Browsing by Author "Guelcan, Mehmet"

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Effects of Boron-Based Additives on Combustion Characteristics, Emission Reduction, and Performance Improvement in Internal Combustion Engines
(Elsevier Sci Ltd, 2025) Yakin, Ahmet; Guelcan, Mehmet
This study examines the impact of methylamine-borane (MAB), a hydrogen-enriched fuel additive, on the combustion dynamics, emission characteristics, and performance metrics of gasoline engines. The evaluation was conducted at volumetric concentrations of 5 % (MAB5) and 10 % (MAB10). The results indicated a substantial reduction in carbon monoxide (CO) emissions by 76.79 % for MAB5 and 66.39 % for MAB10, as well as a decrease in hydrocarbon (HC) emissions by 21.39 % and 35.39 %, respectively. Carbon dioxide (CO2) emissions were also reduced by 15.29 % for MAB5 and 9.76 % for MAB10, suggesting an improvement in combustion efficiency. However, an increase in nitrogen oxides (NOx) emissions was observed, likely due to higher peak combustion temperatures. Elevated oxygen (O2) levels in the exhaust were noted, reflecting alterations in in- cylinder oxygen dynamics and combustion stoichiometry. Performance analysis revealed that MAB use resulted in higher brake-specific fuel consumption (BSFC) and lower thermal efficiency, with reductions of 7.69 % and 9.93 % for MAB5 and MAB10, respectively, attributable to the lower energy density of MAB relative to gasoline. A decrease in exhaust gas temperature was observed, suggesting a complex interaction of energy release and heat transfer processes. Despite the reduction in emissions, the increase in NOx formation highlights the intensification of combustion phases and greater thermal stress within the engine cylinder. The findings suggest that MAB, as a hydrogen-enriched fuel additive, offers notable benefits in emission reduction, but presents challenges such as reduced performance efficiency and increased thermal management requirements. These results underscore the need for optimizing additive formulations and operational parameters to balance the emission reduction potential with performance efficiency in gasoline engine applications.
Ohmic and Rectifier Properties of Al/Ligand(n-apth) and Al/Cu(ii)complex Contacts
(Elsevier, 2010) Temirci, Cabir; Guelcan, Mehmet; Goksen, Kadir; Soenmez, Mehmet
We have produced a Ligand(N-APTH) and Cu(II)Complex of bidentate ligand containing a ring of the pyrimidine. Optical transmission measurements of the Ligand(N-APTH) and Cu(II)Complex thin films were performed by using a UV-Visible (UV-VIS) spectrophotometer. From the optical measurements, it was seen that the materials show semiconductor behaviors giving appropriate bandgaps with the values of 3.15 eV and 2.36 eV for Ligand(N-APTH) and Cu(II)Complex, respectively. With the pre-assumption that the material may exhibit a rectifier or ohmic behavior when it is brought into an appropriate contact with a metal, an attempt to explore the rectifying and ohmic properties of Al/Ligand(N-APTH)/Cu and All Cu(II)Complex/Cu contacts was made. As a result of current-voltage (I-V) measurements, it was discovered that the devices show excellent rectifier properties with a rectification ratio of about 10(-3) for All Ligand(N-APTH)/Cu and 10(-5) for Al/Cu(II)Complex/Cu rectifier contacts, respectively. (C) 2010 Elsevier B.V. All rights reserved.
Rh Nanoparticles-Decorated Graphene Oxide: an Efficient Catalyst for the Hydrogenation of Nitroaromatic Pollutants
(Springer, 2024) Eftekhari Sis, Bagher; Pishghadam, Neda; Ruezgar, Adem; Guelcan, Mehmet
Amine-functionalized graphene oxide (GO-NH2) was prepared by synthesizing graphene oxide (GO) using the Hummer's method, followed by reacting with (3-aminopropyl)triethoxysilane (APTES). The obtained GO-NH2 was utilized for immobilizing and stabilizing Rh(0) nanoparticles (NPs) to create Rh@GO-NH2 material. The synthesized Rh@GO-NH2 material was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), elemental mapping, and X-ray photoelectron spectroscopy (XPS) analysis. The results indicated that the Rh(0) NPs were successfully decorated on the GO-NH2 surface. The catalytic activity of Rh@GO-NH2 was examined for the hydrogenation of nitroaromatic compounds using NaBH4 as a reducing agent. Results demonstrated that Rh@GO-NH2 effectively catalyzed the hydrogenation of nitroaromatics into the corresponding aniline derivatives in aqueous media at a moderate temperature. Nitroaromatic compounds are considered high toxic water contaminants. The simple preparation of the catalyst, low catalyst loading, and the recoverability of the catalyst are some advantages of this work.