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With the ongoing increasing focus on the development of intermittent renewable sources, there is a clear need for energy storage solutions that can handle large fluctuations in power and store large amounts of energy. Hydrogen i seen as a candidate as a possible energy carrier for this purpose, and many hydrogen projects have been seen occurring over the world. In order to enable further development of hydrogen systems for the production and utilization of hydrogen fuel, modeling can be performed to investigate the performance, feasibility, and responses of these systems. There is, however, a need for further development of electrolyzer models for production, and fuel cell models for the utilization of hydrogen fuels. The goal of this thesis is to further develop models of electrolyzers and fuel cells with an electrical engineering perspective to be used in further research. This is done by reviewing relevant research related to these topics and narrowing down the findings into comprehensive, simple, and dynamic models in MATLAB/Simulink. These models are described in this thesis, along with the obtained static and dynamic results of the hydrogen production and utilization systems. The models include the option to parameterize to the steady-state data to replicate the static behavior and specify dynamics in terms of capacitive effects and reactant pressure controls for the fuel cell. The Simulink models created can be utilized to further develop various other system components.

Principles of concurrent development are applied to the design of a small-scale device for converting natural gas or liquefied petroleum gas into hydrogen. The small hydrogen generator is intended for serial production for application in the production of industrial hydrogen, fueling stationary fuel cell power systems and refueling hydrogen-fueled fuel cell electric vehicles. The concurrent development process is contrasted with the traditional, linear development process for petrochemical systems and equipment, and the design is benchmarked against existing small hydrogen generators as well as industrial hydrogen production apparatus. A novel system and hardware design are described, and a single cycle of concurrent development is applied in the areas of catalyst development, thermodynamic optimization, and reactor modeling and design. The impact of applying concurrent development techniques is assessed through economic modeling, and directions for future development work are identified. / Ph. D.

The development of a test apparatus for proton exchange membrane fuel cells is presented. The design of the prototype device is provided in detail along with a description of the apparatus. The evaluation of the functionality and effectiveness of the device included measurement of a polarization curve for a 5-cell, 1 kW stack. An effective test apparatus is imperative for stack performance testing, model evaluation, and investigation of new fuel cell technology. This apparatus was designed to measure and control the mass flow rates of the reactant gases, gas pressures, gas temperatures, gas relative humidity, stack temperature, stack current, and the coolant water flow rate. Additionally, the test apparatus can measure the stack voltage, coolant water resistivity, coolant water temperature change across the stack, and the coolant water pressure drop across the stack. The apparatus was shown to provide adequate control of all necessary variables for stack performance evaluation. / Master of Science

This research addresses the manufacturing problems of the fuel cell in an applied industrial approach with the aim of investigating the technology of manufacturing of Proton Exchange Membrane (PEM) fuel cells, and using this technology in reducing the cost of manufacturing through simplifying the design and using less exotic materials. The first chapter of this thesis briefly discusses possible energy alternatives to fossil fuels, arriving at the importance of hydrogen energy and fuel cells. The chapter is concluded with the main aims of this study. A review of the relevant literature is presented in chapter 2 aiming to learn from the experience of previous researchers, and to avoid the duplication in the current work. Understanding the proper working principles and the mechanisms causing performance losses in fuel cells is very important in order to devise techniques for reducing these losses and their cost. This is covered in the third chapter of this thesis which discusses the theoretical background of the fuel cell science. The design of the fuel cell module is detailed in chapter 4, supported with detailed engineering drawings and a full description of the design methodology. So as to operate the fuel cell; the reactant gases had to be prepared and the performance and operating conditions of the fuel cell tested, this required a test facility and gas conditioning unit which has been designed and built for this research. The details of this unit are presented in chapter 5. In addition to the experimental testing of the fuel cell under various geometric arrangements, a three dimensional 3D fully coupled numerical model was used to model the performances of the fuel cell. A full analysis of the experimental and computational results is presented in chapter 6. Finally, the conclusions of this work and recommendations for further investigations are presented in chapter 7 of this thesis. In this work, an understanding of voltage loss mechanism in the fuel cell based on thermodynamic irreversibility is introduced for the first time and a comprehensive formula for efficiency based on the actual operating temperature is presented. Furthermore, a novel design of a 100W (PEMFC) module which is apt to reduce the cost of manufacturing and improve water and thermal management of the fuel cell is presented. The work also included the design and manufacturing of a test facility and gas conditioning unit for PEM fuel cells which will be useful in performing further experiments on fuel cells in future research work. Taking into consideration that fuel cell technology is not properly revealed in the open literature, where most of the work on fuel cells does not offer sufficient information on the design details and calculations, this thesis is expected to be useful in the manifestation of fuel cell technology. It is also hoped that the work achieved in this study is useful for the advancement of fuel cell science and technology.

This thesis presents a compendium of work related to performance analyses of a proton electrolyte membrane (PEM) fuel cell with two novel design configurations. The finite element based numerical analysis has been carried out to solve the numerical transport models involved in a PEM fuel cell coupled with the flow in a porous medium, charge balance, electrochemical kinetics and membrane water content. The scope of this research work focuses on improving the performance of the PEM fuel cell by optimizing the thermo-fluid properties of the reactant species instead of analysing the complex electro-chemical interactions. Two new design configurations have been numerically analyzed; in the first design approach, a perforated-type gas flow distributor is used instead of a conventional gas flow distributor such as a serpentine, straight or spiral shape; the second design approach examines the effect of reactant flow pulsation on the PEM fuel cell performance. Results obtained from the numerical analyses were also compared with the experimental data and a good agreement was found. Performance of the PEM fuel cell with a perforated-type gas distributor was analyzed at different operating and geometric conditions to explore the merits of this new design configuration. Two-dimensional numerical analyses were carried out to analyze the effect of varying the different operating parameters; threedimensional numerical analyses were carried out to study the variation of different geometric parameters on overall performance of the new design configuration of the PEM fuel cell. The effects of the reactant flow pulsation on the performance of PEM fuel cell were analyzed using a two-dimensional numerical approach where both active and passive design configurations were numerically simulated to generate the pulsations in the reactant flow. The results showed a considerable increase in overall performance of the PEM fuel cell by introducing pulsations in the flow.

In this study, Lithium iron oxide (LiFeO₂ – LFO) was investigated as a new anode material for the high temperature SOFCs. From the DC conductivity measurement in argon containing 5% H₂, LFO exhibits good electronic conductivity of 5.08 Scm⁻¹ at 650 °C. LFO poses a high TEC value of 19.5 x 10⁻⁶ K⁻¹ in air. However, the TEC values of the commonly used 8YSZ and CGO electrolytes are much lower, 10.5 x 10⁻⁶ K⁻¹ and 12.5 x 10⁻⁶ K⁻¹ respectively. In order to resolve the mismatch in the TEC values between the electrode and the electrolyte, button fuel cells were fabricated via tape casting. LFO was infiltrated onto the porous and stable scaffold. Presently, the predominant electrolyte material used for the high temperature SOFC is 8YSZ. Due to this reason, the initial performance of LFO as an anode material was tested on tape-cast 8YSZ electrolyte-supported cell. The 8YSZ electrolyte-supported infiltrated with 30 wt% LFO for the anode and 40 wt% LSF for the cathode achieved a maximum power density of 50 mWcm⁻² at 700 °C in humidified H₂. Increasing the weight loading of LFO to 40 wt% worsen the performance. XRD pattern of the sintered powder containing 50 wt% LFO and 50 wt% 8YSZ confirmed that LFO and 8YSZ react with each other. CGO was considered as an alternative electrolyte material to 8YSZ. XRD pattern of the sintered powder containing 50 wt% LFO and 50 wt% CGO confirmed that they are compatible with each other. The CGO electrolyte supported cell infiltrated with 40 wt% LFO for the anode and 40 wt% LSC for the cathode achieved a maximum power density of 180 mWcm⁻² at 650 °C in humidified H₂. The addition of 10 wt% ceria to the LFO anode enhances the electrochemical activities of the cell. However, the overall performance of the cell decreased due to a larger increase in the series resistance. Since CGO electrolyte is easily reduced when testing at temperature higher than 550 °C, LSGM was used to increase the testing temperature. The 245 µm thick LSGM electrolyte-supported cell infiltrated with 40 wt% LSC and 30 wt% LFO obtained a maximum power density of 227 mWcm⁻² at 700 °C in humidified H₂. Decreasing the electrolyte thickness from 245 µm to 130 µm increased the performance of the cell. The 130 µm LSGM electrolyte-supported cell infiltrated with 40 wt% LSC and 30 wt% LFO was tested with the carbon/carbonate fuel as a HDCFC. Performance measurements of the cell was conducted at 650 °C and 700 °C with N₂ flowing at 20 ml/min. The cell performed better when testing at higher temperature. Recently, there has been great interest in developing a SOFC system for the cogeneration of electricity and valuable C₂ chemicals. The catalytic testing for oxidative methane coupling of methane revealed a high C₂ selectivity for the LFO powder. Cell testing of a sample infiltrated with 40 wt% LSC and 30 wt% LFO also achieved a methane conversion of ~3% and a C₂ selectivity of ~80% in methane at 700 °C.

Thesis (M. Tech. Engineering: Electrical--Vaal University of Technology) / The air-breathing Direct Methanol Fuel Cell (DMFC) and Zinc Air Fuel Cell (ZAFC)were experimentally studied in a climate chamber in order to investigate the impact of climatic environmental parameters such as varying temperature and relative humidity conditions on their performance. The experimental results presented in the form of polarization curves and discharge characteristic curves indicated that these parameters have a significant effect on the performance of these fuel cells. The results showed that temperature levels below 0ºc are not suitable for the operation of these fuel cells. Instead, it was found that air-breathing DMFC is favored by high temperature conditions while both positive and negative effects were noticed for the air-breathing ZAFC. The results of the varying humidity conditions showed a negative impact on the air-breathing DMFC at a lower temperature level but a performance increase was noticed at a higher temperature level. For air-breathing ZAFC, the effect of humidity on the performance was also found to be influence by the operating temperature. Furthermore, common atmospheric air pollutants such as N20, S02, CO and N02 were experimentally investigated on the air-breathing DMFC and ZAFC. At the concentration of 20 ppm, these air contaminants showed to have a negative effect on the performance of both air-breathing DMFC and ZAFC. For both air-breathing DMFC and ZAFC, performance degradations were found to be irreversible. It is therefore evident from this research that the performance of the air-breathing fuel cell will be affected in an application situated in a highly air-polluted area such as Vaal Triangle or Southern Durban. It is recommended the air-breathing fuel cell design include air filters to counter the day-to-day variations in concentration of air pollutants.