Napovedovanje hitrostnih profilov za dvofazni sistem v mikrokanalu za segmentiran tok z uporabo metode končnih elementov

Vuzem, Marko (avtor), Plazl, Igor (mentor)

V uvodnem delu magistrskega dela predstavljamo segmentirani tok na področju mikrofluidike, ki ponuja številne prednosti pred drugimi tokovnimi režimi, predvsem zaradi visokega koeficienta masnega transporta in izboljšanega prenosa toplote. Zaradi visoke specifične in medfazne površine je hkrati zelo učinkovit za reakcijske sisteme, ki jih izvajamo na mikroskali. Modeliranje mikrofluidnih procesov postaja z napredkom računalniških zmogljivosti ključni element načrtovanja reakcijskih izvedb, saj so eksperimentalne postavitve na mikroskali drage in kompleksne, poleg tega pa je po začetni postavitvi težko regulirati določene parametre znotraj sistema. S pomočjo numeričnih simulacijskih orodij lahko hitreje, enostavneje in ceneje določimo primerne geometrije kanalov, obratovalne parametre in druge spremenljivke za čim bolj učinkovito eksperimentalno izvedbo. V magistrskem delu smo preiskovali vpliv različnih geometrij mikrokanalov na tvorbo segmentiranega toka v dvofaznem sistemu kapljevina-kapljevina. Pridobljene tokovne profile smo obravnavali numerično z metodama level-set in FEM ter določili optimalne hitrosti posameznih faz, prav tako pa opredelili vpliv geometrije kanala na tvorbo toka. Med najbolj ugodne geometrije kanalov za tvorbo segmentiranega toka so se izkazale geometrije, ki so imele daljši in ožji glavni kanal. Manj obetavne so geometrije mikrokanalov, ki imajo širše in krajše glavne kanale. Preizkušali smo tudi vpliv vpeljave ovir za dosego kapljičnega toka. Ovire so kljub manjšim izboljšavam zaradi svoje enostavnosti strukture in vpeljave v večini primerov vseeno smiselni.

• Jezik: Slovenski jezik
• Ključne besede: segmentiran tok, dvofazni sistem, geometrija mikrokanala, metoda končnih elementov
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2023
• PID: 20.500.12556/RUL-146736
• COBISS.SI-ID: 158700803
• Datum objave v RUL: 09.06.2023

VUZEM, Marko, 2023, Napovedovanje hitrostnih profilov za dvofazni sistem v mikrokanalu za segmentiran tok z uporabo metode končnih elementov [na spletu]. Magistrsko delo. [Dostopano 5 maj 2025]. Pridobljeno s: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=slv&id=146736

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Simulation of velocity profiles of two-phase flows in a microchannel for Taylor flow using the finite element method

Izvleček

In the introductory part of this Master’s thesis we present the use of Taylor flow in the area of microfluidics, which offers many advantages in comparison to other flow regimes, mostly due to its high coefficient of mass transport and heat transfer. It is also a very efficient flow regime for carrying out chemical reactions due to its high interfacial surface area. With the recent increase of computing power, mathematical modelling of microfluidics processes is becoming a crucial part of designing microfluidic reaction systems, because microfluidics systems are often expensive and complex to set up, and parameters within the system can be difficult to regulate post initial setup. With the use of numerical tools, we are able to deduce the efficacy of microchannel geometry, operating parameters and other variables much faster, easier and at a lower cost. In this thesis we researched the effect of different microchannel geometries on the formulation of Taylor flow in a two-phase liquid-liquid system. The generated flow regimes were simulated numerically with the level-set and finite element methods. The results gave an insight into optimal parameters for the given phase velocities and also helped evaluate the effect of different microchannel geometries on the flow regime. The most promising microchannels for generating Taylor flow were microchannels with long and narrow main channels. Microchannels with shorter and wider main channels generally yielded poorer results, as they often failed to produce segmented flow and produced parallel flow instead. We also tested the implementation of separation pillars, which were intended to produce droplet flow. The pillars resulted in a minor improvement in most cases, but due to their simplicity remain a suitable addition to the microchannel geometry.

• Ključne besede: Taylor flow, two-phase system, microchannel geometry, finite element method