Shell and tube heat exchangers and their use in cooling processes are the major topic of this thesis. The theoretical part of the thesis starts with the mechanisms of heat transfer and then deals with shell and tube heat exchangers. Their position, design specifications and equations for calculations are given. In the experimental part, the heat transfer on semi-operating shell and tube heat exchangers with baffles and glass or silicon carbide heat exchange surface is examined by cooling the humid air by 50% propylene glycol in tubes. For four or five coolant flows and three airflows, input and output flow temperatures including relative air humidity were measured. Differences in exchanged heat between the exchangers were negligible due to the low local air heat transfer coefficient, although silicon carbide has two orders of magnitude better thermal conductivity than glass. Much higher efficiency was performed by the carbide heat exchanger because the difference between air outlet temperature and liquid inlet temperature was one and half times higher for the glass heat exchanger. That was reflected in a decrease in mean temperature difference, which resulted in a 16 % higher experimental heat transfer coefficient compared with the glass surface. The theoretical model using the j factor, the correction factors for the baffles, and the correction for air humidity condensation have proven to be appropriate. For the glass surface, for the highest air flow rates the model gives an appropriate heat-transfer coefficient; at lower flow rates it gives slightly higher values. For the silicon carbide surface, it gives a lower heat-transfer coefficient because the model failed to consider a lower mean temperature difference. The results also evaluate the heat loss through the shell and the heat exchanged in addition by air humidity condensation.

The different technologies of passive cooling concepts have to rely on a good thermal coupling between a building's thermal mass and indoor air. In many cases, the ceiling is the only surface remaining for a good coupling. Further research is necessary to investigate discrepancies between existing correlations. Therefore, the overall aim of the work described in this thesis is the investigation of heat transfer at a heated ceiling in an experimental chamber. Acoustic baffles obstruct the surface of the ceiling and impede heat transfer. However, there is nearly no published data about the effect of such baffles on heat transfer. Available results from simulations should be verified with an experimental investigation. Consequently, one of the primary aims of this work was to experimentally determine the influence of such acoustic baffles. A suitable experimental chamber has been built at Biberach University of Applied Sciences. The thesis describes the experimental chamber, the experimental programme as well as results from five different test series. With a value of ±0.1Wm⁻²K⁻¹ for larger temperature differences, uncertainty in resulting convective heat transfer coefficients for natural convection is comparable to that of results from an existing recent experimental work often recommended for use. Additionally, total heat transfer (by convection and radiation) results are presented. Results are given for natural, forced and mixed convection conditions at an unobstructed heated ceiling. Furthermore, results for acoustic baffles in both an unventilated and a ventilated chamber are shown. Natural convection results show a very good agreement with existing correlations. Under mixed convection conditions, convective heat transfer at an unobstructed ceiling decreases to the limiting case described by natural convection. Installation of acoustic baffles leads to a reduction in total heat transfer (convection and radiation) between 20% and 30% when compared to the case of an unobstructed ceiling.

Este trabalho tem como objetivo analisar estratégias de iluminação natural utilizadas nos estágios iniciais do projeto de arquitetura capazes de aumentar a qualidade da iluminação e a conservação de energia nos edifícios escolares. Essas estratégias têm sido aplicadas com sucesso em edifícios escolares em vários países, melhorando o desempenho e o bem-estar dos estudantes e conservando energia. Entre essas estratégias, o autor selecionou um dispositivo zenital para iluminação natural com seleção angular e difusores opacos, realizou um ensaio experimental em um modelo físico reduzido de uma sala de aula padrão, sob condições de céu real e analisou comparativamente os resultados. O estudo mostrou que a adoção de uma metodologia para utilizar estratégias como a analisada neste trabalho pode conseguir um adequado controle da radiação solar para evitar a incidência direta da luz do Sol, evitar o ofuscamento e o aquecimento excessivo de ambientes de salas de aula em climas quentes e, ao mesmo tempo, aproveitar a iluminação natural, tanto difusa quanto direta refletida, para obter maior conforto visual e economizar energia. / This work aims to analyse daylighting strategies applied in early stages of architectural design as to improve lighting quality and energy savings in school buildings. Similar strategies have already been successfully applied in many countries around the world, enhancing student?s performance and well being while helping to save energy. Among the strategies studied, the author describes an experiment under real sky conditions using a physical scale model of a standard classroom equipped with a roof monitor combined with an overhang and interior vertical diffusing baffles as a way to check its influence in interior lighting conditions. The experiment has shown that the use of daylighting strategies can promote an adequate control of solar radiation, avoiding direct sunlight penetration inside the classrooms, limiting glare problems and excessive heat of hot climates. At the same time, such strategies optimise both direct and defuse use of daylight to improve visual comfort and energy savings.

Made available in DSpace on 2015-09-25T12:23:30Z (GMT). No. of bitstreams: 1 VANESSA F SILVA.pdf: 1400231 bytes, checksum: fb9f24d41beb924c130d174f918f19f8 (MD5) Previous issue date: 2005-12-22 / 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.

Este trabalho tem como objetivo analisar estratégias de iluminação natural utilizadas nos estágios iniciais do projeto de arquitetura capazes de aumentar a qualidade da iluminação e a conservação de energia nos edifícios escolares. Essas estratégias têm sido aplicadas com sucesso em edifícios escolares em vários países, melhorando o desempenho e o bem-estar dos estudantes e conservando energia. Entre essas estratégias, o autor selecionou um dispositivo zenital para iluminação natural com seleção angular e difusores opacos, realizou um ensaio experimental em um modelo físico reduzido de uma sala de aula padrão, sob condições de céu real e analisou comparativamente os resultados. O estudo mostrou que a adoção de uma metodologia para utilizar estratégias como a analisada neste trabalho pode conseguir um adequado controle da radiação solar para evitar a incidência direta da luz do Sol, evitar o ofuscamento e o aquecimento excessivo de ambientes de salas de aula em climas quentes e, ao mesmo tempo, aproveitar a iluminação natural, tanto difusa quanto direta refletida, para obter maior conforto visual e economizar energia. / This work aims to analyse daylighting strategies applied in early stages of architectural design as to improve lighting quality and energy savings in school buildings. Similar strategies have already been successfully applied in many countries around the world, enhancing student?s performance and well being while helping to save energy. Among the strategies studied, the author describes an experiment under real sky conditions using a physical scale model of a standard classroom equipped with a roof monitor combined with an overhang and interior vertical diffusing baffles as a way to check its influence in interior lighting conditions. The experiment has shown that the use of daylighting strategies can promote an adequate control of solar radiation, avoiding direct sunlight penetration inside the classrooms, limiting glare problems and excessive heat of hot climates. At the same time, such strategies optimise both direct and defuse use of daylight to improve visual comfort and energy savings.

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