Devrim, Yılser
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D.,Yılser
Yilser, Devrim
Y.,Devrim
Devrim Y.
Devrim, Yılser
Güldogan, Y
Devrim, Yilser G.
D., Yilser
Yılser, Devrim
Devrim, YG
Devrim,Y.
Devrim, Yiser
D., Yılser
Devrim, Y. G.
D.,Yilser
Y., Devrim
Devrim, Yilser
Yilser, Devrim
Y.,Devrim
Devrim Y.
Devrim, Yılser
Güldogan, Y
Devrim, Yilser G.
D., Yilser
Yılser, Devrim
Devrim, YG
Devrim,Y.
Devrim, Yiser
D., Yılser
Devrim, Y. G.
D.,Yilser
Y., Devrim
Devrim, Yilser
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Profesor Doktor
Email Address
yilser.devrim@atilim.edu.tr
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Scholarly Output
85
Articles
53
Citation Count
2249
Supervised Theses
9
84 results
Scholarly Output Search Results
Now showing 1 - 10 of 84
Article Citation Count: 21Reliability based modeling of hybrid solar/wind power system for long term performance assessment(Elsevier Sci Ltd, 2021) Eryilmaz, Serkan; Bulanik, Irem; Devrim, Yilser; Industrial Engineering; Energy Systems EngineeringThis paper is concerned with reliability based long-term performance assessment of hybrid solar/wind power system. In particular, an analytical expression is obtained for the theoretical distribution of the power output of the hybrid system by taking into account the reliability values of renewable energy components. An expression for the expected energy not supplied (EENS) is also derived and used to compute the energy index of reliability (EIR) that is directly related to EENS. Because the derived expressions involve reliability values which are related to mechanical states of the renewable energy components, the results enable us to evaluate properly the performance of the hybrid system. A numerical example is included to illustrate the results.Conference Object Citation Count: 47Energy and exergy performance assessments of a high temperature-proton exchange membrane fuel cell based integrated cogeneration system(Pergamon-elsevier Science Ltd, 2020) Nalbant, Yagmur; Colpan, C. Ozgur; Devrim, Yilser; Energy Systems EngineeringHigh-temperature proton exchange membrane fuel cell (HT-PEMFC), which operates between 160 degrees C and 200 degrees C, is considered to be a promising technology, especially for cogeneration applications. In this study, a mathematical model of a natural gas fed integrated energy system based on HT-PEMFC is first developed using the principles of electrochemistry and thermodynamics (including energy and exergy analyses). The effects of some key operating parameters (e.g., steam-to-carbon ratio, HT-PEMFC operating temperature, and anode stoichiometric ratio) on the system performance (electrical, cogeneration, and exergetic efficiencies) are examined. The exergy destruction rates of each component in the integrated system are found for different values of these parameters. The results show that the most influential parameter which affects the performance of the integrated system is the anode stoichiometric ratio. For the baseline conditions, when the anode stoichiometric ratio increases from 1.2 to 2, the electrical, cogeneration, and exergetic efficiencies decrease by 42.04%, 33.15%, and 37.39%, respectively. The highest electrical power output of the system is obtained when the SCR, operating temperature, and anode stoichiometric ratio are taken as 2, 160 degrees C, and 1.2, respectively. For this case, the electrical, cogeneration, and exergetic efficiencies are found as 26.20%, 70.34%, and 26.74%, respectively. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation Count: 21Preparation of polybenzimidazole/ZIF-8 and polybenzimidazole/UiO-66 composite membranes with enhanced proton conductivity(Pergamon-elsevier Science Ltd, 2022) Eren, Enis Oguzhan; Ozkan, Necati; Devrim, Yilser; Energy Systems EngineeringMetal-organic frameworks (MOFs) are considered emerging materials as they further improve the various properties of polymer membranes used in energy applications, ranging from electrochemical storage and purification of hydrogen to proton exchange membrane fuel cells. Herein, we fabricate composite membranes consisting of polybenzimidazole (PBI) polymer as a matrix and MOFs as filler. Synthesis of ZIF-8 and UiO-66 MOFs are conducted through a typical solvothermal method, and composite membranes are fabricated with different MOF compositions (e.g., 2.5, 5.0, 7.5, and 10.0 wt %). We report a significant improvement in proton conductivity compared with the pristine PBI; for example, more than a three-fold increase in conductivity is observed when the PBI-UiO66 (10.0 wt %) and PBI-ZIF8 (10.0 wt %) membranes are tested at 160 degrees C. Proton conductivities of the composite membranes vary between 0.225 and 0.316 S cm(-1) at 140 and 160 degrees C. For the comparison, pure PBI exhibits 0.060 S cm(-1) at 140 degrees C and 0.083 S cm(-1) at 160 degrees C. However, we also report a decrease in permeability and mechanical stability with the composite membranes. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Conference Object Citation Count: 0Optimization of modeling parameters of of a direct dimethyl ether fuel cell (DDMEFC)(Institute of Electrical and Electronics Engineers Inc., 2019) Alpaydin,G.U.; Ozgur Colpan,C.; Devrim,Y.; Energy Systems EngineeringDirect alcohol fuel cells are one of the suitable candidates for sustainable power generation in portable applications. Among the different alcohol types that can be used in these fuel cells, DME, which is almost non-Toxic at room temperature and easy to liquefy, and has a molecular structure similar to methanol, is one of the suitable options. For this reason, many studies have been carried out to develop direct dimethyl ether fuel cell (DDMEFC). Mathematical modeling studies also play an important role in the development of DDMEFC since they enable the understanding of the performance of the fuel cells more thoroughly. In this study, a model has been developed by using the principles of conservation chemical species and electrochemistry. A modeling study was performed using MATLAB. The values of some modeling parameters were estimated using the genetic algorithm optimization technique. © 2019 University of Split, FESB.Article Citation Count: 65Investigation of Nafion based composite membranes on the performance of DMFCs(Pergamon-elsevier Science Ltd, 2017) Ercelik, Mustafa; Ozden, Adnan; Devrim, Yilser; Colpan, C. Ozgur; Energy Systems EngineeringIn this study, Direct Methanol Fuel Cells (DMFCs) based on composite membranes (Nafion/ SiO2 and Nafion/TiO2) were manufactured; and their performances were compared with that of the DMFC based on Nafion (R) 115 membrane. For this purpose, composite membranes were synthesized applying the recasting method with the inorganic particle loading of 2.5 wt%. The structures of these composite membranes were investigated by Scanning Electron Microscopy (SEM), proton conductivity measurement and water uptake measurement. Ultrasonic coating technique was used in the manufacturing of the Membrane Electrode Assemblies (MEAs). The performance tests of the composite membranes were conducted using in-house experiments. In these tests, the effect of methanol concentration (0.75, 1, and 1.5 M) on the performance of the MEA having Nafion 115 was investigated at 80 degrees C to find the value of the methanol concentration that yields the highest power density. This study showed that the MEA operating at 1 M gives the highest performance. Then, the performance of this MEA was compared with that of the MEAs having Nafion/ SiO2 and Nafion/TiO2 composite membranes in single cell DMFC setup at 60 degrees C, 80 degrees C, and 95 degrees C. The results of these experiments demonstrated that the MEA having Nafion/TiO2 composite membrane provides much better performance with the maximum power density values of 422.04 W/m(2), 641.16 W/m(2), and 710.88 W/m(2) at 60 degrees C, 80 degrees C, and 95 degrees C, respectively. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation Count: 153Development of polybenzimidazole/graphene oxide composite membranes for high temperature PEM fuel cells(Pergamon-elsevier Science Ltd, 2017) Uregen, Nurhan; Pehlivanoglu, Kubra; Ozdemir, Yagmur; Devrim, Yilser; Energy Systems EngineeringIn this study, phosphoric acid doped Polybenzimidazole/Graphene Oxide (PBI/GO) nano composite membranes were prepared by dispersion of various amounts of GO in PBI polymer matrix followed by phosphoric acid doping for high temperature proton exchange membrane fuel cell (HT-PEMFC) application. The structure of the PBI/GO composite membranes was investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and by thermogravimetric analysis (TGA). The introduction of GO into the FBI polymer matrix helps to improve the acid doping, proton conductivity and acid leaching properties. The SEM analyses have proved the uniform and homogeneous distribution of GO in composite membranes. The composite membranes were tested in a single HT-PEMFC with a 5 cm(2) active area at 165 degrees C without humidification. HT-PEMFC tests show that PBI/ GO composite membrane with 2 wt. % GO content performed better than bare PBI membrane at non humidified condition. At ambient pressure and 165 degrees C, the maximum power density of the PBI/GO-1 membrane can reach 0.38 W/cm(2), and the current density at 0.6 V is up to 0.252 A/cm(2), with H-2/air. The results indicate the PBI/GO composite membranes could be utilized as the proton exchange membranes for HT-PEMFC. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation Count: 15PEM fuel cell short stack performances of silica doped nanocomposite membranes(Pergamon-elsevier Science Ltd, 2015) Devrim, Yilser; Devrim, Huseyin; Energy Systems EngineeringIn this study, an air-cooled Proton Exchange Membrane Fuel Cell (PEMFC) short stack with Nafion/Silica nanocomposite membrane was designed and fabricated for net 100 W net power output to improve the stack performance at low relative humidity conditions. Composite membrane was prepared by solution casting method. Gas Diffusion Electrodes (GDE's) were produced by ultrasonic spray coating technique. Short stack design was based on electrochemical data obtained at 0.60 V was 0.45 A/cm(2) from performance tests of a single cell having the same membrane electrode assemblies (MEA) that had an active area of 100 cm(2). The short stack was tested in the constant resistance load regime, in dead-end rode, with controlling temperature by air on-off control system. A maximum power of 117 W was obtained from the short stack. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Conference Object Citation Count: 79Modeling and sensitivity analysis of high temperature PEM fuel cells by using Comsol Multiphysics(Pergamon-elsevier Science Ltd, 2016) Sezgin, Berna; Caglayan, Dilara Gulcin; Devrim, Yilser; Steenberg, Thomas; Eroglu, Inci; Energy Systems EngineeringThe objective of this study is to observe the effect of the critical design parameters, velocities of inlet gases (hydrogen and air) and the conductivity of polymer membrane, on the performance of a high temperature PEM fuel cell. A consistent and systematic mathematical model is developed in order to study the effect of these parameters. The model is applied to an isothermal, steady state, three-dimensional PEM fuel cell in order to observe concentration profiles, current density profiles and polarization curves. The model includes the transport of gases in anode and cathode gas flow channels, diffusion in the catalyst layers, the transport of water and hydronium ion in the polymer electrolyte and in the catalyst layers, and the transport of electrical current in the solid phase. The model is considered as having a single flow channel. The simulation is performed by using licensed Comsol Multiphysics 5.0, Fuel Cells &Batteries Module. The results compare well with the experimental polarization data obtained at 160 degrees C for ohmic and activation regions. The best match with the experimental data is obtained when the inlet hydrogen gas velocity is 0.133 m/s whereas inlet air velocity is 1.3 m/s for proton conductivity of 10 S/m. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation Count: 2Development and performance analysis of polybenzimidazole/boron nitride composite membranes for high-temperature PEM fuel cells(Wiley, 2022) Hussin, Dedar Emad; Budak, Yagmur; Devrim, Yilser; Energy Systems EngineeringIn this research, polybenzimidazole/boron nitride (PBI/BN) based composite membranes have been prepared for high-temperature PEM fuel cell (HT-PEMFC). BN was preferred because of its superior thermal robustness, high chemical stability, non-conductor property, and high plasticizer characteristic. The loading of BN in the composite membrane was studied between 2.5 to 10 wt%. The composite membranes were characterized using TGA, DSC, XRD, SEM, mechanical tests, acid doping/leaching, and proton conductivity measurements. The highest conductivity of 0.260 S/cm was found for PBI/BN-2.5 membrane at 180 degrees C. It has been determined that the PBI/BN-2.5 membrane has higher performance than the PBI membrane according to the HT-PEMFC tests performed with Hydrogen and dry air. The heightened HT-PEMFC performance can be ascribed to interactive effects between BN particles and the PBI polymer matrix. PBI/BN composite membranes show a good perspective in the high-temperature PEMFC applications.Article Citation Count: 10On the theoretical distribution of the wind farm power when there is a correlation between wind speed and wind turbine availability(Elsevier Sci Ltd, 2020) Kan, Cihangir; Devrim, Yilser; Eryilmaz, Serkan; Industrial Engineering; Energy Systems EngineeringIt is important to elicit information about the potential power output of a wind turbine and a wind farm consisting of specified number of wind turbines before installation of the turbines. Such information can be used to estimate the potential power output of the wind farm which will be built in a specific region. The output power of a wind turbine is affected by two factors: wind speed and turbine availability. As shown in the literature, the correlation between wind speed and wind turbine availability has an impact on the output of a wind farm. Thus, the probability distribution of the power produced by the farm depending on the wind speed distribution and turbine availability can be effectively used for planning and risk management. In this paper, the theoretical distribution of the wind farm power is derived by considering the dependence between turbine availability and the wind speed. The theoretical results are illustrated for real wind turbine reliability and wind speed data.
