magistrsko delo
Anton Nahtigal (Author), Matjaž Hriberšek (Mentor), Niko Samec (Co-mentor)

Abstract

Magistrska naloga se ukvarja z nadgradnjo računskega modela za računalniško simulacijo katalitičnih pretvorb povratnega toka izpušnih plinov. Obstoječ računski model v programskem paketu AVL FIRE® je razširjen s kemijskimi reakcijami, ki opisujejo pretvorbo izooktana v vodik. Eden izmed načinov, kako zmanjšati vsebnost škodljivih zmesi v izpušnih plinih je katalitična pretvorba povratnega toka izpušnih plinov. Bistvo tega sistema je znižanje temperature zgorevanja v zgorevalni komori motorja, kar vodi v zmanjšanje deleža NOx v izpušnih plinih. Dodatno se v katalitičnih reakcijah tvori vodik, ki ugodno vpliva na proces zgorevanja: manjša nihanje tlaka med posameznimi motornimi cikli in preprečuje klenkanje motorja. Pri magistrskem delu so bile uporabljene naslednje metode: 1. pregled in preučevanje obstoječe literature, ki se ukvarja z zmanjšanjem NOx v izpušnih plinih, 2. uvedba računskega modela, ki opisuje pretvorbe snovi v katalitičnem pretvorniku zaradi dovajanja goriva, 3. izdelava računalniškega 1D modela za umerjanje kemijskih reakcij na osnovi meritev, 4. izdelava računalniškega 3D modela za simulacijo celotnega procesa vbrizgavanja goriva in katalitičnih pretvorb snovi, 5. ovrednotenje rezultatov računalniških simulacij, ter izdelava izboljšanega računskega modela, 6. primerjava in ovrednotenje rezultatov med osnovnim in izboljšanim modelom. Cilj naloge je izdelava računskega modela, ki bo uspešno napovedal količino pridelanega vodika, ter ugotovil, kateri so vplivni parametri za nastanek vodika. Iz dobljenih rezultatov je razvidno, da je količina pridobljenega vodika pri danih pogojih odvisna tudi od stopnje homogenosti koncentracije C8H18 pred vstopom v katalitični pretvornik. S pomočjo računskega modela smo uspešno izboljšali učinkovitost osnovnega modela.

Keywords

povratni tok izpušnih plinov;katalitični pretvornik;računalniška dinamika tekočin;magistrske naloge;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UM FS - Faculty of Mechanical Engineering
Publisher: [A. Nahtigal]
UDC: 004.942:621.43.068.7(043.2)
COBISS: 20180246 Link will open in a new window
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Other data

Secondary language: English
Secondary title: THE CONTRIBUTION TO THE DEVELOPMENT OF THE NUMERICAL MODEL FOR CATALYTIC CONVERSION OF THE RECIRCULATED EXHAUST GASES
Secondary abstract: The upgrade of the Computational Fluid Dynamics (CFD) numerical model for the Catalytic Exhaust Gas Recirculation system (CEGR) is presented in the Master thesis. The existing numerical model made in CFD code AVL FIRE® is extended by the chemical reactions, which describe the of isooctane into the hydrogen.. One possible method, how to reduce the content of the harmful gas mixtures is CEGR system. CEGR reduces nitrogen oxides (NOx) content in exhaust gases by reducing temperature of the combustion – residual gases have less oxygen. The essence of this system is to reduce the temperature of combustion in the combustion chamber, which leads to the reduction of the level of NOx in the exhaust gasses. In addition to that CEGR produces hydrogen from gasoline by catalytic reforming process. Hydrogen reduces the engine cycle-to-cycle variation and prevent engine nocking. For this work the following methods have been applied: 1. research and examination of the literature about NOx reduction in combustion process of the internal combustion engines, 2. implementation of the CEGR kinetic model, which describes the conversion of a species in the catalytic converter due to the injection of the fuel, 3. set-up and parameterization 1D CEGR model to calibrate the chemical reactions on the basis of measurement 4. set-up of 3D CEGR model that includes fuel injection and catalytic conversion process of the gasoline, 5. evaluation of the simulation results and optimization of the existing geometry in order to increase CEGR performance, 6. the comparison and evaluation of the results between the basic and the improved model(s). The final goal of the Master thesis is a set-up of the numerical model for accurate prediction of the hydrogen production in the fuel reforming process and to find out the parameters that influence the hydrogen yield. The results at the end of the study show that the quantity of the produced hydrogen in given conditions also depends on the degree of homogeneity of concentration of C8H18 before the entry to the catalytic converter. With the help of the computing model, we have successfully improved the performance of the basic model.
Secondary keywords: exhaust gas recirculation;catalytic converter;computational fluid dynamics;
URN: URN:SI:UM:
Type (COBISS): Master's thesis
Thesis comment: Univ. v Mariboru, Fak. za strojništvo
Pages: VIII, 62 f.
ID: 9165560