Modelling of an Electrochlorination Cell for Water Disinfection
Authors
Andersen, Nikolaj Kortbek ; Hedensted, Lau ; Stroe, Rodica Elisabeta
Term
4. term
Education
Publication year
2016
Submitted on
2016-05-25
Pages
155
Abstract
Hypoklorit (et klorbaseret desinfektionsmiddel) kan fremstilles på stedet ved elektrolyse til hurtig og pålidelig vandbehandling. Dette arbejde opbygger og tester en computerbaseret model af en udelt elektroklorineringscelle, det vil sige en celle uden membran mellem elektroderne. Modellen, udviklet i COMSOL Multiphysics, kobler de centrale processer: elektrokemi ved elektroderne, kemiske reaktioner i væsken, transport af opløste stoffer og to-fase gas-væske-strømning, som skyldes bobledannelse og -bevægelse. Målet er en samlet model, der kan forudsige, hvordan cellen opfører sig under forskellige driftsbetingelser. For at beskrive de gasbobler, der dannes og bevæger sig gennem cellen, udføres forsøg med direkte billeddannelse, som registrerer skyggebilleder og gør det muligt at bestemme boblestørrelse, gasvolumenfraktion (andelen gas i væsken) og boblehastighed. Modellen valideres ved at sammenholde dens resultater med disse boblemålinger og med testcellens polariseringskurve, som beskriver sammenhængen mellem spænding og strøm. Derudover gennemføres en følsomhedsanalyse for at se, hvordan ændringer i inputparametre påvirker resultaterne. Endelig undersøges en konfiguration med mindre elektrodeafstand og højere cellespænding, som i højere grad ligner industrielle anvendelser.
Hypochlorite (a chlorine-based disinfectant) can be produced on site by electrolysis to treat water quickly and reliably. This thesis builds and tests a computer model of an undivided electrochlorination cell, meaning a setup without a membrane separating the electrodes. The model, developed in COMSOL Multiphysics, links the key processes: electrochemistry at the electrodes, chemical reactions in the liquid, transport of dissolved species, and two-phase gas–liquid flow driven by bubble formation and motion. The goal is a comprehensive model that can predict how the cell performs under different operating conditions. To describe the gas bubbles that form and move through the cell, experiments use direct imaging that records shadow images, allowing determination of bubble size, gas volume fraction (the share of gas in the liquid), and bubble velocity. The model is validated by comparing its results with these bubble measurements and with the test cell’s polarization curve, which shows the relationship between voltage and current. A sensitivity analysis is then used to see how changes in input parameters influence the results. Finally, a configuration with a smaller gap between electrodes and a higher cell voltage is investigated to resemble industrial applications more closely.
[This abstract was generated with the help of AI]
Keywords
Documents