Luís Mauro Moura - lmoura@ccet.pucpr.br
Pontifícia Universidade Católica do Paraná
Centro de Ciências Exatas e de Tecnologia
Rua Imaculada Conceição, 1155 - Prado Velho, Cx. P. 16210
CEP 80215-901, Curitiba - PR - Brasil

This paper is focused on identification analysis for thermal radiation properties of dispersed media with a highly forward and backward peaked scattering. The direct model is based on a differential discrete ordinates method for an one-dimensional plane slab with azimuthal symmetry. An inverse method based on the Gauss linearization method is used to determine each of the unknowns. An identification used two different thickness samples is proposed means an uncertainties reduction on the identification.

Keywords: Thermal Radiation, Parameter Identification, Discrete Ordinates Method, Radiative Properties.
 
 

Sergio Mourão Saboya - saboya@mec.ita.cta.br
Instituto Tecnológico de Aeronáutica - ITA -IEME
12228-900 S. J. dos Campos - SP - Brasil

Francisco Eduardo Mourão Saboya - fsaboya@mec.uff.br
Universidade Federal Fluminense - UFF
Niterói - RJ - Brasil

Finned absorber solar collectors are devices in which plates (fins) are fixed perpendicularly to the absorber plate. The purpose of these fins is to cause the so called "cavity effect", lowering the collector losses. This paper studies the heat transfer that occurs in the collector channel. This analysis is done using the efficiency of the collector, which is calculated solving the system of equations that govern the collector thermal behavior, and the computation of the convection heat transfer between the fluid flowing in the channel and the absorber plate. This analysis allows the calculation of design parameters such as mass flow rate and exit bulk temperature of the fluid.

Keywords: Thermal Radiation, Solar energy, Solar collectors.
 
 

Rosana da Paz F. Pinheiro - rpaz@iprj.uerj.br
Antônio J. Silva Neto * - ajsneto@iprj.uerj.br
Instituto Politécnico, Universidade do Estado do Rio de Janeiro, CP 97.282, CEP 28601-970,
Nova Friburgo, RJ, Brasil.

In this work is solved an inverse radiative transfer problem for the simultaneous estimation of the absorption and scattering coefficients of one-dimensional homogeneous semitransparent participating media, with isotropic scattering, gray (no spectral dependency) and with transparent boundaries, using the Levenberg-Marquardt method and experimental data on the hemispherical reflectivity and transmissivity. Results are presented for some simulations using synthetic experimental data.

Key-words: Inverse problems, Radiative transfer, Absorption coefficient, Scattering coefficient, Levenberg-Marquardt.
 
 

Rafkat Toukhvatoulline - rafkat@main.unijui.tche.br
Gerson Feldmann - feldmann@main.unijui.tche.br
Helio Bonadiman - helio@main.unijui.tche.br
Departamento de Física, Estatística e Matemática. Universidade de Ijuí - UNIJUÍ,
DeFEM, Rua São Francisco, 501, Cx.P. 560-987000-000-Ijuí-RS-Brasil

The model of plasma torch with cylindrical symmetry in the presence of temperature oscillations and of space pulsations was studied. Starting from the lateral radiations, we calculated the radial distributions of the temperature for the stationary and not stationary plasma. The effect of the pulsations was studied for different standard-deviation values of the position of the axis and of temperature. The calculations were made for the spectral line Ar I 435,8 nm. The results show that the pulsations of the plasma can influence significantly the experimental results and they can be the cause of differences between the theoretical calculations and the experimental measures monts.
 
 

Lin Chau Jen - linchau@ipt.br
Instituto de Pesquisas Tecnológicas, Divisão de Mecânica e Eletricidade, Cx. P. 0141 -
01064-970 - São Paulo - SP
Clemente Greco
Escola Politécnica da USP, Departamento de Engenharia Mecânica, Av. Prof. Luciano
Gualberto S/N, Travessa 3, nº 380, 05508-900, São Paulo, SP

In this paper, the operation of a heat exchanger was simulated through a CFD computational code. The heat exchanger is composed by two concentric tubes, with combustion gases flow in the inside tube and air flow in the cylindrical annulus. The flows are turbulent and cocurrent. The main focus was the calculation of radiation heat transfer term, applying the discrete ordenates method. This paper shows the conceptual simplicity and the operational facility of the method, easy to integrate within a CFD program.

Keywords. Radiation, Furnaces, Discrete Ordenates Method.
 
 

Fernando D. Foroni - e-mail: dalessio@h8.ita.br
Marcelo J.S. de-Lemos - e-mail: delemos@mec.ita.br
Departamento de Energia - IEME, Instituto Tecnológico de Aeronáutica - ITA
12228-900 São José dos Campos - SP - Brasil

The present analysis accounts for combined convective and radiant heat transfer to a fluid flowing in a short tube with prescribed wall heat flux. The heat flux distribution used was of sine shape with maximum at the middle of the tube. This solution is known to represent the axial power variation in a nuclear reactor core. The tube wall and gas bulk temperatures were obtained by successive substitutions for the wall and gas energy balance equations. The integrals were approximated by Sympson's rule and initial guesses for the iterative process were based upon limiting cases for pure radiation and pure convection. Results were presented for the cases of constant and variable film coefficient along the tube.
 
 

Vicente de Paulo Nicolau, vicente@lmpt.ufsc.br
Fernando Pires Maluf;
Fabiano José Balen.
Universidade Federal de Santa Catarina - Departamento de Engenharia Mecânica.
Laboratório de Meios Porosos e Propriedades Termofísicas
C.P 476 - 88010-970 - Florianópolis, SC, Brasil

Spectral radiative properties of commercial clear glass are identified, like the index of refraction and the absorption coefficient. Such identification takes place in the visible and near infrared region of the electromagnetic spectrum. The method is performed with transmittances and reflectances measurements. Samples with different thickness are tested. The complete set-up as well as some experimental results are presented and discussed in the paper.

Keywords: radiative property, thermal property, absorption coefficient, index of refraction, glass.
 
 

Rosana da Paz F. Pinheiro - rpaz@iprj.uerj.br
Francisco D. Moura Neto - fmoura@iprj.uerj.br
Antônio J. Silva Neto * - ajsneto@iprj.uerj.br
Instituto Politécnico, Universidade do Estado do Rio de Janeiro, CP 97.282, CEP 28601-970,
Nova Friburgo, RJ, Brasil.

Operator splitting and integrating factor methods are presented for the solution of the Boltzmann equation in one-dimensional homogeneous participating media with internal sources, with isotropic scattering, gray (no spectral dependency), with diffusely reflecting boundaries subject to external isotropic radiation sources. Several test cases are considered and results are compared with the discrete ordinates method and the global basis Galerkin method.

Keywords: Radiative transfer, Participating media, Discrete ordinates, Operator splitting, Integrating factor.
 
 

 Issamu Muraoka - issamu@dem.inpe.br
INPE - Instituto Nacional de Pesquisas Espaciais
Av. dos Astronautas, 1758 - São José dos Campos - SP- Brazil

This paper describes the development of the thermal design of SACI-1 satellite, launched in October 1999 by the Chinese rocket Long March 4. To satisfy the temperature requirements, a passive thermal control was designed and implemented on this satellite. A numerical model, based on the lumped parameter method, was implemented and used as a tool during the design process. Several tests were performed on the thermal mockup and the flight model, in the thermal-vacuum chamber, to verify the thermal design performance and check the mathematical model.

Keywords: Satellite thermal control, Saci-1