the differences between UFP emissions from blends of WVO and soybean oil-based biodiesel (SOY), and 3) the feasibility of using genetic programming (GP) to select the primary engine operating parameters needed to predict UFP emissions from different blends of biodiesel. The results of this research are significant in that: 1) Total UFP number emission rates (ERs) exhibited a non-monotonic increasing trend relative to biodiesel content of the fuel for both WVO and SOY that is contrary to the majority of prior studies and suggests that certain intermediate biodiesel bends may produce lower UFP emissions than lower and higher blends, 2) The data collected corroborate reports in the literature that fuel consumption of diesel engines equipped with pump-line-nozzle fuel injection systems can increase with biodiesel content of the fuel without operational changes, 3) WVO biodiesel blends reduced the overall mean diameter of the particle distribution relative to petrodiesel more so than SOY biodiesel blends, and 4) Feature selection using genetic programming (GP) suggests that the primary model inputs needed to predict total UFP emissions are exhaust manifold temperature, intake manifold air temperature, mass air flow, and the percentage of biodiesel in the fuel; These are different than inputs typically used for emissions modeling such as engine speed, throttle position, and torque suggesting that UFP emissions modeling could be improved by using other commonly measured engine operating parameters.

Today, emission legislations for engine exhaust particles are mass based. The engines of today are low-emitting with respect to particle mass, with the emissions approaching the detection limit of the current measurement method. This calls for new and improved measurement methods. Both from the point of view of the engine developers and regarding human health effects, particle number seem to be the particle property of greatest interest to legislate upon. Recently, a proposal for a new particle number based measurement methodology has been put forward by the United Nations Economic Commission for Europe (UN ECE). The gas and particle mixture (the aerosol) of engine exhaust is not a stable system. The size and the number of the particles change over time as the temperature and pressure change. Particle number measurements call for dilution which changes the gas-phase concentrations of the condensing gases. The dilution process alters the conditions in the aerosol and thereby influences the measurements. Within the current project it was desired to better understand the outcome of particle number measurements and the complexities of particle sampling, dilution and conditioning prior to measurements. Two experimental set-ups have been developed within the project. The first system includes a rotating disc diluter followed by a volatility Tandem Differential Mobility Analyser (v-TDMA). The second set-up, called the EMIR-system, includes ejector diluters in series followed by a stand-alone Condensation Particle Counter (CPC). After the development of these experimental set-ups, the v-TDMA has been used to study the volatility and the size distributed number concentration of exhaust particles. The EMIR-system was used for total number concentration measurements including only the solid fraction of the aerosol. The experimental work has given practical experience that can be used to estimate the benefits and disadvantages of upcoming measuring methodology. For the engine developers, in order to produce engines that meet future legislation limits, it is essential to know how the measurement procedure influences the aerosol. In summary, the experimental studies have shown that the number of nucleation mode particles is strongly affected by varied dilution. No upper threshold value of the dilution has been found where the dilution effect diminishes. The volatility studies have shown that it is mainly the nucleation mode particles that are affected by heat. The v-TDMA instrument have shown to be a sensitive analytical tool which, if desired to use for further engine exhaust particle characterization, needs some development work. Experimental work with the EMIR-system, which in principle is similar to the instruments proposed for a future standard, shows that these types of measurement systems are sensitive to small changes in the detector cut-off. The major outcome of the project lies in the new detailed knowledge about particle number measurements from engines. / QC 20100628

Die natürliche Umgebungsluft enthält Aerosolpartikel, deren Größe von wenigen Nanometern bis zu einigen Mikrometern reicht. Insbesondere anthropogenen ultrafeinen Partikeln, die kleiner als 100 nm sind, werden negative Wirkungen auf die menschliche Gesundheit zugeschrieben. Die gravimetrische Messung der Partikelmassekonzentration erfasst ultrafeine Partikel nur ungenügend, da die Masse dieser Partikel sehr gering ist. Deutlich empfindlicher gelingt die Quantifizierung ultrafeiner Partikel durch die Messung der Partikelanzahlkonzentration. Die Arbeit beschreibt ein Verfahren zur Messung der Anzahlkonzentration von Partikeln in Umweltaerosolen. Es verknüpft die elektrische Aufladung der Partikel mit deren Klassierung im elektrischen Feld und ihre Mengenbestimmung anhand der elektrischen Ladung. Mittels des entwickelten Sensormodells gelingt die Verbindung der gemessenen Rohdaten mit der Anzahlgrößenverteilung der Partikel durch eine Kernfunktion in einer Fredholmschen Integralgleichung erster Art. Zur Dateninversion wird diese Gleichung in diskreter Form als lineares Gleichungssystem genutzt. Dessen Koeffizienten bilden die Kernmatrix, welche mit einer neu entwickelten Methode experimentell bestimmt wird. Vergleichsmessungen zeigen eine gute Übereinstimmung des Verfahrens mit Referenzverfahren der Aerosolmesstechnik und unterstreichen die Eignung des Verfahrens zur Partikelquantifizierung in Umweltmessnetzen.

Particulate matter (PM) emitted from diesel engines encompasses soluble (volatile) and insoluble (non-volatile) matter. The concept of volatility or solubility depends on the method of separation. The volatile matter includes sulphates and nitrates which are bound to water vapour; and myriads of hydrocarbon species. The solid matter is comprised of black carbon and ash. Its mitigation combines the use of internal engine design and operating factors like fuel injection and spray, air and fuel mixing, chamber designs and fuel improvements. Control technologies that act on the exhaust gases are called ‘after-treatments' which include the use of oxidation catalysts, filter trap and reductant of nitrogen oxides along the exhaust system. The central issues of this thesis are measurement schemes that involve stripping the PM of volatile matter in order to determine the actual values of nano-size solid carbon particles that pose significant health risk and their mitigations. In the experimental measurements, exhaust gases were generated at low engine load which are rich in unburnt hydrocarbons that nucleate into particles at low temperatures. Similarly, exhaust gases generated at medium load contain volatile and soot components; these were used to study dilution effects on PM emission. The interplay of mixing and cooling was used to explain the behaviour of saturation characteristics of the volatile fractions in the dilution process which influenced nucleation of volatile species. The parameters of particle number concentration reduction factor (PCRF) and volatile removal efficiency (VRE) were used to give extended interpretation to dilution of PM during conditioning, than mere dilution ratios. On this basis, comparison was made on the effect of carrier gases on dilution process and it was found that air is superior when there is need for volatile reduction while nitrogen is better when it is necessary to freeze further reaction, especially at low dilution ratios. In addition, a two-stage hot dilution technique was used to mimic the Particle Measurement Programme (PMP) prescription, and it gave better PCRF and VRE values. The study of PM mitigation by filter traps focused on burning-off the accumulated matter to allow free flow of exhaust gases, and the energy it takes to initiate and maintain PM combustion. Therefore a fundamental study of soot oxidation relevant to regeneration of diesel particulate filter (DPF) was made. This was extended to investigate if blending of petrodiesel with biodiesel affects PM oxidation. It is deducible that oxidation of PM generated from fuel with biodiesel blends is slightly faster compared to that from pure petrodiesel. A feasible use of microwave power to regenerate catalysed and non-catalysed silicon carbide (SiC) diesel particulate filters (DPFs) using an available multimode microwave cavity was also carried out. Results show that with catalysed DPFs, catalyst light-off temperature reduced by 100oC under the influence of microwave irradiation, while for non-catalysed DPF, regeneration was achieved within 550-600oC at a time estimated to be lower compared to electrical resistance heating approach.

In der oberen Troposphäre und untersten Stratosphäre (OT/US) beeinflussen Aerosolpartikel im Submikrometerbereich den Strahlungshaushalt der Erde direkt und, was noch wichtiger ist, indirekt, da sie als Kondensationskern für Wolken dienen und somit die Spurengaskonzentrationen durch heterogene chemische Prozesse ändern können. Seit 1997 gibt es regelmäßige in situ Messungen der OT/US Partikel durch das Leibniz-Institut für Troposphärenforschung in Leipzig, Deutschland. Diese Messungen werden an Bord eines Passagierflugzeugs mit dem weltweit einzigartigen IAGOS-CARIBIC Messcontainer durchgeführt (www.iagos.org/iagos-caribic). In der vorliegenden Arbeit wurden die Partikelanzahlkonzentration und die Partikelgrößenverteilung im Submikrometerbereich der vergangenen Jahre ausgewertet. Dafür wurden die Daten von drei Kondensationspartikelzählern (CPC, Condensation Particle Counter) und einem optischen Partikelgrößenspektrometer (OPSS, Optical Particle Size Spectrometer) verwendet. Zunächst wurde im Labor eine umfangreiche Charakterisierung des IAGOS-CARIBIC OPSS hinsichtlich der Zähleffizienz durchgeführt. Weiterhin wurde eine Kalibrierung mit Polystyrol-Latex im geräterelevanten Bereich von 140 nm bis 1050 nm vorgenommen und daraus mit Hilfe der Mie-Streuung eine Funktion zur Datenauswertung für die OT/US entwickelt. Die statistische Analyse der IAGOS-CARIBIC OPSS und CPC Daten gibt einen guten Überblick über die in der OT/US vorkommenden Partikelanzahlkonzentrationen und stellt sicher, dass ein statistisch fundierter Datensatz für die Analyse zur Verfügung steht. Auf dieser Grundlage wurde zum ersten Mal eine detaillierte Analyse der raumzeitlichen Verteilung der Aitkenmode- und Akkumulationsmode-Partikelanzahlgrößenverteilung in der OT/US vorgenommen. Diese Analyse beinhaltet Weltkarten mit Medianwerten, Wahrscheinlichkeitsdichtefunktionen für spezielle Flugrouten und Partikelgrößenverteilungen entlang der Längengrade. Außerdem wurden die Partikelanzahlkonzentrationen zum ersten Mal mit dem globalen Klimamodell ECHAM-HAM verglichen. Dabei ergab sich, dass die Partikelanzahlkonzentration hauptsächlich von großräumigen Strömungsverhältnissen beeinflusst wird, was im Großen und Ganzen gut vom Modell wiedergegeben wird. Für die einzelnen Jahreszeiten wurden mit Hilfe der potentiellen Temperatur und äquivalenten Breitengrade die vertikalen Profile ausgewertet. Für die Analyse in Bezug auf die Aerosol-Mikrophysik und den Transport durch die Tropopause wurden auch die in IAGOS-CARIBIC gemessenen Spurengase, wie z.B. Ozon und Wasserdampf, hinzugezogen. Die Auswertung zeigt ebenfalls deutlich den Einfluss von Wolken in der oberen Troposphäre und verschiedene Austauschprozesse zwischen der Stratosphäre und Troposphäre. Außerdem wurde der Einfluss verschiedener Austauschprozesse auf die Partikelanzahlkonzentration untersucht: die Brewer-Dobson Zirkulation, warm conveyor belts, Isentropentransport und der Transport durch tropische, hochreichende konvektive Bewölkung. In der Vergangenheit wurde diese Analyse nur für atmosphärische Spurengase durchgeführt, und nun zum ersten Mal auch für Aerosolpartikel. Die hier präsentierten Ergebnisse zeigen eine umfangreiche Charakterisierung der Aitken- und Akkumulationsmode-Partikelanzahlkonzentration in der OT/US und den Einfluss von Austauschprozessen der Stratosphäre und Troposphäre auf die Partikel. Die Auswertungen tragen maßgeblich zum Verständnis und zur Vorhersage der Partikelanzahlkonzentration in Klimamodellen und damit schlussendlich zur Berechnung des Strahlungshaushalts der Erde und dessen zeitlicher Veränderung bei. / Submicrometer aerosol particles in the upper troposphere and lowermost stratosphere (UT/LMS) influence the Earth's radiation budget directly and, more important, indirectly, by acting as cloud condensation nuclei and by changing trace gas concentrations through heterogeneous chemical processes. Since 1997, regular in situ measurements of UT/LMS particles have been conducted by the Leibniz Institute for Tropospheric Research, Leipzig, Germany, using the world-wide unique IAGOS-CARIBIC observatory (www.iagos.org/iagos-caribic) onboard a passenger aircraft. In this thesis, UT/LMS aerosol particle number concentrations and the submicrometer aerosol particle size distribution as measured by three condensation particle counters (CPCs) and one Optical Particle Size Spectrometer (OPSS) are discussed. Before analyzing the measurement data from the UT/LMS region a throughout characterization of the IAGOS-CARIBIC OPSS with respect to the counting efficiency was carried out in the laboratory for the OPSS-relevant particle size range of 140 nm to 1040 nm diameter. After calibration with polystyrene latex (PSL) particles a theoretical response function, representative for the UT/LMS, was calculated with Mie theory to ensure a correct data analysis. The statistical analysis of the IAGOS-CARIBIC OPSS and CPC data gives a good overview of existing particle number concentrations in the UT/LMS and ensures a statistically sound data analysis. On this basis a detailed characterization of the spatio-temporal distribution of Aitken and accumulation mode particle number concentrations in the UT/LMS was carried out for the first time. This analysis includes global maps with median values, probability density functions for specific flight routes, and longitudinal distributions of the particle size distribution. Also a first comparison with the global climate model ECHAM-HAM was conducted. The analysis showed that the aerosol distributions are mainly influenced by large-scale circulation patterns which were, in gererel terms, well reflected by the global climate model. Moreover, seasonal vertical cross-sections for particle number concentrations, the potential temperature, and the equivalent latitude were generated. The results are interpreted with respect to aerosol microphysics and cross-tropopause transport using IAGOS-CARIBIC trace gases like ozone and water vapor. The influence of clouds in the troposphere and the different stratosphere-troposphere exchange processes are clearly visible. Furthermore, the influence of the major transport processes into the UT/LMS region on the aerosol particle number concentrations was investigated: the Brewer-Dobson circulation, warm conveyor belts, isentropic transport, and tropical deep convective cloud outflow. In the past this was done only for atmospheric trace gases, but now for the first time for aerosol particles. The findings presented in this study represent a comprehensive characterization of the Aitken and accumulation mode particle number concentration in the UT/LMS and the influence of stratospheric-tropospheric exchange processes on these particles. These findings may help to evaluate and improve predictions of particle number concentrations by climate models and finally the calculation of the Earth's radiation budget and its change over the years.

Es wurde ein flexibles Messsystem zur Messung von Anzahlgrößenverteilungen von Partikeln, den Spurengasen NOx und CO2 sowie einiger thermodynamischer Parameter im Abgasstrom eines Diesel-Pkw und eines Benzin-Pkw unter realistischen Fahrbedingungen entwickelt. Das Messsystem besteht aus einem SMPS (Scanning Mobility Particle Sizer) System, einem Multigas-Emissionsanalysator, Thermoelementen, Vaisala-Sensoren, einem Prandtl-Pitot-Rohr und einem Lyman-α-Hygrometer. Es wurde ein spezielles Einlasssystem entwickelt, das variabel im Abgasstrom platziert werden kann. Die Messfahrten wurden zwischen Oktober 2004 und April 2005, sowohl auf der Autobahn als auch im Stadtverkehr, durchgeführt. Die Probenahme erfolgte dabei in einem Abstand von bis zu 95 cm zum Auspuffrohr. Die Ergebnisse werden in der vorliegenden Arbeit dargestellt und diskutiert. Darüber hinaus werden Emissionsfaktoren für die Partikelanzahl individuell für beide Pkws bestimmt und mit Literaturdaten verglichen. Emissionsfaktoren werden zum Beispiel für die Festlegung von Grenzwerten benötigt.