Contribuição ao projeto de um reator de reforma a vapor de metanol de uma célula a combustível autônoma

Abstract

Fuel cells are an attractive alternative for generating electricity, especially for equipment to small and medium-sized businesses that have the character of portability. Some models of cells are compact and operate at low temperatures, but this technology coming up in the transport and storage of its primary fuel: hydrogen. Hydrogen is very reactive and its storage generally requires the use of complex systems, often operating at high pressures. Alternatively you can "store" it in the form of liquid fuels with high concentrations of hydrogen, such as methanol, which can be easily stored and can be directly converted to hydrogen by steam reforming reaction. This process is basically the reaction between methanol and water vapor, producing hydrogen, carbon monoxide and carbon dioxide, a second endothermic overall reaction. The use of methanol as the main reagent in the steam reforming for hydrogen production is very interesting because this alcohol is what has the highest ratio of carbon and hydrogen (4:1), and can be processed at low temperatures and atmospheric pressure. In various processes hydrogen production by steam reforming, occurs the production of carbon monoxide (CO), which is an unwanted byproduct, being a poison to various types of fuel cells. Both the project and determining the optimal operating conditions of a reactor for steam reforming of methanol in order to integrate the fuel cells may find importance in modeling and simulation aids. However, there are few studies in literature involving modeling, simulation and design of reactors for steam reforming of methanol and theoretical studies aimed at determining the optimum operating conditions to minimize the production of carbon monoxide. In this context, the objective of this study was to develop a mathematical model of a reactor for methanol steam reforming, simulate it and validates it against experimental data from literature. The mathematical model was implemented in MATLAB and solved numerically and comparison of its predictions in different experimental conditions indicates that both the model developed as the methodologies for its numerical solution were adequate. From this model were validated designed three reactors for steam reforming to meet with appropriate flow of hydrogen fuel cells available in three commercial fuel cell, and determine the operating conditions that minimize the generation of carbon monoxide and provide an effluent stream reactor with acceptable levels of CO that can be introduced directly into the fuel cell without requiring an intermediate step of removing this contaminant.