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Banca de QUALIFICAÇÃO: GABRIEL DE LIMA BERNARDINO

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : GABRIEL DE LIMA BERNARDINO
DATE: 03/02/2020
TIME: 14:00
LOCAL: Sala 414 do CTEC - UFRN
TITLE:

A study of an approximation for the absorption cross-section in which one or more thermodynamic properties are assumed as constant in radiation heat transfer in non-uniform participating gases.

KEY WORDS:

absorption cross-section, pressure, temperature, molar fraction, line-by-line calculations.

PAGES: 81
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUBÁREA: Fenômenos de Transporte
SPECIALTY: Transferência de Calor
SUMMARY:

Accurate computations of radiative heat transfer in participating gases require detailed knowledge of the spectral data of radiative properties. This can be achieved either performing line-by-line calculations or using an accurate spectral model. In both cases, the absorption cross-section is computed from high resolution databases, which use to contain parameters for millions of spectral lines. The absorption cross-section depends on the local thermodynamic gas state, being a

function of temperature, pressure and chemical species concentration, which vary
with location in non-uniform gases. Therefore, the absorption cross-section must be
computed and stored for diverse gas states, requiring considerable computational
resources. In addition, the dependence of the absorptions cross-section with local
gas properties poses complexity in radiation problems involving participating gases.

This work proposes and evaluates an approximation in which the absorption cross-
section is obtained by taking one or more thermodynamic properties as constant.

Results of radiative transfer based on this approximation are obtained and analyzed. The local properties are temperature, molar fraction of each chemical species and pressure. The approximation reduces problems complexity and the size of the absorption cross-section database. It was evaluated for gases composed by CO2 and air, H2O and air, and mixtures of CO2, H2O and air. Uniform and non-uniform media were considered. Molar fractions of CO2 and H2O from 5 % to 100% were considered, while temperatures varied from 500 K to 2500 K. Pressure was always 1 atm, except for those related to the approximation, where the pressure was assumed constant and equal to 3 atm. Results demonstrated that the approximation in which the absorption cross-section is obtained for a fixed molar fraction can be highly accurate when applied to non-isothermal and non-uniform gases.

BANKING MEMBERS:
Presidente - 2014591 - ANDRE JESUS SOARES MAURENTE
Interno - 1753416 - EDUARDO JOSÉ CIDADE CAVALCANTI
Externa à Instituição - ALINE ZIEMNICZAK - UFRGS

Notícia cadastrada em: 24/01/2020 22:43