Maija Lappi

Emission Performance of Selected Biodiesel Fuels

Because of the great interest in biodiesel fuels around the world, the International Energy Agencys Committee on Advanced Motor Fuels sponsored this project to determine emissions and performance of a number of biodiesel fuels with a special emphasis on unregulated emissions. Oak Ridge National Laboratory (ORNL) and Technical Research Centre in Finland (VTT) carried out the project with complementary work plans. Several different engines were used between the two sites, and in some cases emissions control catalysts were used, both at ORNL and at VTT. ORNL concentrated on light and medium duty engines, while VTT emphasized a heavy-duty engine and also used a light duty car as a test bed. Common fuels between the two sites for these tests were rape methyl ester in 30% blend and neat, soy methyl ester in 30% blend and neat, used vegetable oil methyl ester (WOME) in 30% blend, and the Swedish environmental class 1 reformulated diesel (RFD). ORNL used ASTM 2D diesel as baseline, while VTT used EN 590 (European diesel) as the base. VTT also tested a blend of 30% UVOME with RFD. Steady state test cycles were used for all engines and fuels except for the light duty vehicle, which was tested on a chassis dynamometer using the US FTP 75 test. Results are presented for regulated emissions as well as for aldehydes and composition of particulate matter, and polyaromatic hydrocarbons. VTT also produced results of Ames tests on the mutagenicty of samples of particulate matter. Generally, the biodiesel fuels had higher NO x emissions but lower values of HC, CO, and particulates. Unregulated emissions varied greatly between fuels and engines.

A Novel Mobile Laboratory for “Chasing” City Traffic

A mobile laboratory was designed and built in Helsinki Polytechnic, in close co-operation with the University of Helsinki, to measure traffic pollutants with high temporal and spatial resolution under real world conditions. The laboratory provides measurements of gaseous pollutants and particle size number distributions as well as meteorological and geographical parameters. Two inlet systems are employed to enable the chasing of different type of vehicles. This paper introduces the construction and technical details of the mobile laboratory, and presents the results from chasing experiments performed in the Helsinki metropolitan area during a field campaign in June, 2003. New particle formation was found while driving in the exhaust plume of vehicles. Approximately 75% of the total particle number concentration was due to particles smaller than 50 nm in size. The shorter the distance from the chased vehicle, the higher nuclei mode number concentration was recorded owing to the reduced potential dilution time. Typical modal mean particle diameters were 7-15 nm and 70 nm.

Evaluation of thermal optical analysis method of elemental carbon for marine fuel exhaust

ABSTRACT The awareness of black carbon (BC) as the second largest anthropogenic contributor in global warming and an ice melting enhancer has increased. Due to prospected increase in shipping especially in the Arctic reliability of BC emissions and their invented amounts from ships is gaining more attention. The International Maritime Organization (IMO) is actively working toward estimation of quantities and effects of BC especially in the Arctic. IMO has launched work toward constituting a definition for BC and agreeing appropriate methods for its determination from shipping emission sources. In our study we evaluated the suitability of elemental carbon (EC) analysis by a thermal-optical transmittance (TOT) method to marine exhausts and possible measures to overcome the analysis interferences related to the chemically complex emissions. The measures included drying with CaSO4, evaporation at 40–180ºC, H2O treatment, and variation of the sampling method (in-stack and diluted) and its parameters (e.g., dilution ratio, Dr). A reevaluation of the nominal organic carbon (OC)/EC split point was made. Measurement of residual carbon after solvent extraction (TC-CSOF) was used as a reference, and later also filter smoke number (FSN) measurement, which is dealt with in a forthcoming paper by the authors. Exhaust sources used for collecting the particle sample were mainly four-stroke marine engines operated with variable loads and marine fuels ranging from light to heavy fuel oils (LFO and HFO) with a sulfur content range of <0.1–2.4% S. The results were found to be dependent on many factors, namely, sampling, preparation and analysis method, and fuel quality. It was found that the condensed H2SO4 + H2O on the particulate matter (PM) filter had an effect on the measured EC content, and also promoted the formation of pyrolytic carbon (PyC) from OC, affecting the accuracy of EC determination. Thus, uncertainty remained regarding the EC results from HFO fuels. Implications: The work supports one part of the decision making in black carbon (BC) determination methodology. If regulations regarding BC emissions from marine engines will be implemented in the future, a well-defined and at best unequivocal method of BC determination is required for coherent and comparable emission inventories and estimating BC effects. As the aerosol from marine emission sources may be very heterogeneous and low in BC, special attention to the effects of sampling conditions and sample pretreatments on the validity of the results was paid in developing the thermal-optical analysis methodology (TOT).

Estimating the distribution of particle dimensions from electron microscope images

An approach for estimating the distribution of soot particle dimensions from electron microscope images is studied. We have implemented simple image-analytical methods that produce an equivalent diameter distribution which can be compared with the corresponding distribution acquired via physical measurements. In comparison with manual object detection with conventional image processing software our method is time-saving and efficient. The shape of the particles emitted from the motor under different loads is affected by phenomena in exhaust dilution or release to air. Particle shape has a significant effect on its harmfulness to health. The researchers are also interested in knowing the actual particle size distribution to be able to improve catalyzer functionality. Engine exhaust particle emissions are often analyzed by methods based on the physical properties of soot particles, and assumptions about their size and shape. Our method provides data for refining these results. The implemented graphical user interface is semi-automatic and allows the user to remove erroneous results from the resulting thresholded image before the analysis. Then the task is to calculate the properties of interest over the particle population. We have written a toolbox with simple functions that realize the semi-automated analysis and the user interface for easy operation.

Comparison of filter smoke number and elemental carbon from thermal optical analysis of marine diesel engine exhaust

The interest on contribution of shipping to global warming and especially on polar ice melting has increased. The International Maritime Organization is working toward reporting and estimation of black carbon emissions from shipping. The filter smoke number method is discussed as one possible candidate for onboard determination of black carbon/soot concentration of the engine exhaust gas, and it has recently been considered as one of the best candidates for further evaluation in the International Council on Clean Transportation 4th workshop on marine black carbon emission. Proven, standardized technology and small size and simple operation of the filter smoke meter make it a potential choice for actual onboard use. In our study, we evaluated the validity of the filter smoke number method for measuring soot emission by looking at correlations between the filter smoke number and elemental carbon analyzed using thermal optical transmittance analysis. Until now the conversion of the filter smoke number to black carbon /soot emission has been performed with equations derived from high-speed engines operating with distillate fuels. We introduce optimized calculation parameters for filter smoke number to black carbon/soot conversion, which are derived from light and heavy fuel oil measurements. These new parameters can be utilized with improved accuracy for the estimation of the black carbon emission from filter smoke number measurement with marine fuel qualities.