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2015 | Buch

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Nanoparticle Emissions From Combustion Engines

verfasst von: Jerzy Merkisz, Jacek Pielecha

Verlag: Springer International Publishing

Buchreihe : Springer Tracts on Transportation and Traffic

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

This book focuses on particulate matter emissions produced by vehicles with combustion engines. It describes the physicochemical properties of the particulate matter, the mechanisms of its formation and its environmental impacts (including those on human beings). It discusses methods for measuring particulate mass and number, including the state-of-the-art in Portable Emission Measurement System (PEMS) equipment for measuring the exhaust emissions of both light and heavy-duty vehicles and buses under actual operating conditions. The book presents the authors’ latest investigations into the relations between particulate emission (mass and number) and engine operating parameters, as well as their new findings obtained through road tests performed on various types of vehicles, including those using diesel particulate filter regeneration. The book, which addresses the needs of academics and professionals alike, also discusses relevant European regulations on particulate emissions and highlights selected methods aimed at the reduction of particulate emissions from automobiles.

Inhaltsverzeichnis

Frontmatter

Introduction

Abstract

Technological development in all fields of industry makes it necessary to reduce its negative impact on the environment. The use of advanced techniques and their developments make it necessary to continuously verify the working conditions of machinery and equipment and to analyse their impact on the environment and civilization. The automotive industry is recognized as a very dynamically developing branch; for this reason it is necessary to reduce, above all, emissions of harmful exhaust gas components. The emission of solid particles is a major threat to humans, and is a barrier to the development of modern internal combustion engines, especially engines with direct fuel injection (both diesel engines and gasoline engines). An important challenge for car manufacturers consists of subsequent projects on toxicity standards, according to which the emissions of particulate matter should be a few times lower than current levels.

Jerzy Merkisz, Jacek Pielecha

Characteristics of Particulate Matter Considering Particle Mass and Particle Number

Abstract

The form, size and composition of particulate matter depend to a large extent on location and temperature within the system: the cylinder - the exhaust system - the surroundings, where, depending on type of tests conducted, the particles are captured for measurements. For this reason, the most widely accepted way of defining particulate matter contains in its formula an element defining the conditions in which the emission measurements were carried out [19].

Jerzy Merkisz, Jacek Pielecha

The Process of Formation of Particulate Matter in Combustion Engines

Abstract

Solid particles are created as a result of complex chemical and physical processes, often occurring time, though the time and place of their occurrence are very different. The form, size and composition of PM depends to a large extent on the temperature and location within the system: the cylinder – the exhaust system – the surroundings, where the particles are collected [19, 20]. The final form of the emissions is affected by all intermediate stages, but in a particular cases different phases can be decisive [5]. However, typically the processes that occur in the engine cylinder shortly after fuel injection are most important. Their nature and characteristics are different for different engines, their operational conditions and fuels burned. Formation mechanisms of the individual components of emissions are also different.

Jerzy Merkisz, Jacek Pielecha

Methods of Measuring Particulate Matter Emissions

Abstract

According to the definition of particles, testing them requires dilution of the exhaust gas in the dilution tunnel at full or partial flow. Additional considerations to be taken into account when measuring are the degree of dilution, the mass of the filter before and after the measurement, the air humidity and the sample collection time. Tests of particle mass are therefore carried out in several stages; it is a long-term process, requiring that the filters be kept for 8 h in air at constant humidity and temperature, both before and after the measurement. This means that the results cannot be obtained directly during engine operation. Thus, the mass of particles collected on the measuring filter is an average value resulting from the collection time of the exhaust gas sample. This method is most commonly used to determine the mass of particulate matter at a certain time, e.g. for regular, repetitive operational conditions of the engine. The mass method for determining the mass of particulate matter does not guarantee obtaining data on the emission rate under variable conditions, e.g. while increasing the engine load; it is possible, however, to obtain the total mass of particles in these conditions over the selected time interval.

Jerzy Merkisz, Jacek Pielecha

Particulate Matter Emissions during Engine Start-Up

Abstract

Taking into account the continuous tightening of regulations limiting emissions of harmful compounds in the exhaust gas, it is essential to recognize the cause of such emissions and eliminate or reduce them [1, 2, 7, 8]. It is believed that one of these reasons is insufficient warm up of the engine, occurring primarily during cold start. Limits for emission of harmful compounds in the exhaust gas are forcing manufacturers to shorten the cold phase and at the same time to reduce the percentage share of emissions during cold start in the total emission of harmful substances emitted by the engine. Engine start-up and warm-up periods fall within the range of the tests currently in force, defining the amount of emissions of toxic compounds in exhaust gas. The amount of the emissions from these periods, due to the lack of the efficient operation of the exhaust gas purification systems (below 300°C), has a significant share in the final results of driving tests.

Jerzy Merkisz, Jacek Pielecha

Determination of Particulate Matter Equivalents

Abstract

Thanks to continuous improvements, equivalent methods and techniques for measuring particulate matter in the real traffic conditions have been created [2–10, 14–19]. Despite the very small emissions of these compounds, it is possible to measure them in variable traffic conditions [11, 13]. In this chapter, on the basis of a verification of the optical method (measuring exhaust gas opacity) conducted for different types of motor vehicles, it is shown that such measurements are subject to significant error and do not provide conclusive results. It should be noted that the measured value of the opacity of the exhaust gas may correspond to value of particle concentration (not emission) in the exhaust gas, but only for large particles which, by absorbing light, reduce the energy reaching the detector of the device. Ambiguity of the results is caused by their insufficient resolution and the lack of a proportional relationship between the mass of a particle and its size.

Jerzy Merkisz, Jacek Pielecha

Measurements of Particle Mass and Particle Number in Real Traffic Conditions

Abstract

The analysis of dynamic real traffic conditions of combustion engines can be reduced to the analysis of a given parameter with the following coordinates: vehicle speed – vehicle acceleration. Such a definition is similar to the analysis of the static characteristics of engines using coordinates of engine speed – engine load. If the whole vehicle with its drive unit is to be treated as a ‘closed object’ (a so-called black box), then the adoption of such an assumption allows for an analysis of the selected parameters of particulate matter, regardless of the internal changes taking place within the unit under consideration. This assumption does not preclude the simultaneous collection of data on the operation of the drive unit (such as engine speed and engine load from the OBD system [3, 4, 6, 11, 23, 36]).

Jerzy Merkisz, Jacek Pielecha

The Relationship between Particle Mass and Particle Number

Abstract

The possibility of establishing a correlation between the mass (or mass concentration) of particles and their number (or number concentration) seems to be interesting. This is a new research task, which due to the lack of clear regulations, has not been performed so far. Published results, e.g. in [5, 7, 8] differ substantially, different because of the different measuring methods and measurement conditions employed. This is associated mainly with the large range of particle diameters, as well as diversified particle number and the mass of a single particle (Table 8.1 and Fig. 8.1). The only constant parameter among the above parameters of particulate matter is particle density; this is accepted, as with establishing the aerodynamic diameter, as 1 g/cm³. This value is the adopted a priori, however it should be noted that it depends on the particle size and decreases with an increase in particle diameter (Fig. 8.2).

Jerzy Merkisz, Jacek Pielecha

Methods of Decreasing Emissions of Particulate Matter in Exhaust Gas

Abstract

In order to remove insoluble particulate matter from the exhaust gas, particulate filters are necessary. Particle filters operate by retaining particles, and then burning them in order to clean the filtering elements. Problems that occur during the construction and operation of filters are:

the size of the particles (mostly less than 1 μm),
soot ignition temperature without a catalytic converter (in the filter and/or fuel) is about 550-600°C, the burn-out temperature of can exceed 1000°C,
very high hydrocarbon emissions during burn-out (regeneration of the filter),
increased flow resistance due to the deposition of particulate matter on the filter during engine operation.

Jerzy Merkisz, Jacek Pielecha

Conclusions

Abstract

Limited resources of liquid fuels and prevention of the harmful emissions associated with the combustion of these fuels, as well as international competition are the main factors in the current rapid development of motor vehicles.

The main trends in the design of vehicles and their engines are currently determined by the requirements of provisions relating to the reduction of harmful emissions in the exhaust gas and carbon dioxide emissions [24, 27, 28].

Jerzy Merkisz, Jacek Pielecha

Titel: Nanoparticle Emissions From Combustion Engines
verfasst von: Jerzy Merkisz
Jacek Pielecha
Verlag: Springer International Publishing
Electronic ISBN: 978-3-319-15928-7
Print ISBN: 978-3-319-15927-0
DOI: https://doi.org/10.1007/978-3-319-15928-7