Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, Chemical EngineeringSubject: search.filters.subject.Chemical reactions

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  • Master Thesis
    Detailed Chemical Kinetic Modeling of N-Heptane Flame
    (Izmir Institute of Technology, 2018) Değirmenci, Emre; İnal, Fikret; İnal, Fikret; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    To understand the complex combustion characteristics of gasoline, n-heptane is used as one of the two major reference fuels. The emissions resulted from incomplete combustion are one of the main issues caused from usage of high amount of fossil fuels in transportation and energy generation sectors. The main purpose of this study is to model one-dimensional premixed, laminar, burner-stabilized fuel-rich n-heptane flame to understand its combustion characteristics in mainly fuel-rich conditions. Detailed chemical kinetic modeling technique was used to get high amount of information about the ignition characteristics of n-heptane and formation nature of emissions. A detailed chemical kinetic mechanism was generated by combining several mechanisms from the literature that related with possible products of fuel-rich n-heptane combustion. The detailed mechanism consists of 4185 reactions and 893 species. Validations of the model were done with various experimental data available in the literature such as premixed laminar flames and jet stirred reactors. After generating the kinetic model, detailed investigation of the n-heptane flame was done by using rate of production, reaction sensitivity and reaction pathway analyses. One of the attributes of fuel-rich flames, Polycyclic aromatic hydrocarbon (PAH) formation kinetics were also investigated. Acetylene (C2H2), propargyl radical (C3H3), and vinylacetylene (C4H4) were found as the main precursors of the first aromatic ring and PAH formation as a result of pathway and rate of production analyses. The generated model was able to predict most of the major, minor and trace components that formed in the flame that modeled. A reduced model was also generated by using directed relation graph with error propagation (DRGEP) mechanism reduction technique on the detailed mechanism. The reduced mechanism consists of 1879 reactions and 359 species. The species mole fraction predictions of detailed and reduced mechanism were very close to each other. Most of the species formed in the flame were predicted by the reduced mechanism with less computational afford than detailed mechanism.
  • Master Thesis
    Catalytic Methanol Combustion
    (Izmir Institute of Technology, 2015) Demirkaya, Emre; Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Throughout this study, the major goal is to analyze the product distribution of methanol combustion at different reaction conditions, such as, varying space velocities, different initial temperatures, on 2% Pt/Al2O3 catalyst. The catalyst support material, alumina, was prepared by using a single-step sol-gel method and platinum was added by using the impregnation method. The reaction was conducted in a tubular reactor. In this work, the maximum steady state temperature at room temperature experiment was achieved almost same within the error for 2.4 s-1 and 2.8 s-1 space velocity for fresh catalyst, and also, the conversion to CO2 during the methanol combustion reaction for all the space velocities (2.4 s-1, 2.8 s-1 and 3.1 s-1) were found to be ~100%. Another parameter that was studied was the temperatures below the room temperature. The reaction was performed at -13oC, 0oC, 7oC and 15oC temperatures. With decreasing initial temperature, the steady state temperature was also found to be decrease. This was correlated with the product distribution and with decreasing initial temperature, CO2 conversion decrement was observed.. Methyl formate was detected to be the main byproduct that was produced under all the space velocities at temperatures lower than room temperatures. The catalyst was active even at -13oC. Therefore, it showed that it could be used as a catalyst for an external heater to provide necessary heat to reach the direct methanol fuel cells operating temperature at and below room temperature. Other than the other catalysts that was investigated in literature, our catalyst does not need to heat up the reactor. Once the fuel is supplied, the system reaches the necessary operating temperature by itself. This is desirable especially in portable DMFCs. The catalytic methanol combustion system investigated in this study seems to be promising to easily replace the lithium-ion batteries for portable electronic systems, especially ones used in the military.