In this paper is carried out basic design and calculation of tube heat exchanger with a straight tube bundle with installed systém of disk and doughnut baffles. The calculation included pressure losses and heat transfer coefficient of tubular space and shell side. Then CFD model was made for parametric study, which was focused on influence of change of the baffles geometry on the heat output of the exchanger and the pressure loses on the shell side.

Sloshing phenomena could seriously damage tank structures and reduce its lifetime. On the one hand, studies directly recommend the use of baffles to solve these problems, nevertheless on the other hand the existence of small tanks or plastic tanks without baffles confuse and complicate the case. The first aim in this thesis is to clarify the necessity of baffles for a particular diesel tank L120 H-Generation in Volvo front loaders. Then, the second aim is to improve the existing design. Four configurations are proposed and checked independently. Experiments in the lab, FEM static stresses analyses and vibrational simulations are done in order to fulfill the requirements. The conclusion of this thesis is that the dissipation of energy is highly recommended, so having an oblique baffle with holes could be a good way to reduce the sloshing and extend the lifetime of the tank.

In many hydroelectric projects there is a need to safely dissipate the energy associated with the elevation of the water surface. When the flow is not passing through the turbines, bypass valves are often used. A valve that is commonly used is the fixed-cone valve. Fixed-cone valves, also known as Howell-Bunger valves, are devices often used to safely reduce flow energy at dams with medium to high heads. The valve directs the outflow into a conical hollow jet, which requires a large area for energy dissipation. The flow is controlled by an adjustable sleeve, also known as the gate which surrounds the valve and requires minimal power for operation even for large valves. Depending on the installation, the conical jet may need to be controlled by installing a fixed stationary hood or other structure to contain and direct the conical jet. While the hood reduces the spray, the use of the hood causes the formation of a concentrated hollow jet having a high velocity. To eliminate the hollow jet and dissipate much of the associated energy, the hood can have interior baffles. If the hood is not precisely placed relative to the valve, a phenomenon, known as backsplash, will occur. Backsplash is when a significant amount of water exits the upstream end of the hood. Backsplash is a concern for operators because it can prevent access to the valve during operation and can flood valve vaults. Because the use of fixed-cone valves and baffled-hoods are becoming more popular, the need for guidelines to correctly position the hood relative to the valve will benefit both engineers and contractors. In some hydroelectric sites, submerging the fixed-cone valve is used to control the spray and dissipate energy. Submerging the valve can have can produce violent flow conditions which can cause damage to a structure or heavy erosion. The use of a submerged fixed-cone valve is rarely used, and a submerged valve used with a baffled-hood has never been constructed. The study performed shows that the use of a baffled hood with a fixed-cone valve in submerged conditions performs well. The results may lead the way for more submerged fixed-cone valves in the future.

No description available.

As lagoas de estabilização têm sido, por suas características operacionais e baixos custos de implantação, consideradas como a opção mais viável para tratamento de águas residuárias em pequenas e médias comunidades. O sistema composto por lagoa anaeróbia e facultativa em série é o mais empregado no Brasil. Com o avanço no monitoramento das lagoas de estabilização que se iniciou na década de 90, no caso do Estado de São Paulo pela SABESP, e que hoje se encontra bastante estruturado, periódico e confiável, nota-se que esses sistemas apesar de projetados seguindo as técnicas mais recentes, não possuem a eficiência esperada quando em operação. Tornam-se então prementes os estudos no sentido de melhorar o desempenho dos sistemas existentes e fornecer subsídios para novos projetos de lagoas de estabilização. Este trabalho estudou a utilização de chicaneamento nas lagoas de estabilização verificando a influência das chicanas no comportamento hidrodinâmico e desempenho desses sistemas além da utilização de macrófitas aquáticas no processo de tratamento de águas residuárias. Concluiu-se que mesmo com aumento de eficiência de remoção de DQO, 'DBO IND.5', nitrogênio Kjedahl e amoniacal, para ambos os casos: lagoa com aguapé e lagoa com lentilha d’água, os inúmeros problemas operacionais e aumento de custos que surgiram da aplicação das macrófitas aquáticas tornam desaconselhável o uso de aguapé e lentilha d’água em lagoas de tratamento de esgoto. Com relação ao chicaneamento o sistema que mais se aproximou dos valores teóricos, com relação ao tempo de detenção hidráulico e número de dispersão (d), foi a lagoa com chicaneamento longitudinal, melhorando o comportamento hidráulico do sistema, podendo ser considerado uma medida simples e de baixo custo para incrementar a eficiência de lagoas de estabilização / Due to the operational characteristics and low investment costs stabilization ponds have been considered as the most viable option for wastewater treatment in small and medium size communities. Anaerobic and facultative ponds in series are the most used in Brazil. With the progress of monitoring of the stabilization ponds, that was initiated in the decade of 1990 in the State of São Paulo by SABESP, it was observed that these systems do not possess the expected efficiency when in operation, although they were designed following the best available knowledge at that time. Thus, new studies were direct to improve the performance of the existing systems and to supply subsidies for new projects of stabilization ponds. This research examines, separately, the use of baffles and macrophytes in a pilot scale stabilization pond verifying the influence of these elements on the hydrodynamic behavior and performance of the wastewater treatment. It was concluded that although there is an increase in removal efficiency of DQO, 'DBO IND.5', nitrogen Kjedahl and ammoniacal, the several operational problems and increase of costs that had appeared with the application of water hyacinths and duckweed in the pond, it is not recommended to use these aquatic plants in sewer treatment. Concerning the use of baffles the system that came closer to the theoretical values, in relation to the hydraulic time of detention and number of dispersion (d), was the pond with longitudinal baffles. These baffles improved the hydraulic behavior of the system and are a simple measure and of low cost to develop the efficiency of stabilization ponds

As lagoas de estabilização têm sido, por suas características operacionais e baixos custos de implantação, consideradas como a opção mais viável para tratamento de águas residuárias em pequenas e médias comunidades. O sistema composto por lagoa anaeróbia e facultativa em série é o mais empregado no Brasil. Com o avanço no monitoramento das lagoas de estabilização que se iniciou na década de 90, no caso do Estado de São Paulo pela SABESP, e que hoje se encontra bastante estruturado, periódico e confiável, nota-se que esses sistemas apesar de projetados seguindo as técnicas mais recentes, não possuem a eficiência esperada quando em operação. Tornam-se então prementes os estudos no sentido de melhorar o desempenho dos sistemas existentes e fornecer subsídios para novos projetos de lagoas de estabilização. Este trabalho estudou a utilização de chicaneamento nas lagoas de estabilização verificando a influência das chicanas no comportamento hidrodinâmico e desempenho desses sistemas além da utilização de macrófitas aquáticas no processo de tratamento de águas residuárias. Concluiu-se que mesmo com aumento de eficiência de remoção de DQO, 'DBO IND.5', nitrogênio Kjedahl e amoniacal, para ambos os casos: lagoa com aguapé e lagoa com lentilha d’água, os inúmeros problemas operacionais e aumento de custos que surgiram da aplicação das macrófitas aquáticas tornam desaconselhável o uso de aguapé e lentilha d’água em lagoas de tratamento de esgoto. Com relação ao chicaneamento o sistema que mais se aproximou dos valores teóricos, com relação ao tempo de detenção hidráulico e número de dispersão (d), foi a lagoa com chicaneamento longitudinal, melhorando o comportamento hidráulico do sistema, podendo ser considerado uma medida simples e de baixo custo para incrementar a eficiência de lagoas de estabilização / Due to the operational characteristics and low investment costs stabilization ponds have been considered as the most viable option for wastewater treatment in small and medium size communities. Anaerobic and facultative ponds in series are the most used in Brazil. With the progress of monitoring of the stabilization ponds, that was initiated in the decade of 1990 in the State of São Paulo by SABESP, it was observed that these systems do not possess the expected efficiency when in operation, although they were designed following the best available knowledge at that time. Thus, new studies were direct to improve the performance of the existing systems and to supply subsidies for new projects of stabilization ponds. This research examines, separately, the use of baffles and macrophytes in a pilot scale stabilization pond verifying the influence of these elements on the hydrodynamic behavior and performance of the wastewater treatment. It was concluded that although there is an increase in removal efficiency of DQO, 'DBO IND.5', nitrogen Kjedahl and ammoniacal, the several operational problems and increase of costs that had appeared with the application of water hyacinths and duckweed in the pond, it is not recommended to use these aquatic plants in sewer treatment. Concerning the use of baffles the system that came closer to the theoretical values, in relation to the hydraulic time of detention and number of dispersion (d), was the pond with longitudinal baffles. These baffles improved the hydraulic behavior of the system and are a simple measure and of low cost to develop the efficiency of stabilization ponds

There is a good deal of uncertainty and sensitivity in the results for wave impact. In a practical situation, many parameters such as the wave climate will not be known with any accuracy especially the frequency and severity of wave breaking. Even if the wave spectrum is known, this is usually recorded offshore, requiring same sort of (linear) transfer function to estimate the wave climate at the seawall. What is more, the higher spectral moments will generally be unknown. Wave breaking, according to linear wave theory, is known to depend on the wave spectrum, see Srokosz (1986) and Greenhow (1989). Not only is the wave climate unknown, but the aeration of the water will also be subject to uncertainty. This affects rather dramatically the speed of sound in the water/bubble mixture and hence the value of the acoustic pressure that acts as a maximum cutoff for pressure calculated by any incompressible model. The results are also highly sensitive to the angle of alignment of the wave front and seawall. Here we consider the worst case scenario of perfect alignment. Given the above, it seems sensible to exploit the simple pressure impulse model used in this thesis. Thus Cooker (1990) proposed using the pressure impulse P(x, y) that is the time integral of the pressure over the duration of the impact. This results in a simplified, but much more stable, model of wave impact on the coastal structures, and forms the basis of this thesis, as follows: Chapter 1 is an overview about this topic, a brief summary of the work which will follow and a summary of the contribution of this thesis. Chapter 2 gives a literature review of wave impact, theoretically and experimentally. The topics covered include total impulse, moment impulse and overtopping. A summary of the present state of the theory and Cooker’s model is also presented in Chapter 2. In Chapter 3 and Chapter 4, we extend the work of Greenhow (2006). He studied the berm and ditch problems, see Chapter 3, and the missing block problem in Chapter 4, and solved the problems by using a basis function method. I solve these problems in nondimensionlised variables by using a hybrid collocation method in Chapter 3 and by using the same method as Greenhow (2006) in Chapter 4. The works are extended by calculating the total impulse and moment impulse, and the maximum pressure arising from the wave impact for each problem. These quantities will be very helpful from a practical point of view for engineers and designers of seawalls. The mathematical equations governing the fluid motion and its boundary conditions are presented. The deck problem together with the mathematical formulation and boundary conditions for the problem is presented in Chapters 5 and 6 by using a hybrid collocation method. For this case, the basis function method fails due to hyperbolic terms in these formulations growing exponentially. The formulations also include a secular term, not present in Cooker’s formulation. For Chapter 5, the wave hits the wall in a horizontal direction and for Chapter 6, the wave hits beneath the deck in a vertical direction. These problems are important for offshore structures where providing adequate freeboard for decks contributes very significantly to the cost of the structure. Chapter 7 looks at what happens when we have a vertical baffle. The mathematical formulation and the boundary conditions for four cases of baffles which have different positions are presented in this chapter. We use a basis function method to solve the mathematical formulation, and total impulse and moment impulse are investigated for each problem. These problems are not, perhaps, very relevant to coastal structures. However, they are pertinent to wave impacts in sloshing tanks where baffles are used to detune the natural tank frequencies away from environmental driving frequencies (e.g ship roll due to wave action) and to damp the oscillations by shedding vortices. They also provide useful information for the design of oscillating water column wave energy devices. Finally, conclusions from the research and recommendations for future work are presented in Chapter 8.

The aim of diploma thesis is creating calculation algorithms off single types unconventional heat transfer equipment and their aplication in thermal - hydraulic calculations in the industrial aplication . The main attention is paid to shell and tube heat exchangers with ROD and disc baffle system and radiation heat exchanger. All of these exchangers are used mainly in process of waste thermic destruction. The theoretical part of the work describes construction details of each heat exchanger and calculation algorithms of these equipments. The practical part of the work applies theoretic calculation alghortims in the industrial aplication which is design and rating. In the final part advantages and disadvantages of results have been assessed for construction and process aspects.

Orientadora: Profa. Dra. Juliana Tófano de Campos Leite Toneli / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2014. / Os tanques com impulsores mecânicos são empregados nas indústrias químicas, petroquímicas, alimentícia, farmacêutica e mineral, como reatores químicos, diluidores, decantadores, misturadores e trocadores de calor. A transmissão de calor em tanques com agitação é realizada através das jaquetas, serpentinas helicoidais, serpentinas em espiral e chicanas tubulares verticais, sendo que existe uma carência de dados na literatura sobre a utilização das chicanas tubulares, em projetos em escala industrial. O presente estudo teve por objetivo principal comparar a transferência de calor e o consumo energético em tanques com impulsores mecânicos, axial e radial, equipados com chicanas tubulares verticais. Como objetivos específicos, o presente estudo visou determinar correlações semi-empíricas para o coeficiente convectivo no escoamento externo, em relação aos impulsores mecânicos utilizados em função dos parâmetros de similaridade Reynolds e Prandtl, e avaliar o efeito do impulsor mecânico sobre a potência consumida e a transmissão de calor. A unidade experimental consistiu, basicamente, de um tanque de acrílico com um volume útil de 50 litros, um impulsor mecânico axial, um impulsor radial tipo turbina, um motor elétrico de 2,5 hp e uma chicana tubular com 4 bancos de tubos de cobre. Os fluidos frios utilizados foram água e solução de sacarose com concentrações de 20% e 50% em massa. O fluido quente utilizado foi água à temperatura constante de 60°C e vazão de 1,2 LPM. Os ensaios foram realizados alternando as rotações na faixa de 90 a 330 RPM e a temperatura de entrada do fluido frio no intervalo de 28°C a 45°C. A potência consumida por ambos os impulsores mecânicos foi determinada a partir da técnica da medição do torque gerado no motor elétrico. O modelo obtido para a previsão do coeficiente externo de convecção, com o impulsor axial apresentou, um desvio médio de 21% e o modelo para o impulsor radial, um desvio médio de 25%. A partir dos modelos obtidos, verificou-se que o impulsor radial incrementa a transmissão de calor em 43% quando comparado com o impulsor axial. A rotação ideal para a maior transmissão de calor, durante o aquecimento das soluções, com o menor consumo de energia foi de 300 rpm. A partir das curvas simultâneas do número de potência e do número de Nusselt, conclui-se que o impulsor axial é o mais indicado para o aquecimento tendo em vista o seu baixo consumo de potência em relação ao impulsor radial. / EThe tanks with mechanical impellers are employed in chemical, petrochemical, food, pharmaceutical and mineral industries, as chemical reactors, thinners, decanters, mixers and heat exchangers. The heat transmission in tanks with agitation is performed through the jackets, helical coils, coils in spiral and vertical tubular baffles, considering that there is a lack of data in the literature on the use of tubular baffles, in industrial scale projects. The present study aimed to compare the main heat transfer and energy consumption in tanks with mechanical axial and radial impellers equipped with tubular vertical baffles. As specific objectives, this study aimed to determine correlations for convective coefficient in the external flow in relation to mechanical impellers used in function of Reynolds and Prandtl similarity parameters, and evaluate the mechanical effect on power consumption and heat transmission. The experimental unit consisted primarily of an acrylic tank with a useful volume of 50 liters, an axial mechanical and turbine type radial impeller, a 2.5 hp electric motor and a tubular chicanery with 4 banks of copper tubes. The cold fluids applied were water, and sucrose solution with concentrations of 20% and 50% by mass. The hot fluid applied was water at constant temperature of 60° C and a 1.2 LPM flow. The tests were carried out in the range of rotations by 90 to 330 RPM and the cold fluid inlet temperature in the range from 28° C to 45° C. The power consumed by both mechanical impellers was determined through the thechnique of measurement of the torque generated at electric motor. The model obtained for external coefficient prediction of convection with the axial impeller presented an average deviation of 21% and the template for the radial impeller, a standard deviation of 25%. From the models obtained, it was found that the radial impeller increases the transmission of heat in 43% when compared with the axial impeller. The ideal rotation for greater heat transfer during heating of the solutions with the lowest energy consumption amounted to 300 rpm. From the number of concurrent power curves and Nusselt number, it is concluded that the axial impeller is the most indicated for heating in view of its low power consumption compared to radial impeller.

Made available in DSpace on 2015-05-07T14:49:38Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1400231 bytes, checksum: fb9f24d41beb924c130d174f918f19f8 (MD5) Previous issue date: 2005-12-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this thesis is to evaluate the performance of anaerobic filter with baffles (FAC) for the post treatment of anaerobic effluent and using rings cut from PET bottles as filling medium. The experiment was carried out in three phases characterized by the hydraulic retention times of 7, 9 and 10 days, respectively. The analysis of the UASB and FAC effluents was carried out weekly to evaluate the removal efficiency of organic material expressed as BOD5 e COD, solids and its different fractions, nutrients (nitrogen and phosphorus) and indicators of faecal contamination (thermotolerant Coliforms). The results showed that there were no significant differences between the FAC effluent during the three phases with respect to organic material and suspended solids (at 5% significance level), but there were differences in the electric conductivity, nitrogen and thermotolerant Coliforms. The FAC presented good performance of organic material removal (65% for COD and 64% for BOD5 during the first phase) and suspended solids (81% for TSS and 83% for VSS during the first phase). Thus it can be noted that the FAC presented good post treatment efficiency of anaerobic effluents, resulting in clarified effluent with low concentrations of organic material (12mg BOD5.L-1), suspended solids (<10 mg TSS. L-1) and turbidity (<10 UNT). With respect to sanitary quality the produced effluent had concentrations of thermotolerant in the range of 103 to 104 UFC.100 mL-1, hence above the standards established by the WHO (1989) for utilization in irrigation without restrictions. / O presente trabalho teve como objetivo avaliar o desempenho de filtro anaeróbio de chicanas (FAC) no pós-tratamento de efluente anaeróbio, usando garrafas PET como material de enchimento. O experimento foi realizado em três fases, delimitado pelos três tempos de detenção hidráulicas, 7, 9 e 10 dias, respectivamente. As análises dos efluentes do reator UASB e do FAC foram realizadas semanalmente, averiguando a remoção de matéria orgânica na forma de DBO5 e DQO, sólidos e suas frações, nutrientes (nitrogênio e fósforo) e indicadores de contaminação fecal (coliformes termotolerantes). Os resultados mostraram que não ocorreram diferenças significativas no efluente do FAC entre as três fases, em relação a matéria orgânica e sólidos (ao nível de 5%), mas houve diferença quanto a condutividade elétrica, nitrogênio e coliformes termotolerantes. O FAC apresentou bom desempenho quanto à remoção de matéria orgânica (65% para DQO e 64% para DBO5 durante a 1ª fase) e sólidos suspensos (81% para SST e 83% para SSV durante a 1ª fase). Diante desses resultados, observa-se que o FAC apresentou boa eficiência no pós-tratamento de efluente anaeróbio resultando em um efluente clarificado com baixas concentrações de matéria orgânica (12mg DBO5.L-1), sólidos suspensos (<10 mg SST. L-1) e turbidez (<10 UNT). Com relação à qualidade sanitária, o efluente produzido apresentava concentrações de coliformes termotolerantes variando de 103 a 104 UFC.100 mL-1, portanto valores acima dos padrões estabelecidos pelo OMS (1989) para ser utilizado em irrigação irrestrita.