Sugarcane is a major crop in many countries. It is the most abundant lignocellulosic material in tropical countries such as South Africa. It is one of the plants with the highest bioconversion efficiency. The sugarcane crop is able to efficiently fix solar energy, yielding some 55 tons of dry matter per hectare of land annually. After harvest, the crop produces sugar juice and bagasse. Sugarcane bagasse is a residue that results from the crushing of sugarcane in the sugar industry. It is a renewable feedstock that can be used for power generation and manufacturing cellulosic ethanol. As biomass, sugarcane bagasse holds promise as a fuel source since it can produce more than enough electricity and heat energy to supply the needs of a common sugar factory. However, in the sugarcane industry the bagasse is currently burnt inefficiently in boilers that provide the heating for the industry. This project seeks to investigate the possibility of gasifying sugarcane bagasse as an efficient conversion technology. The investigation is necessary because fuel properties govern the gasifier design and ultimately, the gasification efficiency. Proximate and ultimate analysis of sugarcane bagasse was conducted after which the results were used to conduct a computer simulation of the mass and energy balance during gasification. The kinetic investigation undertaken through the TGA and DTG analyses revealed the activation energy and pre – exponential factor which were obtained by the model – free Kissinger method of kinetic analysis and were found to be 181.51 kJ/mol and 3.1 × 103/min respectively. The heating value of sugarcane bagasse was also measured and found to be 17.8 MJ/kg, which was used in the calculation of the conversion efficiency of the gasification process. Fuel properties, including moisture content and gasifier operating parameters were varied in order to determine optimum gasifier operating conditions that results in maximum conversion efficiency. The highest conversion efficiency was achieved at low moisture content after computer simulation of the gasification process. Moisture content also affected the volume of CO and H2 as the former decreases with increasing moisture content while the latter increases with increasing moisture content, accelerating the water – gas reaction. Scanning electron microscope fitted to an Energy dispersive X – ray spectroscopy was also used in order to view the shape and size distribution as well as determine the elemental composition of sugarcane bagasse. The results obtained established that the fuel properties and gasification conditions affect the conversion efficiency. During computer simulation, it was established that smaller particle size resulted in higher conversion efficiency. The smaller throat diameter also resulted in higher conversion efficiency. The throat angle of 25° also resulted in higher conversion efficiency. The temperature of input air was also found to be one of the major determining factors in terms of conversion efficiency. The dissertation presents the proximate and ultimate analysis results as well as the kinetic analysis results. The SEM/EDX analysis as well as the computer simulation results of the gasification process is also presented. The major contribution of this project was on the investigation of the gasification characteristics of sugarcane bagasse and the utilization of these in the design of a laboratory scale sugarcane bagasse gasifier with enhanced conversion efficiency through computer simulation.

This thesis demonstrates the utility of computer simulation in the modelling of hydro-electric and thermal plant operations. It focuses on models of selected facilities in the British Columbia Hydro and Power Authority's integrated system. Four different simulation models are developed. Each successive model develops a variation of the basic program to accommodate the different hydro-electric and thermal plant configurations. When more than one energy producing facility is included in a particular simulation, they are operated on a coordinated basis. The purpose of the models is to assess the energy producing capabilities of alternative configurations. Two types of experiments are performed on the models: model configuration and operating coordinating policy. In terms of the hydro-electric facilities, the scope of the models extends from the simulation of river inflows to reservoirs, through the energy generation phase, to the resultant down river flow. Generally, thermal plant operation is a function of reservoir status. The IBM GPSSV computer language is used in the modelling process. By considering the simulation output over the two types of experiments, it is possible to draw conclusions concerning the ability of certain facility configurations to meet specified energy demands. These conclusions can facilitate B.C. Hydro in the management of its integrated system with respect to planning the construction of new facilities and establishing coordinating-operating policies. Additionally, the value of using GPSSV in the modelling process is discussed. / Business, Sauder School of / Graduate

Orientadores: Milton Mori, Alexandre de Paula Peres / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T02:14:15Z (GMT). No. of bitstreams: 1 Bernardo_Sergio_D.pdf: 16858562 bytes, checksum: 146132fc4ed6476801c980face63fe50 (MD5) Previous issue date: 2004 / Resumo: Este trabalho é fruto do esforço iniciado por pesquisadores do Laboratório de Modelagem e Simulação de Processos Químicos (FEQ-UNICAMP) visando estudar o escoamento do gás em ciclones. A premissa foi buscar a consolidação das informações já obtidas, usando como ferramenta para tal finalidade as modernas técnicas da Fluidodinâmica Computacional (CFD). O trabalho foi dividido em duas frentes: análise do escoamento monofásico (gás) e do escoamento bifásico (gás-sólido), tendo como foco o mapeamento do campo de velocidade, pressão e eficiência por meio de um modelo CFD tridimensional. O estudo foi embasado em resultados experimentais disponíveis na literatura científica, como também em experimentos numéricos desenvolvidos previamente por outros pesquisadores deste grupo de pesquisa. A busca incessante por informações que ajudem a elucidar o entendimento do complexo sistema de escoamento que ocorre no interior de um ciclone foi o marco inicial dos trabalhos do grupo. E neste trabalho apresenta-se a confirmação de informações anteriormente levantadas, como também novas perspectivas para a melhor compreensão do mecanismo de operação de um ciclone. As malhas numéricas tridimensionais foram geradas utilizando os pré-processadores Gambit e ICEM CFD HEXA e a partir daí os trabalhos foram desenvolvidos através de experimentos numéricos usando os pacotes computacionais em CFD: FLUENT (versão 6.0) e CFX (versões 5.5.1, 5.6 e 5.7) que fazem uso do método dos volumes finitos com variáveis co-localizadas (na qual todas as variáveis usam o mesmo volume de controle para realizar todas as integrações) na solução do sistema de equações de transporte, através de coordenadas generalizadas. Para adentrar no complexo campo da turbulência do escoamento, modelos de turbulência tais como RSM, LES e DES foram testados em simulações que foram capazes de extrair informações significativas a respeito do comportamento do escoamento do gás quando da presença de partículas sólidas. O trabalho abriu, ainda, uma ramificação para avaliar a influência de alterações na geometria do ciclone na fluidodinâmica de seu escoamento. Os resultados mostraram que a metodologia de trabalho empregada é adequada quanto à reprodução do comportamento fluidodinâmico dos escoamentos monofásico e bifásico em ciclones e que alterações geométricas propostas apontam para melhores resultados no processo de separação gás-sólido no equipamento / Abstract: This work is the result of the efforts of the CFD research group of the Chemical Processes Modeling and Simulation Laboratory located at FEQ-UNICAMP to study gas and gas-particle flow in a cyclone. The starting point was to consolidate previous information in cyclone flow using current CFD techniques. Two research lines were applied: the first one has studied gas flow and the second one was involved in the gas-solid flow study. These . analyses were focused on fluid dynamics parameters like tangential, axial and radial velocities profiles, pressure and coIlection efficiencies using a three-dimensional CFD model. Experimental and numerical results available in the literature were used to validate simulation data obtained in this work. Three-dimensional numerical grids were constructed using pre-processors like GAMBIT and ICEM CFD HEXA. The numerical simulations were performed using the commercial CFD codes FLUENT (v6.0) and CFX (v5.5.1, 5.6 and 5.7). These softwares make use of fmite volume method to solve transport equation system, using generalized coordinates. Turbulence models, like RSM, LES and DES were tested on simulations to extract important information about gas-solid flow profile. In addition, the influence of geometrical modifications on cyclone fluid dynamics was studied. The results showed that the methodology applied in this work is consistent to reproduce the fluid dynamic behavior of gas and gas-solid flow in a cyclone. Numerical results obtained here are in agreement with experimental results and other numerical data available in the literature. The modifications in the geometry proposed here indicate improvements in gas-solid coIlection efficiencies in the equipment. We believe that this study wiIl contribute to increase the knowledge on cyclone fluid dynamics / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

No description available.

1.1\xThis study proposed a particle-set distributed hydrological model for the dynamic simulation of rainfall-runoff process. With the supports of remote sensing, GIS, terrain analysis and distributed computing techniques, a representation-simplified and physically-based high-performance watershed framework has been developed. It simplifies the underlying watershed with a flow path network model, and represents the moving surface flow with independent runoff particles.;1.2\xThe original idea was to investigate a real-time modeling system for the space-time dynamics of increasingly frequent extreme rainfall events. Short-term heavy rains may cause further damages by spawning floods and landslides. It is quite essential to understand how the rainfall water moves across the watershed surface as early as possible. A modelling system with high-performance in simulation efficiency and space-time prediction accuracy would be very desirable.;1.3\xWatershed modeling is the primary way to explore the hydrological cycle at a local scale. Existing models are classified as empirical lumped, conceptual semi-distributed and physically-based distributed models. The first two types of models have focused more on predicting outlet discharges rather than estimating spatiotemporal flow dynamics. The application of physically-based models has always been hampered by some common shortcomings like over-parameterization, inflexibility and computational burden. With the increasing support from terrain analysis and parallel computing techniques, a number of previous studies have made some efforts to improve the performance in dynamic and real-time simulation. However, research gaps still exist in realistic representation, physical description and real-time simulation.;1.4\xThis study, therefore, developed the particle-set modeling system on the basis of flow path network model. This one-dimensional topological structure was created beforehand to represent the three-dimensional watershed, and a series of particle beams were dynamically generated to simulate the surface flow. Under the control of flow velocities, these runoff particles would keep on moving along with the flow paths, which can represent the spatial distributions of surface water in time.;1.5\xTo validate the proposed particle-set framework, a prototype of particle-set system was implemented by programming methods with the assistance of third-party platforms. Three experiments were undertaken to respectively evaluate the performance in prediction accuracy, simulation efficiency and parameter sensitivity. More specifically, a total of 10 rainfall events and up to 128 computer processors were tested. In addition, the influences of underlying spatial scale and source sampling density on hydrological responses were explored with comparative tests.;1.6\xThe accuracy validation comes in two parts, the representation loss in terrain analysis, and the discharge error in hydrological modeling. The experimental results indicate that the TIN-based flow path network has maintained the terrain features at a very high level with much less data storage, and the particle-set framework has achieved quite acceptable predictions of outlet discharges. Besides, the efficiency evaluation concerns with two aspects, parallel portion and parallel efficiency. The speed-up results indicate that about 99% of the computational workloads can be computed in parallel, and the particle-based scheme can achieve almost the ideal parallel efficiency. In addition, the sensitivity test focuses also on two parameters, underlying spatial scale and source sampling density. The preliminary results show that the particle-set model has shown a good reliability and stability as scale gets coarser or density becomes sparser.;1.7\xThis study will contribute to the understanding of short-term rainfall-runoff events at a basin scale. The particle-set distributed hydrological model has been proven to provide real-time spatio-temporal dynamics of surface flow. Further studies would still be required to apply it to real world scenarios.;1.8\xKeywords: terrain analysis, watershed hydrology, rainfall-runoff process, flow path network, particle system, parallel computing

Orientador: Aguinaldo Robinson de Souza / Banca: Lucas Colucci Ducati / Banca: José Humberto Dias da Silva / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi / Resumo: Neste trabalho buscamos, após gerar simulações computacionais usando a teoria DFT e como instrumento o programa Crystal09, na supercélula de 32 átomos do GaN, comparar a estrutura não otimizada com a otimizada, a fim de compreender suas principais diferenças. Em uma segunda etapa da pesquisa, analisamos os efeitos das vacâncias de átomos de gálio e de nitrogênio em mais de um átomo na mesma estrutura, simulando defeitos nesse material. Por fim, estudamos os efeitos indiretos da variação da temperatura no gap de energia. Pudemos concluir que, em relação a energia total e o valor do gap de energia, as estruturas otimizada e não otimizado apresentam valores muito próximos, não apresentando muitas vantagens o processo de otimização. Em alguns casos, o material tornou-se degenerado do tipo p ou n, de acordo com a vacância apresentada. Simulamos e analisamos os efeitos que o aumento da temperatura causa nos valores dos parâmetros a e c na célula unitária, determinando o gap de energia, pudemos observar a sua diminuição, favorecendo a condutividade elétrica do material / Abstract: In this research we seek, after generating computer simulations using the DFT theory and the Crystal09 program as a tool in the supercell of 32 atoms of GaN, compared to non-optimized structure with optimized in order to understand their differences. In a second stage of the research, analyzed the effects of vacancies and gallium atoms of nitrogen in more than one atom in the same structure, simulating defects in this material. Finally, we study the indirect effects of temperature variation in the energy gap. We concluded that, in relation to total energy and the value of the energy gap, the optimized and non-optimized structures have very similar values, not presenting many advantages the optimization process. In some cases, the material became degenerate p-type or n-type, in accordance with the vacancy appears. We simulate and analyze the effects that the increase in temperature causes the values of the unit cell parameters a and c, determining the energy gap, we could observe its decrease, favoring the electrical conductivity of the material / Mestre

Master of Science

<p>The objective of this research project is to develop a computer assisted education system to enable users to effectively learn the Visual Simulation Environment (VSE), simulation and modeling. The vast amount and the relatively high complexity of the knowledge contained in the VSE, simulation, and modeling, dictate a need to provide an effective mechanism for assimilating the knowledge. This report describes the Learning Support System (LSS), a tool developed to present documents to users in an effective manner, thereby facilitating access to the knowledge contained within the documents. Text, graphics and animations are used within documents to support the learning process. The hierarchical organization of the information structure, the use of hypertext links, and search capabilities facilitate the efficient transfer of relevant information. The LSS thus incorporates features that contribute to an improved learning process. Usability tests across a wider spectrum of users would enable the LSS to be modified to meet the needs of the diverse user community. The LSS will be used in the Spring '95 Simulation classes to aid in the teaching of simulation and modeling. Feedback from users will shape the future enhancements to LSS. Future technology changes are expected to provide advantages for building on the LSS research project described herein. / Master of Science

Master of Science

The objective of the research described herein is to develop a prototype data analysis software tool integrated within the Visual Simulation Environment (VSE). The VSE is an integrated set of software tools that provide computer-aided assistance throughout the development life cycle of visual discrete-event simulation models. Simulation input and output data analyses are commonly needed in simulation studies. A software tool performing such data analysis is required within the VSE to provide automated support for input data modeling and output data analysis phases of the model development life cycle. The VSE DataAnalyzer provides general statistics. histograms, confidence intervals, and randomness tests for the data sets. It can also create C modules for generating random variates based on a collected set of data. Furthermore, the VSE DataAnalyzer possesses the basic file management, editing, printing, and formatting functionalities as well as a complete help feature. It has been used in a senior-level Simulation and Modeling course, and the feedback from the students has been positive. New functionalities can easily be added to the VSE DataAnalyzer due to its object-oriented software structure. The VSE DataAnalyzer is yet another software tool created to provide more comprehensive automated support throughout the visual simulation model development. / Master of Science