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Conference Object Citation - WoS: 28Citation - Scopus: 34Enhancement of Direct Methanol Fuel Cell Performance Through the Inclusion of Zirconium Phosphate(Pergamon-elsevier Science Ltd, 2017) Ozden, Adnan; Ercelik, Mustafa; Ozdemir, Yagmur; Devrim, Yilser; Colpan, C. OzgurNafion/zirconium hydrogen phosphate (ZrP) composite membranes containing 2.5 wt.% ZrP (NZ-2.5) or 5 wt.% ZrP (NZ-5) were prepared to improve the performance of a direct methanol fuel cell (DMFC). The influence of ZrP content on the Nafion matrix is assessed through characterization techniques, such as Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), and water uptake measurement. Performance testings of the DMFCs based on these composite membranes as well as commercial Nafion (R) 115 membrane were performed using a computer aided fuel cell test station for different values of cell temperature (40 degrees C, 60 degrees C, 80 degrees C, and 100 degrees C) and methanol concentration (0.75 M, 1.00 M, and 1.50 M). Characterization studies indicated that incorporation of ZrP into polymer matrix enhanced the water uptake and proton conductivity values of Nafion membrane. The results of the performance tests showed that the Membrane Electrode Assembly (MEA) having NZ-2.5 provided the highest performance with the peak power density of 551.52 W/m(2) at 100 degrees C and 1.00 M. Then, the performances of the MEAs having the same NZ-2.5 membrane but different cathode catalysts were investigated by fabricating two different MEAs using cathode catalysts made of Pt/C-ZrP and Pt/C (HiSPEC (R) 9100). According to the results of these experiments, the MEA having NZ-2.5 membrane and Pt/C (HiSPEC (R) 9100) cathode catalyst containing 10 wt.% of ZrP exhibited the highest performance with the peak power density of 620.88 W/m(2) at 100 degrees C and 1.00 M. In addition, short-term stability tests were conducted for all the MEAs. The results of the stability tests revealed that introduction of ZrP to commercial (HiSPEC (R) 9100) cathode catalyst improves its stability characteristics. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 8Experimental and Modeling Studies of a High-Temperature Electrochemical Hydrogen Compressor(Pergamon-elsevier Science Ltd, 2024) Durmus, Gizem Nur Bulanik; Kuzu, Cemil; Devrim, Yilser; Colpan, C. OzgurSome non-technical factors such as economics and logistics prevent hydrogen (H2) tech-nologies from becoming more widespread in daily life. Today, the prevalence of H2 tech-nologies requires new technological developments. Electrochemical hydrogen compressors (ECHC) are of great interest due to their ability to pressurize and purify in one step. In this study, the electrochemical H2 compression performance of high phosphoric acid (PA) doped poly 2,2-m-phenylene-5,5-benzimidazole (PBI) membrane-based HT-ECHC under high temperature and non-humid conditions was investigated through both an experimental and a numerical approach. The H2 compression capacity of HT-ECHC at different operating voltages was examined by performance tests at 160 degrees C, and it was determined that the electrochemical compression performance increased with increasing operating voltage. It was observed that the current density values also increased with increasing voltage, and it was determined that a current density of 61.2 A was obtained at 1 V. As a result of the tests, H2 was successfully compressed from atmospheric pressure to 60 bar by HT-ECHC without any gas leakage. The results of the developed model were compared with the experimental performance test data, and the variation of molar flow, cell voltage, and cell efficiency over time was examined. It has been determined that the back diffusion from the cathode to the anode in the cell increases with the increasing operating voltage of HT-ECHC and therefore the cell efficiency decreases. It has been evaluated that the developed model and experimental results are in good agreement. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 58Citation - Scopus: 62Energy 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, YilserHigh-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 - WoS: 61Citation - Scopus: 73Evaluation of Sulfonated Polysulfone/Zirconium Hydrogen Phosphate Composite Membranes for Direct Methanol Fuel Cells(Pergamon-elsevier Science Ltd, 2017) Ozden, Adnan; Ercelik, Mustafa; Devrim, Yilser; Colpan, C. Ozgur; Hamdullahpur, FeridunDirect methanol fuel cell (DMFC) technology has advanced perceivably, but technical challenges remain that must be overcome for further performance improvements. Thus, in this study, sulfonated polysulfone/zirconium hydrogen phosphate (SPSf/ZrP) composite membranes with various sulfonation degrees (20%, 35%, and 42%) and a constant concentration of ZrP (2.5%) were prepared to mitigate the technical challenges associated with the use of conventional Nafion (R) membranes in DMFCs. The composite membranes were investigated through Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), Thermogravimetric Analysis (TGA), oxidative stability and water uptake measurements, and single cell testing. Comparison was also made with Nafion (R) 115. Single cell tests were performed under various methanol concentrations and cell temperatures. Stability characteristics of the DMFCs under charging and discharging conditions were investigated via 1200 min short-term stability tests. The response characteristics of the DMFCs under dynamic conditions were determined at the start-up and shut-down stages. Composite membranes with sulfonation degrees of 35% and 42% were found to be highly promising due to their advanced characteristics with respect to proton conductivity, water uptake, thermal resistance, oxidative stability, and methanol suppression. For the whole range of parameters studied, the maximum power density obtained for SPSf/ZrP-42 (119 mW cm (2)) was found to be 13% higher than that obtained for Nafion (R) 115 (105 mW cm (2)). (C) 2017 Elsevier Ltd. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Thermoeconomic Analysis of an Integrated Membrane Reactor and Carbon Dioxide Capture System Producing Decarbonized Hydrogen(Pergamon-elsevier Science Ltd, 2025) Atak, Yagmur Nalbant; Ince, Alper Can; Colpan, C. Ozgur; Iulianelli, Adolfo; Serincan, Mustafa Fazil; Pasaogullari, UgurIn this study, a novel thermo-economic analysis on a membrane reactor adopted to generate hydrogen, coupled to a carbon-dioxide capture system, is proposed. Exergy destruction, fuel, and environmental as well as purchased equipment costs have been accounted to estimate the cost of hydrogen production in the aforementioned integrated plant. It has been found that the integration of the CO2 capture system with the membrane reactor is responsible for the reduction of the hydrogen production cost by 12 % due to the decrease in environmental penalty cost. In addition, the effects of operating parameters (steam-to-carbo ratio and biogas temperature) on the hydrogen production cost are investigated. Hence, this work demonstrates that the latter can be decreased by approximately 2 $/kgH2 when steam to carbon ratio increases from 1.5 to 4. The analyses reveal that steam-tocarbo ratio increases exergy destruction cost, affecting consequently also the hydrogen production cost. However, from a thermodynamic point of view, it enhances the hydrogen production in the membrane reactor, mutually lowering the hydrogen production cost. It has been also estimated that a decrease in the biogas inlet temperature from 450 to 400 degrees C can reduce the hydrogen production cost by 7 %. This study demonstrates that the fuel cost is a major economic parameter affecting commercialization of hydrogen production, while exergy destruction and environmental costs are also significant factors in determining the hydrogen production cost.Article Citation - WoS: 14Citation - Scopus: 14High-Temperature Electrochemical Hydrogen Separation From Reformate Gases Using Pbi/Mof Composite Membrane(Pergamon-elsevier Science Ltd, 2023) Durmus, Gizem Nur Bulanik; Eren, Enis Oguzhan; Devrim, Yilser; Colpan, C. Ozgur; Ozkan, NecatiIn this paper, the high-temperature electrochemical Hydrogen (H2) purification perfor-mance of a polybenzimidazole/UIO-66 metal-organic framework (PBI/UIO-66) membrane is investigated and analyzed at different values of current, temperature, and reformate feed composition. Purification measurements show that a significant reduction in gas impu-rities can be obtained. In the performance tests, three different ratios of reformate gas (RG) (H2:carbon dioxide (CO2):carbon monoxide (CO)) as RG-1= (75:25:0), RG-2= (75:22:3), and RG-3= (95:0:5) were used. The highest purification values were observed at 160 & DEG;C as 99.999%, 99.931%, and 99.708% for RG-1, RG-2, and RG-3, respectively. The obtained results show that an electrochemical H2 purification (ECHP) based on PBI/UIO-66 composite membrane is promising for H2 purification.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 75Citation - Scopus: 89Investigation of Nafion Based Composite Membranes on the Performance of Dmfcs(Pergamon-elsevier Science Ltd, 2017) Ercelik, Mustafa; Ozden, Adnan; Devrim, Yilser; Colpan, C. OzgurIn 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.Conference Object Citation - WoS: 34Citation - Scopus: 39Development of a One-Dimensional and Semi-Empirical Model for a High Temperature Proton Exchange Membrane Fuel Cell(Pergamon-elsevier Science Ltd, 2018) Nalbant, Yagmur; Colpan, C. Ozgur; Devrim, YilserHigh temperature proton exchange membrane fuel cells (HT-PEMFC), which operate between 160 degrees C and 200 degrees C, can be generally used in portable and stationary power generation applications. In this study, a one-dimensional, semi-empirical, and steady-state model of a HT-PEMFC fed with a gas mixture consisting of hydrogen and carbon monoxide is developed. Some modeling parameters are adjusted using empirical data, which are obtained conducting experiments on a HT-PEMFC for different values of Pt loading and cell temperature. For adjusting these parameters, the total summation of the square of the difference between the cell voltages found using the experimental and theoretical methods is minimized using genetic algorithm. After finding the values of the adjusted parameters, the effects of different cell temperature, Pt loading, phosphoric acid (PA) percentage, and different binders (PBI and PVDF) on the performance of the fuel cell are examined. It was found that, the performance of the fuel cell using PVDF binder exhibited better performance as compared to that using PBI binder. (c) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
