No abstract

Unstable oil markets combined with the alarming statistics of continuously growing emission problems causes anxiety among many nations. The greatest dilemma lies in the answer about how to rationally overcome the dependency of fossil based energy sources. The truth seems to be found on utilizing renewable energy generating low emissions. Methane is suggested as one of the worthwhile solutions for substituting crude-oil based fuels. Methane as a fuel combined with modern engine technology seems to open possibilities solving the above mentioned problems.Dual-fuel technology is suggested as a solution for effectively utilizing alternative fuels in the near future. Charge air mixed methane combined with a compression ignition engine utilizing a small diesel pilot injection seems to form a worthwhile compromise between good engine efficiency and low emission outcome. Problems concerning dual-fuel technology profitableness seems to be related to fully control the combustion in relation to lean conditions. Lean operating conditions solves the problems concerning pumping losses, but brings challenges in controlling the slow heat release of the premixed methane.A study concerning lean operation dual-fuel combustion was executed. In the thesis, a single cylinder 'free parameter' diesel engine was adapted for dual-fuel (diesel-methane) usage. A parameter research related to lambda window widening possibilities was carried out. The main variables studied were diesel pilot injection timing and pressure, diesel substitution rate and the relation between combustion characteristics and charge air temperature.Diesel pilot injection parameter optimization seems to affect less on combustion quality compared to the benefits from increasing the charge mass reactivity through preheating the charge air. Improvements in combustion quality were noted in all lean condition tests in the diesel substitution rate scale 0 -70%. However, significant variation in combustion characteristics were noted through the whole substitution rate range. Remarkable accomplishments in combustion behavior were experienced in the misfire boundary conditions in a form of premixed mixture ignition in the end gas region (PREMIER).Keywords dual-fuel, methane fuel, combustion character TiivistelmäÖljymarkkinoiden epävarmat ennusteet sekä jatkuvasti kohoavat päästöt aiheuttavat maailmanlaajuista huolta tulevaisuuden kannalta. Suurimmat kysymykset ongelmatilanteeseen liittyvät fossiilisten raakaöljyjen korvaamismahdollisuuksiin. Ratkaisu vaikuttaisi löytyvän uusiutuvista, matalia päästöarvoja tuottavista energianlähteistä. Yhdeksi kannattavaksi raakaöljyn korvaajaksi on ehdotettu metaanikaasua. Ennusteet metaanikaasun eduista yhdistettynä modernien polttomoottorien kanssa enteilevät mahdollisuuksia ongelmien ratkaisemiseksi.Dual-fuel-teknologia on esitetty hyväksi moottorityypiksi hyödyntämään uusiutuvia energianlähteitä. Imuilmaan esisekoitettu metaanikaasu yhdistettynä puristussytytteisen polttomoottorin kanssa, jossa polttoaine-seoksen syttymistä sekä p...

Reduced emissions and environmental burden from shipping are an important aim of tightening emission regulations and ambitious climate change strategy. Renewable methanol produced from biomass or from other renewable sources represents one option to face these challenges. We studied the potential of renewable methanol to offer such benefits in diesel operation in a Scania ethanol engine, which is designed for additized ethanol fuel (ED95) containing ignition improver and lubricity additives. Methanol (MD95) with several types of ignition improver and lubricity additives was studied for use in diesel engines. MD95 fuels were clean-burning, emitting even less gaseous emissions than ED95, particularly when glycerol ethoxylate was used as an ignition improver. Particle mass and number emissions originating from additives in the experimental fuels could be reduced with an oxidation catalyst. Reduced additive dosing in the MD95 fuels was studied with the aid of fuel injection into the intake manifold. Overall, the results showed that the monofuel MD95 concept is a promising solution for smaller vessels equipped with 800−1200 kW engines.

Substantial advances in European road vehicle emissions have been achieved over the past three decades driven by strengthening revisions in emissions legislation and enabled by advances in fuel, vehicle engine and emissions control technologies. As both vehicle technology and emissions legislation in Europe continue to evolve, Concawe has conducted a study to examine the effects that fuels can have on emissions, in this case from commercial road vehicles. A bus certified to Euro VI emissions level and a delivery truck certified to Euro V emissions level have been tested on a chassis-dyno over the World Harmonized Vehicle Cycle (WHVC) and Transport for London Urban Inter-Peak (TfL UIP) test cycles with six fuels: an EN590-compliant B5 (petroleum diesel containing 5% biodiesel by volume), a bioderived paraffinic diesel, a 50:50 blend of the aforementioned fuels, a low-density petroleum-derived B5, a B30 and the same B30 additized with a high dose of cetane number improver (CNI). Results show reduced NOx reductant (AdBlue) consumption with paraffinic diesel in the Euro VI bus due to lower engine-out NOx emissions. More surprisingly, higher hydrocarbon emissions were observed with some low-density hydrocarbon fuels in the Euro V truck. Compared to B5, B30 with and without CNI did not affect tank-to-wheel (TTW) CO2, volumetric fuel consumption or NOx by statistically significant margins. When considered with the findings of a complementary light-duty study, it is apparent that low-density diesel fuels could offer overall benefits to both emissions affecting local air quality and to greenhouse gas emissions on a TTW basis. The addition of higher fatty acid methyl ester (FAME) levels to fuels can be used to increase renewable fuel contribution resulting in no penalty in NOx emissions from modern technology vehicles. Compatibility of these fuels with the existing vehicle fleet would require further specific consideration. Outside of fuel properties considerations, Euro VI aftertreatment systems can increase N2O emissions at the tailpipe through chemical reactions in the catalyst. This can translate into about 10% contribution of N2O emissions to the overall GHG emissions of the vehicle.

No abstract