Browsing by Author "Alpaydin, Guvenc Umur"

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Mathematical Modeling of a Direct Dimethyl Ether Fuel Cell
(Wiley-hindawi, 2022) Alpaydin, Guvenc Umur; Durmus, Gizem Nur Bulanik; Colpan, C. Ozgur; Devrim, Yilser
In this study, a mathematical model of a direct dimethyl ether fuel cell (DDMEFC) is developed to examine the effect of operating conditions on voltage losses and cell performance. In modeling, the electrochemical relations and mass balances are used to find the cell voltage for the given conditions. The values of some modeling parameters are determined using experimental data through curve fitting. For validation purposes, in-house experimental studies are conducted. For this purpose, Pt50Ru25Pd25/C, Pt40Ru40Pd20/C, and Pt50Pd50/C anode catalysts are synthesized by the microwave method. The effects of these synthesized catalysts and the operating conditions (cell temperature, the molar ratio of dimethyl ether, and water) on the DDMEFC performance are discussed by comparing the activation and ohmic polarization as well as the polarization curves using the model developed. This cell-level modeling approach could be considered as a preliminary step in the design process of a DDMEFC stack.
Optimization of modeling parameters of of a direct dimethyl ether fuel cell (DDMEFC)
(Ieee, 2019) Alpaydin, Guvenc Umur; Colpan, C. Ozgur; Devrim, Yilser
Direct 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.
Citation - WoS: 26
Citation - Scopus: 27
Performance of an Ht-Pemfc Having a Catalyst With Graphene and Multiwalled Carbon Nanotube Support
(Wiley, 2019) Alpaydin, Guvenc Umur; Devrim, Yilser; Colpan, C. Ozgur
In this study, the effect of multiwalled carbon nanotube and graphene nanoplatelet-based catalyst supports on the performance of reformate gas-fed polybenzimidazole (PBI)-based high-temperature proton exchange membrane fuel cell (HT-PEMFC) was investigated. In addition, the effect of several microwave conditions on the performance of the Pt-Ru/multiwalled carbon nanotube (MWCNT)-graphene nanoplatelet (GNP) catalyst was assessed. Through X-ray diffraction, thermal gravimetric analysis, transmission electron microscopy, scanning electron microscopy, and energy dispersive spectroscopy, the catalysts' chemical structure and morphology were characterized. Cyclic voltammetry analysis was used for the electrochemical characterization of catalysts through an electrochemical cell with three electrodes connected to a potentiostat. The results showed that the best performing catalyst is the catalyst produced using 800-W power for 40 seconds. The electrochemically active surface area values of this catalyst ranged from 54 to 45 m(2)/g. Single-cell performance tests of the HT-PEMFC were then carried out. In these tests, reformate gas mixture, consisting of H-2, CO2, and CO, was fed to the anode side at 160 degrees C without humidification. These tests for the best performing catalyst yielded peak power density of 0.280 W/cm(2) and current density (at 0.6 V) of 0.180 A/cm(2) in the H-2/air environment and peak power density of 0.266 W/cm(2) and current density (at 0.6 V) of 0.171 A/cm(2) in the reformate gas/air environment. As a result of the experiments, it was found that Pt-Ru/MWCNT-GNP hybrid material is a suitable catalyst for HT-PEMFC.