The thesis aims to lower the exhaust gas temperature on the coming EU6 Scania buses D7 and Otto gas and is carried out as a final part of the studies in the mechanical engineering program, KTH Stockholm. Euro 6, a new emission standard requirements for heavy duty trucks and buses, puts new demands on the amount of particulate matter and nitrogen oxides that can be emitted. This led to that Scania has developed and improved their after treatment systems. The new after treatment systems generates high exhaust temperatures, and Scania have expressed a desire to reduce these to create a safer environment around the bus.The thesis started with a thorough feasibility study, where the current exhaust systems and its components were studied. Solutions to lower exhaust temperatures were studied, both in the automotive industry and in other fields. The concepts that were developed would be analyzed through CFD simulations, why basic fluid mechanics were studied. Two different exhaust systems were to be analyzed, one with a gas engine and roof outlet and one with a diesel engine and ground outlet. A total of eight concepts were presented, in which five were determined to undergo CFD simulations.A competitor analysis was conducted in which three different diffusers from competing bus and truck manufacturers were CFD simulated.The results showed that the diffusers were superior to the other concepts. The diffuser designed in this project performed well in comparison to the diffusers from competing bus and trucks manufacturers, but it was considered to be expensive and difficult to manufacture. New diffuser designs were suggested, which are believed to have the same good qualities but cheaper to manufacture. The authors recommend Scania to perform field tests of the redesigned diffusers, and also try the ones designed by their competitors. Also, Scania should investigate how a venturi solution can be optimized. / Examensarbetet, vars mål är att sänka avgastemperaturen på Scanias bussar, är genomfört som en avslutande del av studierna på maskinkonstruktionsprogrammet, KTH Stockholm. EuroVI, en ny emissionskravsstandard för tunga fordon, ställer nya krav på hur mycket partiklar och kväveoxider som får släppas ut. Detta har resulterat i att Scania har utvecklat och förbättrat sina efterbehandlingssystem. De nya efterbehandlingssystemen ger upphov till höga avgastemperaturer, och Scania har uttryckt en önskan att sänka dessa för att skapa en säker miljö runt bussen.Examensarbetet började med en grundlig förstudie, där de aktuella avgassystemen och dess komponenter studerades. Lösningar för att sänka avgastemperaturer studerades, både inom fordonsindustrin och inom andra områden. Eftersom koncepten som togs fram skulle analyseras med CFD simuleringar, så studerades även grundläggande strömningsmekanik. Två olika avgassystem skulle analyseras, ett med en gasmotor och takutsläpp, och ett med en dieselmotor och markutsläpp. Totalt togs åtta koncept fram, varav fem ansågs intressanta för CFD simulering. Det gjordes även en konkurrentanalys, där tre olika diffusorer från konkurrerande buss- och lastbilstillverkare CFD simulerades.Resultaten visade att diffusorerna var överlägsna de andra koncepten. Diffusorn som utformats i detta projekt stod sig väl mot konkurrenternas diffusorer, men ansågs dock vara dyr och svår att tillverka. Nya designer togs fram, som anses ha samma temperatursänkande egenskaper men vara enklare att tillverka. Författarna till denna rapport rekommenderar Scania att gå vidare med fysiska tester av de förslagna diffusorerna, och att även testa konkurrenternas diffusorer. Scania bör även undersöka hur en venturilösning kan optimeras.

The dispersion model was used to study mixing levels in a full scale aeration tank. The effect of air flow rate, water flow rate and diffuser type was investigated. The peak time technique proved satisfactory in predicting the theoretical tracer response curve generated using the dispersion model. The dispersion model adequately described the longitudinal mixing that occurred in a full scale aeration tank equipped with fine and coarse bubble air diffusers. Response curves from two tanks-in-series were also obtained. / Thesis / Master of Engineering (ME)

Unter den Methoden zur Suche nach Neutrino Ereignissen in IceCube versprechen Suchen nach Teilchenschauern, sogenannten Kaskaden eine gute Energieauflösung und einen verhätlnismässig geringen atmosphärischen Untergrund. Dadurch erreichen solche Suchen eine hohe Sensitivität für einen extraterrestrischen Neutrino Fluss. Bisher beschränkte sich die Suche nach solchen Ereignissen auf solche in einer inneren Region des IceCube Detektors. Das Detektorvolumen am Rand wurde bisher benutzt um den Untergrund von einfallenden atmosphärischen Muonen zu Unterdrücken. Diese Dissertation präsentiert eine Analyse von 2 Jahren IceCube Daten und demonstriert die Möglichkeit, diese Veto Region für die Suche nach kaskadenartigen Ereignissen zu nutzen. Dadurch wird das nutzbare Detektorvolumen um « 80% vergrößert und die Statistik im hochenergetischen Bereich des Neutrino Spektrums durch das Hinzufügen von 18 Neutrino Kandidaten im Energiebereich von 34 - 578 TeV erhöht. Das Ergebnis ist in Übereinstimmung mit dem etablierten Nachweis eines extraterrestrischen Neutrino Flusses, eine reine Untergrund Hypothese kan mit 2.7 sigma verworfen werden und die Daten favorisieren einen extraterrestrischen Neutrino Fluss mit einem ungebrochen Potenzgesetz mit einem Index von γ ^ 2.50+-0.28 in guter Übereinstimmung mit bisherigen Ergebnissen von IceCube. / Among the analysis strategies used in IceCube, searches for neutrinoinduced particle showers, so called cascades, provide good energy resolution and a relative low atmospheric background. Therefore, they provide large sensitivity to the extraterrestrial neutrino flux. Previously, these searches have been constrained to neutrino interactions in a center region of the instrumented volume. The volume at the border and surrounding the detector was needed to veto the incident atmospheric muon background. This dissertation presents an analysis of two years of IceCube data and demonstrates the feasibility of using the veto region for cascade searches. This increases the usable detector volume by « 80% and improves the statistic in the high-energy tail of the neutrino spectrum by adding 18 neutrino candidates in the energy range from 34 to 576 TeV. The result is supports the established evidence for the extraterrestrial neutrino flux by rejecting the pure atmospheric background hypothesis at the 2.7 sigma level, the data prefers an extraterrestrial neutrino flux with a featureless power law with an index of γ^2.50+-0.28 well in agreement with previous IceCube results.

This doctoral thesis studies the non-uniform blade cascade for centrifugal pumps. Influence of non-uniform blade cascade is investigated on the impeller and diffuser. A non-uniform blading impeller of pumps in this doctoral thesis was examined in terms of influence on efficiency characteristic. The idea of using non-uniform blading is to obtain a flat efficiency characteristic. Then the centrifugal pump could be used on larger scale of power with achieving a sufficiently high efficiency. The work is based on experimental measurements and numerical simulations of non-uniform hydraulic pump components. Non-uniform impeller and the diffuser were newly designed for this research. A new measuring track of small submersible pumps was needed to design and build for measurements. Different pump combinations with conventional hydraulics on one working point and hydraulics with non-uniform were measured. All measurements were evaluated and characteristics of efficiency, head and power were obtained for each measured combination. Some of pump combinations (which were measured in experiment) were numerically simulated by program Ansys Fluent. Data needed to evaluate the characteristic of efficiency and specific energy were collected from each numerical simulation. A theoretical consideration concerns the influence of non-uniform blade cascade applied on diffuser. The suggestion how to decrease hydraulic losses in canals was done. The theoretical consideration how to make a flat efficiency characteristic was made.

<p>Within the gas turbine industry, turbofan engines are widely implemented to enhance engine efficiency, specific thrust, and specific fuel consumption. However, these turbofans have yet to be widely implemented into microgas turbine engines. As turbofans become implemented into smaller engines, the need to design engine intakes for high-speed mission becomes more vital. In this work, a design procedure for compact, highly diffusive engine intakes for high subsonic speed applications is set about. The aerodynamic tradeoffs between cruise and takeoff flights are discussed and methods to enhance takeoff performance without negatively impacting high-speed cruise performance is discussed. Intake performance is integrated into overall engine analysis to help guide future mission analyses. Finally, an experimental model for engine intakes is developed for application to linear wind tunnels; allowing future designers to effectively validate numerical results.<br></p> <p>A multi-objective optimization routine is performed for compact engine intakes at a Mach number of 0.9. This optimization routine yielded a family of related curves that maximize intake diffusive capability and minimize intake pressure losses. Design recommendations to create such optimal intakes are discussed in this work so that future designers do not need to perform an optimization. Due to high diffusion rate of the intake, the intake performance at takeoff suffers greatly (as measured by massflow ingestion). Methods to enhance takeoff performance, from designing a variable geometry intake, to creating slots, to sliding intake components are evaluated and ranked for future designers to get an order of magnitude understanding of the types of massflow enhancements possible. Then, off-design performance of the intake is considered: with different Mach number flights, non-axial flow conditions, various altitudes, and unsteady engine operation considered. These off-design effects are evaluated to generate an intake map across a wide engine operational envelope. This map is then inputted into an engine model to generate a performance map of an engine; which allows for mission planning analysis. Finally, various methods to replicate intake flow physics in a linear wind tunnel are considered. It is shown that replicating diffuser curvature in a linear wind tunnel allows for best replication of flow physics. Additionally, a method to non-dimesnsionalize intake performance for application to a wind tunnel is developed. </p> <p>This work can be utilized by future engine intake designers in a variety of ways. The results shown here can help guide future designers create highly compact diffuser technology, capable of operating across a wide breadth of conditions. Methods to assess intake performance effects on overall engine performance are demonstrated; and an experimental approach to intake analysis is developed.</p>

Novel integrated ozone contactor design and optimization tools which consist of an instrument that measures ozone decay kinetics, a program that performs predictive simulation, and an experimental method to examine mixing characteristics within the ozone contactor, were developed in this study. A multi-channel stopped-flow reactor (MC-SFR) is an instrument that performs automatic, real-time, and continuous analysis of ozone decay kinetics in natural waters. Ozone Contactor Model (OCM) is the software to simulate the performance of full-scale ozone bubble-diffuser contactors in support of current and future regulations regarding pathogen and bromate control in drinking water. The MC-SFR and OCM developed in this study were further applied to simulate Cryptosporidium parvum oocyst log inactivation and bromate formation in Linnwood Water Plant Ozone Facility (LWPOF) at Milwaukee Water Works, Milwaukee, WI and model predictions were verified with experimental results. Three dimensional laser induced fluorescence(3DLIF) allowed real time characterization of mixing conditions in a physical model ozone contactors by capturing fluorescence image emitted from a laser dye (i.e. Rhodamine 6G) using a high speed CCD camera. 3DLIF system was applied to analyze the hydrodynamics of two representative types of ozone contactor: direct discharge side-stream venturi injector (SVI) and multi-chambered fine bubble diffuser (FBD). Experimental results verified the presence of circulative swirling related for low dispersion for SVI reactor and the existence of non-ideal flow including short circuiting and internal recirculation in FBD reactor. Finally, integrated tools were applied to the design of a new ozone contactor under planning stage to assess current design and to recommend the improvement.

Biotreatment for air pollution control can generally be categorized as biofilter, bioscrubbing and biotrickling filter systems. Generally, biotreatments could be effective and more economical treatment for containment waste gas if designed and operated properly. A two stage down-flow biofilter (2.18 m in height and 0.4 m¡Ñ0.4 m in cross-sectional area) was constructed to develop a biofilter packed only with fern chips for the removal of air-borne propylene glycol monomethyl ether acetate (PGMEA). Both stages were packed with fern chips of 0.30 m in height and 0.40 m ¡Ñ0.40 m in cross section. Fern chips could avoid the shortcomings of traditional media, such as compaction, drying, and breakdown, which lead to the performance failure of the biofilters. In addition, the fern chip medium has the following merits: (1) simplicity in composition, (2) low pressure drop for gas flow (< 20 mmH2O m-1), (3) simple in humidification, nutrient addition, pH control, and metabolite removal, (4) economical (USD$ 174 ¡V 385 m-3), and (5) low weight (wet basis around 290 kg m-3). Results indicate that with operation conditions of media moisture content controlled in the range of 50 ¡V 74%, media pH of 6.5 ¡V 8.3, EBRT (empty bed retention time) of 0.27 ¡V 0.4 min, influent PGMEA concentrations of 100 to 750 mg m-3, volumetric organic loading of < 170 g m-3 h-1, and nutrition rates of Urea-N 66.0 g m-3.day-1, KH2PO4-P 13.3 g m-3.day-1 and milk powder 1.0 g m-3 day-1, the fern-chip packed biofilter could achieve an overall PGMEA removal efficacy of around 94%. Instant milk powder or liquid milk was essential to the good and stable performance of the biofilter for PGMEA removal. An activated sludge aeration basin (20 cm i.d., 140 cm height) equipped with either a coarse air diffuser (a plastic pipe perforated with 56 orifices of 2 mm in diameter) or a fine diffuser (porous plastic type with 100-micrometer pores) was utilized to treat an air-borne hydrophobic VOC (toluene, 700 ¡V 800 mg m-3). The purposes of this study were to test the influences of both MLSS and diffuser type on the VOC removal efficiency. Results show that higher MLSS (mixed liquor suspended solids) such as 10,000 ¡V 40,000 mg L-1 in the mixed liquor did not enhance greatly the transfer and removal of the introduced toluene. Instead, activated sludge basins with a normal MLSS (e.g., 2,000 ¡V 4,000 mg L-1) in the mixed liquor and an efficient gas diffusion system with volumetric VOC transfer coefficient of around 10 ¡V 15 h-1 can be used for the removal of hydrophobic VOCs from the introduced gas. For achieving a removal of over 95% of the introduced toluene or similar hydrophobic VOCs, commercial air diffusers for aerobic biological wastewater treatment basins can be used with a submerged liquid depth of over 0.40 m over the diffusers and an aeration intensity (air flow rate/basin cross-sectional area) of lower than 5.0 m3 m-2 h-1.

Made available in DSpace on 2014-06-11T19:23:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-30Bitstream added on 2014-06-13T20:30:31Z : No. of bitstreams: 1 rodrigues_tt_me_ilha.pdf: 2332044 bytes, checksum: 6e277868f01ea21a46dfbf5c827109a7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Ensino Pesquisa e Extensão de Ilha Solteira (FEPISA) / A compreensão do escoamento em válvulas de compressores herméticos alternativos é de fundamental importância para introduzir modificações no projeto delas de maneira a aumentar a performance dos compressores, e por fim, dos ciclos de refrigeração. A válvula do compressor é um dispositivo ímpar, umas vez que seu funcionamento se dá pela ação da pressão exercida pelo escoamento, caracterizando um problema de forte interação fluido- estrutura. O uso da modelagem numérica através das ferramentas da mecânica dos fluidos computacional (CFD) tem se destacado como a alternativa mais dinâmica para o estudo do fenômeno. O trabalho desenvolvido foi voltado para o estudo numérico do escoamento através do difusor radial, o qual é um modelo simplificado da válvula, com o emprego do Método da Fronteira Imersa com Modelo Físico Virtual para a modelagem do disco superior do difusor (palheta). O ponto forte desta metodologia é que a representação de regiões sólidas é feita pelo cálculo de um campo de força, o qual é introduzido nas equações das células na vizinhança do sólido. Este procedimento dispensa o uso de malhas que se adaptam ao corpo, possibilitando o uso de malhas cartesianas convencionas para modelar geometrias complexas e móveis. A metodologia foi acoplada com a solução das equações governantes do escoamento em coordenadas cilíndricas através do Método dos Volumes Finitos. Inicialmente, a metodologia foi validada, utilizando como dados de referência resultados provenientes de estudos numéricos e experimentais, e foi avaliada a influência dos parâmetros do procedimento na qualidade final dos resultados. Na segunda etapa foram desenvolvidos estudos preliminares referentes ao movimento do disco superior, com a imposição artificial dos processos de abertura e fechamento da válvula. Os resultados obtidos mostraram que a metodologia adotada... / The fully understanding of the flow through automatic valves of alternative hermetic compressors is essentiall to introduce modifications in its project aiming the improvement of the compressor performance and, also, the refrigeration cycle. The compressor valve is a singular device, once its operation is ruled by the flow pressure, characterizing a case with a strong fluid-structure interaction. The using of numerical tools trough the methods of computational fluid dynamics (CFD) has gained especial attention due to its flexibility to study the phenomenon. The present work was developed to study numerically the flow through the radial diffuser, which is a simplified model of the valve, with the employment of the Immersed Boundary Method with Virtual Physical Model to modeling the superior disk (valve reed). The main advantage of this methodology is that the modeling of solid boundaries is performed with the calculus of a force field, which is introduced in the cells equations nearby the solid. This procedure dispenses the using of body-fitted meshes, enabling the adoption of conventional Cartesian meshes to model complex and moving geometries. The methodology was coupled with the solution of the governing equations in cylindrical coordinates though the Finite Volume Method. Firstly, the methodology was validated, confronting the results obtained with data from numerical and experimental studies, where the influence of the main parameters in the quality of the final results was evaluated. In the second step were developed preliminary studies concerning the movement of the superior disk, whose opening and closing movements were artificially imposed. The results obtained showed that the adopted methodology is quit promising and flexible, and can be employed in more refined studies to the comprehension of the flow through the valve regarding the fluid-structure interaction that rules the problem

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-06-28Bitstream added on 2014-06-13T20:30:31Z : No. of bitstreams: 1 anhejunior_sa_me_ilha.pdf: 2550289 bytes, checksum: 4299d702522bdb3a4b51de625099c77e (MD5) / Fundação de Ensino Pesquisa e Extensão de Ilha Solteira (FEPISA) / O presente trabalho refere-se à investigação experimental e numérica do escoamento em difusores radiais, que são usados como modelos de representação de sistemas de válvulas de compressores de refrigeração. Uma bancada experimental é projetada, construída e validada para medir a distribuição de pressão, sobre o disco frontal de um difusor radial de razão de diâmetro 3, para números de Reynolds de 1500 a 9000 e afastamento entre os discos frontal e anterior variando de 0,415mm a 0,705mm aproximadamente. Paralelamente, desenvolve-se um código computacional, baseado na metodologia de Volumes Finitos para malhas desencontradas, para simular o escoamento na geometria do difusor radial. O código computacional é primeiramente validado por meio dos resultados experimentais obtidos da bancada construída. Após sua validação, o código é usado para analisar o escoamento em um difusor de razão de diâmetro igual a 1,4, para números de Reynolds variando de 500 a 2500 e afastamento entre discos na fixa de 0,125 a 1,0mm. Os resultados numéricos mostram o surgimento de recirculação extendendo-se em toda região do difusor. Além disso, os resultados de perfil de pressão sobre o disco frontal fornecem forças e quedas totais de pressão no difusor que aumentam com o número de Reynolds e afastamento entre disco. Esse comportamento produz um ponto de mínima área efetiva de força localizado na faixa de , para números de Reynolds variando de 500 a 1500. Para número de Reynolds mais elevados, , a área efetiva de força sempre aumenta com o aumento do afastamento entre discos. A área efetiva de escoamento, outro parâmetro de interesse para a simulação do compressor, apresenta um crescimento linear com o afastamento entre discos, independentemente do número de Reynolds avaliado. / In this work, an experimental and numerical investigation of the flow in radial diffusers representing the valve system of refrigeration compressor is accomplished. An experimental bench is designed, build, and validated allowing the measurement of the pressure distribution on the frontal disk surface of a radial diffuser with diameter ratio equal to 3, for Reynolds number varying from 1500 to 9000 and distances between disks in the ranges of 0.415 to 0.705mm. In addition, a computational code based on the Finite Volume Methodology for staggered mesh is developed in order to simulate the flow though the radial diffuser. The computational code is firstly validated by using the experimental data obtained from the experimental bench. After its validation, the code is used for analyzing the flow through a radial diffuser with diameter ratio equal to 1.4, for Reynolds numbers varying from 500 to 2500 and distance between disks in the range of 0.125 a 1.0 mm. The numerical results showed recirculation regions extending through the whole diffuser for the majority of the analyzed cases. The pressure profiles on the frontal disk surface produce forces and total pressure drops through the diffuser that increase with both Reynolds number and distance between disks. There is a minimum effective force area in the range of , for Reynolds numbers varying from 500 a 1500. For higher Reynolds numbers, , the effective force area always increases for increasing distance between disks. The effective flow area, another parameter used for simulating the compressor, increases linearly with the distance between disks, independently of the Reynolds number.

Orientador: Ricardo Alan Verdu Ramos / Banca: Emanuel Rocha Woiski / Banca: Eduardo Mirko Valenzuela Turdera / Resumo: Neste trabalho são realizadas análises termodinâmicas, termoeconômicas e econômicas aplicadas a uma usina de açúcar e álcool com processo de extração por difusão, envolvendo desde a configuração inicial de implantação da usina até a expansão para uma planta moderna de potência cujo principal objetivo é a produção de excedente de energia elétrica. São consideradas quatro situações: a configuração inicial da planta, definida como Caso 1, que opera visando gerar energia elétrica apenas para o próprio consumo e, também, vapor para o processo de produção de álcool; na seqüência tem-se a configuração, definida como Caso 2, onde o intuito é produzir o máximo de energia elétrica que o turbogerador pode fornecer e vapor para a produção de álcool e, também açúcar; na configuração seguinte, definida como Caso 3, é adicionada na planta uma turbina de condensação visando um melhor aproveitamento para a geração de energia elétrica; e, por fim, na última configuração, definida como Caso 4, é adicionada uma nova turbina de extração condensação e uma caldeira de alta pressão, priorizando a geração de energia elétrica / Abstract: In this work thermodynamic, thermoeconomic and economical analyses were accomplished in a sugar-alcohol factory with extraction process for diffusion, considering the initial configuration implanted until the expansion for a modern power plant whose main objective is the production of electric power surplus. Four situations were considered: the initial configuration of the plant, defined as Case 1, that operates generating electric power just for the own consumption and, also, steam for the alcohol production process; in sequence it was studied the configuration defined as Case 2, where the intention is to produce the maximum of electric power that the turbogenerator can supply and steam for the production of alcohol and, also, sugar; in the following configuration, defined as Case 3, it is added in the plant a condensation turbine for a better use in the electric power generation; and, finally, in the last configuration, defined as Case 4, it is added a new extractioncondensation turbine and a high pressure boiler, prioritizing the electric power generation / Mestre