Orientadores : Luiz Fernando Milanez, Jose A. Velasquez / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T09:13:18Z (GMT). No. of bitstreams: 1 Bueno_AndreValente_D.pdf: 1858642 bytes, checksum: 5d8ef42f35d6898a67cb77a3c73c0b7d (MD5) Previous issue date: 2006 / Resumo: As conseqüências da adição de biodiesel ao óleo diesel foram estudadas estabelecendo-se relações de causa e efeito entre o desempenho do motor e os processos de combustão e formação de mistura. Foram incluídos, nesta discussão, aspectos como emissões poluentes, formação de mistura, dinâmica do processo de combustão, eficiência de conversão do combustível,desempenho do motor em carga máxima e consumo específico.Utilizaram-se, sob tal propósito, técnicas tradicionalmente associadas à pesquisa e ao desenvolvimento dos motores de ciclo diesel, tais como a análise de liberação de energia, a análise exergética e ensaios dinamométricos. Devido às pequenas variações observadas nos parâmetros opcionais do motor com a introdução do biodiesel, algumas modificações nos métodos aplicados para a coleta de dados experimentais e nos modelos empregados em seu processamento se mostraram necessárias. Dentre tais ajustes, pode-se destacar a formulação de um novo modelo de análise exergética para os processos ocorrentes no cilindro e a utilização de um arranjo inédito de sistema indicador. Demonstrou-se que a adição de biodiesel em baixas concentrações favorece a conversão da exergia do combustível em trabalho no interior do cilindro, proporcionando uma elevação na eficiência de operação do motor. Para os combustíveis analisados, que compreendem a adição de até 20% de biodiesel em volume, a mistura contendo 10% desta substância ofereceu as melhores características quanto ao desempenho e ao consumo específico / Abstract: The consequences of the biodiesel blends with diesel fuel were analyzed establishing cause and effect relationships between the engine performance and the combustion and mixture preparation processes. In this investigation, aspects like pollutant emissions, mixture preparation,dynamic of the combustion process, fuel conversion efficiency, performance under full load and specific fuel consumption were included.Techniques traditionally associated with diesel engines research and development were utilized for this purpose, including heat release analysis, exergetic analysis and dynamometric bench tests. In order to account for the small effects of the biodiesel introduction on the engine operational parameters, some modifications of the methods and models applied to data acquisition and post-processment were necessary. These modifications include the formulation of a new model for the in cylinder exergetic analysis and a novel arrangement of indicator system. By using the exergetic analysis, it was demonstrated that the blending of biodiesel in low concentrations increases the conversion of fuel exergy into work within the cylinder, causing an elevation on the engine efficiency. For the analyzed fuels, which enclose up to 20% of biodiesel addition in volume, the 10% biodiesel blend has presented the best results of performance and specific fuel consumption / Doutorado / Termica e Fluidos / Doutor em Engenharia Mecânica

The theme of this thesis is the reaction to fire performanceof wood and other building products, andparticularly thematerial fire properties time to ignition, rate of heat releaseand smoke production. These properties have been measured by asmall-scale fire test method, the Cone Calorimeter, andpresented for different types of building products. Uncertainty analysis, included instrument and assumptionuncertainty, has been performed for the case that both O2 andCO2 are measured for calculation of the rate of heat release inthe Cone Calorimeter. The partial derivatives for theuncertainty analysis are given. The relative uncertainty forthe rate of heat release measurements in the Cone Calorimeteris between ±5% to ±10% for rate of heat releasevalues larger than about 50 kW/m2. The time to ignition in the Cone Calorimeter is compatiblewith the time to ignition in the ISO Ignitability test, whichis the main test method for measuring time to ignition. Thetime to ignition is an increasing linear function of density.The rate of heat release in the Cone Calorimeter is dependentof material thickness and of use of retainer frame. Thematerial thickness gives the heat release curve duration andshape. Thin materials have short burning time and two maximumvalues. Thick materials have long burning time and when thematerial is thicker than about 35 mm no second maximum appears.When the retainer frame is used the actual exposed surface isreduced from 0.01 m2 to 0.0088 m2, the rate of heat release isreduced and the burning time is increased. A comparison ofresults with and without use of the retainer frame gives thenequal results when the exposed area is set to 0.0088 m2 in thecase of using the retainer frame. The time to flashover in the full-scale room corner test waspredicted on the basis of Cone Calorimeter data at 50 kW/m2 bya power law of ignition time, the total heat release calculatedover 300 s after ignition and the density of the product. Therelation gives a simple relation to evaluate if a productreaches flashover in the room corner test. The smoke production has also been measured in the ConeCalorimeter. The white light and the laser smoke measurementsystems have shown similar results. There is a correlationbetween Cone Calorimeter and room corner test smoke productionwhen the products are divided into groups: those that reachflashover in the room corner test in less than 10 min and thosethat have more than 10 min to flashover. Temperature profilesin wood have been measured in the Cone Calorimeter by a simpletechnique. The effect of fire protective gypsum plasterboardson the charring of wood frame members has been determined andcompared with fullscale furnace wall tests. The protectiveeffects of twenty different boards have been presented. ConeCalorimeter and furnace tests show similar charring of wooduntil the boards fall down in furnace tests. After that, thecharring of wood is higher in the furnace, because the wood isexposed directly to the fire. Keywords:building products, charring of wood, ConeCalorimeter, fire retardant treated wood, fire tests,ignitability, mass loss, rate of heat release, reaction tofire, smoke production, wood products / <p>NR 20140805</p>

Motivado pela grande necessidade da utilização de combustíveis alternativos, o presente trabalho apresenta o estudo experimental e simulação termodinâmica (zero-dimensional) do desempenho de um motor de combustão interna de ignição por compressão utilizando álcool e óleo Diesel. Primeiramente são apresentados definições e conceitos relacionados a motores de combustão interna; a seguir apresenta-se o problema e os objetivos almejados. Posteriomente apresentam-se os resultados obtidos em dinamômetro confrontando-os com uma simulação no software Chemkin®. Dos resultados obtidos em dinamômetro, destacam-se as comparações das curvas características do motor para ambos os combustíveis. Também é discutida a metodologia empregada e as modificações realizadas. Todas as modificações realizadas no motor foram realizadas com o uso de componentes comercialmente disponíveis. Utilizou-se como facilitador da ignição, para o álcool, o \"Princípio do Ponto Quente\". As curvas características para ambos os combustíveis foram obtidas segundo a norma NBR-ISO 1585. Mediu-se, também, consumo de combustível, pressão na câmara de combustão e temperaturas do sistema. Destes dados obtém-se a comparação da pressão de combustão para os dois combustíveis. É feita também a comparação entre as pressões de combustão obtidas com a simulação termodinâmica. Esses resultados, por um lado, sustentam a viabilidade desta substituição entre os combustíveis, por outro lado mostram as dificuldades em se utilizar um combustível alternativo como o álcool nos motores de ignição por compressão. / Due to a huge necessity to use alternatives fuels, this study presents an experimental performance investigation and it\'s thermodynamics simulation (zero-dimensional) of an ignition engine Diesel cycle working with ethanol and Diesel. First of all some definitions and concepts related to internal combustion engines are given. Following this, an explanation of the problem and the aims are exposed; after that the dynamometer data have been presented and compared with engine simulation carried out with Chemkin®. From the dynamometer data, characteristics performance curves for both fuels can be highlighted. The applied methodology and technical modifications are also presented. All changes proposed in the engine are based on commercial components. To facilitate the mixture ignition into the combustion chamber, the glow plugs principle was used. Dynamometer tests were carried out according to norms NBR ISO 1585. Fuel consumption, chamber pressure and temperatures were also acquired. From these data combustion pressure for both fuels are compared. The experimental pressure is compared also to the results obtained with the thermodynamics simulation. The present results show the possibility of interchangeability between the ethanol and diesel in a compression ignition engines.

Motivado pela grande necessidade da utilização de combustíveis alternativos, o presente trabalho apresenta o estudo experimental e simulação termodinâmica (zero-dimensional) do desempenho de um motor de combustão interna de ignição por compressão utilizando álcool e óleo Diesel. Primeiramente são apresentados definições e conceitos relacionados a motores de combustão interna; a seguir apresenta-se o problema e os objetivos almejados. Posteriomente apresentam-se os resultados obtidos em dinamômetro confrontando-os com uma simulação no software Chemkin®. Dos resultados obtidos em dinamômetro, destacam-se as comparações das curvas características do motor para ambos os combustíveis. Também é discutida a metodologia empregada e as modificações realizadas. Todas as modificações realizadas no motor foram realizadas com o uso de componentes comercialmente disponíveis. Utilizou-se como facilitador da ignição, para o álcool, o \"Princípio do Ponto Quente\". As curvas características para ambos os combustíveis foram obtidas segundo a norma NBR-ISO 1585. Mediu-se, também, consumo de combustível, pressão na câmara de combustão e temperaturas do sistema. Destes dados obtém-se a comparação da pressão de combustão para os dois combustíveis. É feita também a comparação entre as pressões de combustão obtidas com a simulação termodinâmica. Esses resultados, por um lado, sustentam a viabilidade desta substituição entre os combustíveis, por outro lado mostram as dificuldades em se utilizar um combustível alternativo como o álcool nos motores de ignição por compressão. / Due to a huge necessity to use alternatives fuels, this study presents an experimental performance investigation and it\'s thermodynamics simulation (zero-dimensional) of an ignition engine Diesel cycle working with ethanol and Diesel. First of all some definitions and concepts related to internal combustion engines are given. Following this, an explanation of the problem and the aims are exposed; after that the dynamometer data have been presented and compared with engine simulation carried out with Chemkin®. From the dynamometer data, characteristics performance curves for both fuels can be highlighted. The applied methodology and technical modifications are also presented. All changes proposed in the engine are based on commercial components. To facilitate the mixture ignition into the combustion chamber, the glow plugs principle was used. Dynamometer tests were carried out according to norms NBR ISO 1585. Fuel consumption, chamber pressure and temperatures were also acquired. From these data combustion pressure for both fuels are compared. The experimental pressure is compared also to the results obtained with the thermodynamics simulation. The present results show the possibility of interchangeability between the ethanol and diesel in a compression ignition engines.

No description available.

Fires in buildings ranging in size from small residential houses to large office buildings and sports stadiums pose significant threats to human safety. Many advances have been made in the area of fire behaviour modeling and have lead to much safer, and more efficient fire protection engineering designs, saving countless lives. Fire, however, is still a difficult phenomenon to accurately model and the most important quantity used to describe a fire is the heat (energy) release rate (HRR). Predictions of the fire hazard posed by mattresses, using relatively simple modeling techniques, were investigated in this research work and compared to full-scale experimental results. Specifically, several common methods of predicting the HRR from a mattress fire were examined. Current spatial separation guidelines, which exist in order to mitigate fire spread between buildings, were used to predict radiation heat flux levels emitted by a burning building and compared to experimental results measured in the field. Enclosure ceiling temperatures, predicted using the Alpert temperature correlation, and average hot gas layer temperature predictions were also compared to experimental results. Results from this work indicate that the t-squared fire heat release rate modeling technique combined with the common Alpert ceiling temperature correlation, provide a reasonable prediction of real-life fire temperatures as results within 30% were obtained. The cone calorimeter was also found to be a useful tool in the prediction of full-scale fire behaviour and the guidelines used for spatial separation calculations were found to predict the radiant heat flux emitted by a burning building reasonably well.

Fires in buildings ranging in size from small residential houses to large office buildings and sports stadiums pose significant threats to human safety. Many advances have been made in the area of fire behaviour modeling and have lead to much safer, and more efficient fire protection engineering designs, saving countless lives. Fire, however, is still a difficult phenomenon to accurately model and the most important quantity used to describe a fire is the heat (energy) release rate (HRR). Predictions of the fire hazard posed by mattresses, using relatively simple modeling techniques, were investigated in this research work and compared to full-scale experimental results. Specifically, several common methods of predicting the HRR from a mattress fire were examined. Current spatial separation guidelines, which exist in order to mitigate fire spread between buildings, were used to predict radiation heat flux levels emitted by a burning building and compared to experimental results measured in the field. Enclosure ceiling temperatures, predicted using the Alpert temperature correlation, and average hot gas layer temperature predictions were also compared to experimental results. Results from this work indicate that the t-squared fire heat release rate modeling technique combined with the common Alpert ceiling temperature correlation, provide a reasonable prediction of real-life fire temperatures as results within 30% were obtained. The cone calorimeter was also found to be a useful tool in the prediction of full-scale fire behaviour and the guidelines used for spatial separation calculations were found to predict the radiant heat flux emitted by a burning building reasonably well.

This thesis consists of analysis of three different data sets: (i) Aircraft-based eddy correlation data collected above irrigated and non-irrigated agricultural land in Southern California during the California Ozone Deposition Experiment (CODE) summer 1991; (ii) micrometeorological tower data, collected over grape and cotton canopies as part of CODE; (iii) aircraft-based eddy correlation flux data above two grid sites in the Canadian boreal forest during the Boreal Ecosystem-Atmosphere Study (BOREAS), spring and summer of 1994 and 1996. / Results from the CODE aircraft data document composition and size of the dominant structures, which transport heat and gases (H2O, CO 2 and ozone) over water stressed and non-water stressed surfaces, and the relative frequency with which structures carrying only a single scalar, or given combinations of scalars, were encountered along the flight paths. Interpretation of results provides further evidence for the existence of a second (nonphysiological) sink for ozone. The relative preponderance of structures that carry moisture, carbon dioxide and ozone simultaneously, particularly in the gradient-up mode, reflects the importance of vegetation as co-located source/sink for these scalars. The detrending procedures described in this study may help to define a more effective separation between local and mesoscale events in biosphere-atmosphere interaction. / Results from the CODE tower data indicates a single vegetated ozone sink for the grape site, but a vegetated as well as a non-vegetated sink for the cotton site. For both sites, structures simultaneously transporting significant flux contributions of CO2, H2O, heat and ozone dominate during unstable conditions. During stable conditions, unmixed single flux structures dominated over cotton but not over grape. The results of this study contribute empirical evidence about the relationship between ozone uptake and the physical and physiological state of vegetation, as well as the limitations placed on eddy scales in simulation models. / Results from the BOREAS aircraft data shows a decoupling between the surface and the atmosphere, where the patterns of vegetation, greenness and surface temperature may be quite dissimilar to those of the fluxes of sensible heat, latent heat and---to a lesser degree---CO2. Reasons for this lie in the extraordinary boundary layer conditions, high vapour pressure deficit, moist soil and hot canopies, and the response of the vegetation to these conditions. Analysis of the coherent structure compositions to some extent permits the characterization of the different sources and sinks. Overall, this study shows the importance of understanding the various interacting components of soil, vegetation and atmosphere when attempting to design process-based models for predictions in 'micrometeorologiacally' complex ecosystems.

Disertacijos tyrimų aktualumą lemia energijos panaudojimo efektyvumo didinimas bei aplinkos taršos mažinimas transporto sektoriuje. Darbe sprendžiami eksperimentiniai, matematinio modeliavimo ir metodologiniai uždaviniai, siekiant kompleksiškai ištirti dyzelinių variklių, dirbančių II kartos RRME, alkoholio ir dyzelino mišiniais, eksploatacinius darbo rodiklius. Disertacijoje analizuotas ir įvertintas degalų mišinių panaudojimo lengvųjų automobilių ir pagalbiniame laivo dyzeliniuose varikliuose efektas. Tiriamojo darbo problematika, tikslas, uždaviniai suformuoti išanalizavus transporto sektoriaus sandarą, svarbą oro taršos ir energijos sunaudojimo srityse bei ES strateginius planus. Laboratorijos bei eksploatacijos sąlygomis ištirti I, II kartos biodegalų ir dyzelino mišiniai. Tyrimams panaudotuose varikliuose išbandyti butanolio ir metanolio su rapso metil/butilesteriais bei dyzelino 2 ir 3 komponentų mišiniai. Išbandyti II kartos RRME mišiniai: Sėjamosios judros (lot. Camelina sativa) kartu su kiaulienos RRME ir mikro dumblių (lot. Clorella sp.). Atlikti dyzelino ir mišinių palyginamieji variklinių savybių tyrimai. Panaudojant mišinius, energijos panaudojimo efektyvumas didėja ~1–4 %; esant šiek tiek išaugusiai NOX koncentracijai, CO, CH koncentracijos sumažėjimas siekia iki 20 %, o deginių dūmingumas – 55–85 %. Įvertinti terminės ir mechaninės apkrovos kriterijai, indikuojantys variklio konstrukcinį patikimumą dirbant dyzelinu ir degalų mišiniais. Ištirta biodyzelinų... [toliau žr. visą tekstą] / The relevance of dissertation research is determined increasing efficiency of energy use and reduction of environmental pollution in the transport sector. In order to accomplish the complex research of diesel engines (running on 2nd generation FAME, alcohol and diesel blends) performance indicators the experimental, simulation and methodological tasks are solved in dissertation. The analysis and evaluation of effect of fuel blends use in passenger car and vessel auxiliary diesel engines is presented in dissertation. The problem, aim, tasks of research work formulated after analysis of transport sector structure, the importance of air pollution and energy consumption and the EU's strategic plans. The blends of 1st and 2nd generation biofuels were investigated using laboratory equipment and in the exploitation conditions. 2 and 3 component blends of diesel, methanol, butanol, rape methyl/butyl esters were tested in diesel engines. Tested 2nd generation FAME blends: False flax (lat. Camelina sativa) with pork lards FAME and sea algae (lat. Clorella sp.). The comparable research of parameters while engine ran on diesel and blends was carried out. In the case of blends use the energy efficiency increases ~1–4%; at slightly increased NOX concentration the CO and CH concentrations decreased up to 20% and exhaust smoke, and smokiness decreased – 55–85%. The evaluation of thermal and mechanical load criteria which indicate 1.9 TDI 1Z engine reliability operating on diesel fuel and... [to full text]

Fossil fuel reserves are projected to be decreasing, and emission regulations are becoming more stringent due to increasing atmospheric pollution. Alternative fuels for power generation in industrial gas turbines are thus required able to meet the above demands. Examples of such fuels are synthetic gas, blast furnace gas and coke oven gas. A common characteristic of these fuels is that they are multi-component fuels, whose composition varies greatly depending on their production process. This implies that their combustion characteristics will also vary significantly. Thus, accurate and yet flexible enough combustion sub-models are required for such fuels, which are used during the design stage, to ensure optimum performance during practical operating conditions. Most combustion sub-model development and validation is based on Direct Numerical Simulation (DNS) studies. DNS however is computationally expensive. This, has so far limited DNS to single-component fuels such as methane and hydrogen. Furthermore, the majority of DNS conducted to date used one-step chemistry in 3D, and skeletal chemistry in 2D only. The need for 3D DNS using skeletal chemistry is thus apparent. In this study, an accurate reduced chemical mechanism suitable for multi-component fuel-air combustion is developed from a skeletal mechanism. Three-dimensional DNS of a freely propagating turbulent premixed flame is then conducted using both mechanisms to shed some light into the flame structure and turbulence-scalar interaction of such multi-component fuel flames. It is found that for the multi-component fuel flame heat is released over a wider temperature range contrary to a methane flame. This, results from the presence of individual species reactions zones which do not all overlap. The performance of the reduced mechanism is also validated using the DNS data. Results suggest it to be a good substitute of the skeletal mechanism, resulting in significant time and memory savings. The flame markers commonly used to visualize heat release rate in laser diagnostics are found to be inadequate for the multi-component fuel flame, and alternative markers are proposed. Finally, some popular mean reaction rate closures are tested for the multi-component fuel flame. Significant differences are observed between the models’ performance at the highest turbulence level considered in this study. These arise from the chemical complexity of the fuel, and further parametric studies using skeletal chemistry DNS would be useful for the refinement of the models.