Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 3Citation - Scopus: 4Detailed Chemical Kinetic Modeling of Fuel-Rich N-Heptane Flame(Elsevier, 2020) Değirmenci, Emre; Alazreg, Abdalwahab; İnal, FikretThe main purpose of this study is to model one-dimensional, premixed, laminar, burner-stabilized, fuel-rich n-heptane flame to understand its combustion characteristics. Detailed chemical kinetic modeling technique was used to obtain more information about the formation nature of emissions in n-heptane flame. 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 mechanism consists of 4185 reactions and 893 species. Validations of the mechanism were done by species mole fractions of premixed laminar flames and jet stirred reactors, and ignition delay times in shock tubes. A detailed investigation of the n-heptane flame was carried out using rate of production and reaction pathway analyses. Propargyl radical (C3H3), vinylacetylene (C4H4) and acetylene (C2H2) were found as the main precursors of benzene formation. The mechanism was able to predict most of the major, minor, and trace species up to four-fused aromatic rings formed in the flame. A skeletal mechanism was also generated using Directed Relation Graph with Error Propagation (DRGEP) method. It consists of 1879 reactions and 359 species. The skeletal mechanism was in a good agreement with the detailed mechanism on the species mole fraction predictions.Article Citation - WoS: 20Citation - Scopus: 26Pops in a Major Conurbation in Turkey: Ambient Air Concentrations, Seasonal Variation, Inhalation and Dermal Exposure, and Associated Carcinogenic Risks(Springer Verlag, 2016) Ugranlı, Tuğba; Güngörmüş, Elif; Kavcar, Pınar; Demircioğlu, Eylem; Odabaşı, Mustafa; Sofuoğlu, Sait Cemil; Lammel, Gerhard; Sofuoglu, AysunSemi-volatile organic compounds were monitored over a whole year, by collection of gas and particle phases every sixth day at a suburban site in Izmir, Turkey. Annual mean concentrations of 32 polychlorinated biphenyls (∑32PCBs) and 14 polycyclic aromatic hydrocarbons (∑14PAHs) were 348 pg/m3 and 36 ng/m3, respectively, while it was 273 pg/m3 for endosulfan, the dominant compound among 23 organochlorine pesticides (OCPs). Monte Carlo simulation was applied to the USEPA exposure-risk models for the estimation of the population exposure and carcinogenic risk probability distributions for heating and non-heating periods. The estimated population risks associated with dermal contact and inhalation routes to ∑32PCBs, ∑14PAHs, and some of the targeted OCPs (α-hexachlorocyclohexane (α-HCH), β-hexachlorocyclohexane (β-HCH), heptachlor, heptachlor epoxide, α-chlordane (α-CHL), γ-chlordane (γ-CHL), and p,p′-dichlorodiphenyltrichloroethane (p,p′-DDT)) were in the ranges of 1.86 × 10−16–7.29 × 10−9 and 1.38 × 10−10–4.07 × 10−6, respectively. The inhalation 95th percentile risks for ∑32PCBs, ∑14PAHs, and OCPs were about 6, 3, and 4–7 orders of magnitude higher than those of dermal route, respectively. The 95th percentile inhalation risk for ∑32PCBs and OCPs in the non-heating period were 1.8- and 1.2–4.6 folds higher than in the heating period, respectively. In contrast, the 95th percentile risk levels for ∑14PAHs in the heating period were 4.3 times greater than that of non-heating period for inhalation, respectively. While risk levels associated with exposure to PCBs and OCPs did not exceed the acceptable level of 1 × 10−6, it was exceeded for 47 % of the population associated with inhalation of PAHs with a maximum value of about 4 × 10−6.Article Citation - WoS: 19Citation - Scopus: 23Artificial Neural Network Predictions of Polycyclic Aromatic Hydrocarbon Formation in Premixed N-Heptane Flames(Elsevier Ltd., 2006) İnal, FikretPolycyclic aromatic hydrocarbon formation in combustion systems has received considerable attention because of its health effects. The feed-forward, multi-layer perceptron type artificial neural networks with back-propagation learning were used to predict the total PAH amount in atmospheric pressure, premixed n-heptane and n-heptane/oxygenate flames. MTBE and ethanol were used as fuel oxygenates. The total fifty-four data sets were divided into three groups: training, cross-validation, and testing. The different network architectures were tested and the best predictions were obtained for a network of one hidden layer with five neurons. The transfer function was sigmoid function. The mean square and mean absolute errors were 10.52 and 2.60 ppm for the testing set, respectively. The correlation coefficient (R2) was 0.98. The results also showed that the total PAH amount was significantly influenced by the changes in equivalence ratio, presence of fuel oxygenates, and mole fractions of C4 species.Article Citation - WoS: 220Citation - Scopus: 234Determination of Octanol-Air Partition Coefficients and Supercooled Liquid Vapor Pressures of Pahs as a Function of Temperature: Application To Gas-Particle Partitioning in an Urban Atmosphere(Elsevier Ltd., 2006) Odabaşı, Mustafa; Çetin, Eylem; Sofuoğlu, AysunOctanol-air partition coefficients (KOA) for 14 polycyclic aromatic hydrocarbons (PAHs) were determined as a function of temperature using the gas chromatographic retention time method. log KOA values at 25° ranged over six orders of magnitude, between 6.34 (acenaphthylene) and 12.59 (dibenz[a,h]anthracene). The determined KOA values were within factor of 0.7 (dibenz[a,h]anthracene) to 15.1 (benz[a]anthracene) of values calculated as the ratio of octanol-water partition coefficient to dimensionless Henry's law constant. Supercooled liquid vapor pressures (PL) of 13 PAHs were also determined using the gas chromatographic retention time technique. Activity coefficients in octanol calculated using KOA and PL ranged between 3.2 and 6.2 indicating near-ideal solution behavior. Atmospheric concentrations measured in this study in Izmir, Turkey were used to investigate the partitioning of PAHs between particle and gas-phases. Experimental gas-particle partition coefficients (Kp) were compared to the predictions of KOA absorption and KSA (soot-air partition coefficient) models. Octanol-based absorptive partitioning model predicted lower partition coefficients especially for relatively volatile PAHs. Ratios of measured/modeled partition coefficients ranged between 1.1 and 15.5 (4.5±6.0, average±SD) for KOA model. KSA model predictions were relatively better and measured to modeled ratios ranged between 0.6 and 5.6 (2.3±2.7, average±SD).Article Citation - WoS: 24Citation - Scopus: 25Mass Transfer Coefficients for Polycyclic Aromatic Hydrocarbons (pahs) To the Water Surface Sampler: Comparison To Modeled Results(Elsevier Ltd., 2001) Odabaşı, Mustafa; Sofuoğlu, Aysun; Holsen, Thomas M.A sampling program was conducted between June and October 1995 in Chicago, IL using a modified water surface sampler (WSS) and dry deposition plates to measure the particulate dry deposition and gas exchange of PAHs. Oxygen transfer experiments were also conducted to evaluate the collection properties of the WSS for gas-phase compounds. Gas-phase fluxes were determined by subtracting the dry deposition plate fluxes (particulate) from WSS fluxes (particulate+gas). These fluxes were divided by concurrently measured ambient concentrations to obtain overall gas phase mass transfer coefficients. Two different two-film models, one developed based on experiments performed with the WSS and, one previously published, were compared to these results. Experimentally determined average gas phase overall mass transfer coefficient (Kg) for seven PAHs was 0.74±0.52cms-1. Experimental Kg values agreed well with those predicted by the model developed for WSS. The values predicted by previously proposed models were within a factor of 3 of the experimental ones.