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Part I. Theoretical calculations of equilibrium infrared gas emissivities from spectroscopic data. Part II. Representative radiative energy transfer calculations for transparent and optically dense media

Citation

Gray, Louise D. (1963) Part I. Theoretical calculations of equilibrium infrared gas emissivities from spectroscopic data. Part II. Representative radiative energy transfer calculations for transparent and optically dense media. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:04182012-135901615

Abstract

Part I. Measured data for carbon dioxide emissivities at temperatures up to 1800°K have been correlated by postulating (a) that the effective spectral region widths, in which significant contributions are made to the total emission of radiant energy, increase with temperature and optical depth, and (b) that unknown combination and harmonic bands make contributions to the integrated intensities of selected spectral regions in such a way that the absolute values of the integrated intensities (cm^(-2)atm^(-1) remain invariant with temperature.

Spectral emissivities have been calculated in the infrared for hydrogen chloride to the rigid-rotator harmonic oscillator approximation using the "smeared-out" rotational line model for temperatures of 600 and 2400°K. In the weak-line approximation, this model gives reasonable agreement with numerical calculations. In the strongline approximation, there is quite a large discrepancy, particularly in the P-branch, at 2400°K; much better agreement is obtained if vibration-rotation interaction and anharmonicity terms are included in the calculation.

Equilibrium spectral emissivities have been computed for water vapor by using available low-temperature spectroscopic data. Satisfactory agreement with experimental results at 1111°K is obtained if the nearly symmetric top expressions for integrated intensities are used in conjunction with the just-overlapping line model.

Part II. The general equations of radiative energy transfer are presented. When the absorption coefficients and/ or the gas volume are sufficiently large, the general transport equation can be approximated by the "diffusion approximation". This approximation is applied to a two-phase system consisting of carbon- particles dispersed in a gas. The Rosseland mean absorption coefficients are calculated for spherical carbon particles of 200 and 987 A radius at temperatures of 1000 and 2000°K, and a comparison is made of the relative magnitudes of conductive and radiative heat transfer for this system.

In the special case when scattering may be neglected, and the temperature and pressure of the gas are constant, the transport equation can be integrated for a particular direction. The total radiant energy transfer to any given element of area depends upon geometrical interchange factors. These interchange factors have been evaluated for centrally located areas in cylindrical and conical chambers; simple relations are given for a transparent gas and an optically dense gas. A represei1ative calculation has been carried out for the radiant energy transfer to a centrally-located area element at the plane of intersection of two truncated cones.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Engineering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Engineering and Applied Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Penner, Stanford S.
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1963
Record Number:CaltechTHESIS:04182012-135901615
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:04182012-135901615
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6944
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:18 Apr 2012 21:20
Last Modified:26 Dec 2012 04:41

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