| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Show document

Title:NUMERIČNI MODEL ADSORPCIJSKEGA PROCESA PRI TOKU V KANALU
Authors:Štimec, Teodor (Author)
Hriberšek, Matjaž (Mentor) More about this mentor... New window
Ravnik, Jure (Co-mentor)
Files:.pdf DR_Stimec_Teodor_2013.pdf (2,51 MB)
MD5: B7FD08026917F8FA21E82D944EAD1EBE
 
Language:Slovenian
Work type:Dissertation (m)
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:V doktorski disertaciji je predstavljen numerični model za simulacijo adsorpcijskega procesa v kanalu, ki ima na svojih stenah nameščeno plast adsorbenta. V kanalu teče tok nosilne tekočine z zelo nizko koncentracijo adsorbata, ki se zaradi med-molekularnih sil adsorbira v plast adsorbenta. Zaradi nizke koncentracije adsorbata v nosilnem mediju le ta ne vpliva na tokovne razmere v kanalu, ampak je vključen le v adsorpcijski proces. Simulacija toka tekočine v kanalu je izvedena z reševanjem sistema Navier-Stokesovih ohranitvenih enačb, ki so diskretizirane z metodo robnih elementov. Adsorpcijski prenos snovi adsorbata iz glavnine tekočine v plast adsorbenta je modeliran s prilaganjem vrednosti robne koncentracije. Koncentracija adsorbata se ob medfazni površini v tekočini in nad plastjo adsorbenta namreč zaradi adsorpcijskih procesov znižuje, kar povzroči nastanek koncentracijskega gradienta v smeti proti plasti adsorbenta in z njim povezan snovni tok. Vrednost robne koncentracije je odvisna od porazdelitvenega koeficienta, oziroma razmerja med akumulirano ter ravnotežno množino adsorbata v plasti adsorbenta. Ravnotežna množina adsorbata v plasti adsorbenta je določena s primernim ravnotežnim modelom, ki podaja omenjene vrednosti na podlagi temperature in koncentracije adsorbata ter snovnih lastnosti dostopnih v literaturi. V numerični shemi so sicer bili uporabljani štirje različni ravnotežni modeli in sicer Freundlichov, Dubinin-Radushkevichev ter SLD ravnotežna modela na osnovi Van der Waalsove ter Peng-Robinsonove enačbe stanja. Z izdelanim numeričnim modelom je bila nato izvedena vrsta simulacij toka revne mešanice zraka ter butana v kanalu, ki je imel na stenah nameščeno plast aktivnega oglja. Na podlagi rezultatov simulacij so bile izvedene: analiza primernosti računske mreže, analiza primernosti časovnega koraka ter primerjava rezultatov z referenčnimi rezultati drugih avtorjev. Primerjava rezultatov kaže, da izdelana numerična rutina omogoča natančno simuliranje adsorpcijskih procesov v kanalu. V zaključku sta bili izvedeni še parametrični analizi vpliva hitrosti ter temperature na adsorpcijski proces v kanal ter podane smernice za nadaljnjo raziskovalno delo.
Keywords:adsorpcija, ravnotežni model, SLD ravnotežni model, adsorpcijsko satovje, adsorpcija v kanalu, metoda robnih elementov, računska dinamika tekočin
Year of publishing:2013
Publisher:T. Štimec]
Source:[Maribor
UDC:544.723:519.61/.64(043.3)
COBISS_ID:268108288 New window
NUK URN:URN:SI:UM:DK:P3N0ELV4
Views:1725
Downloads:170
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:KTFMB - FS
:
  
Average score:(0 votes)
Your score:Voting is allowed only for logged in users.
Share:AddThis
AddThis uses cookies that require your consent. Edit consent...

Hover the mouse pointer over a document title to show the abstract or click on the title to get all document metadata.

Secondary language

Language:English
Title:NUMERICAL MODEL OF ADSORPTION PROCESS IN THE CHANNEL
Abstract:In this doctoral dissertation a numerical model is presented for simulation of an adsorption process in a honeycomb channel that has a thin layer of adsorbent on its walls. In the channel there is a flow of carrying fluid with very low concentration of adsorbate, which accumulates in the adsorbent layer on channel walls due to adsorption forces. Because the concentration of adsorbate in the carrying flow is very low it has no influence on the general flow conditions and it is only involved in adsorption process. Simulation of flow in the channel is made by solving Navier-Stokes system of conservation equations with the use of boundary element method. Adsorption mass flow from the bulk fluid to the layer of adsorbent is modelled with the correction of values of adsorbate concentration on the channel wall. Concentration of adsorbate near the phase surface in the fluid and above the adsorbent layer gets lowered due to adsorption process and this causes concentration gradient and adsorbate mass flux in the direction towards the channel wall. Value of wall concentration of adsorbate depends on the distribution coefficient that is governed by the ratio of accumulated mass of adsorbate in the layer and equilibrium mass of adsorbate in the adsorbent layer. Equilibrium mass of adsorbate per volume of adsorbent is calculated with an appropriate equilibrium model on the basis of known values of temperature, concentration of adsorbate and other material properties available from the literature. Four different equilibrium models were used and this were: Freundlich and Dubinin-Radushkevich equations, SLD equilibrium model based on Van der Waals equation of state and Peng-Robinson SLD equilibrium model. Presented numerical scheme was then used to perform a larger number of different simulations for a problem of channel flow of poor mixture of air and butane. Channel walls were covered with thin layer of active carbon. Based on the simulations results an analysis of suitable calculation mesh, suitable simulation time step and comparison with benchmark results from other authors were made. This comparison shows that presented numerical scheme offers good results and enables accurate simulations of adsorption processes in channels. At the end the parametrical analysis of flow rate and temperature influence on the adsorption process in a channel is made and future research guidelines are given.
Keywords:adsorption, equilibrium model, SLD equilibrium model, adsorption honeycomb, adsorption process in a channel, boundary element method, computational fluid dynamics


Comments

Leave comment

You have to log in to leave a comment.

Comments (0)
0 - 0 / 0
 
There are no comments!

Back
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica