Band models for nonisothermal radiating gases

Area of Science:

• Thermodynamics
• Spectroscopy
• Radiative Transfer

Background:

• Accurate calculation of spectral radiance is crucial for understanding energy transfer in gases.
• Nonisothermal gas conditions present challenges in radiative transfer modeling.
• Existing models may require refinement for specific spectral regions and conditions.

Purpose of the Study:

• To develop approximate relations for calculating the mean spectral distribution of net radiance.
• To validate these relations using experimental data for water vapor bands.
• To propose a more general band model for intermediate optical depths.

Main Methods:

• Utilized experimental spectral absorptance data.
• Calculated mean spectral distribution of net radiance.
• Compared calculations with experimental data for 2.7-micrometer bands of H(2)O.
• Investigated variations in temperature (900-1200 K) and pressure along a 60-cm path.
• Employed a strong-line model for initial comparisons.

Main Results:

• Approximate relations were established for net radiance calculations.
• Experimental data for water vapor (H(2)O) bands validated the proposed relations.
• The strong-line model showed agreement with experimental findings.
• A new band model expression was proposed for intermediate optical depths.

Conclusions:

• The developed approximate relations provide a viable method for spectral radiance calculation in nonisothermal gases.
• The study confirms the applicability of spectral absorptance data in these calculations.
• The proposed general band model offers potential for broader applications in radiative transfer.