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Full-Text Articles in Engineering
Analysis Of Molten Carbonate Fuel Cell Performance Using A Three-Phase Homogeneous Model, N. Subramanian, B. S. Haran, P. Ganesan, Ralph E. White, Branko N. Popov
Analysis Of Molten Carbonate Fuel Cell Performance Using A Three-Phase Homogeneous Model, N. Subramanian, B. S. Haran, P. Ganesan, Ralph E. White, Branko N. Popov
Faculty Publications
In this study a three-phase homogeneous model was developed to simulate the performance of the molten carbonate fuel cell (MCFC) cathode. The homogeneous model is based on volume averaging of different variables in the three phases over a small volume element. This approach can be used to model porous electrodes as it represents the real system much better than the conventional agglomerate model. Using the homogeneous model the polarization characteristics of the MCFC cathode was studied under different operating conditions.
Synthesis And Characterization Of Mno2-Based Mixed Oxides As Supercapacitors, Hansung Kim, Branko N. Popov
Synthesis And Characterization Of Mno2-Based Mixed Oxides As Supercapacitors, Hansung Kim, Branko N. Popov
Faculty Publications
Mn/Pb and Mn/Ni mixed oxide were prepared at ambient temperature by reduction of KMnO4 with Mn, Pb, and Ni salts. This low-temperature approach provides amorphous structure of the active material. The specific capacitance of pure MnO2 was estimated to be 166 F/g and increased to 210 and 185 F/g for Mn/Ni and Mn/Pb oxides, respectively. The carbon loading was optimized at 20 wt %. Based on a single electrode, the Mn/Ni mixed oxide showed a high rate capability of 3.12 Wh/kg at constant power discharge of 1 kW/kg.
Development Of A Novel Electrochemical Method To Deposit High Corrosion Resistant Silicate Layers On Metal Substrates, Basker Veeraraghavan, Bala Haran, Dragan Slavkov, Swaminatha Prabhu, Branko N. Popov, Bob Heimann
Development Of A Novel Electrochemical Method To Deposit High Corrosion Resistant Silicate Layers On Metal Substrates, Basker Veeraraghavan, Bala Haran, Dragan Slavkov, Swaminatha Prabhu, Branko N. Popov, Bob Heimann
Faculty Publications
A novel method for electrodepositing silicates on metallic substrates from aqueous solutions has been developed. The technique is demonstrated by forming a passive film on galvanized steel. The silicate layer was deposited cathodically from a bath containing PQ Corporation N sodium silicate solution (3.22 weight ratio sodium silicate, 37.5% solution in water). A post-treatment drying process increased the Si content in the coating and improved the corrosion characteristics of the silicate layer. Deposition parameters like bath concentration and temperature have been optimized using corrosion characteristics and surface morphology of the final coating. Finally, stability studies show that the silicate coatings …
Polyetheretherketone Membranes For Elevated Temperature Pemfcs, Balasubramanian Lakshmanan, Wayne Huang, David Olmeijer, John W. Weidner
Polyetheretherketone Membranes For Elevated Temperature Pemfcs, Balasubramanian Lakshmanan, Wayne Huang, David Olmeijer, John W. Weidner
Faculty Publications
Membrane electrode assemblies ~MEAs! made from polyetheretherketone ~PEEK! showed excellent fuel cell performance and thermal stability in the presence of substantial CO at elevated temperatures ~i.e., 120°C! in proton exchange membrane fuel cells ~PEMFCs!. For example, the current from a MEA made from PEEK membrane at 0.6 V and 120°C was 0.50 A/cm2 when run on pure hydrogen and 0.45 A/cm2 when run on reformate ~50% H2 , 1300 ppm CO, and balance N2). The current density from a MEA made from Nafion at 0.6 V and 120°C was 0.61 A/cm2 when run on pure hydrogen. The main difference between …
Theoretical Analysis For Obtaining Physical Properties Of Composite Electrodes, Parthasarathy M. Gomadam, John W. Weidner, Thomas A. Zawodzinski, Andrew P. Saab
Theoretical Analysis For Obtaining Physical Properties Of Composite Electrodes, Parthasarathy M. Gomadam, John W. Weidner, Thomas A. Zawodzinski, Andrew P. Saab
Faculty Publications
A theoretical analysis is presented that allows in situ measurements of the physical properties of a composite electrode, namely, the electronic conductivity, the ionic conductivity, the exchange-current density, and the double-layer capacitance. Use is made of the current-voltage responses of the composite electrode to dc and ac polarizations under three different experimental configurations. This analysis allows the physical properties to be obtained even when the various resistances in the composite (e.g., ionic, electronic, and charge-transfer) are of comparable values.
Modeling Heat Conduction In Spiral Geometries, Parthasarathy M. Gomadam, Ralph E. White, John W. Weidner
Modeling Heat Conduction In Spiral Geometries, Parthasarathy M. Gomadam, Ralph E. White, John W. Weidner
Faculty Publications
A two-dimensional (2-D) energy balance (the 2D model) is reduced to a one-dimensioanl (1-D) energy balance (the 1D-radial-spiral model) by a coordinate transformation approach. The 1D-radial-spiral model, even though 1-D, captures both radial and spiral heat conductions over a wide range of design parameters. By comparing the temperature predictions of the 1D-radial-spiral model and the 2D model, parameter ranges were identified where spiral conduction was important and where the 1D-radial-spiral model held. The 1D-radial-spiral model provided a sixtyfold savings in computation time over the 2D model. When coupled to electrochemistry, the 2D model took approximately 20 h to simulate a …
A Novel Electrodeposition Process For Plating Zn-Ni-Cd Alloys, Hansung Kim, Branko N. Popov, Ken S. Chen
A Novel Electrodeposition Process For Plating Zn-Ni-Cd Alloys, Hansung Kim, Branko N. Popov, Ken S. Chen
Faculty Publications
Zn-Ni-Cd alloy was electrodeposited from an alkaline electrolytic bath under potentiostatic conditions. Bath analyses using a pH concentration diagram reveal that addition of a complexing agent is essential to maintain the bath stability. Introduction of a low concentration of CdSO4 reduces the anomalous nature of the Zn-Ni deposit. Deposits obtained from the electrolytic bath which contains 60 g/L of ZnSO4·7H2O, 40 g/L of NiSO4·6H2O, 1 g/L of CdSO4, and 80 g/L of (NH4)2SO4 in the presence of additives and ammonium hydroxide at pH 9.3 …
Corrosion Protection Of Steel Using Nonanomalous Ni-Zn-P Coatings, Basker Veeraraghavan, Bala Haran, Swaminatha P. Kumaraguru, Branko N. Popov
Corrosion Protection Of Steel Using Nonanomalous Ni-Zn-P Coatings, Basker Veeraraghavan, Bala Haran, Swaminatha P. Kumaraguru, Branko N. Popov
Faculty Publications
A novel technique for obtaining nonanomalous Ni-Zn-P coatings with high Ni content (74 wt % as compared to 15-20 wt % in the conventional plating method) has been developed. These coatings show promise as a replacement for Cd in sacrificially protecting steel. Ni-Zn-P coatings were deposited using an electroless method from a solution containing NiSO4, complexing agent and ammonium chloride. Varying the concentration of ZnSO4 in the bath controls the final amount of Zn in the deposit. The Zn content in the coating was optimized based on the corrosion resistance of the final deposit. Coatings with 16.2 …
A Mathematical Model Of Oxide/Carbon Composite Electrode For Supercapacitors, Hansung Kim, Branko N. Popov
A Mathematical Model Of Oxide/Carbon Composite Electrode For Supercapacitors, Hansung Kim, Branko N. Popov
Faculty Publications
A pseudo two-dimensional model is developed for the general application of supercapacitors consisting of an oxide/carbon composite electrode. The model takes into account the diffusion of protons in the oxide particle by employing the method of superposition. RuO2/carbon system is modeled as a specific example. From the simulation data, it is found that the oxide particle size and proton diffusion coefficient have an enormous effect on the performance at high discharge rate due to the limitation of proton transport into RuO2 particles. With increasing carbon ratio, the porosity of electrode increases, which causes the potential drop in …
Full Cell Mathematical Model Of A Mcfc, N. Subramanian, B. S. Haran, Ralph E. White, Branko N. Popov
Full Cell Mathematical Model Of A Mcfc, N. Subramanian, B. S. Haran, Ralph E. White, Branko N. Popov
Faculty Publications
A theoretical model for the molten carbonate fuel cell was developed based on the three-phase homogeneous approach. Using this model, the contribution of different cell components to losses in cell performance has been studied. In general, at low current densities, the electrolyte matrix contributed to the major fraction of potential losses. Mass transfer effects became important at high current densities and were more prominent at the cathode. Electrolyte conductivity and cathode exchange current density seemed to play a limiting role in determining cell performance. Using the model, the maximum power density from a single cell for different cell thicknesses was …
Thermally Stable Gel Polymer Electrolytes, Min-Kyu Song, Young-Taek Kim, Yong Tae Kim, Byung Won Cho, Branko N. Popov, Hee-Woo Rhee
Thermally Stable Gel Polymer Electrolytes, Min-Kyu Song, Young-Taek Kim, Yong Tae Kim, Byung Won Cho, Branko N. Popov, Hee-Woo Rhee
Faculty Publications
To prepare miscible polyethylene glycol diacrylate/polyvinylidene fluoride (PEGDA/PVdF) blend gel polymer electrolytes, low molecular weight (M = 742) liquid PEGDA oligomer was mixed with PVdF-HFP dissolved in ethylene carbonate/dimethyl carbonate/LiPF6 liquid electrolytes, and then cured under ultraviolet irradiation. Room temperature conductivity of PEGDA/PVdF blend films was found to be comparable to that of PVdF-HFP gel polymer electrolytes, and they were electrochemically stable up to 4.6 V vs. Li/Li+. Scanning electron micrographs revealed that PEGDA/PVdF blend electrolytes have pore size intermediate between dense PEGDA and highly porous PVdF-HFP. It was confirmed by weight change measurement that liquid electrolyte …