Browsing by Author "Doğan H."

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    The effect of ambient temperature on electric power generation in natural gas combined cycle power plant—A case study
    (Elsevier Ltd, 2018) Şen G.; Nil M.; Mamur H.; Doğan H.; Karamolla M.; Karaçor M.; Kuyucuoğlu F.; Yörükeren N.; Bhuiyan M.R.A.
    Natural gas combined cycle power plants (CCPPs) are widely used to meet peak loads in electric energy production. Continuous monitoring of the output electrical power of CCPPs is a requirement for power performance. In this study, the role of ambient temperature change having the greatest effect on electric production is experimentally investigated for a natural gas CCPP. The plant has generated electricity for fourteen years and setup at 240 MW in Aliağa, İzmir, Turkey. Depending on the seasonal temperature changes, the study data were obtained from each gas turbine (GT), steam turbine (ST) and combined cycle blocks (CCBs) in the ambient temperature range of 8–23 °C. In electric energy production, an important decrease was in the GTs because of the temperature increase. This decrease indirectly affected the electric energy production of the STs. As a result, the efficiency of each GT, ST and CCB decreased, although the quantity of fuel consumed by the controllers in the plant was reduced. As a result of this data, it has been recommended and applied that additional precautions have been taken in the power plant to bring the air entering the combustion chamber to ideal conditions and necessary air cooling systems have been installed. © 2018 The Authors
  • No Thumbnail Available
    Item
    Life performance prediction of natural gas combined cycle power plant with intelligent algorithms
    (Elsevier Ltd, 2021) Karaçor M.; Uysal A.; Mamur H.; Şen G.; Nil M.; Bilgin M.Z.; Doğan H.; Şahin C.
    The efficient use of a system is enabled with the life performance estimations. Thus, the effective use of underground resources is realized especially natural gas. Based on this, life performance models were generated to aim of improving the efficient use of energy for a combined cycle power plant (CCPP) of 243 MW installed in Izmir, Turkey by using fuzzy logic (FL) and artificial neural network (ANN) in this study. Therefore, output power estimations were carried out. Depending on the developed models, an estimation of the energy that the CCPP can produce and provide to the interconnected system in the following years has been made. According to the obtained results, the error prediction rates of FL and ANN models were determined. It was found that while the energy relative error estimation value that can be produced between the years calculated in modeling using FL varies between 0.59% and 3.54%, this value was found to vary between 0.001% and 0.84% in modeling using ANN. This result shows that the ANN model is more suitable for the life performance estimations of such a non-linear system. © 2021 Elsevier Ltd
  • No Thumbnail Available
    Item
    The Experimental Assessment of Deformation and Springback Behavior for Additive Manufactured Ti6Al4V
    (Institute for Ionics, 2023) Aydın K.; Karamolla M.; Karaağaç İ.; Kabakçı M.O.; Doğan H.
    In this study, heat treatment was applied to Ti6Al4V materials produced by the selective laser melting (SLM) method at 550 ℃, 800 ℃, 950 ℃, and 1080 ℃ temperatures, and the effect of this process on microstructure and mechanical properties was also investigated. Moreover, the parts produced with the additive manufacturing technique can be exposed to many loads at the place of use. Therefore, to determine the resistance of the materials against bending, the V bending process was applied to the materials in 6-, 7.5-, and 9-degree dies. XRD and SEM investigated the microstructure and optical microscope changes, and the mechanical properties were examined by uniaxial tensile test and microhardness analysis. In the test samples, pore and unmelted powder particles due to production in the microstructure were observed, and it was observed that the grain sizes increased with the increase in the heat treatment temperature. It was observed that samples HT550, HT800, and HT950 were shaped without breaking in the bending process in the 6-degree die, and all the samples were broken in the experiments performed in the 7.5- and 9-degree die. © 2023, King Fahd University of Petroleum & Minerals.
  • No Thumbnail Available
    Item
    The effect of heat treatment on laser-welding performance of additive manufactured Ti6Al4V sheets
    (Springer Science and Business Media Deutschland GmbH, 2023) Aydin K.; Karamolla M.; Karaağaç İ.; Kaçal A.; Doğan H.
    In this study, the laser weldability of Ti6Al4V materials produced by the selective laser melting (SLM) method, which is an additive manufacturing method, and the effects of heat treatment applied to the welded material on the welding performance were investigated experimentally. Stress relief and heat treatment were applied to the materials joined by laser welding at 800 °C (below the α phase transformation temperature), 950 °C (between α and β phase transformation temperature), and 1080 °C (above the β phase transformation temperature). In addition, transverse and longitudinal welded joining techniques were also investigated to determine anisotropy in the produced parts. The mechanical properties in the laser-welded region were examined by hardness and tensile tests, and an optical microscope, scanning electron microscope (SEM), and X-ray diffraction (XRD) examined the changes in the microstructure. Grain growth was observed in the microstructure due to the increase in heat treatment temperature, and the tensile strength increased from 631.2 to 754.2 MPa in transverse bonding, while it increased from 648.1 to 761.9 MPa in longitudinal bonding. High hardness values due to Widmanstatten morphology were determined in the hardness test, especially after heat treatments at 950 and 1080 °C. It has been observed that the heat treatment increases the welding performance of the laser-welded material, and the best welding performance is obtained with a welding efficiency of 83.5% in the heat treatment at 1080 °C. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.
  • No Thumbnail Available
    Item
    Deposition of HA-GO on ASO modified Ti surface by EPD method and characterization of surface and biological properties of the coating
    (Elsevier Ltd, 2025) Kırman M.; Doğan H.; Dikici T.
    In this study, the surfaces of titanium (grade 2) substrates were modified by different methods and then coated with a hydroxyapatite-graphene oxide (HA-GO) composite by electrophoretic deposition (EPD). The aim of the study is to improve the surface properties and increase the hydrophilicity of the surface of titanium by different surface treatments. The surface modification processes are as follows: sandblasting (S), acid etching (E), and finally anodic spark oxidation (ASO) on the etched surface. After the surface modification processes, the surface of titanium was coated with HA-GO suspensions (0, 2, 4, and 6 wt% GO) with a voltage value of 20 for 5 min by the EPD method. The surface morphology, elemental analysis, contact angle, phase composition, adhesion, biocompatibility, and bioactivity of the produced coatings were examined. Bioactivity analysis was performed in simulated body fluid (SBF) for 14 days. The MTT experiment was conducted with L929 (mouse fibroblast) cell cultures in accordance with the 70 % cell viability criterion. As a result of contact angle measurements, it was observed that all samples showed hydrophilic behavior due to the increased surface area after ASO treatment. The contact angle of the sanded surface was 71.03°, whereas the contact angles of the ASO treatment and HA-GO coatings after the coating process were measured below 5°. The bioactivity test results indicated that the surface modified with HA-GO (4 wt%) exhibited the best apatite nucleation outcome. As a result of the analysis with L929 cells, HA, HA-GO (2 wt%), HA-GO (4 wt%) composite coatings showed biocompatible behaviour with 102.17, 76.52, and 80.43 % cell viability, respectively. The best result in the adhesion test was reported for HA-GO (4 wt%) coating with class 5B. © 2024 Elsevier Ltd and Techna Group S.r.l.