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Doctoral Thesis
DOI
https://doi.org/10.11606/T.18.1997.tde-18072024-161825
Document
Author
Full name
Waldemir Silva de Lima
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1997
Supervisor
Committee
Celere, Samuel Washington (President)
Araujo, Jairo Augusto Campos de
Milioli, Fernando Eduardo
Santos, Joao Maria dos
Silva, Fabio Moreira da
Title in Portuguese
Estudo do fluxo convectivo de ar induzido por placas aquecidas no interior de canais verticais
Keywords in Portuguese
convecção natural
escoamento em canais
indução de fluxo
Abstract in Portuguese
O presente trabalho estuda o fluxo de ar induzido por uma placa tipo "sandwich" aquecida no interior de um canal vertical com paredes paralelas. O modelo constitui-se de um canal de seção transversal retangular com paredes duplas de compensado naval separadas por uma camada de poliestireno expandido montado na parte superior de uma câmara de estabilização, de modo que a placa aquecida, suspensa pelos termopares e cabos de alimentação nela embutidos, deslizasse em seu interior ocupando um total de nove posições. O fluxo de ar induzido foi medido por anemômetros de fio quente desenvolvidos especificamente para esse fim. A placa foi considerada isotérmica e o canal, de paredes adiabáticas. A partir da potência elétrica fornecida à placa, das temperaturas e vazões de ar envolvidas e da posição da placa no canal, obtiveram-se correlações para o número de Nusselt médio global em função do número de Rayleigh médio global modificado e do número de Reynolds médio global com erro máximo de 6,88% para o caso da placa polida e da pintada de preto. Os resultados mostraram que a placa pintada de preto é em média 24,435% mais eficiente como indutora de fluxo de ar, e a melhor posição para uso da placa como sistema de exaustão ambiental é localizando-a na parte central superior do canal
Title in English
.
Keywords in English
induced flux
natural convection
outflow in channels
Abstract in English
The present work study the induc.ed air flux for a sandwiched heated plate within a vertical wall channel. The constituted studied model was a channel with a rectangular cross section and, double naval veneer wall, spaced for a thin layer of expanded polystyrene mounted at the upper part of a stabilisation chamber giving possibility by this way, that the heated plate, li:fted for your owns embedded thermocouples and electrical feedings wires, could slip in the inner part of the channel, standing in a total of nine positions. The induced air flux was measured by a hot wire anemometer specially designed to this. The plate was considered isothermal and the channel, with adiabatic walls. With the delivered electric power to the plate, temperatures, flow mass of air and plate's position, was determined mathematical correlation to determine the over-all mean Nusselt number like a function ofthe over- all mean modified Rayleigh number and ofthe over-all mean Reynolds number, with a 6,88% fraction of maximum error to the polished and black painted plate' s cases. The results showed that the black painted plate have an effectiveness 24,435% higher than the polished plate to induce flux of air and, that the better position to use the plate like environmental exhaustion system is locating it in the upper central part of the channel.
 
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Lima_Waldemir_DO.pdf (8.40 Mbytes)
Publishing Date
2024-07-18
 
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