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1.
Performance and exhaust emissions of an indirect-injection (IDI) diesel enginewhen using waste cooking oil as fuel
Aleš Hribernik, Breda Kegl, 2009, original scientific article

Abstract: A study was carried out on the influence of waste cooking oil (WCO) and its blends with D2 fuel on the performance, exhaust emissions, combustion and fuel injection processes of an indirect injected diesel engine. Tests were carried out using different fuels, under the same conditions. Exhaust emissions and engine performance were measured and compared. Combustion chamber pressure was also acquired, and the rate of heat-release curves were computed by means of a zero-dimensional one-zone combustion model. Some macro-parameters of the combustion process were obtained from the heat-release-rate curves. The injection system was separated from the engine and tested on a special test bench. The injected fuel quantity was measured, and the injection pressure and injector needle lift time history were acquired. The injection-rate curves were then computed, and some macro-parameters of the injection process were obtained and analyzed.
Keywords: diesel engine, waste cooking oil, exhaust emissions
Published: 31.05.2012; Views: 914; Downloads: 43
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2.
Influence of biodiesel fuel on the combustion and emission formation in a direct injection (DI) Diesel engine
Aleš Hribernik, Breda Kegl, 2007, original scientific article

Abstract: This paper studies the influence of biodiesel fuel on the combustion and emission formation of two different direct-injected diesel engines, both employing different combustion processes. The research was focused on determining the influence of the specific combustion process on measurement results to ascertain if a generalization of the results is possible or whetherthey have to be interpreted as specific for specific engines. Standard D2 diesel fuel and commercial 100% biodiesel fuel were used. Tests were executed using both fuels under the same conditions, and exhaust emissions andengine performance were measured and compared. In-cylinder pressure was also acquired, and the rate of heat release curves were computed by means of azero-dimensional, one-zone combustion model. Some macroparameters of the combustion process were obtained from the heat-release-rate curves. The results obtained for both engines showed that findings regarding the influenceof biodiesel fuel on the combustion process and emission formation could not be generalized and had to be interpreted as specific for the particular engine.
Keywords: internal combustion engines, diesel engines, biodiesel fuel, combustion, emissions
Published: 31.05.2012; Views: 983; Downloads: 40
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3.
NOx and particulate matter (PM) emission reduction potential by biodiesel usage
Breda Kegl, 2007, original scientific article

Abstract: The transport in many countries is the most significant source for NOx and particulate matter (PM) emissions. Therefore, the possibility of reducing NOx and PM emissions is experimentally investigated using biodiesel and some of its blends with mineral diesel. Attention is focused on the optimal bus dieselengine adjustments for each tested fuel. The obtained engine characteristics are compared to each other by considering the 13 modes of the European stationary cycle test. The optimal injection pump timings are determined with the aim of reducing harmful emissions, while keeping other engine characteristics within acceptable limits. The optimal fuel blend is suggested, and the harmful emissions (NOx, PM, CO, unburned hydrocarbon, and smoke) reduction is estimated.
Keywords: internal combustion engine, NOx emissions, biodiesel fuel
Published: 31.05.2012; Views: 1011; Downloads: 27
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4.
CO2 separation from purge gas and flue gas in the methanol process, using NLP model optimization
Anita Kovač Kralj, Peter Glavič, 2007, original scientific article

Abstract: The concentration of CO2 in the atmosphere has to be stabilized, requiring a reduction in current emission rates in existing plants. This will be done by reducing the environmental burden imposed in such areas as materials input andCO2 emission reduction and using cleaner production, resources, and energy recycling. Any opportunities for emission reduction and CO2 reuse largely depend on existing plant and energy systems. CO2 can be separated from the outlet stream (purge gas) and from flue gas by a membrane or absorption system(absorber and regenerator) or adsorption system and reused as a reactantin a reactor system. Therefore, product yield can be increased and CO2emissions reduced, simultaneously. CO2 emissions can be reduced at the source. The authors of this paper studied CO2 reuse in a methanol process, in which electricity can be generated using an open gas turbine, followed by a separator. Simultaneous optimization of a process structure and its parametersusing simplified nonlinear programming (NLP) ensures an additional annual profit, influenced by reusing the flow rate of CO2. The additional electricity cogeneration and additional flow rates of the raw material could generate an additional profit of 2.79 MEUR/a.
Keywords: chemical processing, methanol production, optimization, nonlinear programming, CO2 emissions, CO2 reuse
Published: 31.05.2012; Views: 1200; Downloads: 47
URL Link to full text

5.
Effects of biodiesel on emissions of a bus diesel engine
Breda Kegl, 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 (D2) under various operating regimes. 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 D2. The obtained results are used to analyze the most important injection, fuel spray, and engine characteristics. The injection characteristics are determined numerically under the operating regimes, corresponding to the 13 mode ESC test. The fuel spray is obtained experimentally under peak torque condition. Engine characteristics are determined experimentally under 13 mode ESC test conditions. The results indicate that, by using biodiesel, harmful emissions (NOx, CO, smoke and HC) can be reduced to some extent by adjusting the injection pump timing properly.
Keywords: biodiesel, bus diesel engine, emissions
Published: 01.06.2012; Views: 655; Downloads: 42
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6.
Numerical and experimental study of water/oil emulsified fuel combustion in a diesel engine
Niko Samec, Breda Kegl, Robert W. Dibble, 2002, original scientific article

Abstract: Numerical and experimental studies were made on some of the chemical and physical properties of wateržoil emulsified fuel (W/OEF) combustion characteristics. Numerical investigations of W/OEF combustion's chemical kinetic aspects have been performed by simulation of water/n-heptane mixture combustion, assuming a model of a homogenous reactor's concentric shells. The injection and fuel spray characteristics are analyzed numerically also in order to study indirectly the physical effects of water present in diesel fuel during the combustion process. The experimental results of W/OEF combustion in the DI diesel engine are also presented and discussed. The results of engine testing in a broad field of engine loads and speeds have shown a significant pollutant emission reduction with no worsening of specific fuel consumption.
Keywords: internal combustion engines, Diesel engines, combustion, emissions, numerical modelling
Published: 01.06.2012; Views: 1187; Downloads: 60
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Acoustic noise emissions caused by transformer in a DC/DC converter for welding appliactaions [!]
Gorazd Štumberger, Klemen Deželak, Drago Dolinar, Beno Klopčič, 2012, published scientific conference contribution (invited lecture)

Abstract: This paper deals with the acoustic noise emissions caused by the transformer operating as a part of DC/DC converter in an industrial resistance spot welding system. The discussed DC/DC converter is schematically shown in Fig. 1. The three-phase alternating voltages (u1, u2 and u3) are rectified and smoothed in order to obtain almost constant DC-bus voltage UDC. The H-bridge inverter is used to supply the transformerćs primary winding with voltage pulses uH. The two transformerćs secondary windings are connected to the two output rectifier diodes (D1 and D2) which provide the direct welding current iL flowing through the load represented by LL and RL. A new control scheme forresistance spot welding systems was proposed in [1,2]. During the testing of the proposed control scheme it became evident that the proposed control scheme not only improves utilization of the iron core and prevent it from becoming saturated, but also substantially reduces the acoustic noise emissions caused by the transformer. The reasons for reduction of acoustic noise emission are discussed in this paper.
Keywords: DC/DC converter, acoustic noise emissions
Published: 10.07.2015; Views: 954; Downloads: 23
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10.
Innovative solution for energy efficient urban freight deliveries
Tomislav Letnik, Matej Mencinger, Stanislav Božičnik, 2017, published scientific conference contribution

Keywords: transport, urban freight, CO2 emissions, energy efficiency, fuzzy clustering
Published: 27.09.2017; Views: 338; Downloads: 42
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