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1.
Underground coal gasification - the Velenje coal mine energy and economic calculations
Damjan Konovšek, Zdravko Praunseis, Jurij Avsec, Gorazd Berčič, Andrej Pohar, Simon Zavšek, Milan Medved, 2017, original scientific article

Abstract: Underground coal gasification (UCG) is a viable possibility for the exploitation of vast coal deposits that are unreachable by conventional mining and can meet the energy, economic and environmental demands of the 21st century. Due to the complexity of the process, and the site-specific coal and seam properties, it is important to acknowledge all the available data and past experiences, in order to conduct a successful UCG operation. Slovenia has huge unmined reserves of coal, and therefore offers the possibility of an alternative use of this domestic primary energy source. According to the available underground coal gasification technology, the energy and economic assessment for the exploitation of coal to generate electricity and heat was made. A new procedure for the estimation of the energy efficiency of the coal gasification process, which is also used to compare the energy analyses for different examples of coal exploitation, was proposed, as well as the technological schemes and plant operating mode in Velenje, and the use of produced synthetic coal gas (syngas). The proposed location for the pilot demonstration experiment in Velenje Coal Mine was reviewed and the viability of the underground coal gasification project in Velenje was determined.
Keywords: underground coal gasification, syngas, clean coal technology, energy analysis, economic analysis
Published: 31.08.2017; Views: 71; Downloads: 6
.pdf Full text (1,32 MB)

2.
Izkoriščanje sončne energije za ogrevanje in hlajenje inštituta za energetiko
Uroš Krošelj, 2017, undergraduate thesis

Abstract: V diplomskem delu sem raziskoval možnosti uporabe sončne energije za ogrevanje in hlajenje inštituta za energetiko. Namen raziskovanja je ugotoviti, kakšne so možnosti uporabe paraboličnih sončnih kolektorjev za točno določen prostor. Osredotočil sem se na prostor, ki zajema Laboratorij za termomehaniko, termoenergetiko in nanotehnologije (LTTN), Laboratorij za energetske pretvorbe (LEP) in Laboratorij za energetski management in inženiring (LABEMI). Najprej sem izračunal toplotne izgube laboratorija, da sem dobil informacijo, koliko toplotne energije potrebujemo za oskrbo tega prostora. Nato pa sem projektiral sistem ogrevanja oziroma ohlajevanja prostora z vsemi potrebnimi elementi.
Keywords: parabolični kolektorji, sončna energija, sončna kogeneracija
Published: 21.08.2017; Views: 188; Downloads: 1
.pdf Full text (2,69 MB)

3.
Načrtovanje lahkega plovila na vodikovo gorivo
Filip Mlinarić, 2017, master's thesis

Abstract: V magistrskem delu je podana rešitev konstrukcije lahke večsedežne ladje s pogonom na vodikovo gorivo. Poleg konstrukcijske rešitve je v delu podana tudi polnilna naprava za vodik z uporabo sončne in vetrne elektrarne. Ekonomska analiza podaja izračun stroškov plovila za vodikovo gorivo.
Keywords: Lahko aluminijasto plovilo, vodik, polnilna postaja
Published: 21.08.2017; Views: 162; Downloads: 43
.pdf Full text (5,52 MB)

4.
Preračun geometrije lopatice vetrne turbine in prenos v cad sistem
Igor Ščuri, 2017, master's thesis

Abstract: Za magistersko nalogo smo izvedli proceduro za izračun geometrije lopatice vetrne turbine v Excelu. Izračun geometrije lopatice temelji na metodi »Blade element theory«, ki je del BEM metode. Razika med našo proceduro in omenejima metodama je le v tem, da je v omenjenih metodah geometrija lopatice vetrne turbine že dana. Preračunano geometrijo s pomočjo izvedenega programa prenesemo v program SolidWorks tako, da program najprej izriše krivulje profilov in jih podem s funkcijo »Loft« poveže v lopatico. Program izračuna optimalno geometrijo lopatice z upoštevanjem rotirajoče brazde, ki je modelirana v SolidWorksu. Geometrijo lopatice preračunamo le s kliki na gumbe v programu, prav tako jo s kliki na gumbe tudi modeliramo v SolidWorksu. V nalogi je natančneje predstavljeno delovanje programa.
Keywords: preračun, geometrija lopatice vetrne turbine, modeliranje
Published: 18.08.2017; Views: 161; Downloads: 15
.pdf Full text (2,90 MB)

5.
Zagotavljanje kakovosti jeklenih zvarnih spojev
Sandi Ajster, 2017, master's thesis

Abstract: Varjenje je zelo pomemben način spajanja materialov v nerazstavljivo zvezo in je prisotno v mnogih panogah proizvodnje in vzdrževanja z najrazličnejšimi materiali. Zvar je pa del zvarjene celote in mora imeti poseben poudarek pri zagotovitvi sprejemljive kakovosti za katero je namenjen. Jeklo in jekleni zvarni spoji so zelo pomemben in razširjen člen pri gradnji jeklenih konstrukcij in energetskih komponent. Magistrski delo zajema prikaz vodenja kakovosti in standarde iz področja zagotavljanja kakovosti varilskih del, ki so sestavni del certifikata ISO9001 za varilsko področje. Praktični del naloge pa zajema izvedbo varilnih prob in porušnih preiskav dveh varilnih postopkov pred samo izvedbo certificiranja varilskega postopka in varilcev.
Keywords: Varjenje, zvarni spoji, kakovost, jeklo, porušne preiskave, trdota
Published: 18.08.2017; Views: 74; Downloads: 9
.pdf Full text (2,22 MB)

6.
Uvedba učinkovite razsvetljave v industriji
Damjan Mežič, 2017, master's thesis

Abstract: Vsak industrijski objekt je znan po tem, da ima veliko porabo električne energije predvsem zaradi tehnologije dela. Redko pomislimo, da se lahko z uvedbo učinkovite razsvetljave dodatno prihrani pri porabi električne energije in hkrati zagotovi ugodje in boljše počutje zaposlenih. V magistrski nalogi sem povzel na kratko splošna dejstva o razsvetljavi in svetlobnotehničnih veličinah. Namreč, s projektiranjem razsvetljave v industriji se ne srečujemo ravno vsak dan, zato so podana priporočila in primeri dobre prakse pri načrtovanju tovrstne razsvetljave. Opisani so sistemi, kako lahko dokaj enostavno projektiramo učinkovito razsvetljavo, na drugi strani pa smo omejeni z zakonodajo, in standardi. Naloga je zaključena s primerom obstoječe razsvetljave v industriji izvedeni s fluorescentnimi sijalkami brez regulacije ter predlogom za vgradnjo učinkovite LED razsvetljave s pametno regulacijo.
Keywords: učinkovita razsvetljava, LED razsvetljava, industrija, optimizacija razsvetljave, krmiljenje razsvetljave
Published: 18.08.2017; Views: 46; Downloads: 9
.pdf Full text (1,01 MB)

7.
Limit cycle bifurcated from a center in a three dimensional system
Bo Sang, Brigita Ferčec, Qin-Long Wang, 2016, original scientific article

Abstract: Based on the pseudo-division algorithm, we introduce a method for computing focal values of a class of 3-dimensional autonomous systems. Using the $Є^1$-order focal values computation, we determine the number of limit cycles bifurcating from each component of the center variety (obtained by Mahdi et al). It is shown that at most four limit cycles can be bifurcated from the center with identical quadratic perturbations and that the bound is sharp.
Keywords: algorithms, three dimensional systems, focal value, limit cycle, Hopf bifurcation, center
Published: 08.08.2017; Views: 76; Downloads: 1
.pdf Full text (236,33 KB)

8.
Exergy analysis of a Brayton cycle with variable physical properties and variable composition of working substance
Marija Živić, Antun Galović, Jurij Avsec, Mario Holik, 2016, original scientific article

Abstract: The exergy analysis of a Brayton cycle is performed in the paper. The four input variables: the ratio of the compressor exit and inlet pressures, the ratio of inlet temperature of gases in turbine and inlet temperature of air in compressor and the isentropic efficiencies of the compressor and turbine are analysed. The temperature ratio is varied in a way that the compressor inlet temperature of air is maintained constant, while the turbine inlet temperature of flue gases is varied from 900 to 1200°C. In the combustion chamber methane is completely combusted with excess air ratio which is determined by the temperature of flue gases at the turbine inlet. The analysis further includes variability of the molar heat capacities of air and flue gases with temperature and variability of their heat capacity ratios. The exergy destruction in turbine, compressor and combustion chamber and also total exergy efficiency of the cycle are considered in the analysis.
Keywords: Brayton cycle, variable physical properties, variable composition of working substance, maximum work output, maximum thermal efficiency
Published: 12.07.2017; Views: 167; Downloads: 4
.pdf Full text (789,62 KB)

9.
The calculation of specific heats for some important solid components in hydrogen production process based on CuCl cycle
Jurij Avsec, 2014, original scientific article

Abstract: Hydrogen is one of the most promising energy sources of the future enabling direct production of power and heat in fuel cells, hydrogen engines or furnaces with hydrogen burners. One of the last remainder problems in hydrogen technology is how to produce a sufficient amount of cheap hydrogen. One of the best options is large scale thermochemical production of hydrogen in combination with nuclear power plant. copper-chlorine (CuCl) cycle is the most promissible thermochemical cycle to produce cheap hydrogen.This paper focuses on a CuCl cycle, and the describes the models how to calculate thermodynamic properties. Unfortunately, for many components in CuCl cycle the thermochemical functions of state have never been measured. This is the reason that we have tried to calculate some very important thermophysical properties. This paper discusses the mathematical model for computing the thermodynamic properties for pure substances and their mixtures such as CuCl, HCl, Cu2OCl2 important in CuCl hydrogen production in their fluid and solid phase with an aid of statistical thermodynamics. For the solid phase, we have developed the mathematical model for the calculation of thermodynamic properties for polyatomic crystals. In this way, we have used Debye functions and Einstein function for acoustical modes and optical modes of vibrations to take into account vibration of atoms. The influence of intermolecular energy we have solved on the basis of Murnaghan equation of state and statistical thermodynamics.
Keywords: thermodynamics, molecular crystals, mathematical models, statistical thermodynamics
Published: 07.07.2017; Views: 195; Downloads: 8
.pdf Full text (266,80 KB)

10.
Prenova ogrevalnega sistema v industrijskem podjetju
Gregor Rošer, 2017, undergraduate thesis

Abstract: Diplomska naloga je zasnovana na prenovi ogrevalnega sistema v industrijskem podjetju. Predstavljeno bo stanje pred obnovo in način delovanja stare kotlovnice. Naloga bo zajemala podatke porabljene energije in obratovalne stroške. Opisan bo projekt vgradnje plinskih kotlov in industrijskih plinskih grelnikov hkrati pa bo predstavljeno tudi plinovodno omrežje. Predstavljena bo stroškovna primerjava sistemov. Nazadnje pa bomo opisali učinkovitost delovanja novega sistema.
Keywords: ogrevalni sistem, kotli, plinovod, ogrevanje, prenova
Published: 14.06.2017; Views: 292; Downloads: 31
.pdf Full text (2,44 MB)

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