Neste trabalho, o conceito de exergia é utilizado na proposição de um indicador de idade exergética que permita observar alterações da expectativa de vida de um indivíduo a partir da exergia destruída durante seu ciclo de vida. Para tal, a análise exergética é aplicada ao corpo humano e a volumes de controle menores dentro do corpo para diferentes cenários nos quais ocorram alterações nas reações metabólicas, a fim de determinar a taxa de exergia destruída em função da idade cronológica. Com essa informação, é calculado o indicador de idade exergética, podendo comparar a taxa de progressão da vida do indivíduo nas diferentes condições avaliadas com base na ideia de que há um valor máximo de exergia destruída acumulada durante a vida. Os efeitos do tabagismo e da obesidade são avaliados, e observa-se uma redução de aproximadamente 15 anos na expectativa de vida de fumantes, enquanto, para os obesos, o indicador mostra um aumento. Portanto, a identificação da obesidade como um fator de risco se deve ao desenvolvimento de patologias associadas à obesidade, e não ao aumento do metabolismo e à presença de gordura corporal subcutânea. Uma vez que maior parte das patologias relacionadas à obesidade está associada ao sistema cardiovascular, é proposto um modelo exergético do coração. Observa-se um aumento da taxa de exergia destruída na presença de hipertensão, que leva a uma redução de cerca de quatro anos na expectativa de vida. Por fim, é proposto um modelo do metabolismo de uma célula de câncer que leva em conta as alterações das rotas metabólicas, a partir do qual é possível observar um aumento de quase três vezes no metabolismo exergético de uma célula de câncer em comparação com uma célula saudável. A análise da progressão de um tumor indica que, na ausência de tratamento, a redução da expectativa de vida é de 27 anos. Além disso, no caso de tratamento, cada seis meses na presença da doença reduz a expectativa de vida em cerca de quatro anos. / In the present work, the concept of exergy is applied in order to propose an index of exergetic age that allows observing changes in life expectancy of a subject based on the exergy destruction throughout the life cycle. To do so, exergy analysis is applied to the human body and smaller internal control volumes for different scenarios where changes in metabolic reactions take place, aiming at determining the destroyed exergy rate as a function of chronological age. From this data, exergetic age index is calculated, enabling to compare the rate of life progression of the subject under different circumstances, based on the idea that there is a maximum value of cumulative destroyed exergy throughout life. The effects of smoking and obesity are evaluated and a reduction of approximately 15 years is observed for smokers, while, for obese people, the index shows an increase. Thus, the identification of obesity as a risk factor is more associated to the development of obesity-related diseases than to the metabolic rate increase and the presence of a thicker layer of subcutaneous fat. Since most of the obesity-related diseases are associated to the cardiovascular system, an exergy model of the human heart is proposed. The model reports an increase of the exergy destruction in case of hypertension that causes a reduction of about four years in life expectancy. Finally, a model of the metabolism of a cancer cell is proposed taking into account the changes in the metabolic paths, from which it is possible to observe a threefold increase of the exergy metabolism of a cancer cell, in comparison to a healthy one. The analysis of tumor progression indicates that, in the absence of treatment, the reduction of life expectancy is about 27 years. Furthermore, in case of treatment, each six months living with the disease causes a reduction of almost four years in life expectancy.

Made available in DSpace on 2016-12-23T14:08:16Z (GMT). No. of bitstreams: 1 Atilio Barbosa Lourenco.pdf: 1281099 bytes, checksum: 30b11e22aaae3c126ccd46522b08d45e (MD5) Previous issue date: 2012-12-13 / Este trabalho tem como objetivo apresentar uma abordagem termoeconômica alternativa cuja aplicação em ciclos de refrigeração deve isolar equipamentos dissipativos, como condensadores e válvulas, na estrutura produtiva de modo que os resultados gerados sejam coerentes. A abordagem, chamada de Modelo UFS, é baseada no conceito de desagregação da exergia física, no caso, em três componentes, a saber, termo de energia interna, termo de trabalho de fluxo e termo entrópico e é aplicada a cinco ciclos de refrigeração, a saber, ciclo reverso de Carnot, ciclo simples por compressão de vapor, ciclo multipressão por compressão de vapor em cascata, ciclo multipressão por compressão de vapor com interresfriamento e ciclo por absorção de simples efeito. Os balanços de custo são avaliados em nível dos componentes dos ciclos e os custos exergéticos unitários dos fluxos internos e do produto são obtidos. Também é feito o balanço de exergia e comparado com a diferença entre insumo e produto para cada unidade física dos ciclos, além da avaliação das razões produto-insumo. Os resultados mostram que os custos exergéticos unitários nunca são menores que a unidade e que as razões produto-insumo nunca são maiores que 100%, além da análise exergética gerar os mesmos valores de irreversibilidades que a diferença entre insumo e produto. Por fim, comentários são tecidos, bem como sugestões para trabalhos futuros / The goal of this work is to present an alternative thermoeconomic approach whose application to refrigeration cycles should isolate dissipative components, as condensers and valves, in the productive structure so the yielded results are consistent. The approach, called UFS Model, is based on the concept of physical exergy splitting into three components, namely, internal energy term, flow work term and entropic term and is applied to five refrigeration cycles, namely, Carnot s reverse cycle, vapor-compression simple cycle, vaporcompression cascade cycle, vapor-compression cycle with intercooling and simple-effect absorption cycle. The cost balances are assessed at the components level and the exergetic unit costs of both internal flows and plant product are obtained. Also, the exergy analysis is done and compared with the difference of fuel (or resource) and product of each physical unit, besides the assessment of the product-resource ratios. The results show that the exergetic unit costs are never less than one and the product-resource ratios are never greater than 100%. Besides, the exergy analysis yields same irreversibility values of the difference of resource and product. Finally, some remarks are done as well as suggestions for future works

O modelo brasileiro de geração de energia elétrica possui características muito peculiares em relação aos demais países do mundo. Seu vasto parque hidrelétrico possibilitou ao país utilizar indiscriminadamente a eletricidade em diversas formas de uso final. Porém, com a transição do modelo hídrico para um modelo misto de geração, surge um novo paradigma de eficiência energética. A eletricidade consumida em usos finais térmicos pode agora ser substituída por diferentes fontes energéticas de origem química, como o gás natural e a biomassa. Nesse novo cenário, a energia primária pode ser convertida tanto em energia elétrica, quanto em energia útil, na forma de calor. O objetivo desta pesquisa foi identificar a distorção presente no atual modelo energético nacional e avaliar o potencial de economia de energia primária possível de ser obtido pela substituição de eletricidade por fontes de origem química, em usos finais térmicos. A hipótese formulada é de que o uso racional da energia, segundo sua qualidade exergética e finalidade de uso, pode reduzir significativamente o consumo de energia primária. Para comprovar essa hipótese, foram realizadas estimativas de substituição de eletricidade por gás natural, nos usos finais térmicos de todos os setores de consumo. Além disso, foi realizada uma análise comparativa entre diversos países do mundo, quanto ao uso do calor em suas matrizes energéticas, a fim de estimar o percentual de eletricidade que poderia ser substituído no Brasil e a quantidade de energia química equivalente que seria demandada. Também foram estimados os possíveis ganhos ambientais decorrentes de tal substituição. Os resultados obtidos mostram a relevância do tema e o impacto que uma política de uso racional da energia poderia alcançar. / The electrical generation model of Brazil has a peculiar characteristic regarding other countries. Its large hydropower capacity allowed the indiscriminate use of the electricity for several kinds of end uses. However, with the transition of the hydroelectric generation model for a mixed generation model, a new paradigm of energy efficiency appears. The electricity consumed in the thermal end uses can be now substituted by other energy sources like natural gas and biomass. In that new scenario, the primary energy can be converted in electricity as well as useful energy. The objective was to identify the existent distortion in the current Brazilian model and to evaluate the economy potential of primary energy that could be obtained substituting the electricity by chemical energy in thermal end uses. The formulated hypothesis is that the rational use of energy, according to its exergy quality and purpose of use, can reduce significantly the primary energy consumption. The substitution of electricity by natural gas was simulated for all the thermal end uses of the energy mix. Besides, a comparative analysis taking into account other countries was carried out about the use of heat in the energy mixes, in order to estimate the electricity percent that could be substituted in Brazil and the equivalent amount of chemical energy that would be demanded. The possible environmental gains promoted by that substitution was also estimated. The results show the relevance of the theme and the impact that a policy of energy efficiency could attain.

A produção brasileira de frangos de corte evidenciou-se com o sistema de produção integrada, ao elevar a eficiência e a qualidade na conversão de proteína animal. Contudo, devido à rápida evolução tecnológica com crescente demanda energética e a diversificação dos sistemas de produção em diferentes microclimas, elucidar os processos de conversão de massa e energia tornou-se uma tarefa desafiadora neste sistema de produção. Constantemente, pesquisadores, produtores e agroindústria buscam processos mais rentáveis, reduzindo a demanda em mão de obra e o impacto ambiental. No entanto, nunca foi feita uma avaliação integrada do sistema produtivo de frangos de corte, considerando-se os aspectos quantitativos, energéticos e ambientais. Deste modo, o objetivo deste trabalho é promover um detalhado balanço de massa e energia, além de avaliar por meio da análise exergética, a qualidade das conversões de energia no processo produtivo de frangos de corte. Com o levantamento de insumos, produtos e rejeitos diretos, vinculados ao ciclo de produção, foram quantificadas as vazões mássicas para os diferentes processos do ciclo e, aplicando-se a avaliação exergética, obteve-se um diagnóstico completo da quantidade e qualidade energética envolvidas. Considerando o cenário adotado, em termos mássicos, as maiores demandas identificadas para os insumos foram a água (69,2%) e a ração (24,9%). Na saída do processo, os Gases de Efeito Estufa (GEE)/particulados extraídos através da ventilação (39,4%), os gases de combustão da lenha (25,6%) e a cama (14,2%) formam os principais rejeitos. A massa de frangos representa 20% das saídas. Foi identificado que a relação entre o consumo de água e ração é função da temperatura. Em termos energéticos, as maiores contribuições identificadas para os insumos foram a ração (77,7%) acompanhada do material absorvente (9,7%) e da lenha (9,6%). Na saída do processo lideram as energias associadas aos frangos (33,2%) e da cama gerada (32,1%). O rendimento energético obtido para galpões convencionais foi de 27%. Os processos que mais destroem exergia dentro do ciclo produtivo são a formação da cama de frangos a partir das excretas (51,5% em convencionais e 48,2% em climatizados) e a combustão da lenha para aquecimento (21,9% em convencionais e 20,5% em climatizados). Além disso, foi estimado o rendimento de Segunda Lei para o ciclo próximo de 26%. Foram introduzidos os índices energético e exergético de produção permitindo a comparação entre diferentes sistemas. Como principal resíduo, a cama de frangos gerada no ciclo, quando reutilizada como insumo para aquecimento do próprio aviário na forma de briquetes, pode elevar as eficiências. Comparando-se as demandas médias para as duas formas de aquecimento, foi constatado que o uso do GLP é mais favorável ao ambiente se comparado à lenha, devido à forma direta de transferência de calor aos frangos. É aconselhável, em dias quentes, elevar a velocidade do ar, utilizando o resfriamento evaporativo somente em casos de elevada temperatura ambiente, pois a introdução de água eleva a exergia dissipada no ciclo. / Brazilian production of broilers has been highlighted with the implantation of the integrated production system, which improved the efficiency and quality in animal protein conversion. However, due to the rapid technological evolution with the increasing energy demand and the diversification of production systems in different microclimates, elucidating mass and energy conversion processes has become a challenging task regarding this production system. Constantly, researchers, producers and agribusiness look for more profitable processes, reducing the labour demand and environmental impact. However, an integrated evaluation of the productive system of broilers, considering the quantitative, energy and environmental aspects has never been carried out. Thus, this study aims at promoting a detailed mass and energy balance and to evaluate the quality of the energy conversions in the productive process of broilers by means of exergy analysis. With the survey of inputs, products and direct wastes, linked to the production cycle, the mass flow rates for the different processes of the cycle were quantified and a complete diagnosis of the quantity and quality energetic involved was obtained applying the exergy evaluation. Considering the scenario adopted, in mass terms, the greatest demands identified for the inputs were water (69.2%) and feed (24.9%). At the exit of the process, the greenhouse gases/dust extracted through ventilation (39.4%), the firewood combustion gases (25.6%) and the litter poultry generated (14.2%) are the main outputs. The broilers mass was quantified in 20%. The relation between water and feed consumption has shown to be the temperature. Regarding energy, the largest contribution identified for the inputs was feed (77.7%) followed by the absorbent (9.7%) and firewood (9.6%). At the exit of the process lead the energy associated with the broilers (33.2%) and the poultry litter generated (32.1%). The energy performance obtained for conventional shed was 27%. The processes of the largest exergy destroyed within the productive cycle are the litter poultry converted from excreta (51.5% in conventional and 48.2% in air conditioning) and the combustion of wood for heating (21.9% in conventional and 20.5% in air conditioning). In addition, the second law performance for the cycle was estimated in about 26%. The energy and exergy production index was introduced allowing for the comparison among different systems. As the main residue, the litter poultry generated in the cycle when reused as an input for heating the aviary itself in the form of briquettes, can increase these efficiencies. The use of LPG is more environmentally friendly compared to wood, considering the average demands for the too forms of heating, due to the direct form of heat transfer to the broilers. It is advisable, on hot days, to raise the air speed using the evaporative cooling only in cases of high ambient temperature, as the introduction of water raises the exergy dissipated in the cycle.

Processos de refinação de petróleo caracterizam-se pelo intenso consumo energético. Dentre as mais variadas operações presentes nesta indústria, a separação de correntes por torres de destilação apresenta posição de destaque, despendendo mais de 40% da energia gasta por uma refinaria. Plantas de separação de propeno, importante produto para a indústria petroquímica visando a produção de polipropileno, se enquadram neste sentido, requerendo torres de destilação de considerável uso energético. Apesar da grande rejeição de calor referente a este consumo, por apresentar baixo nível térmico associado, frequentemente não se observa o seu aproveitamento. Neste contexto, bombas de calor apresentam-se como excelente alternativa para recuperação energética de correntes de rejeito térmico, com vastos exemplos na literatura aplicados à indústria e, especificamente associados a torres de destilação. Neste trabalho avaliou-se, por meio de modelagem e simulação computacional, a aplicação de duas modalidades de bomba de calor em ciclo de compressão de vapor (compressão de topo e compressão do fundo despressurizado), e uma em ciclo de absorção, integradas a uma planta de separação de propeno de uma refinaria localizada no Brasil, comparativamente a uma planta equivalente utilizando processo de destilação convencional com refervedor de fundo e condensador de topo. Para as premissas definidas no trabalho, verificou-se como o melhor resultado, a aplicação da bomba de calor por compressão de vapor de topo da coluna de destilação, o qual demonstra que 4,1 MW associado ao trabalho de eixo do compressor, torna possível uma economia energética de mais de 80% do consumo de vapor dágua e água de resfriamento, se comparados à planta convencional, sem a utilização de bomba de calor. Cálculos de rendimento exergético demonstram a melhor configuração ser 2,4 vezes mais eficiente que o modelo convencional. Limitações de troca térmica foram observadas no estudo de caso da bomba de calor de compressão de fundo despressurizado, demandando uma recirculação adicional de propano ao ciclo, com consequente redução de rendimento exergético a um patamar intermediário entre o caso convencional e o melhor resultado observado. Já para a bomba de calor de absorção, verificou-se, para o fluido de trabalho praticado e condição simulada, resultado aquém da situação convencional. Por fim, avalia-se que a aplicação de fonte térmica alternativa (vapor sub-atmosférico), de baixo conteúdo exergético, ainda que de difícil obtenção junto à refinaria, poderia viabilizar a inversão dos resultados observados, recomendando a sua verificação de uso para estudos futuros. / Oil refining process are recognized by its very intense energy consumption. In this industry, distillation columns are extensively used for product separation. Contributing with more than 40% of refinery energy consumption, distillation units typically require high level of heat rejection, frequently not capable of being directly used, due to its low temperature profile. In this scenario, the distillation of propylene, important product for petrochemical industry is set as one of the most energy intense refinery process. Process integration using heat pumps are considered an excellent choice to provide waste heat upgrade, with numerous examples applied to industry and specifically for distillation towers cited in the literature. In this work, two different vapor compression heat pump cycles (tower overhead compression and bottom flash compression) and an absorption heat pump cycle were applied to a propylene distillation facility located at a Brazilian refinery, in a comparison analysis with a conventional distillation process with typical bottom reboiler and overhead condenser. Considering the defined basis, the overhead vapor compression scheme has shown the better result, since its shaft compressor work of 4.1 MW, integrated to the tower allows reducing more than 80% of steam and cooling water consumption originally associated. An exergetic analysis was performed, confirming the proposal scheme to be 2.4 times more efficient than the process without heat pump integration. An intermediate result, between the conventional distillation and associated overhead vapor compression heat pump was observed in the bottom flash case, since, as consequence of a heat exchange bottlenecking, an additional propane compression loop had to be applied. With regards to the absorption heat pump scheme, considering the chosen fluid and the plant work conditions, no advantage was observed in comparison to the conventional case. In time, an alternative utility (vacuum steam), with low exergy content, was applied to the conventional system, replacing the low pressure steam originally used. Besides its difficult practical application, the alternative utility has proved to be able to reverse the previous work results, thus, further studies are recommended regarding its viability of use.

Biomass is an attractive renewable energy resource for electricity generation, which has the potential to protect air quality, reduce dependence on fossil fuel, and improve forest health. Biomass gasification is a technology that transfers solid or liquid biomass into gaseous energy carrier (syngas) to increase the efficiency of electricity generation. The objective of this thesis is to supply a detailed feasibility study and provide a state-of-the-art economical pathway on biomass gasification application. The work of this dissertation can be separated into two parts: commercial-scale biomass integrated gasification combined cycle (BIGCC) power plants comparison and other biomass gasification system design. The first part compares eight BIGCC systems with three groups of technology variations of gasification agent, syngas combustion method, and CO2 capture and storage. By comparing on performance, economic, and environmental indicators of these systems, it is found that BIGCC systems have higher exergy efficiency and lower emissions than biomass combustion electricity production system and electricity grid. However, its levelized cost of electricity is around 27% higher than the average electricity market price. To reduce the BIGCC system’s cost, in the second part of this thesis, the potential for waste material gasification has been discussed. This part discussed the tire gasification and the gasification technology application for avian influenza poultry management. Results showed that tire gasification has a lower cost than natural gas which has the potential to reduce the BIGCC system’s cost. Moreover, gasification is an effective and economical available approach for avian influenza poultry management.

<p>The wallpaper company Duro Sweden AB, one of the most important Scandinavian</p><p>wallpaper manufacturers, wants to decrease its energy use and costs and make its</p><p>production more environmentally friendly. It implies changes in the key process energy</p><p>use whom consists mainly by drying process using heat production from oil.</p><p>The purpose of this project, studied by the consulting company Sweco Theorells AB,</p><p>is to determine the feasibility of a change in the energy utilisation implemented to the</p><p>most representative process to propose future solutions’ basis on the future energy</p><p>question.</p><p>The company use mainly two kind of energy, electricity with 1055MWh per year and</p><p>oil with 1985MWh per year. The oil power consumption and cost represent respectively</p><p>65% and 73% of the global part.</p><p>Several proposed changes with better energy efficiency are presented : use of district</p><p>heating as a heat source, Infrared Drying, combination, etc; but due to the important</p><p>rebate make by the Swedish government on the oil price, they are not currently viable to</p><p>achieve.</p><p>But the constant rise of the oil price could be sooner a strong incentive to make these</p><p>improvals, strongly environmentaly friendly and power consumption reducer,</p><p>economicaly viable in the long term.</p>

In this thesis, an experimental research is conducted on scroll-based Organic Rankine Cycle (ORC) focusing on the expansion process. An important feature of the ORC is the ability to utilize low or moderate temperature heat sources derived from renewable energy such as concentrated solar radiation, biomass/biofuels combustion streams, geothermal heat and waste heat recovery. The ORC is more appropriate than steam Rankine cycle to generate power from low capacity heat sources (5-500 kW thermal). For example, expansion of superheated steam from 280oC/1000 kPa to a pressure corresponding to 35oC saturation requires a volume ratio as high as 86, whereas for the same operating conditions toluene shows an expansion ratio of 6 which can be achieved in a single stage turbine or expander. The objective of this work is to experimentally study the performance of a selected refrigeration scroll compressor operating in reverse as expander in an ORC. To this purpose, three experimental systems are designed, built and used for conducting a comprehensive experimental programme aimed at determining the features of the expansion process. In preliminary tests the working fluid utilized is dry air while the main experiments are done with the organic fluid R134a. Experimental data of the scroll expander are collected under different operating conditions. Power generation in various conditions is analyzed in order to determine the optimum performance parameters for the scroll expander. In addition, thermodynamic analysis of the system is conducted through energy and exergy efficiencies to study the system performance. Based on the experimental measurements, the optimum parameters for an ORC cycle operating with the Bitzer-based expander-generator unit are determined. The cycle energy and exergy efficiencies are found 5% and 30% respectively from a heat source of 120oC. / UOIT

This thesis is concerned with the thermodynamic analyses of ion and proton-conducting solid oxide fuel cells (SOFC) fed with ammonia and urea as fuels. A multi-level approach was used to determine the feasibility and the performance of the fuel cells. First, the cell-level thermodynamics were examined to capture the effect of various operating parameters on the cell voltage under open-circuit conditions. Second, electrochemical studies were conducted to characterize the cell-level performance under closed-circuit conditions. Third, the fuel cells were individually integrated in a combined-cycle power generation system and parametric studies were performed to assess the overall performance as well as the thermal and exergy efficiencies. The findings of this study showed that the overall performance and efficiency of the ammonia fed SOFC is superior in comparison to that of the urea fed counterpart. In particular, the ammonia fed system combined with proton-conducting SOFC achieved a thermal efficiency as high as 85% and exergy efficiency as high as 75%. The respective efficiencies of the ammonia fed system combined with ion-conducting SOFC were lower by 5-10%. However, the urea fed system combined with ion or proton-conducting SOFC demonstrated much lower performance and efficiencies due to higher thermodynamic irreversibilities. / UOIT

Sustainable development is a growing concern for inhabitants of the planet earth. Consumption of fossil sources keeps up the depletion of nature’s capital and causes environmental impacts. One solution to have a sustainable society is to reduce the dependency on fossil fuels and substitute them by renewable energy sources. Among different types of renewable energy, biofuels have great potential for development and improvement. Though, the production of biofuels is criticized by many experts from the energy efficiency, environmental and economical points of view. Biogas as one type of first generation biofuels is achieved from the wastes and by-products of other industries, and can be used as a transportation fuel in the form of biomethane. The use of by-products may give added value as inputs to the biogas production process, a process which may be called "upcycling." The aim of upcycling is to convert wastes into new materials with higher quality or higher environmental value in order to reduce the consumption of raw materials which results in decreasing of energy usage and environmental impacts The aim of this thesis is to study the possibility of a biogas plant to act as an upcycler of wastes and by-products through anaerobic digestion process by the use of exergy analysis and economic evaluation. An imaginary biogas plant which uses a major by-product of brewing industry, i.e. Brewer’s Spent Grain (BSG), is considered to quantify the added value by biogas production process. The results of the exergy analysis show that the exergy of the input BSG (78,320 MJ) is upgraded into two main products as biomethane (47,430 MJ) and biofertilizer (37,026 MJ) with a total exergy amount of 84,456 MJ. On the other hand, the economic analysis of the studied biogas production process indicates that the biogas plant has the added value for the input material. In the economic analysis, the annual costs and benefits of the biogas production is calculated. The results show that the production of biomethane and biofertilizer from the by-product of brewing industry is profitable. However, the price of input BSG and also the variation price of the biofertilizer in different seasons, have great impact on the economy of a biogas plant. The outcomes from exergy and economic analysis are indicated that the biogas production process is an "upcycling" process which has the added value for the inputs, from both economic and quality points of view. The exergy and economic evaluation may be used as indicators of the sustainable development, but only increasing the exergy and the economic value of a production process alone should not be considered as the sustainability of a system.