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Does the development of alternative energy technologies allow for new forms of coopetition?
Ante Galich, Lutz Marz, 2012, izvirni znanstveni članek

Opis: The article at hand illustrates how new types of coopetition emerge in the transformation of large technical systems. It builds on the latest literature on coopetition and highlights diverse institutional arrangements for coopetition, their effects on the actual innovation and the potential benefits for the firms involved. In contrast to many incremental innovations, the transformation of large technical systems requires the cooperation of many diverse actors as various resources are needed. This does not only open up the opportunity of new private-private or public-private cooperations but also brings about various new forms of commonly performed practices.
Ključne besede: hydrogen and fuel cells, coopetition
Objavljeno: 29.11.2017; Ogledov: 563; Prenosov: 258
.pdf Celotno besedilo (807,73 KB)
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Experimental investigation review of biodiesel usage in bus diesel engine
Breda Kegl, Marko Kegl, 2017, izvirni znanstveni članek

Opis: This paper assembles and analyses extensive experimental research work conducted for several years in relation to biodiesel usage in a MAN bus Diesel engine with M injection system. At first the most important properties of the actually used neat rapeseed biodiesel fuel and its blends with mineral diesel are discussed and compared to that of mineral diesel. Then the injection, fuel spray, and engine characteristics for various considered fuel blends are compared at various ambient conditions, with special emphasis on the influence of low temperature on fueling. Furthermore, for each tested fuel the optimal injection pump timing is determined. The obtained optimal injection pump timings for individual fuels are then used to determine and discuss the most important injection and combustion characteristics, engine performance, as well as the emission, economy, and tribology characteristics of the engine at all modes of emission test cycles test. The results show that for each tested fuel it is possible to find the optimized injection pump timing, which enables acceptable engine characteristics at all modes of the emission test cycles test.
Ključne besede: bus diesel engine, fuel injection, fuel spray, combustion, emission, engine performance, tribology characteristics, optimized injection pump timing
Objavljeno: 07.07.2017; Ogledov: 840; Prenosov: 331
.pdf Celotno besedilo (3,81 MB)
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Reactivation system for proton-exchange membrane fuel-cells
Carlos Restrepo, Oriol Avino, Javier Calvente, Alfonzo Romero, Miro Milanovič, Roberto Giral, 2012, izvirni znanstveni članek

Opis: In recent years, Proton-Exchange Membrane Fuel Cells (PEMFCs) have been the focus of very intensive researches. Manufacturers of these alternative power sources propose a rejuvenation sequence after the FC has been operating at high power for a certain period of time. These rejuvenation methods could be not appropriate for the reactivation of the FC when it has been out of operation for a long period of time or after it has been repaired. Since the developed reactivation system monitors temperature, current, and the cell voltages of the stack, it could be also useful for the diagnostic and repairing processes. The limited number of published contributions suggests that systems developing reactivation techniques are an open research field. In this paper, an automated system for reactivating PEMFCs and results of experimental testing are presented.
Ključne besede: reactivation system, PEM fuel cell, automated system
Objavljeno: 21.06.2017; Ogledov: 741; Prenosov: 287
.pdf Celotno besedilo (789,13 KB)
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The practical CFIE match to power articulated truck engines
Anton Černej, Želimir Dobovišek, Breda Kegl, 1996, izvirni znanstveni članek

Opis: 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.
Ključne besede: Diesel engines, fuel injection, trucks
Objavljeno: 06.06.2017; Ogledov: 787; Prenosov: 80
.pdf Celotno besedilo (1,72 MB)
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Solar powered transport solution
Matjaž Knez, Ali Naci Celik, Tariq Muneer, 2013, strokovni članek

Opis: Fossil-fuel based transport poses two chief problems - local and global pollution, and dwindling supplies and ever increasing costs. An elegant solution is to gradually replace the present automobile fleet with electric vehicles (EVs). This article explores the economics and practical viability of the provision of solar electricity for the charging of EVs by installation of economical available PV modules. A steep decline in the module, inverter and installation costs is reported herein. Present estimates indicate that for the prevailing solar climate of Celje - a medium-sized Slovenian town - the cost would be only 2.11 EUR cents/kWh of generated solar electricity.
Ključne besede: energy consumption, fuel consumption
Objavljeno: 10.07.2015; Ogledov: 4498; Prenosov: 25
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Biodiesel usage at low temperature
Breda Kegl, 2008, izvirni znanstveni članek

Ključne besede: internal combustion engines, buses, biodiesel fuel, rapeseed oil, fuel injection system, low temperatures
Objavljeno: 01.06.2012; Ogledov: 1210; Prenosov: 83
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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, izvirni znanstveni članek

Opis: 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.
Ključne besede: internal combustion engines, fuel injection, simulations
Objavljeno: 01.06.2012; Ogledov: 1216; Prenosov: 77
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Comparative study of various renewable fuels blends to run a diesel power plant
Eloisa Torres Jiménez, Marta Svoljšak, Andreja Gregorc, M. P. Dorado, Breda Kegl, 2010, objavljeni znanstveni prispevek na konferenci

Opis: In this paper bioethanol/diesel and bioethanol/biodiesel blends, at several concentrations and temperatures, are studied to find its possible commercial usage as a fuel to run a diesel power plant. The tested fuels were: net mineral diesel fuel (D100) , 5 % bioethanol/diesel fuel blend (v/v) (E5D95), 10 % bioethanol/diesel fuel blend (v/v) (E10D90), 15 % bioethanol/diesel fuel blend (v/v) (E15D85), neat biodiesel (B100), 5 % bioethanol/biodiesel blend (v/v) (E5B95), 10 % bioethanol/biodiesel blend (v/v) (E10B90), and 15 % bioethanol/biodiesel blend (v/v) (E15B85). The fuels were tested at: 30, 25, 8and -18 C. This paper shows the observations done in 8 samples during 5 weeks. After each week, each sample was overviewed, and changes related to stability, colour and aggregation were recorded. It has been proved that additives are not necessary to ensure stability of bioethanol/biodiesel blends under low temperature conditions, as the phase separation never happens.But in case of bioethanol/diesel blends some additives are necessary to keep stability under low temperature conditions. Based on this study, it can be concluded that blends of biodiesel fuel with bioethanol up to 15% can be used to fuel a diesel power plant if engine performance tests corroborate it. The same conclusion can be applied to blends of diesel fuel with bioethanol up to 15% blends if additives to keep stability are added.
Ključne besede: alternative fuel, biodiesel, bioethanol, heat engines, fuels blend
Objavljeno: 31.05.2012; Ogledov: 1292; Prenosov: 0

Influence of biodiesel on injection, fuel spray, and engine characteristics
Breda Kegl, Stanislav Pehan, 2008, izvirni znanstveni članek

Opis: 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.
Ključne besede: biodiesel, diesel engine, injection characteristics, fuel spray, emission, lubrication
Objavljeno: 31.05.2012; Ogledov: 1368; Prenosov: 281
.pdf Celotno besedilo (1,50 MB)
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Diesel and biodiesel fuel spray simulations
Primož Pogorevc, Breda Kegl, Leopold Škerget, 2008, izvirni znanstveni članek

Opis: This paper deals with the investigation of the influential parameters of a mathematical spray breakup model using different fuels. Beside injection system measurements, fuel physical properties and injection process characteristics were measured, because they are necessary for the spray simulation input. For validation purposes, spray was injected into motionless air at atmospheric pressure and room temperature and filmed with a high-speed camera. Spray macrocharacteristics have been determined on the recorded images. Using the simulation program, the injection processes for diesel, biodiesel, and their 50% blend B50 have been simulated. Spray mathematical model parameters were tuned based on the experimentally gained results. Primary breakup model parameters showed the biggest impact on the spray characteristics and were therefore expressed using the fuel physical properties, the injection process characteristics, and the working regime parameters. Spray simulations into the combustion chamber were made in the end. All of these results are presented and discussed in this paper.
Ključne besede: fuel spray, spray breakup, biodiesel fuel, fuels, numerical simulations, mathematical model
Objavljeno: 31.05.2012; Ogledov: 1307; Prenosov: 70
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