[pt] O presente trabalho tem por objetivo analisar e comparar sistemas de trigeração (produção simultânea de eletricidade, aquecimento e refrigeração) de diferentes arquiteturas com base nas eficiências energética e exergética e nas emissões de CO2. Sistemas de trigeração são considerados mais eficientes na conversão de energia, se comparados a sistemas convencionais, devido ao reaproveitamento do calor de rejeito do motor térmico para outros fins (aquecimento, acionamento de chiller, ou geração de eletricidade). Quatro configurações (com chiller de compressão de vapor, com chiller de absorção, com a combinação dos ciclos anteriores, e combinado com um ciclo Rankine orgânico) foram estudadas a partir de modelos matemáticos resultantes dos balanços de energia e de exergia, e do cálculo de emissão de CO2 considerando as demandas energéticas (eletricidade, aquecimento e refrigeração) como independentes do desempenho do sistema. Todas as arquiteturas de trigeração aqui analisadas apresentaram um ponto ótimo de operação, onde o calor de rejeito recuperado para aquecimento se iguala à respectiva demanda. Neste ponto, o fator de utilização de energia (indicador de desempenho pela primeira Lei) e a eficiência exergética são máximos, e a emissão de CO2, mínima. A solução das equações resultantes mostrou também que a melhor arquitetura, do ponto de vista energético, exergético ou ambiental, dependerá da combinação das demandas energéticas. / [en] The present work aims at analyzing and comparing trigeneration systems (for the simultaneous production of electricity, heating and refrigeration) of different architectures based on energetic and exergetic efficiencies and on CO2 emissions. Trigeneration systems are regarded as more efficient in energy conversion, if compared to conventional systems, due to the recovery of waste heat from the heat engine. The waste heat is used for different purposes, including heating, chiller driving or electricity generation. Four trigeneration configurations (with vapor compression chiller, absorption chiller, with a combination of the two previous cycles, or combined with an organic Rankine cycle) were studied. Mathematical models resulting from the energy and exergy balances and from the calculation of CO2 emissions were developed taking into account that the three energy demands (electricity, heating and refrigeration) are independent from the trigeneration system performance. Solution of the resulting equations indicated an optimal point of operation, for all trigeneration architectures under study, where the waste heat recovered for heating equals the heating demand. At this point, the energy utilization factor (first Law indicator) and the exergy efficiency reach their maximum value, and the CO2 emissions, its lowest. Another important finding is that the configuration with best performance, from the energetic, exergetic, or environmental point of view, will depend on how the energy demands relate to each other.

[pt] A produção simultânea de energia elétrica, calor e frio, a partir da queima de combustível primário (trigeração), pode se mostrar como estratégia promissora do ponto de vista energético e de projeto, principalmente em indústrias como a química e a de alimentos. No presente trabalho descreve-se o estudo experimental de um sistema de produção de água gelada (chiller) com compressor hermético acionado eletricamente. Um motor a combustão interna, do tipo Diesel, foi convertido para operar com gás natural veicular (Diesel- gás) e aciona um gerador de eletricidade que supre a energia elétrica necessária ao funcionamento do chiller e ao atendimento de demanda elétrica préestabelecida. O resultante sistema de trigeração é, portanto, composto por dois sub-sistemas: a bomba de calor (chiller) e o conjunto motorgerador. Calor de rejeito, do condensador do chiller e do sistema de arrefecimento e gases de exaustão do motor, é recuperado para a produção de água quente. O sistema é analisado à luz da 1ª e 2ª leis da Termodinâmica. As razões entre as demandas de frio, calor e eletricidade, as temperaturas de evaporação e de condensação da bomba de calor, e a razão de substituição de óleo Diesel por gás natural veicular são os principais parâmetros de controle dos resultados apresentados. Determinou-se, para o sistema em questão, uma taxa de substituição energética ótima do óleo Diesel por GNV de aproximadamente 25%, com uma economia de 11% a 15% (para geração de potência elétrica acima de 4,0 kW), fundamentada na diferença de preços entre os dois combustíveis e numa melhora do rendimento do motor para estas condições de operação. Obteve-se a contribuição percentual de cada um dos produtos energéticos (frio, calor e eletricidade), em função do consumo de combustível, para as diferentes potências testadas, em função da taxa de substituição energética do óleo Diesel por GNV. Determinou-se, experimentalmente, a vazão de água nos diferentes componentes, para a qual se obtém uma máxima eficiência do sistema, quando analisado do ponto de vista exergético. / [en] The simultaneous production of electric energy, heat and cooling capacity from the primary fuel burning on a heat engine (trigeneration) can emerge as a promising strategy, from the energy and project points of view, mostly, in food and chemistry industries. The present work describes the experimental study of a vapor compression system for chilled water production. A Diesel internal combustion engine was converted to operate with natural gas (Diesel-gas) and drives an electric generator that supplies the necessary electric energy for the chiller`s functioning and to attend the pre-established electric demand. The resultant system of trigeneration is, therefore, composed of two subsystems: the heat pump (chiller) and the engine-generator group. Heat rejected from the condenser of chiller and from the cooling system and exhaust gases of the engine, is recovered for hot water production. The system is analyzed under the light of first and second laws of the Thermodynamics. The ratio between the cooling, heating and electricity demands, the temperatures of evaporation and condensation of the heat pump, and the Diesel-natural gas substitution ratio are main parameters of control of the presented results. The percentile contribution of cold, heat and electricity (on energetic fuel consumption basis), for the different electric energy generation rates, was obtained as a function of the energy substitution rate of the Diesel oil for natural gas. An optimal energy substitution rate of Diesel oil for natural gas of approximately 25% was determined with an economy rated between 11% and 15% (for electric energy generation rates above 4,0 kW), based both on the difference between prices of the two fuels and on the engine`s performance improvement for these operational conditions. An optimum water flow rate, from the exergetic point of view, was found for each component.

Rostoucí světová poptávka po méně efektivních zdrojích energie vede ke zvýšení zájmu o kogenerační technologie v sektoru domácností. Pomocí této technologie lze významně snižovat množství znečišťujících látek emitovaných při výrobě elektřiny a tepla pro domácnosti. Kogenerační systémy v sektoru domácností nabízí možnost produkce jak užitného tepla a elektřiny z jednoho zdroje paliva, např. motorové nafty či zemního plynu. Tato práce se zaměřuje na analýzu možností užití kogeneračních a tri-generačních technologií ke zlepšení efektivity využití primárního zdroje energie, zejména v zemích severní Afriky. První část práce se orientuje na obecné definice v oblasti elektroenergetiky, aktuální i budoucí výhled energetické bilance v Libyi. Následující kapitoly se věnují kogeneračním a tri-generačních systémům, jejich charakteristikám se zaměřením na technické parametry, výhodám a nevýhodám těchto systémů a jejich dalšímu rozvoji. Hlavní část práce se zabývá problematikou spotřeby typických rodinných domů ve třech nejdůležitějších městech Libye. Dále předkládá citlivostní analýzu, která je zaměřená na výpočet množství energie vyžadované k pokrytí energetických potřeb typického domu (vytápění, ohřev vody a klimatizace) a porovnání naplnění těchto potřeb při uvažování technických a ekonomických hledisek. Výsledky práce budou využity pro tvorbu pokladů pro Libyjské energetické úřady.

Despite the fact that cogeneration (CHP) and tri-generation (CHCP) are among the most efficient ways to produce electricity and thermal energy, there is still some unexploited potential for these techniques. One could say that the circumstances for using these techniques are better now than ever. Some of the reasons for applying CHP and CHCP are: the techniques are well understood, their application could generate some profit, and the required technology is available. Moreover, there is increasing concern in regards to energy security, the need to increase the energy efficiency in power generation and distribution as well as to lower the emissions from fossil fuel combustion. CHP/CHCP promoters and developers face difficulties when analyzing the conditions and proposing a plan of application. On one hand, there are some external barriers which have to be torn down by means of energy regulation schemes. These may include economic incentives, easy and safe interconnection to the grid to export electricity and have backup if necessary, and access to the market to sell the surplus of electricity at a fair price. On the other hand, there are some internal barriers such as the difficulty evaluating potential energy savings, emission reduction, and economic performance of a project based on the circumstances of a specific site; lack of awareness; unwillingness to invest in CHP/CHCP projects; and difficulty in selecting and sizing the equipment which would give the maximum benefits in terms of life cycle cost, energy savings and emission reduction. Nowadays, it is possible to develop software tools which use simulations and optimization algorithms to evaluate several options, compare them and chose the ones that give the optimum performance with respect to an objective function defined by the user. In this project, the general context for the application of cogeneration and tri-generation projects was studied including factors which have an impact on its feasibility and performance. Moreover, a survey of the exiting feasibility analysis tools was done, and a case study was chosen and analyzed. Next, a model was developed using the software Trnsys for the simulation and Matlab for the optimization. The model was tested by evaluating the study case. The result of the simulation and optimization gives several possible equipment size combinations. The tradeoff between two different objective functions such as net present value and primary energy savings or emission reduction is presented in Pareto front diagrams. The main conclusion of this project is that by using Trnsys and Matlab, it is possible to develop more complex models which, when applying optimization algorisms, could become a very useful and helpful tool that CHP/CHCP developers could use to speed up the analysis of projects while contributing to the goal of deploying these techniques.

Made available in DSpace on 2014-12-17T14:57:39Z (GMT). No. of bitstreams: 1 IldefonsoMS.pdf: 1793001 bytes, checksum: 8b7c737ca595a5f30c4e9de306d3fe97 (MD5) Previous issue date: 2007-06-27 / The generation for termoeletricity is characterized as a solid process of conversion of thermal energy (heat) in electric without the necessity of mobile parts. Although the conversion process is of low efficiency the system presents high degree of trustworthiness and low requisite of maintenance and durability. Its principle is based on the studies of termogeneration carried through by Thomas Seebeck in 1800. The frank development of the technologies of solid state for termoeletricity generation, the necessity of the best exploitation of the energy, also with incentive the cogeneration processes, the reduction of the ambient impact allies to the development of modules semiconductors of high efficiency, converge to the use of the thermoeletric generation through components of solid state in remote applications. The work presents the development, construction and performance evaluation of an prototype, in pilot scale, for energy tri-generation aiming at application in remote areas. The unit is composed of a gas lamp as primary source of energy, a module commercial semiconductor for thermoelectric generation and a shirt for production of the luminosity. The project of the device made compatible a headstock for adaptation in the gas lamp, a hot source for adaptation of the module, an exchanger of to be used heat as cold source and to compose first stage of cogeneration, an exchanger of tubular heat to compose second stage of cogeneration, the elaboration of a converter dc-dc type push pull, adequacy of a system of acquisition of temperature. It was become fullfilled assembly of the prototype in group of benches for tests and assay in the full load condition in order to evaluate its efficiency, had been carried through energy balance of the unit. The prototype presented an electric efficiency of 0,73%, thermal of 56,55%, illumination of 1,35% and global of 58,62%. The developed prototype, as the adopted methodology of assay had also taken care of to the considered objectives, making possible the attainment of conclusive results concerning to the experiment. Optimization in the system of setting of the semicondutor module, improvement in the thermal insulation and design of the prototype and system of protection to the user are suggestions to become it a commercial product / A gera??o por termoeletricidade caracteriza-se como um processo s?lido de convers?o de energia t?rmica (calor) em el?trica sem a necessidade de partes m?veis. Embora o processo de convers?o seja de baixa efici?ncia o sistema apresenta alto grau de confiabilidade e baix?ssimos requisitos de manuten??o e durabilidade. Seu princ?pio ? baseado nos estudos de termogera??o realizados por Thomas Seebeck em 1821. O franco desenvolvimento das tecnologias de estado s?lido para gera??o de termoeletricidade, a necessidade do melhor aproveitamento da energia, inclusive com incentivo a processos de cogera??o, a redu??o do impacto ambiental aliados ao desenvolvimento de m?dulos semicondutores de alta efici?ncia, convergem para o uso da gera??o termoel?trica atrav?s de componentes de estado s?lido em aplica??es remotas. O trabalho apresenta o desenvolvimento, constru??o e avalia??o de performance de um prot?tipo, em escala piloto, para tri-gera??o de energia visando aplica??o em ?reas remotas. A unidade ? composta de um lampi?o a g?s combust?vel como fonte prim?ria de energia, um m?dulo semicondutor comercial para gera??o termoel?trica e uma camisa para produ??o da luminosidade. O projeto do dispositivo compatibilizou um cabe?ote para adapta??o no lampi?o, uma fonte quente para adapta??o do m?dulo, um trocador de calor para ser utilizado como fonte fria e compor o 1? est?gio de cogera??o, um trocador de calor tubular para compor o 2? est?gio de cogera??o, a elabora??o de um conversor cc-cc tipo push pull, adequa??o de um sistema de aquisi??o de temperatura. Realizou-se a montagem do prot?tipo em bancada para testes e ensaio na condi??o de carga plena a fim de avaliar a sua efici?ncia, sendo realizado balan?o de energia da unidade. O prot?tipo apresentou uma efici?ncia el?trica de 0,73%, t?rmica de 56,55%, de ilumina??o de 1,35% e global de 58,62%. O prot?tipo desenvolvido, como tamb?m a metodologia de ensaio adotada atenderam aos objetivos propostos, possibilitando a obten??o de resultados conclusivos acerca do experimento. Otimiza??o no sistema de fixa??o do m?dulo semicondutor, melhoramento na isola??o t?rmica e design do prot?tipo e sistema de prote??o ao usu?rio s?o sugest?es para torn?-lo um produto comercial

L'objectif des travaux présentés dans ce mémoire concerne le développement d'un modèle global représentant le couplage de l'enveloppe du bâtiment avec les équipements énergétiques. Une approche systémique appelée les Bond Graphs, peu employée jusqu'ici dans la modélisation des systèmes thermiques, est utilisée. Le modèle global du bâtiment, regroupant sous le même environnement de simulation, les modèles de l'enveloppe du bâtiment, les apports solaires, les émetteurs de chauffage et de rafraîchissement et le système de ventilation, est développé pour reconstituer l'ensemble des articulations énergétiques entre l'enveloppe et les environnements intérieur et extérieur. A travers la modélisation d'un bâtiment multizone, le couplage systémique des modèles de l'enveloppe et des apports solaires est présenté. Par ailleurs, un système combinant un plancher chauffant et un plafond rafraîchissant est étudié à l'aide des modèles des émetteurs de chauffage et de rafraîchissement. Le renouvèlement d'air dans le bâtiment est également concerné par la modélisation Bond Graph. Enfin, des éléments de validation expérimentale sont présentés. Pour cela, la plateforme de tri-génération d'énergie ENERBAT est exploitée. L'objectif est d'étudier le couplage optimal enveloppe du bâtiment - équipements énergétiques pour lequel les modèles BG sont développés. Une étude paramétrique tenant compte des interactions entre les paramètres étudiés est menée sur un projet réel de rénovation. Finalement, une combinaison appropriée des paramètres étudiés a été retenue afin de réduire la consommation énergétique selon la réglementation thermique française (RT2012) / Our works focus on the setting of reliable tools able to analyze the interaction between the building envelope and HVAC systems. The developed approach is based on Bond Graphs methodology, a graphical modeling language which is particularly suitable for energy exchanges. A numerical model gathering, under the same simulation environment, sub-models representing the building envelope, the solar gains, the floor heating, the chilled ceiling and the ventilation system, is developed in order to predict the energy interactions between these sub-systems. The multi-zone building model is developed in order to simulate and analyze the overall building thermal behavior. Then, the solar gains model is also included to predict the solar radiation exchanges in a way close to reality. The model of the heating and cooling system, combining the floor heating and the chilled ceiling, is developed in order to improve the thermal comfort of the building. Afterwards, the ventilation system is modeled in order to represent the air exchange inside the building. The experimental validation is carried out on the tri-generation unit integrated with a thermal solar system (platform ENERBAT). Furthermore, the parametrical study was realized in order to gain a better understanding according to the impact of some factors in the energy performance of the single-family building located in Meurthe-et-Moselle region (France). Optimization of several measures, such as insulation of the building envelope, type of glazing, building orientation and ventilation system, is performed to respond to the requirements of the French thermal standard (RT2012)