Browsing by Author "Budak, Yagmur"
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Article Citation Count: 24Carbon nanotube-graphene supported bimetallic electrocatalyst for direct borohydride hydrogen peroxide fuel cells(Pergamon-elsevier Science Ltd, 2021) Devrim, Yılser; Akca, Elif Seda; Uzundurukan, Arife; Devrim, Yilser; Energy Systems EngineeringAt present study, carbon nanotube-graphene (CNT-G) supported PtAu, Au and Pt catalysts were prepared by microwave-assisted synthesis method to investigate the direct liquid-fed sodium borohydride/hydrogen peroxide (NaBH4/H2O2) fuel cell performance. Prepared catalysts were characterized by TGA, XRD, TEM, ICP-OES, cyclic voltammetry and rotating disc electrode (RDE) voltammetry. The catalysts were tested in a single NaBH4/H2O2 fuel cell with 25 cm(2) active area to evaluate fuel cell performance. The effects of temperature and fuel concentration on fuel cell performance were examined to observed best operating conditions. As a result of direct NaBH4/H2O2 fuel cell experiments, maximum power densities of 139 mW/cm(2), 125 mW/cm(2) and 113 mW/cm(2) were obtained for PtAu/CNT-G, Au/CNT-G and Pt/CNT-G catalysts, respectively. PtAu/CNT-G catalyst showed the enhanced NaBH4/H2O2 fuel cell performance, which was higher than the Pt/CNT-G catalyst and Au/CNT-G catalyst at 50 degrees C. The enhanced NaBH4/H2O2 performance can be attributed to synergistic effects between Pt and Au particles on CNT-G support providing a better catalyst utilization and interaction. These results suggest that the prepared PtAu/CNT-G catalyst is a promising anode catalyst for NaBH4/H2O2 fuel cell application. (c) 2020 Elsevier Ltd. All rights reserved.Article Citation Count: 35Comparative study of PV/PEM fuel cell hybrid energy system based on methanol and water electrolysis(Pergamon-elsevier Science Ltd, 2019) Devrim, Yılser; Devrim, Yilser; Energy Systems EngineeringIn this study, we investigated the comparative analysis of a solar-fuel cell hybrid system based on water and methanol electrolysis. The proposed system comprises PV, electrolyzer and proton exchange membrane fuel cell (PEMFC). The hybrid system is designed to supply the hydrogen (H-2) needed of the PEMFC system and also to fulfill the H-2 requirement of other applications. The actual data of solar irradiation of Izmir, Turkey are used in the simulation. The methanol and water electrolyzers were designed for 1.2 kW PEMFC H-2 demand which were met a house-hold energy requirement. Analyzes show that the use of the methanol electrolyzer can produce 27% more H-2 than the water electrolyzer. According to the study, it was determined that the methanol-based hybrid system offered a viable option for self-sustaining in household application.Article Citation Count: 2Development and performance analysis of polybenzimidazole/boron nitride composite membranes for high-temperature PEM fuel cells(Wiley, 2022) Devrim, Yılser; 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: 10Evaluation of hybridsolar-wind-hydrogenenergy system based on methanol electrolyzer(Wiley, 2020) Devrim, Yılser; Devrim, Yilser; Energy Systems EngineeringIn this study, it is aimed to meet the annual electricity and heating needs of a house without interruption with the photovoltaic panel, wind turbine, methanol electrolyzer, and high temperature proton exchange membrane fuel cell system. The system results show that the use of the 2 WT with 18 PV was enough to provide the need of the methanol electrolyzer, which provides requirements of the high temperature proton exchange membrane fuel cell. The produced heat by the fuel cell was used to meet the heat requirement of the house with combined heat and power system. Electrical, thermal and total efficiencies of fuel cell system with combined heat and power were obtained as 38.54%, 51.77% and 90%, respectively. Additionally, the levelized cost of energy of the system was calculated as 0.295 $/kWh with combined heat and power application. The results of this study show that H(2)is useful for long-term energy storage in off-grid energy systems and that the proposed hybrid system may be the basis for future H-2-based alternative energy applications.Article Citation Count: 10Investigation of hydrogen production from sodium borohydride by carbon nano tube-graphene supported PdRu bimetallic catalyst for PEM fuel cell application(Wiley, 2022) Devrim, Yılser; Devrim, Yilser; Uzundurukan, Arife; Budak, Yagmur; Energy Systems EngineeringIn this study, hydrogen (H-2) generation from the hydrolysis of sodium borohydride (NaBH4) catalyzed by bimetallic Palladium-Ruthenium (PdRu) supported on multiwalled carbon nanotube-graphene (MWCNT-GNP) hybrid material is investigated. The effect of various parameters such as temperature, NaBH4 concentration, and catalyst loading and effect of base concentration are examined to observed optimum operating conditions. Experimental results show that the PdRu/MWCNT-GNP bimetallic catalyst has high catalytic activity on NaBH4 hydrolysis reaction. It has been found that PdRu/MWCNT-GNP catalyst shows low activation energy of 22.33 kJ/mol for hydrolysis reaction of NaBH4. The PdRu/MWCNT-GNP catalyst also exhibits H-2 generation rate of 79.2 mmol/min center dot g(cat) at 45 degrees C. It shows good cycle stability in the catalyst reusability test and retained 89% of its initial catalytic activity after fifth use. The high catalytic activity of the PdRu/MWCNT-GNP catalyst makes it promising in H-2 generation from NaBH4 hydrolysis for commercial proton exchange membrane fuel cell (PEMFC) applications.Article Citation Count: 71Investigation of micro-combined heat and power application of PEM fuel cell systems(Pergamon-elsevier Science Ltd, 2018) Devrim, Yılser; Devrim, Yilser; Energy Systems EngineeringThis study focuses on the investigating different working temperature effect on Proton Exchange Membrane Fuel Cell (PEMFC) stack performance, micro-combined heat and power (mu CHP) application and their simple payback time. LT-PEMFC and HT-PEMFC short stacks were designed and analyzed for 480 W net power output. Liquid cooling method was choosing for the cooling the PEMFC stacks due for efficient mu CHP applications. The experimental studies were carried out by using 13 cells HT-PEMFC and 6 cells LT-PEMFC short stacks and design parameters were determined. 1.2 kW PEMFCs with mu CHP systems with different working temperature were designed based on electrochemical data obtained from short stack testing. The proposed PEMFC systems can supply electric and hot water. The highest mu CHP system efficiency was calculated with a value of 92% for HT-PEMFC based system. The corresponding electrical and thermal efficiencies are 48% and 44%, respectively. In this study, two important parameters have been analyzing: efficiency and simple payback time. By using mu CHP application, both natural gas and H-2 based PEMFC systems SPT values are reduced.Article Citation Count: 16Micro-cogeneration application of a high-temperature PEM fuel cell stack operated with polybenzimidazole based membranes(Pergamon-elsevier Science Ltd, 2020) Devrim, Yılser; Devrim, Yilser; Energy Systems EngineeringHigh temperature Proton Exchange Membrane Fuel Cells (HT-PEMFC) have attracted the attention of researchers in recent years due to their advantages such as working with reformed gases, easy heat management and compatibility with micro-cogeneration systems. In this study, it is aimed to designed, manufactured and tested of the HT-PEMFC stack based on Polybenzimidazole/Graphene Oxide (PBI/GO) composite membranes. The micro-cogeneration application of the PBI/GO composite membrane based stack was investigated using a reformat gas mixture containing Hydrogen/Carbon Dioxide/Carbon Monoxide (H-2/CO2/CO). The prepared HT-PEMFC stack comprises 12 cells with 150 cm(2) active cell area. Thermo-oil based liquid cooling was used in the HT-PEMFC stack and cooling plates were used to prevent coolant leakage between the cells. As a result of HTPEMFC performance studies, maximum 546 W and 468 W power were obtained from PBI/ GO and PBI membranes based HT-PEMFC stacks respectively. The results demonstrate that introducing GO into the PBI membranes enhances the performance of HT-PEMFC technology and demonstrated the potential of the HT-PEMFC stack for use in micro cogeneration applications. It is also underlined that the developed PBI/GO composite membranes have the potential as an alternative to commercially available PBI membranes in the future. (c) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.