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1.
Sklopljeni numerični model prenosa gibalne količine, energije in snovi med procesom depozicije ledu v kondenzatorju liofilizatorja
Klemen Meh, 2025, magistrsko delo

Opis: Magistrska naloga obravnava numerično modeliranje prenosa gibalne količine, energije in snovi med procesom depozicije ledu v kondenzatorju liofilizatorja. Osredotočili smo se na modeliranje robnega pogoja temperature na hladni steni kondenzatorja. Dosedanji numerični modeli so temeljili na konstantnem robnem pogoju temperaturnega profila na hladni steni kondenzatorja. V tem magistrskem delu pa smo izpeljali enačbe za izračun temperaturnega profila na hladni steni kondenzatorja in jih preizkusili na poenostavljenem modelu. Numerično smo simulirali stacionarne razmere s predpisanim robnim pogojem temperature na realnem modelu. Nato smo simulirali proces depozicije ledu v trajanju ene ure s pomočjo uporabniško definiranih funkcij pri dveh obratovalnih režimih. Ugotovili smo, da je učinkovitost kondenzatorja nekoliko nižja v primerjavi z dosedanjimi rezultati drugih raziskovalcev, dobljenih z upoštevanjem konstantnega robnega pogoja temperaturnega profila na hladni steni kondenzatorja. Razlika rezultatov med dvema različnima pristopoma pa ni izrazita. Naši rezultati so tudi skladni z ugotovitvami drugih avtorjev, ki so prav tako opazili, da je temperatura najvišja na mestu, kjer se začne hladilna tuljava, prav tako pa sta tam najintenzivnejša ponor vodne pare in depozicija ledu.
Ključne besede: prenosni pojavi, numerične simulacije, liofilizacija, kondenzator vodne pare, ANSYS Fluent, uporabniško definirane funkcije.
Objavljeno v DKUM: 05.02.2025; Ogledov: 0; Prenosov: 9
.pdf Celotno besedilo (7,82 MB)

2.
Razvoj sistema za nadzor vlažnosti v mikrookolici nanopreciznega robota s Peltierjevim elementom
Smiljana Milošević, 2024, diplomsko delo

Opis: V diplomskem delu raziskujemo razvoj sistema za nadzor vlažnosti v mikrookolici nanopreciznega robota s Peltierjevim elementom. Cilj je bil ugotoviti, ali lahko Peltierjev element učinkovito regulira relativno vlažnost v komori za manipulacijo mikro objektov v nanorobotiki. Sistem uporablja senzorje za merjenje temperature in vlažnosti ter mikrokrmilnika Arduino in STM32 za vodenje sistema. Za upravljanje in prikaz rezultatov je bil razvit grafični vmesnik v programskem jeziku Python. Delo vključuje tudi modeliranje procesa in implementacijo PID regulatorja za optimizacijo nadzora vlažnosti.
Ključne besede: nanorobotika, Peltierjev element, Python, STM32, Ansys
Objavljeno v DKUM: 22.10.2024; Ogledov: 0; Prenosov: 13
.pdf Celotno besedilo (24,76 MB)

3.
Superkritična CO2 ekstrakcija eteričnih olj : diplomsko delo
Tadej Oprčkal, 2024, diplomsko delo

Opis: V nalogi je obravnavan proces superkritične CO2 ekstrakcije, ki predstavlja mnogo prednosti v primerjavi s konvencionalnimi metodami. V delu so zbrani uporabljeni obratovalni parametri procesa za pridobivanje raznih ekstraktov iz prakse, na podlagi česar so bili izbrani obratovalni pogoji za analitični izračun elementov postrojenja, ki bo lahko služil za nadaljnjo možnost konstruiranja in sicer: maksimalni obratovalni tlak ekstrakcijske posode 350 bar, maksimalno temperaturo 60 °C, volumnom ekstrakcijske posode 5l in volumskim pretokom 50l/h. Izračunane potrebne moči elementov postrojenja pa so: moč kondenzatorja 2814 W, moč visokotlačne črpalke 384 W, ki omogoča dvig tlaka na 350 bar, moč grelca 793 W ter moč grelca v separatorju 2093 W. Možnosti nadaljnjih študij je veliko, predvsem z iskanjem optimalnih parametrov procesa, preko eksperimentov, za pridobivanje točno določenih ekstraktov.
Ključne besede: ogljikov dioksid, ekstrakcija, superkritično stanje, eterično olje
Objavljeno v DKUM: 09.10.2024; Ogledov: 0; Prenosov: 24
.pdf Celotno besedilo (2,96 MB)

4.
A coupled point particle two-phase heat and mass transfer model for dispersed flows based on Boundary Element Methods
Timi Gomboc, Matej Zadravec, Jure Ravnik, Matjaž Hriberšek, 2024, objavljeni znanstveni prispevek na konferenci

Opis: In dispersed multiphase flow processes we encounter coupled heat, mass and momentum transfer between the disoersed and the continuous phase. In the context of the subdomain Boundary Domain Integral Method (BDIM) solution of the Navier-Stokes equations a two-way coupling model is presented based on the use of the elliptic fundamental solution and the Dirac delta function properties which leads to accurate evaluation of the heat and mass point particle source impacts on the continuous (air) phase. In addition, the two-phase flow case under consideration is extended to the case of porous spherical particle drying with internal moving drying front, which is solved by the Boundary Element Method (BEM).
Ključne besede: heat transfer, mass transfer, Boundary Element Methods
Objavljeno v DKUM: 01.07.2024; Ogledov: 113; Prenosov: 15
.pdf Celotno besedilo (1,10 MB)
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5.
Modeliranje in izdelava dušilca zvoka za strelno orožje
Luka Šatan, 2024, magistrsko delo

Opis: Cilj magistrske naloge je bil izdelati dušilec zvoka za strelno orožje modela M70 s kalibrom 7,62 × 39 mm. Prvotno je bilo treba analizirati in proučiti, do sedaj že znane študije in pregledati že izdelane dušilce. Na podlagi teh smo v programskem okolju SolidWorks oblikovali štiri različne oblike ekspanzijskih komor, na katerih smo na to v istem programskem okolju izvedli analizo zračnega tlaka in akustičnih moči. Po končani analizi smo komore in ostale potrebne sklope dušilca izvozili v obliki STEP formata in dušilec fizično izdelali na CNC obdelovalnem stroju. Za izdelane dušilce smo izvedli tudi meritve jakosti zvoka na terenu. Na koncu smo določili najprimernejši dušilec za obravnavano strelno orožje.
Ključne besede: strelno orožje, dušilec zvoka, hrup, modeliranje, izdelava, SolidWorks
Objavljeno v DKUM: 30.05.2024; Ogledov: 168; Prenosov: 34
.pdf Celotno besedilo (4,22 MB)

6.
Numerična analiza tokovnih razmer v kondenzacijskem delu prenosnika toplote : magistrsko delo
Dejan Sevčnikar, 2024, magistrsko delo

Opis: V zmogljivih baterijskih električnih vozilih se kompaktni ploščni prenosniki toplote uporabljajo za zagotavljanje odvoda toplote iz kompresorskega parnega hladilnega kroga. V magistrskem delu smo obravnavali kondenzacijo hladiva v takšnem prenosniku toplote. Pripravili smo geometrijo prenosnika toplote in jo zamrežili s strukturirano mrežo. Izvedli smo analizo vpliva debeline elementa pri steni in analizo kalibracijskega parametra kondenzacijskega modela. Na podlagi rezultatov smo izbrali primerne kalibracijske vrednosti in izvedli variacijo masnega pretoka. Rezultate variacije masnega pretoka smo primerjali z meritvami iz referenčnega članka in ugotovili, da lahko, z uporabo navedenega modela, razmeroma natančno napovemo prestop toplote in suhost pare za izbrani primer. Prav tako smo s simulacijo potrdili trende, ki se pojavljajo pri spremembah masnega pretoka in suhosti pare.
Ključne besede: kondenzacija, numerična analiza, prenosnik toplote, hladivo
Objavljeno v DKUM: 22.04.2024; Ogledov: 210; Prenosov: 0
.pdf Celotno besedilo (6,20 MB)

7.
Study of ▫$Ni/Y_2O_3/polylactic$▫ acid composite
Tilen Švarc, Matej Zadravec, Žiga Jelen, Peter Majerič, Blaž Kamenik, Rebeka Rudolf, 2023, izvirni znanstveni članek

Opis: This study demonstrates the successful synthesis of Ni/Y2O3 nanocomposite particles through the application of ultrasound-assisted precipitation using the ultrasonic spray pyrolysis technique. They were collected in a water suspension with polyvinylpyrrolidone (PVP) as the stabiliser. The presence of the Y2O3 core and Ni shell was confirmed with transmission electron microscopy (TEM) and with electron diffraction. The TEM observations revealed the formation of round particles with an average diameter of 466 nm, while the lattice parameter on the Ni particle’s surface was measured to be 0.343 nm. The Ni/Y2O3 nanocomposite particle suspensions were lyophilized, to obtain a dried material that was suitable for embedding into a polylactic acid (PLA) matrix. The resulting PLA/Ni/Y2O3 composite material was extruded, and the injection was moulded successfully. Flexural testing of PLA/Ni/Y2O3 showed a slight average decrease (8.55%) in flexural strength and a small decrease from 3.7 to 3.3% strain at the break, when compared to the base PLA. These findings demonstrate the potential for utilising Ni/Y2O3 nanocomposite particles in injection moulding applications and warrant further exploration of their properties and new applications in various fields.
Ključne besede: ultrasound spray pyrolysis, Ni/Y2O3, lyophilization, PLA, extrusion, injection moulding
Objavljeno v DKUM: 05.04.2024; Ogledov: 199; Prenosov: 20
.pdf Celotno besedilo (3,29 MB)
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8.
Design of an Efficient Fan Steering Strategy for Efficient Cooling of Engine Peripheral Components during Vehicle Thermal Soak : magistrsko delo
Tjaša Pečnik, 2024, magistrsko delo

Opis: The aim of this Master's thesis was to find a mathematical correlation between various fan momentum fields for a fan which is used for cooling the underhood area of a car. The correlation had to link a known momentum field to all possible momentum fields related to fan rotation speed and car velocity. With this correlation, new alternative fan steering strategies can be used to cool the vehicle underhood area. An already functioning RBM (Rigid Body Motion) simulation was used as a base, since it already gave satisfying results in the past. With this simulation file, several tests were run to ensure that the results really converge nicely. In this way it was established that the results are accurate enough for further use. After obtaining the results, a set of 30 simulation files was calculated. The simulations were a combination of different fan rotation speeds and car velocities. After the set was done, the results were analysed using various computer software (Star-CCM+, MS Excel and Matlab). It was concluded that a polynomial approach for the momentum field was a suitable option but to add some additional complexity, surface equations were used. To obtain the equations, tables with different results were put into Matlab and the program did the rest. The result were two sets of three surface equations with x and y values. In both cases, x represented the rotation speed of the fan and y represented the car velocity in one case and the delta pressure between two evaluation surfaces in the other. After that it was time to implement the newly acquired surface equations in a Star-CCM+ simulation file. The old simulation file was again used as a base, but new field functions were put in with the help of which the UDMS (User Defined Momentum Source) is being changed. Both types of surface equations were tested and calculated. In the end, it was decided to go with the one where the delta pressure on two evaluation surfaces is being used as the y value. One surface was placed in front of the fan and the other after the fan. The final step was to test different fan steering strategies. The usual cooling procedure consists of a phase where the fan cools for a specific amount of time with a defined rotation speed and then turns off. Temperatures on critical points around the engine and in the underhood area of the car are being looked at as a result. The first strategy was to run the fan at the same speed as usual, but gradually slow it down in uniform steps so that the shut down time remains the same. With this approach, the highest temperature values were actually lower than usual, but certain temperature probes became warmer as the fan speed decreased. Nevertheless, the temperatures at the end were very similar. The second tested strategy was inspired by the idea of potentially saving some battery energy if we could somehow manage to cool the underhood area quicker. In this case, the fan ran for a short time at a high rotation speed and after that at a slightly lower speed. Then it was turned off for a few minutes and subsequently switched back on. The maximum temperature in this scenario reached even higher values. The reason for this was that the fan blew warm air toward certain measurement points, causing them to heat up further. The temperatures at the end of the simulation were similar to those in the previous two cases. In conclusion, it is indeed possible to steer a fan momentum field with the help of field functions and equations which describe the relationship between different fan rotation speeds and car velocities.
Ključne besede: fan, momentum, RBM, CFD, thermal soak
Objavljeno v DKUM: 02.04.2024; Ogledov: 225; Prenosov: 0
.pdf Celotno besedilo (13,61 MB)

9.
Numerično modeliranje dvofaznega toka v mali čistilni napravi : diplomsko delo
Žan Frumen, 2022, diplomsko delo

Opis: V diplomskem delu je s pomočjo računalniške dinamike tekočin, opravljena numerična analiza dvofaznega toka v mali čistilni napravi. Predstavljene so geometrijske lastnosti ter vplivni parametri, kot tudi aeracija v mali čistilni napravi. V nadaljevanju je predstavljeno teoretično ozadje modeliranja. Izpeljana sta tudi ohranitvena zakona mase in gibalne količine. Izvedena je bila poliedrična mreža, analiza vplivnih parametrov pretoka in velikosti mehurčka zraka na aeracijo. Na koncu je bil računan indeks uniformnosti porazdelitve volumskega deleža zraka v mali čistilni napravi. Ugotovljene in predstavljene so optimalne razmere za opravljeno simulacijo.
Ključne besede: mala čistilna naprava, računalniška dinamika tekočin, ANSYS Fluent, aeracija, simulacija
Objavljeno v DKUM: 05.03.2024; Ogledov: 308; Prenosov: 29
.pdf Celotno besedilo (2,36 MB)

10.
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