<div>Plug-in hybrid electric vehicles (PHEVs) are being considered as an alternative to conventional medium-duty (MD) and heavy-duty (HD) commercial vehicles to reduce fuel consumption and tailpipe emissions. Lithium ion batteries, which are used in PHEVs due to their high energy density, are expensive. The battery contributes significantly towards the life-cycle cost of MD/HD PHEVs, as these vehicles, due to high mass and aggressive battery usage, require multiple battery replacements over their lifetime. Smaller batteries increase the fuel consumption and need more replacements, while bigger batteries increase the initial system cost. Powertrain design from a life-cycle cost perspective is required to explore this trade-off and maximize the economic gains obtained from PHEVs. </div><div><br></div><div>Powertrain design entails component sizing, control strategy selection as well as architecture selection. Different powertrain designs yield different lifetime economic gains. A variety of applications exist for MD/HD vehicles, which differ in their ways of powertrain usage, due to variations in required acceleration, available braking, and average and maximum speeds. Therefore, different powertrain designs are needed depending on the application and usage scenario. The powertrain design space needs to be explored, and solutions that maximize the economic gains within the specified constraints need to be chosen.</div><div><br></div><div>This dissertation compares the economic viability of two PHEV applications (MD Truck and HD Transit Bus), with options of series and parallel hybrid architectures, over multiple drivecycles, for four economic scenarios (years 2015, 2020, 2025 and 2030). It is shown that hybridizing the transit bus achieves payback sooner than hybridizing the truck. Further, the results for the transit bus application, over the Manhattan drivecycle, show that implementation of the parallel architecture is economically viable in the 2015(present) scenario, while the series architecture becomes viable in 2020, due to significantly lower initial costs involved in the parallel architecture.</div><div><br></div><div>A methodology to select a solution out of the explored design space that maximizes the economic gains is demonstrated. Variations in the economic and vehicle usage conditions for which this solution is designed, can be expected. It is therefore necessary to check the robustness of this solution to change in external factors such as vehicle mass, annual vehicle miles travelled (AVMT), component and fuel costs. It is shown that the economic gains are affected by the battery cost, fuel cost, AVMT and vehicle mass, while the number of battery replacements are affected by AVMT and vehicle mass. </div><div><br></div><div>A probability-based approach is demonstrated to obtain confidence in the economic and battery life predictions. Specifically, probability-based variations are provided to variables such as miles traveled between recharge, recharge C-rate and battery temperature. It is shown that battery life is affected the most by battery temperature.</div><div><br></div><div>A battery heating/cooling system is required to maintain constant battery temperature of operation during all seasons, but these systems incur additional fuel costs. A framework that utilizes just the Coefficient of Performance (COP) of the heating/cooling system to calculate the excess fuel cost is proposed and demonstrated. An increase of 0.9-1.8\% in fuel consumption is shown, depending on the drivecycle and ambient temperature.</div><div><br></div><div>Further, the well-to-wheel (WTW) fuel-cycle emissions from conventional and PHEV transit buses operating in Indiana and California are assessed using the ``Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation'' (GREET) Model 2017, developed by Argonne National Labs. It is shown that 59% and 63% greenhouse gas (GHG) reductions can be achieved in Indiana and California respectively, along with reduction in carbon monoxide (CO), nitrogen oxides NOx, particulate matter with diameter less than 2.5 microns PM2.5 and volatile organic compounds (VOC) emissions for both the states. However, an increase in sulfur oxides SOx emissions for both the states, and particulate matter with diameter less than 10 microns PM10 increase for Indiana, are observed. </div><div><br></div>

A manutenção das matrizes suínas fora da zona de conforto térmico compromete o seu desempenho, em especial no período lactacional, devido a redução no consumo voluntário de ração e na produção de leite. O estresse por calor é um desafio devido a dificuldade da espécie em dissipar calor, tendo como principal alternativa o uso da respiração para perder calor em situações de alta temperatura. Alternativas estruturais, como ventilação, gotejamento, resfriamento de piso e uso de processo evaporativo adiabáticos servem para amenizar as perdas produtivas. O objetivo do estudo foi analisar a influência de três sistemas de ambiência utilizando as variáveis temperatura e umidade relativa do ar, sobre os aspectos produtivos de fêmeas suínas e suas leitegadas. Foram utilizadas 244 fêmeas, em três tratamentos e três repetições. Ambiente climatizado - AC (n= 79), temperatura da sala de maternidade controlada por um sistema de resfriamento evaporativo adiabático, associado à ventilação negativa; Ar sobre as fêmeas - ASF (n= 82), saída individual de ar refrigerado sobre as fêmeas associado ao manejo de cortinas; Manejo de cortinas - MC (n= 83). Nas matrizes foi avaliado; o peso, a espessura de toucinho (ET), o escore corporal visual (ECV) pós-parto e ao desmame, e o intervalo desmame-estro (IDE) e o consumo médio diário de ração (CMR) na lactação. Dos leitões foi registrado o peso na uniformização, aos 14 dias e ao desmame. As mínimas e máximas diárias das variáveis temperatura e umidade relativa do ar (UR) foram mensuradas, bem como calculados as médias destas. As variáveis foram analisadas pelo procedimento GLM. As médias foram comparadas pelo teste de Tukey-Kramer, com nível de 5% de significância. A temperatura média observada no tratamento AC (23,0ºC) foi inferior e a UR (88,5%) superior quando comparada as dos demais. Para o CMR foi observada uma interação significativa entre os tratamentos e as repetições avaliadas. Na primeira repetição, o CMR foi maior no AC do que no MC. Na segunda repetição, não houve diferença entre os sistemas e, na terceira, os três sistemas diferiram entre si, com o maior CMR sendo observado no AC e o menor no MC. Apesar disso não foram observadas diferenças com relação a perda de peso lactacional e IDE. No entanto, o peso dos leitões ao desmame no AC (6164,2 g) foi semelhante aos demais, enquanto no ASF (6205,5 g) foi superior ao MC (5970,2 g). O tratamento ambiente climatizado foi efetivo em diminuir a temperatura ambiente, sendo uma alternativa para prover conforto térmico às fêmeas lactantes. No tratamento AC, o consumo de ração pelas fêmeas foi maior em uma das repetições, mas os leitões dos tratamentos AC e ASF tiveram desempenho semelhante e o primeiro não diferiu do MC, provavelmente por terem mobilizado mais energia para a manutenção da temperatura. / Maintaining sows outside the zone of thermal comfort compromises their performance, especially during lactation, mainly due to reductions in voluntary feed intake and milk production. The heat stress is a challenge because of the difficulty of the sow to dissipate heat with the main alternative use of breathing to lose heat in situations of high temperature. Structural alternatives, such as ventilation, drip, cooling and floor using adiabatic evaporative cooling to mitigate losses arising productive. This study analyzes the influence of three different cooling systems on the productivity of sows and their litters using the variables temperature and relative humidity. Two hundred and forty-four females were divided into three treatment and three replication groups: air-conditioned - AC (n = 79), with farrowing house temperature controlled by a system of adiabatic evaporative cooling combined with negative ventilation; snout cooler - SC (n = 82), with a cold air outlet directed towards females, combined with management of curtains; and management of curtains - MC (n = 83). The following variables were assessed for all sows: weight, backfat thickness (BFT), and visual body condition score (BCS), postpartum and at weaning, as well as weaning-to-estrus interval (WEI) and average daily feed intake (ADFI) during lactation. Piglet weight was recorded at cross-fostering, after 14 days, and at weaning. Minimum and maximum daily temperatures and relative humidity (RH) were measured and averaged. Variables were analyzed using the GLM procedure and means were compared using the Tukey-Kramer test at the 5% level of significance. Lower temperature averages were found for the AC treatment (23.0°C) and higher for RH (88.5%) than for others. There was significant interaction between treatment and evaluation periods for ADFI. In the first period, ADFI was higher in the AC group than in the MC one. In the second, there was no difference between the systems, while the three systems differed significantly in the third, with the largest ADFI found in AC and the lowest in MC. Yet there were no differences with respect to lactation weight loss and WEI. However, piglet weight at weaning in the AC group (6164.2g) was lower than in the SC (6205.5g) and higher than in the MC (5970.2g). The air-conditioned room treatment was effective in decreasing the temperature, and an alternative to provide thermal comfort to the lactating. In the air-conditioned room treatment, feed intake by females was higher in the replications, but the piglets from treatments air-conditioned room and snout cooler were similar and not different from the first management of curtains, probably because they had mobilized more energy to maintain temperature.

Industrial and military vehicles, including trucks, tanks and others, employ cooling systems that address passenger cooling and auxiliary cooling loads ranging from a few Watts to 50 kW or more. Such systems are typically powered using vapor-compression cooling systems that either directly supply cold air to the various locations, or cool an intermediate single-phase coolant closed loop, which in turn serves as the coolant for the passenger cabins and auxiliary loads such as electronics modules. Efforts are underway to enhance the performance of such systems, and also to develop more light weight and compact systems that would remove high heat fluxes. The distributed cooling configuration offers the advantage of a smaller refrigerant system package. The heat transfer between the intermediate fluid and air or with the auxiliary heat loads can be fine tuned through the control of flow rates and component sizes and controls to maintain tight tolerances on the cooling performance. Because of the additional loop involved in such a configuration, there is a temperature penalty between the refrigerant and the ultimate heat sink or source, but in some configurations, this may be counteracted through judicious design of the phase change-to-liquid coupled heat exchangers. Such heat exchangers are inherently smaller due to the high heat transfer coefficients in phase change and single-phase liquid flow compared to air flow. The additional loop also requires a pump to circulate the fluid, which adds pumping power requirements. However, a direct refrigerant-to-heat load coupling system might in fact be suboptimal if the heat loads are distributed across large distances. This is because of the significantly higher pressure drops (and saturation temperature drops) incurred in transporting vapor or two-phase fluids through refrigerant lines across long plumbing elements. An optimal system can be developed for any candidate application by assessing the tradeoffs in cooling capacity, heat exchanger sizes and configurations, and compression, pumping and fan power. In this study, a versatile simulation platform for a wide variety of direct and indirectly coupled cooling systems was developed to enable comparison of different component geometries and system configurations based on operating requirements and applicable design constraints. Components are modeled at increasing levels of complexity ranging from specified closest approach temperatures for key components to models based on detailed heat transfer and pressure drop models. These components of varying complexity can be incorporated into the system model as desired and trade-off analyses on system configurations performed. Employing this platform as a screening, comparison, and optimization tool, a number of conventional vapor-compression and distributed cooling systems were analyzed to determine the efficacy of the distributed cooling scheme in mobile cooling applications. Four systems serving approximately a 6 kW cooling duty, two with air-coupled evaporators and two with liquid-coupled evaporators, were analyzed for ambient conditions of 37.78°C and 40% relative humidity. Though the condensers and evaporators are smaller in liquid-coupled systems, the total mass of the heat exchangers in the liquid-coupled systems is larger due to the additional air-to-liquid heat exchangers that the configuration requires. Additionally, for the cooling applications considered, the additional compressor power necessitated by the liquid-coupled configuration and the additional power consumed by the liquid-loop pumps result in the coefficient of performance being lower for liquid-coupled systems than for air-coupled systems. However, the use of liquid-coupling in a system does meet the primary goal of decreasing the system refrigerant inventory by enabling the use of smaller condensers and evaporators and by eliminating long refrigerant carrying hoses.

The thesis explores the technical feasibility of an alternative method of decoupling air-conditioning systems function within the context of ecological issues. The system is a variant of dedicated outdoor air systems to separate dehumidification and cooling in air conditioning equipment. The project specifically investigates locating these components within the building envelope. Placement in the envelope moves the systems closer to fresh air and offers architectural expression for components that are normally out of sight. Designers, engineers, building science, mechanical, structural, biologist, and architectural engineers ideally as agents offer beneficial improvement to the system. The reduction in size of components into the building envelope offers risk. The thesis design space uses historical works, biological analogues, and past work to ground the technical understanding of the topic. Specific use of biological inspired design realizes translation from other systems to improve the alternative decoupled air conditioning system. The thesis develops prototype models for lighting analysis and for sensible and latent heat calculations. Psychrometric charts serve as tools to understand the thermodynamic air-conditioning process in conventional direct expansion vapor compression and solar liquid desiccant air conditioning systems. Data, models, and sketches provide tools for improvements to the 'thick' building envelope. Finally, the diagrams translate into functional decompositions for modifications to improve the system. The thesis probes the constraints in the areas of cost, fabrication, and technology that may not yet exist for selective improvement rather than a barrier to development of the thesis.

Submitted by JORGE ANDRES ARROYAVE ORTEGON (jaarroyaveo@unal.edu.co) on 2018-08-20T15:11:59Z No. of bitstreams: 1 Dissertação_Jorge_Arroyave_Versão_Final_FC(1).pdf: 6142009 bytes, checksum: 185f73f2530ec7bc30607d8a9e004919 (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-08-20T20:10:47Z (GMT) No. of bitstreams: 1 arroyaveortegon_ja_me_ilha.pdf: 6142009 bytes, checksum: 185f73f2530ec7bc30607d8a9e004919 (MD5) / Made available in DSpace on 2018-08-20T20:10:47Z (GMT). No. of bitstreams: 1 arroyaveortegon_ja_me_ilha.pdf: 6142009 bytes, checksum: 185f73f2530ec7bc30607d8a9e004919 (MD5) Previous issue date: 2018-04-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A energia solar pode ser aproveitada como fonte de energia térmica para aquecimento de água, por exemplo, em coletores solares ou como fonte de energia elétrica usando sistemas de células fotovoltaicas. Entretanto, as células fotovoltaicas, geralmente, de custos relativamente altos, têm algumas restrições relacionadas a altas temperaturas de operação e distribuições de temperatura não homogêneas levando a redução da vida útil e eficiência elétrica de tais sistemas. Essas limitações têm sido o foco de pesquisas, a fim de melhorar as eficiências elétricas, regular as temperaturas de operação e reduzir os materiais necessários para fabricação das células. Assim, este projeto de pesquisa tem como objetivo avaliar o desempenho de um dissipador de calor, baseado em microcanais retangulares paralelos, no resfriamento de uma célula fotovoltaica de alta concentração (HCPV-High Concentration Photovoltaic Cell), utilizando-se de análise teórica (modelo térmico), simulação numérica (usando o software comercial CFD ANSYS® Fluent v15) e de uma bancada experimental. Neste trabalho, foram consideradas as condições de máxima radiação (denominado de pior cenário, quando a célula não gera eletricidade e todo o calor deve ser dissipado) e de radiação média ao longo do período considerado. Os dados climatológicos foram obtidos do site Canal Clima - UNESP, com dados historicos do clima na região noroeste paulista. Foi realizada uma revisão do estado da arte a fim de compreender como os sistemas de geração elétrica fotovoltaica podem ser otimizados pelo uso de concentradores solares e materiais mais eficientes (células de junção-múltipla). A influência da temperatura nestes sistemas e como sistemas de resfriamento podem melhorar seu desempenho também foram analisados. Uma bancada experimental permitiu validar os resultados teóricos e numéricos obtidos. Comprovou-se que o uso de dissipador de calor baseado em microcanais pode permitir um controle efetivo da temperatura da célula HCPV, melhorando sua eficiência de conversão de energia solar em energia elétrica. O dissipador de calor foi avaliado sob condições de fluxo de calor constante, variando-se a velocidade mássica, G, no intervalo de 300 kg/m2s a 1500 kg/m2s. Assim, foi possível manter a superfície da célula a uma temperatura de 40°C, aproximadamente, para uma queda de pressão de, em média, 6 kPa. Os resultados das três análises apresentaram comportamentos similares e a concordância entre eles foi razoável, considerando as limitações de cada abordagem. / Solar energy can be used as a source of thermal energy in solar collectors, for example, or as a source of electricity using photovoltaic cell systems. However, photovoltaic cells requires high investments having some restrictions related to high operating temperatures and nonhomogeneous temperature distributions, leading to a reduction in the useful life and electrical efficiency. These limitations have been the focus of researches in order to improve electrical efficiencies, to regulate operating temperatures, and to reduce required materials in the cells. Thus, this research project aims to evaluate the performance of a heat sink based on parallel rectangular microchannels for cooling of a high concentration photovoltaic cell (HCPV), using theoretical analysis (thermal model), numerical simulation (using commercial software CFD ANSYS® Fluent v15) and an experimental bench. In this work, it was considered the conditions of maximum radiation (named worst scenario, when the cell does not generate electricity and all the heat must be dissipated) and the average radiation over the period considered. These climatological data were obtained from the Canal Clima – UNESP site, in the northwestern region of São Paulo state. A review on the subject was carried out in order to understand how solar photovoltaic systems can be optimized using solar concentrators and more efficient materials (multiple-junction cells). The influence of temperature and cooling systems were analyzed. An experimental bench was built, which allowed the validation of the theoretical and numerical results. The use of microchannel heat sinks can allow an effective temperature control of the HCPV cell, improving its efficiency of converting thermal energy into electrical energy. The heat sink was evaluated for different heat flux values and for mass velocity, G, in a range of 300 kg/m2s to 1500 kg/m2s. It was possible to maintain the high concentration cell at 40 °C with a pressure drop of 6 kPa, for the worst scenario. The three analyzes presented similar behavior and the agreement between them was reasonable, considering the approaches limitations. / FAPESP 2013/15431-7 / CNPq 458702/2014-5

A manutenção das matrizes suínas fora da zona de conforto térmico compromete o seu desempenho, em especial no período lactacional, devido a redução no consumo voluntário de ração e na produção de leite. O estresse por calor é um desafio devido a dificuldade da espécie em dissipar calor, tendo como principal alternativa o uso da respiração para perder calor em situações de alta temperatura. Alternativas estruturais, como ventilação, gotejamento, resfriamento de piso e uso de processo evaporativo adiabáticos servem para amenizar as perdas produtivas. O objetivo do estudo foi analisar a influência de três sistemas de ambiência utilizando as variáveis temperatura e umidade relativa do ar, sobre os aspectos produtivos de fêmeas suínas e suas leitegadas. Foram utilizadas 244 fêmeas, em três tratamentos e três repetições. Ambiente climatizado - AC (n= 79), temperatura da sala de maternidade controlada por um sistema de resfriamento evaporativo adiabático, associado à ventilação negativa; Ar sobre as fêmeas - ASF (n= 82), saída individual de ar refrigerado sobre as fêmeas associado ao manejo de cortinas; Manejo de cortinas - MC (n= 83). Nas matrizes foi avaliado; o peso, a espessura de toucinho (ET), o escore corporal visual (ECV) pós-parto e ao desmame, e o intervalo desmame-estro (IDE) e o consumo médio diário de ração (CMR) na lactação. Dos leitões foi registrado o peso na uniformização, aos 14 dias e ao desmame. As mínimas e máximas diárias das variáveis temperatura e umidade relativa do ar (UR) foram mensuradas, bem como calculados as médias destas. As variáveis foram analisadas pelo procedimento GLM. As médias foram comparadas pelo teste de Tukey-Kramer, com nível de 5% de significância. A temperatura média observada no tratamento AC (23,0ºC) foi inferior e a UR (88,5%) superior quando comparada as dos demais. Para o CMR foi observada uma interação significativa entre os tratamentos e as repetições avaliadas. Na primeira repetição, o CMR foi maior no AC do que no MC. Na segunda repetição, não houve diferença entre os sistemas e, na terceira, os três sistemas diferiram entre si, com o maior CMR sendo observado no AC e o menor no MC. Apesar disso não foram observadas diferenças com relação a perda de peso lactacional e IDE. No entanto, o peso dos leitões ao desmame no AC (6164,2 g) foi semelhante aos demais, enquanto no ASF (6205,5 g) foi superior ao MC (5970,2 g). O tratamento ambiente climatizado foi efetivo em diminuir a temperatura ambiente, sendo uma alternativa para prover conforto térmico às fêmeas lactantes. No tratamento AC, o consumo de ração pelas fêmeas foi maior em uma das repetições, mas os leitões dos tratamentos AC e ASF tiveram desempenho semelhante e o primeiro não diferiu do MC, provavelmente por terem mobilizado mais energia para a manutenção da temperatura. / Maintaining sows outside the zone of thermal comfort compromises their performance, especially during lactation, mainly due to reductions in voluntary feed intake and milk production. The heat stress is a challenge because of the difficulty of the sow to dissipate heat with the main alternative use of breathing to lose heat in situations of high temperature. Structural alternatives, such as ventilation, drip, cooling and floor using adiabatic evaporative cooling to mitigate losses arising productive. This study analyzes the influence of three different cooling systems on the productivity of sows and their litters using the variables temperature and relative humidity. Two hundred and forty-four females were divided into three treatment and three replication groups: air-conditioned - AC (n = 79), with farrowing house temperature controlled by a system of adiabatic evaporative cooling combined with negative ventilation; snout cooler - SC (n = 82), with a cold air outlet directed towards females, combined with management of curtains; and management of curtains - MC (n = 83). The following variables were assessed for all sows: weight, backfat thickness (BFT), and visual body condition score (BCS), postpartum and at weaning, as well as weaning-to-estrus interval (WEI) and average daily feed intake (ADFI) during lactation. Piglet weight was recorded at cross-fostering, after 14 days, and at weaning. Minimum and maximum daily temperatures and relative humidity (RH) were measured and averaged. Variables were analyzed using the GLM procedure and means were compared using the Tukey-Kramer test at the 5% level of significance. Lower temperature averages were found for the AC treatment (23.0°C) and higher for RH (88.5%) than for others. There was significant interaction between treatment and evaluation periods for ADFI. In the first period, ADFI was higher in the AC group than in the MC one. In the second, there was no difference between the systems, while the three systems differed significantly in the third, with the largest ADFI found in AC and the lowest in MC. Yet there were no differences with respect to lactation weight loss and WEI. However, piglet weight at weaning in the AC group (6164.2g) was lower than in the SC (6205.5g) and higher than in the MC (5970.2g). The air-conditioned room treatment was effective in decreasing the temperature, and an alternative to provide thermal comfort to the lactating. In the air-conditioned room treatment, feed intake by females was higher in the replications, but the piglets from treatments air-conditioned room and snout cooler were similar and not different from the first management of curtains, probably because they had mobilized more energy to maintain temperature.

A manutenção das matrizes suínas fora da zona de conforto térmico compromete o seu desempenho, em especial no período lactacional, devido a redução no consumo voluntário de ração e na produção de leite. O estresse por calor é um desafio devido a dificuldade da espécie em dissipar calor, tendo como principal alternativa o uso da respiração para perder calor em situações de alta temperatura. Alternativas estruturais, como ventilação, gotejamento, resfriamento de piso e uso de processo evaporativo adiabáticos servem para amenizar as perdas produtivas. O objetivo do estudo foi analisar a influência de três sistemas de ambiência utilizando as variáveis temperatura e umidade relativa do ar, sobre os aspectos produtivos de fêmeas suínas e suas leitegadas. Foram utilizadas 244 fêmeas, em três tratamentos e três repetições. Ambiente climatizado - AC (n= 79), temperatura da sala de maternidade controlada por um sistema de resfriamento evaporativo adiabático, associado à ventilação negativa; Ar sobre as fêmeas - ASF (n= 82), saída individual de ar refrigerado sobre as fêmeas associado ao manejo de cortinas; Manejo de cortinas - MC (n= 83). Nas matrizes foi avaliado; o peso, a espessura de toucinho (ET), o escore corporal visual (ECV) pós-parto e ao desmame, e o intervalo desmame-estro (IDE) e o consumo médio diário de ração (CMR) na lactação. Dos leitões foi registrado o peso na uniformização, aos 14 dias e ao desmame. As mínimas e máximas diárias das variáveis temperatura e umidade relativa do ar (UR) foram mensuradas, bem como calculados as médias destas. As variáveis foram analisadas pelo procedimento GLM. As médias foram comparadas pelo teste de Tukey-Kramer, com nível de 5% de significância. A temperatura média observada no tratamento AC (23,0ºC) foi inferior e a UR (88,5%) superior quando comparada as dos demais. Para o CMR foi observada uma interação significativa entre os tratamentos e as repetições avaliadas. Na primeira repetição, o CMR foi maior no AC do que no MC. Na segunda repetição, não houve diferença entre os sistemas e, na terceira, os três sistemas diferiram entre si, com o maior CMR sendo observado no AC e o menor no MC. Apesar disso não foram observadas diferenças com relação a perda de peso lactacional e IDE. No entanto, o peso dos leitões ao desmame no AC (6164,2 g) foi semelhante aos demais, enquanto no ASF (6205,5 g) foi superior ao MC (5970,2 g). O tratamento ambiente climatizado foi efetivo em diminuir a temperatura ambiente, sendo uma alternativa para prover conforto térmico às fêmeas lactantes. No tratamento AC, o consumo de ração pelas fêmeas foi maior em uma das repetições, mas os leitões dos tratamentos AC e ASF tiveram desempenho semelhante e o primeiro não diferiu do MC, provavelmente por terem mobilizado mais energia para a manutenção da temperatura. / Maintaining sows outside the zone of thermal comfort compromises their performance, especially during lactation, mainly due to reductions in voluntary feed intake and milk production. The heat stress is a challenge because of the difficulty of the sow to dissipate heat with the main alternative use of breathing to lose heat in situations of high temperature. Structural alternatives, such as ventilation, drip, cooling and floor using adiabatic evaporative cooling to mitigate losses arising productive. This study analyzes the influence of three different cooling systems on the productivity of sows and their litters using the variables temperature and relative humidity. Two hundred and forty-four females were divided into three treatment and three replication groups: air-conditioned - AC (n = 79), with farrowing house temperature controlled by a system of adiabatic evaporative cooling combined with negative ventilation; snout cooler - SC (n = 82), with a cold air outlet directed towards females, combined with management of curtains; and management of curtains - MC (n = 83). The following variables were assessed for all sows: weight, backfat thickness (BFT), and visual body condition score (BCS), postpartum and at weaning, as well as weaning-to-estrus interval (WEI) and average daily feed intake (ADFI) during lactation. Piglet weight was recorded at cross-fostering, after 14 days, and at weaning. Minimum and maximum daily temperatures and relative humidity (RH) were measured and averaged. Variables were analyzed using the GLM procedure and means were compared using the Tukey-Kramer test at the 5% level of significance. Lower temperature averages were found for the AC treatment (23.0°C) and higher for RH (88.5%) than for others. There was significant interaction between treatment and evaluation periods for ADFI. In the first period, ADFI was higher in the AC group than in the MC one. In the second, there was no difference between the systems, while the three systems differed significantly in the third, with the largest ADFI found in AC and the lowest in MC. Yet there were no differences with respect to lactation weight loss and WEI. However, piglet weight at weaning in the AC group (6164.2g) was lower than in the SC (6205.5g) and higher than in the MC (5970.2g). The air-conditioned room treatment was effective in decreasing the temperature, and an alternative to provide thermal comfort to the lactating. In the air-conditioned room treatment, feed intake by females was higher in the replications, but the piglets from treatments air-conditioned room and snout cooler were similar and not different from the first management of curtains, probably because they had mobilized more energy to maintain temperature.

This work is concerned with the design, development and performance evaluation of an inertance Pulse Tube Cryocooler (PTC). The main components of a PTC are the compressor, regenerator, pulse tube and inertance tube coupled to a reservoir. The inertance tube is a key component that affects the pressure and mass flow and phase shift between them and hence the performance. In conjunction with the compressor, it also plays a strong role in determining the frequency of operation. The PTC is designed based on system level numerical models (SAGE and DeltaE), component level thermo-acoustic models (DeltaE) of inertance tube and regenerator and experimental data of earlier fabricated Stirling coolers. As a starting point, an inertance tube with a diameter of 3 mm and 3.1 m long was chosen through component level analysis that provides phase shift of around 50 degrees at a pressure ratio of 1.1 for an acoustic power of about 4 W (in order to achieve 1 W of net cooling at 80 K) at 25 bar mean pressure and 60 Hz. From this inertance tube geometry, an estimate of the mass flow rate at the cold heat exchanger is obtained. Based on this mass flow rate, the initial dimensions of the pulse tube and regenerator are arrived at. A parametric study using system level model is carried out to obtain the maximum COP by varying inertance tube length and regenerator diameter. A flexure bearing compressor consisting of moving coil linear motor coupled to a piston is designed for the above cold head. Based on the above design considerations, the PTC compressor and cold head are fabricated and assembled. The PTC is charged with helium at mean pressure of 25 bar and instrumented with pressure and position transducers, temperature sensors and a skin-bonded heater for simulating the heat load on the cold head. Experimental data for the PTC were obtained with two different inertance tube lengths for different frequencies of operation. The cold head temperature exhibited a minimum with respect to the frequency. This optimum frequency shifts towards lower frequency with increased length of the inertance tube. The experimental data clearly shows that with different inertance tube lengths the optimum frequency locates itself for obtaining zero phase shift at the middle of the regenerator. It is observed that the optimum frequency is closely linked to the natural frequency of the pressure wave in the inertance tube suggesting a standing wave within the inertance tube with the pressure node at the reservoir. Thus the inertance tube is found to be analogous to a quarter wave resonator in a thermo-acoustic device. It may thus be possible to pre-fix an operating frequency for a given PTC cold head by choosing an inertance tube length close to quarter wave resonator length. This study has given insights on the phase shift between pressure and mass flow rate governed by the inertance tube and the connection between the optimum and natural frequencies which can be used for better design of PTCs.

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Made available in DSpace on 2014-10-09T12:54:00Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:26Z (GMT). No. of bitstreams: 1 12431.pdf: 23287148 bytes, checksum: ca5f3b291fb81099ce731e9a131ce645 (MD5) / Tese (Doutoramento) / IPEN/T / Escola Politecnica, Universidade de Sao Paulo - POLI/USP