Análise de termossifões que operam com mercúrio em altas temperaturas

AUTOR(ES)

André Felippe Vieira da Cunha

DATA DE PUBLICAÇÃO

2008

RESUMO

Thermosyphons are high thermal conductivity devices that can transfer high quantities of heat when subjected to small temperature gradients. In its most simple form, a thermosyphon is a hollow evacuated metal pipe, charged by a pre-determined amount of an appropriate working fluid. It can be divided into three main sections: evaporator, where the heat is delivered to the device, an adiabatic section (which may or may not exist) and a condenser, where the heat is released. First, an extensive literature review about thermosyphons and heat pipes for higher temperature levels (above 350o C) is presented. Information about heat pipes are useful for understanding the mechanical aspects involved in thermosyphons. The working fluid candidates are examined and some mathematical models are investigated. Literature correlations for several heat transfer coefficients observed during the operation of thermosyphons are also presented. A mathematical model is developed to predict the thermal behavior of liquid metal thermosyphon. The condensation and evaporation process are modeled based on the Nusselt model for flat plates. The temperature distribution along the tube and the thickness of the working fluid films are also modeled. Numerical methods are employed to solve the mathematical model developed. To generate data to be compared with the theoretical results, an experimental study was conducted, including the construction of an apparatus, which allows mercury thermosyphon tests in high temperature levels. The theoretical results of the model showed good agreement with experimental data in the condenser, but the comparison is less accurate in evaporator, consequence of the heat transfer coefficients of the pool and considerations adopted this model.

ASSUNTO(S)

metais líquidos - propriedades térmicas mercúrio engenharia mecanica tubos de calor calor - transmissão

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