1. Assessing the effects of a hydropower plant basin on fish spawning in an upstream river tributaryGorazd Hren, Andrej Predin, Matej Fike, Marko Pezdevšek, 2024, izvirni znanstveni članek Opis: This paper presents a combined modeling approach to evaluate the ecological effects on the habitat of an upstream tributary of a river with a series of hydropower plants. The influence is investigated of the last planned hydropower plant to be built, which has a large impact on the river ecosystem. The new hydropower plant basin will affect the tributary with hydropeaking in the upstream basin. A simulation was conducted of spawning conditions for two protected fish species. The analysis combined a hydro-morphological model with a fish module that considers the water depth and velocity necessary for fish reproduction. The different river discharge scenarios were simulated, incorporating the hydropeaking effects of the new hydropower plant basin on the upstream tributary. With the new hydropower plant, sustainable measures are planned to prevent the damaging negative impacts that could lead to the degradation of the river ecosystem and the destruction of the existing ecosystem at the river’s confluence. The results indicate that, after the hydropower plant begins operation, the habitat`s suitability will decrease, and the planned sustainable measures will not provide a fully satisfactory solution.
Ključne besede: environmental impact, habitat sustainability, hydro-dynamic model
Objavljeno v DKUM: 11.04.2025; Ogledov: 0; Prenosov: 10
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2. Theoretical and experimental investigations of a water hammer in Sava river Kaplan turbine hydropower plantsAnton Bergant, Jernej Mazij, Jošt Pekolj, 2024, izvirni znanstveni članek Opis: This paper deals with critical flow regimes that may induce an unacceptable water hammer in the Sava River Kaplan turbine hydropower plants. The rigid water hammer model is introduced first. The computational results are then compared with the results of measurements in two distinct hydropower plants (HPP): (i) The refurbished and upgraded Medvode HPP, and (ii) The newest Brežice HPP. Comparisons of the computed and measured results are examined for normal operating regimes. The water hammer in the two power plants is controlled by appropriate adjustment of the wicket gates and runner blades closing/opening manoeuvres. The agreement between the computed and measured results is reasonable.
Ključne besede: hydropower plant, Kaplan turbine, Sava River, water hammer, validation
Objavljeno v DKUM: 11.04.2025; Ogledov: 0; Prenosov: 7
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3. Efficient Approximation Procedure for Magnetization Characteristics Used in Performance Analysis of Highly Saturated Electrical MachinesMiralem Hadžiselimović, Tine Marčič, Ivan Zagradišnik, 2024, izvirni znanstveni članek Opis: The analytical and especially the numerical calculations of the magnetic fields of highly saturated electrical machines require a correctly given magnetizing curve. In practice, professional software may use many points of the magnetizing curve (sometimes 50 or more points). There is a high probability that a point will be entered or measured incorrectly. We have therefore set ourselves three objectives. The first is to reduce the number of points given. The second is to ensure that the curve is given analytically (in the form of orthogonal polynomials) and is as smooth as possible. This means that the derivatives of the reluctance are also as smooth as possible. Therefore, the Newton– Raphson iteration procedure in numerical calculations converges rapidly. The third objective was to make the magnetizing curve continue beyond a magnetic field density of 2 T up to about 3 T. Most professional programs simply limit the magnetizing curve to about 2.2 T. This limitation makes it impossible to calculate accurately the magnetic field in the bridges, especially when the slots in the rotor are closed. Local fields can exceed values of 2.2 T. A solution has been found. It uses higher order orthogonal polynomials. It has been shown that 12 given points of the magnetizing curve is enough to give a good approximation of the measured curve. However, one polynomial function is not enough. We need three functions and another exponential function for magnetic field densities above around 2 T up to a value of relative permeability equal to 1. In the numerical calculation of the field, we thus achieve the desired error (residual) vector of the Newton–Raphson iterative procedure in 10 ÷ 15 steps for semi-closed slots and 20 ÷ 30 steps for closed slots.
Ključne besede: induction motors, magnetizing curves, numerical calculation
Objavljeno v DKUM: 10.04.2025; Ogledov: 0; Prenosov: 5
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4. Determination of neutron flux redistribution factors for a typical pressurized water reactor ex-core measurements using Monte Carlo techniqueTanja Goričanec, Bor Kos, Klemen Ambrožič, Andrej Trkov, Luka Snoj, Marjan Kromar, 2023, izvirni znanstveni članek Opis: In a typical pressurized water reactor, neutron detectors located outside the reactor core monitor reactor power. In addition, they are also used to measure the reactivity of the control rods. A novel approach to calculate the ex-core neutron detector response in a typical pressurized water reactor using the Monte Carlo technique is presented. A detailed ex-core model of the Krško nuclear power plant was developed using the Monte Carlo neutron transport code MCNP. Due to the location of the ex-core neutron detectors, the hybrid code ADVANTG is used to generate variance reduction parameters to accelerte the convergence of the results outside the reactor core. To use ADVANTG, the fixed neutron source had to be reconstructed from the criticality core calculation. This paper presents the sensitivity analysis of the response of the ex-core detectors to the neutron data libraries used, the description of the fixed neutron source and the ADVANTG parameters. It was found that a pin-wise description of the neutron source for at least two rows of fuel assemblies at the core periphery is necessary for accurate results. Our results show the importance of a correct description of the prompt neutron spectra in the high energy region and the impact this has on the response of the ex-core detectors. The method in which the prompt neutron fission spectra for important fission nuclides are weighted by the calculated reaction rates has been shown to be the best approximation, with deviations from the reference calculation within statistical uncertainty. The effect of nuclear data libraries on the response of the ex-core detector was investigated, and the difference between the ENDF/B-VII.0 and the ENDF/B-VIII.0 nuclear data libraries was ∼11%. When the deficient evaluation of the 56Fe isotope included in the ENDF/B-VIII.0 nuclear data library was replaced by the improved evaluation from the IAEA INDEN project, the differences decreased to ∼3.7%. In addition, neutron flux redistributions due to control rod movement were investigated and flux redistribution factors were updated using Monte Carlo particle transport methods. The reaction rate redistribution factors obtained with methods presented in this paper are within 1% agreement with the currently used factors.
Ključne besede: MCNP, ADVANTG, pressurized water reactor, Monte Carlo neutron transport, control rod, neutron flux redistribution factor, rod insertion, krško nuclear power plant
Objavljeno v DKUM: 29.11.2024; Ogledov: 0; Prenosov: 7
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5. 6th International Conference En-Re Energy & Responsibility : Book of Extended Abstracts2024 Opis: In the context of escalating climate challenges, the EnRe conference is dedicated to exploring pathways to climate neutrality and the sustainable green transition. The conference is focused on the development and implementation of innovations supporting the transformation of energy systems, industrial systems, and living systems, all with the goal of creating a sustainable future with net-zero emissions. The conference brings together experts, researchers, policymakers, and business leaders to share their experiences, research, and visions. The aim of the conference is to foster collaboration and exchange of ideas, and to collectively develop comprehensive approaches and strategies for achieving climate neutrality. This conference is not just a knowledge exchange, but also a platform for encouraging concrete actions that will ensure a greenerand more sustainable future for our next generations to come.
Ključne besede: alternative energy systems, dynamic tariffing, electrical machines and drives, energy conversions, financing energy projects, nuclear energy, conventional energy systems, climate changes - climate pan, mathematical methods in engineering, micro and nano energy, low-carbon technologies and strategies, renewable energy technologies heating and cooling systems, smart buildings, cities and networks, policies and strategies for renewable energy sources, energy efficiency and the climate
Objavljeno v DKUM: 17.05.2024; Ogledov: 332; Prenosov: 49
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6. Virtualni inženiring I : komponente virtualnega inženiringa, zapiski predavanjGorazd Hren, 2024 Opis: Zapiski predavanj so namenjeni študentom, ki se vsakodnevno in vedno bolj srečujejo z uporabo razvojnih računalniških orodij pri designu izdelkov. Izredno kakovostne in tudi kompleksnejše računalniške aplikacije omogočajo simulacije in analize inženirskih rešitev preden so te implementirane kot prototipi ali končni izdelki. Virtualni inženiring najprej tvorijo komponente za ustvarjanje geometrije, sistemi CAD in povratni inženiring s sistemi skeniranja, ki predstavlja osnovo za nadaljnje postopke razvoja izdelkov. Naslednje komponente so izdelava virtualnih prototipov v navideznem okolju ali fizičnih prototipov, katerih izdelava je dandanes večinoma izvedena s 3D tiskom. Izrednega pomena v razvoju izdelkov so numerične simulacije, ki omogočajo analize -trdnosti, dinamike tekočin in gibanja mehanizmov - glede na robne pogoje. S pridobljenimi podatki lahko načrtujemo proizvodnjo, logistiko, kontrolo kakovosti, ergonomijo, marketing, preden gre izdelek v končno izdelavo. Vse te komponente povezujejo informacijski sistemi DMU, PLM, ki omogočajo in tudi določajo organizacijsko strukturo razvojnega dela, opisanem v zadnjem poglavju: Virtualni razvoj izdelkov.
Ključne besede: virtualni inženiring, sistemi CAD, povratni inženiring, numerične simulacije, virtualni razvoj izdelkov
Objavljeno v DKUM: 10.05.2024; Ogledov: 366; Prenosov: 49
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7. Current control of battery pack modules in parallel connection according to SoCMario Vražić, Antonio Persic, Peter Virtič, Tomislav Ivanis, 2023, izvirni znanstveni članek Opis: Electric vehicles, especially cars, have been in the spotlight for some time now. In the focus of environmentalists, engineers, users, media, etc. With the growth and advancement of the market for such vehicles, other electric vehicles are also focussing on. One of such vehicles is boats, particularly smaller boats up to 8–10 meters in length. Of course, the biggest problem here is charging. The general idea is to use battery modules that can be easily carried and enable hot swapping. This paper investigates scenarios and simulations of the control system for hot swapping of the battery module. Simulations of connection of two and three battery modules to parallel operation and current control are presented in this paper, as well as applied control rules.
Ključne besede: battery pack, battery modules, parallel connection, Bidirectional multiple input single output synchronous DC/DC converter, BMISO DC/DC converter, Hotplugin, Smart SoC control, Advanced SoC control
Objavljeno v DKUM: 08.04.2024; Ogledov: 370; Prenosov: 20
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8. Numerical analysis of a wind turbine blade with different softwareGorazd Hren, 2019, izvirni znanstveni članek Opis: The development of wind power generation technology recognises the wind turbine blade design and manufacturing as crucial for its performance. The laboratory size wind turbine blade was analysed, considering the 3D printing plastic material for blades. Applying the structural dynamic equations of blades, the aero-elastic model of the rotating rotor and the numerical simulation method of the deflections are presented under the aerodynamic loads and centrifugal forces. Based on the parameters of aerofoil and the geometrical parameters of blade, 3D model of the blade was established with the modelling software. Then the model was introduced into computational flow dynamics software to carry out the loads on the blade and further into numerical structural analysis. The analysis was performed in two different software packages. Design of wind turbine blades depends on high precision, reliable and robust numerical predictions of performance where the plug-in software is found to be inadequate for nontrivial problems.
Ključne besede: computational fluid dynamics, numerical analysis, structural analysis, wind turbine blade
Objavljeno v DKUM: 22.02.2024; Ogledov: 332; Prenosov: 56
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9. Evaluation of system for economically viable thermal power plant operationMartin Bricl, Jurij Avsec, 2019, izvirni znanstveni članek Opis: Taking into consideration the impacts of global warming and strict European Union policy 2030 climate & energy framework, it is imminent for conventional thermal power plants to modernize their infrastructure for achieving economically viable operation on demanding electricity market. In the scope of the paper is presented author%s individual research work - economic evaluation of conventional thermal power plant operation with solar central receiver system and flue gas desulphurization installation. The goal of research work is to determine whether the designed model is profitable on current European electricity market or not. Based on analytical calculations and gathered numerical data for the designed model, a program code was generated in mathematical environment Matlab, that enables simulation of operation for the designed model in the annual time period. Positive and pessimistic scenarios were analyzed. Results are presented numerically and also graphically and show a positive contribution to the economically viable operation of conventional thermal power plants.
Ključne besede: thermal power plant, economically viable operation, a solar central receiver system, renewable technologies, flue gas desulphurization
Objavljeno v DKUM: 22.02.2024; Ogledov: 360; Prenosov: 21
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10. Application of gas condensing boilers in domestic heatingMarija Živić, Antun Galović, Jurij Avsec, Antun Barac, 2019, izvirni znanstveni članek Opis: A growing number of households have had condensing boilers built in to be used for the heating of spaces and for the hot water supply. The use of condensing boilers is justified from the point of view of energy because they achieve higher thermal efficiency than traditional boilers. Condensation of water vapour occurs in the flue gases, whereby the heat released by condensation is used to heat the water in the boiler. How much water vapour will condense depends on the temperature to which the flue gases are cooled. In this paper, a thermodynamic analysis of thirteen built-in gas condensing boilers was performed; data on the flue gas composition and temperature, as well as on the excess air required for combustion were obtained for that purpose. The calculation results consisting of the amount of condensed water, the thermal efficiency of the boiler, and the volume flow rates of the air and fuel are presented in tables. The analysis identified the cases in which the water vapour condensation occurred and determined the amount of the condensed water. The cases without water vapour condensation were also identified.
Ključne besede: gas condensing boilers, thermodynamic analysis, thermal efficiency of the boiler
Objavljeno v DKUM: 22.02.2024; Ogledov: 281; Prenosov: 26
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