Thesis (M.S.)--University of Wisconsin--Madison, 1922. / Typescript. Bulletin, University of Washington Engineering Experiment Station. Engineering Experiment Station series, Bulleting No. 15, December, 1921. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xvii, 153 p.; also includes graphics (some col.) Includes bibliographical references (p. 145-153). Available online via OhioLINK's ETD Center

published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering

Thesis--M. Sc.(Eng.), University of Hong Kong. / Offset from typescript.

Since the nineteen-seventies, electricity has become a common heating source in Swedish single-family houses. About one million smallhouses can use electricity for heating, about 600.000 have electricity as the only heating source. A liberalised European electricity market would most likely raise the Swedish electricity prices during daytime on weekdays and lower it at other times. In the long run, electrical heating of houses would be replaced by fuels, but in the shorter perspective, other strategies may be considered. This report evaluates the use of electricity for heating a dwelling, or part of it, at night when both the demand and the price are low. The stored heat is utilised in the daytime some hours later, when the electricity price is high. Essential for heat storage is the thermal time constant. The report gives a simple theoretical framework for the calculation of the time constant for a single-family house with furniture. Furthermore the “comfort” time constant, that is, the time for a house to cool down from a maximum to a minimum acceptable temperature, is derived. Two theoretical model houses are calculated, and the results are compared to data from empirical studies in three inhabited test houses. The results show that it was possible to store about 8 kWh/K in a house from the seventies and about 5 kWh/K in a house from the eighties. The time constants were 34 h and 53 h, respectively. During winter conditions with 0°C outdoor, the “comfort” time constants with maximum and minimum indoor temperatures of 23 and 20°C were 6 h and 10 h. The results indicate that the maximum load-shifting potential of an average single family house is about 1 kW during 16 daytime hours shifted into 2 kW during 8 night hours. Up-scaled to the one million Swedish single-family houses that can use electricity as a heating source, the maximum potential is 1000 MW daytime time-shifted into 2000 MW at night.

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Includes bibliographical references. / M.S.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016. / The performance of a wall Mounted space comfort heater has been studied with respect to the geometry of its mounting condition. Tests were conducted in a laboratory with the heater positioned at various heights from the floor and the channel that is created by the various gaps with the wall on which the heater was mounted. Tests were also performed with the heater mounted on the wall whose emissivity was adjusted to low, medium and high values as well as placing insulation material on the wall directly behind the heater. The outcome of the experiments revealed an acceptable geometry of the heater’s mounting at least 200 mm above the floor, and 50 mm off-set from the wall. The results of the heater mounted against the wall revealed a drop in performance as compared to the heater’s “benchmark” performance when it was freely standing on the floor of the laboratory; with an efficiency of about 41% (almost evenly shared by each face). This efficiency, which is based on the convective heat transfer generated by the heater’s warm/hot surfaces, is relative to the electrical energy input and it dropped when the heater was mounted against a grey wall to around 35%, of which only 26% was produced inside the channel. The heat transfer by radiation from the heater’s surface is treated as net loss to the walls of the room/enclosure.The performance of the heater when mounted against the wall improved almost to the benchmark value when the wall behind the heater was made refelective (low emissivity). It is recommended that further research should be undertaken to thoroughly investigate the “mode” of heat transfer, by the induced flow through the channel, in a more formal or scientific modelling approach.

Made available in DSpace on 2014-10-09T12:28:08Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:44Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:28:08Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:44Z (GMT). No. of bitstreams: 0 / Em um reator nuclear PWR a temperatura do refrigerante do circuito primário e a da água de realimentação são medidas usando RTD (Resistance Temperature Detectors), ou termômetros de resistência. Estes RTDs alimentam os sistemas de controle e segurança da usina e devem, portanto, ser muito precisos e ter bom desempenho dinâmico. O tempo de resposta dos RTDs é caracterizado por um parâmetro denominado de Constante de Tempo, definido como sendo o tempo que o sensor leva para atingir 63,2% do seu valor final após sofrer uma variação de temperatura em forma de degrau. Este valor é determinado em laboratório, porém as condições de operação de reatores nucleares são difíceis de ser reproduzidas. O método LCSR (Loop Current Step Response), ou teste de resposta a um degrau de corrente, foi desenvolvido para medir remotamente o tempo de resposta dos RTDs. A partir desse teste, a constante de tempo do sensor é calculada através de uma transformação LCSR que envolve a determinação das constantes modais do modelo de transferência de calor. Este cálculo não é simples e requer pessoal especializado. Por este motivo, utilizou-se a metodologia de Redes Neurais Artificiais para estimar a constante de tempo do RTD a partir do LCSR. Os testes LCSR foram usados como dados de entrada da RNA; os testes de Imersão Rápida foram usados para determinar a constante de tempo dos sensores, sendo estes os valores desejados de saída da rede. Esta metodologia foi aplicada inicialmente a dados teóricos, simulando dez sensores com diferentes valores de constante de tempo, resultando em um erro médio de aproximadamente 0,74 %. Dados experimentais de 3 diferentes RTDs foram usados para estimar a constante de tempo, resultando em um erro máximo de 3,34 %. Os valores de constante de tempo estimados pelas RNAs foram comparados com aqueles obtidos pelo método tradicional, obtendo-se um erro médio de 18 % o que mostra que as RNAs são capazes de estimar a constante de tempo de uma forma precisa. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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