Thesis (MPA.) --University of Limpopo, 2016 / Refer to the document

Thesis: M.S., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1976 / Includes bibliographical references. / by Wee T. Yee. / M.S. / M.S. Massachusetts Institute of Technology, Department of Mechanical Engineering

Made available in DSpace on 2017-05-12T14:46:56Z (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.

Today's utilities face new challenges due to the continually increasing penetration of residential solar and other distributed, stochastic generation sources. In order to maintain balance and stability in the grid without building costly, large-scale generation plants, utilities are turning to distributed energy resources for use in demand response programs. Demand response is a cost-efficient way to balance grid load/generation without the need for increased capital investment in traditional generation resources. Demand response programs are excellent exploiters of end-user devices that otherwise further accentuate the daily load curve and thus, add to the difficulties created by daily load peaks. Electric water heaters are excellent candidates for use in demand response programs for a variety of reason. One, electric water heaters represent a large portion of daily household loads due to their high nominal power ratings (1.5 kW - 5.5kW), and frequent use estimated to account for approximately one third of all daily residential power demand. Two, they are composed of strictly resistive elements, which greatly simplifies modeling, aggregation and control. And third, they can be used for load "shedding" during periods of high electrical demand as well as load "absorbing" during periods of excess generation due to their thermal storage capabilities. With improved access and control, electric water heaters could become a major distributed energy resource for utilities. In order to properly control and use a distributed energy resource, it is important to know how these resources operate and their patterns of behavior in different environments. This thesis presents a single-element, single mass electric water heater model for analyzing the effectiveness of using electric water heaters as distributed energy resources and for participation in demand response programs. The CTA-2045 communication protocol was used for testing demand response signals. The electric water heater is modeled in Python and the communication pathway was built in C++ and Python.

Energy efficient technologies and renewable energy technologies are becoming less of a novelty in the American energy mix. These technologies offer the promise of a decreased dependence on foreign oil, considerable savings of energy bills, and protections for the environment. Despite the many potential benefits, these technologies face many barriers to adoption. The lack of renewable energy technologies and energy efficient technologies is particularly damaging in the State of Hawaii, where 90% of energy needs are met with imported fossil fuels. This report focuses on the current energy policies in Hawaii and the barriers to the incorporation of renewable energy technologies and energy efficient technologies, specifically solar water heaters. / text

Within the international context, energy has become a central factor in our everyday ways of life. There is increasing dependence on energy resources such as electricity to improve people quality of life. In developing countries, many people still do not have access to energy due to several challenges that have hindered infrastructural development and economic growth. At the same time, there is a growing interest in the protection of the environment and addressing issues of climate change. Green technologies such as solar water heaters are identified as technologies that meet the need of both its end-users and the environment through the provision of hot water. Access to 'hot water' is seen to be an important element resulting in an improved quality of life. In addition, several methods of heating water are explored to assess the attitudes and perceptions that people have towards solar water heaters. The dissertation involved in-depth interviews with residents from low income RDP houses in Kwandengezi Coffee Farm and government officials from eThekwini Municipality involved in the solar water heater programme for low income communities. The interviews revealed that renewable energy interventions such as the solar heater programme for low income communities contribute significantly to an improvement in people‘s quality of life. The availability of solar heaters allows people to enjoy hot water at a free cost, hence an improvement in the quality of life. The research further revealed that such renewable energy interventions can contribute to a reduction in negative environmental impacts, hence facilitating the acquisition of hot water with less dependence on electricity resources. / M.Dev.Studies University of KwaZulu-Natal, Durban 2013.

The oxidation of three different steels used in the construction of petroleum refineryheaters was investigated by using thermogravimetric analysis technique (TGA). C-5,P-11, and P-22 steel samples were tested in two different oxidizing environments / air and CO2+N2+H2O (that simulates the combustion products of natural gas) at two different temperatures / 450oC and 500oC. In air oxidation P-22 had the best oxidation resistance among the three steels at two temperatures. In CO2+N2+H2O environment,C-5 possessed better oxidation resistance than P-22 and P-11. Analyses of oxidation products by using optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were carried out to correlate TGA results to oxide composition and morphology. Lower oxidation rate of P-22 in air was explained with reference to the formation of Cr-O phase. Analytical rate equations showed that all the steels obeyed parabolic rate equation during oxidation and no transition was observed

Thermal, electrical, and mechanical characteristics of heated cantilevers were experimentally studied in various conditions. Experiments investigated thermal, mechanical, and coupled behaviors of the heated cantilevers under DC, AC, and transient electrical heating. Raman spectroscopy measured local temperature and qualitative intrinsic stress with high spatial resolution. Based on the thorough understanding from device characterization, cantilever type micro hotplates and small array of heated cantilevers with integrated piezoresistive sensors were fabricated and characterized. Well characterized cantilever sensors were applied to heat transfer study and microfludic research. Heated microcantilevers were suggested to study sub-continuum heat transfer from a micro heater to ambient gas environment in a wide range of pressure. Microcantilever sensors were employed to study the free microjets emanated from microfabricated nozzles. Piezoresistive cantilevers measured jet thrust, velocity, and break-up distance of the liquid microjets and heated cantilevers investigated heat transfer characteristics and phase change phenomena during the microjet impingement.

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Η παρούσα διπλωματική εργασία έχει ως θέμα τον ευφυή έλεγχο μιας μηχανής Stirling χαμηλής θερμοκρασιακής διαφοράς, με στόχο την πρακτική εφαρμογή σε οικιακούς καταναλωτές για την παραγωγή ηλεκτρικής ενέργειας. Έγινε διασύνδεση μιας σειρά αισθητήρων (μέτρηση θερμοκρασίας) και επενεργητών (αντλίες) σε ένα πρωτότυπο σύστημα, έτσι ώστε να προσομοιωθεί κατά το καλύτερο δυνατό τρόπο η λειτουργία της αύξησης της θερμοκρασίας του υγρού σε ένα ηλιακό θερμοσίφωνα και της τυπικής οικιακής ημερήσιας κατανάλωσης. Με βάση αυτό το πρότυπο παραγωγής και κατανάλωσης ενέργειας διαμορφώθηκε ένας ευριστικός έλεγχος έτσι ώστε να παραχθεί η περισσότερη ηλεκτρική ενέργεια χωρίς να παραβιασθούν μία σειρά από περιορισμούς που αφορούν στην χρήση του ηλιακού θερμοσίφωνα. Πειραματικά αποτελέσματα επιβεβαιώνουν την αποτελεσματικότητα της μηχανής Stirling και την ανάγκη προσαρμοστικοτητας της λειτουργίας της έτσι ώστε να ανταποκρίνεται στις ιδιάζουσες ανάγκες της κάθε οικογένειας. / This thesis is on the intelligent control of a Stirling engine with a low temperature difference in order to practice residential consumers for electricity production. An interface of a series of sensors (temperature measurement) and actuators (pumps) became in a prototype system in order to simulate as best as possible the function of warming the liquid in a solar water heater and the standard daily household consumption. Under this model of production and consumption was a Heuristic control order to generate more electricity without having violated a number of restrictions on the use of solar water heater. Experimental results confirm the effectiveness of the Stirling engine and the need for adaptability of its operation to meet the specific needs of each family.