Iskanje po katalogu digitalne knjižnice

Opis: A digital twin of lyophilization units was developed to facilitate the scale-up of the lyophilization process from the laboratory to the commercial scale. Our focus was on ensuring successful technology transfer for manufacture of high-quality drug products. Traditionally, lyophilization models have been specific either to the equipment or to the vial. In this study, we integrated the equipment and the vial models in a way that they mutually influenced each other via boundary conditions (two-way coupling). We conducted two sets of calculations. Firstly, we performed steady-state simulations using Computational Fluid Dynamics (CFD) to simulate an ice slab test, which helped determine the equipment capability curve. Secondly, we carried out transient, coupled simulations using a coupled 3-D CFD and 1-D vial scale simulation model to mimic the primary drying phase in a lyophilizer. Using the coupled 3-D CFD and 1-D vial scale model, we were able to determine the product temperature, the sublimation rate and the cycle time based on the temporal and spatial conditions in the lyophilizer. The coupled approach was then applied to capture the effects of process disturbances and failure conditions in the lyophilizer, which enables a more robust process design.
Ključne besede: lyophilization, freeze-drying, sublimation
Objavljeno v DKUM: 13.03.2025; Ogledov: 0; Prenosov: 9
Celotno besedilo (9,42 MB)
Gradivo ima več datotek! Več...

Opis: V diplomskem delu je predstavljena analiza temperaturne porazdelitve po polici laboratorijskega kontaktnega liofilizatorja. Predstavljeno je teoretsko ozadje procesa liofilizacije. Z osmimi termočleni smo izmerili temperaturo po polici liofilizatorja pri dveh različnih postavitvah in pri treh različnih nastavljenih temperaturah police liofilizatorja. S pomočjo numeričnih simulacij smo v poenostavljenem in zanesljivem modelu sestava komore in polic liofilizatorja dobili rezultate temperature izmerjene na istoležnih točkah, kakor pri eksperimentu. Sledila je obdelava podatkov in primerjava v ujemanju dobljenih rezultatov. V diplomskem delu smo ugotovili, da v določenih primerih prihaja do neuniformnosti porazdelitve temperature po polici liofilizatorja, kar lahko pomembno vpliva na učinkovitost procesa liofilizacije.
Ključne besede: termočleni, računalniška dinamika tekočin, liofilizacija, prenos toplote
Objavljeno v DKUM: 06.03.2025; Ogledov: 0; Prenosov: 20
Celotno besedilo (4,00 MB)

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: 22
Celotno besedilo (3,29 MB)
Gradivo ima več datotek! Več...

Opis: V doktorski disertaciji so predstavljeni rezultati raziskav na temo eksperimentalnega dela določanja kinetike sušenja med procesom liofilizacije in ovrednotenja procesne zmogljivosti naprave, ter razviti numerični modeli za celovito modeliranje procesa in rezultati le teh. V sklopu eksperimentalnega dela se je ovrednotila kinetika sušenja destilirane vode (sublimacija ledu), ter eksperimentalna določitev kinetike depozicije ledu, kjer se je za tok vodne pare, ki je v režimu dušenega toka, izmerilo masne tokove sublimata in tlake znotraj sušilne komore in kondenzatorja.\\ Rezultati eksperimentov so nato služili za validacijo razvitih numeričnih modelov. Simulacije, ki vključujejo RDT preračune so bile pripravljene v računalniškem programu ANSYS Fluent ali v programskem jeziku Fortran. Razvilo se je več modelov različnih kompleksnosti, prvi model je model za ovrednotenje vpliva geometrije gumastega zamaška in vrata viale na tlačni padec in vpliv na proces, kjer se je tok sublimata modeliral v RDT programu, medtem ko se je kinetika sušenja računala s pomočjo 0D modela (sklopljen 0D-RDT model). Na podlagi rezultatov, se je določilo empirično korelacijo za opis le tega pojava. Naslednji model je večnivojsko sklopljen model z uporabo TCP strežnika, ki povezuje 1D program za simuliranje kinetike sušenja znotraj viale (napisan v programskem jeziku Fortran) s komercialno kodo ANSYS Fluent, ki je uporabljen za izračun tokovnih polj skozi sistem. Kinetika sušenja produkta v vsaki viali je simulirana z 1D modelom, v katerem se tlačni padec vodne pare, med tokom skozi zgornji prostor viale, obravnava z empirično korelacijo. Masni tokovi sublimata in temperatura plina se posredujejo RDT modelu, ki jih uporabi kot robne pogoje na lokalnih vtokih. Po izračunu novega tokovnega polja, RDT model vrne nove tlake nad vsako vialo. Na ta način dobimo vpogled v hidrodinamske razmere znotraj liofilizatorja in kinetiko sušenja vseh vial. Naslednji del je modeliranje depozicije ledu, kjer se je modeliral tok sublimata skozi celoten sistem, depozicija na hladnih stenah kondenzatorja pa se modelira z dodatnimi členi za ponor mase, gibalne količine in energije. V tem primeru se torej meja modeliranja prestavi v kondenzator, kar nam omogoči vpogled v dogajanje znotraj kondenzatorja in vzorec depozicije ledu, ki se odvija v kondenzatorju.
Ključne besede: RDT, liofilizacija, večnivojski model, prenos toplote in snovi, depozicija
Objavljeno v DKUM: 27.10.2023; Ogledov: 508; Prenosov: 149
Celotno besedilo (35,49 MB)

Opis: The flow conditions during the experiment LIVE2D on reactor core melt behaviour in the lower plenum of a reactor pressure vessel, performed at the Karlsruhe Institute of Technology (Germany), were simulated with a Computational Fluid Dynamics computer code. In this hypothetical severe accident scenario in a pressurized water reactor nuclear power plant, the melt is divided into an oxidic layer and a metallic layer on top of it, and the oxidic layer is volumetrically heated due to decay heat. In the experiment, oil and salt were used as simulant materials for metallic and oxidic melt, respectively. The main goal of performed simulations was to investigate the so-called “focusing effect”, where a thin layer of the reactor vessel steel wall is exposed to high heat flux. Due to the length of experiment, which exceeds 100 hours, only intervals of the melt behaviour were simulated. Four cases were simulated. The first case investigated different boundary conditions for the oil layer behaviour for layer thickness 35 mm. The second case investigated the same conditions with added modelling of the reactor vessel steel wall and salt crust from the lower layer. The third case used similar modelling as the second case to investigate the oil layer behaviour for layer thickness 75 mm. The fourth case investigated both salt and oil layers for oil layer thickness 75 mm. Different analytical and numerical calculations were performed to determine heat losses from simulant liquids to the surroundings, which played an important part in the experiment.
Ključne besede: nuclear power plant, severe accident, reactor core melt, lower plenum, heat flux focusing effect
Objavljeno v DKUM: 17.09.2019; Ogledov: 1417; Prenosov: 211
Celotno besedilo (6,83 MB)