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This study presents emission results measured with renewable and synthetic diesel fuels. Three engines and five city buses were studied. The efficiency of diesel oxidation catalyst combined to particle oxidation catalyst (POC®) was measured with two engines. The studied diesel fuels were EN590, FAME, HVO and GTL. In most cases all regulated emissions decreased with HVO and GTL fuels compared to conventional EN590 diesel fuel. With FAME, the NOx emissions were higher compared to EN590, but other emissions were reduced. Alternative fuels had a positive effect on emissions, which are considered harmful to human health.

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.

Over the past decade significant research and development activities have been invested in alternative fuels in order to reduce our dependency on fossil fuel sources and reduce CO₂ and local emissions from traffic. One result of these R&D efforts is paraffinic diesel fuels, which can be used with existing vehicle fleets and infrastructures. Paraffinic diesels also have other benefits compared to conventional diesels, for example, a very high cetane number and the lack of sulfur and aromatic compounds. These characteristics are beneficial in terms of exhaust gas emissions, something which has been demonstrated in numerous studies. The objective of this study was to develop low-emission combustion technologies for paraffinic renewable diesel in a compression ignition engine, and to study the possible benefits of oxygenated paraffinic diesel.

State-of-art light duty diesel vehicles and heavy duty diesel engines are utilized in studying the effect of a novel particle oxidation catalyst (POC®) on particle emission. In addition to the regulated particulate matter (PM) emission measurement, a real time mass emission and particle number size distribution measurements are utilized in testing. The results show that the particle oxidation catalyst can have a significant decreasing effect on the diesel exhaust particle emissions. For example, in light duty applications PM reductions of 55-61% were achieved over the New European Driving Cycle (NEDC) when using a POC of same size as the engine volume. The usage of a DOC in combination with the POC ensures proper regeneration of the POC substrate. The size distribution measurements revealed that the particle number collection efficiency for smaller particles i.e. the nanoparticles was very high, being close to 100 %.

The effect of crankcase lubricant on fuel consumption and engine exhaust emissions was investigated. Seven different lubricants were measured in a 9.6-liter bus engine, representing Euro 2 emission-level technology. The measurements were made using six different steady-state load conditions. In addition to fuel consumption measurements, gaseous and particle mass emissions and particle size distribution measurements were performed. The average difference between the worst and the best lubricant on fuel consumption was 1.6%. There was a clear correlation between the viscosity of the lubricant and the fuel consumption. Also, changes in total hydrocarbons and particle mass emissions occurred. The differences ranged between 0.6 to 22%.

In this study the exhaust gas ammonia (NH3) concentrations from different exhaust sources were measured with an ammonia sensor. The aim of the study was to verify whether an NH3 sensor has the potential to be used for monitoring and control purposes for SCR systems. Measurements were performed in laboratory and field conditions and comparison was made between Fourier Transform Infrared (FTIR) and Laser Diode Spectrometer (LDS) measurement techniques. With heavy-duty vehicles, a comparison between an LDS, FTIR and NH3 sensor was performed on a heavy-duty chassis dynamometer. Measurements were performed at steady speeds using a World Harmonized Vehicle Cycle (WHVC) and Braunschweig test cycles. The urea injection rate for the SCR system was varied to generate different ammonia levels in the exhaust gas. NH3 measurements with FTIR and NH3 sensor were performed on large cruise ships using heavy fuel oil (HFO) and marine gas oil (MGO) as fuels.