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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Bestämning av pannverkningsgrad – Ålidhems Värmeverk : Jämförelse mellan direkt- och indirekt metod / Determination of boiler efficiency – Ålidhem heating plant : Comparison between the input-output method and the energy balance method

Söderlund, Martin January 2015 (has links)
På uppdrag från Umeå Energi AB ska två av deras rostereldade värmepannor (panna 6 och 7) undersökas med avseende på pannverkningsgraden. Umeå Energi genomför i dagsläget månadsvisa kontroller av pannverkningsgraden beräknade med den direkta metoden. Denna beräkningsmetod är dessvärre ganska otillförlitlig, vilket medför att en noggrannare undersökning av pannverkningsgraden krävs. Av denna anledning så beräknades pannverkningsgraden med den indirekta beräkningsmetoden, vilket resulterade i ett mer tillförlitligt resultat där även pannans förlustfaktorer bestämdes. Pannverkningsgraden beräknades och analyserades med hänsyn till de ingående förlustfaktorerna vid samma nyttiga effekt för båda pannorna. För att genomföra detta arbete så undersöktes först de rådande standarderna inom området, detta för att välja ut den mest lämpliga standarden för detta arbete beträffande kriterier och viktiga beräkningsfaktorer. De viktigaste provtagningarna och analyserna som dessa standarder berörde gällde bränsle, aska och rökgaser. För att genomföra alla provtagningar skapades ett provtagningsschema. Provtagningarna genomfördes på båda pannorna vid två olika provtagningstillfällen, därefter skickades proverna på analys och pannverkningsgraden kunde sedan beräknas.Resultatet som detta arbete resulterade i är att panna 6 har något högre pannverkningsgrad än panna 7, 89,3 respektive 82,8 %. Detta medför att förlustfaktorerna står för 10,7 samt 17,2 % för panna 6 respektive panna 7, där den överlägset största förlustfaktorn är rökgasförlusterna. Denna förlustfaktor beror till stor del på rökgasernas temperatur och fukthalt. Rökgasförlusterna uppgår till 9,5 samt 16,3 % på panna 6 respektive panna 7. Därefter i storleksordningen kommer askförlusterna för panna 6 (0,8 %) och värmeförlusterna för panna 7 (0,5 %). Både värmeförlusterna och askförlusterna för panna 6 respektive panna 7 uppgår till en förlustfaktor på 0,3 %. Den minsta förlustfaktorn är oförbränt i gasfas (CO) som ligger mellan 0–0,1 % för panna 6 och panna 7, detta tyder på låga halter av kolmonoxid och oförbränt i rökgaserna.De effektiviseringsförslag som detta arbete ledde fram till var att minska fukthalten och temperaturen på de utgående rökgaserna, detta genom att installera en rökgaskondenseringsanläggning som sänker rökgastemperaturen ytterligare och kondenserar ut mer fukt från rökgaserna. Detta realiseras genom att sänka kondensattemperaturen i rökgaskondenseringsanläggningen antingen genom lägre returledningstemperatur på fjärrvärmen som värmeväxlas mot kondensatet eller via en värmepump placerad mellan fjärrvärmereturen och kondensatet som arbetar med en lägre drifttemperatur än fjärrvärmen. Ett annat effektiviseringsförslag är att förbättra bränslehanteringen genom att torka bränslet innan de matas in i pannan. Slutligen skulle också en mer frekvent uppföljning av bränsleparametrar såsom värmevärde vara ett möjligt effektiviseringsförslag. Alla dessa förslag kräver dessvärre en ekonomisk och tekniskt utredning för att avgöra om dessa effektiviseringsförslag är ekonomiskt försvarbara samt tekniskt genomförbara. / On behalf of Umeå Energi AB, two of their grate fired heating boilers (boiler 6 and 7) was evaluated with respect to boiler efficiency. Currently these boiler efficiency calculations is carried out monthly by the input-output method. This calculation method is unfortunately rather unreliable, which means that a more exact examination of the boiler efficiency is required. For this reason, the boiler efficiency was calculated using the energy balance method, which gives more reliable results and also evaluates the boiler losses. Boiler efficiency was calculated and analysed with respect to the boiler losses at approximately the same useful effect for both the boilers.To perform this work the leading standards in the field were examined, which was done in order to evaluate the most appropriate standard with regard to criteria and important calculation factors. The most important samples and analyses that these standards was concerned with was fuel, ash and flue gas. To conduct all sampling, a sampling plan was created. All samplings was performed on both boilers at two sampling occasions, the samples were then sent for analysis and the boiler efficiency could then be calculated.The result from this work shows that boiler 6 has slightly higher boiler efficiency than boiler 7, 89.3 and 82.8% respectively. As a result, the boiler losses total up to 10.7 and 17.2% for boiler 6 and 7 respectively, where the flue gas losses constitutes the largest losses. The flue gas losses depends largely on the temperature of the flue gases and the moisture content. Flue gas losses sums up to 9.5 and 16.3% on boiler 6 and 7 respectively. The second largest boiler loss is ash losses on boiler 6 which sums up to 0.8% and heat losses on boiler 7 which sums up to 0.5%. The heat losses on boiler 6 and the ash losses on boiler 7 both sums up to a boiler loss of 0.3 %. The smallest loss factor is unburned in gas phase (CO) and is between 0–0.1% for boiler 6 and boiler 7, this suggests low levels of carbon monoxide and unburned in flue gases.The efficiency proposals this work resulted in was to reduce the moisture content and temperature of the outgoing flue gases, this by installing a flue gas condenser, which lowers the temperature further and condenses out more moisture from the flue gases. This is realized by reducing the flue gas condensate temperature either through lowering district heating return temperature which exchange heat with the flue gas condensate or through a heat pump that is placed between the district heating return and flue gas condensate which operates at a lower temperature than the district heating. Another efficiency proposals is to improve the fuel handling by drying the fuel before being fed into the furnace. Finally, also a more frequent follow up of the fuel parameters such as calorific value would be a possible efficiency proposal. All of these proposals require unfortunately economic and technical investigation to determine whether these efficiency proposals are economically viable and technically feasible.
222

Validation of the WAM-model over the Baltic Sea

Berg, Caroline January 2008 (has links)
<p>In order to understand how waves influence the exchange of momentum, latent heat and other parameters, between the ocean surface and the atmosphere, one can use models. A coupling between a wave model and an atmospheric regional climate model, for the Baltic Sea, will be performed at the Meteorology Institute in Uppsala University. The wave model is a state of the art, third generation wave model called WAM.</p><p>The new version of the WAM model (cycle 4) needs to be validated. The aim of this thesis is to perform this validation and also to investigate what meteorological forcing one should use to achieve best results. Two different types of forcing are analyzed, ERA40 reanalysis and the RCA climate model. In order to do this, observations from six different buoys in the Baltic Sea will be compared with the model output from WAM. The parameters that will be compared in this study are significant wave height, direction and peak period.</p><p>A consistent phenomenon for all the buoys is a slightly overestimation by the model of what the rate of this increases with increasing wave height. If one compares the model output when WAM are forced with the RCA climate model and when it is forced with ERA40 reanalysis, the differences between them are notable but not large. ERA40 is slightly better.</p><p>Significant wave height is quite good and gives a reasonably result. Some buoys and periods are better and some are worse. There are some differences for the significant wave height between the east coast and the west coast of Sweden, when forcing the model with RCA. It is slightly better on the west coast. On the contrary, the results from ERA40 are very coherent. The quality of the hindcast for the direction and the peak period, in contrast to the significant wave height, is not that good. The results are not bad, but it only gives a rough picture of the sea state.</p>
223

Positionnement optimal de l'activité physique pour profiter de l'effet anorexigène

Albert, Marie-Hélène 08 1900 (has links)
La balance énergétique (dépense énergétique et ingestion calorique) est au centre du contrôle de la masse corporelle. L’activité physique peut par ailleurs réduire l’appétit et l’ingestion calorique, un phénomène qu’on appelle aussi l’effet anorexigène de l’activité physique. Cependant, l’hormone orexigénique, liée à une diminution de l’appétit, diminue pendant l’exercice pour remonter rapidement après l’effort. Le but de ce mémoire était de déterminer si l’ingestion calorique est réduite quand l’exercice précède immédiatement le repas comparativement à une condition où il y a une pause entre l’exercice et le repas. Pour ce faire, douze garçons non obèses (15-20 ans) ont pris part à l’étude. Chaque participant était évalué individuellement pour les deux tâches suivantes, et ce, dans un ordre aléatoire : 1) Ex = 30 minutes d’exercice (70% VO2max) suivi immédiatement par un buffet à volonté à midi; 2) Expause = 30 minutes d’exercice (70% VO2max) suivi d’une pause de 135 minutes et d’un buffet à volonté à midi. Les visites étaient précédées par un déjeuner standard et complétées avec une collation à volonté durant l’après-midi et un souper type buffet à volonté pour souper. Alors que les résultats ont révélé que la faim était similaire en tout temps, l’ingestion calorique au diner était plus basse pour la condition Ex que pour la condition Expause (5 072 vs 5 718 kJ; p < 0,05). Aucune différence significative n’a été notée pour la collation de l’après-midi et le souper. Chose intéressante, l’ingestion calorique des lipides était plus basse au diner avec une ingestion de 1 604 kJ pour la condition Ex versus 2 085 kJ pour la condition Expause (p < 0,05). Cette étude est la première à investiguer l’effet du positionnement optimal de l’activité physique pour réduire l’ingestion calorique et elle révèle qu’être actif physiquement juste avant le repas joue un rôle sur la diminution de l’ingestion calorique indépendamment des sensations d’appétit. L’absence d’une compensation durant le reste de la journée suggère de plus qu’une balance énergétique négative, incluant une réduction de la consommation de lipides, peut être plus facilement atteinte en positionnant l’activité physique juste avant un repas. / Energy balance (energy expenditure and energy intake) is the central of body weight control. Interestingly, physical activity can suppress appetite and energy intake, a phenomenon also called exercise-induced anorexia. However, orexigenic hormone, which decrease appetite, decreases during exercise to rapidly increase following the effort. Until now, no study has examined the optimal timing of physical activity to maximize this anorexigenic effect and this was the goal of the present thesis. Concretely, this project aimed to determine if energy intake is reduced when exercise immediately precedes the meal compared to a condition in which a pause is present between the exercise and the meal. To do so, twelve non-obese boys (15-20 years old) took part in the study. Each subject was individually evaluated performing the two following tasks in a randomized order: 1) Ex=30-minute exercise bout (70% VO2max) followed immediately by an ad libitum buffet at noon; 2) Expause=30-minute exercise bout (70% VO2max) followed by a 135-minute waiting period and an ad libitum buffet at noon. The visits were preceded by a standardized breakfast and completed with an ad libitum snack in the afternoon and a buffet-type dinner. While results shown that hunger was similar at all times, energy intake at lunch was lower for the Ex condition than for the Expause condition (5,072 vs. 5,718 kJ; p<0.05). No significant difference was noted for the afternoon snack and dinner. Interestingly, caloric intake of fat was lower at lunch, with 1,604 kJ for the Ex condition versus 2,085 kJ for the Ex pause condition (p<0.05). This study is the first to investigate the effect of the timing of physical activity on energy intake, and it reveals that being physically active right before a meal does play a role in energy intake reduction independently of pre-meal appetite sensations. Also, the absence of compensation during the rest of the day suggests that a negative energy balance, including a reduction in lipid consumption, could be more easily obtained by positioning physical activity before a meal.
224

Three-dimensional modeling of radiative and convective exchanges in the urban atmosphere / Modélisation tri-dimensionnelle des échanges radiatifs et convectifs dans l’atmosphère urbaine

Qu, Yongfeng 18 November 2011 (has links)
Dans de nombreuses études micrométéorologiques, les modèles numériques prenant en compte les bâtiments considèrent généralement l'atmosphère comme neutre. Néanmoins, les transferts radiatifs urbains jouent un rôle important en raison de leur influence sur le bilan énergétique. Afin de prendre en compte le rayonnement atmosphérique et les effets thermiques des bâtiments dans les simulations de l'écoulement atmosphérique et la dispersion des polluants en milieux urbains, nous avons développé un modèle de rayonnement atmosphérique tridimensionnel (3D), dans le module atmosphérique du code de mécanique des fluides Code_Saturne. Le schéma radiatif a été précédemment validé avec des cas idéalisés, en utilisant dans un premier temps, un champ constant de vent 3D. Dans ce travail, le couplage des schémas radiatifs et thermiques avec le modèle dynamique est évalué. L'objectif de la première partie est de valider le couplage complet avec les mesures de la campagne de mesure américaine ‘Mock Urban Setting Test' (MUST) sur des géométries simples. La deuxième partie traite deux approches différentes pour modéliser les échanges radiatifs en milieu urbain avec une comparaison entre Code_Saturne et SOLENE. La troisième partie utilise le couplage complet pour montrer l'apport du modèle de transfert radiatif sur l'écoulement de l'air dans des conditions de faible vitesse du vent dans une canopée 3D. Dans la dernière partie, nous utilisons le couplage dynamique-radiatif pour simuler un environnement urbain réel et valider le modèle avec les données expérimentales de la campagne ‘Canopy and Aerosol Particle Interactions in Toulouse Urban Layer' (CAPITOUL) / In many micrometeorological studies, building resolving models usually assumea neutral atmosphere. Nevertheless, urban radiative transfers play an important role because of their influence on the energy budget. In order to take into account atmospheric radiation and the thermal effects of the buildings in simulations of atmospheric flow and pollutant dispersion in urban areas, we have developed a three-dimensional (3D) atmospheric radiative scheme, in the atmospheric module of the Computational Fluid Dynamics model Code_Saturne. The radiative scheme was previously validated with idealized cases, using as a first step, a constant 3D wind field. In this work, the full coupling of the radiative and thermal schemes with the dynamical model is evaluated. The aim of the first part is to validate the full coupling with the measurements of the simple geometry from the ‘Mock Urban Setting Test' (MUST) experiment. The second part discusses two different approaches to model the radiative exchanges in urban area with a comparison between Code_Saturne and SOLENE. The third part applies the full coupling scheme to show the contribution of the radiative transfer model on the airflow pattern in low wind speed conditions in a 3D urban canopy. In the last part we use the radiative-dynamics coupling to simulate a real urban environment and validate the modeling approach with field measurements from the ‘Canopy and Aerosol Particle Interactions in Toulouse Urban Layer' (CAPITOUL)
225

Observation et modélisation des échanges d’énergie et de masse de jeunes peuplements forestiers du Sud-Ouest de la France / Observation and modelling of energy and mass exchanges in young forest stands in south-western France

Moreaux, Virginie 26 March 2012 (has links)
Ce travail de thèse a porté sur la prise en compte de la phase juvénile des peuplements forestiers du Sud-Ouest de la France dans la caractérisation des échanges sol-végétation-atmosphère. L’étude s’est focalisée sur des structures de peuplements contrastées de jeunes peuplements de Pins maritimes et d’Eucalyptus. La première partie de ces recherches a consisté à étudier de façon expérimentale les échanges de masse et d’énergie de jeunes plantations d’Eucalyptus et de Pins maritimes du Sud-Ouest. Trois sites instrumentés pour la détermination en continu des échanges de CO2 et H2O, bilan d’énergie, flux de sève et de croissance et production des arbres ont été suivis durant deux années marquées par des épisodes répétés de sécheresse. Le comportement des essences présentes a été comparé ainsi que les effets de l’environnement et des pratiques culturales sur le fonctionnement de ces écosystèmes. Les bilans annuels d’eau, de carbone et la croissance et la production des trois peuplements ont été établis et comparés. A partir de ces mesures enrichies par des données déjà disponibles et en se basant sur le modèle de production forestière et de transfert sol-végétation-atmosphère GRAECO (INRA-EPHYSE), modèle mécaniste biophysique monodimensionnel, la deuxième partie a consisté à développer une nouvelle évolution de ce modèle pour l’adapter au cas des systèmes de culture de biomasse forestière à croissance rapide. L’approche proposée en couplant ce modèle avec le modèle MAESTRA (Medlyn 2004) a permis de dépasser les hypothèses d’homogénéités verticale et horizontale du couvert pour rendre compte de l’effet de la structure en trois dimensions de peuplements jeunes à couronnes disjointes et sous-étage développé sur les transferts radiatifs, de CO2 et vapeur d’eau. De plus, le modèle a été complété par trois nouveaux modules décrivant respectivement la dynamique du carbone du sol (Roth-C) et la croissance et fonctionnement du sous-étage et du taillis. Il a été évalué sur les données existantes couvrant différents sites et séries temporelles et incluant une série d’interventions de type labour, désouchage, disquage superficiel, semis, dépressages, éclaircies et recépées. Enfin, ce modèle a été implémenté sur un jeu de données décrivant le climat local sous le forçage du scénario climatique A2 régionalisé sur un point de la grille SAFRAN de Météo-France pour trois itinéraires sylvicoles de Pin maritime et Eucalyptus, afin d’évaluer, à titre exploratoire, les potentialités de productivité de ces itinéraires. / In this thesis, the juvenile phase of forest stands of southwestern France was studied in order to characterise soil-vegetation-atmosphere exchanges. The study focused on contrasted structures of young pines and Eucalyptus stands. The first part of this research was to study experimentally the mass and energy exchanges of young plantations of pines and Eucalyptus growing in southwestern France. Continuous measurements of CO2 and H2O fluxes, energy balance, sapflow and tree growth and production were carried out for two years, a period marked by repeated episodes of drought. The behavior of these species was compared, as well as the effects of the environment and cultural practices on these ecosystems. The annual water and carbon balances, growth and production of the three stands were established and compared. These measurements were enriched by data already available and were based on the 1D-mechanistic model of forest production and soil-vegetation-atmosphere transfer GRAECO (INRA-EPHYSE). The second part of the thesis focused on developing a new version of the model to be applied to crop systems for fast-growing forest biomass. By coupling this evolution of the model with the 3D-model MAESTRA (Medlyn 2004), the assumptions of vertical and horizontal homogeneities in the canopy can be exceeded thus accounting for the effect of the three-dimensional structure on the radiative, CO2 and water vapor transfers in young stands, where crowns are separate and the understorey is well-developed. In addition, the model was supplemented by three new modules describing the dynamics of soil carbon (Roth-C) and the growth and functioning of the understory and coppice. It was evaluated on existing data covering different sites and time series and including a series of forest practices, such as plowing, stump removal, superficial disking, seeding, early thinning, thinnings and cutting down close to the ground. Finally, as an exploratory work, this model has been implemented on a data set describing the local climate forced by the A2 climate scenario which was regionalized on a SAFRAN grid point (‘Météo-France’) for three forest itineraries of maritime pine and Eucalyptus, in order to assess the potential productivity of these systems.
226

Evaluation of surface energy balance models for mapping evapotranspiration using very high resolution airborne remote sensing data

Paul, George January 1900 (has links)
Doctor of Philosophy / Department of Agronomy / P.V. Vara Prasad / Agriculture is the largest (90%) consumer of all fresh water in the world. The consumptive use of water by vegetation represented by the process evapotranspiration (ET) has a vital role in the dynamics of water, carbon and energy fluxes of the biosphere. Consequently, mapping ET is essential for making water a sustainable resource and also for monitoring ecosystem response to water stress and changing climate. Over the past three decades, numerous thermal remote sensing based ET mapping algorithms were developed and these have brought a significant theoretical and technical advancement in the spatial modeling of ET. Though these algorithms provided a robust, economical, and efficient tool for ET estimations at field and regional scales, yet the uncertainties in flux estimations were large, making evaluation a difficult task. The main objective of this study was to evaluate and improve the performance of widely used remote sensing based energy balance models, namely: the Surface Energy Balance Algorithm for Land (SEBAL), Mapping Evapotranspiration at high Resolution and with Internalized Calibration (METRIC), and Surface Energy Balance System (SEBS). Data used in this study was collected as part of a multi-disciplinary and multi-institutional field campaign BEAREX (Bushland Evapotranspiration and Agricultural Remote Sensing Experiment) that was conducted during 2007 and 2008 summer cropping seasons at the USDA-ARS Conservation and Production Research Laboratory (CPRL) in Bushland, Texas. Seventeen high resolution remote sensing images taken from multispectral sensors onboard aircraft and field measurements of the agro-meteorological variables from the campaign were used for model evaluation and improvement. Overall relative error measured in terms of mean absolute percent difference (MAPD) for instantaneous ET (mm h[superscript]-[superscript]1) were 22.7%, 23.2%, and 12.6% for SEBAL, METRIC, and SEBS, respectively. SEBAL and METRIC performances for irrigated fields representing higher ET with limited or no water stress and complete ground cover surfaces were markedly better than that for dryland fields representing lesser ET and greater soil water deficits with sparser vegetation cover. SEBS algorithm performed equally well for both irrigated and dryland conditions but required accurate air temperature data. Overall, this study provides new insights into the performance of three widely used thermal remote sensing based algorithms for estimating ET and proposed modifications to improve the accuracy of estimated ET for efficient management of water resources.
227

Modelagem do balanço energético na alimentação suplementar para bovinos. / Energy balance modelling in cattle supplementary feeding.

Romanelli, Thiago Liborio 16 January 2003 (has links)
A necessidade em se produzir alimentos para atender a demanda crescente, vem se constituindo em um dos principais problemas da humanidade. Desde o primeiro choque do petróleo, em 1973, há preocupação com o consumo de energia, devido à escassez dos recursos energéticos, que ameaça a sustentabilidade dos sistemas de produção atuais. O balanço energético é de fundamental importância para a determinação da eficiência no aproveitamento da energia de um sistema de produção agrícola sendo determinado através da quantificação dos fluxos de entrada e saída de energia no sistema. O Brasil é o segundo maior produtor mundial de carne bovina e o sexto de leite. Devido à importância econômica da pecuária no país, há uma grande preocupação com a produção de alimentação suplementar para ser fornecida aos animais durante o período seco, sendo um dos métodos mais utilizados para esse fim, a silagem de milho. Além dos métodos tradicionais de produção de alimentação suplementar como a ensilagem e a fenação, surgiram técnicas mais modernas como a silagem emurchecida, utilizada principalmente com gramíneas, que tem o seu sistema de produção muito similar ao do feno,porém apresenta menor tempo de secagem, prevenindo perdas quali e quantitativas no material a ser recolhido.O trabalho proposto avaliou a eficiência energética de dois diferentes sistemas de produção de alimentos suplementares para bovinos, identificando as variáveis críticas e propondo cenários alternativos. A silagem de milho apresentou balanço energético bruto de 14,08, ou seja produziu 15,08 vezes o que consumiu, já a silagem emurchecida de Tifton 85 apresentou balanço energético bruto de - 0,98, consumindo 1,98 vezes o que produziu. Considerando a energia de saída efetivamente disponível ao gado, devido ao teor de NDT da cultura, o balanço energético é de 9,12 e -0,99, respectivamente. A maior demanda da produção da silagem de milho foram a adubação de cobertura e a semeadura-adubação, com 49,34 e 24,06%, respectivamente. Na produção da silagem emurchecida a irrigação demandou 99,72% do total da energia de entrada. O balanço energético diário, que visa considerar a ocupação do solo pelo sistema de produção, foi de 0,087 e - 0,022 para o milho e o Tifton 85, respectivamente. Os mesmos parâmetros considerando a energia de saída disponível ao rebanho, via teor de NDT, são 0,057 e -0,022, respectivamente. / The need in producing food to supply the increasing demand has been one of the most important problems of mankind. Since the first oil chock, in 1973, there is worry about the energy consumption, because of the lack of energy sources, which threatens the sustainability of the present-day production systems. The energy balance has a important role to evaluate how efficient the energy use by a production system is. And it is determined through the quantification of the income and outcome energy flows. Brazil is the second biggest cattle meat producer and the sixth milk producer. Because of the economic importance of cattle raising in Brazil, there is a great worry about supplementary food to be supplied to cattle during the dry season. To reach this goal, maize silage is one of the most used methods. In addition to the traditional methods, like silage and hay, more modern techniques were created such as haylage, which is used mainly with grasses and has its production system too similar to the hay’s. But haylage requires shorter time to dry, avoiding losses in quantity and quality in the vegetal material that will be collected. The present work evaluated the energetic efficiency in two different production systems of supplementary food to cattle, identifying critical variables and suggesting alternative scenarios. Maize silage presented a gross energybalance of 14.08, what means a outcome energy 15.08 times higher than the income one. haylage presented a gross energy balance of - 0.98, what means a income energy 1.98 times higher than the outcome one. When the really available energy to cattle was considered through the TDN levels, maize silage and haylage presented energy balances of 9.12 and -0.99, respectively. The highest energy demand in the maize silage production was the fertilizer spreading during the seeding and field cultivation, responsible for 49.34% and 24.06%, respectively. In the haylage production system irrigation was the most demanding operation since it was responsible for 99.72% of the total demanded energy. The daily energy balance, which aims to consider the soil occupation period, was 0.087 to maize silage, and -0.022 to haylage (Tifton 85). The same parameters regarding the effective energy available to cattle, via TDN, were 0.057 and -0.022, respectively.
228

Modelagem do balanço de energia do dossel da cultura do pimentão em casa de vegetação. / Canopy energy balance modeling of sweet pepper cultivated in greenhouse.

Atarassi, Roberto Terumi 19 January 2005 (has links)
Dentre os elementos em um sistema de produção em casa de vegetação, o dossel da cultura é o que mais afeta o microclima interno, sendo de grande importância o entendimento dos seus processos de troca de energia. Dada à complexidade da interação entre os vários elementos, a modelagem mostra-se como uma importante ferramenta para a pesquisa em ambientes protegidos, porém muito pouco utilizado no Brasil. O objetivo do presente trabalho foi o desenvolvimento de um modelo de simulação para estimativa dos componentes do balanço de energia do dossel da cultura do pimentão em casa de vegetação e sua calibração e teste com dados de um experimento de campo. Foi desenvolvido um modelo em equilíbrio dinâmico composto de quatro submodelos: fluxo de calor latente (&#955;E), fluxo de calor sensível (H), balanço de ondas curtas (BOC) e balanço de ondas longas (BOL). Os submodelos para &#955;E e H foram baseados em teorias de transferência de massa e calor por convecção mista associada a uma equação de estimativa da resistência estomática a partir de medidas climáticas. Os submodelos de BOC e BOL levaram em consideração a disposição em linhas da cultura, a cobertura parcial do dossel e o Índice de Área Foliar (IAF). O modelo foi implementado em planilha eletrônica MICROSOFT EXCEL 2000 e resolvido numericamente através de uma rotina escrita em linguagem VBA (Visual Basic para Aplicativos). O modelo foi calibrado e testado com experimento em casa de vegetação em arco com 17,5 x 6,4m, pé-direito de 3m e altura de arco de 1,2m, localizada no município de Piracicaba - SP, no Campus da Escola Superior de Agricultura "Luiz de Queiroz"/USP, cultivada com pimentão amarelo, em linha simples no espaçamento de 1,2m x 0,5m. Foram feitas medidas de ranspiração com lisímetro com células de carga, radiação global, difusa e fotossinteticamente ativa, velocidade do vento, temperatura e pressão atual de vapor e temperatura do dossel. Também se tomaram medidas da cultura como IAF, altura e diâmetro de copa. A partir dos levantamentos, o modelo foi calibrado e testado. O modelo não estimou de forma precisa os componentes do balanço de energia, mas foi capaz de acompanhar a variação dos valores reais levantados em experimento, ainda que em magnitudes diferentes, indicando a necessidade de uma calibração mais adequada, em especial dos coeficientes de extinção do dossel para radiação difusa e direta. A modelagem permitiu verificar a limitação de algumas abordagens encontradas em literatura e utilizadas neste trabalho, como na determinação das resistências aerodinâmica e estomática. / In a greenhouse production system, the canopy of culture is the main element that modifies the internal microclimate. Its comprehension is very important to understand the energy exchange process. Due to the complexity interaction among several elements, the modeling represents an important tool for research in protected environments, but little used in Brazil. The aim of the present work was to develop a simulation model for estimating the components of canopy energy balance of sweet pepper crop cultivated in greenhouse and its calibration and test with experimental data. It was developed a steady-state model divided in four submodels: latent heat flux (&#955;E), sensible heat flux (H), short wave balance (BOC) and long wave balance (BOL). The &#955;E and H submodels were based on the mixed convection mass and heat transfer theory, associated with equation to leaf stomatal resistance estimation using climatic data. The BOC and BOL submodels considered the row orientation of crop, partial cover of soil and leaf area index (IAF). The model was implemented in a Microsoft EXCEL 2000 and solved numerically with routine developed in VBA language (Visual Basic for Application) The model was calibrated and tested with experimental data from a greenhouse 17,5m long by 6,4m width, 3,0m height, localized in Piracicaba City, São Paulo, Brazil, in experimental area of "LUIZ DE QUEIROZ" College Of Agriculture - São Paulo University (USP), cultivated with sweet pepper crop, in single row, spaced in 1,2m x 0,5m. It was taken measurements of transpiration from load cells weighting lysimeter, global, diffuse and PAR radiation, wind velocity, temperature and actual vapor pressure and canopy temperature. Also was taken measurements of leaf area index, height and diameter of plant. The model was test after calibration with experimental data. The model didn’t estimate precisely the components of energy balance, but it was capable to follow the variation of measured data in different proportion and indicating the necessity of better calibration, especially concerned with extinction coefficients of the canopy. The modeling allowed verifying approach limitations founded in literature and used in present model, like the determination of aerodynamic and stomatal resistances.
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A relação entre ilha de calor urbana, o uso e cobertura do solo e o balanço de energia no município de São Paulo: avaliação do campo térmico nos parques públicos de lazer / The relationship between the urban heat island, use and land cover and energy balance in São Paulo: evaluation of thermal field of public leisure parks

Barros, Hugo Rogério de 03 June 2016 (has links)
A Ilha de Calor Urbana no município e Região Metropolitana de São Paulo foi estudada por uma série de autores da Geografia e Meteorologia através da aplicação de metodologias de estudos empíricos na avaliação do fenômeno. A vigente pesquisa apresenta uma nova metodologia na avaliação do campo térmico urbano e o conjunto de variáveis climáticas e antrópicas que o condicionam. Para tal foi realizado o seguinte teste de hipótese: a dinâmica territorial da Ilha de Calor Urbana corresponde às interações entre as condições sinóticas, uso e cobertura do solo e balanço de energia. Além desta, dentre os diversos objetivos específicos, o estudo contou com a avaliação do campo térmico dos parques públicos de lazer. Para tal foram utilizados os métodos descritivo, seguido do comparativo e análise integrada descritiva, aliados a uma simbiose entre aplicações de técnicas de sensoriamento remoto e geoprocessamento. Um total de nove imagens do satélite Landsat-5 sensor TM no período de 2007 a 2011 foram utilizadas na geração de imagens termais, posteriormente estas foram vetorizadas e sobrepostas a padrões oficiais de uso do solo, também foram adotados índice de vegetação, fotografias áreas, cartas e boletins sinóticos e dados de campo referentes à temperatura do ar, umidade relativa, precipitação, direção e velocidade do vento, evaporação e radiação solar global. O modelo SEBAL (Surface Energy Balance Algorithms for Land) foi aplicado a três imagens do mapeador temático Landsat-5 de diferentes datas, através do mesmo foram gerados mapas de albedo da superfície, saldo de radiação à superfície, fluxo de calor sensível e latente. Os resultados demostraram a veracidade da hipótese, a conformação e dinâmica territorial da Ilha de Calor Urbana corresponderam a diferentes condições de tempos sinóticos, os quais determinaram o transporte de umidade do oceano para atmosfera continental e por seguinte transformaram o balanço de energia local. Foram verificados três diferentes padrões territoriais, em todos eles os padrões de uso do solo ligados a comércio e serviços, armazéns e indústrias que apresentaram índice de biomassa vegetal igual zero, obtiveram a melhor correlação espacial com o fenômeno. O cenário chamou atenção para a preservação e expansão do arboreto urbano, parques e unidades de conservação, visto que estes demonstraram ser a fonte para redução da temperatura da superfície urbana. / The Urban heat island in the city and metropolitan region of São Paulo has been studied by several authors in the areas of geography and Meteorology through the application of methodologies of empirical studies on the evaluation of the phenomenon. Our research presents a new methodology in the evaluation of the urban thermal field and the set of climatic and anthropogenic variables that influence it. To this end, the following hypothesis testing was conducted: the territorial dynamics of the urban heat island corresponds to the interactions between synoptic conditions, use and coverage of the soil and energy balance. Additionally, among several other specific objectives, the study was also preoccupied with the evaluation of the thermal field of public parks. For such purpose we applied the descriptive method, followed by the comparative method and descriptive integrated analysis, combined with a symbiosis between applications of remote sensing and GIS techniques. A total of nine satellite images Landsat-5 TM sensor in the period from 2007 to 2011 were used on thermal imaging, these were later vectorized and superimposed on official standards of land use. Other than that, vegetation index, air photographs, letters and synoptic bulletins and field data related to air temperature, relative humidity, precipitation, wind direction and speed, global solar radiation and evaporation were also adopted. The model SEBAL (Surface Energy Balance Algorithms for Land) was applied to three thematic mapper images Landsat-5 from different dates; through these images were generated albedo maps from the surface, the surface radiation balance, sensible and latent heat flux. The results proved the hypothesis true, the conformation and territorial dynamics of the urban heat island corresponded to different conditions of synoptic climates, which determined the humidity transportation from the ocean into continental atmosphere and, consequently, transformed the balance of local energy. Three different territorial patterns were investigated; in all of them the land use patterns linked to trade and services, warehouses and industries that showed the index of plant biomass equal zero obtained the best spatial correlation with the phenomenon. The scenario drew attention to the preservation and expansion of the urban arboretum, parks and protected areas since these proved to be the source for the development of thermal environmental urban quality.
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Desempenho de uma enfardadora prismática no recolhimento de palhiço / Prismatic baling performance on sugar cane residue collect

Mello, Arthur Miola de 21 September 2009 (has links)
Um dos fatores que ainda retarda o uso do palhiço remanescente da colheita mecanizada para cogeração de energia é a falta de conhecimento de processos ou sistemas que viabilizem a retirada e transporte desse material até as unidades de cogeração. O objetivo desse trabalho foi estudar os desempenhos técnico, econômico e energético de uma enfardadora, em diferentes condições de distribuição de palhiço na superfície, buscando viabilizar o recolhimento do palhiço remanescente da colheita mecanizada. O ensaio foi realizado na Usina Iracema, município de Iracemápolis-SP, em área de cana-de-açúcar, colhida mecanicamente. A área foi dividida em três subáreas., com cinco repetições de 15 fardos cada. Os tratamentos utilizados foram: T1- palhiço in natura, sem enleiramento; T2- palhiço com enleiramento simples; T3- palhiço com enleiramento duplo. As principais avaliações foram: força na barra de tração, potência, velocidade efetiva, consumo de combustível, capacidades de produção e de campo efetivas, custos efetivos para o enfardamento, eficiência energética do enfardamento e potencial energético do palhiço recolhido. Os resultados mostraram que a demanda de força na barra para tracionar a enfardadora não mostrou diferenças entre os tratamentos e variou de 344,21 a 369,43 kgf, a demanda de potência exigida para o deslocamento do conjunto foi baixa podendo, dessa forma, reservar a maior parcela para o acionamento da TDP. Houve diferenças significativas nas velocidades operacionais, com valor de 4,9 km.h-1 no enfardamento sem enleiramento, 2,45 km.h-1 no enfardamento com leiras simples e 1,73 km.h-1 no enfardamento com enleiramento duplo. A capacidade de produção efetiva no tratamento T1 foi de 6,55 t.h-1, 8,1 t.h-1 no T2 e 5,81 t.h-1 no T3. A capacidade de campo efetiva foi de 7,75 t.ha-1 no T1; 9,2 t.ha-1 no T2 e 7,54 t.ha-1. O consumo horário de combustível no T1 foi de 7,86 l.h-1, no T2 foi de 7,48 l.h-1 e no T3 de 6,54 l.h-1. O consumo por tonelada de palhiço recolhido foi menor no tratamento T2 (0,92 l.t-1), seguido do T3 (1,13 l.t-1) e do T1 (1,20 l.t-1). O Tratamento T2 apresentou menor custo por tonelada de palhiço recolhido (7,45 R$.t-1), o custo no T1 foi de 9,33 R$.t-1 e no T3 foi de 10,49 R$.t-1. A eficiência energética da operação de enfardamento no T1 foi de 99,62%, no T2 foi de 99,71% e no T3 foi 99,64%. O potencial energético do palhiço recolhido no T1 foi 9,92 EBP.ha-1, no T2 foi 11,77 EBP.ha-1 e no T3 foi de 9,65 EBP.ha- 1. Diante dos resultados, pode concluir que: o enleiramento reduziu o teor de umidade do palhiço; a demanda de força de tração e de potência para tracionar a enfardadora foram pequenas; o sistema de recolhimento de palhiço em leiras simples apresentou melhor desempenho econômico e energético; por se tratar de uma enfardadora de baixa capacidade efetiva é inapropriada para operação em grandes áreas; considerando-se as inúmeras variáveis, intervenientes nos 3 tratamentos, entende-se que a melhor opção para o uso desta enfardadora é operação em área com enleiramento simples do palhiço. / One of the factors that still delay the use of the residue of sugar cane mechanical harvest for energy cogeneration is the lack of knowledge of processes or systems that allow the materials removal and transportation to the cogenerations place. The objective of this research was study the performances technical, economic and energetic of a bailing, in different conditions of distribution of sugar cane residue on the surface, trying to make viable the collection of the remaining mechanized harvest. The test was realized at sugar cane mill Iracema, located in Iracemápolis-SP, in an area of sugar cane, mechanically harvested. The area was divided into three sub-areas, with five replicates of 15 bales each. The treatments were: T1-sugar cane residue \"in natura\", without row; T2-sugar cane residue with simple row; T3-sugar cane residue with double row. The main evaluations were: force on traction bar, power, effective speed, fuel consumption, capacitys production and effectives field, bailings effectives costs, bailings energetic efficiency and energetic potential of the sugar cane residue bailed. The results showed that the force demand on traction bar to pull the baler showed no differences between the treatments and ranged from 344.21 to 369.43 kgf, the power demand required for the displacement the tractor and the baler was low and, thus, reserve the largest portion to operate the PTO. There were significant differences in operating speeds, with a value of 4.9 km.h-1 on baling without row, 2.45 km.h-1 on baling with simple row and 1.73 km.h-1 on baling with double row. The effective production capacity in the T1 was 6.55 t.h-1, 8.1 t.h-1 in T2 and 5.81 t.h-1 in T3. The effective field capacity was 7.75 t.ha-1 in T1, 9.2 t.ha-1 in T2 and 7.54 t.ha-1. The hourly consumption of fuel at T1 was 7.86 l.h-1 in T2 was 7.48 l.h-1 and T3 of 6.54 l.h-1. The consumption per ton of sugar cane residue collected was lower in treatment T2 (0.92 l.t-1), followed by T3 (1.13 l.t-1) and T1 (1.20 l.t-1). The treatment T2 had lower cost per ton of sugar cane residue baled (7.45.R$.t-1), the cost in T1 was 9.33 R$.t-1 and T3 was 10.49 R$.t-1. The energetic efficiency of the baling operation in T1 was 99.62% at T2 was 99.71% and 99.64% in T3. The energetic potential of the sugar cane residue baled at T1 was 9.92 EBP.ha-1 in T2 was 11.77 EBP.ha-1 and T3 was 9.65 EBP.ha-1. The results may conclude that: the rows operation reduced the sugar cane residue humidity, the demand of the traction force and power to pull the baler were small, the simple rows was the system that showed better performance and energy economic; the baler had a small effective capacity for this is inappropriate for large areas; considering the many variables that affects the treatments, understood that the best option for the use of this baler is operating in sugar cane residues areas with simple rows.

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