Transparent conducting oxides (TCOs) have become an integral part of modern life through their essential role in touchscreen technology. The growing demand for cheap and superior transparent conducting layers, primarily driven by the smart phone market, has led to renewed efforts to develop novel TCOs. Currently, the most widely used material for transparent conducting applications is Sn-doped indium oxide (ITO), which has outstanding optical and electrical properties. This material is expensive though, due to the extensive use of In, and efforts to develop new low-cost transparent conducting oxides (TCO) have become increasingly important. Similarly attempts to reduce the cost of the fabrication and post-sintering steps used in making doped metal oxide thin films through innovative technologies have gained a lot of attention. With these points in mind, this research project has focused on the development of a novel low-cost aerosol assisted physical deposition method for TCO thin film fabrication and the development of new highly conducting materials to replace the expensive ITO for TCO applications. In this study, a new and simple aerosol assisted vapour deposition technique (i.e AACT) is developed to fabricate TCO films using TCO nanoparticle suspensions. Firstly, to test the validity of the method, ITO thin films are fabricated on float glass substrates from a nanoparticle suspension. The influence of the deposition parameters on the structural and opto-electronic properties of the thin films are investigated to understand the intricacies of the process. In order to investigate the fabrication of replacement materials for ITO, a range of doped zinc oxide powders are synthesised and processed using microwave radiation. Nominally, Al doped ZnO (AZO), Ga doped ZnO (GZO), Si doped ZnO (SZO), Cu doped ZnO (CZO) and Mn doped ZnO (MZO) singly doped ZnO powders are all investigated to determine the best metal dopants for transparent conducting ZnO. AZO and GZO pellets are found to present the best electrical conductivity for the singly doped microwave fabricated powders with values of 4.4 x 10-3 and 4.3 x 10-3 Ω.cm achieved reproducibly. In an effort to further improve the properties of ZnO, co-doping experiments, utilising the two best dopants from the previous work (i.e. Al and Ga) is investigated. ZnO structures that are co-doped with Al and Ga (AGZO) are found to exhibit significantly enhanced electrical properties than the singly doped powders. Typically, electrical conductivity value of 5.6 x 10-4 Ω.cm is obtained for AGZO pellets, which is an order of magnitude better than the previously fabricated materials. Finally, the best AZO, GZO and AGZO materials are utilised to fabricate thin films using the previously verified AACT technique. Further investigations into the opto-electrical properties of the resulting thin films is presented prior to the utilisation of the best films in a practical application. Transparent heaters are fabricated using the best AGZO thin films, which are capable of reaching a mean temperature of 132.3 °C after applying a voltage of 18 V for 10 min. This work highlights the potential for using highly conducting AGZO, particularly fabricated by the microwave synthesis route, as a potential alternative for ITO in a wide variety of applications. The research also highlights the advantages of using microwaves in the thermal processing of TCO materials which significantly reduces the energy impact of the production process.

Orientador: João Francisco Escobedo / Banca: Dinival Martins / Banca: Alexandre Dal Pai / Banca: Erico Tadao Teramoto / Banca: Ricardo Molto Pereira / Resumo: O principal objetivo deste estudo é avaliar, com bases em resultados experimentais, um sistema de aquecimento solar constituído de mangueira de polietileno que permite a transferência do calor gerado pela radiação solar direta e/ou difusa (Energia Solar Térmica) para a água. O sistema foi dimensionado para atender a demanda de um Centro de Ressocialização com capacidade para 220 internos. Justifica-se a escolha do tema pelo fato de que consiste em um assunto atual de grande relevância, principalmente porque vive-se uma crise energética em nível mundial. O estudo comprova através de um experimento a viabilidade do aquecedor solar de baixo custo, considerando-se sua aplicabilidade em locais que demanda grande volume de água aquecida para banho. Os resultados demonstraram que o sistema alternativo proposto atendeu de forma eficiente e econômica a demanda solicitada, o que pode ser adotada pelo poder público em qualquer um de seus segmentos que necessite de água aquecida, com objetivo de reduzir custos e contribuir com o sistema energético brasileiro. O sistema foi analisado para atuar em fluxo continuo e fluxo intermitente, ambos objetivando aquecer a água a temperaturas superiores a 37 °C no inverno. Os resultados alcançados atenderam as expectativas coletando grandes volumes, com temperaturas médias acima de 42 °C. / Abstract: The aim of this study is to evaluate, with bases on experimental results, a solar heating system consists of polyethylene hose that allows the transfer of heat generated by direct solar radiation and / or diffuse (Solar Thermal Energy) to the water. The system has been designed to meet the demand of a Rehabilitation Center with a capacity for 220 inmates. Justified the choice of the theme for the fact that consists of a current subject of great importance, especially because it lives in an energy crisis worldwide. The study proves through an experiment the viability of solar heater low cost, considering their applicability in places that demand large volume of heated water for bathing. The results showed that the alternative system proposed met efficiently and economically the requested demand, which can be adopted by the government in any of its segments that need heated water, in order to reduce costs and contribute to the Brazilian energy system. The system was analyzed to operate in continuous flow, intermittent flow, both aiming at heating the water to temperatures above 37 °C in winter. The results achieved met the expectations collecting large volumes, with average temperatures above 42 °C. / Doutor

Made available in DSpace on 2017-07-10T19:23:43Z (GMT). No. of bitstreams: 1 Fernanda Catelan.pdf: 917807 bytes, checksum: 1eb69893664d6f85f570a2e83ee5cc80 (MD5) Previous issue date: 2007-02-16 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The general aim of this research was to study the effects of different heating systems on the bioeconomic development of broilers from day 1 to day 45. The experiment was carried out during the winter of 2005, in commercial broiler houses located in western Paraná. The research was developed in a 1200 m2 broiler houses, with male broilers, from three different breedings, in the period between birth and slaughter on day 45, for each analyzed treatment. The adopted treatments for the economic evaluation of the different heating systems were automatic wood-burning system and automatic infrared gas system. The economic evaluation was made analyzing the energy consumption by the heaters in each treatment the gas the wood-burning through the bioeconomic index and the gross margin. The zootechnical indexes, which were evaluated, were the average weight gain and the feed consumption. The statistical data evaluation was by a randomized block in a factorial 2 X 3 model, two heating systems (automatic wood-burning and automatic infrared gas systems), three breedings broilers (A, B, C), made up by six treatments and six repetitions, totaling thirty-six broiler houses with thirteen thousand three hundred (13.300) birds each. The averages were analyzed by the Tukey test. For the general analyses of the results the Software Statistic® was utilized. The results showed that, in relation to energy consumption, the wood-burning system presented a higher energy consumption due to the lower heating power of wood, compared to the infrared gas system. Although the gas system has exhibited a higher production cost, it is still being used by the business owners. There was not a significant difference for the gross margin values and the bioeconomic index worked out for the different treatments. / O objetivo geral desta pesquisa foi o de estudar o efeito de diferentes sistemas de aquecimento sobre o desempenho bioeconômico de frangos de corte de um a 45 dias. O experimento foi realizado no período de inverno de 2005, em propriedades de produção industrial de frangos de corte, localizada no oeste do estado do Paraná. A pesquisa foi desenvolvida em aviários de 1200 m2, com frangos machos, de três linhagens diferentes, entre o nascimento e abate aos 45 dias, para cada tratamento estudado. Os tratamentos adotados para a avaliação econômica dos diferentes sistemas de aquecimento foram: sistema de aquecimento automático infravermelho a gás e sistema de aquecimento automático a lenha. A avaliação econômica foi realizada por meio de consumo de energia pelos aquecedores, a lenha e a gás, através da margem bruta e índice bioeconômico. Os índices zootécnicos avaliados foram: ganho médio de peso e consumo de ração. A avaliação estatística dos dados foi realizada, considerando o delineamento em blocos ao acaso em um modelo fatorial 2 x 3, dois sistemas de aquecimento (sistema de aquecimento automático infravermelho a gás e sistema de aquecimento automático a lenha), três linhagens de pintos machos (A, B e C), composto por seis tratamentos e seis repetições, perfazendo um total de 36 aviários com treze mil e trezentas (13.300) aves cada um. As médias foram analisadas através do teste de Tukey. Para a análise geral dos resultados, foi utilizado o Software Statistic®. Os resultados mostram que, em relação ao consumo energético, o sistema de aquecimento a lenha teve o maior consumo de energia, isso ocorre devido ao menor poder calorífico da lenha, em relação ao GLP. Porém, o sistema a gás apresentou maior custo de produção, mas continua sendo utilizado pelos avicultores. Não houve diferença significativa para os valores de margem bruta e para o índice-bioeconômico calculados para os diferentes tratamentos.

Manufacturers of feedwater heaters (FWHs) are obliged to disclose a specification sheet to the client that describes their FWH design. However, the client is unable to verify the performance of this FWH design without comparing it to the results that are predicted by a thermal model. An additional limitation is that the manufacturer will only disclose the minimum number of design parameters. The purpose of this study was to develop a thermal model that can predict the performance of a FWH. The model requires the minimum design input data to predict the performance parameters that may be compared to values predicted by the vendor. A FWH in a regenerative water-steam Rankine cycle achieves heat transfer to the feedwater by condensing steam on the shell side. This is called a single zone FWH. The tube plate type FWH is the most common type of FWH referenced in literature but the following variations may exist: • The Eskom fleet consist of both tube plate and header type FWHs. • FWHs may be orientated vertically or horizontally. Internal shrouded regions, that define it as a 2 or 3 zone FWH, may be present in the FWH. The length of the drains cooler (DC) zone may either be identified as long or short. A general model was required to capture all these design variations. Plant visits were arranged with engineers at several power stations to obtain the minimum input data and to confirm that these FWH design variations existed within the Eskom fleet. The model was based on existing tube plate models found in literature. It was then extended to accommodate the FWH variations mentioned above. A further improvement was made by including an additional heat transfer sub-zone that removes excess superheat in the condensing (COND) zone. The vendor does not disclose the correlations used to predict the film heat transfer coefficients (h) in their design. Therefore, the user is granted the option of selecting a correlation from a list of popular correlations, specific to a heat transfer mode. Note that the uncertainty associated with this thermal model is affected by the uncertainty of each correlation selected in the model.

No description available.

Residential water heating is linked to the primary source of waterborne disease outbreaks in the United States, and accounts for greater energy demand than the combined water/wastewater utility sector. To date, there has been little research that can guide decision-making with regards to water heater selection and operation to minimize energy costs and the likelihood of waterborne disease. We have outlined three types of systems that currently dominate the marketplace: 1) a standard hot water tank with no hot water recirculation (STAND), 2) a hot water tank with hot water recirculation (RECIRC), and 3) an on-demand tankless hot water system with no hot water recirculation (DEMAND). Not only did the standard system outperform the hot water recirculation system with respect to temperature profile during flushing, but STAND also operated with 32 – 36% more energy efficiency. Although RECIRC did in fact save some water at the tap, when factoring in the energy efficiency reductions and associated water demand, RECIRC actually consumed up to 7 gpd more and cost consumers more money. DEMAND operated with virtually 100% energy efficiency, but cannot be used in many circumstances dependent on scaling and incoming water temperature, and may require expensive upgrades to home electrical systems. RECIRC had greater volumes at risk for pathogen growth when set at the lower end of accepted temperature ranges, and lower volumes at risk when set at the higher end when compared to STAND. RECIRC also tended to have much lower levels of disinfectant residual (40 -850%), 4-6 times as much hydrogen, and 3-20 times more sediment compared to standard tanks without recirculation. DEMAND had very small volumes of water at risk and relatively high levels of disinfection. A comparison study of optimized RECIRC conditions was compared to the baseline modes of operation. Optimization increased energy efficiency 5.5 – 60%, could save consumers 5 – 140% and increased the disinfectant residual up to 560% higher disinfectant residual as compared to the baseline RECIRC system. STAND systems were still between 3 – 55% more energy efficient and could save consumers between $19 - $158 annual on water and electrical costs. Thus, in the context of “green” design, RECIRC systems provide a convenience to consumers in the form of nearly instant hot water, at a cost of higher capital, operating and overall energy costs. / Ph. D.

The nighttime losses from an integral collector storage (ICS) system were investigated. The significance of the sky temperature, wind speed, and ambient temperature on the losses were examined. Outdoor data was taken on several nights to characterize the thermal performance of an ICS system under various environmental conditions. Indoor tests were then performed under an artificial "nighttime sky" environment, with a simulated wind, in an attempt to duplicate the heat losses which occurred outdoors. The standard rating procedure which specifies the conditions for the heat loss tests for ICS systems was analyzed to see how well it characterizes the collector performance at night. Experimental results indicate a synergistic effect between the sky temperature and wind speed. The effects of wind on the losses from the ICS system overshadow the effects of small changes in sky temperature, but larger changes of sky temperature, with a constant wind speed, have a pronounced effect. It is recommended that both of these parameters be taken into account in heat loss tests in standard rating procedures. Indoor tests can duplicate outdoor heat loss results within 8 per cent. The minimum requirement for SRCC rating tests should be to monitor, record, and report the sky temperature. / M.S.

All-day experimental tests were performed to determine the thermal performance of two commercial integral storage collectors for solar domestic hot water systems. These tests were performed under a variety of ambient conditions and irradiance levels, both with and without forced circulation and noontime hot water draws. An analytical model was developed to predict the thermal performance of one of the two systems tested and predicted performance was compared with experimental results. Experimental and analytical results indicate that thermal stratification has a mininal effect on the daily collection efficiency of integral storage collector, so that a standard test similar to ASHRAE Standard 93-77 might reasonably be used to obtain the performance characteristics of the collection element of these systems. The results of an ASHRAE 93-77 type test might then be used to obtain performance ratings under ASHRAE Standard 95 procedures using an in-line heat source. The results of the present investigation may be used to validate such an ASHRAE 95 test method. / Master of Science

This study presents a comparison of field measurements of energy delivered by five integral collector storage (ICS) passive solar water heater systems installed at various geographic locations in Virginia to predicted values calculated using Annual Performance Methodology (APM). APM is a prediction method developed by Alan Zollner that offers quick and easy comparisons of design option for ICS systems. Several different methods exist today that are meant to predict the performance of this type of system and that might be used as a design tool to help a designer make appropriate design decisions. Some of these methods are quite complicated and do not lend themselves to quick and easy comparisons of various design options. This study measured the amount of energy delivered by five ICS systems over a six month period. The amount of water drawn out of these systems daily was also recorded. This data was compared to predicted values calculated using APM to determine if APM could predict the performance of these systems within plus or minus 15 percent of the measured values. This study demonstrates that APM was able to predict long term performance of ICS systems within plus or minus 15 percent eighty percent of the time. Short term performance however demonstrated variation that in some cases were quite large and could not be considered reliable predictions. / M. Arch.

Electric vehicles aim to carry the torch into a sustainable future. An optimized cooling system is crucial to an Electric Drive Unit (EDU). A smartly designed cooling system will deliver high-performance, efficient and long-lasting EDUs at lower costs. One way to achieve that is to have an integrated cooling system. When the electric motor and transmission share a common oil, the oil returning from the transmission side is aerated due to spraying and splashing. This aeration affects the pump performance and may reduce the cooling performance of the oil. Thus, this thesis is initiated to understand the impact of aeration on heat transfer.     Oil aeration is the presence of air in oil. This aeration depends on the air content and bubble sizes mixed in the oil. Typically, there is also some amount of dissolved air in any oil. Depending on the type of aeration, the oil will appear lighter than its usual colour and have a very foamy texture, showing a change in the properties of the fluid, for example density, viscosity and heat transfer.    An experimental setup is built in order to replicate and study the effect of aeration on local heat transfer. A flat channel with rectangular cross-section is designed with three parts – a bottom plate, a flow spacer channel and a top transparent plate. The oil and air are mixed before they enter the channel and then heated using thin film heaters. A groove within the bottom plate houses an insulating material, the thin film heater, a thermocouple touching the heater and a thermochromic liquid crystal sheet facing the fluid mixture. The thermocouple gives temperature readings from a single point between the heater and the insulating material. Meanwhile, the liquid crystal sheets come in different desired temperature ranges and change in colour from red to blue to show the surface temperatures over an area. So, the surface temperature of the mixed fluid flow can be recorded visually over an area with the thin film heater under it to calculate the heat transfer coefficients accordingly.    The drop in Nusselt number and heat transfer rates with increased aeration in the working fluid is the main highlight and result. The size of the air bubbles in the channel also determine how fast the heat transfer rate drops.