Mathematical modeling of a sealed nickel-cadmium cell /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | A mathematical model for a sealed secondary nickel-cadmium (Ni-Cd) cell is developed to investigate the dynamic performance of the cell charge and discharge processes. Concentrated solution theory and macro-homogeneous porous electrode theory are used to characterize the transport phenomena of the electrolyte and other species in the porous electrodes and the separator. Other physical fundamentals, such as Ohm's law, are employed to describe the electrical and other physical processes within the cell. The model is designed to predict the distributions of electrolyte concentration, oxygen concentration, potential, current density, electrode porosity, electrochemical reaction rate, and active material as functions of time. The model may be used to evaluate the influences of all the physical, design, and operation parameters, such as active surface area, diffusion coefficients, exchange current density, electrode thickness, active material loading level, saturation level of electrolyte, discharge or charge rate, and operating temperature, on the behavior of a Ni-Cd cell. This model will aid in finding the proper cell design parameters and operating conditions for optimal cell performance. A sensitivity analysis of the cell performance with respect to important input parameters is performed. This analysis reveals that the most influential physical parameter on the cell performance is the effective exchange current density (a[max]i[o,ref]) and the most critical cell design parameter is the active material loading level, L. The chronoamperometric experiments of a nickel hydroxide electrode indicate that the solid state diffusion process in the nickel hydroxide electrode is important. A thin layer reaction model is proposed to characterize the diffusion process in the solid phase of the nickel hydroxide electrode. A parameter estimation technique is used to fit the model to the experimental data. The results indicate that the proton diffusion coefficient is a function of the electrolyte concentration, the state of charge, and the content of cobalt additives. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemical Engineering." |
| Physical Description: | xiv, 178 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |