Tranferencia de calor no escoamento de gases participantes em alta temperatura atraves de dutos de secção circular revestidos com isolamento não ideal

AUTOR(ES)

Francis Henrique Ramos França

DATA DE PUBLICAÇÃO

1995

RESUMO

In this Master degree thesis, the heat transfer in the flow of participating gases through circular cross section ducts is studied, combining the three basic processes: conduction, convection and radiation. It is considered the case in which a high temperature gas tlows through a tube covered by a non-ideal insulation. The gas inlet temperature is uniform and the thermal entry region is taken into consideration. The velocity profile is fully developed throughout the duct for both laminar and turbulent flows. The gas is composed by CO IND. 2 , H IND. 2 O e N IND. 2 and its physical properties are assumed to be constant and calculated at the average bulk temperature. The gas radiant properties are temperature dependent and evaluated through the weighted sum of gray gases model. The temperature field is obtained by the solution of the bidimensional energy conservation equation: the convective and difusive terms are discretized by the Flux-Spline control volume method; the radiative exchanges are determined by the zoning method, where each radiative zone corresponds to a control volume. The tube and insulation temperature distributions are obtained by the energy balance in the duct, which is coupled to the gas energy equation. The proposed calculation procedure and the computational code which was developed were verified by comparing the obtained results with those available in the literature regarding uniform duct temperature, when thermal radiation is considered or not. The results presented include the gas, tube and insulation temperature distributions, and the total, convective and radiative Nusselt number inside the duct. The effect of thermal radiation in the heat transfer was analysed as a function of the following parameters: gas inlet temperature, tube and insulation surface emittance, tube inner diameter, duct length and insulation thickness

ASSUNTO(S)

calor - convecção isolamento (calor) radiação calculos numericos calor - condução gas - escoamento tribulação - hidrodinamica

Documentos Relacionados

• Determinação do coeficiente de tranferencia de calor liquido-particula em escoamento atraves de tubulações e em banho agitado
• Transformada integral generalizada no escoamento laminar e transferência de calor em dutos retilíneos de geometria arbitrária
• Técnica de transformada integral generalizada no desenvolvimento simultâneo dos perfis de velocidade e temperatura em escoamento laminar em dutos de geometria simples
• Transferencia de calor de corpos imersos em leito fluidizado borbulhante em alta temperatura
• Coeficientes locais de tranferencia de calor em leito fluidizado rapido