Browsing by Author "Depci, T."

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Compressive Strength of Scoria Added Portland Cement Concretes
(Gazi Univ, 2012) Ozvan, A.; Tapan, M.; Erik, O.; Efe, T.; Depci, T.
This paper presents the results of preliminary studies investigating the potential effects of using scoria as supplementary and its amount on compressive strength of concrete. Concrete mixtures containing 5, 10, 20, 30, 40 and 50 % scoria type natural pozzolan by mass of the total cementitious material were prepared. In addition, a conventional portland cement concrete mixture with the same w/cm ratio was prepared as a reference. Preliminary results indicated that the compressive strength of the concrete mixtures with scoria added up to 30% exceeded the strength of the conventional mixture at 3, 7, 28 and 91 days, whereas the compressive strength of the 40 and 50% scoria added concrete mixtures decreased at 3, 7, 28 and 91 days. It was found that early strength of scoria added (up to 30%) concrete mixtures showed higher compressive strengths up to 112%.
Effect of Carbon Nanotube Addition on the Superconducting Properties of Bscco Samples Textured Via Laser Floating Zone Technique
(Springer, 2019) Ozcelik, B.; Ergin, I; Depci, T.; Yavuz, H., I; Madre, M. A.; Sotelo, A.
In this research, the effect of carbon nanotube (CNT) addition on the structural and superconducting properties of Bi2Sr2CaCu2Oy + x wt% CNT materials with x = 0, 0.5, 1, and 3 prepared by solid state method, followed by directional grown using the laser floating zone (LFZ) technique has been investigated. XRD measurements showed that all samples are composed of almost single Bi-2212 phase. SEM images proved that Bi-2212 phase is the major one, with minor amounts of (Sr,Ca)(3)BiOx, and Bi-2201 secondary phases. According to the magnetic results, carbon nanotubes decrease T-c values and significantly reduce the magnetic hysteresis loops area and the magnetic critical current density.
Exergetic Simulation and Performance Analysis of the Effect of Flow Patterns in Pemfcs
(int Center Applied thermodynamics, 2019) Mert, S. O.; Toprak, M. M.; Depci, T.
In this study, 6 different novel flow channels of the "proton exchange membrane" (PEM) type fuel cells were designed and modeled, while evaluations were conducted on three-dimensional channels of various designs using COMSOL Multiphysics simulation software. Proposed fuel cell designs and flow channel geometries were compared to existing exergetically-efficient fuel cell designs in terms of total exergy efficiency in a 3D manner as a novel tool for fuel cell investigations. Exergy efficiency analyses were conducted on the membrane surfaces of the proposed designs in addition to the anode and cathode side exergy analyses, and exergetic efficiencies of the alternatives. It is found that Design 6 is the best flow channel design with relatively high values and homogeny in exergy efficiency. The multi-inlet/outlet style while sustaining the reaction long enough for the reactant depletion leads to high-efficiency levels as seen from the results with average efficiency of 24%.
A Study on Characterization and Use of Flotation To Separate Unburned Carbon in Bottom Ash From Cayirhan Power Plant
(Taylor & Francis inc, 2011) Ucurum, M.; Toraman, O. Y.; Depci, T.; Yogurtcuoglu, E.
In this study, bottom ash from the Tuncbilek power plant has been characterized by X-ray fluorescence, X-ray diffraction, and infrared analysis. The bottom ash sample is potentially of class C type and has unburned carbon. The unburned carbon was separated from the bottom ash in a laboratory flotation cell. In the flotation experiment, sodium silicate (as a potential dispersant and depressant), butanol (promoter), kerosene oil (collector), and pine oil (frother) were used and the optimization of these flotation reagents were done through statistical modeling using a full two-level factorial design in order to evaluate the main and interaction effects of variables in flotation of unburned carbon; the evaluation of the results was done by Yates' notation. Test results showed that a product with 45.41% combustible grade at 40.0% recovery and 94.86% ash rejection was obtained at 1.98 g/kg sodium silicate, 1.38 g/kg promoter, 4.95 g/kg collector, and 2.41 g/kg frother.