Nongrey gas radiation analyses were conducted using the statistical narrow-band model and four implementation methods : the exact or the correlated formulation, the noncorrelated expression, greyband approximation based on global absorption coefficient, and a new approximate method. The new method is also a grey-band approximation but utilizes the local absorption coefficient. Using results of the correlated formulation as benchmark solution, accuracy of the three approximate narrow-band implementation methods was investigated for several one-dimensional non-grey gas radiation problems in parallel plate enclosure containing radiating gases of both uniform and non-uniform temperatures and/or concentrations. Radiative source term and wall heat flux predicted by the noncorrelated expression and the new method are in very close agreement with each other and in fair to good agreement to benchmark solutions. Radiative source term calculated from the grey-band approximation based on global absorption coefficient is in serious error. CPU time saving of two orders of magnitude can be achieved by using the three approximate implementation methods, relative to the correlated formulation. The new method provides slightly better accuracy than the noncorrelated approach with additional advantages that an arbitrary solution method can be employed and less CPU time is required.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Mechanical Engineering
- Fluid Flow and Transfer Processes