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1.
An All-Fiber Fabry–Pérot Sensor for Emulsion Concentration Measurements
Simon Pevec, Janez Kunaver, Vedran Budinski, Matej Njegovec, Denis Đonlagić, 2023, izvirni znanstveni članek

Opis: This paper describes a Fabry-Perot sensor-based measuring system for measuring fluid composition in demanding industrial applications. The design of the sensor is based on a two-parametric sensor, which enables the simultaneous measurement of temperature and refractive index (RI). The system was tested under real industrial conditions, and enables temperature-compensated online measurement of emulsion concentration with a high resolution of 0.03 Brix. The measuring system was equipped with filtering of the emulsion and automatic cleaning of the sensor, which proved to be essential for successful implementation of a fiber optic RI sensor in machining emulsion monitoring applications.
Ključne besede: optical fiber sensors, Fabry–Pérot interferometer, refractive index, temperature, emulsion concentration
Objavljeno v DKUM: 06.02.2024; Ogledov: 74; Prenosov: 3
.pdf Celotno besedilo (4,44 MB)
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2.
Načrtovanje sistema vodenja termoelektričnega hladilnika
Alen Merčnik, 2023, diplomsko delo

Opis: V diplomskemu delu smo načrtali sistem vodenja termoelektričnega hladilnika. Termoelektrični hladilniki so naprave, ki uporabljajo Peltierjev pojav za hlajenje manjših naprav in zagotavljajo njihovo učinkovito delovanje. V načrtanem sistemu smo uporabili termoelektrični hladilnik manjših dimenzij in omejitvijo napajelne napetosti 3V oz. omejitvijo maksimalnega napajalnega toka 3A. Za učinkovito hlajenje se zahteva konstanten napjalni tok. Iz tega razloga smo uporabili namensko integrirano vezje ADN8831 in digitalno vodenje s pomočjo MAX5715 kot DAC pretvornik. Opravljen je bil preizkus vodenja izbranega termoelektričnega hladilnika, ki je pokazal dobro regulacijo temperature.
Ključne besede: termoelektrični hladilnik, Matlab, regulacija temperature, Peltierjev pojav, regulacija
Objavljeno v DKUM: 06.02.2024; Ogledov: 141; Prenosov: 20
.pdf Celotno besedilo (2,27 MB)

3.
Urban greening as a cooling tool towards the heat island effect
Anja Bubik, Lucija Kolar, 2019, izvirni znanstveni članek

Opis: Roofs, as the top layer of the urban environment, significantly contribute to overheating and creating a heat island, which is known as one of the most critical global warming effects. There are several ways to mitigate the effects of such heat islands, among which greening is the most natural, sustainable solution, and also economically acceptable and socially valued principle. Vegetation is known to significantly improve the urban microclimate and directly reduce the effect of the urban thermal core. At the Environmental Protection College in collaboration with the Institute Complementarium, both based in Slovenia, we conducted a pilot experiment to evaluate greening, in our case the principle of a flat green roof, as an effective and promising approach for reducing an urban heat island and its effects. Temperature measurements have shown that the green surface can lower both the surface temperature itself (e.g., the roof) and the air surrounding the green surface. We have presented an initial pilot case, which is planned to be upgraded in the future to confirm our current results and assumptions. In addition, we summarized data showing that Velenje is, in view of annual higher average temperatures, a highly suitable urban environment for the introduction of greening principles on the top urban layers.
Ključne besede: air temperature, greening principle, heat island effect, pilot study, urban environment
Objavljeno v DKUM: 05.12.2023; Ogledov: 181; Prenosov: 4
.pdf Celotno besedilo (1,31 MB)
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4.
The Influence of Increased Moderator Temperature on the Nuclear Characteristics of the NPP Krško
Marjan Kromar, Bojan Kurinčič, 2019, objavljeni znanstveni prispevek na konferenci

Opis: NPP Krško safety analysis has been performed in such a way to allow operation with primary system average coolant temperature - Tavg inside a prescribed range, which constitute the socalled operating window. The Tavg window enables certain flexibility to select an optimum value within the Tavg range taking into account safety, operational and economical considerations. Increase of the reactor coolant temperature in general improves thermodynamic efficiency of the Pressurized Water Reactor (PWR) plant yielding to increase in the electricity production. However, higher temperature causes lower water density in the reactor core altering the neutron moderation and consequently neutron transport in the reactor. This impact on the nuclear core characteristics is investigated for the NPP Krško reactor core.
Ključne besede: pressurized water reactor, nuclear design calculations, reactor coolant temperature optimization, critical boron concentration, Nuclear Powe Plant Krško
Objavljeno v DKUM: 05.12.2023; Ogledov: 168; Prenosov: 7
.pdf Celotno besedilo (18,06 MB)
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5.
Static model of temperature distribution in a photovoltaic module
Klemen Sredenšek, Sebastijan Seme, Gorazd Hren, 2021, izvirni znanstveni članek

Opis: The primary objective of this paper is to present a static model for calculating the temperature distribution in a photovoltaic module using the finite element method. The paper presents in more detail the theoretical background of solar radiation, heat transfer, and the finite element method. The results of the static model are evaluated using temperature measurements of a photovoltaic model, which were performed at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor. The results of the regression analysis show a good concurrence between the measured and modelled values of the temperature of the photovoltaic module, especially on days with a higher share of the direct component of solar radiation.
Ključne besede: photovoltaic module, temperature distribution, heat transfer, finite element method
Objavljeno v DKUM: 13.11.2023; Ogledov: 125; Prenosov: 5
.pdf Celotno besedilo (2,01 MB)
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6.
Experimental validation of a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank
Klemen Sredenšek, Sebastijan Seme, Bojan Štumberger, Miralem Hadžiselimović, Amor Chowdhury, Zdravko Praunseis, 2021, izvirni znanstveni članek

Opis: The primary objective of this paper is to present a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank. The added value of the proposed model is the use and integration of existing dynamic models for describing the entire photovoltaic/thermal system. The presented model was validated using measurements on the experimental system located at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor. The validation was carried out based on three different weather conditions—sunny, cloudy, and overcast. The validation results were evaluated using the normalized root mean square error and mean absolute percentage error for the temperature and output power of the photovoltaic/thermal collector and the temperature of the thermal energy storage tank. The model results concurred with the measurements, as the average mean absolute percentage error values for the temperature and output power of the photovoltaic/thermal collector and thermal energy storage tank temperature were 5.82%, 1.51%, and 7.58% respectively.
Ključne besede: photovoltaic/thermal collector, thermal energy storage tank, dynamic modeling, temperature distribution, output power
Objavljeno v DKUM: 13.11.2023; Ogledov: 124; Prenosov: 9
.pdf Celotno besedilo (8,22 MB)
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7.
Experimental validation of a thermo-electric model of the photovoltaic module under outdoor conditions
Klemen Sredenšek, Bojan Štumberger, Miralem Hadžiselimović, Sebastijan Seme, Klemen Deželak, 2021, izvirni znanstveni članek

Opis: An operating temperature of the photovoltaic (PV) module greatly affects performance and its lifetime. Therefore, it is essential to evaluate operating temperature of the photovoltaic module in different weather conditions and how it affects its performance. The primary objective of this paper is to present a dynamic thermo-electric model for determining the temperature and output power of the photovoltaic module. The presented model is validated with field measurement at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor, Slovenia. The presented model was compared with other models in different weather conditions, such as clear, cloudy and overcast. The evaluation was performed for the operating temperature and output power of the photovoltaic module using Root-Mean-Square-Error (RMSE) and Mean-Absolute-Error (MAE). The average RMSE and MAE values are 1.75C and 1.14C for the thermal part and 20.34 W and 10.97 W for the electrical part.
Ključne besede: dynamic modeling, thermo-electric model, accuracy, measuring device, temperature, output power, PV module
Objavljeno v DKUM: 13.11.2023; Ogledov: 205; Prenosov: 11
.pdf Celotno besedilo (9,51 MB)
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8.
Validation of the T6 temperature class for an explosion - proof induction motor
Gregor Srpčič, Miralem Hadžiselimović, Iztok Brinovar, Klemen Sredenšek, Sebastijan Seme, Bojan Štumberger, 2022, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: induction motor, temperature class, over-load test, temperature rise test
Objavljeno v DKUM: 27.10.2023; Ogledov: 267; Prenosov: 3
.pdf Celotno besedilo (14,78 MB)
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9.
Thermal analysis of a coreless axial flux permanent magnet machine
Franjo Pranjić, Marko Pezdevšek, Peter Virtič, 2022, izvirni znanstveni članek

Opis: The article deals with numerical analysis of a double sided coreless axial flux permanent magnet machine with two rotor disks and a coreless stator. Coreless stator represents copper windings which are held together by epoxy raisin, therefore a special focus has to be given to the stator temperature. In this article a numerical analysis is presented, which is based on the copper losses, namely the I2R product, where the resistance of the copper windings was both calculated as well as measured in the prototype machine.
Ključne besede: axial flux, CFD, coreless, permanent magnet, temperature distribution
Objavljeno v DKUM: 27.10.2023; Ogledov: 155; Prenosov: 9
.pdf Celotno besedilo (1,23 MB)
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10.
Light-induced palladium-catalyzed Buchwald Hartwig amination : master's thesis
Andraž Oštir, 2023, magistrsko delo

Opis: The goal of this master’s thesis was to investigate the use of light to enable the acceleration of the Buchwald-Hartwig amination of deactivated aryl chlorides with an ammonium source using a newly developed and optimized state-of-the-art catalyst system. A photoreactor was designed, modelled, and constructed to allow for a reproducible reaction setup under controlled conditions. The optimal light source and reaction conditions were investigated using a model reaction. Conversion of the starting material, product yield and potential byproducts were quantified by gas chromatography (GC) analysis and confirmed by mass spectroscopy (GC/MS). The use of light (3 W 447 nm) enabled the accelerated conversion of aryl chlorides towards the amination products even at room temperature in 2 hours, which is a remarkable improvement upon the previously reported state-of-the-art. Under optimized conditions, the highest yield (88 %) was achieved using a catalyst complex formed from β-methyl naphthyl (β-MeNAP) palladium bromide and the sterically demanding ligand AdBrettPhos. The structure of the complex crystal was elucidated using X-ray crystallography after the crystallization of the catalyst species.
Ključne besede: Buchwald-Hartwig amination, photochemistry, palladium, room temperature, ammonium salt
Objavljeno v DKUM: 03.10.2023; Ogledov: 497; Prenosov: 48
.pdf Celotno besedilo (3,76 MB)

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