An emerging trend in the building services industry is the installation of passive deaerators on the flow line of domestic wet central heating systems. To date, no data and theoretical models predicting the two-phase flow characteristics in domestic wet central heating systems are available in the open literature. This gap in literature has prevented essential design improvements to passive deaerators thus impeding the efficiency enhancement of such devices. Hence, the current study is aimed at assisting designers of deaeration devices by providing fundamental data and model correlations with respect to the two-phase flow characteristics typical in a wet domestic central heating system. For this purpose an experimental research project was adopted and several studies were carried out, including; (1) a comprehensive review to understand the background of the phenomena, (2) the design and construction of an experimental test rig to conduct the necessary investigations into the phenomenon of two-phase flow in domestic wet central heating systems, (3) the development of a reliable image capture and analysis technique, (4) the completion of a number of experiments to investigate typical bubble sizes, volumetric void fractions, bubble distributions and nucleation and dissolution rates and (5) the correlation of the data gathered as part of the present study with existing bubble size, nucleation and dissolution prediction models. This research has, for the first time, provided an in depth analysis into two-phase flow characteristics in wet domestic central heating systems through the use of a high speed camera and image analysis techniques. The two-phase phenomenon finds its origins in high dissolved gas concentrations present in the water flowing through the closed loop system, thus resulting in super saturation conditions at the primary heat exchange wall conditions. Bubble sizes at the boiler flow line were found to be dependent on the bulk fluid velocity, heat flux and pressure, with a measured mean diameter in the range of 0.13 mm to 0.39 mm. The Winterton (1972a) force balance model for bubble size prediction was in reasonable agreement with the experimental results. This model was further improved through the correlation of our data with the inclusion of dimensionless groups. Bubble nucleation rates have been calculated in the range of 0.3 to 4 bubbles / cm2 s with total system bubble production rates measured in the range of 784 to 6920 bubbles per second. Bubble nucleation rates have been calculated through the consideration of the heat exchanger surface under super saturation conditions. A correlation for the model by Hepworth et al. (2003) for nonclassical heterogeneous nucleation is proposed based on the experimental data gathered during the present study. Experimental results have shown dissolution rates for the bubble size ratio in the range of 0.4 to 12 % per second with system conditions. A modification of the model developed by Epstein and Plesset (1950) for stationary bubble dissolution is proposed with the inclusion of the Sherwood number to capture the effects of turbulent diffusion. The volumetric void fraction distribution in vertical pipes was found to be quasi-homogenous across the pipe section while being strongly dependent on gravitational and turbulence effects in horizontal pipe bubbly flow. A CFD simulation predicted the volumetric void fraction distribution with reasonable accuracy.

Background: Electricity tariffs charged by Eskom have sharply increased over the past three years, with a 25% annual increase approved by Nersa until April 2012. There is no indication on what to expect in the future with regard to electricity tariffs. Many South Africans are searching for ways to save on their monthly electricity bills by seeking out alternative water heating systems. Solar geysers became a popular investment option, but this might not be the best options available on the market. Purpose: The purpose of this study is to determine the most financially viable investment option in order to reduce electricity cost when it comes to water heating systems for use in households. This is done by comparing the capital expenditure and operational cost needed with the financial benefits generated by the investment, taking into consideration the size of the household. Design and method: A literature study was done on the different alternative water heating systems in order to obtain a better understanding of how these systems operate and what savings they can generate. Different investment appraisals were identified and a literature review was performed in order to identify the most appropriate investment appraisals for the purpose of this study. It was found that the net present value, equivalent annual annuity, internal rate of return, modified internal rate of return, accounting rate of return, discounted payback period and the economic value added were the best investment appraisal methods to use for the purpose of this study. Findings and conclusion: It was found that the five investment options identified in the literature review would all, to some extent, be financially viable to implement within households with high as well as low volume hot water consumption. All the investment appraisals gave positive outcomes. The conclusion was made that a saving will be generated on the monthly electricity bill no matter what alternative water heating system were to be installed in the place of a conventional geyser. Recommendations: It is recommended that a household with low volume hot water consumption should install a time switch as this investment option renders the highest IRR, MIRR, ARR and discounted payback period. The second best investment option for a household with low volume hot water consumption is a heat pump and the third best option is a gas geyser. For a household with high volume hot water consumption, the best investment options is again a time switch, as this renders the best IRR, MIRR, ARR and discounted payback period. The second best investment option is a heat pump, with a gas geyser as the third best investment option. Value of the research: This study focuses on five alternative water heating systems for a household within South Africa in times where electricity charges sharply increase. The financial viability of each of the alternatives is determined through various investment appraisals and the best option can be identified by comparing the outcomes of the alternatives. Furthermore, each individual is able to determine the viability of the alternatives by using the Excel model attached to this study and by inputting his/her own variables, where applicable. Research limitation: Limited literature was available on the different alternative water heating systems. No indication could be found of the maintenance cost of the different water heating systems. Assumptions had to be made with regard to households, although no two households are the same. Areas for further research: The same study could be performed, but with the focus on small businesses and large organisations. Furthermore, a study could be performed to determine the appropriate discount rate for individuals as well as the maintenance cost for water heating systems. / Thesis (MCom (Management Accountancy))--North-West University, Potchefstroom Campus, 2012

O objetivo deste trabalho é investigar o desempenho energético de dois diferentes tipos de sistemas de aquecimento de piscinas: á gás natural e por bomba de calor elétrica. Foi realizada instrumentação em duas piscinas localizadas em uma mesma academia, cada uma delas dotada de um dos tipos de sistema de aquecimento. Além destas duas piscinas, que são objeto de investigação desta pesquisa, outras quatro piscinas, localizadas cada uma em um local distinto na cidade de São Paulo, também receberam instrumentação e a coleta de dados está sendo executada através de sistemas de aquisição de dados, para posterior análise e novos trabalhos de pesquisa. Como resultados da análise das duas piscinas, obteve-se um coeficiente de desempenho - COP, médio para o sistema de aquecimento por bomba de calor igual a 4. Para o sistema a gás natural, os resultados para a eficiência global do sistema indicaram 76%, ao passo que o rendimento apenas dos aquecedores foi de 82%. As análises dos dados permitiram comprovar a influência da temperatura ambiente sobre o COP da bomba de calor. Quanto menor a temperatura do ar, menor o COP. A Temperatura do ar também mostrou forte influência sobre o consumo de energia. / The aim of this research is to investigate the energetic performance of two distinct kinds of swimming pool heating systems: gas-fired and electric heat pump. A practical instrumentation research was prepared in these two indoor swimming pools, placed in the same location. Besides these, other four swimming pool, placed each in a different ambient in the city of São Paulo also received the instrumentation so that it will be possible to run future researches, once the data is already being collected by the data loggers installed. As a result of the data analysis, it was found that the average coefficient of performance of the heat pumps studied is 4. For the natural gas fired system, the global efficiency factor was found to be 76%. The efficiency of the heaters isolated was found to be 82%. This research showed that the COP of heat pump systems has strong correlation with the air temperature. The lower the air temperature, the lower the COP. Temperature also has strong influence on the consumption of energy.

Background: Electricity tariffs charged by Eskom have sharply increased over the past three years, with a 25% annual increase approved by Nersa until April 2012. There is no indication on what to expect in the future with regard to electricity tariffs. Many South Africans are searching for ways to save on their monthly electricity bills by seeking out alternative water heating systems. Solar geysers became a popular investment option, but this might not be the best options available on the market. Purpose: The purpose of this study is to determine the most financially viable investment option in order to reduce electricity cost when it comes to water heating systems for use in households. This is done by comparing the capital expenditure and operational cost needed with the financial benefits generated by the investment, taking into consideration the size of the household. Design and method: A literature study was done on the different alternative water heating systems in order to obtain a better understanding of how these systems operate and what savings they can generate. Different investment appraisals were identified and a literature review was performed in order to identify the most appropriate investment appraisals for the purpose of this study. It was found that the net present value, equivalent annual annuity, internal rate of return, modified internal rate of return, accounting rate of return, discounted payback period and the economic value added were the best investment appraisal methods to use for the purpose of this study. Findings and conclusion: It was found that the five investment options identified in the literature review would all, to some extent, be financially viable to implement within households with high as well as low volume hot water consumption. All the investment appraisals gave positive outcomes. The conclusion was made that a saving will be generated on the monthly electricity bill no matter what alternative water heating system were to be installed in the place of a conventional geyser. Recommendations: It is recommended that a household with low volume hot water consumption should install a time switch as this investment option renders the highest IRR, MIRR, ARR and discounted payback period. The second best investment option for a household with low volume hot water consumption is a heat pump and the third best option is a gas geyser. For a household with high volume hot water consumption, the best investment options is again a time switch, as this renders the best IRR, MIRR, ARR and discounted payback period. The second best investment option is a heat pump, with a gas geyser as the third best investment option. Value of the research: This study focuses on five alternative water heating systems for a household within South Africa in times where electricity charges sharply increase. The financial viability of each of the alternatives is determined through various investment appraisals and the best option can be identified by comparing the outcomes of the alternatives. Furthermore, each individual is able to determine the viability of the alternatives by using the Excel model attached to this study and by inputting his/her own variables, where applicable. Research limitation: Limited literature was available on the different alternative water heating systems. No indication could be found of the maintenance cost of the different water heating systems. Assumptions had to be made with regard to households, although no two households are the same. Areas for further research: The same study could be performed, but with the focus on small businesses and large organisations. Furthermore, a study could be performed to determine the appropriate discount rate for individuals as well as the maintenance cost for water heating systems. / Thesis (MCom (Management Accountancy))--North-West University, Potchefstroom Campus, 2012

O objetivo deste trabalho é investigar o desempenho energético de dois diferentes tipos de sistemas de aquecimento de piscinas: á gás natural e por bomba de calor elétrica. Foi realizada instrumentação em duas piscinas localizadas em uma mesma academia, cada uma delas dotada de um dos tipos de sistema de aquecimento. Além destas duas piscinas, que são objeto de investigação desta pesquisa, outras quatro piscinas, localizadas cada uma em um local distinto na cidade de São Paulo, também receberam instrumentação e a coleta de dados está sendo executada através de sistemas de aquisição de dados, para posterior análise e novos trabalhos de pesquisa. Como resultados da análise das duas piscinas, obteve-se um coeficiente de desempenho - COP, médio para o sistema de aquecimento por bomba de calor igual a 4. Para o sistema a gás natural, os resultados para a eficiência global do sistema indicaram 76%, ao passo que o rendimento apenas dos aquecedores foi de 82%. As análises dos dados permitiram comprovar a influência da temperatura ambiente sobre o COP da bomba de calor. Quanto menor a temperatura do ar, menor o COP. A Temperatura do ar também mostrou forte influência sobre o consumo de energia. / The aim of this research is to investigate the energetic performance of two distinct kinds of swimming pool heating systems: gas-fired and electric heat pump. A practical instrumentation research was prepared in these two indoor swimming pools, placed in the same location. Besides these, other four swimming pool, placed each in a different ambient in the city of São Paulo also received the instrumentation so that it will be possible to run future researches, once the data is already being collected by the data loggers installed. As a result of the data analysis, it was found that the average coefficient of performance of the heat pumps studied is 4. For the natural gas fired system, the global efficiency factor was found to be 76%. The efficiency of the heaters isolated was found to be 82%. This research showed that the COP of heat pump systems has strong correlation with the air temperature. The lower the air temperature, the lower the COP. Temperature also has strong influence on the consumption of energy.

Este trabalho é motivado pela constatação de que a instalação de sistemas de aquecimento de água a gases combustíveis nos apartamentos novos pode ter custos inferiores à instalação de sistemas elétricos e pelas perspectivas de aumento da oferta de gás natural no país. Considerando isso e a perspectiva de aumento no consumo de eletricidade, a pesquisa procura identificar barreiras para expansão do uso dos sistemas a gás, sugerindo formas para que sejam superadas. Considerando que as decisões tomadas durante a construção definem em grande medida os usos da energia nos imóveis, o trabalho se baseia numa pesquisa de campo desenvolvida por meio de entrevistas com agentes da construção civil. Inclui ainda uma contextualização sobre o uso da energia no setor residencial. Essa contextualização mostra a evolução do mercado brasileiro de gases combustíveis, a baixa participação histórica desses energéticos no aquecimento de água e as perspectivas de crescimento da oferta de gás natural no país. Também descreve o uso de água quente para banho, abordando os principais sistemas de aquecimento disponíveis no mercado paulistano. Perspectivas relativas ao aumento do consumo de eletricidade e de desenvolvimento do mercado imobiliário completam essa contextualização. A pesquisa mostra que já há ampla disseminação do uso de sistemas de aquecimento de água a gás na cidade de São Paulo. Esse desenvolvimento deveu-se a fatores como a obrigatoriedade da introdução de tais sistemas em alguns tipos de construção a partir de meados dos anos 1980, as exigências de conforto dos consumidores de classe média e classe alta e ao racionamento de eletricidade de 2001. Por outro lado, verifica-se que o chuveiro elétrico continua sendo usado nas construções voltadas para a classe baixa. Como esse é o segmento com maior demanda por novas residências, identifica-se um espaço importante para substituição de eletrotermia e aumento do uso dos gases combustíveis para aquecimento de água. / This research is motivated by the verification that the installation of gas based water-heating systems in new apartments may be cheaper than the use of electric systems. It is also motivated by the perspectives of a growing supply of natural gas in the country. Considering these points and the perspective of general growing use of electricity, this research identifies barriers to expand the use of gas based systems, suggesting ways to overcome those barriers. Considering that the energy uses in an apartment are largely affected by decisions taken during the construction of the building, the study is based on a field research developed through interviews with construction agents. It also includes a definition on the residential energy use, which details the gas (natural gas and LPG) market evolution, the historically reduced use of these fuels in water-heating systems, and the perspectives of rising supply of natural gas in Brazil. It also describes the use of hot water to hygiene, considering the main systems available in São Paulo. This context is completed by the perspectives related to the increase of electricity demand and the current real estate market development. The research concludes that gas based water-heating systems are already extensively used in São Paulo. This development is related to the mandatory use of those systems in some apartment configurations, the users demand for comfort, and the 2001 electric power shortage. On the other hand, it shows that electric showers are still largely used in building of poorer families. Since this segment has the largest demand for new houses in the country, there is space to substitute energy consumed for thermal purposes with the direct use of gas.

Este trabalho é motivado pela constatação de que a instalação de sistemas de aquecimento de água a gases combustíveis nos apartamentos novos pode ter custos inferiores à instalação de sistemas elétricos e pelas perspectivas de aumento da oferta de gás natural no país. Considerando isso e a perspectiva de aumento no consumo de eletricidade, a pesquisa procura identificar barreiras para expansão do uso dos sistemas a gás, sugerindo formas para que sejam superadas. Considerando que as decisões tomadas durante a construção definem em grande medida os usos da energia nos imóveis, o trabalho se baseia numa pesquisa de campo desenvolvida por meio de entrevistas com agentes da construção civil. Inclui ainda uma contextualização sobre o uso da energia no setor residencial. Essa contextualização mostra a evolução do mercado brasileiro de gases combustíveis, a baixa participação histórica desses energéticos no aquecimento de água e as perspectivas de crescimento da oferta de gás natural no país. Também descreve o uso de água quente para banho, abordando os principais sistemas de aquecimento disponíveis no mercado paulistano. Perspectivas relativas ao aumento do consumo de eletricidade e de desenvolvimento do mercado imobiliário completam essa contextualização. A pesquisa mostra que já há ampla disseminação do uso de sistemas de aquecimento de água a gás na cidade de São Paulo. Esse desenvolvimento deveu-se a fatores como a obrigatoriedade da introdução de tais sistemas em alguns tipos de construção a partir de meados dos anos 1980, as exigências de conforto dos consumidores de classe média e classe alta e ao racionamento de eletricidade de 2001. Por outro lado, verifica-se que o chuveiro elétrico continua sendo usado nas construções voltadas para a classe baixa. Como esse é o segmento com maior demanda por novas residências, identifica-se um espaço importante para substituição de eletrotermia e aumento do uso dos gases combustíveis para aquecimento de água. / This research is motivated by the verification that the installation of gas based water-heating systems in new apartments may be cheaper than the use of electric systems. It is also motivated by the perspectives of a growing supply of natural gas in the country. Considering these points and the perspective of general growing use of electricity, this research identifies barriers to expand the use of gas based systems, suggesting ways to overcome those barriers. Considering that the energy uses in an apartment are largely affected by decisions taken during the construction of the building, the study is based on a field research developed through interviews with construction agents. It also includes a definition on the residential energy use, which details the gas (natural gas and LPG) market evolution, the historically reduced use of these fuels in water-heating systems, and the perspectives of rising supply of natural gas in Brazil. It also describes the use of hot water to hygiene, considering the main systems available in São Paulo. This context is completed by the perspectives related to the increase of electricity demand and the current real estate market development. The research concludes that gas based water-heating systems are already extensively used in São Paulo. This development is related to the mandatory use of those systems in some apartment configurations, the users demand for comfort, and the 2001 electric power shortage. On the other hand, it shows that electric showers are still largely used in building of poorer families. Since this segment has the largest demand for new houses in the country, there is space to substitute energy consumed for thermal purposes with the direct use of gas.

Submitted by MATEUS DA SILVA TONON null (malphateus@hotmail.com) on 2016-12-14T18:24:10Z No. of bitstreams: 1 Dissertação.pdf: 5357617 bytes, checksum: 3b8314a11b9f377d4ce389642bf6d955 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-12-20T15:41:21Z (GMT) No. of bitstreams: 1 tonon_ms_me_ilha.pdf: 5357617 bytes, checksum: 3b8314a11b9f377d4ce389642bf6d955 (MD5) / Made available in DSpace on 2016-12-20T15:41:21Z (GMT). No. of bitstreams: 1 tonon_ms_me_ilha.pdf: 5357617 bytes, checksum: 3b8314a11b9f377d4ce389642bf6d955 (MD5) Previous issue date: 2016-10-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O Brasil apresenta um cenário propício à utilização em larga escala das chamadas energias renováveis, tanto das provenientes de fontes solares quanto das de fontes eólicas. Ressaltando, ainda, o uso da biomassa como outra alternativa nacional na produção de energia elétrica, em especial a produzida pela queima do bagaço da cana-de-açúcar. Há uma ampla possibilidade de utilização dos sistemas que aproveitam a energia solar de alguma forma, aplicáveis aos setores residencial, comercial ou industrial. O objetivo deste trabalho foi avaliar os impactos ocasionados pelos usos de sistemas fotovoltaicos e sistemas de aquecimento de água, tanto na conta de energia elétrica como no sistema elétrico em si, na região do Assentamento Estrela da Ilha, em Ilha Solteira – SP. Para tal, foi necessário realizar um levantamento das características de carga das residências presentes no local. A metodologia aplicada nas avaliações de retorno financeiro dos projetos foi escolhida de modo a proporcionar que sua aplicação possa ser realizada por qualquer pessoa que se interesse em avaliar a viabilidade de projetos semelhantes em suas residências ou quaisquer estabelecimentos. No levantamento das características de carga do local houve a divisão em três faixas de consumidores, separadas pelo consumo bruto mensal. A faixa de 0 à 200 kWh apresentou um fator de demanda de 0,0577, a de 200,01 à 400 kWh um de 0,1271 e a de 400,01 kWh ou mais um de 0,1540. Nas avaliações de retorno financeiro nenhum dos sistemas propostos apresentou atratividade em seu custo-benefício final. No estudo do impacto ocasionado pelo uso de painéis fotovoltaicos, no sistema de alimentação presente, não houve mudança significativa no perfil de tensão dos secundários dos transformadores, mesmo quando do uso de altos percentuais de geração fotovoltaica. Essa não mudança deve-se ao fato do sistema rural, em estudo, não apresentar uma grande concentração de consumidores conectados a um mesmo transformador e tampouco uma carga tão diversificada nas residências do local. / The Brazil present an auspicious scenery in the massive scale use of renewable sources, thus the derived for solar sources as for wind sources. Emphasizing the use of biomass like a national alternative in the electrical energy production, specially when produced by the burn of the bagasse for sugar cane. There are great potentialities in the use of systems than exploit the solar energy by anyway and applicables to residential, commercial and industrial sectors. The aim of this work was avaluate the impacts of the use of photovoltaic systems and solar water heating systems, thus in the electrical energy bill as in the electrical systems itself, in the zone of Assentamento Estrela da Ilha located in Ilha Solteira – SP. A load basic features making was realized in the residences belong in local. The applied metodology for financial return evaluation of the projects was selected for propitiate that its aplication could be realized by any people who has concern in evaluated the avaiability of similar projects in his residences or any other establishments. There are a division of the consumers in 3 streaks after the load basic features making, separated by the monthly consumption. The streak of 0 to 200 kWh presents a demand coefficient of 0.0577, in the streak of 200.01 to 400 kWh a demand coefficient of 0.1271 and the streak of 400.01 kWh or more a demand coefficient of 0.1540. The financial return evaluations shows that none of the systems had attractive when compared cost and final gains. The impact study of the use of photovoltaic panels in the existent electrical grid shows no significant changes in transformers secondary voltage levels even when used high perceptuals of photovoltaic generation. This result for the system analyzed be a rural one where there are low conected consumers concentration in a same transformer and few diversity of load in the local residences.

Orientador: Júlio Borges de Souza / Resumo: O Brasil apresenta um cenário propício à utilização em larga escala das chamadas energias renováveis, tanto das provenientes de fontes solares quanto das de fontes eólicas. Ressaltando, ainda, o uso da biomassa como outra alternativa nacional na produção de energia elétrica, em especial a produzida pela queima do bagaço da cana-de-açúcar. Há uma ampla possibilidade de utilização dos sistemas que aproveitam a energia solar de alguma forma, aplicáveis aos setores residencial, comercial ou industrial. O objetivo deste trabalho foi avaliar os impactos ocasionados pelos usos de sistemas fotovoltaicos e sistemas de aquecimento de água, tanto na conta de energia elétrica como no sistema elétrico em si, na região do Assentamento Estrela da Ilha, em Ilha Solteira – SP. Para tal, foi necessário realizar um levantamento das características de carga das residências presentes no local. A metodologia aplicada nas avaliações de retorno financeiro dos projetos foi escolhida de modo a proporcionar que sua aplicação possa ser realizada por qualquer pessoa que se interesse em avaliar a viabilidade de projetos semelhantes em suas residências ou quaisquer estabelecimentos. No levantamento das características de carga do local houve a divisão em três faixas de consumidores, separadas pelo consumo bruto mensal. A faixa de 0 à 200 kWh apresentou um fator de demanda de 0,0577, a de 200,01 à 400 kWh um de 0,1271 e a de 400,01 kWh ou mais um de 0,1540. Nas avaliações de retorno financeiro nenhum dos si... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre