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1.
Formuliranje naproksena v polimere s superkritičnimi fluidi
Klemen Doplihar, 2020, undergraduate thesis

Abstract: Topnost farmacevtskih učinkovin je ena izmed najbolj pomembnih lastnosti. Ravno pravšnja topnost zdravila pomeni razliko med učinkovitim in neučinkovitim zdravilom. Nova zdravila imajo slabo topnost v vodi, zato vedno več farmacevtskih združb uporablja superkritične fluide za izboljšanje topnosti. Na topnost substance vplivajo tlak, temperatura, dodatek substanc, velikost delcev itd. Pri tem pa moramo paziti, da z eksperimenti ne poškodujemo strukture zdravila, saj lahko to povzroči spremembo v topnosti, biorazpoložljivosti in toksičnosti. Postopki, kot so določanje topnosti s superkritičnimi fluidi, RESS, PGSS in SAS, so se zelo razvili, kar je korak v pravo smer za sintezo zdravil. Diplomska naloga prikazuje določanje topnosti naproksena s superkritičnim CO2 pri različnih tlakih in temperaturah ter dodatkom različnih koncentracij so-topil. Za proces mikronizacije sta bila uporabljena procesa RESS in SAS, s katerima smo spremenili velikost in obliko delcev. Ugotovili so, da se topnost izboljša z višanjem temperature in z višanjem gostote raztopine oz. z višanjem tlaka. Dokazano je bilo, da je dodatek so-topila v splošnem povečal topnost naproksena, kjer je najboljši učinek imel 2-propanol. Največji učinek je imelo so-topilo pri najnižji koncentraciji le-tega. Procesa mikronizacije sta bila uspešna, saj so se delci zmanjšali v mikro in nano območje. Posnetki slik s SEM so pokazali, da so bili delci manjši pri procesu SAS, vendar je XRD graf pokazal, da so se delci naproksena strukturno spremenili, kar pa ima vpliv na topnost in biorazpoložljivost naproksena.
Keywords: naproksen, topnost, superkritični fluid, CO2
Published: 08.10.2020; Views: 63; Downloads: 14
.pdf Full text (2,01 MB)

2.
International Conference Fluid Power 2019
2019

Abstract: The International Fluid Power Conference is a two day event, intended for all those professionally-involved with hydraulic or pneumatic power devices and for all those, wishing to be informed about the ‘state of the art’, new discoveries and innovations within the field of hydraulics and pneumatics. The gathering of experts at this conference in Maribor has been a tradition since 1995, and is organised by the Faculty of Mechanical Engineering at the University of Maribor, in Slovenia. Fluid Power conferences are organised every second year and cover those principal technical events within the field of fluid power technologies in Slovenia, and throughout this region of Europe. This year's conference is taking place on the 19th and 20th September in Maribor.
Keywords: fluid power technology, components and systems, control systems, fluids, maintenance and condition monitoring
Published: 24.02.2020; Views: 233; Downloads: 20
URL Link to file

3.
Numerical analysis of fluid flow in a vial
Žiga Časar, 2019, master's thesis

Abstract: Lyophilization or freeze-drying is a widely used process in the pharmaceutical and food industry. In the process the solvent will be removed under extreme conditions of low temperature and low system pressures, whereby sublimation happens, the transition from the solid phase to the gas phase, with skipping the liquid phase, which happens bellow the triple point. This study focuses on numerical modeling at the start of the process, the so called primary drying. For this stage the highest mass flow rates of vapor are typical, since the driving force of the process is the pressure difference between the sublimation front and surrounding area. In this stage the non-bonded solvent is removed. Because of the extreme conditions the typical computational fluid dynamics approach is not suitable anymore and has to be corrected. One way to do this is to use additional models for fluid behavior at the solid wall. The study focuses on the influence of different boundary conditions on the solid wall, No-Slip, Free Slip and Maxwell Slip, and their effect on fluid flow inside the vial. A quantitative and qualitative comparison of the results is presented.
Keywords: Lyophilization, Knudsen number, computational fluid dynamics, fluid flow, numerical modeling, slip boundary condition
Published: 09.07.2019; Views: 519; Downloads: 103
.pdf Full text (2,66 MB)

4.
Toplotne lastnosti fluidov pri visokih tlakih
Gašper Zajc, 2017, master's thesis

Abstract: Namen magistrske naloge je bil preučevanje in ovrednotenje toplotnih lastnosti alternativnih nosilcev toplotne energije pri visokih tlakih, kjer smo se podrobneje posvetili ogljikovemu dioksidu in etanu ter njuni azeotropni mešanici. Ti fluidi lahko predstavljajo okolju prijaznejšo alternativo kakor trenutno najbolj razširjeni fluorirani ogljikovodiki. V magistrskem delu smo poleg eksperimentalnega dela v laboratoriju izvajali še razne simulacije v računalniškem programu Aspen Plus V8.8. V eksperimentalnem delu smo postavili delujoč kontinuirni dvocevni toplotni prenosnik, kjer smo merili koeficiente toplotne prestopnosti CO2, etana in njune azeotropne zmesi v odvisnosti od tlaka (od 5 MPa do 30 MPa), temperature (od 20 °C do 65 °C) in pretoka vode (pri 1 L/min in 2 L/min), ki je predstavljala hladen tok v našem protitočnem prenosniku. V drugem delu smo teoretično simulirali obratovanje subkritičnih toplotnih črpalk s CO2 in azeotropno zmesjo CO2 – etan. Opravili smo tudi simulacijo, kjer smo iskali optimalno sestavo azeotropne zmesi, ki bi dajala najvišje izkoristke procesa. Idejna zasnova teh simulacij je nastala zaradi različnih pogojev vrelišča azeotropnih zmesi v razmerju s čistimi snovmi, kar bi lahko potencialno znižalo obratovalne stroške toplotnih črpalk. Glavne ugotovitve so bile: Vsi merjeni visokotlačni fluidi so kazali maksimume toplotne prestopnosti tik nad kritičnimi pogoji. Ti vrhovi so se nato z višanjem tlaka nižali in premikali proti vedno višjim temperaturam. Tvorba teh vrhov je bila posledica specifične toplote fluida, ki je kazala enaka odstopanja nad kritično točko. Ugotovili smo tudi, da azeotropne zmesi tvorijo koeficiente toplotnih prestopnosti med obema komponentama, ki jo sestavljata. Simulativni rezultati analiz obratovanja toplotnih črpalk so kazali potencialne izboljšave izkoristkov procesa z vpeljavo azeotropne zmesi, vendar samo v določenih primerih. Na podlagi znižanja temperature vrelišča azeotropa CO2 – etan smo lahko obratovanje procesa izboljšali na kondenzatorju, vendar smo ga zaradi tega istočasno poslabšali na uparjalniku.
Keywords: CO2, etan, azeotrop, toplotni prenosnik, toplotna črpalka, superkritični fluid
Published: 22.11.2017; Views: 605; Downloads: 92
.pdf Full text (3,62 MB)

5.
International conference Fluid power 2017
2017, proceedings of peer-reviewed scientific conference contributions (international and foreign conferences)

Abstract: The International Fluid Power Conference is a two day event, intended for all those professionally-involved with hydraulic or pneumatic power devices and for all those, wishing to be informed about the ‘state of the art’, new discoveries and innovations within the field of hydraulics and pneumatics. The gathering of experts at this conference in Maribor has been a tradition since 1995, and is organised by the Faculty of Mechanical Engineering at the University of Maribor, in Slovenia. Fluid Power conferences are organised every second year and cover those principal technical events within the field of fluid power technologies in Slovenia, and throughout this region of Europe. This year's conference is taking place on the 14th and 15th September in Maribor. We wish all participants at the International Conference-Fluid Power 2017 continued successful professional work, and hope that we have yet again added another small piece within the mosaic of fluid power.
Keywords: fluid power technology, components and systems, control systems, fluids, maintenance, monitoring
Published: 28.09.2017; Views: 548; Downloads: 58
.pdf Full text (19,00 MB)
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6.
Analysis of the effect of the swirl flow intensity on combustion characteristics in liquid fuel powered confined swirling flames
Marko Klančišar, Tim Schloen, Matjaž Hriberšek, Niko Samec, 2016, original scientific article

Abstract: This article examines the implementation of CFD technology in the design of the industrial liquid fuel powered swirl flame burner. The coupling between the flow field and the combustion model is based on the eddy dissipation model. The choice of the LES (Large Eddy Simulation) turbulence model over standard RANS (Reynolds Averaged Navier-Stokes) offers a possibility to improve the quality of the combustion-flow field interaction. The Wall Adapting Local Eddy-Viscosity (WALE) sub-grid model was used. The reaction chemistry is a simple infinitely fast one step global irreversible reaction. The computational model was setup with the Ansys-CFX software. Through the detailed measurements of industrial size burner, it was possible to determine the natural operational state of the burner according to the type of fuel used. For the inlet conditions, axial and radial velocity components were calculated from known physical characteristics of both the fuel and air input, with the initial tangential velocity of the fuel assumed as 18% of the initial axial fuel velocity. Different swirl number (S) values were studied. Addition of a surplus (in comparison to conventional flame stabilization) of tangential air velocity component (W), the rotational component increases itself with a considerably high magnitude, contributing to the overall flame stabilization. The level of S especially influences the turbulent energy, its dissipation rate and turbulent (Reynolds) stresses. In the case of high swirl number values (S > 0,65) it is possible to divide the flow field in three principle areas: mixing area (fuel-air), where exothermal reactions are taking place, central recirculation area and outer recirculation area, which primarily contains the flow of burnt flue gases. The described model was used to determine the flow and chemical behavior, whereas the liquid atomization was accounted for by LISA (Linear Instability Sheet Atomization) model incorporating also the cavitation within injection boundary condition. The boundary conditions were determined based on the data from the experimental hot water system. Depending on system requirements, especially with continuous physical processes as well as the results of experimental measurements, the paper reports on determination of the mixing field and its intensity in the turbulent flow, the description of heat release and interaction of turbulent flow field and chemical kinetics in the case of confined swirling flames.
Keywords: CFD, fluid dispersion, combustion, industrial burner, confined swirling flame, two-phase flow
Published: 04.08.2017; Views: 772; Downloads: 293
.pdf Full text (1,08 MB)
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7.
Assessment of magnetic fluid losses out of magnetic properties measurement
Miloš Beković, Irena Ban, Anton Hamler, 2010, published scientific conference contribution

Abstract: In this paper an improved measurement system for experimental assessment of magnetic fluid losses is presented. When fluid is exposed to AC magnetic field, three different losses mechanisms are active; relaxation, hysteresis and resonance mechanism. In this paper not individual contributions where studied but combine acting which can be determine as specific power losses (SPL). SPL of the sample is obtained for a variety of amplitudes and frequencies of magnetic field with presented method of measurement of field parameters where results revealed f H2 dependence for fixed temperature of the sample. Temperature dependence of SPL is examined with calorimetrical measurements, where heating of magnetic fluid at fixed value of applied field and various frequencies is examined and results revealed linearly decreasing temperature dependence.
Keywords: magnetic fluid loss, magentic field, hysteresis loop
Published: 30.06.2017; Views: 537; Downloads: 280
.pdf Full text (495,15 KB)
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8.
RAZVOJ METODE ZA DOLOČEVANJE VISKOZNOSTI SUBSTANC V SISTEMIH S SUPERKRITIČNIMI FLUIDI
Marjan Horvat, 2016, undergraduate thesis

Abstract: Uporaba superkritičnih fluidov vse bolj narašča. V literaturi najdemo veliko podatkov o obnašanju sistema pri določenih pogojih. Zelo malo pa je podatkov za dvofazne sisteme, ki so zelo pomembni za načrtovanje novih industrijskih postopkov. Tako smo v diplomskem delu preizkusili do sedaj neuporabljeno metodo določanja viskoznosti sistema polietilen glikol/CO2 pri različnih tlakih in z različnimi molskimi masami polietilen glikola ter ugotovili, kako oba dejavnika vplivata na viskoznost sistema. Omenjen sistem PEG/CO2 smo preučevali v tlačnem območju od 10 MPa do 35 MPa, pri konstantni temperaturi 333 K. Ugotovili smo, da se gostota sistema PEG/CO2 obnaša kot funkcija tlaka. Vpliv molske mase je precej manjši. Iz diagramov viskoznost/tlak za različne molske mase polietilen glikola je razvidno, da je zmanjšanje viskoznosti bolj izrazito pri nižjih tlakih.
Keywords: superkritični fluid, ogljikov dioksid, polietilen glikol, viskoznost
Published: 25.10.2016; Views: 1155; Downloads: 61
.pdf Full text (4,47 MB)

9.
Povezava virtualnega krmilja z elektro-pnevmatskim transportnim sistemom
Tomaž Rodošek, 2016, undergraduate thesis

Abstract: Procesna avtomatizacija, doba v kateri se nahajamo, omogoča zelo visok standard kvalitetne izdelave, boljšo organizacijo in večjo produktivnost. Zato bi radi preverili učinkovitost različnih načinov vodenja elektro-pnevmatskega transportnega sistema. V večini vodenje poteka s pomočjo programirljivih logičnih krmilnikov – PLK. V diplomski nalogi so predstavljeni in analizirani načini virtualnega vodenja, kjer nam software Fluid Sim opravlja delo vodenja in vizualizacije. Preverili bomo tudi zanesljivost in uporabniški vmesnik računalniškega programa KEPserver OPC, ki skrbi za komunikacijo virtualnega krmilnika z ožičenim delom elektro-pnevmatskega transportnega sistema.
Keywords: Fluid sim, elektropnevmatski sistem, Easy port, S7 200, S7 1200
Published: 23.09.2016; Views: 681; Downloads: 75
.pdf Full text (2,89 MB)

10.
MERJENJE FIZIKALNO-KEMIJSKIH IN TRANSPORTNIH LASTNOSTI SISTEMA POLIMER/SCF
Tina Kegl, 2016, undergraduate thesis

Abstract: Vedno večje zahteve po zmanjšanju negativnega vpliva na okolje in povečanju kakovosti proizvodov vodijo do pospešenih raziskav na področju razvoja novih tehnologij. Med razmeroma nove tehnologije uvrščamo visokotlačne procese s superkritičnimi fluidi, ki veljajo za okolju prijazna, zelena topila. Diplomsko delo prikazuje študijo fizikalno-kemijskih in transportnih lastnosti sistemov polimer/SCF z namenom procesiranja polimerov pri optimalnih eksperimentalnih pogojih. Preučevane lastnosti sistemov PEG 600/CO2 in Brij52/CO2 pri tlakih od 0 bar do 300 bar in temperaturah 333 K in 353 K so gostota, površinska napetost, topnost in difuzijski koeficient. Gostota sistema je določena z gostotomerom z nihajočo U-cevko in z magnetno suspenzijsko tehtnico. Površinska napetost je določena z metodo kapilarnega dviga. Magnetna suspenzijska tehtnica je bila uporabljena tudi za določanje difuzijskega koeficienta in topnosti superkritičnega CO2 v izbranih polimerih. Na osnovi analize eksperimentalno dobljenih fizikalno-kemijskih in transportnih lastnosti so določeni optimalni procesni parametri za procesiranje polimerov. Mikronizacija s superkritičnim CO2 polimera Brij52 in polimera Brij52 z zdravilno učinkovino esomeprazol je izvedena s PGSS-metodo, medtem ko je za pridobivanje polimerne pene iz Brij52 s superkritičnim CO2 uporabljena GF-metoda. V okviru diplomske naloge je izvedena tudi analiza dobljenih vzorcev po procesiranju polimerov z okoljskim vrstičnim elektronskim mikroskopom. Rezultati kažejo, da večjo topnost CO2 v talini polimera, večji difuzijski koeficient in manjšo površinsko napetost zagotavlja sistem Brij52/CO2 za vse izbrane tlake in temperature. Tlak in temperatura v avtoklavu pri mikronizaciji polimera Brij52 in polimera Brij52 z esomeprazolom ter tvorbi pene iz polimera Brij52 znašata 333 K in 150 bar. Po primerjavi dobljenih rezultatov sistema PEG 600/CO2 z razpoložljivimi rezultati iz literature ugotavljamo, da se vplivi posameznih preučevanih parametrov na fizikalno-kemijske in transportne lastnosti dobro ujemajo. Na osnovi tega lahko sklepamo, da so meritve uspešno izvedene tudi za sistem Brij52/CO2, za katerega ni ustreznih rezultatov v razpoložljivi literaturi.
Keywords: procesiranje polimerov, superkritični fluid, gostota, površinska napetost, topnost, difuzijski koeficient
Published: 08.09.2016; Views: 2061; Downloads: 1221
.pdf Full text (3,51 MB)

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