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Since 2013, Euro VI heavy-duty on-road vehicles have been on the market in the Europe. Regulated exhaust emissions, including nitrogen oxides and particulate matter, have been cut down to a very low level, independent of fuel (diesel or natural gas). Multiple research papers have shown that the regulated emissions from the Euro VI and US 2010 heavy-duty on-road vehicles tested on chassis dynamometers really deliver emission levels which correspond the type approval requirements, independent of the test cycle used. In-service conformity (ISC), which is included in the Euro VI legislation, requires heavy-duty on-road engine manufacturers to test and prove their engines to comply with the emission legislation during the engine in-use period. The measurements are carried out in the field using PEMS (Portable Emission Measurement System) equipment. This kind of testing, depicting real-world emissions is the final stage to confirm low real-life emissions.

The Finnish pulp and paper company, UPM, will start a biorefinery in Finland in 2014 to produce advanced renewable diesel in commercial scale. The fuel production is based on using crude tall oil (CTO), a wood-based residue of pulping process, as a raw material. The end product, CTO based renewable diesel called UPM BioVerno, is a novel high quality drop-in diesel fuel resembling fossil diesel. It reduces greenhouse gas emissions by up to 80 % when compared to fossil fuels. In this study, the CTO renewable diesel was studied as a blending component in regular mineral-oil based fossil diesel fuel in field testing. The functionality and performance of four (4) passenger cars was evaluated by comparing e.g. fuel consumption and exhaust emissions of CTO renewable diesel blend (R20UPM) with fossil reference fuel. The field test included 20.000 km on-road driving with each car by experienced drivers from VTT Technical Research Centre of Finland.

In 2009 - 2011, a comprehensive project on urban buses was carried out in cooperation with IEA's Implementing Agreements on Alternative Motor Fuels and Bioenergy, with input from additional IEA Implementing Agreements. The objective of the project was to generate unbiased and solid data for use by policy- and decision-makers responsible for public transport using buses. The project comprised four major parts: (1) a well-to-tank (WTT) assessment of alternative fuel pathways, (2) an assessment of bus end-use (tank-to-wheel, TTW) performance, (3) combining WTT and TTW data into well-to-wheel (WTW) data and (4) a cost assessment, including indirect as well as direct costs. Experts at Argonne National Laboratory, Natural Resources Canada and VTT worked on the WTT part. In the TTW part, Environment Canada and VTT generated emission and fuel consumption data by running 21 different buses on chassis dynamometers, generating data for some 180 combinations of vehicle, fuel and driving cycle.

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.

Helsinki Region Transport, Neste Oil, Proventia Emission Control and VTT Technical Research Centre of Finland carried out a 3.5 year PPP venture “OPTIBIO” to demonstrate the use of paraffinic renewable diesel (hydrotreated vegetable oil HVO) in city buses. The fleet test in Metropolitan Helsinki involving some 300 buses is the largest one in the world to demonstrate this new fuel. The fuels were a 30 % blend of renewable diesel and 100 % renewable diesel. This paper describes the overall set-up of the project, gives an overview of the emission results as well as presents experience from the field.

Major part of the research work on particulate emissions has been carried out at normal ambient temperature (about +23 °C). In real life, the average day temperatures, especially in the winter season, are far below the “normal” temperature of the exhaust emission test procedures. For many years, it has been obvious that the knowledge of the total particulate mass emissions is not enough. Quality of these particles, e.g. polyaromatic hydrocarbon content and mutagenicity, has been studied. Now there is also a need to gain more information on fine particles, which can penetrate lungs more easily. International Energy Agency's Committee on Advanced Motor Fuels sponsored this study of the possible effect of ambient temperature on particle emissions. Also aldehydes and speciated hydrocarbons were studied. Several different engine and fuel technologies were covered, including gaseous fuels and biodiesel. Research work focused on light-duty technologies.

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).

Effect of lubricant on particle emissions was studied using two heavy-duty diesel engines. Both particulate mass and particle number distribution were measured. Differences between lubricants were studied by dosing two percent of each lubricant (diesel engine oil) to diesel fuel. This arrangement was seen necessary to get clear differences between lubricants. The lubricant had a clear effect on particulate mass emissions. Two of the lubricants gave about the same emission as pure diesel fuel. The worst result was more than two times higher than without oil added to the fuel. The lubricants were all diesel engine oils with different base oils/additive package. Lubricant ash content presumably affects particulate mass. However, the difference in ash content between lubricants was no higher than 30%. Therefore, ash content can only partly explain the differences. The combustion characteristics and the sulphur content of the base oil are essential, too.

The emissions of heavy-duty engines have traditionally been measured in Europe by using steady-state engine dynamometer tests. However, several studies have proved that emissions of real stop-and-go driving are much higher than the steady-state results indicate. In this study, a mobile measurement system, located inside a vehicle, was utilized. The emissions and energy consumption of different gaseous fuel powered transit buses were measured by using two duty cycles, and the results were compared with diesel technology. The results indicated that NOX emissions of gaseous fuels were in the range of 30-90 % lower than diesel, depending on vehicle technology and fuel. However, energy consumption of gaseous fuels was found to be around 20-45 % higher than in the case of diesel.

Many standardized tests for evaluating fuel properties have originally been designed for screening straight-run hydrocarbon products. In the case of fuels blended with new components or treated with additives, the traditional test methods may give misleading results. The objective of the work was to evaluate the correlation between the results of standardized testing and of the real-life serviceability of new diesel fuel qualities. Combustion properties, properties affecting exhaust emissions, low-temperature performance and diesel fuel lubricity were studied. The test fuel matrix comprised of typical conventional hydrocarbon diesel fuels, low-emission hydrocarbon fuels, rapeseed and tall oil esters and ethanol-blended diesel fuels. The base fuels were blended with a cetane improver additive and some fuels also with a cold flow improver additive. Combustion and emission tests were carried out with a heavy-duty bus engine and a diesel passenger car.

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.

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.

Propane is considered to be a viable fuel alternative for low-emission heavy-duty vehicles in Finland. Natural gas and propane have roughly the same potential for reduced exhaust emissions. Since natural gas and propane are both imported fuels in Finland, there is no preference between these two fuels. Propane, however, is much more easy to distribute, refuel and store onboard the vehicle. This is why propane has received more attention than natural gas as an automotive fuel. Work to develop a low-emission propane fueled truck started back in 1988 with engine tests. The first prototype, a 17-ton SISU truck was built in 1990, and was operated until September 1992. This truck was equipped with a 7.4-liter Valmet-engine, a closed-loop controlled IMPCO-fuel system and a three-way catalytic converter (TWC). The experience with this propane fueled truck was good. The driveability was excellent, and both noise level and exhaust emissions were low.

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 amounts of exhaust emissions are also elevated. In particular, high concentrations of CO and HC are present in the exhaust. Cold-start derates especially the performance of a TWC type of emission reduction. Therefore, an increasing emphasis has been set to the testing of exhaust emissions even at sub-ambient temperatures, For this reason, US-EPA has recently revised US emission regulations by comprising an additional low ambient temperature (20°F = -7°C) test for CO emissions. Apart from the regulated components, other poisonous compounds have been detected from the exhausts, although usually in very small quantities, A cold-start may have an increasingly strong effect even to the emission of these substances.

This paper presents the results of a gasoline reformulation project carried out in Finland during 1991. The target was to evaluate MTBE and ETBE as gasoline components with respect to operability and exhaust emission performance. The oxygenated fuels contained 2 to 2.7 per cent oxygen by weight. The oxygenated fuels reduced exhaust emissions significantly at normal ambient temperature. For non-catalyst cars the reduction of CO was 15 to 30 % and the reduction of HC was approx. 5 %. For three way catalyst (TWC) cars the CO emission decrease varied from 0 to 10 % and HC approx. 10 %. The use of oxygenates reduced exhaust emissions also at low ambient temperature, but not as much as at normal temperature. Cold starting was quicker and cold driveability was better when oxygenated fuels were used.

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.

There is a strong request for heavy-duty gas engines in the Nordic countries for environmental reasons. Therefore, several research projects are going on. This paper describes two of them: a Finnish Sisu truck and a MAN bus, both operating in the city of Espoo, the hometown of the Technical Research Centre. The truck is equipped with a 7.4 litre Finnish Valmet 612 engine. The development work has included engine tests and tests with a vehicle in laboratory conditions. A 3,3 litre 3-cylinder engine was used for the engine tests. The engine runs on stoichiometric mixture, and has a three-way catalyst based on metal substrate. The engine was run on both methane (compr. ratio 12:1) and propane (compr. ratio 10:1). Emissions were extremely low with both fuels. In the European 13-mode test 0.4 g CO, 0.1 g HC and 0.1 g NOx per kWh were achieved. Peak thermal efficiency was 35 % for both fuels. Maximum mean effective pressure (BMEP) for a naturally aspirated engine is 9 - 9,5 bar.

When evaluating fuels and engine lubricants in respect of, for example, fuel economy, high accuracy is required. In any engine testing, the best accuracy and repeatability are obtained with a test engine installed in an engine dynamometer, and not in a car on a chassis dynamometer. At the Technical Research Centre of Finland, a special cold chamber suitable for engine and transmission component testing was built in 1985. The equipment consists of a 75 m3 cold chamber, a powerful cooling machinery, a computer-controlled engine dynamometer, a hydrostatic propulsion unit and a versatile data acquisition system. This paper describes the structure of the system (cold chamber, cooling machinery and its control system, engine and engine dynamometer installation, instrumentation). Special problems like controlling engine operation point during warm-up, handling of fuels, lubricants and batteries, and measuring fuel consumption without disturbing the fuel system are discussed.

A low ambient temperature increases wear and fuel consumption in vehicle engines. The startability of the engine and the start-up of lubrication are highly dependent on the type of engine oil (mineral, semisynthetic, synthetic), whereas fuel consumption depends more on the engine type and driving conditions. The research work in a special cold chamber equipped with a powerful cooling system has so far involved three gasoline engines and two diesel engines. One gasoline engine was also tested in combination with an all-mechanical transaxle. Tests were carried out within the temperature range of +20…−30 °C using different engine lubricants in order to evaluate both lubrication during the initial start-up and fuel consumption during a test period of 30 minutes. Engines were run under both constant and cyclic load. Effects of auxiliary electrical block and oil sump heaters were also studied.