Orientador: Ennio Peres da Silva / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-09T17:40:54Z (GMT). No. of bitstreams: 1 Sordi_Alexandre_D.pdf: 39903144 bytes, checksum: 0283389433e393e30a63d2f0583d00df (MD5) Previous issue date: 2007 / Resumo: O objetivo desse trabalho foi a modelagem de sistemas de células a combustível (CaCs) operando com o gás de gaseificação de biomassa. Dois tipos de CaCs foram consideradas no estudo: a PEMFC (Proton Exchange Membrane Fuel Cell) e a SOFC (Solide Oxide Fuel Cell). A primeira opera com hidrogênio de alta pureza e a concentração permissível de monóxido de carbono no gás combustível é de 10 _mol.mol-1; então, o sistema deve conter módulos de reforma e purificação da mistura gasosa. A segunda, devido à alta temperatura de operação, pode usar a mistura gasosa diretamente sem restrição quanto ao monóxido de carbono. A metodologia consistiu na análise termodinâmica dos sistemas modelados, visando determinar as irreversibilidades nos processos e as eficiências de primeira e segunda lei; isto foi feito considerando misturas gasosas produzidas por diferentes processos de gaseificação. O estudo demonstrou a importância de um reator de reforma para o desempenho exergético do sistema PEMFC. Neste, respectivamente as eficiências de primeira e de segunda lei variaram de 39% a 41% e de 26% a 31%, a máxima eficiência de segunda lei ocorre quando o gás de gaseificação apresenta menor fração molar de nitrogênio. Para o sistema SOFC as respectivas eficiências variaram de 48% a 51% e de 34% a 39%. A comparação com o sistema de turbina a gás demonstrou que este é superior em eficiência quando opera em ciclo STIG e o reator de gaseificação é pressurizado. Por outro lado o sistema SOFC é o mais eficiente se as turbinas operarem em ciclo simples e com gaseificador pressurizado / Abstract: The objective of this work was to model fuel cell systems with biomass gasification gas. Two types of fuel cells were considered in the study: PEMFC (Proton Exchange Membrane Fuel Cell) and SOFC (Solide Oxide Fuel Cell). The first uses high-purity hydrogen and the maximum carbon monoxide concentration in the fuel gas it is 10 _mol.mol-1. Therefore, it should have systems of reforming and purification of the gaseous mixture. The other, due to the operating temperature, uses directly the gaseous mixture without restriction to the carbon monoxide. The methodology has consisted in a thermodynamic analysis of modeled systems, seeking to determine irreversibility¿s in the processes and first and second law efficiencies, is this was made considering gaseous mixtures produced by different gasification processes. The study has demonstrated the reformer importance for exergetic performance of PEMFC system. In this, respectively the first and second law efficiencies ranging from 39% to 41% and from 26% to 31%, the maximum second law efficiency is accomplished when gasificaion gas is composed to smaller molar fraction of nitrogen. For SOFC system the respective efficiencies ranging from 48% to 51% and from 34% to 39%. The comparison with gas turbine system has demonstrated that these is superior in efficiency when operates at STIG cycle and the gasification reactor is pressurized. On the other hand SOFC system is more efficient if gas turbines operate in simple cycle and with pressurized gasification reactor / Doutorado / Planejamento de Sistemas Energeticos / Doutor em Engenharia Mecânica

There is a great interest to develop biomass combustion systems for industrial and utility applications. Improved biomass energy conversion systems are designed to provide better combustion efficiencies and environmental friendly conditions, as well as the fuel flexibility options in various applications. The gas derived from the gasification process of biomass is considered as one of the potential candidates to substitute traditional fuels in a combustion process. However, the gascomposition from the gasification process may have a wide range of variation depending on the methods and fuel sources. The better understanding of the combustion features for the Gasified Biomass Gas(GBG) is essential for the development of combustion devices to be operated efficiently and safely at the user-end. The objective of the current study is therefore aiming to achieve data associated with the combustion features of GBG fuel for improving the efficiency and stability of combustion process. The numerical result is achieved from the kinetic models of premixed combustion with a wide range of operating ranges and variety of gas compositions. The numerical result is compared with experimental data to provide a better understanding of the combustion process for GBG fuel. In this thesis the laminar flame speed and ignition delay time of the GBG fuel are analyzed, using 1-D premixed flame model and constant volume model respectively. The result from different kinetics are evaluated and compared with experimental data. The influences of initial temperature, pressure and equivalence ratio are considered, as well as the variation of gas compositions. While the general agreement is reached between the numerical result and experimental data for laminarflame speed prediction, deviations are discovered at fuel-rich region and increased initial temperature. For the ignition delay time, deviations are found in the low-temperature and low pressure regime. The empirical equations considering the influence of initial temperature,pressure and equivalence ratio are developed for laminar flame speed and ignition delay times. The influence of major compositions such as CO, H2 and hydrocarbons are discussed in details in the thesis. Furthermore, a simplified kinetic model is developed and optimized based on the evaluation of existing kinetics for GBG fuel combustion. The simplified kinetic model is expected to be used for simulating the complexc ombustion process of GBG fuel in future studies. / <p>QC 20150511</p>

In this diploma thesis "Cogeneration unit with output 200 kWe" the first part describes the properties, drying and combustion of biomass. The next section deals with the description of the combined production of electricity and thermal energy and gas turbines. In the last part of the diploma thesis is devoted to the design and calculations of thermal cycle in order to achieve maximum efficiency.