PDF Publication Title:
Text from PDF Page: 005
Energies 2020, 13, 5198 5 of 11 EEC, which represents the system under study. As known, at the high frequency region, the impedance spectrum is characterized by a point, none as the high-frequency resistance (HFR), where the plot intercepts the real impedance axis that symbolizes the ohmic resistance [17,18]. This loss is time independent, is expressed by the Ohm’s law, and is represented in the equivalent electrical circuit by a resistor, ROhm, as displayed in Figure 3. The other two regions, medium- and low-frequency regions, are characterized by an arc that represents, respectively, the activation resistance/losses, which decrease with a decrease of the fuel cell voltage, and the concentration resistance/losses, which increase with a decrease of the fuel cell voltage [17,18]. These arcs are represented in the EEC through a resistor (R) in parallel with a constant phase element (CPE), related to the capacitance properties of the double-layer interfaces (Figure 3). Nevertheless, it should be mentioned that in some systems, such as the one under study, it is not possible to identify the concentration losses, since all the resistances decrease with a decrease of the fuel cell voltage (Figure 2 and Table 1), a characteristic behavior of the activation losses. Thus, the arcs in the medium- and low-frequency regions of the impedance spectrum presented in Figure 2, are due to activation losses, where the resistance decrease with a decrease of the voltage [19,20]. After concluding that, it is mandatory to connect each activation loss with the various phenomena that occur in a pDMFC. The activation resistance/losses are directly related to the electrochemical reactions that occur in a DMFC, which in an ideal situation are the methanol oxidation reaction (MOR) at the anode side (RA) and the oxygen reduction reaction (ORR) at the cathode side (RC). However, as known, in a working DMFC, an additional electrochemical reaction occurs at the cathode side, the methanol oxidation reaction, due to the methanol that crosses the membrane from the anode to the cathode side (RCrossover). Additionally, as the methanol crossover rate decreases with a decrease of the fuel cell voltage [21], the crossover losses also decrease, as can be corroborated by the RCrossover values presented in Table 1. Table 1. EIS data estimated from the equivalent electric circuit (EEC) proposed in Figure 3; methanol concentration: 1 M. ROhm (Ω) RA (Ω) RC (Ω) RCrossover (Ω) 0.45 0.4 0.18 0.18 0.15 0.15 0.47 0.47 7.2 3.1 Voltage (V) 0.35 0.3 0.2 0.18 0.18 0.18 0.15 0.15 0.15 0.47 0.32 0.17 1.5 1.2 0.7 Based on the EIS spectrum obtained for the different voltages tested and its interpretation/analyses, the EEC that characterizes the system under study, pDMFC, is composed by a resistance in series with three parallel circuits, each one representing one arc of the Nyquist plot, composed by a resistance and a CPE (Figure 3). As presented in Figure 2, a good agreement between the EEC proposed in this work and the impedance data was achieved, showing that the EEC used reproduces with exactness the pDMFC. These results are new and groundbreaking, allowing a way to access the crossover losses through the EIS measurements. As the EIS data for all the conditions tested presented the same behavior/trends, only the EIS data for a voltage of 0.2 V (voltage near to the maximum power density obtained for each condition tested) will be shown in the next subsections. 3.2. Carbon Cloth as Anode DL Figure 4 shows the polarization curves of a pDMFC using four different carbon cloths as ADL for different methanol concentrations. The values of the resistances in the EEC, at 0.2 V and at the different methanol concentrations tested, as well as the maximum power density achieved for each configuration are shown in Table 2. The plots presented in Figure 4 put in evidence that it was only possible toPDF Image | Anode Diffusion Layer Properties on Direct Methanol Fuel Cell
PDF Search Title:
Anode Diffusion Layer Properties on Direct Methanol Fuel CellOriginal File Name Searched:
energies-13-05198.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)