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Keywords: School of Environmental Sciences First degree programme Second degree programme Written by Matjaz Valant Translated by Milena Kovacevic
Published in RUNG: 12.02.2018; Views: 3208; Downloads: 0
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Abstract: Iridium based particles as the most promising proton exchange membrane electrolyser electrocatalysts were investigated by transmission electron microscopy (TEM), and by coupling of electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometer (ICP-MS). Additionally, a thin-film rotating disc electrode (RDE), an identical location transmission and scanning electron microscopy (IL-TEM and IL-SEM) as well as an X-ray absorption spectroscopy (XAS) studies have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that iridium particles dissolved already well below oxygen evolution reaction (OER) potentials, presumably induced by iridium surface oxidation and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile type IrO2 particles (T-IrO2) are substantially more stable and less active in comparison to as prepared metallic (A-Ir) and electrochemically pretreated (E-Ir) analogues. Interestingly, under OER relevant conditions E-Ir particles exhibit superior stability and activity owing to the altered corrosion mechanism where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance, electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low temperature electrochemical hydrogen production device, namely a proton exchange membrane electrolyser.
Keywords: Iridium Oxide Par-ticles, Electrochemical Dissolution of Iridium, Ir L3-edge XANES
Published in RUNG: 23.08.2017; Views: 3904; Downloads: 0
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Abstract: V diplomskem delu smo prikazali, kako lahko s frekvenčno vodeno črpalko na demonstracijskem hidravličnem sistemu s spremembo moči delovanja motorja privarčujemo električno energijo in pri tem prečrpamo določeno količino vode do uporabnika, v našem primeru radiatorja. Del diplomske naloge je posvečen vrednotenju hidravličnega sistema v podjetju Kolektor Sisteh d.o.o. Vrednotenje hidravličnega sistema primerja izračune na podlagi podatkov proizvajalca črpalke, ki smo jo uporabili v našem modelu hidravličnega sistema in meritve na demonstracijskem hidravličnem sistemu pri frekvencah vrtenja črpalke 40 Hz, 45 Hz in 50 Hz, in pri 25 %, 50 %, 75 % in 100 % največjega pretoka skozi ventil. Dobljene rezultate smo prikazali v različnih tabelah in grafih, s katerimi smo kasneje določili delovne točke črpalke v demonstracijskem hidravličnem sistemu. Po dobljenih meritvah smo lahko primerjali učinkovitosti črpalke, in sicer najprej energetsko, potem pa tudi njeno ekonomsko učinkovitost. Ugotovili smo, da je delovanje črpalke pri frekvenci 40 Hz, v primerjavi s frekvencama 45 Hz in 50 Hz, energetsko in ekonomsko bolj učinkovito.
Keywords: demonstracijski hidravlični sistem, modeliranje, centrifugalna črpalka, delovna točka, energetska učinkovitost črpalke, ekonomska učinkovitost
Published in RUNG: 08.07.2015; Views: 5766; Downloads: 280
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Keywords: biomonitoring, živo srebro, izpostavljenost, doječe matere, diplomske naloge
Published in RUNG: 15.10.2013; Views: 6642; Downloads: 518
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