1. Energy intake models for intermittent operation of dead-end microfiltration filling lineJure Ravnik, Gorazd Bombek, Aleš Hribernik, Timi Gomboc, Matej Zadravec, Aleks Kapun, Grega Hrovat, Jure Gradišek, Matjaž Hriberšek, 2022, izvirni znanstveni članek Opis: In filling lines equipped with membrane separation devices in the form of filters energy,
consumption is only one of the important working parameters, the other being sustainable filter
performance in terms of separation efficiency. As the filling line is typically equipped with a valve,
intermittent operation of the filter is an important form of its use. Whereas the overall energy
consumption of the filtration process is governed by the continuous operation mode, the intermittent
mode, characterised by opening/closing of the valve, contributes most to problems of filter failure,
i.e., the breakthrough of filtered particles through the membrane. A model for determination of the
energy intake of a microfiltration membrane during the opening and closing of a valve is presented
in this work. The model is based on computational analysis of the pressure wave signals recorded
during the opening/closing of the valve using Fourier transform, and expressed in a nondimensional
filter area specific energy intake form. The model is applied to a case of constant pressure dead-end
microfiltration with three filter types: a single membrane filter, a stacked filter and a pleated filter
with filtration surface areas ranging from 17.7 cm2
to 2000 cm2. Both clean filters, as well as partially clogged filter cases are taken into account. Second order polynomial models of the energy intake are developed and evaluated based on extensive analysis of the experimental data. The analysis of energy intake results show that the largest energy intake was observed for the clean filter case. When membrane fouling occurs at the constant flow rate values it leads to larger energy intake, however,
due to a decreasing specific flow rate during fouling these values do not exceed the clean filter case.
Ključne besede: membrane filtration, water hammer effect, membrane energy intake, filter clogging
Objavljeno v DKUM: 28.03.2025; Ogledov: 0; Prenosov: 1
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2. Experimental and mathematical investigation of anaerobic granulate density via settling velocityAljaž Klasinc, Gregor Drago Zupančič, Matjaž Hriberšek, Aleš Hribernik, Aleksandra Lobnik, Matej Zadravec, 2022, izvirni znanstveni članek Opis: The objective of this study was to determine the density of anaerobic granules on different
heights of a full-scale Upflow Anaerobic Sludge Bed reactor. The density was defined through the
settling velocities of anaerobic granules, measured in a full-scale Upflow Anaerobic Sludge Bed
reactor. In this study, granular density was calculated with the measured settling velocities and
developed mathematical model. The developed mathematical model is based on the Stokes model.
In the experiment, granules were taken from different heights of an Upflow Anaerobic Sludge Bed
reactor, from 0.6 to 7.6 m. The granules’ diameters varied between 1 and 5 mm. The granules were
taken from six different heights through the reactor. The settling velocity of the active granules
(with gas in the granule pore and on the surface of the granule) was measured first. After the active
granules’ settling velocity measurement, the granules were placed in a vortex to obtain degassed
granules (granules without any gas in the pores or on the surface), for which the settling velocities
were also measured later. It is shown that granules’ densities at different heights are independent of
the reactor height.
Ključne besede: Upflow Anaerobic Sludge Bed reactor, microstructure, anaerobic granular sludge, settling velocity, density
Objavljeno v DKUM: 26.03.2025; Ogledov: 0; Prenosov: 5
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3. Hidroenergetski sistemiIgnacijo Biluš, 2024 Opis: Skripta obravnava hidroenergetske sisteme. V uvodu so podane temeljne značilnosti oskrbe z energijo v Sloveniji, nato so predstavljeni obnovljivi viri energije in hidroenergija. Temu sledita poglavji o hidrologiji in hidroelektrarnah. V slednjem je podana osnovna razdelitev hidroelektrarn in predstavljen način njihovega delovanja. Na integralni ravni so obravnavani tudi energijski parametri vodnih turbin. Ločena poglavja so namenjena obravnavi konvencionalnih vodnih turbin in njihovih obratovalnih karakteristik. Zadnje poglavje obravnava pojav kavitacije v vodnih turbinah. Definirane so pojavne oblike glede na vrsto vodne turbine in vpliv tega pojava na integralne obratovalne karakteristike.
Ključne besede: obnovljivi viri energije, hidroelektrarne, vodna turbina, obratovalne karakteristike, kavitacija
Objavljeno v DKUM: 22.11.2024; Ogledov: 0; Prenosov: 27
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4. Sistem za umerjanje merilnikov pretoka vode : diplomsko deloKlemen Breznik, 2022, diplomsko delo Opis: Diplomsko delo obravnava umerjanje merilnika pretoka vode. Njegove tehnične specifikacije so dvomljive, saj proizvajalec navaja zgolj približno število pulzov na liter, v temperaturnem območju vode pri 20°C. Obenem tlak v sistemu in orientacija merilnika pretoka nista definirana. Umerjanje smo izvedli s pomočjo tehtnice in vzporednega zajemanja signalov merilnika pretoka v različnih položajih. Meritve so se izvajale s pomočjo programske opreme LabVIEW. Med izvajanjem meritev je bila naloga merilca zgolj pozicioniranje merilnika in zagon programa. Ugotovili smo, da orientacija bistveno ne vpliva na vrednosti pretoka, vendar je opaženo odstopanje med našimi meritvami in specificiranimi vrednostmi.
Ključne besede: Merilnik pretoka, voda, umerjanje, računalniško zajemanje signalov, DAQ, LabVIEW, RS-232.
Objavljeno v DKUM: 05.03.2024; Ogledov: 191; Prenosov: 27
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5. Development of an experimental Dead-End microfiltration layout and process repeatability analysisGorazd Bombek, Luka Kevorkijan, Grega Hrovat, Drago Kuzman, Aleks Kapun, Jure Ravnik, Matjaž Hriberšek, Aleš Hribernik, 2024, izvirni znanstveni članek Opis: Microfiltration is an important process in the pharmaceutical industry. Filter selection and validation is a time-consuming and expensive process. Quality by design approach is important for product safety. The article covers the instrumentalization and process control of a laboratory-scale dead-end microfiltration layout. The layout is a downscale model of the actual production line, and the goal is filter validation and analysis of process parameters, which may influence filter operation. Filter size, fluid pressure, valve plunger speed, and timing issues were considered. The focus is on the identification of the most influential process parameters and their influence on the repeatability of pressure oscillations caused by valve opening. The goal was to find the worst-case scenario regarding pressure oscillations and, consequently, filter energy intake. The layout was designed as compact as possible to reduce pressure losses between the filter and valve. Valve-induced pressure oscillations proved to be prevailing over the water hammer effect. Several filters in sizes between 3.5 cm2 and 6900 cm2 were tested, and some recommendations were suggested for the reduction of energy intake of the filter and to improve the repeatability of the process.
Ključne besede: filtration, pressure oscillations, repeatability, processes, parameters
Objavljeno v DKUM: 01.02.2024; Ogledov: 425; Prenosov: 36
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6. Modelling of downscale model design and parameters for filter validation extention : zaključno poročiloMatjaž Hriberšek, Jure Ravnik, Aleš Hribernik, Jurij Iljaž, Matjaž Ramšak, Matej Zadravec, Gorazd Bombek, Timi Gomboc, 2023, končno poročilo o rezultatih raziskav Ključne besede: mechanics, porous materials, hydraulic model, mechanical properties
Objavljeno v DKUM: 03.11.2023; Ogledov: 653; Prenosov: 11 |
7. Prenova letala Boeing 727 v gostinski lokal - klimatizacija in prezračevanje : diplomsko deloFilip Tratnjek, 2022, diplomsko delo Opis: Diplomsko delo obravnava načrtovanje, izvedbo oziroma predelavo in zagon klimatizacijsko/prezračevalnega sistema na stoječem letalu. Za boljše razumevanje: letalo tipa Boeing 727(ki velja za večje potniško letalo in lahko prevaža približno 150 potnikov) je bilo razstavljeno in pripeljano v Avstrijo (Graz) iz združenih držav Amerike, da bo služilo kot luksuzna restavracija na strehi prestižnega hotela Novapark. Poleg sestave celotnega letala iz delov v celoto je tu potrebna tudi prenova notranjega dela za potrebe restavracije in klimatizacije oziroma prezračevanja. Vsebina diplomske naloge zajema obnovitvena dela prezračevanja in klimatizacije, ki sem jih opravil s pomočjo podjetja Klima center Tratnjek. Sama izvedba je bila precej zahtevna, saj lastnik letala ni želel večjih vizualnih sprememb na letalu, še posebej v notranjem delu, kjer je restavracija.
Diplomsko delo je sestavljeno iz dveh delov, in sicer prvi del je načrt in montaža prezračevanja, ki lahko tudi dogreva ali hladi, drugi del pa je sestavljen iz načrtovanja in izvedbe montaže klimatske naprave, ki služi izključno za ogrevanje ali hlajenje letala.
Ključne besede: klimatizacija, gretje, hlajenje, prezračevanje, regulacija, Boeing 727
Objavljeno v DKUM: 01.06.2022; Ogledov: 673; Prenosov: 72
Celotno besedilo (1,79 MB) |
8. Vozlišče na osnovi vodikovih tehnologij : magistrsko deloAleksander Grobin, 2021, magistrsko delo Opis: Več kot tretjino svetovnih emisij predstavljata industrija in transport, sektorja, ki ju ni mogoče v celoti elektrificirati. Kot vezni člen med obnovljivimi viri energije in brezogljično energijo se vse bolj uporablja vodik. V magistrskem delu je opisano vozlišče na osnovi vodikovih tehnologij. Električna energija se proizvaja v sončni elektrarni, ki nato v elektrolizerju proizvaja zeleni vodik oziroma vodik brez emisij toplogrednih plinov. Proizvedeni vodik se primarno uporablja za transport, v povezavi z gorivno celico pa omogoča avtonomnost vozlišča, kadar slednje ni povezano na elektroenergetsko omrežje. Za namen ogrevanja se toplota v vozlišču proizvaja v toplotnih črpalkah. Podani so tudi ekonomski izračuni vozlišča in končna cena vodika. Izračuni, modeli in simulacije vozlišča so izvedeni v programskem jeziku Python.
Ključne besede: Vodik, zeleni, vozlišče, vodikove tehnologije, Python
Objavljeno v DKUM: 14.12.2021; Ogledov: 982; Prenosov: 77
Celotno besedilo (2,03 MB) |
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