<p>Air conditioning, space heating, and refrigeration account for approximately 40% of the electricity usage in the U.S. residential and commercial building sector. To improve energy utilization and reduce energy consumption in space conditioning applications, advanced heat pumping technologies are needed. The chemical looping heat pump (CLHP) is a promising thermodynamic cycle that has shown the potential to achieve a cooling coefficient of performance (COP_c) increase of over 20% relative to conventional vapor compression (VC) systems.</p> <p><br></p> <p>The overarching goal of this study is to evaluate the chemical looping heat pump concept for residential applications, including thermodynamic potential, as well as technical and economic feasibility before developing and deploying a pilot scale system. The evaluation process includes advanced thermodynamic modeling for better assessments of working fluids and systems, techno-economic analysis for initial cost assessment of the scaled-up system, and small-scale experiments for proof-of-concept.</p> <p><br></p> <p>A working fluid screening process was developed to identify suitable working substance pairs for CLHP systems. The key metrics for evaluating the working fluids are associated with the possibility of phase change after a chemical reaction, reversible cell potential and power consumption, and cooling capacity of the system. Such metrics were applied to several fluids to assess their suitability. It was found that isopropanol/acetone working substances showed the highest cooling capability for a given power consumption. Even though this approach was applied to particular organic fluids (e.g., alcohols and ketones), this analysis can be generalized to other single-component fluids, multi-component fluids, and several chemical designs.</p> <p><br></p> <p>A modeling framework to estimate operating cost, capital cost, and levelized cost of energy was developed to enable a direct early-stage comparison of a CLHP with conventional VC systems. The models were helpful in understanding the influence of key factors such as efficiency, unit utilization (annual cooling and heating delivered, kWh_t/yr), and price of electricity ($/kWh_e) with the goal of determining target markets for initial CLHP products. The LCOE of CLHP could be less than that of VC in the case of high utilization (≥  20,000 kWh_t) with high performance improvements (COP_CLHP/COP_VC = 1.3) even though the capital cost of the CLHP is nearly 1.5-2 times higher than VC.</p> <p><br></p> <p>The key process of a CLHP cycle, which is electrochemically driven phase transformation, was experimentally demonstrated based on the advanced test rig and electrochemical cell. A polymer electrolyte membrane flow cell with a self-fabricated membrane electrode assembly and flow channels was employed to drive the reaction. The breakdown voltage analysis indicates that ohmic and mass transfer overpotentials account for more than 90% irreversibilities of the reactions. In addition, the results showed the possibility of phase transition of 20-30% at current density of ~0.003 A/cm² and the cell voltage of 0.025 V. The extent of a chemical reaction can be further improved by increasing the current and reducing the flow rate.</p> <p><br></p> <p>A semi-empirical cycle model was leveraged to predict realistic system performance. The model includes an electrochemical cell model with other component models in a CLHP cycle. The Second law efficiency was 50% of the Carnot limit with a cooling capacity of 2.24 mW (cooling density of 1.6 W/m²) at sink temperature of 40 °C  and source temperature of 23 °C. The cause for the precipitous drop in COP_c with increasing current density was overpotential, which requires further research on the optimization of membrane and catalytic materials as well as a geometry of flow channels to minimize the losses. Higher efficiency can theoretically be achieved at an elevated fluid temperature as long as an electrochemical cell can achieve a greater degree of conversion.</p> <p><br></p> <p>There are several challenges that should be reconciled in a future operational device and cycle at scale. Additional research on both material- and system-level performance is indispensable to meet practical size requirements. Nevertheless, this study is intriguing in terms of the possibility of developing a high efficiency device with the ability to use more environmentally friendly working fluids. Broadly, this CLHP research can contribute to accelerating the development of the newly emerging field, which is thermal systems coupled with electrochemical processes, that can maximize system efficiency using low-GWP fluids.</p>

No description available.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-11T13:33:08Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Lucas A. Freitas - 2016.pdf: 2716743 bytes, checksum: 81ec501b7ac3258c32ab8676d9ab5774 (MD5) / Made available in DSpace on 2017-04-11T13:33:08Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Lucas A. Freitas - 2016.pdf: 2716743 bytes, checksum: 81ec501b7ac3258c32ab8676d9ab5774 (MD5) Previous issue date: 2016-09-05 / CAPES / Estão inseridos na proposta deste trabalho dois objetivos: o primeiro consiste na realização de levantamento e caracterização do consumo de energia elétrica dos shopping centers de Pernambuco; o segundo tem por _nalidade aplicar uma metodologia de decisão econômica que permite avaliar a melhor con_guração de um sistema térmico para o atendimento das demandas de frio e energia elétrica dos shopping centers. O procedimento de otimização busca minimizar o VPL (Valor Presente Líquido) do sistema e, para isso, utiliza-se de um método híbrido composto por quatro passos: proposta do sistema genérico, pré-seleção dos equipamentos, busca exaustiva e Programação Linear. A otimização considera aspectos técnicos e econômicos, tais como: curvas de demandas de energia, tarifas em base horária, rendimentos e custos dos equipamentos proporcionais às potências. A _m de verificar o quão robusto é o sistema base foram consideradas algumas variáveis econômicas como, por exemplo, a variação da tarifa de combustível, variação da tarifa de energia elétrica, custo de aquisição do motogerador de eletricidade, variação da taxa de câmbio (dólar/real), além do estudo da variação da demanda em horário de ponta. Ainda, foi de_nido, para cada parâmetro estudado, um fator de variabilidade de 50% - 200%. O sistema se mostrou muito sensível a mudanças nas tarifas energéticas, para as quais suportou uma redução de apenas 9% na tarifa de gás natural, ou, ainda, um aumento de 12% na tarifa de energia elétrica. Para taxa cambial e o custo inicial do motogerador, as variações suportadas foram de 26% e 24% respectivamente. Já no que se refere à variação da demanda em horário de ponta, o sistema suportou um aumento de 70%. / They are included in the proposal of this work two objectives: the _rst is to carry out survey and characterization of the electricity consumption of the shopping malls of Pernambuco; the second on implementing an economic decision methodology to evaluate the best con_guration of a thermal system to meet the demands of cold and power of shopping malls. The optimization procedure seeks to minimize the NPV (Net Present Value) of the system and, therefore, we use a hybrid method consists of four steps: proposed generic system, pre-selection of equipment, exhaustive search and Linear Programming. The optimization considers technical and economic aspects, such as energy demand curves, tari_ on hourly basis, e_ciencies and costs in proportion to the power equipment. In order to check how robust is the base system were considered some economic variables such as, for example, the change in fuel price, change in electricity tari_, cost of purchase of electricity power generator, exchange rate variation (dollar / real), and the demand variation study in peak hours. Still, it was de_ned for each parameter studied, a variability factor of 50% - 200%. The system was too sensitive to changes in energy prices, for which bore a decrease of only 9% in the gas rate , or even a 12% increase in electricity tari_. For exchange rate and the initial cost of the motor generator, supported changes were 26% and 24% respectively. In what regards the variation of demand peak time, the system supported a 70% increase.

The first part of diploma thesis describes how to measure the parameters of solar thermal collector and solar thermal system. The computational part analyzes heat consumption in the evaluated building and describes design of the solar thermal system for domestic hot water. Last part focuses on the energy assessment of the designed solar system above and evaluation of the solar system, which is located at the Faculty of Civil Engineering in BUT.

The main theme of the master's thesis is using of thermal camera to measure temperatures in electrical engineering. First are mentioned the physical principles of heat transfer. Then the thesis deals with methods of determining the correct emissivity of the measured object and in the next point with sensors designed for sensing infrared radiation, there is also part dedicated to evaluation software Report Sat Standard, which was used to evaluate the pictures taken with thermal camera SAT-HY 6800. Next part of this work is the measurement of the DC and EC motor with help of thermocamera, which took place in the electric company ATAS Nachod. Attachment to this master's thesis there is animation of EC motor created in Autodesk Inventor.

The food industry is a large consumer of industrial energy. A very large portion of this energy is needed in the form of thermal energy at medium to low temperatures. Fossil fuels remain the dominant sources of this energy. This combination provides various possibilities to reduce energy consumption and CO2 emissions with heat recovery, but also with the integration of solar process heat. Energy efficiency must provide the context, or background, of such considerations, and is therefore a very important aspect of them. It is a complex task to design an efficient heat supply with a variety of energy sources. An analysis of standards for energy audits, guides for energy efficiency and guides for solar process heat integration confirms that complexity. However, no available methodology considers all the necessary steps. These must range from analysis of the existing heat supply to the redesign of an efficient heat supply system. The focus must be on heat sources with waste heat and on solar process heat that might be used to complement the conventional sources. The design of a process heat system is mainly the task of design engineers in engineering offices. Specific tools and measures are needed to support these experts. However, the companies of the food industry sector employ their own energy engineers for energy issues. These people are actually the decision makers responsible for the configuration of the company energy supply systems, who also possess knowledge of the processes in their industry subsector. The expertise of the energy engineers varies within a broad range and is also connected to their area of responsibility. Therefore, it is important to consider these energy engineers when developing a methodology. The development of the methodology proposed herein consists first of the configuration of the tools and measures, which were assigned to four elements and functions. Second, the methodology so developed was applied at two companies in cooperation with their energy engineers, in detailed case studies. The feedback from the energy engineers is therefore a main objective and provides a background for evaluation of the usability of the methodology. It demonstrates the expertise required of the energy engineers, for the application of the tools and measures provided. Moreover, the development and application of the methodology involving real companies demonstrates the necessity of getting feedback from energy engineers. That finding is very important, and has been insufficiently considered in previous guides or methodologies. It is proposed that further work be aimed at providing additional case studies to extend the use of this methodology to other parts of the food industry.

The master’s thesis deals with technologies for energy utilisation of waste with annual treatment capacity approximately from 10 to 50 kt/year and their application in regions of the Czech Republic. In the first part of the thesis the results of heat consumption analysis in seven regions of the CR are introduced while in two selected regions a production of waste was analyzed too. The main part deals with the design of technological solution of waste-to-energy plant with medium capacity and its integration to specific conditions of the two selected regions. Alternatives of combined heat supply were assessed from waste-to-energy plant as well. A basic economic analysis that contains the estimates of incomes and capital expenditures and operating expense is a part of this thesis too.

No description available.

A preocupação energética tem impulsionado a humanidade a buscar alternativas sustentáveis de energia. Neste contexto, os edifícios de escritórios têm um papel importante, em especial, devido ao elevado consumo de energia dos sistemas de condicionamento de ar. Para esses sistemas, a possibilidade de utilização de energia solar é uma alternativa tecnicamente possível e interessante de ser considerada, principalmente porque, quando a carga térmica do edifício é mais elevada, a radiação solar também é mais elevada. Dentre os sistemas de condicionamento de ar solar, o sistema térmico - que associa coletores solares térmicos com chiller de absorção - é o mais disseminado, na atualidade. Entretanto, dependendo do caso, outras tecnologias podem ser vantajosas. Uma opção, por exemplo, no caso de edifícios de escritórios, é o sistema elétrico - que associa painéis fotovoltaicos ao chiller convencional de compressão de vapor. Neste trabalho, para um edifício de escritórios de 20 pavimentos e 1000 m2 por pavimento, na cidade de São Paulo, no Brasil, duas alternativas de ar condicionado solar tiveram seus desempenhos energéticos analisados: o sistema térmico - com coletores solares térmicos somente na cobertura e o sistema elétrico - com painéis FV somente nas superfícies opacas das fachadas. Para isso, com o software EnergyPlus do Departamento de Energia dos Estados Unidos obteve-se as carga térmica atuantes no edifício e com a aplicação do método de cálculo de consumo de energia dos sistemas de ar condicionado solar, proposto pelo Projeto SOLAIR da União Européia, adaptado para a realidade da pesquisa, obteve-se o desempenho energético dos sistemas. Os resultados mostraram que, para o edifício de 20 pavimentos, o sistema elétrico tem o melhor desempenho energético, economizando 28% e 71% da energia elétrica que consumiria um sistema de ar condicionado convencional, em um dia de verão e de inverno, respectivamente. O sistema térmico, ao contrário, apresentou um desempenho energético ruim para o edifício estudado, consumindo, por exemplo, em um dia de verão, cerca de 4 vezes mais energia elétrica do que um sistema de ar condicionado convencional. Constatouse que isso ocorreu, pois a área coletora limitada à cobertura foi insuficiente para atender a demanda do chiller de absorção, que passou a operar com frações solares baixas, da ordem de 50% e 20%, de pico, no dia de inverno e de verão, respectivamente. Assim, constatou-se que para que o sistema térmico apresente um desempenho energético satisfatório é preciso que o edifício não seja tão alto. De fato, os resultados mostraram que somente se o edifício tivesse no máximo 2 pavimentos, o sistema térmico teria um desempenho energético melhor do que um sistema convencional. No caso de ser aplicado ao edifício térreo de 1000m2 de área, por exemplo, esse sistema economizaria aproximadamente 65% da energia elétrica do sistema convencional. Por fim, constatou-se também que o desempenho energético do sistema térmico seria elevado com a otimização da área e da tecnologia de coletores solares, com o aprimoramento do sistema de aquecimento auxiliar e com a redução da carga térmica do edifício por meio de técnicas passivas de climatização. / Energy concern has driven human kind to seek sustainable energy alternatives. In this context, office buildings have an important role, especially due to the high energy consumption of air conditioning systems. For these systems, the possibility of using solar energy is technically feasible and interesting to be considered, mainly because generally when the building thermal load is higher, the solar radiation is also higher. Among solar airconditioning systems, the thermal system - which combines solar collectors with absorption chiller - is the most widespread, nowadays. However, depending on the case, other technologies may take advantage. One option, for example, in the case of office buildings, is the electrical system - which combines photovoltaic panels with conventional vapor compression chiller. In this work, an office building of 20 floors with 1,000 m2 floor area, in Sao Paulo, Brazil, two technologies of solar air conditioning had their performance analyzed: the thermal system - presenting solar thermal collectors only on the roof and the electrical system with PV panels only on the opaque surfaces of the facades. For this, the software EnergyPlus of the United States Department of Energy obtained the building thermal load and the with the solar air conditioning energy consumption calculating method proposed by SOLAIR project of the European Union and adapted to this work, energy performance of systems was obtained. The results showed that for this building, the electrical system had the best energy performance, saving 28% and 71% of electricity that would consume a conventional air conditioning system in a summer day and a winter day, respectively. The thermal system, in contrast, showed a poor energy performance, consuming, for example, on a summer day, about four times more electricity than a conventional air conditioning system. It was found that this occurred because the collectors area limited to the roof of the building was insufficient to meet the absorption chiller demand, causing low solar fractions in the operation, of around 50% and 20% peak, in a winter day and in a summer day, respectively. Thus, in order of provide a satisfactory energy performance, the thermal system requires that the building not to be so tall. In fact, the results showed that only if the building had up to two floors, the system would perform better than a conventional system. In case of be installed in a building with the ground floor only, and floor area of 1000m2, for example, this system would save about 65% of the electricity comparing to a conventional system. Finally, it was found that this energy performance would be elevated as well with the optimization of solar collectors area and technology, with auxiliary heating system improvement and with the reduction of thermal load of the building by means of passive air conditioning techniques.

A preocupação energética tem impulsionado a humanidade a buscar alternativas sustentáveis de energia. Neste contexto, os edifícios de escritórios têm um papel importante, em especial, devido ao elevado consumo de energia dos sistemas de condicionamento de ar. Para esses sistemas, a possibilidade de utilização de energia solar é uma alternativa tecnicamente possível e interessante de ser considerada, principalmente porque, quando a carga térmica do edifício é mais elevada, a radiação solar também é mais elevada. Dentre os sistemas de condicionamento de ar solar, o sistema térmico - que associa coletores solares térmicos com chiller de absorção - é o mais disseminado, na atualidade. Entretanto, dependendo do caso, outras tecnologias podem ser vantajosas. Uma opção, por exemplo, no caso de edifícios de escritórios, é o sistema elétrico - que associa painéis fotovoltaicos ao chiller convencional de compressão de vapor. Neste trabalho, para um edifício de escritórios de 20 pavimentos e 1000 m2 por pavimento, na cidade de São Paulo, no Brasil, duas alternativas de ar condicionado solar tiveram seus desempenhos energéticos analisados: o sistema térmico - com coletores solares térmicos somente na cobertura e o sistema elétrico - com painéis FV somente nas superfícies opacas das fachadas. Para isso, com o software EnergyPlus do Departamento de Energia dos Estados Unidos obteve-se as carga térmica atuantes no edifício e com a aplicação do método de cálculo de consumo de energia dos sistemas de ar condicionado solar, proposto pelo Projeto SOLAIR da União Européia, adaptado para a realidade da pesquisa, obteve-se o desempenho energético dos sistemas. Os resultados mostraram que, para o edifício de 20 pavimentos, o sistema elétrico tem o melhor desempenho energético, economizando 28% e 71% da energia elétrica que consumiria um sistema de ar condicionado convencional, em um dia de verão e de inverno, respectivamente. O sistema térmico, ao contrário, apresentou um desempenho energético ruim para o edifício estudado, consumindo, por exemplo, em um dia de verão, cerca de 4 vezes mais energia elétrica do que um sistema de ar condicionado convencional. Constatouse que isso ocorreu, pois a área coletora limitada à cobertura foi insuficiente para atender a demanda do chiller de absorção, que passou a operar com frações solares baixas, da ordem de 50% e 20%, de pico, no dia de inverno e de verão, respectivamente. Assim, constatou-se que para que o sistema térmico apresente um desempenho energético satisfatório é preciso que o edifício não seja tão alto. De fato, os resultados mostraram que somente se o edifício tivesse no máximo 2 pavimentos, o sistema térmico teria um desempenho energético melhor do que um sistema convencional. No caso de ser aplicado ao edifício térreo de 1000m2 de área, por exemplo, esse sistema economizaria aproximadamente 65% da energia elétrica do sistema convencional. Por fim, constatou-se também que o desempenho energético do sistema térmico seria elevado com a otimização da área e da tecnologia de coletores solares, com o aprimoramento do sistema de aquecimento auxiliar e com a redução da carga térmica do edifício por meio de técnicas passivas de climatização. / Energy concern has driven human kind to seek sustainable energy alternatives. In this context, office buildings have an important role, especially due to the high energy consumption of air conditioning systems. For these systems, the possibility of using solar energy is technically feasible and interesting to be considered, mainly because generally when the building thermal load is higher, the solar radiation is also higher. Among solar airconditioning systems, the thermal system - which combines solar collectors with absorption chiller - is the most widespread, nowadays. However, depending on the case, other technologies may take advantage. One option, for example, in the case of office buildings, is the electrical system - which combines photovoltaic panels with conventional vapor compression chiller. In this work, an office building of 20 floors with 1,000 m2 floor area, in Sao Paulo, Brazil, two technologies of solar air conditioning had their performance analyzed: the thermal system - presenting solar thermal collectors only on the roof and the electrical system with PV panels only on the opaque surfaces of the facades. For this, the software EnergyPlus of the United States Department of Energy obtained the building thermal load and the with the solar air conditioning energy consumption calculating method proposed by SOLAIR project of the European Union and adapted to this work, energy performance of systems was obtained. The results showed that for this building, the electrical system had the best energy performance, saving 28% and 71% of electricity that would consume a conventional air conditioning system in a summer day and a winter day, respectively. The thermal system, in contrast, showed a poor energy performance, consuming, for example, on a summer day, about four times more electricity than a conventional air conditioning system. It was found that this occurred because the collectors area limited to the roof of the building was insufficient to meet the absorption chiller demand, causing low solar fractions in the operation, of around 50% and 20% peak, in a winter day and in a summer day, respectively. Thus, in order of provide a satisfactory energy performance, the thermal system requires that the building not to be so tall. In fact, the results showed that only if the building had up to two floors, the system would perform better than a conventional system. In case of be installed in a building with the ground floor only, and floor area of 1000m2, for example, this system would save about 65% of the electricity comparing to a conventional system. Finally, it was found that this energy performance would be elevated as well with the optimization of solar collectors area and technology, with auxiliary heating system improvement and with the reduction of thermal load of the building by means of passive air conditioning techniques.