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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Estudo termo-hidraulico em tubos com intensificadores de troca de calor / Study hidraulical-thermal in pipes with intensifiers of heat exchange

Mendes, Valdirson Pereira 02 May 2004 (has links)
Orientador: Kamal Abdel Radi Ismail / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-13T06:37:12Z (GMT). No. of bitstreams: 1 Mendes_ValdirsonPereira_M.pdf: 606290 bytes, checksum: 25b8fe6db230e078d4fe26ed1ffe94b4 (MD5) Previous issue date: 2004 / Resumo: A intensificação da troca de calor avaliada fundamentalmente em termos do coeficiente de transferência de calor do escoamento em tubos lisos e com inserção de molas espirais de perfil circular e retangular foi investigado no presente trabalho. Nesse sentido, utilizou-se uma bancada experimental montada para tal avaliação. Os ensaios foram realizados fixando a temperatura de entrada na seção de ensaios na ordem de 2,6°C. Para a realização dos ensaios, a vazão mássica de água variou na faixa entre 0,050 a 0,310 kg/s, correspondendo a valores de Reynolds, Re, da ordem de 2900 e 15000, respectivamente. Os resultados experimentais mostram que o tubo com mola espiral com perfil retangular apresentou o melhor desempenho do coeficiente de transferência de calor, seguido do tubo com mola com perfil circular e do tubo liso. Para reduzidos valores de número de Reynolds, o coeficiente de transferência de calor para os três tubos tendem a mesma ordem. Os resultados experimentais mostram que a perda de carga aumentou com o incremento da vazão mássica, onde o tubo com mola com perfil retangular apresentou os maiores valores. Na análise final ao se avaliar o desempenho termo-hidráulico conclui-se que o tubo com mola espiral com perfil circular é um pouco superior do que o tubo com mola de perfil retangular. Analizou-se também os resultados obtidos por intermédio das correlações, de Gnielinski e de Bergles, comparando-as com os resultados obtidos experimentalmente. / Abstract: This study of change of heat appraised fundamentally in terms of coefficient of transfer of heat of the water in drainage in smooth tubes and with insert of spiral springs of circular and rectangular profile it was investigated in the present work. In that sense it was used a supported experimental mounted for such evaluation. The rehearsals were accomplished fixing the entrance temperature in the section of rehearsals in the order of 2,6°C. In the accomplishment of the rehearsals the mass flow of water varied in the interval among 0,50 to 0,310 kg/s corresponding to values of number Reynolds, Re, of the order from 2900 to 15000, respectively. The experimental results show that the tube with spiral spring with rectangular profile presented the best acting of the coefficient of transfer of heat, followed by the tube with spring with circular profile and of the smooth tube. For reduced values of number Reynolds the coefficient of transfer of heat for the three tubes was of the some order. The experimental results show that the load loss increased with the increment of the mass flow where the tube with spring with rectangular profile presented the largest values. In the analysis final to evaluate the term-hydraulic acting is ended that the tube with spiral spring with circular profile is a little larger than the tube with spring of rectangular profile. It was verified the results also obtained through the correlations, of Gnielinski and of Bergles comparing them with the results obtained experimentally. / Mestrado / Refrigeração e Condicionamento Ambiental / Mestre Profissional em Engenharia Mecanica

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