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1.
Influence of biodiesel on injection, fuel spray, and engine characteristics
Breda Kegl, Stanislav Pehan, 2008, original scientific article

Abstract: This paper discusses the influence of biodiesel on the injection, spray, and engine characteristics with the aim to reduce harmful emissions. The considered engine is a bus diesel engine with injection M system. The injection, fuel spray, and engine characteristics, obtained with biodiesel, are compared to those obtained with mineral diesel under peak torque and ratedconditions. The considered fuel is neat biodiesel from rapeseed oil. Its density, viscosity, surface tension, and sound velocity are determined experimentally and compared to those of mineral diesel. The experimentally obtained results are used to analyze the most important injection, fuel spray, and engine characteristics. Furthermore, the influence of biodiesel usage on lubrication is presented briefly. The results indicate that, by using biodiesel, harmful emissions (NOx, CO, HC, smoke, and PM) can be reduced to some extent by adjusting the injection pump timing properly while keeping other engine characteristics within acceptable limits. Furthermore, the results indicate better lubrication conditions when biodiesel is used.
Keywords: biodiesel, diesel engine, injection characteristics, fuel spray, emission, lubrication
Published: 31.05.2012; Views: 1034; Downloads: 181
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2.
Experimental investigation of optimal timing of the Diesel engine injection pump using biodiesel fuel
Breda Kegl, 2006, original scientific article

Abstract: This paper discusses the influence of biodiesel on output characteristics of adiesel engine and optimal timing setup for its injection pump. The influence of biodiesel is studied by running experiments on an NA diesel bus engine MAN D2 2566 with a direct-injection M system. The fuel used is biodiesel produced from rapeseed. Special attention is focused on the determination of the optimal injection-pump timing with respect to engine harmful emissions, enginefuel consumption, and other engine performance parameters. These engine characteristics are compared against those obtained using conventional D2 diesel. Experiments with biodiesel and D2 are run on several engine operating regimes. The engine was monitored for possible operation problems and carefully examined after the tests. The results obtained are presented and analyzed. It is shown that with carefully optimized timing of the pump, the harmful emission of NOx, smoke, HC, and CO can be reduced essentially by keeping other engine characteristics within acceptable limits.
Keywords: internal combustion engines, diesel engines, fuel injection, biodiesel fuel, engine characeristics
Published: 31.05.2012; Views: 1361; Downloads: 52
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3.
Numerical analysis of injection characteristics using biodiesel fuel
Breda Kegl, 2006, original scientific article

Abstract: This paper deals with numerical analysis of injection process using biodieselžmineral diesel fuel blends with the aim to search for the potentialsto reduce engine harmful emissions. The considered fuels are neat biodiesel from rapeseed oil and its blends with mineral diesel D2. For the numerical analysis a one-dimensional mathematical model is employed. In order to model accurately the investigated fuels, the employed empirical expressionsfor their properties are determined by experiments. To verify the mathematical model and the empirical expressions, experiments and numerical simulation are run on a mechanical control diesel fuel injection M system at several operating regimes. Injection process at many different operating regimes and using several fuel blends are then investigated numerically. Attention is focused on the injection characteristics, especially on fuelling,fuelling at some stage of injection, mean injection rate, mean injection pressure, injection delay and injection timing, which influence the most important engine characteristics. The analysis of the obtained results reveals that, while keeping engine performance within acceptable limits, harmful emissions can be reduced by adjusting appropriately pump injection timing in dependence on the biodiesel content. This prediction is also confirmed experimentally.
Keywords: internal combustion engines, Diesel engines, fuel injection, biodiesel fuel, numerical simulation, emission reduction
Published: 31.05.2012; Views: 1182; Downloads: 62
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4.
Experimental analysis of injection characteristics using biodiesel fuel
Breda Kegl, Aleš Hribernik, 2006, original scientific article

Abstract: This paper deals with injection characteristics using different fuels at different fuel temperatures. The fuels under consideration are neat biodiesel from rapeseed oil and some blends with diesel as well as neat mineral diesel D2. The fuel and fuel temperature influences are investigated experimentally in the mechanically controlled diesel fuel injection M system. At first, attention is focused on the injection characteristics, especially on fuelling, mean injection rate, mean injection pressure, injection timing, injection delay, and injection duration, which influence the most important engine characteristics. Furthermore, the influence of fuel temperature is investigated. On the basis of the measurements of pressure drop through the fuel filter, the minimum fuel temperature for safe engine operation is determined.
Keywords: internal combustion engines, fuel blends, biodiesel fuel, temperature influence, injection characteristics
Published: 31.05.2012; Views: 1025; Downloads: 43
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5.
Optimization of a fuel injection system for diesel and biodiesel usage
Breda Kegl, Marko Kegl, Stanislav Pehan, 2008, original scientific article

Abstract: This paper presents an optimization procedure of a fuel injection system of a bus diesel engine. Attention is focused on the differences resulting from using two different types of fuel: diesel and biodiesel. The proposed design procedure relies on the assumption that the atomization of fuel spray influences the diesel engine performance, fuel consumption, and harmful emission significantly. As a measure of spray atomization, the Sauter mean diameter is employed and introduced into the objective function. The design problem is formulated in the form of a multiobjective optimization problem, taking into account the ESC 13 mode test for diesel engines of commercial vehicles. The design variables of the injection system are related to the shape of the cam profile, to the nozzle geometry, and to the control parameters influencing the injection quantity and timing. The geometrical properties of the cam profile and the injection parameters are kept within acceptable limits by the imposed constraints. The results of optimization using diesel and biodiesel are compared to each other to show the influence offuel type on final design and performance of the system.
Keywords: fuel injection system, diesel engine, biodiesel fuel, engine performance, numerical simulations
Published: 31.05.2012; Views: 1265; Downloads: 47
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6.
Tungsten - tungsten trioxide electrodes for the long-term monitoring of corrosion processes in highly alkaline media and concrete-based materials
Mitja Kolar, Aleš Doliška, Franc Švegl, Kurt Kalcher, 2010, original scientific article

Abstract: The determination of pH in highly alkaline solutions and concrete materials is extremely important for monitoring or predicting the corrosion processes of reinforced concrete structures and to follow the hydration process of Portland cement, fly-ash, micro silica and other materials used in concrete manufacturing. The corrosion of reinforced concrete structures and the hydration of pozzolanic materials are long-term processes, which means, that appropriate durable, and resilient pH electrodes are needed, for direct implantation regarding solid concrete bodies. The purpose of this work was to characterise the potentiometric and surface properties of tungsten electrodes after exposure to extreme alkaline solutions. The tungsten wire surface was activated at 800 °C for 30 min within an oxygen flow. The formation of homogenous and compact multiple layers of $WO_3$ crystals was observed using X-ray diffraction and scanning electron microscopy. X-ray diffraction of thosetungsten electrodes exposed to saturated calcium hydroxide solution or the pore-water of cement-based materials during 10 months, indicated partly dissolved $WO_3$. Two new compounds appeared on the electrodes surfaces; pure tungsten and $CaWO_4$. The presence of tungsten was affecting any potentiometric response in acidic pH region (2-5) but in pH 5-12 region the response still remained linear with a slope of 42 2 mV/pH unit. The $W/WO_3$ electrode was suitable for the long-term monitoring of corrosion processes in concrete-basedmaterials according to the pH changes as it has stable and repeatable responses to alkaline solutions (pH > 12). All the tested interferring ions had no significant influence on electrode potential. The $W/WO_3$ electrode is simple, robust, inexpensive, and temperature resistant and can be applied in potentiometric titrations as well as in batch and flow-injection analysis. The prepared electrode is a highly promising pH sensor for the monitoring of pH changes in highly alkaline capillary water of concrete.
Keywords: potentiometry, pH, tungsten - tungsten trioxide, pore water, concrete, flow-injection analysis
Published: 31.05.2012; Views: 1528; Downloads: 43
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7.
Coupled simulations of nozzle flow, primary fuel jet breakup, and spray formation
Eberhard von Berg, Wilfried Edelbauer, Aleš Alajbegović, Reinhard Tatschl, Martin Volmajer, Breda Kegl, Lionel C. Ganippa, 2005, original scientific article

Abstract: Presented are two approaches for coupled simulations of the injector flow withspray formation. In the first approach the two-fluid model is used within the injector for the cavitating flow. A primary breakup model is then applied at the nozzle orifice where it is coupled with the standard discrete droplet model. In the second approach the Eulerian multi-fluid model is applied for both the nozzle and spray regions. The developed primary breakup model, used in both approaches, is based on locally resolved properties of the cavitating nozzle flow across the orifice cross section. The model provides the initial droplet size and velocity distribution for the droplet parcels released from the surface of a coherent liquid core. The major feature of the predictions obtained with the model is a remarkable asymmetry of the spray. This asymmetryis in agreement with the recent observations at Chalmers University where they performed experiments using a transparent model scaled-up injector.The described model has been implemented into AVL FIRE computational fluid dynamics code which was used to obtain all the presented results.
Keywords: internal combustion engines, fuel injection, simulations
Published: 01.06.2012; Views: 877; Downloads: 52
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8.
Biodiesel usage at low temperature
Breda Kegl, 2008, original scientific article

Keywords: internal combustion engines, buses, biodiesel fuel, rapeseed oil, fuel injection system, low temperatures
Published: 01.06.2012; Views: 875; Downloads: 65
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9.
A numerical simulation of metal injection moulding
Boštjan Berginc, Miran Brezočnik, Zlatko Kampuš, Borivoj Šuštaršič, 2009, original scientific article

Abstract: Metal injection moulding (MIM) is already a well-established and promising technology for the mass production of small, complex, near-net-shape products. The dimensions and mechanical properties of MIM products are influenced by the feedstock characteristics, the process parameters of the injection moulding, as well as the debinding and the sintering. Numerical simulations are a very important feature of the beginning of any product or technology development. In the article two different techniques for measuring the rheological properties of MIM feedstocks are presented and compared. It was established that capillary rheometers are more appropriate for MIM feed stocks, while on the other hand, parallel-plate rheometers are only suitable for shear rates lower than 10 s[sup]{-1}. Later on we used genetic algorithms to determine the model coefficients for some numerical simulation software. The results of the simulation of the filling phase and a comparison with the experimental results are presented in the article.
Keywords: metal injection moulding, numerical simulation, genetic algorithms
Published: 14.03.2017; Views: 409; Downloads: 99
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10.
The practical CFIE match to power articulated truck engines
Anton Černej, Želimir Dobovišek, Breda Kegl, 1996, original scientific article

Abstract: Basic requirements related to fuel injection system of upgraded turbocharged articulated truck diesel engines are listed and discussed. An example of the FIE matching approach to upgrading of a heavy duty diesel engine is presented. The application of hollow cam fuel injection pump may offer a further extension of its use in order to uprate diesel engine performance.
Keywords: Diesel engines, fuel injection, trucks
Published: 06.06.2017; Views: 387; Downloads: 36
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