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Öğe Effects of Electrical Properties on Determining Materials for Power Generation Enhancement in TEG Modules(Springer, 2019) Ozturk, Turgut; Kilinc, Enes; Uysal, Fatih; Celik, Erdal; Kurt, HuseyinThis study aimed to increase the energy efficiency of thermoelectric generators designed by considering the electrical properties of p- and n-type semiconductor materials for reducing the costs associated with the experiments, errors, and long production processes. Accordingly, the estimation of the energy amount to be produced by the thermoelectric materials was achieved by different doping elements using three different parameters such as skin-depth, electrical conductivity and dielectric constant. Additionally, the findings were supported by experimental results. In contrast to the conventionally used black-box type approach and estimation methods, an inference was obtained on the actual values of the materials.Öğe An energy efficiency analysis of an industrial reheating furnace and an implementation of efficiency enhancements methods(Sage Publications Inc, 2014) Kilinc, Enes; Kaya, Durmus; Kilic, Fatma Canka; Eyidogan, Muharrem; Ozkaymak, Mehmet; Taylan, Osman; Pedrycz, WitoldRapid consumption of energy resources, increasing energy needs, the competitive conditions in the industry and environmental concerns, all of those call for efficient use of energy resources. In this context, energy efficiency studies were carried out in a rolling mill of a reheating furnace of an integrated industrial enterprise. In studies, some important efficiency measurements were conducted, mass and energy balances were established by using the results of these measurements and the operating data of the plant along with energy saving opportunities, with the specified amounts and repayment periods were determined. Energy conservation studies that can be realized in the reheating furnace were considered including operation of the reheating furnace with the pertinent excess air coefficient, compensation of the air leakage losses in the recuperator and establishment of the economizer in the furnace. As a result of these investigations some saving opportunities were determined and a new recuperator, economizer and gas analyzer were installed in the reheating furnace leading in total of 2,913,924 kcal/h of energy savings. After the implementation of energy saving measures, reheating furnace efficiency was increased from 61.83% to 69.43%.Öğe Estimating Seebeck Coefficient of a p-Type High Temperature Thermoelectric Material Using Bee Algorithm Multi-layer Perception(Springer, 2017) Uysal, Fatih; Kilinc, Enes; Kurt, Huseyin; Celik, Erdal; Dugenci, Muharrem; Sagiroglu, SelamiThermoelectric generators (TEGs) convert heat into electrical energy. These energy-conversion systems do not involve any moving parts and are made of thermoelectric (TE) elements connected electrically in a series and thermally in parallel; however, they are currently not suitable for use in regular operations due to their low efficiency levels. In order to produce high-efficiency TEGs, there is a need for highly heat-resistant thermoelectric materials (TEMs) with an improved figure of merit (ZT). Production and test methods used for TEMs today are highly expensive. This study attempts to estimate the Seebeck coefficient of TEMs by using the values of existing materials in the literature. The estimation is made within an artificial neural network (ANN) based on the amount of doping and production methods. Results of the estimations show that the Seebeck coefficient can approximate the real values with an average accuracy of 94.4%. In addition, ANN has detected that any change in production methods is followed by a change in the Seebeck coefficient.Öğe High performance Ca3-xAg0.3LaxCo4O9 materials for aerospace applications of thermoelectric devices(Springer, 2024) Sari, Mucahit Abdullah; Kilinc, Enes; Uysal, Fatih; Kurt, Huseyin; Celik, ErdalIn the domain of aviation applications, the utilization of thermoelectric materials holds significant importance, particularly in regions characterized by notable thermal gradients, aimed at harnessing these gradients for electricity generation. This study advocates for the adoption of thermoelectric modules, specifically within the operational contexts of fixed-wing aircraft and satellites. These settings require resilient thermoelectric systems capable of effectively exploiting temperature differentials to enable electrical power generation, thus emphasizing the necessity of integrating such modules into their operational frameworks. Accordingly, this paper systematically elucidates the production and characterization of Ca3-xAg0.3LaxCo4O9 for thermoelectric applications in the aerospace sector. Ca3-xAg0.3LaxCo4O9 ceramics are synthesized via the sol-gel method employing Ca, Ag, La, and Co precursor materials. Distilled water serves as the solvent to dissolve the precursors, yielding homogeneous solutions. These solutions undergo magnetic stirring at 100 degrees C to achieve final homogeneity, with citric acid monohydrate introduced as a chelating agent to expedite xerogel formation. pH and turbidity measurements are conducted on the prepared solutions using a pH meter and turbidimeter, respectively. Following the gelation process, the resulting xerogel is dried at 200 degrees C for 2 h to eliminate moisture and undesirable gases. Subsequently, the dried powders are calcined at 800 degrees C for 2 h, yielding the final Ca3-xAg0.3LaxCo4O9 materials. The thermal, structural, microstructural, and thermoelectric properties of the materials are comprehensively characterized utilizing DTA-TG, FTIR, XRD, XPS, SEM, and thermoelectric measurement machines. It is ascertained that the produced semiconducting ceramic materials exhibit efficient suitability for thermoelectric generator production.Öğe High temperature thermopower of sol-gel processed Zn1-x-y Al x Me y O (Me: Ga, In)(Springer, 2017) Kilinc, Enes; Demirci, Selim; Uysal, Fatih; Celik, Erdal; Kurt, HuseyinIn this study, dually doped samples of Zn1-x-y Al (x) Me (y) O (Me: Ga, In) were prepared by sol-gel process followed by hot isostatic pressing for high temperature thermoelectric applications. Material characterizations were performed with differential thermal analysis-thermogravimetry, Fourier transform infrared spectroscopy and X-ray diffraction on the target phases. Successful doping of the samples was confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray analysis. Thermopower values of the samples are found to be relatively high in analogy to semiconducting behavior in which negative values indicate electrons are the dominant charge carriers (n-type). Substitution of Zn2+ by Ga3+ and In3+ for Zn1-x-y Al (x) Me (y) O (Me: Ga, In) increases electron concentration in the samples and thereby decreases the thermopower values compared to Zn0.98Al0.02O. Considering the absolute values, In doped samples have higher thermopower (alpha (max) = -162 A mu V/K at 585 A degrees C for Zn0.96Al0.02In0.02O) compared to the Ga doped sample. Al and In dually doped Zn0.96Al0.02In0.02O could be considered as a promising n-type thermoelectric material for high temperature applications.Öğe High-Temperature Thermoelectric Properties of Sol-Gel Processed Ca2.5Ag0.3RE0.2Co4O9 (RE: Y and Rare-Earths) Materials(Wiley-V C H Verlag Gmbh, 2020) Kilinc, Enes; Uysal, Fatih; Celik, Erdal; Kurt, HuseyinHerein, dually doped Ca2.5Ag0.3RE0.2Co4O9 (RE: La, Pr, Nd, Sm, Gd, Dy, Er, Yb, Eu, Tb, Ho, Lu, Ce, and Y) samples are synthesized by sol-gel technique and consolidated by cold pressing under high pressure to systematically scrutinize the influences of Y and rare-earth dually doping with Ag on transport properties of Ca3Co4O9 for high-temperature thermoelectric (TE) applications. Characterization results reveal that targeted phase is successfully produced, and doping of the compositions is provided. Doping of Y and rare-earth elements together with Ag into the Ca2+ site is effective in increasing the Seebeck coefficient and decreasing the electrical resistivity of the samples, thanks to the reduction in carrier concentration. Thermal conductivity of the samples is reduced related to the lower relative densities and alloy scattering originated from dually doping. Among the samples, Ca2.5Ag0.3Ho0.2Co4O9 and Ca2.5Ag0.3Eu0.2Co4O9 exhibit the highest power factor (PF) values of 0.65 and 0.62 mW m(-1) K-2 at 800 degrees C, respectively. These results are quite high for bulk oxide TE materials which can be assessed as potential oxide TE materials for high-temperature TE power generation.Öğe A prediction model of artificial neural networks in development of thermoelectric materials with innovative approaches(Elsevier - Division Reed Elsevier India Pvt Ltd, 2020) Kokyay, Seyma; Kilinc, Enes; Uysal, Fatih; Kurt, Huseyin; Celik, Erdal; Dugenci, MuharremThe fact that the properties of thermoelectric materials are to be estimated with Artificial Neural Networks without production and measurement will help researchers in terms of time and cost. For this purpose, figure of merit, which is the performance value of thermoelectric materials, is estimated by Artificial Neural Networks without an experimental study. P-and n-type thermoelectric bulk samples were obtained in 19 different compositions by doping different elements into Ca2.7Ag0.3Co4O9- and Zn0.98Al0.02O-based oxide thermoelectric materials. The Seebeck coefficient, electrical resistivity and thermal diffusivity values of the bulk samples were measured from 200 degrees C to 800 degrees C with an increase rate of 100 degrees C, and figure of merit values were calculated. 7 different Artificial Neural Network models were created using 123 measured results of experimental data and the molar masses of the doping elements. In this system aiming to predict the electrical resistivity, thermal diffusivity and figure of merit values of thermoelectric materials, the average R value and accuracy rate of these values were estimated to be 94% and 80%, respectively. (c) 2020 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Öğe Production and development of ZnAlGeO semiconducting materials for thermoelectric generators in potential aerospace applications(Springer, 2024) Sari, Mucahit Abdullah; Kilinc, Enes; Uysal, Fatih; Kurt, Huseyin; Celik, ErdalThis research aims to produce and develop semiconducting thermoelectric materials for thermoelectric generators in aerospace applications. In this context, ZnAlGeO powders were synthesized via the sol-gel method using precursor materials and a 20% toluene solution in ethanol as the solvent. Glacial acetic acid was added to accelerate gel formation. The pH and turbidity values of prepared solutions were measured using a pH meter and turbidimeter. After gelation, the obtained xerogel was dried at 200 degrees C for 9 h to remove moisture and undesired gases. Dried powders were calcined at 600 degrees C for 4 h in air, resulting in final ZnAlGeO materials. The pellets underwent thermal processing for 36 h at a temperature of 1350 degrees C, targeting the production of bulk samples within the n-type semiconductor category. Extensive characterization, including thermal, structural, microstructural, and thermoelectric properties, was conducted using various techniques such as DTA-TG, FTIR, XRD, XPS, SEM, and thermoelectric measurement devices. The study concludes that the produced semiconducting ceramic materials exhibit efficiency for thermoelectric generator production. Zn1-x-yAlxGeyO (x = 0.02, 0.04, and y = 0.02, 0.04) powders were synthesized by sol-gel method and densified under high-pressure cold pressing.Effects of dual doping on thermoelectric properties of Zn1-x-yAlxGeyO (x = 0.02, 0.04, and y = 0.02, 0.04) were investigated.Thermoelectric performances of Zn1-x-yAlxGeyO (x = 0.02, 0.04, and y = 0.02, 0.04) are enhanced by dual doping.Promising Zn1-x-yAlxGeyO (x = 0.02, 0.04, and y = 0.02, 0.04) oxide materials for energy harvesting and conversion technologies, particularly in aerospace applications.Öğe Steady-state thermal-electric analysis of a ?-shaped 8-pair thermoelectric generator(Elsevier Science Bv, 2019) Kilinc, Enes; Uysal, Fatih; Celik, Erdal; Kurt, HuseyinIn this study, steady-state thermal-electric analysis of a pi-shaped 8-pair TEG was performed by finite element method using thermal-electric module in Ansys Workbench for high temperature applications. TE powders of Ca2.7Ag0.3Co4O9 and Zn0.94Al0.04In0.02O were synthesized by sol-gel method followed by cold pressing (CP) to obtain bulk samples. High temperature thermoelectric properties of the bulk samples were used for p- and n-type legs, respectively. In the model, a Delta T temperature difference of 400 degrees C was applied to obtain a high temperature power output. As a result of the thermal-electric analysis, temperature distribution and total current density along the TEG were evaluated. (C) 2019 Elsevier Ltd. All rights reserved.
