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Volatility and number measurement of diesel engine exhaust particles
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

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.

Place, publisher, year, edition, pages
Stockholm: Maskinkonstruktion , 2007. , 95, 28 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2007:06
Keyword [en]
particle emissions, measuring methods, particle number measurements, dilution, rotating disc diluter, v-TDMA
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-4482ISBN: 978-91-7178-753-8 (print)OAI: oai:DiVA.org:kth-4482DiVA: diva2:12482
Public defence
2007-09-28, F3, Lindstedtsv. 26, Stockholm, 14:00
Opponent
Supervisors
Note
QC 20100628Available from: 2007-09-07 Created: 2007-09-07 Last updated: 2010-06-29Bibliographically approved
List of papers
1. Experimental Evaluation of a Rotating Disc Diluter
Open this publication in new window or tab >>Experimental Evaluation of a Rotating Disc Diluter
(English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851Article in journal (Refereed) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-7448 (URN)
Note
QC 20100628Available from: 2007-09-07 Created: 2007-09-07 Last updated: 2017-12-14Bibliographically approved
2. Study of Particulate Emissions from Heavy-Duty Diesel Engines using a Rotating Disc Diluter and a Volatility Tandem DMA (v-TDMA)
Open this publication in new window or tab >>Study of Particulate Emissions from Heavy-Duty Diesel Engines using a Rotating Disc Diluter and a Volatility Tandem DMA (v-TDMA)
2004 (English)Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-7449 (URN)
Conference
FISITA 2004 World Automotive Congress, May 23-27, Barcelona, Spain
Note
QC 20100628Available from: 2007-09-07 Created: 2007-09-07 Last updated: 2010-07-15Bibliographically approved
3. Characterization of Tailpipe Exhaust Particles using a Rotating Disc Diluter and a Volatility Tandem DMA (v-TDMA)
Open this publication in new window or tab >>Characterization of Tailpipe Exhaust Particles using a Rotating Disc Diluter and a Volatility Tandem DMA (v-TDMA)
2006 (English)In: SAE 2006 Transactions Journal of Fuels and Lubricants, 2006, Vol. 2006-01-3367Conference paper, Published paper (Refereed)
Abstract [en]

A v-TDMA instrument has been used to study the tailpipe exhaust particles of a heavy-duty Diesel engine equipped with a continuously regenerating trap (CRT) running at two different steady state conditions: high speed / medium load and medium speed / high load. The sample was extracted directly out of the engine and conditioned by use of a rotating disc diluter. This paper deals with measurements where the parallel mode of the v-TDMA instrument was used. A temperature of 350 °C was applied in the heated section of the v-TDMA to study the thermal stability of the particles. Dilution between 86 and 1740 times were applied to see if the amount of dilution affected the particle behavior. The CRT reduces the number concentration of accumulation mode particles by 90%. When using the CRT, high numbers of nucleation mode particles are measured that can be volatilized at 350° in the v-TDMA instrument. For nucleation mode particles, changing the dilution from 86 to 386 times can suppress particle formation by up to 90%. The present work shows that the rotating disc diluter together with the v-TDMA instrument are promising tools for study of exhaust particles sampled directly out of the engine.

Series
SAE Technical Papers
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-7450 (URN)10.4271/2006-01-3367 (DOI)2-s2.0-84877427068 (Scopus ID)
Conference
SAE Powertrain & Fluid Systems Conference 2006, Toronto, Canada
Note

QC 20100628

Available from: 2007-09-07 Created: 2007-09-07 Last updated: 2014-11-06Bibliographically approved
4. Number measurements of diesel exhaust particles - Influence of dilution and fuel sulphur content
Open this publication in new window or tab >>Number measurements of diesel exhaust particles - Influence of dilution and fuel sulphur content
2007 (English)In: SAE Technical Paper 2007-01-0064, 2007, Vol. 2007-01-0064, 2007-01-0064- p.Conference paper, Published paper (Refereed)
Abstract [en]

A volatility tandem differential mobility analyzer (v-TDMA) in parallel mode with the heated section at 350 °C has been used to study the number size distribution of exhaust particles from a heavy-duty Diesel engine equipped with a continuously regenerating trap (CRT). Total number concentrations have also been measured by use of a stand-alone CPC preceded by a heater at 350 °C. The sample was extracted directly from the exhaust pipe and conditioned by use of a rotating disc diluter. Two different dilution factors were applied (86 and 386 times) showing that the higher dilution reduces the number of small particles as particle formation is partly suppressed. Two different Diesel fuel qualities have been used showing that the 400 ppm sulphur fuel generates higher numbers of nucleation mode particles than the 3.5 ppm sulphur fuel. Particles formed with the 400 ppm sulphur fuel are present also after heating the aerosol to 350 °C which is not the case for equally sized particles formed when using the 3.5 ppm sulphur fuel. The different shapes of the particle size distributions for each of the fuels indicate that a minor change in cut-off size of the particle counter for number concentration measurements will correspond to a large difference in number of particles. The current study points out some of the difficulties encountered when trying to state an integrated value for particle emissions.

Keyword
Diesel fuels, Size distribution, Sulfur
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-7451 (URN)10.4271/2007-01-0064 (DOI)2-s2.0-84877434499 (Scopus ID)
Conference
Fuels and Emissions Conference; Cape Town; South Africa; 23 January 2007 through 25 January 2007
Note

QC 20100628

Available from: 2007-09-07 Created: 2007-09-07 Last updated: 2014-10-28Bibliographically approved
5. Number Measurements and Size Dependent Volatility Study of Diesel Exhaust Particles
Open this publication in new window or tab >>Number Measurements and Size Dependent Volatility Study of Diesel Exhaust Particles
2007 (English)In: SAE Technical Paper 2007-24-0107, 2007, Vol. 2007-24-0107, 10.4271/2007-24-0107- p.Conference paper, Published paper (Refereed)
Abstract [en]

An in-house developed volatility tandem differential mobility analyzer (v-TDMA) instrument in tandem mode has been used to study the exhaust particles of a heavy-duty Diesel engine equipped with a continuously regenerating trap (CRT) at two steady state conditions: medium speed / 100 % load and high speed idle. By use of the tandem mode of the v-TDMA instrument, particles in a narrow size range are led to the heater and the size dependent volatility can be studied. A rotating disc diluter was used to condition the sample. Temperatures between ambient temperature and 350 °C have been applied to study the volatility of the particles. The current work indicates that particles generated at high load have the same size after heating as before being heated. At high speed idle, small fractions of material can be found as smaller sized particles after heating. The study is an attempt to obtain size dependent information about engine exhaust particles. The main contribution is in the size distributed information about particle volatility. The current work also shed some light on the complexities of size separated particle number measurements.

Keyword
Automobile engines, Exhaust systems (engine)
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-7452 (URN)10.4271/2007-24-0107 (DOI)2-s2.0-84882679306 (Scopus ID)
Conference
8th International Conference on Engines for Automobile, ICE 2007; Capri, Naples; Italy; 16 September 2007 through 20 September 2007
Note

QC 20100628

Available from: 2007-09-07 Created: 2007-09-07 Last updated: 2014-10-28Bibliographically approved

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