Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2015
Student: FATİH AKTAŞ
Supervisor: NUREDDİN DİNLER
Open Archive Collection: AVESIS Open Access Collection
Abstract:In this study the effect of heating before catalytic converter on efficiency of converter is examined numerically. Catalytic converter is modeled taking into account flow in a single channel. After calculations in the channel, it is determined that flow is laminar. As a channel geometry, three different models which are square cross-section, equilateral triangular cross- section and circular cross-section with fixed hydraulic diameters were used. Besides that porous volume possessed by channel is defined while channels are modeled. In the process of analysis, commercial ANSYS FLUENT software was used. Initially, single step methane- air volumetric combustion reaction was solved. After this analysis, it is stated that efficiency is very low and this results are not compatible with real results. Then, composed of four and twenty four step surface reduction reactions which are written outside and imported to software were defined. As boundary conditions of the problem, 523K, 623K and 723K which exhaust gases can reach after pre-heating in cold start condition were defined as inlet temperatures. In addition, since wall temperature is an important variable in the cold working conditions of system, analyses were done defining different temperatures. As a result of this analyses, with applied pre-heating on exhaust gases in cold start of engine, an increment in methane conversion efficiency of catalytic converter and releasing less to the environment with reaching faster to the working temperature with 50% efficiency (light-off temperature) were observed. Because hydraulic diameters are constant in used three different cross sections, methane consumption percentage does not change distinctively. In addition, with increasing of reduction reactions from single step to twenty four step, even at low temperatures, it is seen that model works correctly.