Effects of n-octanol as a fuel blend with biodiesel on diesel engine characteristics

Ordered porous silicates of the type TUD-1 and zeolite beta possessing zirconium and aluminium sites were evaluated as eco-friendly heterogeneous, multifunctional catalysts for the integrated reduction-acid conversion of furfural (Fur, industrially produced from hemicellulosic components of biomass) to useful bio-products, namely, furfuryl alcohol (FA), alkyl furfuryl ethers (FEs), alkyl levulinate esters (LEs), levulinic acid (LA), angelica lactones (AnLs), and γ-valerolactone (GVL); the bio-products spectrum was obtained by GC × GC-ToFMS. Carrying out the one-pot conversion of Fur to bio-products using a multifunctional catalyst is challenging since various reactions are involved and it is difficult to control all of these to meet high reaction efficiencies and selectivities. Aiming at designing improved multifunctional catalysts for this reaction system, the TUD-1 and zeolite beta type silicates possessing zirconium and aluminium sites in different ratios were prepared and characterised on microstructural and molecular levels. Systematic characterisation, catalytic testing using 2-butanol as dual functional solvent-H-donor, and kinetic modelling studies were performed using the Zr,Al-containing micro- and mesoporous materials. Different steps of the overall reaction of Fur were studied separately starting from intermediate products using the same materials, which helped understand the influence of the material properties on reactivity of intermediates and reaction selectivity. Zr-sites of the silicate catalysts were essential for effectively initialising the overall process (reduction of Fur to FA), and for the reduction of LEs to GVL; the co-presence of Al-sites promoted acid-catalysed steps (FA to FEs, LEs, AnLs, LA). The good stability of the catalysts was verified by catalytic and characterisation studies of the spent catalysts.

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Integrated reduction and acid-catalysed conversion of furfural in alcohol medium using Zr,Al-containing ordered micro/mesoporous silicates

Control strategies have been developed for hybrid electric vehicles (HEV) that minimize fuel consumption while satisfying a charge sustaining constraint. Since one of the components of an HEV is typically the ubiquitous internal combustion engine, tailpipe emissions must also be considered. This paper uses shortest-path stochastic dynamic programming (SP-SDP) to address the minimization of a weighted sum of fuel consumption and tailpipe emissions for an HEV equipped with a dual mode electrically variable transmission (EVT) and a catalytic converter. The shortest path formulation of SDP is chosen to directly address the charge sustaining requirement. Using simple methods, an SP-SDP solution required more than eight thousand hours. Using linear programming and duality, an SP-SDP problem is solved in about three hours on a desktop PC. The resulting time-invariant feedback controller reduces tailpipe emissions by more than 50% when compared to a popular baseline controller.

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SP-SDP for Fuel Consumption and Tailpipe Emissions Minimization in an EVT Hybrid

Today’s biofuels require large amounts of energy in the production process for the conversion from biomass into fuels with conventional properties. To reduce the amounts of energy needed, future fuels derived from biomass will have a molecular structure which is more similar to the respective feedstock. Butyl levulinate can be gained easily from levulinic acid which is produced by acid hydrolysis of cellulose. Thus, the Institute for Combustion Engines at RWTH Aachen University carried out a fuel investigation program to explore the potential of this biofuel compound, as a candidate for future compression ignition engines to reduce engine-out emissions while maintaining engine efficiency and an acceptable noise level. Previous investigations identified most desirable fuel properties like a reduced cetane number, an increased amount of oxygen content and a low boiling temperature for compression ignition engine conditions. Depending on the chain length, fuel compounds vary in cetane number and boiling temperature. Therefore different blends of butyl levulinate and n-tetradecane, a long-chain alkane, were investigated in this study. To gain knowledge about the combustion process with biofuels, experiments on a single cylinder diesel research engine were performed. Engine results with blends of butyl levulinate and n-tetradcanee are compared to regular diesel fuel and rapeseed oil methyl ester (B100) with respect to all regulated emissions. With the use of butyl levulinate the soot emissions can be significantly reduced up to 100 % depending on the load point. Furthermore, the experimental results indicate an additional potential for future diesel combustion concepts such as HCCI with respect to soot and NOx emissions in the part load range when using oxygenated fuels derived from biomass. Overall, the low particulate matter emissions provide justification for the consideration of butyl levulinate as a candidate for a fuel or fuel compound in future diesel engines. As a drawback malfunctions in various components of the fuel system like fuel hoses and fuel sealings can occur with the standard engine equipment.

Potential of Cellulose-Derived Biofuels for Soot Free Diesel Combustion

The impact of the operating strategy on emissions from the first combustion cycle during cranking was studied quantitatively in a production gasoline direct injection engine. A single injection early in the compression cycle after IVC gives the best tradeoff between HC, particulate mass (PM) and number (PN) emissions and net indicated effective pressure (NIMEP). Retarding the spark timing, it does not materially affect the HC emissions, but lowers the PM/PN emissions substantially. Increasing the injection pressure (at constant fuel mass) increases the NIMEP but also the PM/PN emissions.

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Effect of Operation Strategy on First Cycle CO, HC, and PM/PN Emissions in a GDI Engine

Spark Ignition Engine Hydrocarbon Emissions Behaviors in Stopping and Restarting

The primary aim of this study is to investigate current issues of combustion in high-speed direct-injection diesel engines in detail by optical diagnostics. Both fuel and engine design are considered. Recently, measurements of engine-out emissions demonstrated that approximately soot-free combustion can be achieved using a newly designed two-component fuel named BLT. It was composed of 70% butyl levulinate and 30% n-tetradecane (by volume). In this work, the underlying mechanism is clarified by in-cylinder visualization of OH* radicals and soot. In particular, it turns out that in-cylinder soot formation is avoided almost completely, that is, the soot oxidation process is much less important. This is basically achieved by both the oxygen content (about 21%) and the low cetane number (approximately 33) of BLT. The latter leads to enhanced pre-mixing of fuel and air. Consequently, soot formation can be greatly reduced because it depends on the air–fuel ratio of the mixture shortly before high-temperature co...

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Daniel Klein

Papers

Spark Ignition Engine Hydrocarbon Emissions Behaviors in Stopping and Restarting

Optical investigation of fuel and in-cylinder air-swirl effects in a high-speed direct-injection engine:

Mixture-Formation Analysis by PLIF in an HSDI Diesel Engine Using C8-Oxygenates as the Fuel

Laser-Induced Incandescence Measurements of Tailor-Made Fuels in an Optical Single-Cylinder Diesel Engine