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Cold operability is estimated by fuel's cold filter plugging point (CFPP). However, correlation of CFPP with diesel vehicle performance originates from a period when simple in-line or distributor fuel injection systems were applied and fuels did not contain biocomponents. Today, common rail fuel injection systems are used and there seem to be remarkable differences in their design between vehicle models. Seven cars were tested in a climate chamber. The best cars operated down to 8°C below fuel's CFPP but the worst get into problems 5°C above CFPP with the same fuel. It is challenging to define what CFPP is needed in order to guarantee trouble-free winter performance because there are big differences between car models. It is fundamental to get the fuel temperature of a vehicle's fuel filter above the fuel's cloud point during driving, and this depends on fuel system design factors, such as location and size of fuel filter and fuel heater if it is used.

The Technical Research Centre of Finland has carried out tests evaluating the emission performance (regulated and unregulated) of alternative fuels for light-duty applications for the International Energy Agency (IEA). Several technologies were tested under varying environmental conditions using the same methodology. Altogether 14 light-duty vehicles on gasoline, diesel, alcohol and gaseous fuels were tested, and the number of test combinations (vehicles/fuels/temperatures) was 143. The differences between all fuel alternatives using three-way catalyst (TWC) technology (and also diesel) are rather limited. However, when temperature is lowered and also unregulated emissions are considered, the situation changes somewhat. The gaseous fuels come out as winners giving by far the lowest overall emissions.

In a diesel engine, both physical and chemical properties of the fuel affect exhaust emissions. This study focused on the separation of some physical and chemical effects of the fuel on the NOx emission. The tests were conducted with a bus engine using four diesel fuels with different density and aromatics levels. The measurements were performed using five injection timing settings to screen the effects of changes in actual injection timing. When conventional diesel fuel was replaced by reformulated diesel, NOx was reduced 7-13 %. Changes in the injection timing due to differences in the physical properties accounted only for a minor part (10-25 % relative) of the total reduction of NOx, whereas the greater part of the reduction (75-90 % relative) was due to other reasons, mainly fuel chemical properties.

Hydrotreated vegetable oil (HVO) named NExBTL is a 2nd generation renewable diesel fuel made by a refinery-based process converting vegetable oils to paraffins. Also animal fats are suitable for feedstocks. Properties of this non-ester type biobased fuel are very similar to GTL. It contains no sulfur, oxygen, nitrogen or aromatics. Cetane number is very high (∼90). Cloud point can be adjusted by severity of the process from -5 to -30°C, heating value is similar to diesel fuel, storage stability is good, and water solubility is low. Emissions of two heavy duty engines and two city buses are presented with HVO and sulfur free EN 590 diesel fuel. The effect of HVO on regulated emissions compared to EN 590 fuel was: NOx -7 % … -14 % PM -28 % … -46 % CO -5 % … -78 % HC 0 % … -48 % Aldehydes, PAHs, mutagenicity and particulate size were also measured.

The purpose of our study was to investigate the effects of TAME and heavier ethers on reformulated gasoline. The research work focused on the comparison of Californian Phase 2 gasoline (CARB), current Finnish reformulated gasoline containing MTBE (RFG1), or MTBE+TAME+heavier ethers (RFG2) with non-oxygenated Eurograde gasoline (EN228). Significant reductions in exhaust emissions were achieved with all reformulated fuels when compared to the Eurograde fuel. For instance, benzene emissions were reduced as much as 40 to 50 % for all cars at two temperatures and the emissions of total toxics were reduced by 14 to 45 % depending on vehicle type and temperature. The lowest 1,3-butadiene emissions were achieved with CARB gasoline. The amount of PAH compounds in the particulate matter from the non-catalyst vehicle was lower with the reformulated fuels than with the Eurograde fuel.

Effect of fuel reformulation (aromatics from 35 to 20 vol-%, sulfur from 0.05 to 0.005 wt-%) on exhaust emissions was measured from a car using ECE/EUDC tests. 14 PAHs, mutagenicity by Ames test and DNA adducts by using 32P-postlabeling were measured from the particulate soluble organic fraction (SOF). PAH-derived DNA adducts were measured in calf thymus DNA and human breast cancer MCF-7 cell line. Ames test and DNA adduct test measure the genotoxicity and metabolically activated PAHs in exhaust particulate SOF. PAHs, mutagenicity and DNA adducts were clearly reduced in SOF, which is a benefit caused by fuel reformulation.

Electrical low pressure impactor ELPI was modified to measure particles below 30 nanometers in aerodynamic diameter. This was accomplished by adding a filter stage to collect and measure nanoparticles. The charging unit of the instrument was modified to increase the charging efficiency of the smallest, nanometer sized, particles. The modified charging unit was calibrated and the new construction of the ELPI was tested in laboratory and in vehicle dynamometer test cell. Measurements performed in the engine test cell showed that modifications improve the size range and measurement capability of the ELPI for engine emissions.

New method to define the particle effective density as a function of particle size has been applied to diesel vehicle exhaust particles. The results show that, the effective density of agglomerated diesel particles decreases as a function of particle size. The density of primary particles varies from 1.1 to 1.2 g/cm3. Also the effect of used dilution method and fuel type on particle density was studied. The dilution effect seems to have stronger effect on particle effective density and structure than the fuel type.

Because of the great interest in biodiesel fuels around the world, the International Energy Agency's 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 (UVOME) in 30% blend, and the Swedish environmental class 1 reformulated diesel (RFD).

Cold operating environment has many kinds of negative effects on the use of automobiles. Low ambient temperature degrades start-up performance and increases fuel consumption. Hence, the amount of harmful exhaust emissions is also elevated. In particular, high concentrations of carbon monoxide (CO) and unburned hydrocarbons (HC) are present. The continuously widening implementation of US-type emission regulations around the world has brought emission control technology based on the use of three-way catalyst (TWC) even to the Nordic countries having cold climate. Cold-start increases emissions from conventional cars, and especially the performance of TWC type of emission reduction has been shown to be quite susceptible to low ambient temperature. Therefore, an increasing emphasis has been set to the testing of exhaust emissions also at sub-normal temperatures, i.e. below the range of +20 …+30°C widely designated by the legislative procedures.

When a new type of fuel is introduced, it is necessary to ensure that exhaust gas aftertreatment systems work properly with these fuels. Today diesel particulate filter (DPF) is an inherent part of current diesel engine's exhaust gas aftertreatment system due to stringent exhaust emission limits. The functioning of DPF depends on the composition of soot particulates of exhaust gas, whereas the type of soot depends on the fuel used. To avoid clogging, DPF has to be regenerated regularly. This regeneration is usually increasing fuel consumption, so the longer the regeneration interval is, the better is fuel economy. Fuel quality and engine-out particulate emissions are important factors affecting to the need of regeneration. Renewable fuels burn cleanly and produce less particulate emissions than ordinary diesel fuel. Therefore, the increase of exhaust backpressure is slower enabling longer regeneration frequency.

When switching from regular diesel fuel (sulfur free) to paraffinic hydrotreated vegetable oil (HVO), the changes in fuel chemistry and physical properties will affect emission characteristics in a very positive way. The effects also depend on the technology, after-treatment and sophistication of the engine. To determine the real effects in the case of city buses, 17 typical buses, representing emission classes from Euro II to EEV, were measured with HVO, regular diesel and several blended fuels. The average reduction was 10% for nitrogen oxides (NOx) and 30% for particulate matter (PM). Also some engine tests were performed to demonstrate the potential for additional performance benefits when fuel injection timing was optimized for HVO.

Emissions of heavy duty engines using hydrocarbon fuels and rape seed methyl ester (RME) were measured according to the ECE R49 test procedure. The effect of fuel density on engine power was taken into account in the ECE R49 tests. The two reformulated fuels tested had sulphur below 50 ppm, aromatics below 20 vol-%, cetane number over 49 and reduced triaromatic content. Particulates were measured in a AVL Mini Dilution Tunnel 474 and gaseous unregulated hydrocarbons by Siemens FTIR. Reformulation reduced NOx by 5 to 12 %, particulates by 10 to 25 % and Ames mutagenicity by 56 to 74 %. RME increased NOx by 4 to 9 %, reduced particulates by 0 to 33 % and the mutagenicity by 17 %. Cetane number was found to be not important in reducing emissions. Low fuel triaromatic and low particulate PAH content reduced the mutagenicity of particulates.

Diesel fork-lifts are often preferred over LPG due to lower costs and superior fire safety in in-door use but exhaust causes problems. Air quality was measured with standard and reformulated diesel fuel in a warehouse where diesel fork-lifts operated. Sulphur was 605 ppm for the standard and 7 ppm for the reformulated fuel. Aromatics were respectively 31 vol-% and 12 vol-% and 95-% distillation points 352 °C and 286 °C. Fuel reformulation reduced particulates in the ware-house air by 40 %, particulate SOF by 50 % and mutagenicity of SOF by 80 %. NO, NO2, SO2 and PAH concentrations were low. Irritation and the possibility of long-term health problems reduced.

Unregulated emissions of reformulated diesel fuels (sulfur < 50 ppm, aromatics < 20 vol-%) were compared to the European EN590 specification fuel (sulfur < 500 ppm, aromatics < 35 vol-%) in three IDI passenger cars and one DI van using FTP and/or ECE/EUDC emission test procedures. The effect of reformulated diesel fuels on the mutagenicity of particulate soluble organic fraction (SOF) was studied. Fuel reformulation reduced particulate emissions in IDI cars. Reformulating fuel by decreasing heavier aromatics - without decreasing final boiling point - reduced particulate mutagenicity on emission basis. At low ambient temperature (-7°C) particulate PAH and mutagenic emissions increased compared to the standard ambient temperature (+22°C) with all fuels.

Diesel fuel was reformulated by reducing sulfur to < 0.005 wt-%, aromatics to < 20 vol-% and by limiting heavy polyaromatics. This reduced NOx, particulate, PAH and mutagenic emissions plus exhaust odor. Oxidation catalysts operated well. Less deposits formed in the EGR system. Fuel lubricity was enhanced by additives evaluated by injection pump tests and HFRR. Three years of field testing with 140 buses showed no fuel related problems. Oil change period could be lengthened and fuel consumption was unchanged. Demand for reformulated fuel was triggered by differentiating taxation based on quality. Fuels have been used since 1993 without problems. Life cycle analysis showed no increase of CO2.

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.

Diesel fuels must have good flow properties at low ambient temperatures. These fuels have lower densities than normal fuels. Fuel-injection pumps work on the basis of volume, and thus the fuel mass flow is reduced by density decrease. This leads to lower engine power. In Finland, for instance, the engine power reduction is about 10% when the fuel is changed from summer grade to arctic winter grade. The problem could be solved in future by using fuel density sensors in electronically governed injection pumps or by using fuel heaters so that vehicles could run on high density fuels also in winter.

Exhaust emissions from cars using reformulated gasoline (RFG) that meets European 2005 regulations for gasoline quality were compared to the emissions from cars using gasoline that meets European 2000 regulations (EU2000). Methyl Tertiary Butyl Ether (MTBE) and Tertiary Amyl Methyl Ether (TAME) were used as oxygenates in the reformulated gasoline. The EU2000 gasoline contained no oxygen. Regulated, particulate and PAH exhaust emissions were measured at 22°C for 7 cars and at -7°C for 5 cars using the European MVEG cycle for year 2000 (ECE+EUDC). One of the cars was equipped with a lean burn engine, one with a direct injection engine and one was a carburetor equipped car without a catalytic converter. All other cars were equipped with multi point port fuel injection and a catalytic converter. Mutagenic activity of particulate mass was evaluated using the Ames test.

Hydrotreating of vegetable oils or animal fats is an alternative process to esterification for producing biobased diesel fuels. Hydrotreated products are also called renewable diesel fuels. Hydrotreated vegetable oils (HVO) do not have the detrimental effects of ester-type biodiesel fuels, like increased NOx emission, deposit formation, storage stability problems, more rapid aging of engine oil or poor cold properties. HVOs are straight chain paraffinic hydrocarbons that are free of aromatics, oxygen and sulfur and have high cetane numbers. In this paper, NOx - particulate emission trade-off and NOx - fuel consumption trade-off are studied using different fuel injection timings in a turbocharged charge air cooled common rail heavy duty diesel engine. Tested fuels were sulfur free diesel fuel, neat HVO, and a 30% HVO + 70% diesel fuel blend. The study shows that there is potential for optimizing engine settings together with enhanced fuel composition.